Constant velocity universal joint

Abstract

To provide a constant velocity universal joint that can reliably suppress electromagnetic noise. [Solution] The sliding constant velocity universal joint 3 comprises an outer joint member 31, an inner joint member 32 arranged on the inner circumference of the outer joint member 31, a roller unit 33 that transmits torque between the outer joint member 31 and the inner joint member 32, a shaft 4 with one end connected to the inner joint member 32, and a boot 34 fitted between the outer joint member 31 and the shaft 4. Within the seal space S2 surrounded by the outer joint member 31 and the boot 34, an electromagnetic noise suppression member 5 including a magnetic material 51 is provided on the outer circumferential surface of the shaft 4.

Description

Technical Field

[0001] The present invention relates to a constant velocity universal joint.

Background Art

[0002] In recent years, from the viewpoint of reducing environmental impact, electric vehicles such as battery electric vehicles (BEV), fuel cell vehicles (FCV), hybrid vehicles (HEV), plug-in hybrid vehicles (PHEV), etc., which run using all or part of electric energy as power, have been widely used.

[0003] The powertrain of this type of electric vehicle includes components that can be electromagnetic noise sources such as batteries and e-modules (motors and inverters). Therefore, electric vehicles are required to take measures against electromagnetic noise generated due to electromagnetic noise sources, specifically, to improve EMC (electromagnetic compatibility).

[0004] Thus, for example, Patent Document 1 discloses providing soft ferrite on a dynamic damper mounted on the outer peripheral surface of a shaft of a drive shaft. In this document, it is said that by providing soft ferrite on the dynamic damper in this way, the generation of radio noise caused by electromagnetic waves radiated from the shaft can be prevented due to the magnetic loss effect of the soft ferrite.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] A drive shaft typically comprises an outboard (outer side in the vehicle width direction) constant velocity universal joint, an inboard (center side in the vehicle width direction) constant velocity universal joint, and an intermediate shaft connecting both constant velocity universal joints. The dynamic damper is generally installed in the middle of the intermediate shaft that protrudes outside the boots of both constant velocity universal joints so as not to affect the function of both universal joints.

[0007] On the other hand, electromagnetic noise sources such as batteries and e-modules are typically located in the center of the electric vehicle (on the inboard side of the drive shaft).

[0008] Therefore, when soft ferrite is provided in a dynamic damper, as in Patent Document 1, it is difficult to place the soft ferrite close to the electromagnetic noise source, and there is a risk that electromagnetic noise cannot be sufficiently suppressed.

[0009] The object of this invention is to provide a constant velocity universal joint that can reliably suppress electromagnetic noise. [Means for solving the problem]

[0010] (1) The present invention, devised to solve the above problems, is a constant velocity universal joint comprising an outer joint member, an inner joint member disposed on the inner circumference of the outer joint member, a torque transmission member that transmits torque between the outer joint member and the inner joint member, a shaft with one end connected to the inner joint member, and a sealing device installed between the outer joint member and the shaft, characterized in that an electromagnetic noise suppression member containing a magnetic material is provided on the outer surface of the shaft within the sealed space surrounded by the outer joint member and the sealing device.

[0011] In this way, the magnetic material of the electromagnetic noise suppression component can be placed in close proximity to electromagnetic noise sources such as batteries and e-modules. Therefore, electromagnetic noise can be reliably suppressed by the magnetic material.

[0012] (2) In the configuration of (1) above, it is preferable that the constant velocity universal joint is provided on the inboard side of the drive shaft.

[0013] In the case of a drive shaft, electromagnetic noise sources such as batteries and e-modules are located on the inboard side. Therefore, by applying the present invention to a constant velocity universal joint provided on the inboard side of the drive shaft, the magnetic material of the electromagnetic noise suppression member can be positioned sufficiently close to the electromagnetic noise source on the inboard side, thereby reliably suppressing the generation of electromagnetic noise.

[0014] (3) In the configuration of (1) or (2) above, it is preferable that the outer diameter surface of the electromagnetic noise suppression member is an inclined surface that approaches the inner diameter side as it moves from one end of the shaft to the other end opposite to the other end.

[0015] In this way, even if the operating angle of the constant velocity universal joint increases, the electromagnetic noise suppression member is less likely to interfere with other components such as the boot or outer joint member. In other words, even with the electromagnetic noise suppression member installed, the performance of the constant velocity universal joint can be maintained at a good level.

[0016] (4) In any of the configurations described in (1) to (3) above, it is preferable that the electromagnetic noise suppression member is provided on the outer surface of the shaft located within the seal space, at a position closer to the inner joint member.

[0017] In this way, even if the operating angle of the constant velocity universal joint increases, the electromagnetic noise suppression member is less likely to interfere with other components such as the boot or outer joint member. In other words, even with the electromagnetic noise suppression member installed, the performance of the constant velocity universal joint can be maintained at a good level.

[0018] (5) In any of the configurations described in (1) to (4) above, it is preferable that the magnetic material is provided so as to surround the entire circumference of the outer surface of the shaft.

[0019] In this way, a high electromagnetic noise suppression effect can be obtained from the magnetic material of the electromagnetic noise suppression member.

[0020] (6) In any of the configurations (1) to (5) above, it is preferable that the electromagnetic noise suppression member is positioned by fitting into a recess or a protrusion provided on the outer peripheral surface of the shaft.

[0021] In this way, the electromagnetic noise suppression member can be easily and surely attached to the outer peripheral surface of the shaft.

[0022] (7) In any of the configurations (1) to (6) above, it is preferable that the electromagnetic noise suppression member has an elastic body between the magnetic body and the outer peripheral surface of the shaft.

[0023] In this way, it becomes difficult to form a gap between the magnetic body and the outer peripheral surface of the shaft. As a result, the mounting state of the magnetic body with respect to the shaft becomes stable, and thus a stable countermeasure against electromagnetic noise becomes possible.

[0024] (8) In any of the configurations (1) to (7) above, it is preferable that the shaft has a minimum diameter portion where the shaft diameter is the smallest within the seal space, and the electromagnetic noise suppression member is provided on the outer peripheral surface of the minimum diameter portion.

[0025] The suppression effect of electromagnetic noise by the magnetic body is improved by reducing the inner diameter of the magnetic body and increasing the cross-sectional area. On the other hand, if the electromagnetic noise suppression member is provided on the outer peripheral surface of the minimum diameter portion of the shaft, the inner diameter of the magnetic body can be reduced. In addition, since the space outside the outer peripheral surface of the shaft expands, it becomes easy to increase the cross-sectional area of the magnetic body while avoiding interference between the electromagnetic noise suppression member and other members such as boots and outer joint members. Therefore, according to the above configuration, the suppression effect of electromagnetic noise by the magnetic body can be improved.

[0026] (9) In any of the configurations (1) to (8) above, it is preferable that the magnetic body is a ferrite core.

[0027] In this way, a high suppression effect of electromagnetic noise can be obtained.

Advantages of the Invention

[0028] According to the present invention, a constant velocity universal joint that can reliably suppress electromagnetic noise can be provided. [Brief explanation of the drawing]

[0029] [Figure 1] This is a partial cross-sectional view of the drive shaft according to this embodiment. [Figure 2] This is a magnified cross-sectional view showing the constant velocity universal joint on the inboard side of the drive shaft in Figure 1 when it is not operating at an angle. [Figure 3] Figure 1 is a cross-sectional view showing an enlarged view of the constant velocity universal joint on the inboard side of the drive shaft in its operating angle position. [Figure 4] This is a cross-sectional view AA in Figure 2. [Figure 5] This diagram illustrates the procedure for attaching an electromagnetic noise suppression member to the outer surface of a shaft. [Figure 6] This is a cross-sectional view corresponding to the AA cross-sectional view in Figure 2, showing a modified example of the electromagnetic noise suppression member. [Figure 7] This is a cross-sectional view corresponding to the AA cross-sectional view in Figure 2, showing a modified example of the electromagnetic noise suppression member. [Modes for carrying out the invention]

[0030] Embodiments of the present invention will be described below with reference to the drawings.

[0031] Figure 1 shows a drive shaft 1 installed in an electric vehicle. The drive shaft 1 comprises a fixed constant velocity universal joint 2 installed on the outboard side, a sliding constant velocity universal joint 3 installed on the inboard side, and an intermediate shaft 4 (hereinafter simply referred to as "shaft 4") connecting the two constant velocity universal joints 2 and 3. One end of shaft 4 is on the inboard side, and the other end opposite to the one end of shaft 4 is on the outboard side. Furthermore, the sliding constant velocity universal joint 3 and shaft 4 described above constitute a constant velocity universal joint according to one embodiment of the present invention.

[0032] The outboard fixed constant velocity universal joint 2 is of the Zeppa type and includes an outer joint member 21, an inner joint member 22, a plurality of balls 23 as torque transmission members, a retainer 24, and a boot 25 as a sealing device.

[0033] Multiple ball tracks are formed by multiple track grooves 21a formed on the inner spherical surface of the outer joint member 21 and multiple track grooves 22a formed on the outer spherical surface of the inner joint member 22, with one ball 23 placed in each ball track. Torque is transmitted at a constant speed between the outer joint member 21 and the inner joint member 22 via the balls 23, while allowing angular displacement. The boot 25 is fixed between the outer circumferential surface of the outer joint member 21 and the outer circumferential surface of the shaft 4 by tightening it with boot bands 25a and 25b. Grease is sealed in the seal space S1 surrounded by the outer joint member 21 and the boot 25 as a lubricant. The stem portion 21b of the outer joint member 21 is connected to the wheel via a wheel bearing (not shown). Note that the fixed constant velocity universal joint 2 is not limited to the above, and may be an undercut-free type or a cross-groove type, for example.

[0034] The inboard sliding constant velocity universal joint 3 is of the tripod type (the illustrated example is a double-roller type tripod), and includes an outer joint member 31, an inner joint member (tripod member) 32, a plurality of roller units 33 as torque transmission members, and a boot 34 as a sealing device.

[0035] A roller unit 33 is arranged on the outer circumference of three leg shafts 32a provided on the inner joint member 32. The roller unit 33 includes an inner ring 33a, an outer ring 33b, and needle rollers 33c positioned between the two rings 33a and 33b. The roller unit 33 (outer ring 33b) is positioned in a plurality of track grooves 31a formed on the inner circumferential surface of the outer joint member 31. Torque is transmitted at a constant speed between the outer joint member 31 and the inner joint member 32 via the roller unit 33, while allowing angular and axial displacements. The boot 34 is fixed between the outer circumferential surface of the outer joint member 31 and the outer circumferential surface of the shaft 4 by tightening it with boot bands 34a and 34b. Grease is sealed in the seal space S2 surrounded by the outer joint member 31 and the boot 34 as a lubricant. The stem portion 31b of the outer joint member 31 is connected to a differential device (not shown). The sliding constant velocity universal joint 3 is not limited to the above; for example, it may be a tripod type with a single roller or one using a ball as a torque transmission member (such as a double offset type).

[0036] Male splines are formed on the outer circumference of both ends of the shaft 4. Female splines are formed on the inner circumference of the inner joint member 22 of the fixed constant velocity universal joint 2, and female splines are formed on the inner circumference of the inner joint member of the sliding constant velocity universal joint 3. The male splines of the shaft 4 engage (spline-fit) with the female splines of the inner joint members 22 and 32 of the respective constant velocity universal joints 2 and 3, thereby connecting them in a way that enables torque transmission.

[0037] The shaft 4 has a minimum diameter portion 41 at the shaft end located within the seal space S2 of the sliding constant velocity universal joint 3 provided on the inboard side, where the shaft diameter (outer diameter) is smallest. The shaft 4 also has a maximum diameter portion 42 at the middle of the shaft located outside the seal space S2 of the sliding constant velocity universal joint 3 provided on the inboard side, where the shaft diameter (outer diameter) is largest. Note that the shaft 4 is not limited to the above shape. For example, the shaft 4 may have a portion at the shaft end located within the seal space S1 of the fixed constant velocity universal joint 22 provided on the outboard side that has the same diameter as the minimum diameter portion 41. Alternatively, for example, the portion corresponding to the minimum diameter portion 41 and the portion corresponding to the maximum diameter portion 42 may have the same diameter.

[0038] As shown in Figures 2 to 4, an electromagnetic noise suppression member 5 is provided on the outer circumferential surface of the smallest diameter portion 41 of the shaft 4 located within the seal space S2 of the sliding constant velocity universal joint 3. The electromagnetic noise suppression member 5 has a magnetic material 51. In this way, the magnetic material 51 of the electromagnetic noise suppression member 5 can be placed in close proximity to components that could become sources of electromagnetic noise located on the inboard side of the drive shaft 1 (for example, batteries or e-modules). Therefore, electromagnetic noise (for example, radio noise, etc.) can be reliably suppressed by the magnetic material 51. In addition, since the electromagnetic noise suppression member 5 is placed within the seal space S2, the volume within the seal space S2 is reduced, and the amount of grease to be sealed can also be reduced.

[0039] Here, the magnetic material 51 suppresses electromagnetic noise, for example, by a current limiting effect due to high impedance and / or by a noise energy consumption effect due to magnetic loss. The electromagnetic noise suppression effect of the magnetic material 51 can be improved by reducing the inner diameter of the magnetic material 51 and increasing its cross-sectional area. Therefore, in this embodiment, the inner diameter of the magnetic material 51 is reduced by providing an electromagnetic noise suppression member 5 on the outer circumferential surface of the smallest diameter portion 41 of the shaft 4. In this case, it also becomes easier to make the cross-sectional area of ​​the magnetic material 51 relatively large.

[0040] The magnetic material 51 is composed of, for example, a ferrite core (preferably nickel-zinc (Ni-Zn) ferrite). The material of the magnetic material 51 is not particularly limited as long as it can suppress electromagnetic noise. The magnetic material 51 may be, for example, silicon steel, permalloy, Sendust, Permendur, etc.

[0041] The magnetic material 51 forms a ring shape that surrounds the entire circumference of the outer surface of the shaft 4 (see Figure 4). In other words, the magnetic material 51 is continuous around the entire circumference of the shaft 4.

[0042] The electromagnetic noise suppression member 5 further includes an elastic body 52 interposed between the magnetic body 51 and the outer circumferential surface of the smallest diameter portion 41 of the shaft 4. This makes it difficult for a gap to form between the magnetic body 51 and the outer circumferential surface of the shaft 4. As a result, the mounting state of the magnetic body 51 to the shaft 4 becomes stable.

[0043] In this embodiment, the elastic body 52 is provided not only between the magnetic body 51 and the outer circumferential surface of the smallest diameter portion 41 of the shaft 4, but also to cover the entire surface of the magnetic body 51. In other words, the magnetic body 51 is embedded inside the elastic body 52 and integrated with the elastic body 52.

[0044] The elastic body 52 is made of, for example, rubber (preferably vulcanized rubber). However, the material of the elastic body 52 is not particularly limited. The elastic body 52 may be made of, for example, resin.

[0045] The electromagnetic noise suppression member 5 is positioned on the outer circumferential surface of the smallest diameter portion 41 of the shaft 4, near the inner joint member 32 (specifically, near the position where the inner joint member 32 and the shaft 4 are spline-fitted), by a protrusion 41a provided on the outer circumferential surface of the smallest diameter portion 41 (see Figures 2 and 3). In detail, the elastic body 52 engages with the protrusion 41a, restricting the axial movement of the electromagnetic noise suppression member 5. This allows the electromagnetic noise suppression member 5 to be easily and reliably attached to the outer circumferential surface of the shaft 4. Alternatively, a recess may be provided in the smallest diameter portion 41 of the shaft 4, and the electromagnetic noise suppression member 5 may be positioned by engaging the elastic body 52 with the recess.

[0046] The outer diameter surface 5a of the electromagnetic noise suppression member 5 is composed of an inclined surface (tapered surface) that approaches the inner diameter side as it moves toward the outboard side. In this way, as shown in Figure 3, even if the operating angle θ of the sliding constant velocity universal joint 3 becomes large, the electromagnetic noise suppression member 5 is less likely to interfere with other members such as the outer joint member 31 and the boot 34. Therefore, the electromagnetic noise suppression member 5 can prevent a decrease in the function of the sliding constant velocity universal joint 3. It is preferable that the inclination angle of the outer diameter surface 5a of the electromagnetic noise suppression member 5 with respect to the axis of the shaft 4 is less than or equal to the maximum operating angle of the sliding constant velocity universal joint 3 (for example, 26° or less).

[0047] Next, a method for attaching the electromagnetic noise suppression member 5 to the outer circumferential surface of the smallest diameter portion 41 of the shaft 4 will be explained based on Figure 5.

[0048] First, prepare the shaft 4 before the inner joint member 32 of the sliding constant velocity universal joint 3 is connected to one end (inboard side). Next, push the electromagnetic noise suppression member 5 into the shaft 4 from one end.

[0049] The portion 43 including the male spline portion 43a located on the inboard side of the minimum diameter portion 41 of the shaft 4 is a large-diameter portion having an outer diameter (maximum outer diameter) D2 that is larger than the outer diameter D1 of the minimum diameter portion 41 of the shaft 4. However, the outer diameter D2 of the large-diameter portion 43 is smaller than the outer diameter of the maximum diameter portion 42. In the electromagnetic noise suppression member 5, the inner diameter D3 of the magnetic material 51 is larger than the outer diameter D2 of the large-diameter portion 43, and the inner diameter D4 of the elastic material 52 is smaller than the outer diameter D2 of the large-diameter portion 43.

[0050] Therefore, when the electromagnetic noise suppression member 5 is pushed in, the elastic body 52, located between the magnetic body 51 and the outer circumferential surface of the large-diameter portion 43, is compressed outward by the large-diameter portion 43. In this state, when the electromagnetic noise suppression member 5 is pushed in further, when the electromagnetic noise suppression member 5 reaches a predetermined position on the outer circumferential surface of the smallest-diameter portion 41, the elastic body 52 elastically returns to its original shape so as to expand inward. As a result, the electromagnetic noise suppression member 5 is held on the outer circumferential surface of the smallest-diameter portion 41 of the shaft 4. At this time, the recess 52a provided in the elastic body 52 engages with the protrusion 41a provided on the outer circumferential surface of the smallest-diameter portion 41, and the electromagnetic noise suppression member 5 is positioned. In the illustrated example, the large-diameter portion 43 has a tapered portion 43b at the connection point with the smallest-diameter portion 41 that gradually decreases in diameter toward the smallest-diameter portion 41. When the electromagnetic noise suppression member 5 reaches a predetermined position on the outer circumferential surface of the smallest-diameter portion 41, the tapered portion 43b also contacts the elastic body 52, thereby positioning the electromagnetic noise suppression member 5. In other words, in this embodiment, the axial movement of the electromagnetic noise suppression member 5 is restricted by the convex portion 41a and the tapered portion 43b of the shaft 4.

[0051] Furthermore, the present invention is not limited to the configuration of the above embodiments, nor is it limited to the effects described above. The present invention can be modified in various ways without departing from the spirit of the invention.

[0052] In the above embodiment, the magnetic material 51 does not have to be continuous around the entire circumference of the shaft 4. For example, as shown in Figure 6, the magnetic material 51 may be composed of multiple members that are spaced apart in the circumferential direction of the shaft 4. Alternatively, as shown in Figure 7, the magnetic material 51 may be composed of a single member in which only a part of the circumferential direction of the shaft 4 is discontinuous, and the remainder is continuous around the shaft 4 (for example, a C-shape when viewed along the axial direction). However, from the viewpoint of suppressing electromagnetic noise, it is preferable that the magnetic material 51 is ring-shaped and surrounds the entire circumference of the outer surface of the smallest diameter portion 41 of the shaft 4.

[0053] In the above embodiment, the electromagnetic noise suppression member 5 may also function as a damper that suppresses vibrations of the shaft 4.

[0054] In the above embodiment, the case in which the constant velocity universal joint according to the present invention is applied to a drive shaft was described, but the invention is not limited thereto. For example, the constant velocity universal joint according to the present invention may be applied to a propeller shaft.

[0055] In the above embodiment, the case in which the constant velocity universal joint according to the present invention is a sliding type constant velocity universal joint was described, but the constant velocity universal joint according to the present invention may also be a fixed type constant velocity universal joint. [Explanation of Symbols]

[0056] 1 drive shaft 2. Fixed constant velocity universal joint 3. Sliding constant velocity universal joint 4 Intermediate shaft 5. Electromagnetic noise suppression member 21 Outer joint member 22 Inner joint member 23 Ball 24 Cage 25 Boots 31 Outer joint member 32 Inner joint member 33 Roller Unit 34 Boots 41 Minimum diameter part 51 Magnetic material 52 Elastic body S1 Seal Space S2 Seal Space

Claims

1. A constant velocity universal joint comprising an outer joint member, an inner joint member disposed on the inner circumference of the outer joint member, a torque transmission member that transmits torque between the outer joint member and the inner joint member, a shaft with one end connected to the inner joint member, and a sealing device installed between the outer joint member and the shaft, A constant velocity universal joint characterized in that an electromagnetic noise suppression member containing a magnetic material is provided on the outer circumferential surface of the shaft within the sealed space enclosed by the outer joint member and the sealing device.

2. A constant velocity universal joint according to claim 1, provided on the inboard side of the drive shaft.

3. The constant velocity universal joint according to claim 1 or 2, wherein the outer diameter surface of the electromagnetic noise suppression member is an inclined surface that approaches the inner diameter side as it moves toward the other end of the shaft opposite to the one end.

4. The constant velocity universal joint according to claim 1 or 2, wherein the electromagnetic noise suppression member is provided on the outer circumferential surface of the shaft located within the seal space, at a position closer to the inner joint member.

5. The constant velocity universal joint according to claim 1 or 2, wherein the magnetic material is provided so as to surround the entire circumference of the outer surface of the shaft.

6. The constant velocity universal joint according to claim 1 or 2, wherein the electromagnetic noise suppression member is positioned by fitting with a recess or protrusion provided on the outer circumferential surface of the shaft.

7. The constant velocity universal joint according to claim 1 or 2, wherein the electromagnetic noise suppression member has an elastic body between the magnetic material and the outer surface of the shaft.

8. The shaft has a minimum diameter portion within the seal space where the shaft diameter is smallest, The constant velocity universal joint according to claim 1 or 2, wherein the electromagnetic noise suppression member is provided on the outer circumferential surface of the minimum diameter portion.

9. The constant velocity universal joint according to claim 1 or 2, wherein the magnetic material is a ferrite core.

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