Wheel drive system

Abstract

In a wheel drive system where the drive shaft is covered with a bellows-type boot, this invention provides a boot adapter that is easy to assemble and offers excellent durability and dust prevention for the boot. [Solution] The rotation of the drive shaft 1 is transmitted to the driven shaft which has an outboard cup 2, which is a universal joint member. The boot adapter 26 has a cylindrical portion 28, an inward projection 29 and an outward projection 30. The cylindrical portion 28 of the boot adapter 26 is held by the large diameter end 27a of the boot 27, and the large diameter end 27a and the cylindrical portion 28 are fixed to the outboard cup 2 by a band 32. The outward projection 30 of the boot adapter 26 is close to the bearing member 13, which prevents the detection surface of the rotation sensor 18 from being soiled with dust and prevents dust from entering the bearing 12.

Description

Technical Field

[0001] The present invention relates to a drive device that rotatably supports drive wheels of a vehicle (four-wheeled automobile) on a suspension device to transmit power.

Background Art

[0002] In four-wheeled automobiles, steered wheels are used as drive wheels to transmit power thereto. In this case, the drive wheels are supported by a suspension device so as to be capable of horizontal turning and rotatable, and power is transmitted to the drive wheels from a drive shaft via a universal joint. As the universal joint, an outboard cup with a built-in ball is widely used. Since the relative posture between the drive shaft and the outboard cup changes, the drive shaft is covered with a flexible boot having a bellows structure. Therefore, the boot is made of rubber-based synthetic resin.

[0003] Since the outboard cup has a larger diameter than the drive shaft, the boot has a bellows structure and a tapered shape whose outer diameter increases toward the outboard cup. The small-diameter end is often fixed to the drive shaft with a band, and the large-diameter end is often fixed to the outboard cup with a band. However, Patent Document 1 discloses that the large-diameter end of the boot is fixed to the outboard cup via a boot adapter.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Disclosure of the Invention

Problem to be Solved by the Invention

[0005] When attaching a boot directly to an outboard cup, the large-diameter portion of the boot must be forcibly pushed into the outboard cup while expanding it against its elasticity, making the installation process cumbersome. Patent Document 1 addresses this by using a boot adapter to facilitate the installation of the boot to the outboard cup, and is characterized by setting the large-diameter portion of the boot to a smaller diameter than the outer diameter of the outboard cup.

[0006] In other words, in Patent Document 1, the boot adapter is made of a metal plate and has a large-diameter cylindrical portion that holds the outboard cup. An inward-facing flange portion is integrally formed at one end of the large-diameter cylindrical portion, overlapping the end face of the outboard cup. Furthermore, a small-diameter cylindrical portion is integrally provided on the inward-facing flange portion, and the small-diameter cylindrical portion is held by the large-diameter portion of the boot. To prevent the boot from coming off, an inward-facing annular rib is formed on the large-diameter portion of the boot, and an annular groove is formed in the small-diameter cylindrical portion of the boot adapter into which the annular rib is forcibly fitted.

[0007] Upon consideration, while using a boot adapter as described in Patent Document 1 allows for easy attachment of the boot to the outboard cup, the large-diameter portion of the boot in Patent Document 1 is smaller in diameter compared to the direct-mount type. This results in a situation similar to using a downsized boot, leading to concerns about significantly reduced durability and decreased versatility due to a smaller maximum steering angle. Furthermore, since the boot has a dedicated structure, commercially available boots cannot be used, which is also a problem.

[0008] Furthermore, the large diameter portion of the boot is only fitted from the outside into the small diameter cylindrical portion of the boot adapter by its elastic force, and the external forces associated with steering act to pull the boot away from the small diameter cylindrical portion. As a result, the fit between the boot and the small diameter cylindrical portion loosens with continued use, and the boot becomes loose. There are concerns that the boot adapter may become loose. Furthermore, because the small diameter cylindrical portion of the boot adapter protrudes from the inward-facing flange, there are concerns that if small stones kicked up by the vehicle's movement hit the boot from below, the small diameter cylindrical portion may plastically deform, significantly reducing the boot's holding function.

[0009] Furthermore, the boot adapter described in Patent Document 1 is made of metal plate and appears to be manufactured by drawing a pipe material. However, achieving a high level of precision to ensure a snug fit with the outboard cup would require advanced technology, raising concerns about increased costs. Additionally, since it is made of metal plate, it would not be elastically deformable, making it difficult to securely hold it in place so that it does not detach from the outboard cup.

[0010] On the other hand, the outboard cup is rotatably held by a bearing member that rotates horizontally due to steering, and it is preferable to have a cover means to protect the gap between the outboard cup and the bearing member from entering. Conventionally, a dedicated cover was attached to the outboard cup, but this was costly because it was a dedicated product, and the installation work was also time-consuming.

[0011] The present invention was made against this backdrop, and while the method of attaching the boot to the outboard cup using a boot adapter is consistent with Patent Document 1, it aims to provide an improved form of the boot adapter. [Means for solving the problem]

[0012] The wheel drive device of the present invention is "It has a drive shaft driven by power from a power source, an outboard cup into which the tip of the drive shaft is inserted so as to transmit power from the drive shaft while allowing changes in the drive shaft's posture, and a flexible boot with a bellows structure that covers the drive shaft." The wheel is fixed to the outboard cup via a hub wheel, The boot has a tapered shape with one end having a small diameter and the other end having a large diameter, with one end fixed to the drive shaft and the other end fixed to the outboard cup via a boot adapter. This is the basic structure.

[0013] Furthermore, in the basic configuration described above, the present invention, "The boot adapter has a cylindrical portion that holds the outboard cup from the outside, and an inward projection provided at one end of the cylindrical portion so as to face the end face of the outboard cup, The other end of the boot is formed in a cylindrical shape and embraces the cylindrical portion of the boot adapter, or it is formed in an outward-facing flange and is pressed and fixed to one end face of the outboard cup by an inward-facing projection of the boot adapter. It possesses the following characteristics.

[0014] In the present invention, it is preferable to use a molded product made of synthetic resin for the boot adapter. To put it another way, there is no obstacle to making the boot adapter of the present invention a molded product made of synthetic resin (it is not impossible to make the boot adapter of Patent Document 1 out of synthetic resin, but the mold becomes complicated and manufacturing becomes troublesome).

[0015] The present invention can be developed in various ways. For example, in claim 2, "The outboard cup is rotatably held by a bearing member that is held in the suspension system so as to be able to change its horizontal orientation." The other end of the cylindrical portion constituting the boot adapter extends toward the bearing member, and the other end of the cylindrical portion of the boot adapter is provided with an outward-facing projection that is close to the bearing member. This is the configuration that is being adopted. [Effects of the Invention]

[0016] In the present invention, by adopting a configuration in which the large-diameter end of the boot is formed into a cylindrical shape to embrace the cylindrical portion of the boot adapter, commercially available boots can be used as is. However, since the cylindrical portion of the boot adapter is larger than the outer diameter of the outboard cup, a larger boot can be used compared to when the boot is directly attached to the outboard cup. Therefore, the durability of the boot can be improved, and the problem of reduced steering angle does not occur.

[0017] On the other hand, the embodiment in which the large-diameter end portion of the boot is formed as an inward flange and is pressed and held against the end face of the outboard cup can be adopted when the cylindrical portion of the boot adapter cannot be held by the large-diameter end portion of the boot due to relationships with other members. In this case, the boot can be set to the same size as the type that holds the outboard cup, so there is no need to reduce the size, and problems such as reduced durability and reduced steering angle do not occur.

[0018] Further, even if the boot is made of a rubber material, the inward flange has strong resistance to diameter reduction. Therefore, in the embodiment in which the inward flange of the boot is pressed and fixed to the end face of the outboard cup, the boot will not come off even if, for example, a small stone hits the boot, and high fixing strength can be secured. In the embodiment in which the cylindrical portion of the boot adapter is held by the cylindrical end portion, the boot can be firmly fixed with a band, so high fixing strength can also be secured in this case.

[0019] Furthermore, in any of the embodiments, since the boot adapter overlaps the outboard cup, it will not deform even when hit by small stones kicked up by the traveling of the vehicle, and the boot holding function will not be impaired.

[0020] In addition, when metal powder or small metal fragments are generated inside the outboard cup during continued use of the wheel drive device, in the conventional direct mounting method, the metal powder or metal fragments that fall from the edge of the outboard cup enter the gap between the hard outboard cup and the soft boot, and there is a concern that the boot may be damaged as the metal powder or metal fragments are rubbed between the boot and the outboard cup due to deformation of the boot. However, in the present invention, in any of the embodiments, the boot adapter has an inward portion facing the end face of the outboard cup, so the metal powder and metal fragments generated inside the outboard cup can be dropped onto the bellows portion of the boot, the metal powder and metal fragments are not rubbed between the hard outboard cup and the soft boot, and damage to the boot can be prevented.

[0021] Furthermore, since the boot adapter of the present invention can be easily manufactured from synthetic resin with high precision, not only can costs be suppressed, but also the boot can be securely attached to the outboard cup using elastic deformation in any boot mounting mode. Accordingly, the problem of dust entering through the gap between the boot adapter and the outboard cup never occurs, and the function of the boot can be ensured.

[0022] When the configuration of claim 2 is adopted, even if there is a gap between the bearing member and the outboard cup, the gap can be closed by the outward projection provided on the boot adapter. Accordingly, the bear It is possible to prevent problems such as dust entering the ring and the sensitivity of the rotation sensor provided on the bearing member being reduced by dust, and since a dedicated cover is not required, the manufacturing cost and mounting cost incurred when a dedicated component was used can be completely eliminated. [Brief Description of the Drawings]

[0023] [Figure 1] (A) is a plan cross-sectional view of the essential part of the first embodiment, and (B) is a partial plan cross-sectional view of the third embodiment. [Figure 2] (A) is an exploded plan cross-sectional view of the boot and the boot adapter, and (B) is a cross-sectional view taken along line B-B of (A). [Figure 3] This is a diagram showing the second embodiment, in which (A) is a plan cross-section of the essential part, (B) is a view of the boot adapter as seen from the B-B viewing direction of (A), and (C) is a view of the boot adapter as seen from the C-C viewing direction of (A). [Figure 4] It is a plan cross-sectional view showing the basic structure of the wheel drive device. [Figure 5] It is a plan cross-sectional view showing a conventional cover mounting procedure. [Mode for Carrying Out the Invention]

[0024] Next, embodiments of the present invention will be described in detail based on the drawings. In the following, the terms front, back, left, and right will be used to specify directions, but these directions are those viewed from the driver's perspective. Therefore, front and back refer to the forward and backward movement direction of the vehicle, and left and right refer to the width direction of the vehicle.

[0025] (1) Basic structure of wheel drive system First, let's explain the general outline of the wheel drive system with reference to Figure 4. Since the wheel drive system is applied to the steering wheels, it is basically a drive system for the front wheels. In other words, it refers to the drive system for the front wheels of a front-wheel drive vehicle or the front wheel drive system of a four-wheel drive vehicle.

[0026] In Figure 4 (and similarly in the other figures), power from a power source such as an engine or motor is transmitted to the drive shaft 1 via a differential gear (not shown). The rotation of the drive shaft 1 is transmitted to a driven shaft 3 having an outboard cup 2, and the rotation of the driven shaft 3 is transmitted to a hub wheel 4. The rim 5, which constitutes the front wheel, is fixed to the hub wheel 4 with stud bolts 6 and nuts 7.

[0027] The driven shaft 3 has a meshing portion 8 made of splines or serrations, and the hub wheel 4 is fixed to the driven shaft 3 by a nut 9 while meshed with the meshing portion 8. The hub wheel 4 has a flange 10, to which a brake disc 11 is fixed, and the rim 5 of the wheel (front wheel) is fixed by a nut 7 to the aforementioned stud bolt 6 provided on the flange 10.

[0028] The hub wheel 4 is rotatably held by the bearing member 13 via a ball bearing 12. The bearing member 13 is horizontally rotatably connected to a suspension system (not shown), and a knuckle 14 is fixed to it, to which the steering shaft of the steering system (front axle) is connected. The bearing member 13 rotates horizontally due to the pushing and pulling of the steering shaft, thereby changing the direction of the vehicle (steering).

[0029] The outboard cup 2 has a hollow structure into which the tip of the drive shaft 1 enters. Between the tip of the drive shaft 1 and the inner surface of the outboard cup 2, a group of balls 15 that constitute the interlocking member of the universal joint are arranged via a retainer 16.

[0030] The inner surface of the outboard cup 2 is formed in an arc shape, while an inner ring 17 with an arc cross-section, against which a group of balls 15 abuts, is held integrally with the tip of the drive shaft 1 so as to rotate. Even if the position of the outboard cup 2 changes, the balls 15 The group is kept in contact with the inner ring 17 and the outboard cup 2, and the power of the drive shaft 1 is transmitted to the outboard cup 2 (driven shaft 3) via the ball 15.

[0031] A rotation sensor 18 is attached to the bearing member 13 to detect the rotation of the outboard cup 2. Conventionally, a cover 19 was fixed to the outboard cup 2 to prevent dust from entering the gap between the outboard cup 2 and the bearing member 13. Therefore, the cover 19 is in close proximity to the bearing member 13 with only a small clearance. Reference numeral 20 indicates a cover that protects the brake disc.

[0032] A synthetic resin boot 21 surrounds the drive shaft 1 to prevent dust, pebbles, and other debris from entering the outboard cup 2. The boot 21 is tapered, having a small-diameter end (not shown) fixed to the drive shaft 1 and a large-diameter cylindrical portion 41 fixed to the outboard cup 2. Although schematically shown in Figure 4, in reality, the tapered portion has a bellows structure that is easily deformable to allow horizontal rotation of the outboard cup 2.

[0033] Generally, the cylindrical large-diameter end 22 of the boot 21 holds the outboard cup 2 from the outside and is secured to the outboard cup 2 by the band 23. In addition, the outboard cup 2 has an outward-facing annular groove 24 to prevent it from coming off, while the large-diameter end 22 of the boot 21 has an inward-facing annular projection that fits into the outward-facing annular groove 24.

[0034] (2) Structure of boot adapter and boot according to the first embodiment Figures 1(A) and 2 show examples of a boot adapter 26 embodying the present invention and a boot 27 fitted thereto. Specifically, Figures 1(A) and 2 show a first embodiment of the present invention. The boot adapter 26 of this embodiment has a circular cylindrical portion 28 that holds most of the outboard cup 2 from the outside, an inward-facing projection 29 connected to one end of the cylindrical portion 28 and facing the outer end surface of the outboard cup 2, and a flange-shaped (disc-shaped) outward-facing projection 30 located at the other end of the cylindrical portion 28 and close to the bearing member 13.

[0035] Furthermore, a portion of the cylindrical section 28 near one end is formed as a thin-walled section 28a. The boot adapter 26 is an injection-molded product made of synthetic resin, and is molded using a mold device that has a fixed mold and a movable mold that move relative to each other in the axial direction. A slide mold is used to mold the thin-walled section 28a.

[0036] The boot 27 has the same form as conventional boots, with a bellows structure that easily flexes and deforms, and a tapered deformation-allowing portion. The small-diameter end 34 is fixed to the drive shaft 1 by a band 35. The small-diameter end 34 has an outward-facing annular groove 36 for preventing the band 35 from slipping, and an inward-facing annular projection 38 that fits into an annular groove 37 provided on the outer circumference of the drive shaft 1.

[0037] The large-diameter end 27a of the boot 27 is formed in a cylindrical portion that embraces about half of the cylindrical portion 28 of the boot adapter 26. An outward-facing annular groove 27b into which the band 32 fits is formed on the outer surface of the large-diameter end 27a, and an inward-facing annular projection 31 is formed on the inner circumferential surface of the large-diameter end 27a, facing the outward-facing annular groove 24 of the outboard cup 2 via the thin-walled portion 28a of the cylindrical portion 28 of the boot adapter 26. When the large-diameter end 27a of the boot 27 is secured with the band 32, the thin-walled portion 28a of the boot adapter 26 is pressed and bent by the inward-facing annular projection 31 of the boot 27 and fits into the outward-facing annular groove 24 of the outboard cup 2. As a result, the large-diameter end 27a of the boot 27 and the cylindrical portion 28a of the boot adapter 26 are fixed to the outboard cup 2 in a non-slip state.

[0038] (3) Summary of the first embodiment The boot adapter 26 is pre-set on the boot 27, and the boot 27 is installed by fitting the boot adapter 26 into the outboard cup 2 and securing it with the band 25. Therefore, installation to the outboard cup 2 can be easily performed.

[0039] In this embodiment, existing commercially available boots 27 can be used as is, but in that case, a size larger can be used. Therefore, the stress due to deformation can be reduced and durability can be greatly improved. In addition, since commercially available products can be used as is, costs can also be kept down.

[0040] As the vehicle continues to be used, it is expected that metal powder and metal fragments will be generated inside the outboard cup 2. In this case, the metal powder and metal fragments will fall downward from the opening edge of the outboard cup 2 as indicated by the arrows in Figure 1(A) (Figure 1(A) is a plan view cross-section, but the shape will be the same when viewed as a longitudinal section). However, since the inward projection 29 of the boot adapter 26 overlaps the end face of the outboard cup 2, the metal powder and metal fragments will be guided past the inward projection 29 to the bellows section of the boot 27.

[0041] Therefore, the phenomenon of metal powder or metal fragments rubbing against the hard outboard cup 2 and the soft boot 27 does not occur, and damage to the boot 27 can be prevented. In this case, as in the embodiment, it is preferable to widen the inner circumferential surface of the inward projection 29 outwards, as this enhances the guiding effect of the metal powder or metal fragments.

[0042] As explained with reference to Figure 4, conventionally, a cover 19 was fixed to the outboard cup 2 to prevent dust from entering between the outboard cup 2 and the bearing member 13, but the cover 19 needs to be precisely positioned and fixed. On the other hand, as shown in Figure 5, the drive shaft 1 and the driven shaft 3 are integrally connected to form a universal joint unit, and when assembling the vehicle, the procedure is to first connect the universal joint unit to the differential box, then fit the bearing member 13 onto the driven shaft 3, then fit and fix the hub wheel 4 onto the driven shaft 3, and fix the bearing member 13 to the suspension device.

[0043] Therefore, the cover 19 had to be fixed in a predetermined position on the outboard cup 2 before the assembly into the bearing member 13 and the fixing of the hub wheel 4. Thus, as shown by the dashed line in Figure 5, the cover 19 was positioned using a jig 40 that contacts the other end face 2b of the outboard cup 2, and the cover 19 was fixed in that position. As a result, the installation of the cover 19 was very time-consuming.

[0044] In contrast, in this embodiment, the outward projection 30 provided on the cylindrical portion 28 of the boot adapter functions as a cover, eliminating the need for the conventional cover 19, and thus reducing the effort required for vehicle assembly. Furthermore, since the outboard cup 2 is manufactured to precise dimensions, and the thickness of the flange 39 of the boot 27 is also manufactured to precise dimensions, when the boot 27 is fixed to the outboard cup 2 with the inward projection 29 pressing against the end face of the flange 39 of the outboard cup 2, the outward projection 30 is pivotally positioned with a predetermined gap between it and the bearing member 13.

[0045] (4) Other embodiments Figure 3 shows a second embodiment. In this second embodiment, the inward projection 29 of the boot adapter 26 abuts against one end face 2a of the outboard cup 2. The cylindrical portion 28 is set to a large diameter, and the cylindrical portion 28 is held by the large diameter cylindrical portion 41 of the boot 27, and the large diameter cylindrical portion 41 and the cylindrical portion 28 are fixed to the outboard cup 2 by a band 25. Although shown in a simplified form, part 27 has a bellows structure similar to that in Figure 1.

[0046] An outward-facing annular groove 42 is formed in the cylindrical portion 28 of the boot adapter 26 to prevent the boot 27 from shifting, and an inward-facing annular projection 43 is formed in the large-diameter cylindrical portion 41 of the boot 27 to fit into the outward-facing annular groove 42. Furthermore, in this embodiment, since the wall thickness of the cylindrical portion 28 is large, as a means to equalize the wall thickness to the minimum necessary, first, a number of outward-facing material removal grooves 44 are formed intermittently in the circumferential direction on the side where the inward-facing projection 29 is provided.

[0047] On the side of the cylindrical portion 28 that is not fitted to the outboard cup 2, the wall is thinned and the diameter is increased, and a large number of inward-facing ribs 45 are formed, so that the group of inward-facing ribs 45 abuts against the outer surface of the outboard cup 2. In other words, the diameter of the cylindrical portion 28 is increased by raising it with the group of inward-facing ribs 45. It is also possible to increase the diameter while making the wall thickness uniform by forming a large number of material-removing grooves that are radially inward and open on the other end side.

[0048] In any case, the other end face 28b of the cylindrical portion 28 is in close proximity to the side surface of the bearing member 13 with only a very small clearance, and therefore, in this embodiment, the cylindrical portion 28 functions as a cover. It is also possible to provide a flange-shaped outward projection at the other end of the cylindrical portion 28, or to provide an enclosure frame portion 46 shown by the dashed line in Figure 3(A).

[0049] In this embodiment as well, it is possible to use a commercially available boot 27 that is one size larger than the standard size, but it is also possible to use an even larger size than in the first embodiment. This reduces the stress caused by deformation and further improves durability.

[0050] Figure 1(B) shows a third embodiment. In this embodiment, one end of the cylindrical portion 28 of the boot adapter 26 is formed as a thin-walled portion 28a, and an inward-facing annular projection 31 is formed on the thin-walled portion 28a, which acts as a stopper that fits into the outward-facing annular groove 24 of the outboard cup 2. By arranging the inward-facing projection 29 and the inward-facing annular projection 31 so as not to overlap when viewed from the axial direction, the molding process is facilitated.

[0051] Multiple inward-facing annular projections 31 are formed in a circumferential direction (for example, at four locations), and consequently, the inward-facing projections 29 are also divided into multiple sections. The cylindrical portion 28 is fixed to the outboard cup 2 by a band 32 at the thin-walled portion 28a.

[0052] The large-diameter end of the boot 27 is formed with an outward-facing flange 39, which is held in place by an inward-facing projection 29 of the boot adapter 26 against one end face 2a of the outboard cup 2. Therefore, the outward-facing flange 39 of the boot 27 is fitted into the boot adapter 26 after the large-diameter portion of the boot 27 is narrowed and deformed.

[0053] In this embodiment, the outward flange 39 of the boot 27 is surrounded by the cylindrical portion 28 of the boot adapter 26, so it cannot be set to a diameter larger than the outer diameter of the outboard cup 2, but the maximum diameter of the bellows portion can be set arbitrarily. In the figured configuration, the maximum diameter of the bellows portion is set to be approximately the same as the outer diameter of the outboard cup 2, but it is possible to form it to a diameter larger than the outer diameter of the outboard cup 2, and at the very least, it can be set to the same size as conventional products that are adapted to the size of the outboard cup 2. Therefore, the boot 27 can be easily deformed to ensure high durability.

[0054] For the boot 27 attached to the outboard cup 2 to detach due to external force, the flange 39 must be narrowed and deformed. However, it is difficult to narrow the outward-facing flange 39, which is held in place by the inward-facing projection 29 of the outboard cup 2. Therefore, the outward-facing flange 39 may become more prone to detachment due to wear and tear during use. Furthermore, there is absolutely no phenomenon of pebbles kicked up by the vehicle's movement hitting the bellows section and causing the flange 39 to detach, and the fixed state can be firmly maintained.

[0055] Furthermore, in Patent Document 1, the small-diameter cylindrical portion of the boot adapter 26 protrudes from the outboard cup, and the large-diameter end of the boot is fixed to this protruding small-diameter cylindrical portion, resulting in a shorter boot length. Consequently, the load acting per unit area due to boot deformation increases. However, in this embodiment, the outward-facing flange 39 is pressed and fixed to the end face of the outboard cup 2, so the length of the bellows portion of the boot 27 is not shortened, and therefore, the stress on the bellows portion does not increase. High durability can be ensured in this respect as well.

[0056] Although embodiments of the present invention have been described above, the present invention can be implemented in various other ways. [Industrial applicability]

[0057] The present invention can be implemented in a wheel drive system. Therefore, it can be used industrially. [Explanation of Symbols]

[0058] 1 drive shaft 2 Outboard Cups 3 Driven axis 4 hub wheels 5 Wheel rims 12 bearings 13 Bearing member 14 Knuckle 15 Balls constituting the interlocking members of a universal joint 16 Retainers 17 Inner Ring 18 Rotation Sensor 19 Conventional cover structure 21 Traditional boots 24 Outward-facing annular groove 26 Boot Adapters 27 Boots 27a Tubular large-diameter end of boot 28 Cylinder 29 Inward-facing projection 30 Outward-facing protrusions 31 Stopper protrusion 34 Small diameter end of boot 39 Outward flange forming the large diameter end of the boot

Claims

1. It comprises a drive shaft driven by power from a power source, an outboard cup into which the tip of the drive shaft is inserted so as to transmit power from the drive shaft while allowing changes in the drive shaft's orientation, and a flexible boot with a bellows structure that covers the drive shaft. The wheel is fixed to the outboard cup via a hub wheel, The aforementioned boot has a tapered shape with one end having a small diameter and the other end having a large diameter, and is a wheel drive device in which one end is fixed to the drive shaft and the other end is fixed to the outboard cup via a boot adapter, The boot adapter has a cylindrical portion that holds the outboard cup from the outside, and an inward projection provided at one end of the cylindrical portion so as to face the end face of the outboard cup. The other end of the boot is formed in a cylindrical shape and embraces the cylindrical portion of the boot adapter, or it is formed in an outward-facing flange and is pressed and fixed to one end face of the outboard cup by an inward-facing projection of the boot adapter. Wheel drive system.

2. The outboard cup is rotatably held by a bearing member that is held in the suspension system so as to be able to change its horizontal orientation. The other end of the cylindrical portion constituting the boot adapter extends toward the bearing member, and the other end of the cylindrical portion of the boot adapter is provided with an outward-facing projection that is close to the bearing member. A wheel drive device as described in claim 1.

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