Title of Invention	A TONE RING ASSEMBLY
Abstract	This invention relates to a tone ring assembly for use on a rotatable machine part. The tone ring (10) is able to generate a varying voltage output when rotated at varying speeds. A fixed position magnetic sensor detects the voltage. The tone ring comprises an axially extending main body portion (18) having a plurality of areas able to generate a voltage upon rotation. A retainer (75) having at least one radial flange (82,83) prevents axial movement of the tone ring (10) and the tone ring includes ribs (46) and spaces (48) on its inside diameter to permit oil to pass therethrough.

Title of Invention

A TONE RING ASSEMBLY

Abstract

This invention relates to a tone ring assembly for use on a rotatable machine part. The tone ring (10) is able to generate a varying voltage output when rotated at varying speeds. A fixed position magnetic sensor detects the voltage. The tone ring comprises an axially extending main body portion (18) having a plurality of areas able to generate a voltage upon rotation. A retainer (75) having at least one radial flange (82,83) prevents axial movement of the tone ring (10) and the tone ring includes ribs (46) and spaces (48) on its inside diameter to permit oil to pass therethrough.

Full Text	This application is a continuation-in-part of copending U.S. Patent Application No. 10/012,880, filed November 2, 2001. BACKGROUND OF THE INVENTION The present invention relates to an assembly including a so-called tone ring or exciter ring and a magnetic sensor unit. More particularly, the present invention relates to a portion of a vehicle or other mechanical assembly which is adapted to create a signal of varying voltage output when rotated at varying speeds, with such signal being detected by a pickup or sensor unit with which the rotary part is associated. The tone ring preferably has a large plurality of teeth, vanes or lands separated by spaces or grooves therein or can also be a simple cylinder with strips of magnetic rubber molded into it or otherwise fastened to it. Passing the lands or magnets by a fixed sensor at varying speeds creates a speed-varying signal in the sensor and gives an indication of the rotational speed of the shaft with which the tone ring is associated. The assembly is primarily intended for vehicles wherein the rotational shaft speed, and particularly variations in the rotational speed of two or more shafts, is sensed for various purposes. These include use in ABS (anti-lock braking systems), differential actuation or control, traction control, all-wheel drive control, vehicle stability and the like. In addition, the invention can be used in other applications, such as sensing the 2 rotational speed of power take-off shafts or other power transmission devices including one or more rotary shafts. In the past, tone rings have been fitted onto axle shafts or other rotating members by press fitting them into place like a bearing or seal. This method can be cumbersome at best, and impossible at worst. Other methods of incorporating tone rings on rotary mechanisms involved integrating the tone rings with bearings or with the hubs or with the ring gear, with the tone ring being associated with the rotary part. Because the shaft undergoes deflection in use, and for other reasons, these methods are sometimes not satisfactory, especially where the bearing/sensor system is too rigid to accommodate such shaft deflection in use. Other tone rings or proposals for tone rings involve installing forces that might easily damage the tone ring or sensor. Still others would lack a unitizing feature, wherein means are provided to prevent axial movement of the tone ring beyond certain limits, or where installing a retainer determines the position of the tone ring, at least approximately. If a tone ring assembly could be provided which was unitized, as a system approach, it would result in simplified assembly. Likewise, if a tone ring could be made that had mating components installable with low force, especially a construction in which, after installation, the tone ring would grip the shaft more tightly than during initial installation, it would be highly desirable. There are some preferred features of construction whereby initially locating the tone ring on the shaft would be made easier, while ultimate gripping of the shaft essentially would not be compromised. In 3 other words, the force needed to install the tone ring over the shaft would, for reasons of geometry or surface texture, initially be minimal. Particularly, if a tone ring assembly were provided which would be associated with a part of the shaft which underwent little or no deflection in use, it would be greatly advantageous. Were these advantages attainable in a design which provided at least one, and preferably more than one, axial oil passages in use, it would be very desirable. It would also be desirable to provide a unitizing retainer in the form of a sleeve with radially inner and outer portions to engage and package a radial flange of the tone ring, or the entire tone ring itself and allow only a limited range of axial movement between flanges of the retainer and tone ring or limited movement of the entire tone ring. Also, this unitizing retainer could be made of one piece in stamped steel or formed in a tough plastic such as Delrin. Accordingly, it is an object of the present invention to provide an improved tone ring element able to generate a voltage output by rotation, preferably either in the form of a sleeve having multiple lands, grooves, teeth or magnets for signaling an associated magnetic sensor or pickup as the tone ring lands or magnets rotate past the sensor. By "tone ring" or like words is meant not-only a single ring element, but also a plurality of rings, working in concert with sensors connected to or* associated with a rotational speed differential computer and feedback mechanism. 4 Another object of the invention is to provide a tone ring assembly which is separate from the bearing or seal assembly yet which is associated with an axle shaft supported on such bearings. Yet another object of the invention is to provide a tone ring assembly which is sufficiently flexible and positioned such that it is able to accommodate limited axle shaft deflections in use, and also accommodate a limited amount of end play in such shafts. Still another object of the invention is to provide a tone ring and retainer which can initially be installed by an ergonomically acceptable force by placing it with an installation tool in place within the axle tube or housing and then sliding the axle shaft through the tone ring with ergonomically desirable forces and just past its functional position in the application to permit an axially inner axle shaft retainer or "C" clip to be installed in a groove in the axle shaft. Thereafter, when the axle shaft is moved just slightly axially outwardly, the clip and the tone ring are centered or aligned axially in place. A further object of the invention is to provide a design of tone ring and retainer which can be positioned so as to be in an area of the shaft which undergoes minimum deflection in use. A still further object of the invention is to provide a design which is unitized for simple and relatively foolproof assembly. An additional object of the invention is to provide a tone ring which, while installing easily, will thereafter use the swell of rubber in reaction to 5 assembly and/or subsequent application lubricant to develop a more firm grip on the shaft. A still further object of the invention is to create a design of tone ring having an interior diameter including an oil passage or largest diameter, a diameter for the ribs or splines adapted to swell into contact with the shaft and finally, a small portion with an innermost diameter adapted to initially contact its associated shaft. Another object of the invention is to provide a design which is compatible with the axle configuration so that there is sufficient axial travel of the axle shaft to enable a retainer or "C" clip to be dropped in place over the axially inner end of the axle shaft, and thereafter, enable the axle shaft to be pulled out a few millimeters to seat the clip, thus loading a thermoplastic or thermoset spacer as the tone ring slides slightly out to a "home" position on the shaft. This spacer can be eliminated if more axial width for retainers is available. It can also be eliminated if the retainer or toner ring flange is made of thermoset or thermoplastic material. Yet another object of the invention is to provide a tone ring which lies axially inside the seal and bearing, but is held in position axially by engagement between the opposed flanges of the retainer and the flange of the powdered metal sleeve. It is initially held radially by inner diameter ribs on the tone ring, and thereafter held more firmly in place by lubricant induced swelling of these radial ribs. This may take place in steps or stages, if desired. The powdered metal flange may be eliminated or the powdered 6 metal tone ring/flange combination may become two or more pieces assembled or molded as an alternate design. Still another object of the invention is to provide substantial axial width of the tone ring teeth so the location of the sensor relative to the tone ring accommodates any variation in the stack-up or end play tolerances in the application. Another object of the invention is to provide a tone ring that will fit over the smallest machined diameter of an axle shaft, leaving larger respective diameters for accommodating the bearings and the oil seal, respectively and allowing the components to be assembled inside the axle tube. A further object of the invention is to provide a tone ring assembly which inherently allows a desired or correct assembly sequence with the axle shaft, the seal, the bearing and the tone ring. The tone ring assembly can also be reused after disassembly in the field. An additional object of the invention is to provide a tone ring assembly which will allow passage of oil along one, two paths through the tone ring. Another object is to provide a textured surface on some or all of the ribs on the tone ring so that these ribs can, in effect, "hold" the oil or grease against the shaft, Ibr ease of, or better lubricated, installation. A still further object is to use various processes, such as electrical discharge machining (EDM) or Chemical Etching to roughen or create a textured surface on the tooling used to make the rubber part, consequently 7 imparting a textured surface on the inside of the ribs or splines in the finished, molded product. The invention achieves these objects and others which are inherent therein by providing an assembly which includes a rotatable tone or exciter ring able to generate a varying voltage output by rotation relative to a magnetic sensor, and ribs on its inner diameter, which includes an optional radial flange, optionally an abutting spacer with radial oil passage spaces, a retainer having at least one radial flange, one or more oil passage features, with the associated sensor being adapted to pick up a speed varying signal as the lands or magnets on the tone ring sleeve pass by the sensor. The manner in which these and other objects of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the present invention set forth by way of example and shown in the accompanying drawings, in which like reference numerals indicate corresponding parts throughou BRIEF DESCRIPTION OF THE ACCOMPANYIN/REVICE GDRAWINGS FIG. 1 is a perspective view of one form of the tone ring and the retainer showing these parts in their assembled condition, and taken from the axially inner end of the tone ring; FIG. 2 is an exploded fragmentary perspective view of the tone ring assembly of FIG. 1, taken from the axially outer end so as to illustrate the component parts of the retainer, the preferred form of spacer and the various features of these parts and the tone ring; FIG. 3 is an exploded fragmentary perspective view of the tone ring assembly of FIGS. 1 and 2, and showing the retainer in two parts, and the spacer as well as the tone ring from the axially inner end thereof; FIG. 4 is a horizontal sectional view of the tone ring assembly, including the retainer, the spacer and the tone ring in their installed positions within the axle housing and over the axle shaft, and showing the seal and bearings in position encircling the shaft; FIG. 5 is a fragmentary view, with portions broken away, showing an alternate embodiment of the invention; and, FIG. 6 is a fragmentary view, with portions broken away, showing an embodiment of the invention wherein the sensor is positioned over a window or opening in the retainer. FIG. 7 is a perspective view looking at the inside of the tone ring and showing a stepped portion on some of the ribs or splines on the inside diameter of the tone ring; FIG. 8 is a greatly enlarged view of one of the ribs containing the . stepped portion as shown in FIG. 7;. FIG. 9 is a view taken from the inside of the tone ring body and showing the textured portions on the innermost surfaces of the mounting ribs or splines on the i.d. of the tone ring; and FIG. 10 is a greatly enlarged view of one portion of one of the ribs of FIG. 9, showing details of its textured surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 9 While the tone ring may be embodied in many applications, including automotive and non-automotive applications such as power take-offs, generators and others, a detailed description of the tone ring or exciter ring assembly and its auxiliary components including the detector or sensor will be given first in an application wherein a vehicle drive axle shaft rotates the tone ring, the sensor is located in a fixed position in the axle tube housing just radially outside or removed from the tone ring surface, and an optional flange on the tone ring holds the ring in a fixed position by reason of contact between the flange and a flange of the retainer, preferably with an optional spacer between the tone ring and the retainer. Referring now to the drawings in greater detail, FIGS. 1-4 show a tone ring assembly generally designated 10, preferably located axially inside the wheel bearing within an axle tube housing assembly generally designated 12, wherein a sensor 14 is held in fixed position within an opening generally designated 16 in the housing assembly 12. The tone ring body, generally designated 18, includes an axially extending portion 20, a radial flange 22 defined by axially inner and outer surfaces 24, 26 and a radially outermost, stepped surface generally designated 28. The body generally designated 18 includes a radially outer surface generally designated 30 on the axially extending portion 20, the axially inner portion of which is defined by alternately radially extending lands 32 and grooves 34, preferably extending directly purely axially. The radial flange 22 has a stepped surface 28, having a major diameter surface 35 and a minor diameter surface 36 therein for the axial 10 passage of oil. The inside of the tone ring body 18 includes a rubber portion generally designated 38, and this portion includes a beveled lead-in area 40. In addition, there are plural axially extending ribs 46, each of which includes a lead-in area 44. The ribs 46 are spaced apart by axially extending grooves 48. The ribs 46 snugly engage the outer diameter 49 of the axle shaft shown as 50, by engaging a portion 52 thereof which is of intermediate size, being slightly larger in diameter than the axially inner portion 53 of the shaft and smaller size than the portiqn 54 engaging the inside diameter 56 of the bearing generally designated 58. The bearing 58 is shown to include roller elements 60, and an outer retainer 64. The actual type of bearing may vary, and, for example, may feature the rollers 60 indirectly engaging the shaft, or being free from a bearing cage or other locator. Oil may pass axially through the grooves 48 in the tone ring 18 from the differential (not shown) to the bearings 58 and to the seal generally designated 66. Although not a necessary part of the invention, the seal 66 is shown typically to include a casing or stamping 68 and a rubber primary lip 70. The seal is shown with an auxiliary or dirt lip 71 as is typical with vehicle axles, but this is not strictly necessary. The tone ring body 18 does not move measurably axially once it is finally installed in the appropriate position over a portion 52 of the shaft 50. In addition to being held by the friction of the ribs 46, the body 18 is also held in a final axial position by a tone ring retainer generally designated 75. 11 Preferably, but not necessarily, the retainer generally designated 75 is made from two components, a thicker gauge radially outer indented casing generally designated 76 and a thinner gauge radially inner casing generally designated 78. The radially inner casing 78 includes an axially extending portion 80 and a radially inwardly extending retaining flange 82, while the outer casing generally designated 75, into which the inner, thinner casing 80 is pressed, includes a radially inwardly extending retainer flange 83, a generally axially extending portion 84 which includes a corrugated exterior surface portion generally designated 88. Thus, the portion of the casing generally designated 88 includes both raised portions 90 which engage the counterbore 92 and depressed portions 94 which permit axial passage of oil. There are also scalloped cut-outs 97 or relieved areas in the radial flange 83 of the retainer 88. Thus, oil flow may be inside the body 18, or between the tone ring 18 and the retainer 88. The result upon final assembly of the components is a U-shaped retainer in cross-section having flanges 82, 83 which will prevent undesired axial movement of the tone ring body 18 in either direction. Referring now to another preferred element of the invention, a spacer generally designated 96 is shown to be confined between the radial flange 82 of the inner casing 78 and the axially outer surface 26 of the radial flange 22 of the tone ring 18. This spacer 96 includes a continuous inner portion 98 and a plurality of teeth 100 separated by spaces 102. Preferably, the teeth 100 include beveled end portions 104 and flat, axially inner and outer surfaces 106, 108 to facilitate engagement of the radial flange 82 of the radially inner casing 78 and the axially outer surface 26 of the tone ring radial flange 22. The tone ring body 18 may also have a groove 110 or relieved portion adjacent the radial flange 22 to provide extra clearance between the body 18 and the radial flange 83 of the retainer 75. Assembling the tone ring with its mating parts is a fairly straightforward operation. The axle shaft 50 includes a smaller diameter portion 53 throughout most of its length. As the axle shaft 50 approaches its axially outer end, however, the diameter is very slightly enlarged as at 52, and the axle shaft 50 includes another step lying toward a larger diameter surface 54 terminating before the flange generally designated 57. The sensor generally designated 14 is positioned properly relative to the lands and grooves on the tone ring body 18 at this time or later. Since it does not interfere with the tone ring, it can be inserted at any time. The retainer 75 is then placed in the counterbore 92 with a light press fit, while the tone ring body is held within the retainer. The tone ring is held such that it does not tilt excessively, and thus is positioned to receive the axle. No other means is required to guide the axle shaft into position within the body 18. Next, the bearing unit 58 is positioned with its outer retainer 64 pressed into its just larger counterbore 95, and finally, the casing 68 of a seal unit 66 is pressed into the largest counterbore 101. The axle shaft 50 is then inserted gradually until it engages the tone ring 18 on its inner diameter ribs 46. Then, with the tone ring resisting 13 further inward movement by reason of engagement between the radial flange 83 of the retainer 75 and the tone ring flange surface 24, the axle shaft 50 is pushed gradually axially inwardly (to the right as shown in FIG. 4) until the innermost end of the axle shaft is positioned to receive a C-clip (not shown) for holding the axle shaft in position. Thereafter, the axle shaft is withdrawn axially a few millimeters so the C-clip is properly engaged and seated in the differential. This moves the tone ring slightly to the left as shown in FIG. 4 and insures that the axially outer surfaces 108 of the spacer teeth 100 will engage the retaine&-flange, if necessary, sliding the tone ring body 18 slightly axially inwardly relative to the axle shaft and insuring that the body is properly positioned against spacer 96 which is positioned against retainer flange 82. Thus, the installation is self-aligning and self-centering, which is very desirable. Once the installation is made, another axle shaft may be reinserted in the application by simply pushing it, usually by hand, into place within the tone ring body. Of course, if the original axle shaft were removed, it could be reinserted inside the tone ring. The materials from which the tone ring are made are conventional for this application. For example, the tone ring itself may be made from a ferrornagnetic^powderedjrie.tal, which is die-formed then sintered into the desired finished form. Other materials may be used, but powdered metal technology may be preferred by reason of its affording relatively deep, square lands and grooves as well as its cost-effective magnetic properties. Metal embedded in plastic can also be used, including magnetic strips laid out 14 axially, and then covered with an elastomer or a plastic material which is permitted to harden. The rubber used to form the ribs 46 and the surrounding material is an EPDM or other suitable elastomer such as so-called Nitrile (NBR), HNBR, FKM, AEM, ACM or other elastomer. Plastics or thermoset materials can also be used as outlined above in another suitable form. The ribs 46 and surrounding portions 40, 42 of the elastomer may be coated with a dried PTFE material for lubrication, and the substrate may be made from a thermoplastic or thermoset material. For purposes of lubrication, a wet lubricant such as oil, grease or an ammonium alkyl phosphate may be placed on the ID of the tone ring. Both parts of the retainer are preferably made from mild steel but plastic could also be used. The spacer is an insulating, lubricous material such as Delrin or acetal material, but it possibly could be replaced by a low friction coating on the retainer or on the tone ring flanges, or both, or eliminated completely. The retainer is fabricated for convenience in two pieces, an inner, thinner piece and an outer, thicker piece, but it could be made in a single piece. The illustrated form has the corrugations in one part of the retainer, which is then combined with a thinner, flat portion to make the radial flanges. The rubber material used in forming the ribs 46 is of the type that will swell in the presence of oil or grease, including oils with extreme pressure additives therein. Consequently, when the tone ring is installed over the axle, it may be located easily, but after the tone ring has been in 15 place for a time, the oil further swells the rubber and the tone ring is held much more firmly in place. As alternate designs, one may also provide several other constructions. In one such construction, which would be the simplest of these, and is illustrated in Fig. 5, the tone ring generally designated 18a could simply not have the radial flange, which now affords the simplest way for the retainer to insure that the tone ring does not excessively move axially on the shaft during installation. Instead, there is a groove 110a in the body 20a of the tone ring 18a, and a flange 82a extending into the groove 110a. In such a construction, the axial extent of the tone ring would be much larger than the axial extent of the retainer in the first embodiment, but the counterbore 92a would have the axial flange 80 pressed into it. The sensor 14a rests in an opening 16a. In this way, a unitized construction would also be provided. Another alternate construction is shown in Fig. 6. Here, there is no groove or flange, but the retainer 78b is allowed to span the entire axial length of the tone ring with both flanges 82b, 82b thereby confining the body 18b against the axial movement. In such a construction, of course, it would be necessary to provide an opening or window 99 in one portion of the retainer so that the sensor 14b could function properly. As previously indicated, the spacer may be eliminated, and in its place, a lubricous coating could be placed on the face of the radial flange 26 of the body, or on the inner face of the flange 82, or both. This expedient could be used in the interest of ultimate cost savings, particularly where there would be little or no risk of significant axial movement of the tone ring after installation, that is, during operation. In the further alternative, the spacer could be made of a hard grease block material, thereby being adapted to dissolve after significant contact with the radial flange of the body and the radial flange of the retainer. It is important that there be at least one axial oil passage in the assembly, and preferably, several passages. The most advantageous way of providing these passages is to space the tone ring body apart from the axle shaft by a series df^shallow ribs, and then also provide passages in the spacer, the retainer, and in the tone ring flange4which periodically come into registration to allow the passage of oil through the part. These are useful ways to provide lubrication to the bearings with oil traveling from the differential. It is sometimes thought advantageous for ease of axle shaft installation that the inside diameter of the tone ring be especially adapted to slip more readily over the shaft, without however, compromising the ability of the tone ring inside diameter (I.D.) to swell in the presence of oil and hence tightly grip the shaft. This may be done in two different ways, merely by way of example. Referring now to FIGS. 7 and 8, there is shown a modified tone ring generally designated 200 and a retainer generally designated 275. The other features of the tone ring, such as its spaced apart lands and grooves on its O.D., etc. are identical to its earlier shown embodiments. It is only in the construction of the rib 246 that a difference occurs. Here, the rib itself, 17 about halfway along its extent, contains a reduced diameter portion generally designated 247 having a generally flat inwardly directed contact surface 250 and tapered entry and exit surfaces 248, 249. The surface 250 is offset from the remainder of the rib 246, typically about ten thousandths of an inch. (0.010 inches). The surface 250 is about 5 mm or 200 thousandths (0.200 inches) long. Typically, every third rib 246 contains one raised portion 247, although more or fewer ribs 246 may each have a raised portion 247. In use, the portions 247 of the ribs 246 in some cases render the tone ring easier to install. This is because only the raised portions 247 are in contact with the shaft during installation. However, when the grease or oil on the shaft has an opportunity to react with the rubber, the rubber expands and secures the tone ring in a more fully locked position relative to the axle shaft. The design of the portion is such that it includes two tapered areas 248 and 249 which protect the raised portions from damage during installation, and accommodate axial movement during installation. As pointed out, once the oil or grease reacts with the rubber, the ribs 246 are more securely locked in place. Another manner of achieving the same effect is illustrated in FIGS. 9 and 10. Here, the tone ring generally designated 300 is identical in all respects with its counterpart shown in FIGS. 1-3, for example. The only exception to this identity is in the construction of the ribs generally designated 346. The spaces between the ribs 48 are identical, and the 18 makeup of the modified, textured ribs 346 is the only difference in these tone rings. Here, the surface designated 350 contains a texture. The surface thus contains a series of generally flat portions lying in a plane, but also contains a very large number of smaller portions 354 having an indented or textured random pattern. The pattern shown in FIG. 10 is merely for illustration, it being understood that the portions with the slightly enlarged diameter or countersunk portions are from 2 to 10 thousandths of an inch (0.002 -0.010), preferably about 5 or 6 thousandths (0.005 - 0.006 inches). The manner of making this pattern in the molded rubber part is relatively simple. The electrical discharge machining (EDM) anode tip used to form the rib geometry on the molding tool is designed to be very rough, and as a result, the tooling used to make the rubber products in this area takes on a rough, textured appearance. Consequently, the rubber that is formed or molded in this tooling has a mirror image impression of the texture on the molding tool. Consequently, the ribs generally designated 350 take on a textured character on their inner surface. This texturing can alternately be achieved by chemical "etching" of the subject tool area. For example, acid is used in selected areas to create "pockets" similar to the EDM approach. When it comes to installing these units, the textured portion creates "pockets" to hold the residual oil or grease against the shaft. Consequently, these "packets" hold lubricant and effectively create a film thickness of lubricant between the rubber and the shaft. This, in theory reduces the installation force. Consequently, this more lubricated construction may in some cases be preferred for ease of installation, especially bearing in mind that the axle shaft is made to a certain tolerance, which may be larger or smaller by a few thousandths of an inch. The simplest application of the tone ring assembly would be for use in controlling speeds of a single shaft, for example, a generator shaft. However, a more typical use of the tone ring and its associated parts is with two wheel drive vehicles, where the feedback from the sensor is sent to a computer g which then determines relative velocities of the two axles. For example, _ A ,u such a use would be in ABS systems (anti-lock braking systems), and I ,-A^\ tSfY differential control systems. M The tone rings are most advantageously used in four wheel drive systems, where the speed of each axle is desired to be governed by a computer having four or more inputs. Thus, the tone rings are useful, not only in various braking systems, but also in traction control systems where front wheel versus rear wheel speeds must be determined instantaneously, and where right versus left wheel speeds may be also measured instantaneously and then corrected, according to the design of the system. It will thus be seen that the present invention provides an improved tone ring assembly having a number of advantages and characteristics including those expressly pointed out herein, and others which are inherent in the invention. A few embodiments of the product of the invention, having been shown and described, it is anticipated that variations to the described form of apparatus will occur to those skilled in the art and that such modifications and changes may be made without departing from the spirit of the invention or the scope of the appended claims. 21a WE CLAIM 1. A tone rhg assembly 10 for use on a rotatable machine part 50, said assembly comprising tone ring 18 able to generate a varying voltage output when rotated at varying speeds, with a fixed magnetic sensor assembly 14 disposed in facing relation and closely spaced from said tone ring 18, said rotatable machine part 50 having an axially inner portion 53 and an axially output portion 54 running in a surrounding bearing unit 58, said tone ring 18 comprising an aiiafy extending main body portion 20 win a pluraity of areas 30 able to generate a voltage output upon rotation, a retailer 75 having at least one radial flange 82 to prevent substantial axial movement of said tone ring 18, said tone ring 18 comprising plural axially extending rtos 46 of reduced diameter on its Inner diameter for snugly engaging a rotating machine part, and having axial spaces of enlarged diameter 48 between said rbs 46, thereby affording passages for oil to pass axially said tone ring assembly 10. 2. A tone ring assembly as claimed in claim 1, whereh said tone rhg body 20 comprises a plurality of axialy extending lands 32 and grooves 34 therein. 3. A tone ring assembly as claimed in claim 1, whereh said tone ring body 20 comprises a pbrality of magnetic strips arranged fri an axially extending formation and spaced circumferenSalty apart from each other. 4. A tone ring assembly as claimed in claim 1, wherein said toe ring body 20 comprises a radial flange 22 formed on the axially outer end thereof. 21 5. A tone ring assembly as claimed in claim 1, whereri said at least one radial flange 82 on said retainer comprises two rediaf flanges. 6. A tone ring assembly as darned in claim 1, wherein said retainer 75 is comprised of two pieces, a radial Inner retaher portion 83 of generafly L- shaped and a radially outer retainer portion portion 82 of generally L- shape, both portions being combined to form a U-shaped assembly having axially inner and outer radial flanges. 7. A tone ring assembly as claimed ii claim 6, wherein said retainer 75 is a metal retainer made from two separate elements pressed and locked together. 8. A tone ring assembly as claimed In claim 7, wherein said radially outer portion 82 of said retainer 75 Is made from a thicker gauge of metal than said radially inner portion 83 of said retainer 75. 9. A tone ring assembly as claimed in claim 1, wherein said retainer 75 in made from a thermoplastic or thermoset plastic material. 10. A tone ring assembly as claimed fri claim 1, wherein said axially extending rtos 46 on the hner diameter of said tone rng assembly 10 have beveled end portions 44 so as to facilitate hstallatton over said rotating machine part. 11. A tone ring assembly as claimed h claim 1, comprising a spacer 96, tying h use between one end of said ring 18 and one flange 82 or 83 of said retainer 75, said spacer 96 being made from a low friction material which Is resistant to noise making when h at least occasional contact with said tone ring 18. 22- 12. A tone ring assembly as claimed h claim 1, wherein said at least one radial flange 82 of said retaher 75 comprises an axialiy hwardty feeing flange 80 on said retainer coated win an antt-frlctton material. 13. A tone ring assembly as claimed h claim 11, wherein said tone ring body 20 comprtshg a radial flange portion 22 adapted to engage a radial retainer flange 83, said radial flange 22 on said body 20 having areas of different diameters, with relief areas on said radial retainer flange 83, said spacer 96 having plural separate teeth 100 thereon, said teeth being engage able by an axialfy outer radial flange 80 of said retainer, thereby altowhg the passage of oil through the relief areas and said teeth areas. 14. A tone rrig assembly as claimed to claim 11, wherein said spacer 96 is made from a plastic material. 15.A tone ring assembly as claimed in claim 11, wherein said spacer 96 is made at least in part from a hard grease block. 16. A tone ring assembly as claimed in claim 4, comprishg a low friction coating material on the ax tally outermost portion 26 of said radial flange 22 on said tone ring body 20. 17. A tone ring assembly as claimed fri claim 4, whereh said radial flange 22 of said tone rhg body 20 is an assembled metal flange made from a different material than the reminder of said tone rtig body. 18. A tone rtig assembly as claimed h claim 11, wherein said spacer 96 is discontinuous at its outer diameter to permit oil flow axialty therethrough. 23 19. A tone ring assembly as claimed in claim 1, wherefc said rbs 46 of said tone ring 20 comprises an elastomer that is a blend of NBR and EPDM. 20. A tone rrig assembly as claimed in claim lr wheren said ribs 46 on said tone rhg 20 comprise at least one elastomer selected from (he class consisting of NBR, HNBR, B>DM, AB1 and ACM. 21. A tone ring assembly as claimed in claim 1, wherein said liner diameter of said tone ring 20 comprises a coating of dried PTFE. 22. A tone ring assembly as claimed in claim 1, whereh said rbs 46 on said Inner diameter of said tone ring 78 are made from a thermoplastic or thermoset material. 23. A tone ring assembly as claimed h claim 1, whereh said inner diameter of said tone ring comprises a wet lubricant coatrig selected from the class consisting of oil material, grease materials and ammonium afcyl phosphates. 24. A tone ring assembly as claimed h claim 4, whereh said radial flange 83 of said retainer 75 Includes cut-out portions 97 to permit oil to pass therethrough. 25. A tone ring assembly as claimed in claim 4, wherein said tone ring body 20 has, on said flange 22 thereof, a stepped diameter 35, 36. 26. A tone ring assembly as claimed n claim 4, wherein said tone ring 18 comprises an air gap lying between radially opposed portions of said tone ring body 20 and said radial flange 22 of said tone ring body for allowance 24 of maximum axle shaft deflection without touching the flanges 82,83 on said retainer 75. 27. A tone ring assembly as claimed in claim 1, comprising one of a removed rotating machine part SO, said axle shaft, and a separate axle shaft installed into the orlgfrial toe and retainer assembly. 28. A tone ring assembly as claimed ii claim 4, wherein said tone ring assembly is installable over an axle shaft 50 and held in place by interference between said tone riig body 20 and said flanges 82,83 on said retainer 75 durhg the entfre sequence of ^stalling the axle shaft 50. 29. A tone riig assembly as claimed h clakn 5, wherein said flanges 82,83, on said retainer 75 engage a radial flange 22 on said tone ring body 20 and provide a self-aligning feature and self-centering feature. 30. A tone ring assembly as claimed in claim 5, wherein said flanges 82,83 on said retainer 75 provide for accommodating axel tolerances stacked up in the assembly of the axle shaft. 31. A tone ring assembly as claimed In claim 1, whereh said retainer 75 has two radial flanges 82,83 and spans the axial width of the entire tone ring, said retainer 75 havhg an opening in at least one part of the axial extent thereof for receiving the sensor. 32. A tone riig assembly for use on a rotatable machhe part 50, said assembly 10 comprising a rotatable machine part 50, said assembly 10 comprises a rotatable tone ring 18 able to generate a voltage output by rotation ad a magnetic sensor assembly 14 disposed in facing relation and closely spaced from said tone rhg 18, said rotatable machine part 50 25 having an axialty inner portion 53 and an axially outer portion 54 running in a surrounding bearing unit 58 and with oil leakage being resisted by an oil seal 66, said tone ring comprfehg an axlally extending main body portion 20 with a plurality of lands 32 and grooves 34, which generate a votage outage output upon rotation, and a radially extending flange 22 at one end of said tone ring 18, a retainer 75 having axlafty liner 83 and outer 82 radial flanges to prevent substantial axiat movement of said tone ring, and a spacer 96 tying between said radialy extending flange 22 on said tone ring 18 and said axially outer radial flange 82 of said retainer 75, said tone ring having plural radially extending rbs 46 on its inner diameter for snugly engaging said rotatable machine part 50, the spaces 48 between said rbs 46 affordhg passages for allowing oil to pass axlalty through said tone ring 18. 33. A tone ring assembly as claimed h claim 32, comprising a groove 110a in said tone rhg body 20a lying between said flange 22 and tie remainder of said body 20a, said groove 110a receiving one of said axial flanges 82a of said retainer 75 ad preventing axial movement of said body 20a. 34. A tone rhg assembly for use on a rotatable machhe part 50, said assembly comprising a rotatable tone ring 18 able to generate a voltage output by rotation and a magnetic sensor assembly 14 disposed in facing relation and closely spaced from said tone ring 18, said rotatable machine part 50 having an axlalty inner portion 53 and an ax tatty outer portion 54 running in a surrounding bearing unit 58 and with oil leakage being resisted by an oil seal 66, said tone ring 18 comprising an axiafly extendhg main body portion 20 with a plurality of lands 32 and grooves 34 able to generate a votage output upon rotation and a radialy extendhg flange 22 at one end of said tone rhg 18, a retainer 75 havfcig axlalty inner 83 and outer 82 radial flanges to prevent substantial axial 26 movement of said tone ring 18, said tone ring having means permfcting passage of oil ax tally along said tone ring as well as means for engaging said rotatabie machine part 50 to locate said tone ring on said rota table machine part 50r said engaging means alkmiig said rotatabie machine part ad said tone ring to become more strongly adherent when said tone ring Is exposed to an oily condition. 35. A tone ring assembly as claimed ft claim 34, wherein said body portion 20 of said tone ring and said retainer 75 are so sized that upon Installation of said retainer ft the application counterbore, said body portion 20 is supported by said retainer 75, and presents an op en frig ft the ftslde diameter thereof that ts able to be aligned without addUonal aid with an axle shaft which is to be ftserted therethrough. 36. A tone ring assembly as claimed ft claim 34, whereh said flanges 82,83 on said retainer 75 permit said body to move ax tally inwardly ft one direction during installation to expose an axle dp, and to move ft the opposite direction to a position engaging said other axial flange through said spacer. 37. A tone ring assembly as claimed ft claim 1, wherein said tone ring body 20 is made from a powdered metal material, and wherein said radial flange ts made from a material other than that comprising said tone ring body. 38. A tone ring assembly as claimed ft claim 37, whereft said tone ring body 20 fe made from a powdered metal material and said radial flange 82 or 83 is made from a stamped metal material. 27 39. A tone ring assembly as claimed h claim 37, wherein said tone ring body is made from a powdered metal, material and said radial flange 82 or 83 Is made from a plastic material. 40. A tone ring assembly as claimed In claim 1, wherein at least one of said axialty extending rbs 246 of reduced diameter comprises a first portion and a second portion 250, said second portion 250 being of reduced diameter so as to initially engage said rotatable machine part 50 only and said first portion thereafter being adapted upon contact with oil and grease more into snug engagement with said rotatable machine part. 41. A tone rhg assembly as claimed fei claim 40, whereto said atfeast one of saW ribs 246 comprises plural rbs, 42. A tone rtog assembly as claimed to claim 40, whereh every third rib comprises said second portion 250. 43. A tone ring assembly as claimed to claim 1, whereto at least one of said axially extending rfes 246 comprises a portion factog said rotatable machine part 50, said portion having a large plurality of asperities and therefore a large plurality of pockets for fcibrleant. 44. A tone ring assembly as claimed to claim 43, whereto said at least one rto 246 comprises plural rbs. 45. A tone rtog assembly as claimed to claim 44, whereh every third rto comprises said second portion 250. 28 46. A tone ring assembly as claimed h claim 44, wherein at least one rfo 246 is formed by moldiig in a mold havitg surface asperities formed by electrical discharge machining or Chemical Etehhg. This invention relates to a tone ring assembly for use on a rotatable machine part. The tone ring (10) is able to generate a varying voltage output when rotated at varying speeds. A fixed position magnetic sensor detects the voltage. The tone ring comprises an axially extending main body portion (18) having a plurality of areas able to generate a voltage upon rotation. A retainer (75) having at least one radial flange (82,83) prevents axial movement of the tone ring (10) and the tone ring includes ribs (46) and spaces (48) on its inside diameter to permit oil to pass therethrough.

Full Text

This application is a continuation-in-part of copending U.S. Patent Application No. 10/012,880, filed November 2, 2001.
BACKGROUND OF THE INVENTION
The present invention relates to an assembly including a so-called
tone ring or exciter ring and a magnetic sensor unit. More particularly, the present invention relates to a portion of a vehicle or other mechanical assembly which is adapted to create a signal of varying voltage output when rotated at varying speeds, with such signal being detected by a pickup or sensor unit with which the rotary part is associated.
The tone ring preferably has a large plurality of teeth, vanes or lands separated by spaces or grooves therein or can also be a simple cylinder with strips of magnetic rubber molded into it or otherwise fastened to it. Passing the lands or magnets by a fixed sensor at varying speeds creates a speed-varying signal in the sensor and gives an indication of the rotational speed of the shaft with which the tone ring is associated.
The assembly is primarily intended for vehicles wherein the rotational shaft speed, and particularly variations in the rotational speed of two or more shafts, is sensed for various purposes. These include use in ABS (anti-lock braking systems), differential actuation or control, traction control, all-wheel drive control, vehicle stability and the like. In addition, the invention can be used in other applications, such as sensing the
2

rotational speed of power take-off shafts or other power transmission devices including one or more rotary shafts.
In the past, tone rings have been fitted onto axle shafts or other rotating members by press fitting them into place like a bearing or seal. This method can be cumbersome at best, and impossible at worst. Other methods of incorporating tone rings on rotary mechanisms involved integrating the tone rings with bearings or with the hubs or with the ring gear, with the tone ring being associated with the rotary part. Because the shaft undergoes deflection in use, and for other reasons, these methods are sometimes not satisfactory, especially where the bearing/sensor system is too rigid to accommodate such shaft deflection in use.
Other tone rings or proposals for tone rings involve installing forces that might easily damage the tone ring or sensor. Still others would lack a unitizing feature, wherein means are provided to prevent axial movement of the tone ring beyond certain limits, or where installing a retainer determines the position of the tone ring, at least approximately.
If a tone ring assembly could be provided which was unitized, as a system approach, it would result in simplified assembly. Likewise, if a tone ring could be made that had mating components installable with low force, especially a construction in which, after installation, the tone ring would grip the shaft more tightly than during initial installation, it would be highly desirable. There are some preferred features of construction whereby initially locating the tone ring on the shaft would be made easier, while ultimate gripping of the shaft essentially would not be compromised. In
3

other words, the force needed to install the tone ring over the shaft would, for reasons of geometry or surface texture, initially be minimal.
Particularly, if a tone ring assembly were provided which would be associated with a part of the shaft which underwent little or no deflection in use, it would be greatly advantageous. Were these advantages attainable in a design which provided at least one, and preferably more than one, axial oil passages in use, it would be very desirable.
It would also be desirable to provide a unitizing retainer in the form of a sleeve with radially inner and outer portions to engage and package a radial flange of the tone ring, or the entire tone ring itself and allow only a limited range of axial movement between flanges of the retainer and tone ring or limited movement of the entire tone ring. Also, this unitizing retainer could be made of one piece in stamped steel or formed in a tough plastic such as Delrin.
Accordingly, it is an object of the present invention to provide an improved tone ring element able to generate a voltage output by rotation, preferably either in the form of a sleeve having multiple lands, grooves, teeth or magnets for signaling an associated magnetic sensor or pickup as the tone ring lands or magnets rotate past the sensor. By "tone ring" or like words is meant not-only a single ring element, but also a plurality of rings, working in concert with sensors connected to or* associated with a rotational speed differential computer and feedback mechanism.
4

Another object of the invention is to provide a tone ring assembly which is separate from the bearing or seal assembly yet which is associated with an axle shaft supported on such bearings.
Yet another object of the invention is to provide a tone ring assembly which is sufficiently flexible and positioned such that it is able to accommodate limited axle shaft deflections in use, and also accommodate a limited amount of end play in such shafts.
Still another object of the invention is to provide a tone ring and retainer which can initially be installed by an ergonomically acceptable force by placing it with an installation tool in place within the axle tube or housing and then sliding the axle shaft through the tone ring with ergonomically desirable forces and just past its functional position in the application to permit an axially inner axle shaft retainer or "C" clip to be installed in a groove in the axle shaft. Thereafter, when the axle shaft is moved just slightly axially outwardly, the clip and the tone ring are centered or aligned axially in place.
A further object of the invention is to provide a design of tone ring and retainer which can be positioned so as to be in an area of the shaft which undergoes minimum deflection in use.
A still further object of the invention is to provide a design which is unitized for simple and relatively foolproof assembly.
An additional object of the invention is to provide a tone ring which, while installing easily, will thereafter use the swell of rubber in reaction to
5

assembly and/or subsequent application lubricant to develop a more firm grip on the shaft.
A still further object of the invention is to create a design of tone ring having an interior diameter including an oil passage or largest diameter, a diameter for the ribs or splines adapted to swell into contact with the shaft and finally, a small portion with an innermost diameter adapted to initially contact its associated shaft.
Another object of the invention is to provide a design which is compatible with the axle configuration so that there is sufficient axial travel of the axle shaft to enable a retainer or "C" clip to be dropped in place over the axially inner end of the axle shaft, and thereafter, enable the axle shaft to be pulled out a few millimeters to seat the clip, thus loading a thermoplastic or thermoset spacer as the tone ring slides slightly out to a "home" position on the shaft. This spacer can be eliminated if more axial width for retainers is available. It can also be eliminated if the retainer or toner ring flange is made of thermoset or thermoplastic material.
Yet another object of the invention is to provide a tone ring which lies axially inside the seal and bearing, but is held in position axially by engagement between the opposed flanges of the retainer and the flange of the powdered metal sleeve. It is initially held radially by inner diameter ribs on the tone ring, and thereafter held more firmly in place by lubricant induced swelling of these radial ribs. This may take place in steps or stages, if desired. The powdered metal flange may be eliminated or the powdered
6

metal tone ring/flange combination may become two or more pieces assembled or molded as an alternate design.
Still another object of the invention is to provide substantial axial width of the tone ring teeth so the location of the sensor relative to the tone ring accommodates any variation in the stack-up or end play tolerances in the application.
Another object of the invention is to provide a tone ring that will fit over the smallest machined diameter of an axle shaft, leaving larger respective diameters for accommodating the bearings and the oil seal, respectively and allowing the components to be assembled inside the axle tube.
A further object of the invention is to provide a tone ring assembly which inherently allows a desired or correct assembly sequence with the axle shaft, the seal, the bearing and the tone ring. The tone ring assembly can also be reused after disassembly in the field.
An additional object of the invention is to provide a tone ring assembly which will allow passage of oil along one, two paths through the tone ring.
Another object is to provide a textured surface on some or all of the ribs on the tone ring so that these ribs can, in effect, "hold" the oil or grease against the shaft, Ibr ease of, or better lubricated, installation.
A still further object is to use various processes, such as electrical discharge machining (EDM) or Chemical Etching to roughen or create a textured surface on the tooling used to make the rubber part, consequently
7

imparting a textured surface on the inside of the ribs or splines in the finished, molded product.
The invention achieves these objects and others which are inherent therein by providing an assembly which includes a rotatable tone or exciter ring able to generate a varying voltage output by rotation relative to a magnetic sensor, and ribs on its inner diameter, which includes an optional radial flange, optionally an abutting spacer with radial oil passage spaces, a retainer having at least one radial flange, one or more oil passage features, with the associated sensor being adapted to pick up a speed varying signal as the lands or magnets on the tone ring sleeve pass by the sensor.
The manner in which these and other objects of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the present invention set forth by way of example and shown in the accompanying drawings, in which like reference numerals indicate corresponding parts throughou
BRIEF DESCRIPTION OF THE ACCOMPANYIN/REVICE GDRAWINGS
FIG. 1 is a perspective view of one form of the tone ring and the
retainer showing these parts in their assembled condition, and taken from the axially inner end of the tone ring;
FIG. 2 is an exploded fragmentary perspective view of the tone ring assembly of FIG. 1, taken from the axially outer end so as to illustrate the component parts of the retainer, the preferred form of spacer and the various features of these parts and the tone ring;

FIG. 3 is an exploded fragmentary perspective view of the tone ring assembly of FIGS. 1 and 2, and showing the retainer in two parts, and the spacer as well as the tone ring from the axially inner end thereof;
FIG. 4 is a horizontal sectional view of the tone ring assembly, including the retainer, the spacer and the tone ring in their installed positions within the axle housing and over the axle shaft, and showing the seal and bearings in position encircling the shaft;
FIG. 5 is a fragmentary view, with portions broken away, showing an alternate embodiment of the invention; and,
FIG. 6 is a fragmentary view, with portions broken away, showing an embodiment of the invention wherein the sensor is positioned over a window or opening in the retainer.
FIG. 7 is a perspective view looking at the inside of the tone ring and showing a stepped portion on some of the ribs or splines on the inside diameter of the tone ring;
FIG. 8 is a greatly enlarged view of one of the ribs containing the . stepped portion as shown in FIG. 7;.
FIG. 9 is a view taken from the inside of the tone ring body and showing the textured portions on the innermost surfaces of the mounting ribs or splines on the i.d. of the tone ring; and
FIG. 10 is a greatly enlarged view of one portion of one of the ribs of FIG. 9, showing details of its textured surface.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
9

While the tone ring may be embodied in many applications, including automotive and non-automotive applications such as power take-offs, generators and others, a detailed description of the tone ring or exciter ring assembly and its auxiliary components including the detector or sensor will be given first in an application wherein a vehicle drive axle shaft rotates the tone ring, the sensor is located in a fixed position in the axle tube housing just radially outside or removed from the tone ring surface, and an optional flange on the tone ring holds the ring in a fixed position by reason of contact between the flange and a flange of the retainer, preferably with an optional spacer between the tone ring and the retainer.
Referring now to the drawings in greater detail, FIGS. 1-4 show a tone ring assembly generally designated 10, preferably located axially inside the wheel bearing within an axle tube housing assembly generally designated 12, wherein a sensor 14 is held in fixed position within an opening generally designated 16 in the housing assembly 12.
The tone ring body, generally designated 18, includes an axially extending portion 20, a radial flange 22 defined by axially inner and outer surfaces 24, 26 and a radially outermost, stepped surface generally designated 28. The body generally designated 18 includes a radially outer surface generally designated 30 on the axially extending portion 20, the axially inner portion of which is defined by alternately radially extending lands 32 and grooves 34, preferably extending directly purely axially.
The radial flange 22 has a stepped surface 28, having a major diameter surface 35 and a minor diameter surface 36 therein for the axial
10

passage of oil. The inside of the tone ring body 18 includes a rubber portion generally designated 38, and this portion includes a beveled lead-in area 40. In addition, there are plural axially extending ribs 46, each of which includes a lead-in area 44.
The ribs 46 are spaced apart by axially extending grooves 48. The ribs 46 snugly engage the outer diameter 49 of the axle shaft shown as 50, by engaging a portion 52 thereof which is of intermediate size, being slightly larger in diameter than the axially inner portion 53 of the shaft and smaller size than the portiqn 54 engaging the inside diameter 56 of the bearing generally designated 58.
The bearing 58 is shown to include roller elements 60, and an outer retainer 64. The actual type of bearing may vary, and, for example, may feature the rollers 60 indirectly engaging the shaft, or being free from a bearing cage or other locator.
Oil may pass axially through the grooves 48 in the tone ring 18 from the differential (not shown) to the bearings 58 and to the seal generally designated 66. Although not a necessary part of the invention, the seal 66 is shown typically to include a casing or stamping 68 and a rubber primary lip 70. The seal is shown with an auxiliary or dirt lip 71 as is typical with vehicle axles, but this is not strictly necessary.
The tone ring body 18 does not move measurably axially once it is finally installed in the appropriate position over a portion 52 of the shaft 50. In addition to being held by the friction of the ribs 46, the body 18 is also held in a final axial position by a tone ring retainer generally designated 75.
11

Preferably, but not necessarily, the retainer generally designated 75 is made from two components, a thicker gauge radially outer indented casing generally designated 76 and a thinner gauge radially inner casing generally designated 78.
The radially inner casing 78 includes an axially extending portion 80 and a radially inwardly extending retaining flange 82, while the outer casing generally designated 75, into which the inner, thinner casing 80 is pressed, includes a radially inwardly extending retainer flange 83, a generally axially extending portion 84 which includes a corrugated exterior surface portion generally designated 88. Thus, the portion of the casing generally designated 88 includes both raised portions 90 which engage the counterbore 92 and depressed portions 94 which permit axial passage of oil. There are also scalloped cut-outs 97 or relieved areas in the radial flange 83 of the retainer 88. Thus, oil flow may be inside the body 18, or between the tone ring 18 and the retainer 88. The result upon final assembly of the components is a U-shaped retainer in cross-section having flanges 82, 83 which will prevent undesired axial movement of the tone ring body 18 in either direction.
Referring now to another preferred element of the invention, a spacer generally designated 96 is shown to be confined between the radial flange 82 of the inner casing 78 and the axially outer surface 26 of the radial flange 22 of the tone ring 18.
This spacer 96 includes a continuous inner portion 98 and a plurality of teeth 100 separated by spaces 102. Preferably, the teeth 100 include

beveled end portions 104 and flat, axially inner and outer surfaces 106, 108 to facilitate engagement of the radial flange 82 of the radially inner casing 78 and the axially outer surface 26 of the tone ring radial flange 22.
The tone ring body 18 may also have a groove 110 or relieved portion adjacent the radial flange 22 to provide extra clearance between the body 18 and the radial flange 83 of the retainer 75.
Assembling the tone ring with its mating parts is a fairly straightforward operation. The axle shaft 50 includes a smaller diameter portion 53 throughout most of its length. As the axle shaft 50 approaches its axially outer end, however, the diameter is very slightly enlarged as at 52, and the axle shaft 50 includes another step lying toward a larger diameter surface 54 terminating before the flange generally designated 57.
The sensor generally designated 14 is positioned properly relative to the lands and grooves on the tone ring body 18 at this time or later. Since it does not interfere with the tone ring, it can be inserted at any time. The retainer 75 is then placed in the counterbore 92 with a light press fit, while the tone ring body is held within the retainer. The tone ring is held such that it does not tilt excessively, and thus is positioned to receive the axle. No other means is required to guide the axle shaft into position within the body 18. Next, the bearing unit 58 is positioned with its outer retainer 64 pressed into its just larger counterbore 95, and finally, the casing 68 of a seal unit 66 is pressed into the largest counterbore 101.
The axle shaft 50 is then inserted gradually until it engages the tone ring 18 on its inner diameter ribs 46. Then, with the tone ring resisting
13

further inward movement by reason of engagement between the radial flange 83 of the retainer 75 and the tone ring flange surface 24, the axle shaft 50 is pushed gradually axially inwardly (to the right as shown in FIG. 4) until the innermost end of the axle shaft is positioned to receive a C-clip (not shown) for holding the axle shaft in position. Thereafter, the axle shaft is withdrawn axially a few millimeters so the C-clip is properly engaged and seated in the differential. This moves the tone ring slightly to the left as shown in FIG. 4 and insures that the axially outer surfaces 108 of the spacer teeth 100 will engage the retaine&-flange, if necessary, sliding the tone ring body 18 slightly axially inwardly relative to the axle shaft and insuring that the body is properly positioned against spacer 96 which is positioned against retainer flange 82. Thus, the installation is self-aligning and self-centering, which is very desirable. Once the installation is made, another axle shaft may be reinserted in the application by simply pushing it, usually by hand, into place within the tone ring body. Of course, if the original axle shaft were removed, it could be reinserted inside the tone ring.
The materials from which the tone ring are made are conventional for this application. For example, the tone ring itself may be made from a ferrornagnetic^powderedjrie.tal, which is die-formed then sintered into the desired finished form. Other materials may be used, but powdered metal technology may be preferred by reason of its affording relatively deep, square lands and grooves as well as its cost-effective magnetic properties. Metal embedded in plastic can also be used, including magnetic strips laid out
14

axially, and then covered with an elastomer or a plastic material which is permitted to harden.
The rubber used to form the ribs 46 and the surrounding material is an EPDM or other suitable elastomer such as so-called Nitrile (NBR), HNBR, FKM, AEM, ACM or other elastomer. Plastics or thermoset materials can also be used as outlined above in another suitable form. The ribs 46 and surrounding portions 40, 42 of the elastomer may be coated with a dried PTFE material for lubrication, and the substrate may be made from a thermoplastic or thermoset material. For purposes of lubrication, a wet lubricant such as oil, grease or an ammonium alkyl phosphate may be placed on the ID of the tone ring. Both parts of the retainer are preferably made from mild steel but plastic could also be used.
The spacer is an insulating, lubricous material such as Delrin or acetal material, but it possibly could be replaced by a low friction coating on the retainer or on the tone ring flanges, or both, or eliminated completely.
The retainer is fabricated for convenience in two pieces, an inner, thinner piece and an outer, thicker piece, but it could be made in a single piece. The illustrated form has the corrugations in one part of the retainer, which is then combined with a thinner, flat portion to make the radial flanges. The rubber material used in forming the ribs 46 is of the type that will swell in the presence of oil or grease, including oils with extreme pressure additives therein. Consequently, when the tone ring is installed over the axle, it may be located easily, but after the tone ring has been in
15

place for a time, the oil further swells the rubber and the tone ring is held much more firmly in place.
As alternate designs, one may also provide several other constructions. In one such construction, which would be the simplest of these, and is illustrated in Fig. 5, the tone ring generally designated 18a could simply not have the radial flange, which now affords the simplest way for the retainer to insure that the tone ring does not excessively move axially on the shaft during installation. Instead, there is a groove 110a in the body 20a of the tone ring 18a, and a flange 82a extending into the groove 110a. In such a construction, the axial extent of the tone ring would be much larger than the axial extent of the retainer in the first embodiment, but the counterbore 92a would have the axial flange 80 pressed into it. The sensor 14a rests in an opening 16a. In this way, a unitized construction would also be provided.
Another alternate construction is shown in Fig. 6. Here, there is no groove or flange, but the retainer 78b is allowed to span the entire axial length of the tone ring with both flanges 82b, 82b thereby confining the body 18b against the axial movement. In such a construction, of course, it would be necessary to provide an opening or window 99 in one portion of the retainer so that the sensor 14b could function properly.
As previously indicated, the spacer may be eliminated, and in its place, a lubricous coating could be placed on the face of the radial flange 26 of the body, or on the inner face of the flange 82, or both. This expedient could be used in the interest of ultimate cost savings, particularly where

there would be little or no risk of significant axial movement of the tone ring after installation, that is, during operation. In the further alternative, the spacer could be made of a hard grease block material, thereby being adapted to dissolve after significant contact with the radial flange of the body and the radial flange of the retainer.
It is important that there be at least one axial oil passage in the assembly, and preferably, several passages. The most advantageous way of providing these passages is to space the tone ring body apart from the axle shaft by a series df^shallow ribs, and then also provide passages in the spacer, the retainer, and in the tone ring flange4which periodically come into registration to allow the passage of oil through the part. These are useful ways to provide lubrication to the bearings with oil traveling from the differential.
It is sometimes thought advantageous for ease of axle shaft installation that the inside diameter of the tone ring be especially adapted to slip more readily over the shaft, without however, compromising the ability of the tone ring inside diameter (I.D.) to swell in the presence of oil and hence tightly grip the shaft. This may be done in two different ways, merely by way of example.
Referring now to FIGS. 7 and 8, there is shown a modified tone ring generally designated 200 and a retainer generally designated 275. The other features of the tone ring, such as its spaced apart lands and grooves on its O.D., etc. are identical to its earlier shown embodiments. It is only in the construction of the rib 246 that a difference occurs. Here, the rib itself,
17

about halfway along its extent, contains a reduced diameter portion generally designated 247 having a generally flat inwardly directed contact surface 250 and tapered entry and exit surfaces 248, 249. The surface 250 is offset from the remainder of the rib 246, typically about ten thousandths of an inch. (0.010 inches). The surface 250 is about 5 mm or 200 thousandths (0.200 inches) long. Typically, every third rib 246 contains one raised portion 247, although more or fewer ribs 246 may each have a raised portion 247.
In use, the portions 247 of the ribs 246 in some cases render the tone ring easier to install. This is because only the raised portions 247 are in contact with the shaft during installation. However, when the grease or oil on the shaft has an opportunity to react with the rubber, the rubber expands and secures the tone ring in a more fully locked position relative to the axle shaft. The design of the portion is such that it includes two tapered areas 248 and 249 which protect the raised portions from damage during installation, and accommodate axial movement during installation. As pointed out, once the oil or grease reacts with the rubber, the ribs 246 are more securely locked in place.
Another manner of achieving the same effect is illustrated in FIGS. 9 and 10. Here, the tone ring generally designated 300 is identical in all respects with its counterpart shown in FIGS. 1-3, for example. The only exception to this identity is in the construction of the ribs generally designated 346. The spaces between the ribs 48 are identical, and the
18

makeup of the modified, textured ribs 346 is the only difference in these tone rings.
Here, the surface designated 350 contains a texture. The surface thus contains a series of generally flat portions lying in a plane, but also contains a very large number of smaller portions 354 having an indented or textured random pattern. The pattern shown in FIG. 10 is merely for illustration, it being understood that the portions with the slightly enlarged diameter or countersunk portions are from 2 to 10 thousandths of an inch (0.002 -0.010), preferably about 5 or 6 thousandths (0.005 - 0.006 inches). The manner of making this pattern in the molded rubber part is relatively simple. The electrical discharge machining (EDM) anode tip used to form the rib geometry on the molding tool is designed to be very rough, and as a result, the tooling used to make the rubber products in this area takes on a rough, textured appearance. Consequently, the rubber that is formed or molded in this tooling has a mirror image impression of the texture on the molding tool. Consequently, the ribs generally designated 350 take on a textured character on their inner surface. This texturing can alternately be achieved by chemical "etching" of the subject tool area. For example, acid is used in selected areas to create "pockets" similar to the EDM approach.
When it comes to installing these units, the textured portion creates "pockets" to hold the residual oil or grease against the shaft. Consequently, these "packets" hold lubricant and effectively create a film thickness of lubricant between the rubber and the shaft. This, in theory reduces the installation force.

Consequently, this more lubricated construction may in some cases be preferred for ease of installation, especially bearing in mind that the axle shaft is made to a certain tolerance, which may be larger or smaller by a few thousandths of an inch.
The simplest application of the tone ring assembly would be for use in
controlling speeds of a single shaft, for example, a generator shaft. However,
a more typical use of the tone ring and its associated parts is with two wheel
drive vehicles, where the feedback from the sensor is sent to a computer g
which then determines relative velocities of the two axles. For example, _ A ,u
such a use would be in ABS systems (anti-lock braking systems), and I ,-A^\ tSf*Y
differential control systems. M*
The tone rings are most advantageously used in four wheel drive systems, where the speed of each axle is desired to be governed by a computer having four or more inputs. Thus, the tone rings are useful, not only in various braking systems, but also in traction control systems where front wheel versus rear wheel speeds must be determined instantaneously, and where right versus left wheel speeds may be also measured instantaneously and then corrected, according to the design of the system.
It will thus be seen that the present invention provides an improved tone ring assembly having a number of advantages and characteristics including those expressly pointed out herein, and others which are inherent in the invention. A few embodiments of the product of the invention, having been shown and described, it is anticipated that variations to the described form of apparatus will occur to those skilled in the art and that such

modifications and changes may be made without departing from the spirit of the invention or the scope of the appended claims.
21a

WE CLAIM
1. A tone rhg assembly 10 for use on a rotatable machine part 50, said
assembly comprising tone ring 18 able to generate a varying voltage
output when rotated at varying speeds, with a fixed magnetic sensor
assembly 14 disposed in facing relation and closely spaced from said tone
ring 18, said rotatable machine part 50 having an axially inner portion 53
and an axially output portion 54 running in a surrounding bearing unit 58,
said tone ring 18 comprising an aiiafy extending main body portion 20
win a pluraity of areas 30 able to generate a voltage output upon
rotation, a retailer 75 having at least one radial flange 82 to prevent
substantial axial movement of said tone ring 18, said tone ring 18
comprising plural axially extending rtos 46 of reduced diameter on its
Inner diameter for snugly engaging a rotating machine part, and having
axial spaces of enlarged diameter 48 between said rbs 46, thereby
affording passages for oil to pass axially said tone ring assembly 10.
2. A tone ring assembly as claimed in claim 1, whereh said tone rhg body
20 comprises a plurality of axialy extending lands 32 and grooves 34
therein.
3. A tone ring assembly as claimed in claim 1, whereh said tone ring body
20 comprises a pbrality of magnetic strips arranged fri an axially
extending formation and spaced circumferenSalty apart from each other.
4. A tone ring assembly as claimed in claim 1, wherein said toe ring body 20
comprises a radial flange 22 formed on the axially outer end thereof.
21

5. A tone ring assembly as claimed in claim 1, whereri said at least one
radial flange 82 on said retainer comprises two rediaf flanges.
6. A tone ring assembly as darned in claim 1, wherein said retainer 75 is
comprised of two pieces, a radial Inner retaher portion 83 of generafly L-
shaped and a radially outer retainer portion portion 82 of generally L-
shape, both portions being combined to form a U-shaped assembly having
axially inner and outer radial flanges.
7. A tone ring assembly as claimed ii claim 6, wherein said retainer 75 is a
metal retainer made from two separate elements pressed and locked
together.
8. A tone ring assembly as claimed In claim 7, wherein said radially outer
portion 82 of said retainer 75 Is made from a thicker gauge of metal than
said radially inner portion 83 of said retainer 75.
9. A tone ring assembly as claimed in claim 1, wherein said retainer 75 in
made from a thermoplastic or thermoset plastic material.
10. A tone ring assembly as claimed fri claim 1, wherein said axially extending
rtos 46 on the hner diameter of said tone rng assembly 10 have beveled
end portions 44 so as to facilitate hstallatton over said rotating machine
part.
11. A tone ring assembly as claimed h claim 1, comprising a spacer 96, tying h use between one end of said ring 18 and one flange 82 or 83 of said retainer 75, said spacer 96 being made from a low friction material which Is resistant to noise making when h at least occasional contact with said tone ring 18.
22-

12. A tone ring assembly as claimed h claim 1, wherein said at least one
radial flange 82 of said retaher 75 comprises an axialiy hwardty feeing
flange 80 on said retainer coated win an antt-frlctton material.
13. A tone ring assembly as claimed h claim 11, wherein said tone ring body
20 comprtshg a radial flange portion 22 adapted to engage a radial
retainer flange 83, said radial flange 22 on said body 20 having areas of
different diameters, with relief areas on said radial retainer flange 83, said
spacer 96 having plural separate teeth 100 thereon, said teeth being
engage able by an axialfy outer radial flange 80 of said retainer, thereby
altowhg the passage of oil through the relief areas and said teeth areas.
14. A tone rrig assembly as claimed to claim 11, wherein said spacer 96 is
made from a plastic material.
15.A tone ring assembly as claimed in claim 11, wherein said spacer 96 is made at least in part from a hard grease block.
16. A tone ring assembly as claimed in claim 4, comprishg a low friction
coating material on the ax tally outermost portion 26 of said radial flange
22 on said tone ring body 20.
17. A tone ring assembly as claimed fri claim 4, whereh said radial flange 22
of said tone rhg body 20 is an assembled metal flange made from a
different material than the reminder of said tone rtig body.
18. A tone rtig assembly as claimed h claim 11, wherein said spacer 96 is
discontinuous at its outer diameter to permit oil flow axialty therethrough.
23

19. A tone ring assembly as claimed in claim 1, wherefc said rbs 46 of said
tone ring 20 comprises an elastomer that is a blend of NBR and EPDM.
20. A tone rrig assembly as claimed in claim lr wheren said ribs 46 on said
tone rhg 20 comprise at least one elastomer selected from (he class
consisting of NBR, HNBR, B>DM, AB1 and ACM.
21. A tone ring assembly as claimed in claim 1, wherein said liner diameter of
said tone ring 20 comprises a coating of dried PTFE.
22. A tone ring assembly as claimed in claim 1, whereh said rbs 46 on said
Inner diameter of said tone ring 78 are made from a thermoplastic or
thermoset material.
23. A tone ring assembly as claimed h claim 1, whereh said inner diameter of
said tone ring comprises a wet lubricant coatrig selected from the class
consisting of oil material, grease materials and ammonium afcyl
phosphates.
24. A tone ring assembly as claimed h claim 4, whereh said radial flange 83
of said retainer 75 Includes cut-out portions 97 to permit oil to pass
therethrough.
25. A tone ring assembly as claimed in claim 4, wherein said tone ring body
20 has, on said flange 22 thereof, a stepped diameter 35, 36.
26. A tone ring assembly as claimed n claim 4, wherein said tone ring 18
comprises an air gap lying between radially opposed portions of said tone
ring body 20 and said radial flange 22 of said tone ring body for allowance
24

of maximum axle shaft deflection without touching the flanges 82,83 on said retainer 75.
27. A tone ring assembly as claimed in claim 1, comprising one of a removed
rotating machine part SO, said axle shaft, and a separate axle shaft
installed into the orlgfrial toe and retainer assembly.
28. A tone ring assembly as claimed ii claim 4, wherein said tone ring
assembly is installable over an axle shaft 50 and held in place by
interference between said tone riig body 20 and said flanges 82,83 on
said retainer 75 durhg the entfre sequence of ^stalling the axle shaft 50.
29. A tone riig assembly as claimed h clakn 5, wherein said flanges 82,83, on
said retainer 75 engage a radial flange 22 on said tone ring body 20 and
provide a self-aligning feature and self-centering feature.
30. A tone ring assembly as claimed in claim 5, wherein said flanges 82,83 on
said retainer 75 provide for accommodating axel tolerances stacked up in
the assembly of the axle shaft.
31. A tone ring assembly as claimed In claim 1, whereh said retainer 75 has
two radial flanges 82,83 and spans the axial width of the entire tone ring,
said retainer 75 havhg an opening in at least one part of the axial extent
thereof for receiving the sensor.
32. A tone riig assembly for use on a rotatable machhe part 50, said
assembly 10 comprising a rotatable machine part 50, said assembly 10
comprises a rotatable tone ring 18 able to generate a voltage output by
rotation ad a magnetic sensor assembly 14 disposed in facing relation and
closely spaced from said tone rhg 18, said rotatable machine part 50
25

having an axialty inner portion 53 and an axially outer portion 54 running in a surrounding bearing unit 58 and with oil leakage being resisted by an oil seal 66, said tone ring comprfehg an axlally extending main body portion 20 with a plurality of lands 32 and grooves 34, which generate a votage outage output upon rotation, and a radially extending flange 22 at one end of said tone ring 18, a retainer 75 having axlafty liner 83 and outer 82 radial flanges to prevent substantial axiat movement of said tone ring, and a spacer 96 tying between said radialy extending flange 22 on said tone ring 18 and said axially outer radial flange 82 of said retainer 75, said tone ring having plural radially extending rbs 46 on its inner diameter for snugly engaging said rotatable machine part 50, the spaces 48 between said rbs 46 affordhg passages for allowing oil to pass axlalty through said tone ring 18.
33. A tone ring assembly as claimed h claim 32, comprising a groove 110a in
said tone rhg body 20a lying between said flange 22 and tie remainder
of said body 20a, said groove 110a receiving one of said axial flanges 82a
of said retainer 75 ad preventing axial movement of said body 20a.
34. A tone rhg assembly for use on a rotatable machhe part 50, said
assembly comprising a rotatable tone ring 18 able to generate a voltage
output by rotation and a magnetic sensor assembly 14 disposed in facing
relation and closely spaced from said tone ring 18, said rotatable machine
part 50 having an axlalty inner portion 53 and an ax tatty outer portion 54
running in a surrounding bearing unit 58 and with oil leakage being
resisted by an oil seal 66, said tone ring 18 comprising an axiafly
extendhg main body portion 20 with a plurality of lands 32 and grooves
34 able to generate a votage output upon rotation and a radialy
extendhg flange 22 at one end of said tone rhg 18, a retainer 75 havfcig
axlalty inner 83 and outer 82 radial flanges to prevent substantial axial
26

movement of said tone ring 18, said tone ring having means permfcting passage of oil ax tally along said tone ring as well as means for engaging said rotatabie machine part 50 to locate said tone ring on said rota table machine part 50r said engaging means alkmiig said rotatabie machine part ad said tone ring to become more strongly adherent when said tone ring Is exposed to an oily condition.
35. A tone ring assembly as claimed ft claim 34, wherein said body portion 20
of said tone ring and said retainer 75 are so sized that upon Installation
of said retainer ft the application counterbore, said body portion 20 is
supported by said retainer 75, and presents an op en frig ft the ftslde
diameter thereof that ts able to be aligned without addUonal aid with an
axle shaft which is to be ftserted therethrough.
36. A tone ring assembly as claimed ft claim 34, whereh said flanges 82,83
on said retainer 75 permit said body to move ax tally inwardly ft one
direction during installation to expose an axle dp, and to move ft the
opposite direction to a position engaging said other axial flange through
said spacer.
37. A tone ring assembly as claimed ft claim 1, wherein said tone ring body
20 is made from a powdered metal material, and wherein said radial
flange ts made from a material other than that comprising said tone ring
body.
38. A tone ring assembly as claimed ft claim 37, whereft said tone ring body
20 fe made from a powdered metal material and said radial flange 82 or
83 is made from a stamped metal material.
27

39. A tone ring assembly as claimed h claim 37, wherein said tone ring body
is made from a powdered metal, material and said radial flange 82 or 83
Is made from a plastic material.
40. A tone ring assembly as claimed In claim 1, wherein at least one of said
axialty extending rbs 246 of reduced diameter comprises a first portion
and a second portion 250, said second portion 250 being of reduced
diameter so as to initially engage said rotatable machine part 50 only and
said first portion thereafter being adapted upon contact with oil and
grease more into snug engagement with said rotatable machine part.
41. A tone rhg assembly as claimed fei claim 40, whereto said atfeast one of
saW ribs 246 comprises plural rbs,
42. A tone rtog assembly as claimed to claim 40, whereh every third rib
comprises said second portion 250.
43. A tone ring assembly as claimed to claim 1, whereto at least one of said
axially extending rfes 246 comprises a portion factog said rotatable
machine part 50, said portion having a large plurality of asperities and
therefore a large plurality of pockets for fcibrleant.
44. A tone ring assembly as claimed to claim 43, whereto said at least one rto
246 comprises plural rbs.
45. A tone rtog assembly as claimed to claim 44, whereh every third rto
comprises said second portion 250.
28

46. A tone ring assembly as claimed h claim 44, wherein at least one rfo 246 is formed by moldiig in a mold havitg surface asperities formed by electrical discharge machining or Chemical Etehhg.
This invention relates to a tone ring assembly for use on a rotatable machine part. The tone ring (10) is able to generate a varying voltage output when rotated at varying speeds. A fixed position magnetic sensor detects the voltage. The tone ring comprises an axially extending main body portion (18) having a plurality of areas able to generate a voltage upon rotation. A retainer (75) having at least one radial flange (82,83) prevents axial movement of the tone ring (10) and the tone ring includes ribs (46) and spaces (48) on its inside diameter to permit oil to pass therethrough.

Documents:

00703-kolnp-2003 abstract.pdf

00703-kolnp-2003 claims.pdf

00703-kolnp-2003 correspondence.pdf

00703-kolnp-2003 description(complete).pdf

00703-kolnp-2003 drawings.pdf

00703-kolnp-2003 form-1.pdf

00703-kolnp-2003 form-13.pdf

00703-kolnp-2003 form-18.pdf

00703-kolnp-2003 form-2.pdf

00703-kolnp-2003 form-26.pdf

00703-kolnp-2003 form-3.pdf

00703-kolnp-2003 form-5.pdf

00703-kolnp-2003 letters patent.pdf

703-KOLNP-2003-FORM 27.pdf

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Patent Number

205272

Indian Patent Application Number

703/KOLNP/2003

PG Journal Number

13/2007

Publication Date

30-Mar-2007

Grant Date

30-Mar-2007

Date of Filing

02-Jun-2003

Name of Patentee

SKF USA INC.

Applicant Address

900 N STATE STREET, ELGIN, IL 60123, U.S.A. A US COMPANY.

Inventors:

#	Inventor's Name	Inventor's Address
1	DOBBS, DAVID	15000 BAINBRIDGE LIVONIA, MI 48154 U.S.A.
2	SPREITZER, MARK	30950 star trail milford, mi 48381
3	BULLARD, MORGAN	573 WARNER STREET HAMPSHIRE, IL 60140 U.S.A.
4	FAUSETT, WAYDE	4330 E. LAKE SHORE DRIVE WONDER LAKE, IL 60097 U.S.A.

PCT International Classification Number

G 01 P 3/48

PCT International Application Number

PCT/US02/34759

PCT International Filing date

2002-10-30

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10/012,880	2001-11-02	U.S.A.
2	10/161,437	2002-06-03	U.S.A.