JP2002178708A - Wheel driving bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a structure for preventing an entrance of foreign matters into a line engaging part of a spline hole 15 and a spline shaft 17b. SOLUTION: A cap 32 is fitted to and installed in an outer end part of a hub 4b to block up the outer end side of the spline engaging part. A seal ring 39 is fitted around a base end part of the spline shaft 17b to block up the inner end side of the spline engaging part. The cap 32 is made of an inexpensive synthetic resin to attain the purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel drive bearing unit in which a constant velocity joint and a wheel support bearing unit are integrated, and a drive wheel ｛FF vehicle (front type) supported by an independent suspension type suspension. Engine with front-wheel drive)
Of the front wheels, rear wheels of FR vehicles (rear-wheel drive vehicle with front engine) and RR vehicles (rear-wheel drive vehicle of rear engine), and all wheels of 4WD vehicle (four-wheel drive vehicle) can be freely rotated with respect to the suspension system. And used to rotationally drive the drive wheels. That is, in order to support the driving wheels on the independent suspension type and to rotate the driving wheels, a wheel supporting bearing unit, and a differential constant velocity joint and a wheel constant velocity joint at both ends of the driving shaft, respectively. A drive unit for a wheel is used in combination with a constant velocity joint unit to which the above-mentioned is coupled. The wheel drive bearing unit to which the present invention is applied is a combination of a wheel support bearing unit and a wheel side constant velocity joint which constitute such a wheel drive unit.

[0002]

2. Description of the Related Art In order to rotatably support wheels with respect to a suspension device, various bearing units are used in which an outer ring and an inner ring are rotatably combined via rolling elements. or,
In addition to supporting the drive wheels on an independent suspension,
The wheel drive bearing unit for rotating this drive wheel, in combination with a constant velocity joint, controls the rotation of the drive shaft regardless of the relative displacement between the differential gear and the drive wheel and the steering angle given to the wheel. It must be transmitted smoothly (with constant velocity) to the wheels. Conventionally, various wheel drive bearing units combining a wheel support bearing unit and a constant velocity joint have been used for such a purpose. In addition, various structures have been proposed to reduce the weight and cost of the wheel drive bearing unit by connecting the wheel support bearing unit and the constant velocity joint without using a nut. I have.

FIG. 13 shows a first example of a conventional structure described in US Pat. No. 4,881,842. This wheel drive bearing unit is formed by connecting a wheel support bearing unit 1 and a constant velocity joint 2. The wheel supporting bearing unit 1 includes a hub 4 and an inner ring 5 rotatably supported on the inner diameter side of the outer ring 3 via a plurality of rolling elements 6. The outer race 3 does not rotate during use in a state where the outer race 3 is connected and fixed to a knuckle 8 constituting a suspension system by an outward flange-shaped mounting portion 7 provided on the outer peripheral surface thereof.
It is to be noted that a structure in which the outer peripheral surface of the outer ring 3 is a simple cylindrical surface (without forming the mounting portion 7) and the outer ring 3 is internally fitted and fixed in a support hole of the knuckle 8 is also conventionally known. On the inner peripheral surface of the outer ring 3, double-row outer ring tracks 9, 9 are provided.
The hub 4 and the inner ring 5 are rotatably supported concentrically with the outer ring 3 on the inner diameter side of the outer ring 3.

[0004] Of these, the hub 4 is located near the outer periphery (in the axial direction, outside in the width direction of the vehicle when assembled to the vehicle; the same throughout the present specification; the left side in each drawing). A flange 10 for supporting a wheel is provided.
Further, an inner raceway 11a corresponding to the first inner raceway described in the claims is formed at an intermediate portion of the outer peripheral surface of the hub 4, and the inner raceway 11a is also formed inside (in the axial direction, the width of the vehicle when assembled to the automobile). The center in the direction. Same throughout the specification. The right side of each drawing.) A small-diameter portion 12 formed near the end, an outer peripheral surface thereof, and another inner race corresponding to the second inner race described in the claims. The inner ring 5 formed with 11b is externally fitted and fixed. A retaining ring 14 is retained in a retaining groove 13 formed all around the outer peripheral surface of a portion of the inner end of the hub 4 protruding inward in the axial direction from the inner end surface of the inner ring 5. The retaining ring 14 suppresses the inner end surface of the inner ring 5 to prevent the inner ring 5 from shifting in the axial direction. A spline hole 15 is provided in the center of the hub 4.

On the other hand, the constant velocity joint 2 includes a drive shaft member 16. The drive shaft member 16 has a spline shaft 17 which can be engaged with the spline hole 15 in the outer half.
And an outer ring 18 for a constant velocity joint in the inner half. Outer engagement grooves 19 are formed at a plurality of circumferential positions on the inner circumferential surface of the outer race 18 for constant velocity joints, respectively, in a direction perpendicular to the circumferential direction. On the inner diameter side of such an outer ring 18 for a constant velocity joint, an inner engaging groove is formed in a part of the outer peripheral surface which is aligned with the outer engaging groove 19 in a direction perpendicular to the circumferential direction. , A constant velocity joint inner ring is provided. Then, a ball (not shown) is held between the inner engagement groove and the outer engagement groove 19 by a retainer (not shown), and freely rolls along the inner and outer engagement grooves. Provided. The shape and the like of each component of the constant velocity joint 2 are the same as those of the well-known Zeppa type or Barfield type constant velocity joint, and are not related to the gist of the present invention. Description is omitted.

[0006] The constant velocity joint 2 as described above and the wheel supporting bearing unit 1 as described above are connected to the spline shaft 17.
Into the spline hole 15 of the hub 4 from the inside to the outside in the axial direction. And the spline shaft 17
A locking groove 20 which is an inner diameter side engaging portion formed at a portion near the front end of the outer peripheral surface, and an outer diameter side engaging portion provided at a portion of the inner peripheral surface of the hub 4 facing the locking groove 20. The spline shaft 17 is prevented from coming out of the hub 4 by bridging the retaining ring 22 with the locking step portion 21 which is a portion. In this state, the hub 4 and the drive shaft member 16 are
The elastic ring 23 is elastically compressed between the outer ring 18 for a constant velocity joint and the hub 4 and the drive shaft member 16 to prevent axial displacement.

Further, when assembled to the suspension system of the automobile, a male spline, which is also provided in the outer half of the drive shaft (not shown), is provided in a second spline hole provided in the center of the inner ring for the constant velocity joint (not shown). The drive shaft and the inner race for a constant velocity joint are coupled to each other so as to be able to transmit a rotational force by engaging the portions with a spline. Also, the inner end of this drive shaft
It is connected to the output part of a tripod type constant velocity joint, which is another constant velocity joint provided on the differential side. The tripod-type constant velocity joint, the drive shaft, and the constant velocity joint 2 constitute a constant velocity joint unit. Before assembly to the car,
The constant velocity joint unit and the wheel supporting bearing unit 1 are combined to constitute the above-described wheel drive unit.

The first structure of the conventional structure shown in FIG.
In the case of the example, the spline hole 15 and the spline shaft 1 are used.
No consideration is given to preventing foreign matter such as rainwater from entering the spline engagement portion with the spline 7. On the other hand, Japanese Patent Application Laid-Open No. 2000-142009 describes a structure for preventing rust on the spline engagement portion by preventing foreign matter from entering the spline engagement portion. FIG.
Shows a second example of the conventional structure described in the above publication.

In the case of the second example of the conventional structure shown in FIG. 14, the inner ring raceway 11b is formed on the outer peripheral surface of the step portion 24 formed at the inner end of the main body of the hub 4a constituting the wheel supporting bearing unit 1a. The formed inner ring 5 is externally fitted. At the same time, the inner ring 5 is fixed to the main body portion by a caulking portion 25 formed by plastically deforming a portion protruding from the inner end surface of the inner ring 5 at the inner end of the main body portion in the diametrically outward direction. ing. A cap 26 formed by plastically deforming a metal plate is fitted and fixed to the outer end opening of the hub 4a.
This outer end opening is closed, and a spline hole 1 is inserted from the outer end side.
5 and a drive shaft member 16a constituting the constant velocity joint 2a
This prevents foreign matter such as rainwater from entering the spline engagement portion with the spline shaft 17a provided on the outer half of the spline shaft.
Further, an inner locking groove 27 is formed on the outer peripheral surface near the outer end of the spline shaft 17a over the entire circumference. An outer locking groove 28 is formed over the entire circumference at a position matching the inner locking groove 27 on the inner peripheral surface of the intermediate portion near the outer end of the spline hole 15. In addition, in both the inner and outer locking grooves 27 and 28, a partially annular retaining ring 29 is mounted so as to extend over the both locking grooves 27 and 28.

An X-shaped cross-section is provided between the portion between the spline shaft 17a and the outer race 18a for the constant velocity joint on the outer peripheral surface of the intermediate portion of the drive shaft member 16a and the inner peripheral surface of the inner end portion of the hub 4a. A seal ring 30 is provided. The seal ring 30 made of an elastic material such as an elastomer such as rubber, and the cap 26 together with the spline shaft 17a and the spline engagement portion between the spline hole 15 are almost completely sealed. This prevents foreign matter such as rainwater containing dust from entering the engagement portion, and prevents the spline engagement portion from rusting or promoting the wear of the engagement portion.

[0011]

In the case of the conventional structure as shown in FIG. 14 described above, a metal cap 26, which is a relatively expensive component, is used while foreign substances can be prevented from entering the spline engagement portion. For this reason, the cost increases. In view of such circumstances, the present invention has been made to realize a wheel drive bearing unit that can be manufactured at low cost without using expensive components and that can prevent foreign matter from entering a spline engagement portion. is there.

[0012]

A wheel drive bearing unit according to the present invention comprises an outer ring, a hub, a plurality of rolling elements, and a drive unit, similarly to the above-described conventionally known wheel drive bearing unit. A shaft member, a seal member, and a cap are provided. Of these, the outer ring has a double-row outer ring track on the inner peripheral surface, and does not rotate during use. Further, the hub has a flange for supporting the wheel at a portion near the outer end of the outer peripheral surface, a first inner raceway directly or at an intermediate portion of the outer peripheral surface via a separate inner ring, and a spline hole at the center. In addition to providing each,
An inner race having a second inner raceway formed on the outer peripheral surface is externally fitted and fixed to a portion near the inner end of the outer peripheral surface. In addition, each of the rolling elements is disposed between the outer raceway and the first and second inner raceways.
A plurality of each are provided so as to freely roll. or,
In the drive shaft member, a spline shaft that engages with the spline hole is provided in an outer half portion, and an inner half portion is an outer race for a constant velocity joint that forms a constant velocity joint. The seal member is provided between the hub and the drive shaft member at a portion closer to the inner end than the spline engagement portion between the spline hole and the spline shaft, and the inner end side of the spline engagement portion is provided. Seal. Further, the cap is attached to an outer end opening of the hub, and seals an outer end side of the spline engagement portion. In particular, in the wheel drive bearing unit of the present invention, the cap is made of a synthetic resin having no mandrel.

[0013]

According to the present invention constructed as described above, a cap made of a synthetic resin, which is inexpensive compared to a metal cap, is used to prevent foreign matter from entering the spline engagement portion. Thus, a wheel drive bearing unit capable of achieving sufficient durability can be realized at low cost.

[0014]

1 and 2 show a first embodiment of the present invention. The feature of the present invention is that spline engagement between the hub 4b constituting the wheel supporting bearing unit 1b and the spline shaft 17b of the drive shaft member 16b constituting the constant velocity joint 2b is performed without using expensive parts. This is to prevent foreign matter from entering the part. Since the configuration and operation of the other parts are the same as those of the second example of the conventional structure shown in FIG. 14, the same parts are denoted by the same reference numerals and redundant description is omitted or simplified. The following description focuses on the features of the present invention and the portions different from the above-described conventional structure.

In the case of this embodiment, the cylindrical portion 3 formed to fit the inner peripheral edge of the wheel to the outer end surface of the hub 4b.
1 is fitted with a cap 32 made of synthetic resin to prevent foreign matter from entering the spline engagement portion from the outer end side. The cap 32 continues the base end of the short cylindrical fitting cylinder 34 from the outer peripheral edge of the circular closing plate 33, and furthermore, the distal end of the fitting cylinder 34 has an outward flange-like positioning. A flange 35 is provided. Such a cap 3
2, the fitting cylinder 34 is fitted inside the cylinder 31 by interference fit, and the positioning flange 35 is connected to the cylinder 3
1 is abutted against the leading edge to achieve positioning in the axial direction.

In the case of this example, the cap 32 as described above is
Polyphenylene sulfide (PPS) as the main component,
In order to reinforce this and to reduce the difference in the coefficient of thermal expansion from the hub 4b, 50% by weight of glass fiber is contained. The reason is as follows. The temperatures of the hub 4b and the cap 32 greatly change due to changes in the ambient temperature due to seasonal changes and the like, and heat generated due to friction between the pad and the rotor during braking. Therefore, the hub 4
If there is a large difference between the coefficient of thermal expansion of the material forming b and the coefficient of thermal expansion of the material forming the cap 32,
The interference of the fitting cylindrical portion 34 with respect to the cylindrical portion 31 greatly changes.

PP containing no reinforcing material such as glass fiber
The linear expansion coefficient of S alone is about 7 × 10 ⁻⁵ cm / cm / ° C.,
The coefficient of linear expansion of the steel constituting the hub 4b (1.1 × 10
^-5 cm / cm / ° C). Therefore, when the cap 32 is made only of PPS, the interference is small at a low temperature, and the cap 32 is easily dropped from the cylindrical portion 31. Conversely, when the temperature is high, the interference is excessive, and the cap 32 is cracked or plastically deformed. For this reason, the interference is reduced with a decrease in temperature, and the cap 32 is also easily dropped from the cylindrical portion 31. When considering safety, the temperature is-
Within the range of 40 to + 150 ° C., it is preferable that the above-mentioned interference is within an appropriate range.

In the case of the present embodiment, the difference between the linear expansion coefficient of the cap 32 and the linear expansion coefficient of the hub 4b is substantially reduced by including 50% by weight of glass fibers in the PPS constituting the cap 32. Lost. Therefore, regardless of the ambient temperature change, the cap 32 is attached to the cylindrical portion 31.
Can be sufficiently prevented from falling off. When the glass fiber is contained in the PPS at 50% by weight, the difference between the linear expansion coefficient of the cap 32 and the linear expansion coefficient of the hub 4b can be almost eliminated as described above. However, if the amount of glass fibers contained in the PPS is 30% by weight, the linear expansion coefficient is 1.8 ×
Since the linear expansion coefficient of the steel constituting the hub 4b is 10 ⁻⁵ cm / cm / ° C., the change in the interference can be suppressed to a practically acceptable level. In particular, when the content of the glass fiber is set to 40% by weight or more, the change in the interference can be sufficiently suppressed even under a severe use condition in terms of temperature. It should be noted that increasing the content of the glass fiber beyond 50% by weight is almost meaningless from the viewpoint of suppressing a change in interference. If the content of glass fiber becomes too large,
The proportion of PPS is reduced, and the strength of the cap 32 is rather reduced. In consideration of this point, the content of the glass fiber is suppressed at most to 60% by weight or less.

On the other hand, on the inner peripheral surface of the inner end of the hub 4b,
A conical concave guide inclined surface portion 36 which is continuous from the inner end portion of the spline hole 15 and is inclined in a direction in which the inner diameter increases as the distance from the spline hole 15 increases, and continuous from the large diameter side end portion of the guide inclined surface portion 36 Cylindrical surface part 37
Are formed by turning or the like. Of these, the guide inclined surface portion 36 is formed in the inner locking groove 2 formed at the tip end thereof.
When the spline shaft 17b, in which the retaining ring 29 is previously locked to the spline shaft 7, is pushed into the spline hole 15, the retaining ring 29
Are provided to elastically reduce the diameter of the retaining ring 29 based on engagement with the outer peripheral edge of the retaining ring. The cylindrical surface portion 37 is
In order to form a caulking portion 25a provided at the inner end of the hub 4b, the preformed portion is formed at the inner end of the hub 4b. Is not what you need. Strictly speaking, the shape of the cylindrical surface portion 37 is a tapered surface that is inclined such that the inner diameter increases toward the inner end side.

An inner end of a spline shaft 17b constituting an outer half of the drive shaft member 16b,
A cylindrical portion 38 slightly larger in diameter than the spline shaft 17b is provided between the inner ring 6b and the outer end of the outer race 18b for a constant velocity joint. And this cylindrical part 3
A seal ring 39 is elastically held between the outer peripheral surface of the inner surface 8 and the inner peripheral surface of the cylindrical surface 37. The seal ring 39 is made of an elastomer such as rubber without a mandrel in order to reduce the cost, and is formed in an annular shape entirely with an elastomer such as rubber. The seal lip 40 is inclined inwardly toward the outside in the radial direction. In such a seal ring 39, the base portion 41 is fitted over the cylindrical portion 38 by interference fit, and the distal end edge (outer peripheral edge) of the seal lip 40 is elastically attached to the cylindrical surface portion 37 over the entire circumference. Contact.

Such a seal ring 39 is connected to the hub 4.
Prior to inserting the spline shaft 17b of the drive shaft member 16b into the spline hole 15 provided at the center of b, the spline shaft 17b is externally fitted to the cylindrical portion 38. This external fitting work,
This is performed using a cylindrical sleeve 42 as shown in FIG. That is, the sleeve 42 on which the seal ring 39 has been fitted in advance is covered (loosely fitted) on the spline shaft 17b, and the leading edge (right edge in FIG. 2) of the sleeve 42 is brought close to the cylindrical portion 38. And this sleeve 42
The seal ring 39 is pushed into the cylindrical portion 38 by a cylindrical press-fitting jig 43 placed on the cylindrical portion 38. Therefore, the inner peripheral surface of the seal ring 39 does not come into contact with the spline teeth having the edge and is not damaged by the mounting operation.

As described above, the base 4 of the seal ring 39
When the first member 1 is fitted to the cylindrical portion 38 by interference fit, the spline shaft 17b is inserted into the spline hole 15 of the hub 4b from the inner end opening side of the spline hole 15.
A retaining ring 29 for preventing separation between the hub 4b and the drive shaft member 16b is mounted on an inner locking groove 27 formed on the outer peripheral surface of the tip of the spline shaft 17b prior to the insertion operation. Keep it. In this state, the spline shaft 17
When the b is pushed into the spline hole 15, the diameter of the retaining ring 29 is reduced by the engagement between the outer peripheral edge of the retaining ring 29 and the guide inclined surface portion 36.
The spline shaft 17b is pushed into the spline hole 15.

When the inner locking groove 27 and the outer locking groove 28 formed near the outer end of the inner peripheral surface of the spline hole 15 are aligned with each other, the diameter of the retaining ring 29 is elastically increased. The retaining ring 29 spreads, and is bridged between the inner engaging groove 27 and the outer engaging groove 28. As a result, separation between the hub 4b and the drive shaft member 16b is prevented. In this state, the seal ring 39 enters the inner diameter side of the caulking portion 25a provided at the inner end of the hub 4b, and the leading edge of the seal lip 40 is
7 is elastically contacted over the entire circumference. As described above, since the seal lip 40 is inclined inward toward the outside in the radial direction, the seal lip 40 enters the inside diameter side of the cylindrical surface portion 37 without being turned.
As described above, since the seal lip is deformed by a light load, the force required to push the seal ring 39 into the inner diameter side of the cylindrical surface portion 37 is smaller than that of a structure having no seal lip such as an O-ring. Even without using a machine such as a robot, it is possible to perform the pushing work sufficiently,
In addition, after being pushed, sufficient sealing performance can be obtained.

Since the seal ring 39 is only fitted on the cylindrical portion 38, there is a possibility that the seal ring 39 is displaced in the axial direction due to vibration applied during use. Even in this case, before the base portion 41 separates from the cylindrical portion 38, the base portion 41 is fixed to the cylindrical portion so that the axial outer edge of the outer peripheral surface of the seal ring 39 abuts on the guide inclined surface portion 36. 38.

Next, FIGS. 3 to 5 show a second example of the embodiment of the present invention. In the case of this example, the cap 32a
Is made of polyamide 66 containing 40% by weight of glass fiber. Polyamide 66 alone has a coefficient of linear expansion of 8
× a 10 ^-5 cm / cm / ℃ about, but it is much larger than the linear expansion coefficient of the steel constituting the hub ^{4b (1.1 × 10 -5 cm /} cm / ℃), if the PPS Similarly to the above, by mixing glass fibers, the coefficient of linear expansion can be reduced to approach the value of steel. For example, the coefficient of linear expansion of polyamide 66 mixed with 30% by weight or more of glass fiber is 2.5 × 10 ^−5.
cm / cm / ° C or less. This value is higher than the value of PPS mixed with 30% by weight of glass fiber, but in the case of polyamide 66, the Young's modulus is lower than that of PPS (easily elastically deformed).
Therefore, it can be used with a larger interference than in the case of PPS. Therefore, in the case of this example, the cap 3
Polyamide 6 containing 40% by weight of glass fiber mixed with 2a
6 and a cylindrical portion 3 provided at the inner end of the hub 4b.
First, the fitting is made with a larger interference than in the case of the first example.

However, it is difficult to make the interference extremely large. Therefore, in the case of this example, the cap 32a and the cylindrical portion 31 are engaged with each other in a concave and convex manner, thereby improving the performance of preventing the cap 32a from falling off from the cylindrical portion 31. For this reason, in the case of the present example, the locking groove 44 is formed on the inner peripheral surface of the cylindrical portion 31 over the entire circumference, and the leading edge of the fitting cylindrical portion 34a constituting the cap 32a (see FIG. Locking claw pieces 45, 45 are formed at a plurality of locations (2 to 6 locations) in the circumferential direction (right edge in FIGS. 3 to 5). The fitting cylindrical portion 34a extends over the entire circumference to a portion of the inner surface of the disc-shaped closing plate portion 33a that is slightly radially inward from the outer peripheral edge of the closing plate portion 33a. Has formed. The outer diameter of the fitting cylindrical portion 34a in the free state is slightly larger than the inner diameter of the cylindrical portion 31. Therefore, the fitting cylindrical portion 34a can be fitted inside the cylindrical portion 31 by interference fit.

The locking claw pieces 45, 45 are formed at a plurality of positions at the tip end of the fitting tube portion 34a at equal intervals so as to protrude inward in the axial direction. ,
A hook 46 that can be engaged with the locking groove 44 is formed.
Further, each of the locking claw pieces 4 is formed at the leading edge of the fitting cylindrical portion 34a.
Cuts 47, 47 are formed at positions sandwiching the base end portions of the locking claw pieces 4, 45 from both sides in the circumferential direction.
5, 45 are easily elastically deformed. Accordingly, there is no occurrence of damage such as cracking at the base end of each of the locking claw pieces 45, 45 as the hook 46 is pushed into the locking groove 44. If the cuts 47 are deepened,
The axial position of the leading edge of each of the locking claw pieces 45, 45 and the axial position of the leading edge of the fitting tubular portion 34a can be made to coincide with each other.

The cap 32a as described above is attached to the cylindrical portion 3
The fitting cylindrical portion 34a is fitted into the cylindrical portion 31 with an interference fit in the opening 1 and the outer diameter side end of the closing plate portion 33a is abutted against the leading edge of the cylindrical portion 31. hand,
Axial positioning is attempted. Also, in this state, the hook portions 46 of the locking claw pieces 45, 45 engage with the locking grooves 44, thereby preventing the fitting cylindrical portion 34a from coming out of the cylindrical portion 31. The engagement allowance ₄₆ (FIG. 4) between the hook portion 46 and the locking groove 44 is sufficiently large, and the engagement allowance ₄₆ is lost due to the difference in the amount of thermal expansion between the cap 32a and the hub 4b. Nothing. Therefore, the cap 32a does not fall off the hub 4b regardless of the temperature change.

In the case of the present embodiment, a seal ring is formed on a step portion 48 formed at a middle portion of the drive shaft member 16b at a continuous portion between an outer end portion of the spline shaft 17b and an inner end portion of the constant velocity joint outer ring 18b. 39a is fitted outside. Then, the seal ring 39a is provided on the outer end surface of the outer race 18b for a constant velocity joint and the caulking portion 25 formed on the inner end of the hub 4b.
a is elastically sandwiched between the inner end surface of a. As in the case of the above-described first example, this seal ring 39a is also made of an elastomer such as rubber, and is made entirely of an annular shape without cost for cost reduction. The seal lip 40a is provided on the outer surface. The seal lip 40a is inclined in the outward direction as it goes radially outward. The distal end edge of such a seal lip 40a is elastically brought into contact with the inner end surface of the caulked portion 25a over the entire circumference. In order to stabilize the contact state of this portion, the inner end surface of the caulked portion 25a is processed into a flat surface. The configuration and operation of the other parts are the same as those described in the first embodiment.
Since this is the same as in the case of the example, the same parts are denoted by the same reference numerals, and duplicate description will be omitted.

FIG. 6 shows a third embodiment of the present invention.
An example is shown. In the case of this example, the cap 32b is
It is made of polyamide 46 containing 50% by weight of glass fibers. Polyamide 46 alone has a coefficient of linear expansion of 8 × 1
0 ^-5 cm / cm / is about ° C., but it is much larger than the linear expansion coefficient of the steel constituting the hub ^{4b (1.1 × 10 -5 cm /} cm / ℃), in the case of PPS Similarly, by incorporating glass fibers, the coefficient of linear expansion can be reduced to approach that of steel. For example, the coefficient of linear expansion of polyamide 46 containing 30% by weight of glass fiber is 2.4 × 10 ⁻⁵ cm / cm / ° C.
It is as follows. This value is higher than the value of PPS mixed with 30% by weight of glass fiber.
Since the tensile strength is higher and the Young's modulus is lower (easily elastically deformed) than PS, it can be used with a larger interference than in the case of PPS. Therefore, in the case of this example, the cap 32b is fitted to the cylindrical portion 31 provided at the inner end of the hub 4b with a larger interference than in the case of the first example.

The cap 32b is provided with a fitting cylindrical portion 34b on the inner surface of a disc-shaped closing plate portion 33b.
b is formed over the entire circumference at a portion slightly inward in the radial direction from the outer peripheral edge. The outer diameter of the fitting cylindrical portion 34b in the free state is slightly larger than the inner diameter of the cylindrical portion 31 formed at the outer end of the hub 4b. Therefore, the fitting cylindrical portion 34b can be fitted into the cylindrical portion 31 by tight fitting.
In the case of this example, a locking groove 49 is formed on the outer peripheral surface of the fitting cylindrical portion 34b over the entire circumference, and the outer peripheral edge of the O-ring 50 held in the locking groove 49 is formed. The inner peripheral surface of the cylindrical portion 31 is elastically abutted over the entire circumference. Such an O-ring 50 improves the sealing performance on the outer end side of the hub 4b, and also serves to prevent the cap 32b from coming off the cylindrical portion 31.

Further, in the case of the present embodiment, a step portion 48 is formed in a middle portion of the drive shaft member 16b at a continuous portion between an outer end portion of the spline shaft 17b and an inner end portion of the constant velocity joint outer ring 18b.
As the seal ring 39b which is fitted to the outside, a base ring 41b reinforced with a core metal 51 is used. By using such a seal ring 39b with a cored bar, the fitting strength between the base portion 41b and the step portion 48 is increased, and the seal ring 39b is used during the assembly operation of the wheel drive bearing unit. Dropping from the part 48 can be reliably prevented. Since the configuration and operation of the other parts are the same as those of the above-described second example, the same reference numerals are given to the same parts, and the duplicate description will be omitted.

Next, FIGS. 7 and 8 show a fourth embodiment of the present invention. In the case of this example, the cap 32c
Is made of polyamide 66 alone, which does not contain glass fibers or the like. As described above, since the linear expansion coefficient of the polyamide 66 is considerably larger than the linear expansion coefficient of the steel constituting the hub 4b, the cap 32c is provided at the outer end of the hub 4b regardless of the temperature change. In order to prevent the cap 32c from coming off the part 31, the interference between the cap 32c and the cylindrical part 31 must be sufficiently large. On the other hand, even if this interference is increased, in order to prevent damage such as cracks from occurring in the polyamide 66 constituting the cap 32c, even if the cap 32c is fitted inside the cylindrical portion 31, It is necessary to keep the stress generated in each part of the cap 32c low.

In consideration of such points, in the case of the present embodiment, the central portion of the closing plate portion 33c has a partially spherical shape so that the closing plate portion 33c is easily elastically deformed in the radial direction.
In addition, the entire cap 32c has a thickness of 1.0 mm or less so as to be easily deformed, so that even when the cap 32c is internally fitted to the cylindrical portion 31 with a large interference fit, the stress applied to each portion can be kept low. I have.

Further, in the illustrated example, a groove 52 having a depth △ ₅₂ of about 0.2 to 0.5 mm is formed on a portion of the inner peripheral surface of the intermediate portion of the cylindrical portion 31 facing the outer peripheral edge of the closing plate portion 33c. Is formed over the entire circumference. And the cap 32c
In the outer peripheral surface of the inner end portion of the fitting cylindrical portion 34c, a ridge 53 is formed over the entire periphery at a portion corresponding to the outer peripheral edge of the closing plate portion 33c. The tip green (outer peripheral edge) of the ridge 53 is in contact with the bottom of the concave groove 52 over the entire circumference. With this configuration, while improving the sealing performance of the fitting portion between the cylindrical portion 31 and the cap 32c,
The cap 32c is prevented from accidentally falling off the cylindrical portion 31. Other configurations and operations are the same as those of the above-described third example. Therefore, the same parts are denoted by the same reference numerals, and overlapping description will be omitted.

Next, FIG. 9 shows a fifth embodiment of the present invention.
An example is shown. In the case of the present example, the outer peripheral edge of the circular plate-shaped closing plate portion 33d constituting the cap 32d and the short cylindrical fitting cylindrical portion 34d are connected to each other by an annular connecting portion 54 having an L-shaped cross section. Is continuous. With such a configuration, the fitting cylindrical portion 34d is easily elastically deformed, and the fitting cylindrical portion 34d is provided at the outer end of the hub 4b.
In contrast to (see FIG. 7), the stress generated in each part of the cap 32d can be suppressed to a low level even if the cap 32d is internally fitted with a large interference. In the case of the present example, the fitting cylinder 34
The protruding ridge 53 formed on the outer peripheral surface of the inner end of d is located axially inward of the closing plate 33d. Other configurations and operations are the same as those of the above-described fourth example, and therefore, duplicated illustration and description will be omitted.

Next, FIG. 10 shows a sixth embodiment of the present invention. In the case of this example, the entire cap 32e is pushed into the cylindrical portion 31 formed at the outer end of the hub 4b. In other words, the leading edge of the fitting cylinder 34e provided on the outer peripheral edge of the cap 32e is
While exposing the outer end edge 55 of the cylindrical portion 31 so as not to project radially outward from the outer end edge 55 of the
It protrudes most outward in the axial direction. The outer edge 55 can be used as a reference surface for checking whirling of the tire at the time of tire replacement or the like.

When disassembling the wheel supporting bearing unit 1b and the constant velocity joint 2b, it is necessary to remove the cap 32e from the inside of the cylindrical portion 31. In the case of (1), a knob 56 is provided at the center of the outer surface of the closing plate 33e. When removing the cap 32e from the inside of the cylindrical portion 31, the knob 56 is gripped with a tool such as a plier, and the cap 32e is removed from the inside of the cylindrical portion 31. In the present embodiment, only one knob 56 is formed at the center. However, it is also possible to form knobs at a plurality of circumferentially equally spaced locations offset from the center position in the radial direction.
By adopting such a configuration and pulling a plurality of knobs simultaneously, it becomes possible to remove the cap from the cylindrical portion 31 without inclining the cap. Other configurations and operations are the same as those of the fifth example described above, and therefore, the same parts are denoted by the same reference numerals and overlapping description will be omitted.

Next, FIGS. 11 to 12 show a seventh embodiment of the present invention. Also in the case of this example, the sixth
As in the case of the example, the cylindrical portion 3 provided at the outer end of the hub 4b
The first outer edge 55 is exposed without being covered by the cap 32f. For this reason, in the case of this example, the axial dimension of the fitting cylindrical portion 34f formed on the outer peripheral edge of the disc-shaped closing plate portion 33f constituting the cap 32f is reduced. Instead, the outer peripheral edge of the inner surface of the cap 32f is formed on the inner peripheral surface of the intermediate portion of the cylindrical portion 31 by a step 57
The cap 32f is made to contact the entire circumference to prevent the cap 32f from tilting.

Further, when disassembling the wheel supporting bearing unit 1b and the constant velocity joint 2b, as a clue for pulling out the cap 32f from the cylindrical portion 31, a plurality of points (at the leading edge of the fitting cylindrical portion 34f) are provided. For example, three places)
The locking projections 58 are formed to protrude. Each of the locking projections 58, 58 has a hook 5
By forming 9, a drawing jig (not shown) can be locked freely. Therefore, the operation of extracting the cap 32f from the cylindrical portion 31 can be easily performed. When the above-described cap 32f is injection-molded by an axial draw in order to reduce the cost, first, the outer mold in the radial direction is separated in the axial direction, and the above-described hook, which has just been molded in the cavity, is used. It is necessary to axially separate the radially inner mold while elastically deforming the locking projections 58, 58 including the portion 59 radially outward. In the case of the example shown,
By making each of the locking projections 58, 58 protrude in the axial direction from the distal end edge of the fitting cylindrical portion 34f, it is easy to be elastically deformed in the radial direction. The locking projections 58 are hardly damaged, and the cap 32
The yield of f can be sufficiently secured.

[0041]

Since the present invention is constructed and operates as described above, it is possible to realize a low-cost wheel driving bearing unit having excellent durability by suppressing rusting and abrasion of the spline engaging portion. This can contribute to improving the performance of the vehicle and reducing the cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a state in which a ceiling is mounted on an intermediate portion of a drive shaft member.

FIG. 3 is a sectional view showing a second example of the embodiment of the present invention.

FIG. 4 is an enlarged view of a portion A in FIG. 3;

FIG. 5 is a view showing only the cap taken out and viewed from above in FIG. 4;

FIG. 6 is a sectional view showing a third example of the embodiment of the present invention.

FIG. 7 is a sectional view showing the fourth example.

FIG. 8 is an enlarged view of a portion B in FIG. 7;

FIG. 9 is a sectional view showing a fifth example of the embodiment of the present invention by extracting only a cap.

FIG. 10 is a sectional view showing a sixth example.

FIG. 11 is a sectional view showing a seventh example.

FIG. 12 is a perspective view showing only a cap taken out.

FIG. 13 is a sectional view showing a first example of a conventional structure.

FIG. 14 is a sectional view showing the second example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 1a, 1b Wheel support bearing unit 2, 2a, 2b Constant velocity joint 3 Outer ring 4, 4a, 4b Hub 5 Inner ring 6 Rolling element 7 Mounting part 8 Knuckle 9 Outer ring raceway 10 Flange 11a, 11b Inner ring raceway 12 Small diameter part 13 Locking groove 14 Retaining ring 15 Spline hole 16, 16a, 16b Drive shaft member 17, 17a, 17b Spline shaft 18, 18a, 18b Outer ring for constant velocity joint 19 Outer engaging groove 20 Locking groove 21 Locking step 22 Stop Ring 23 elastic ring 24 stepped portion 25, 25a caulking portion 26 cap 27 inner locking groove 28 outer locking groove 29 retaining ring 30 seal ring 31 cylindrical portion 32, 32a, 32b, 32c, 32d, 32e, 32
f cap 33, 33a, 33b, 33c, 33d, 33e, 33
f Closing plate portions 34, 34a, 34b, 34c, 34d, 34e, 34
f Fitting cylindrical portion 35 Positioning flange portion 36 Guide inclined surface portion 37 Cylindrical surface portion 38 Cylindrical portion 39, 39a, 39b Seal ring 40, 40a Seal lip 41, 41a, 41b Base 42 Sleeve 43 Press-in jig 44 Lock groove 45 Lock Claw piece 46 Hook 47 Notch 48 Step 49 Locking groove 500 Ring 50 Core bar 52 Concave groove 53 Protrusion 54 Connecting part 55 Outer edge 56 Knob 57 Step 58 Locking protrusion 59 Hook

Claims (1)

[Claims] 1. A first inner ring raceway having a double row of outer raceways on an inner peripheral surface and not rotating even during use, and a flange for supporting wheels at a portion near the outer end of the outer peripheral surface. Alternatively, a spline hole is provided at the center portion of the outer peripheral surface through a separate inner ring, and a spline hole is provided at the center, and an inner ring having a second inner ring track formed on the outer peripheral surface is externally fitted and fixed to a portion near the inner end of the outer peripheral surface. A plurality of rolling elements respectively provided between the outer raceways and the first and second inner raceways so as to freely roll, and a spline shaft which is spline-engaged with the spline hole. A drive shaft member which is provided in a half part and has an inner half part as an outer race for a constant velocity joint which constitutes a constant velocity joint, and a hub which is closer to an inner end than a spline engagement portion between the spline hole and the spline shaft. And a drive shaft member. A wheel drive bearing unit including a seal member that seals an inner end side of a spline engagement portion, and a cap that is attached to an outer end opening of the hub and seals an outer end side of the spline engagement portion. In this case, the cap is made of a synthetic resin having no mandrel, and is a bearing unit for driving a wheel.