Title of Invention

CLAMPING DEVICE OF DISC BRAKE

Abstract

(57) Abstract: A clamping devide (28) of a disc brake (10), in particular ~ sliding caliper spot-type disc brake or a reaction beam spot-type disc brake for trucks or buses, comprises at least one plunger (46) which is movable in the direction of a plunger axis (C) in order to apply a brake lining (22) to a brake disc and at last one eccentric (38) which is rotatable about a transverse axis (B) for the actuation of the brake and is supported in at least one roller bearing (40) . A rolling body (44) is supported at the eccentric (38) by means of a bearing shell (42) for the trans mission of actuation forces to the plunger (46). To avoid prone-to-wear conditions within the clamping device, the bearing shell (42) comprises an exten¬sion (78) which, relative to the transverse axis (B), pro¬jects at least approximately radially outwards and is adapted for engagement with a cage (84) of the roller bearing (40) and which can return the cage (84) into a defined initial position upon release of the brake. PRICE: THIRTY RUPEES

Full Text

' * The invention relates to a clamping device of a disc brake, in particular to a sliding caliper spot-type or a reaction beam spot-type disc brake for trucks or buses, comprising at least one plunger which is movable in the direction of a plunger axis in order to apply a brake lining to a brake disc, at least one eccentric which is movable about a transverse axis and which is supported in at least one roller bearing, and a rolling body which is supported on the eccentric by means of a bearing shell to transmit operating forces to the plunger. Such a clamping device is known from DE 42 12 406 Al. In order to allow the roller bearing supported eccentric to rotate in as wear-free a manner as possible it is necessary that the cage which retains the rolling bodies of the roller bearing follows the rotational movement of the eccentric and is not fixed in any manner prior to completion of the rotational movement of the eccentric. Such a fixing may occur, for example, if the angle of rotation which the roller bearing cage can cover is limited, e.g. by stops. If the cage abuts a stop before completion of the rotational movement of the eccentric, a sliding friction between the surfaces of the rolling bodies and the roller bearing supported eccentric surface will result which is prone to wear. In the case of eccentrics which are supported by split bearing shells, it was found that the angle of rotation of the eccentric can be larger during actuation of the clamping device than during releasing of the brake so that the cage of the roller bearing will no longer be able to completely follow the rotational movement of the eccentric upon another acutation of the brake. The invention is based on the object to further develop a generic clamping device in such a manner that the prone-to-wear conditions mentioned can no longer occur. At the same time, the design and the assembly of a generic clamping device are to be simplified. This object is solved according to the invention in that the bearing shell, which supports the rolling body at the ec¬centric, is provided with an extension which projects at least approximately radially to the outside relative to the transverse axis of the eccentric, which is formed so as to engage a cage of the roller bearing, and which can return the cage into a defined initial position when the brake is re¬leased. If the roller bearing cage does not reach this initial position by itself upon releasing the brake, i.e. upon reversal of the eccentric, a forced coupling between the radial extension of the bearing shell and at least one cage,of the roller bearing will be effected according to the invention so that the cage of the roller bearing will be returned into a defined initial position, regard less of whether the angle of rotation of the eccentric during the brake release operation is smaller than during actuation of the brake, from which it is able to completely follow a subsequent rotational movement of the eccentric in the course of a new brake actuation cycle. It should be noted that the described travel differences of the roller bearing cage, which can occur between a movement in the direction of application and a movement in the direction of release, are very small and often are within the range of a few thousandths of a millimeter. However, such minute travel differences accumulate over thousands of braking operations of a brake under actual operating conditions and result in a considerable bearing shift which, for the above mentioned reasons, is undesirable. If the roller bearing which supports the eccentric comprises several cages, the extension of the bearing shell which pro¬jects radially outwards is preferably designed according to the invention in such a way that it can engage the several cages of the roller bearing, which are arranged adjacent to each other, in order to commonly return all cages of a roller bearing into the defined initial position. Alternatively, the cages arranged adjacent to each other can also be coupled to each other so that it would be sufficient that the radial extension of the bearing shell engages only one of the cages. If the eccentric is supported in several roller bearings, it must be ensured that each roller bearing is returned into the defined initial position. This can be achieved, for example, by several exten¬sions projecting radially outwards which are formed at a bear¬ing shell, or several bearing shells are provided, each of which has one or several radial extensions. According to a preferred embodiment of the clamping device according the the invention, the roller bearing has a cylinder sector shape, and the radial extension of the bearing shell engages with a free longitudinal edge of the roller bearing cage or cages upon release of the brake. The roller bearing which supports the eccentric is preferably a needle bearing, and in particular a two-row needle bearing. In order to ensure the permanent exact return of the roller bearing or its cage or cages, respectively, into the defined initial position, the bearing shell with the radial extension is fixed at the eccentric. Preferably, the bearing shell is se¬cured at the eccentric against a displacement in an axial direction and against a rotation about the transverse axis of the eccentric by means of a positive connection. In a particularly preferred embodiment of the clamping device according to the invention, securing of the bearing shell both against a displacement in the axial direction as well as against rotation is effected by means of an embossment at the side of the eccentric, which extends into a recess, in parti¬cular of a blind hole shape, in the eccentric. The embossment is made by the impact of a suitable embossing tool on the inner surface of the bearing shell. In preferred embodiments of the clamping device according to the invention, the radial extension of the bearing shell is formed in such a way that it is integral with it, for example by means of a lug which is integrally connected with the bear¬ing shell. If several radial extensions are provided at one bearing shell then all these extensions are preferably formed integrally with the bearing shell. The bearing shell can be manufactured in a simple manner, for example from a commercially available coated sheet by punching and forming, including the radial extension or extensions. In order to secure the rolling body which is supported at the eccentric by means of the bearing shell, the bearing shell pre¬ferably comprises one or several projections which extend radially inwards from the face end edge of the bearing shell. The projections which extend radially inwards from the face end edge can be formed integrally with the bearing shell, e.g. as one bent sheet metal lug each, in the same raanner as the extension or extensions of the bearing shell which extend radially outwards. ' The bearing shell of the rolling body is also essentially of a hollow cylinder sector shape and covers an area of more than 180°, but less than 200°. It is thus achieved that the rolling body can be pressed into the bearing shell during assembly without difficulty and does not drop out of the bearing shell again easily. In the following, an embodiment of the invention is described in more detail with reference to the accompanying drawings, in wh i ch: Fig. 1 is a partially sectioned plan view of a brake disc with a clamping device according to the invention; Fig. 2 is a cross-section of the clamping device of Fig. 1; Fig. 3 is a portion of Fig. 2 in an enlarged representa¬tion; Fig. 4 is the view IV from Fig, 3; and Fig. 5 is the section V-V from Fig. 4. A spot-type disc brake 10 shown in Figs. 1 and 2 is associated with a brake disc (not shown) which is rotatable about an brake disc axis A and comprises a brake support 12, along which a reaction beam 14 is guided for a movement parallel to the axis A. Two sleeves 16 serve as guides, each of which is fastened by one hexagon socket screw 18 each to the support 12, and are protected against contamination by means of bellows 20. The reaction beam 14 encompasses two brake linings 22 and 24 which can be applied to one side each of the brake disc (not shown) .and which conventionally comprise one lining back plate each, on the side of which facing the brake disc one layer each of friction material is attached. For the actuation of the disc brake 10 a clamping device 28 which is arranged in a housing 26 is provided which comprises a lever-type actuating member 30 (see Fig. 2). The free end of the actuating member 30 is provided with a recess 32 into which a rod-shaped or plunger-shaped output member (not shown) engages for the actuation of the brake in order to pivot the actuating member 30 in a clockwise direction (relative to Fig. 2). The output member can, for example, be a part of a conventional pneumatic diaphragm cy1inder and therefore a detailed explanation can be omitted. The lever-type actuating member 3 0 is formed integrally with a rotary body 34 which is arranged in the housing 26 of the clamping device 28 and rotatable about a transverse axis B which intersects the brake disc axis A perpendicularly. The rotary body 34 comprises a central portion 36 between two eccentrics 38, each of which is supported in a cover 41 of the housing 26 by means of one cylinder sector or shell-shaped roller bearing 40 each. Each roller bearing 40 is adapted as a two-row needle bearing. At each of the two eccentrics 3 8 a roller body 44 is supported by means of a bearing shell 42 (see Figs. 3 to 5) the axis of which extends parallel to the transverse axis B. The two eccentrics 38 are assigned one each of two plungers 46 each of which has a plunger axis C which extends parallel to the brake disc axis A and intersects the transverse axis B perpendicularly and which are arranged symmetrically with respect to a centre plane of the clamping device 28, which contains the brake disc axis A and extends normal to the transverse axis B. Each of the two plungers 46 consists of one sleeve-shaped plunger part 48, one bolt-shaped plunger part 50 and a cap 52. The two sleeve-shaped plunger parts 4S are supported in one sliding sleeve 54 each which are press-fitted in the housing 26 so as to be movable along and rotatable about their plunger axis C, and are provided with a female thread ' each by means of which they are screwed on a complementary male thread of the associated bolt-shaped plunger part 50. The two caps 52 are clearance-fitted in the associated sleeve-shaped plunger part 48 and comprise one flat end face each which faces away from it and extends normally to the plunger C against which the roller body 44 is in rolling contact. The two sleeve-shaped plunger parts 48 carry one ring gear 56 each which is fastened to it and which meshes with a gear 58. The gear 58 is supported rotatably about an axis parallel to the plunger axes C at a central plate 60, which axially bears against the two ring gears 56 and is loaded by a return spring 62. This is installed between the central plate 60 and the housing 26 to be biased in such a manner that it keeps the two plungers 46 via their caps 52 in continuous contact with the roller bodies 44. The two bolt-shaped plunger parts 50 project axially from the sleeve-shaped plunger parts 48 and the sliding sleeves 54 where they have a considerably increased diameter and are connected to each other in such a manner that they cannot rotate by means of a thin metal plate 64 which simultaneously serves as a heat shield. The just described portion of the clamping device 28 represents an actuating arrangement generally designated as 65. The illustrated clamping device 28 is additionally provided with an adjusting device generally designated as 66 the centre axis D of which is arranged parallel to the plunger axes c. The adjusting device 66 serves to automatically restore the original value of the brake slack which is increased during operation due to wear of the friction material attached to the brake linings 22, 24, i.e. the distance between each brake lining and the brake disc in the non-actuated condition of the brake. For this purpose, the adjusting device 66 which, similar to the two eccentrics 38, bears against the housing cover 4l of the clamping device 28 is connected with the rotary body via a V-drive (angular drive) 68. The special design of the adjusting device 66 and the V-drive 68 connecting same with the actuating arrangement 65 is of no significance within the scope of the • herein described invention so that a detailed explanation is omitted. Upon actuation of the brake 10 the rotation of the rotary body 34, which is caused by pivoting the actuating member 30, is converted by the two eccentrics 38 to a translation movement of the two plungers 4 6 whereby the brake lining 22 is pressed against the brake disc (not shown). Because each of the two eccentrics 38 bears against the housing cover 41 via its roller bearing 40, the reaction force which is generated as soon as the brake lining 22 contacts the brake disc and is pressed against it, is transmitted via the housing cover 41 to the housing 26 or the reaction beam 14, respectively, and causes the reaction beam 14 to be slidably moved alongs its sleeves 16 which urges the brake lining 24 against the brake disc. With reference to Figs. 2 to 5, the support of the rolling bodies 44 as well as the eccentric 38 will now be explained in more detail. Each bearing shell 42 which in the present embodiment is made from a commercially available coated sheet by punching and forming is located at the associated eccentric 38 by means of an embossment 70 which protrudes at the outer surface of the bearing shell 42 at the side of the eccentric and is in positive engagement with a blind hole 72 formed in the eccentric. The embossment ?o thus protects the bearing shell 42 both against a displacement in an axial direction, i.e. axially parallel to the transverse axis B as well as against rotation in a circumferential direction. Each bearing shell 42 has an essentially hollow cylinder sector shape and covers a range of approx. 200°. The cylindrical rolling body 44 can thus be pressed even more easily into the bearing shell 42 and is properly retained in the bearing shell 42 due to the extension of the bearing shell over more than 180°. In order to prevent the cylindrical rolling body 44 which is suported in the bearing shell 42 from being displaced outwardly in the direction of the transverse axis B, several projections 7 6 wh ich extend rad i a 11 y i nwards are provided at a face pnd edge 74 of the bearing shell 42, which are formed integrally with the bearing shell. The two rolling bodies 44 are prevented from being displaced axially inwards, i.e. towards the central plane of the clamping device 28, by the central portion 36 of the rotary body 34. For resetting the roller bearing 40 which supports the eccen¬tric 38, each bearing shell 42 comprises an extension 78 which extends radially outwards and is also integrally formed with the bearing shell 42 and which is tapered at its free end at 80 in order to be able to engage a neighbouring free longitudinal edge 82 of a roller bearing cage 84 upon reversal of the eccentric 38, i.e. upon upon the release of the brake. As can be seen from Fig. 4, the width of the tapered,,portion 80 of the extension 78 of the bearing shell 42 is so selected that it can engage the two roller bearing cages 8 4 of the roller bearing 4 0 for resetting same. As can be seen, particularly from Figs. 3 to 5, each extension 78 with its tapered portion 80 can press against the free longitudinal edges 82 of the two roller bearing cages 84 of each roller bearing 40 upon pivoting back the rotary body 34 together with the two eccentrics 38 connected with same so that said cages are forced to return into their initial position. The initial position of each roller bearing cage 84 is defined by the free angle of rotation 0 which, with the brake completely released, is included between an upper stop 88 of a roller bearing shell 87 and the extension 78 of the bearing shell 42 (see Fig. 3). It is to be taken into consideration that a small clearance should be provided between a lower stop 86 of the roller bearing shell 87 and the roller bearing cage 8 4 in order to prevent an excessive pressure from being applied to the roller bearing cage 84 upon its resetting. Upon a new actuation of the brake by pivoting the actuating member 30 in a clockwise direction the full distance S between the free longitudinal edge 82 and the upper stop 88 of the roller bearing shell 87 is thus available for a displacement of the roller bearing cages 84 from the so defined initial position. The angle of rotation Q which is covered when passing through the distance S corresponds to approximately half the pivoting angle through which the actuating member 30 and thus the rotary body 34 are rotated during an actuation with maximum actuation iorce (see also Fig. 2). * We Claim 1. A clamping devide (28) of a disc brake (10) in particular a sliding caliper spot-type disc brake or a reaction beam spot-type disc brake for trucks or buses, comprising at least one plunger (46) which is movable in the direction of a plunger axis (C) in order to apply a brake lining (22) to a brake disc; at least one eccentric (38) which is rotatable about a transverse axis (B) for the actuation of the brake and is supported in at least one roller bearing (40); and a rolling body (44) which is supported at the eccentric (38) by means of a bearing shell (42) for the transmission of actuation forces to the plunger (46), characterized in that the / bearing shell (42) comprises an extension (78) which, relative to the transverse axis (B), projects at least approximately radially outwards and is adapted for engagement with a cage (84) of the roller bearing (40) and which can return the cage (84) into a defined initial position upon release of the brake. 2. The clamping device according to Claim 1, wherein the radially extending extension (78) of the bearing shell (42) of the rolling body (44) is designed for an engagement with several cages (84) of the roller bearing (40) arranged adjacent to each other. 3. The clamping device according to Claim 1 or 2, wherein the roller bearing (40) is of a cylinder sector shape and the extension (78) comes into engagement with a free longitudinal edge (82) of the roller bearing cage (84) upon relase of the brake. 4. A clamping device according to any one of the preceding claims, wherein the bearing shell (42) of the rolling body (44) is positively secured at the eccentric (38) against displacement. 5. A clamping device according to any one of the preceding claims, wherein the bearing shell (42) of the rolling body (44) is positively secured at the eccentric (38) against rotation about the transverse axis (B). 6. A clamping device according to claims 5 and 6, wherein securing of the bearing shell (42) against displacement in an axial direction and against rotation is achieved by means of an embossment (70) of the bearing shell (42) on the eccentric side, which extends into a preferably blind hole shaped recess (72) in the eccentric (38). 7. A clamping device according to any one of the preceding claims, wherein the bearing shell (42) of the rolling body (44) comprises one or several projections (76) which extend radially inwards from the face end edge (74) of the bearing shell and secure the rolling bodies (44) against an exial displacement. 8. A clamping device according to Claim 1, wherein each projection (76) is formed by an lug which is integral 1y connected with the bearing shell (42). 9. A clamping device substantially as herein described with reference to the accompanying drawings and as claimed in any of the claims.

Documents:

810-mas-1996 others.pdf

810-mas-1996 abstract.pdf

810-mas-1996 assignment.pdf

810-mas-1996 claims.pdf

810-mas-1996 correspondence others.pdf

810-mas-1996 correspondence po.pdf

810-mas-1996 description (complete).pdf

810-mas-1996 drawings.pdf

810-mas-1996 form-1.pdf

810-mas-1996 form-13.pdf

810-mas-1996 form-26.pdf

810-mas-1996 form-4.pdf

810-mas-1996 form-6.pdf

810-mas-1996 pct.pdf

810-mas-1996 petition.pdf