Title of Invention

MAGNET PUMP IMPELLER SUPPORTING STRUCTURE

Abstract

A magnet pump impeller supporting structure comprises : a housing main body (A1) having a shaft attachment portion (2) located in the center of the impeller chamber (1) ;an impeller shaft (5) having a large- diameter shaft portion (5a) and a small-diameter shaft portion (5b), the large-diameter shaft portion being mounted in the shaft attachment portion (2); and an impeller (B) having a bearing portion (B1) in which a tapered bearing hole (7a, 7b) is formed, and which has an inner magnet disposed around the bearing portion, wherein the impeller shaft extends through the bearing hole and is supported by sliding supporting portions in two locations along the axial direction of the tapered bearing hole (7a, 7b).

Full Text

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet pump impeller supporting structure which makes it possible to form two sliding-supporting locations in the axial direction of the bearing in a shaft and bearing hole which are used to support an impeller on which an inner magnet is mounted so that the impeller is free to rotate inside a pump chamber, with no particular working of the bearing hole and only slight working of the shaft, so that axial oscillation of the impeller can be prevented, thus allowing rotation in a stable state and reducing costs. 2. Description of the Related Art In the past, there have been magnet pumps which have an impeller and inner magnet that are supported so that these parts are free to rotate on a shaft that is fastened to the casing side. For example, the structure described in Japanese Utility Model Publication No. S63-29906 may be cited as one example of such a magnet pump impeller supporting structure. 1A In this utility model, respective bearings are disposed on both end portions (with respect to the axial direction) of the inner magnet of the impeller, and the impeller is supported on a shaft via these bearings so that the impeller is free to rotate. In this impeller supporting structure, bearings which have a single straight hole diameter, i. e., the same diameter in the direction of the hole, are supported so that these bearings are free to rotate on a shaft which has a single straight shaft diameter, i. e., the same diameter in the axial direction. Thus, structures in which bearings with a single straight hole diameter are disposed on a shaft with a single straight shaft diameter also include structures in which bearings are disposed separately on both end portions (with respect to the axial direction) of the impeller and inner magnet, and structures in which bearings are disposed singly in the axial direction of the impeller and magnet. The abovementioned impeller and inner magnet must be supported on a shaft that is fastened to the casing side so that the impeller and inner magnet are free to rotate in a stable state. Accordingly, since it is necessary to suppress oscillation of the impeller and inner magnet with respect to the axial center, a long bearing is disposed in the axial direction of the impeller and inner magnet, or bearings are disposed separately 2 on both end portions so that the length is increased in the axial direction. However, in cases where a single long bearing is disposed in the axial direction of the impeller and inner magnet, the bearing hole as a whole must have a straight hole diameter formed by extremely high-precision working with respect to the straight shaft diameter which is formed by high-precision working of the entire length of the shaft. Accordingly, finishing must be performed with extremely high precision in order to ensure that the clearance of the overall rotational sliding surfaces between the shaft and the single bearing is maintained in an appropriate range. As a result, the working costs are increased, so that such a structure cannot easily be used. On the other hand, in the case of an embodiment in which respective separate bearings are disposed on both end portions of the impeller and inner magnet with respect to the axial direction, there is no need for the working of a long straight hole diameter in the axial direction as there is in the case of the abovementioned embodiment in which a single bearing is disposed; accordingly, bearings which have a short axial length can be used, and the working of a straight hole diameter is facilitated. However, since bearings are used in two locations, the axial centers of the two bearings must he 3 precisely aligned. Furthermore, the number of parts required is also increased, and an assembly process is required, so that it becomes difficult to lower the cost. SUMMARY OF THE INVENTION Thus, in the case of single bearings or split bearings, it has been necessary to work a straight hole diameter with a high degree of precision regardless of whether the material used is a metal material, synthetic resin material or the like. An object of the present invention is to prevent the difficulty of manufacture and increase in cost that result from an increase in the working precision and assembly precision of the abovementioned bearings. Accordingly, diligent research was conducted in order to solve the abovementioned problems. As a result, it has been discovered that stable impeller rotation can be realized in the present invention without high-precision finishing of the hole in the bearing part with respect to the impeller shaft by constructing a magnet pump impeller supporting structure according to the present invention. To overcome the above problems, the present invention provides a magnet pump impeller supporting structure comprising : a housing main body in which a shaft attachment portion is formed in a central location of the impeller chamber ;an impeller , 4 shaft in which a large - diameter shaft portion and a small-diameter shaft portion are formed in the same axial direction, and the side of said large-diameter shaft portion is mounted in said shaft attachment portion and an impeller which has a bearing portion in which a tapered bearing hole is formed, and which has an inner magnet disposed around said bearing-portion, wherein said impeller shaft extends through said tapered bearing hole and is supported by sliding supporting portions in two locations along the axial direction of said tapered bearing hole. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 (A) is a partially sectional side view of a magnet pump using the present invention ; Fig. 1 (B) is an exploded perspective view of the impeller chamber, impeller and partially cut-away partition wall body ; Fig. 2 is a longitudinal-sectional side view showing a state in which the impeller is mounted on the impeller shaft; Fig. 3 is a partially sectional side view showing a state in which the impeller shaft is mounted in the shaft attachment portion ; Fig. 4 is a longitudinal-sectional side view of the impeller; Fig. 5 is an enlarged view including a sectional view which shows a state in which the impeller shaft is inserted into the tapered bearing hole ; 5 Fig. 6 is an enlarged constitutional diagram showing a fluid flowing into the gap between the impeller shaft and the tapered bearing hole; Fig. 7 is a longitudinal-sectional side view of the essential parts of the present invention using an impeller shaft of the type in which the shaft step portion is near the flange-form portion; Fig. 8 (A) is a longitudinal-sectional side view of the construction of the impeller shaft and bearing portion with a tapered bearing hole unified into a single part in the axial direction; and Fig. 8 (B) is a longitudinal-sectional side view of the impeller and bearing portion with a tapered bearing hole unified into single part in the axial direction. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the attached figures. First to describe the construction of the magnet pump, the pump housing A is constructed mainly from a housing main body A1 and a partition wall body A2. As is shown in Fig. 1 (A) and Fig. 1 (B), a substantially circular impeller chamber 1 is formed in this housing main body A1, and a shaft attachment portion 2 for the impeller shaft 5 (described later) is formed in the central position of the impeller chamber 1. Furthermore, an intake 6 port 3 and a discharge port 4 are formed in the abovementioned impeller chamber 1. The abovementioned partition wall body A2 is mounted facing the impeller chamber 1 of the abovementioned housing main body A1, and is a part that accommodates the impeller B together with the impeller chamber 1. As is shown in Fig. 1 (B), the external shape of the abovementioned partition wall body A2 is substantially hat-shaped, and is constructed from a connecting portion 12 and a partition wall main body 11 which comprises a cover portion l1b that covers the abovementioned impeller chamber 1 and a cylindrical accommodating portion 11a that can accommodate the inner magnet 9 of the impeller B. As is shown in Fig. 1 (A) and Fig. 1 (B), the abovementioned connecting portion 12 is formed with a circular circumferential shape that allows insertion inside the inner circumferential surface la of the abovementioned housing main body A1. A grooved ridge 12a into which a sealing member 13 such as an O-ring or the like can be inserted is formed [in the connecting portion 12], and the impeller chamber 1 can be formed into a watertight structure with the outside part of the pump via the sealing member 13 when the partition wall body A2 is mounted in the housing main body A1. 7 Next, in the abovementioned impeller shaft 5, a large-diameter shaft portion 5a and a small-diameter shaft portion 5b are formed in a continuous configuration in the axial direction; furthermore, as is shown in Fig. 3, a flange-form portion 5c is formed on the other end of the large-diameter shaft portion 5a (i. e., the opposite end from the abovementioned small-diameter shaft portion 5b), and a shaft-fastening portion 5d is formed from the flange-form portion 5c. This shaft fastening portion 5d is a part which is attached to the shaft attachment portion 2 formed on the side of the abovementioned housing main body A1, and the abovementioned flange-form portion 5c acts as a stopper with respect to the shaft attachment portion 2. The abovementioned shaft fastening portion 5d is mounted and fastened in place by being press -fitted in the shaft attachment portion 2. The abovementioned large-diameter shaft portion 5a and small-diameter shaft portion 5b are connected via a shaft step portion 5e, and this shaft step portion 5e is formed so that it steps down from the large-diameter shaft portion 5a to the small-diameter shaft portion 5b (see Fig. 3). Furthermore, there is a relatively slight difference between the diameter D1 of the large-diameter shaft portion 5a and the diameter D2 of the small-diameter shaft portion 5b. 8 Next, as is shown in Fig. 1 (A) and Fig. 1 (B), the impeller B is constructed from a vane portion 10, a magnet accommodating portion 6, an inner magnet 9 and a bearing part B1. The bearing portion B1 is formed from a synthetic resin material, non-magnetic metal material or the like. A tapered bearing hole 7 is formed in the center [of the bearing portion B1] in the axial direction. The taper of the tapered bearing hole 7 may be formed at the time of molding. The tapered bearing hole 7 is formed from a large-diameter tapered hole portion 7a and a small-diameter tapered hole portion 7b; the large-diameter tapered hole portion 7a and small-diameter tapered hole portion 7b are located on the same axial center along the axial direction, with the abovementioned large-diameter tapered hole portion 7a and small-diameter tapered hole portion 7b being divided by a step portion 7c. As is shown in Fig. 4, Fig. 5 and other figures, the step portion 7c is formed so that it steps down from the abovementioned large-diameter tapered hole portion 7a to the small-diameter tapered hole portion 7b. The abovementioned bearing portion B1 is formed by the injection molding of a synthetic resin material; the tapered bearing hole 7 is molded "as is" by the pull-out taper of a center pin inside the mold. Furthermore, a flange portion 8a is formed on one end (with respect to the axial direction) of 9 the cylindrical portion 8 of the bearing portion B1, and an engaging groove 8b is formed in the other end. When the impeller B is molded from a synthetic resin material, the inner magnet 9 is insert-molded. The abovementioned bearing portion B1 is mounted and fastened in the central portions of the impeller B and inner magnet 9. The through-hole of the inner magnet 9 is positioned in the central area of the vane portion 10 of the impeller B. The abovementioned bearing portion B1 is inserted into this through-hole, and the inner magnet 9 is fastened in the axial direction by a snap ring (circlip) which is mounted in an engaging groove 8b located on the opposite end of the bearing portion B1 from the flange portion 8a. Furthermore, the fastening of the bearing portion B1 and inner magnet 9 with respect to the rotational direction is accomplished by means of a bonding agent. The abovementioned tapered bearing hole 7 is formed so that the hole diameter varies from the intermediate portion in the axial direction via the step portion 7c. The reason for this is as follows: specifically, even if the length of the bearing portion B1 in the axial direction is increased, the opening portion of the small-diameter tapered hole portion 7b can be made smaller in the case of a large-diameter tapered hole portion 7a which is formed by disposing a step portion 7c 10 that is larger than the maximum diameter of the small-diameter tapered hole portion 7b in the intermediate portion of the bearing portion B1 than in the case of a large-diameter tapered hole portion 7a which is formed with a single taper along the entire axial direction of the bearing portion B1. Accordingly, an appropriate clearance can be obtained without expanding the clearance with the impeller shaft 5 having a straight shaft diameter portion consisting of a large-diameter shaft portion 5a and a small-diameter shaft portion 5b. As a result of the use of the abovementioned construction, the tapered bearing hole 7 (large-diameter tapered bearing hole 7a, small-diameter tapered bearing hole 7b) formed during the molding of the abovementioned bearing portion B1 can be used "as is" as the bearing sliding surface with the impeller shaft 5. The sliding surfaces P2 between the small-diameter tapered hole portion 7b of the abovementioned bearing portion B1 and the small-diameter shaft portion 5b of the impeller shaft 5, and the sliding surfaces P1 between the large-diameter tapered hole portion 7a of the bearing portion B1 and the large-diameter shaft portion 5a of the impeller shaft 5 act as sliding supporting portions in two locations along the axial direction of the bearing portion B1; accordingly, the impeller B can be supported so that the impeller is free to rotate, and firm support can be obtained so that oscillation in the direction of the axial center can be suppressed (see Fig. 5). 11 Since both sliding surfaces P1 and P2 described above can be obtained as sliding supporting portions in two locations that are separated by a specified interval in the axial direction of the bearing portion B1 the length of the bearing portion B1 in the axial direction can be increased, so that oscillation of the impeller B can be suppressed. Furthermore, since the length of the abovementioned bearing portion B1 in the axial direction can be increased, the length of the abovementioned inner magnet 9 in the axial direction can also be correspondingly increased in accordance with the bearing portion B1, so that the magnetic pole area of the magnetic coupling accomplished by means of a transmission mechanism via the magnetic force between the inner magnet 9 and an outer magnet (not shown in the figures) can be increased. Accordingly, the transmitted rotational force can be increased. Furthermore, a gap is formed between the large-diameter shaft portion 5a and small-diameter shaft portion 5b of the impeller shaft 5 and the abovementioned tapered bearing hole 7; a fluid flows into the gap, and this fluid acts as a lubricant. In Fig. 6, the flow of the fluid that flows into the abovementioned gap is indicated by arrows. In particular, since the fluid flows in to the location of the step portion 7c formed between the large-diameter tapered hole portion 7a and small-diameter tapered hole portion 7b of the tapered hole 12 portion 7, the effect of the fluid as a lubricant in the vicinity of both sliding surfaces P1 and P2 is increased, so that the impeller B can rotate smoothly. Furthermore, the shaft step portion 5e of the impeller shaft 5 is formed at a substantially central point on the shaft portion that passes through, so that the lengths of the large-diameter shaft portion 5a and small-diameter shaft portion 5b are substantially the same; however, this shaft step portion 5e may also be formed at a point that is closer to the root end of the large-diameter shaft portion 5a (see Fig. 7). In this way, the interval between the sliding surfaces P1 and P2 can be increased, so that the rotation of the impeller B can be stabilized. Furthermore, Fig. 8 shows a type in which no step portion 7c is formed in the tapered bearing hole 7, so that a bearing hole with a single tape is the axial direction is formed. The synthetic resin material used to form the bearing portion B1 of the impeller B, and also to form the impeller itself, was a polyphenylene sulfide (PPS). However, other synthetic resin materials may also be used depending on the conditions of use of the pump, so that the present invention is not limited to this material. Furthermore, the abovementioned inner magnet 9 rotates along with the rotation of an outer magnet (not shown in the figures) which is disposed on the outside of the 13 accommodating portion 11a of the abovementioned partition wall portion A2; as a result, the impeller B rotates. Thus, the present invention provides a magnet pump impeller supporting structure comprising a housing main body A1 in which a shaft attachment portion 2 is formed in a central location of the impeller chamber 1, an impeller shaft 5 in which a large-diameter shaft portion 5a and a small-diameter shaft portion 5b are formed in the same axial direction, and the side of the large-diameter shaft portion 5a is mounted in the abovementioned shaft attachment portion 2, and an impeller B which has a bearing portion B, in which a tapered bearing hole 7 is formed, and which has an inner magnet 9 disposed around the bearing portion B1, wherein the abovementioned impeller shaft 5 is passed through the abovementioned tapered bearing hole 7 and supported by sliding supporting portions P1 and P2 in two locations along the axial direction of the tapered bearing hole 7. Accordingly, the following effects are obtained : specifically, sliding supporting points can be disposed at two locations in the axial direction of the bearing merely by applying a slight degree of working to the shaft, without any need for high-precision working of the tapered bearing hole 7 formed in the bearing portion B of the impeller B, so that axial oscillation of the impeller can be suppressed, thus making it possible to stabilize the rotational support of the impeller shaft 5, and therefore to reduce costs. 14 To describe the abovementioned effect in detail, in cases where a bearing portion B1 consisting of a synthetic resin is used, a magnet pump impeller supporting structure is used in which the tapered bearing hole 7 formed by the pull-out taper during molding is disposed "as is" as the bearing hole, the impeller B is fastened in this bearing hole, and the impeller shaft 5 equipped with a shaft step portion 5e is fastened by being press-fitted in the housing main body A1. Accordingly, when the impeller shaft 5 which comprises a large-diameter shaft portion 5a and small-diameter shaft portion 5b is passed through the tapered bearing hole 7, the respective shaft end portions of the large-diameter shaft portion 5a and small-diameter shaft portion 5b are supported in two appropriately separated locations in the tapered bearing hole 7, so that a stable rotational state can be obtained. As a result, there is no need for high-precision finishing on the side of the tapered bearing hole 7 formed in the bearing portion B1 of the abovementioned impeller B ; this tapered bearing hole 7 can be used "as is", so that the manufacturing costs and manufacturing time can be reduced. In one embodiment of this invention, the step portion 7c is formed in the tapered bearing hole 7 of the abovementioned bearing portion B1 in an appropriate. 15 location in the hole direction, and a large-diameter tapered hole portion 7a and small-diameter tapered hole portion 7b are formed with the step portion 7c interposed therebetween. Accordingly, as a result of a large-diameter shaft portion 5a and a small-diameter shaft portion 5b being disposed on the impeller shaft 5 via a shaft step portion 5e, without any working of the tapered bearing hole 7 of the bearing portion B1, the contact surfaces of the large-diameter shaft portion 5a and large-diameter tapered hole portion 7a form sliding surfaces P1, and the contact surfaces between the small-diameter shaft portion 5b and the small-diameter tapered hole portion 7b form contact surfaces P2, so that support is obtained in these two places. Consequently, axial oscillation of the impeller B is suppressed, so that the impeller B can be caused to rotate in a stable state. Furthermore, there is no increase in the number of parts required, and the cost can be reduced. In another embodiment, the shaft step portion 5e formed between the large-diameter shaft portion 5a and the small-diameter shaft portion 5b of the abovementioned impeller shaft 5 is positioned in a substantially intermediate location on the impeller shaft 5 with respect to the axial direction of the impeller shaft 5. Accordingly, the flow of a fluid into 16 the space between the tapered bearing hole 7 and the large-diameter shaft portion 5a and the small-diameter shaft portion 5b is facilitated, and this fluid acts as a lubricant, so that smooth rotation of the impeller B can be achieved. Lastly, in a further embodiment, the shaft step portion 5e formed between the large-diameter shaft portion 5a and the small-diameter shaft portion 5b of the abovementioned impeller shaft 5 is positioned closer to the root end of the large-diameter shaft portion 5a. Accordingly, the distance between the sliding surfaces P1 and P2 where the impeller shaft 5 and tapered bearing hole 7 contact each other can be increased, so that the rotation of the impeller B can be stabilized.. 17 WE CLAIM : 1. A magnet pump impeller supporting structure comprising : a housing main body (A1) in which a shaft attachment portion (2) is formed in a central location of the impeller chamber (1); an impeller shaft (5) in which a large- diameter shaft portion (5a) and a small-diameter shaft portion (5b) are formed in the same axial direction, and the side of said large-diameter shaft portion is mounted in said shaft attachment portion (2); and an impeller (B) which has a bearing portion (B1) in which a tapered bearing hole (7a, 7b) is formed, and which has an inner magnet (9) disposed around said bearing portion, wherein said impeller shaft extends through said tapered bearing hole and is supported by sliding supporting portions (P1, P2) in two locations along the axial direction of said tapered bearing hole. 2.The magnet pump impeller supporting structure as claimed in claim 1, wherein a step portion (7c) is formed in said tapered bearing hole in an appropriate location in the hole direction, and a large-diameter tapered hole portion (7a) and a small-diameter tapered hole portion (7b) are formed with said step portion interposed therebetween. 18 3.The magnet pump impeller supporting structure as claimed in claim 1 or 2, wherein the shaft step portion (5e) formed between the large-diameter shaft portion (5a) and the small-diameter shaft portion (5b) of said impeller shaft (5) is positioned in a substantially intermediate location on the impeller shaft with respect to the axial direction of the impeller shaft. 4The magnet pump impeller supporting structure as claimed in any one of claims 1 to 3, wherein the shaft step portion (5e) formed between the large-diameter shaft portion (5a) and the small-diameter shaft portion (5b) of said impeller shaft is positioned closer to the root end of the large-diameter shaft portion. 19 5 A magnet pump impeller supporting structure, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. A magnet pump impeller supporting structure comprises : a housing main body (A1) having a shaft attachment portion (2) located in the center of the impeller chamber (1) ;an impeller shaft (5) having a large- diameter shaft portion (5a) and a small-diameter shaft portion (5b), the large-diameter shaft portion being mounted in the shaft attachment portion (2); and an impeller (B) having a bearing portion (B1) in which a tapered bearing hole (7a, 7b) is formed, and which has an inner magnet disposed around the bearing portion, wherein the impeller shaft extends through the bearing hole and is supported by sliding supporting portions in two locations along the axial direction of the tapered bearing hole (7a, 7b).

Documents:

00581-cal-2001-abstract.pdf

00581-cal-2001-claims.pdf

00581-cal-2001-correspondence.pdf

00581-cal-2001-description(complete).pdf

00581-cal-2001-drawings.pdf

00581-cal-2001-form-1.pdf

00581-cal-2001-form-18.pdf

00581-cal-2001-form-2.pdf

00581-cal-2001-form-3.pdf

00581-cal-2001-form-5.pdf

00581-cal-2001-g.p.a.pdf

00581-cal-2001-letters patent.pdf

00581-cal-2001-priority document others.pdf

00581-cal-2001-priority document.pdf

581-CAL-2001-CORRESPONDENCE.pdf

581-CAL-2001-FORM 27-1.1.pdf

581-CAL-2001-FORM 27.pdf

581-CAL-2001-FORM-27-1.pdf

581-CAL-2001-FORM-27.pdf