JP6901241B2 - Constant velocity universal joint - Google Patents

Description

The present invention relates to a constant velocity universal joint used in a power transmission system of an automobile or various industrial machines, and particularly to be incorporated in a drive shaft or a propeller shaft for an automobile.

There are two types of constant velocity universal joints used as means for transmitting rotational force from an automobile engine to wheels at a constant velocity: a fixed constant velocity universal joint and a sliding constant velocity universal joint. Both of these constant-velocity universal joints have a structure in which two shafts on the driving side and the driven side are connected and the rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle.

The drive shaft that transmits power from the engine to the wheels needs to correspond to angular displacement and axial displacement due to changes in the relative positional relationship between the engine and the wheels. Therefore, the drive shaft is generally equipped with a sliding constant velocity universal joint on the engine side (inboard side) and a fixed constant velocity universal joint on the wheel side (outboard side). It has a structure in which universal joints are connected by a shaft.

The fixed constant velocity universal joint described above includes an outer joint member, an inner joint member, a plurality of balls and a cage. The end of the shaft extending from the sliding constant velocity universal joint is connected to the shaft hole of the inner joint member of the fixed constant velocity universal joint so that torque can be transmitted by spline fitting.

Conventionally, various types of connecting structures for connecting the inner joint member of the fixed constant velocity universal joint and the shaft in this drive shaft have been proposed (see, for example, Patent Document 1).

In the connection structure of Patent Document 1 (see FIG. 1), as shown in FIG. 9, a male spline 128 is formed on the outer peripheral surface of the end portion of the shaft 120, and a male spline 128 is formed on the inner peripheral surface of the shaft hole 127 of the inner joint member 112. The female spline 129 is formed, the end of the shaft 120 is inserted into the shaft hole 127 of the inner joint member 112, and the male spline 128 and the female spline 129 are joined by uneven fitting.

An annular groove 130 is formed at the end of the shaft 120, and a stepped portion 131 is formed on the inner peripheral surface of the shaft hole 127 of the inner joint member 112. The step portion 131 is open to the end surface of the inner joint member 112.

By fitting the retaining ring 132 into the annular groove 130 of the shaft 120 and locking the retaining ring 132 to the stepped portion 131 of the inner joint member 112, the shaft 120 is prevented from coming off from the inner joint member 112. There is.

On the other hand, as shown in FIG. 10, the male spline 128 formed on the outer peripheral surface of the shaft 120 has a rounded shape in which the small diameter portion (tooth bottom portion) 133 is smoothly expanded and connected to the outer peripheral surface. A shoulder portion 136 having an outer diameter d _{2 larger than the outer diameter d 1} of the large diameter portion (tooth tip portion) 135 of the male spline 128 is formed at a portion slightly distant from the rounded end portion 134 of the male spline 128. (D ₁ <d ₂ ).

By bringing the end face portion 141 of the inner joint member 112 into contact with the shoulder portion 136 of the shaft 120, the inner joint member 112 is restrained in the axial direction so as not to move to the side opposite to the end portion of the shaft 120. Here, the end face portion 141 is a tapered portion from the end face of the inner joint member 112 to the stealing portion 137.

As described above, by locking the retaining ring 132 of the annular groove 130 of the shaft 120 to the stepped portion 131 of the inner joint member 112, the shaft 120 is prevented from coming off from the inner joint member 112, and the shaft 120 is prevented from coming off. The shaft 120 and the inner joint member 112 are assembled by abutting the end surface portion 141 of the inner joint member 112 on the shoulder portion 136 and restraining the inner joint member 112 in the axial direction.

Japanese Patent No. 4271301

By the way, in the above-described connection structure between the inner joint member 112 and the shaft 120, the end surface portion 141 of the inner joint member 112 is provided on the shoulder portion 136 located at a portion slightly distant from the rounded end portion 134 of the male spline 128 of the shaft 120. Since the inner joint member 112 is constrained in the axial direction by being brought into contact with each other, it has the following problems.

Here, in a constant velocity universal joint, boots are generally mounted between the outer joint member and the shaft 120 in order to prevent lubricant leakage from the inside of the joint and foreign matter from entering from the outside of the joint. Therefore, as shown in FIG. 9, the small-diameter end portion of the boot is tightened and fixed to the protrusion 125 of the shaft 120 by the boot band.

The boot is assembled to the shaft 120 by passing the shoulder portion 136 of the shaft 120 through the small diameter end portion of the boot and then fixing the small diameter end portion to the protrusion 125. Therefore, the protrusion 125 has an outer diameter d _{3 larger than the outer diameter d 2} of the shoulder 136 (d ₃ > d ₂ ), and the outer diameter d ₃ of the protrusion 125 is the maximum diameter of the shaft 120. ..

In the production of the shaft 120, a material having an outer diameter including a cutting allowance for forming the protrusion 125 which is the maximum diameter of the shaft 120 is required. For this reason, the material diameter of the shaft 120 is restricted, it is difficult to reduce the material diameter, and it is difficult to reduce the cost.

Therefore, the present invention has been proposed in view of the above-mentioned improvements, and an object of the present invention is to provide a constant velocity universal joint capable of reducing the material diameter of the shaft with a simple structure and reducing the cost. There is.

The constant velocity universal joint according to the present invention includes an outer joint member and an inner joint member that transmits rotational torque while allowing angular displacement via a torque transmission member between the outer joint member, and the inner joint thereof. It has a structure in which a shaft member is inserted into a shaft hole of the member, and the inner joint member and the shaft member are connected by spline fitting so that torque can be transmitted.

As a technical means for achieving the above-mentioned object, the present invention has a male spline formed on the outer peripheral surface of a shaft member in a cut-out shape, and a shoulder portion having an outer diameter smaller than the large diameter portion of the male spline. It is characterized in that the small diameter end portion of the female spline formed on the outer peripheral surface of the shaft member and formed on the inner peripheral surface of the shaft hole of the inner joint member is brought into contact with the shoulder portion of the shaft member.

In the present invention, the male spline of the shaft member has a cut-out shape, and the small diameter end of the female spline of the inner joint member is brought into contact with the shoulder of the shaft member, so that the outer diameter of the shoulder of the shaft member can be adjusted. It can be made smaller than before. In this way, by reducing the outer diameter of the shoulder portion passed through the small diameter end of the boot, the outer diameter of the protrusion that fixes the small diameter end of the boot, that is, the maximum diameter of the shaft member is made smaller than before. can do.

In the present invention, it is desirable that a stealing portion is formed on the female spline of the inner joint member, and the small diameter end portion of the female spline located at the stealing portion is brought into contact with the shoulder portion of the shaft member.

If such a structure is adopted, the small diameter end of the female spline located at the stealing portion is brought into contact with the shoulder of the shaft member, so that the outer diameter of the shoulder passed through the small diameter end of the boot is further increased. It is effective in that it can be made smaller.

In the present invention, the small-diameter end of the female spline of the inner joint member and the shoulder of the shaft member form a tapered shape, and the small-diameter end of the female spline is brought into contact with the shoulder of the shaft member at the same taper angle. Is desirable.

If such a structure is adopted, the small diameter end of the female spline is brought into contact with the shoulder of the shaft member at the same taper angle, so that the axial position of the shoulder of the shaft member can be accurately secured. ..

In the present invention, it is desirable that the cut-out end of the male spline of the shaft member has a tapered shape, and the taper angle of the cut-out end is smaller than the taper angle of the shoulder.

By adopting such a structure, even if the male spline has a cut-out shape whose torsional strength is lower than that of the cut-up shape, the taper angle of the cut-out end is made smaller than the taper angle of the shoulder, so that the male spline can be used. It is possible to relax the stress concentration at the cut-out end of the.

According to the present invention, the male spline of the shaft member has a cut-out shape, and the small diameter end of the female spline of the inner joint member is brought into contact with the shoulder of the shaft member, so that the boot can pass through the small diameter end of the boot. The outer diameter of the shoulder portion of the shaft member to be formed can be made smaller than before. As a result, the outer diameter of the protrusion that fixes the small diameter end of the boot, that is, the maximum diameter of the shaft member can be made smaller than before. As a result, the material diameter of the shaft can be reduced, so that the cost of the constant velocity universal joint can be reduced.

It is sectional drawing which shows the connection structure of the inner joint member and a shaft in embodiment of this invention. It is an enlarged cross-sectional view which shows the part A of FIG. It is sectional drawing which shows the connection structure of the inner joint member and a shaft in another embodiment of this invention. It is an enlarged cross-sectional view which shows the part B of FIG. It is sectional drawing which shows the connection structure of the inner joint member and a shaft in the reference example of this invention. It is an enlarged cross-sectional view which shows the part C of FIG. It is a block diagram which shows the procedure of turning the annular groove of the shaft of FIG. 1 and a shoulder portion at the same time. It is sectional drawing which shows the whole structure of the constant velocity universal joint. It is sectional drawing which shows the conventional connection structure of an inner joint member and a shaft. It is an enlarged cross-sectional view which shows the part D of FIG.

An embodiment of a constant velocity universal joint according to the present invention will be described in detail below with reference to the drawings.

In the following embodiment, a zipper type constant velocity universal joint (BJ), which is one of the fixed constant velocity universal joints incorporated in an automobile drive shaft, is illustrated, but undercut-free as another fixed constant velocity universal joint. It can also be applied to type constant velocity universal joints (UJ). It is also applicable to sliding type constant velocity universal joints such as double offset type constant velocity universal joints (DOJ), cross groove type constant velocity universal joints (LJ) and tripod type constant velocity universal joints (TJ).

Drive shafts incorporated in automobiles such as 4WD vehicles and FR vehicles need to cope with angular displacement and axial displacement due to changes in the relative positional relationship between the engine and wheels. Therefore, the drive shaft is generally equipped with a sliding constant velocity universal joint on the engine side (inboard side) and a fixed constant velocity universal joint on the wheel side (outboard side). It has a structure in which universal joints are connected by a shaft.

As shown in FIG. 8, the fixed constant velocity universal joint (hereinafter, simply referred to as a constant velocity universal joint) of this embodiment is a cup-shaped outer joint member 11, an inner joint member 12, and a torque transmission member. A main part is composed of a plurality of balls 13 and a cage 14.

In the outer joint member 11, arcuate track grooves 15 extending in the axial direction are formed at a plurality of locations on the spherical inner peripheral surface 16 in the circumferential direction at equal intervals. In the inner joint member 12, arcuate track grooves 17 extending in the axial direction in pairs with the track grooves 15 of the outer joint member 11 are formed at a plurality of locations on the spherical outer peripheral surface 18 in the circumferential direction at equal intervals.

The ball 13 is interposed between the track groove 15 of the outer joint member 11 and the track groove 17 of the inner joint member 12 to transmit rotational torque. The cage 14 is arranged between the inner peripheral surface 16 of the outer joint member 11 and the outer peripheral surface 18 of the inner joint member 12 to hold the ball 13. The number of balls 13 may be 6, 8, or other, and the number thereof is arbitrary.

In the constant velocity universal joint having the above configuration, when an operating angle (angle displacement of the shaft 20 with respect to the outer joint member 11) is given, the ball 13 held by the cage 14 always has the operating angle at any operating angle. It is maintained within the bisector of the joint, and the constant velocity of the joint is ensured.

In this constant velocity universal joint, by enclosing a lubricant such as grease in the internal space of the outer joint member 11, the inner joint is formed with respect to the sliding portion inside the joint, that is, the outer joint member 11 when the joint is operated. The lubricity of the sliding portion of the internal component including the member 12, the ball 13 and the cage 14 is ensured.

This constant velocity universal joint has an opening 19 of the outer joint member 11 and a shaft member extending from the inner joint member 12 in order to prevent leakage of the lubricant sealed inside the joint and prevent foreign matter from entering from the outside of the joint. A structure in which a resin or rubber bellows-shaped boot 21 is mounted between the shaft 20 and the shaft 20 is provided.

The large-diameter end 22 of the boot 21 is fastened and fixed to the outer peripheral surface of the opening 19 of the outer joint member 11 by the boot band 23, and the small-diameter end 24 of the boot 21 is a protrusion formed on the outer peripheral surface of the shaft 20. It is tightened and fixed to 25 by a boot band 26.

On the other hand, one end of the shaft 20 is connected to the shaft hole 27 of the inner joint member 12 by spline fitting so that torque can be transmitted. As shown in FIG. 1, the connecting structure of the inner joint member 12 and the shaft 20 forms a male spline 28 on the outer peripheral surface of the end portion of the shaft 20 and is formed on the inner peripheral surface of the shaft hole 27 of the inner joint member 12. A female spline 29 is formed, an end portion of the shaft 20 is inserted into the shaft hole 27 of the inner joint member 12, and the male spline 28 and the female spline 29 are joined by uneven fitting.

An annular groove 30 is formed at the end of the shaft 20, and a step portion 31 is formed on the inner peripheral surface of the shaft hole 27 of the inner joint member 12. The step portion 31 is open to the end surface of the inner joint member 12. By fitting the retaining ring 32 into the annular groove 30 of the shaft 20 and locking the retaining ring 32 to the stepped portion 31 of the inner joint member 12, the shaft 20 is prevented from coming off from the inner joint member 12. There is.

On the other hand, as shown in FIG. 2, the male spline 28 formed on the outer peripheral surface of the shaft 20 has a cut-out shape in which the small diameter portion (tooth bottom portion) 33 is directly cut out on the outer peripheral surface of the shaft 20. A shoulder portion 36 having an outer diameter D _{2 smaller than the outer diameter D 1} of the large diameter portion (tooth tip portion) 35 of the male spline 28 is formed at a portion slightly distant from the cut-out end portion 34 of the male spline 28. Yes (D ₁ > D ₂ ).

As shown in FIG. 2, a stealing portion 37 is formed on a female spline 29 extending in the axial direction from the end face portion 41 of the inner joint member 12. The small-diameter end 38 of the female spline 29 located at the stealing portion 37 of the inner joint member 12 is brought into contact with the shoulder portion 36 of the shaft 20. As a result, the inner joint member 12 is restrained in the axial direction so as not to move to the side opposite to the end portion of the shaft 20. Here, the above-mentioned end face portion 41 is a tapered portion from the end face of the inner joint member 12 to the stealing portion 37.

As described above, by locking the retaining ring 32 of the annular groove 30 of the shaft 20 to the stepped portion 31 of the inner joint member 12, the shaft 20 is prevented from coming off from the inner joint member 12 and the shaft 20 is prevented from coming off. The shaft 20 and the inner joint member 12 are assembled by abutting the small diameter end 38 of the female spline 29 of the inner joint member 12 on the shoulder portion 36 to restrain the inner joint member 12 in the axial direction. ..

In the constant velocity universal joint of this embodiment, the male spline 28 of the shaft 20 has a cut-out shape, and the small diameter end 38 of the female spline 29 of the inner joint member 12 is brought into contact with the shoulder portion 36 of the shaft 20. _{As a result, the outer diameter D 2} of the shoulder portion 36 of the shaft 20 can be made smaller than _{the outer diameter d 2} of the shoulder portion 136 of the conventional shaft 120 (see FIGS. 9 and 10) _{(D 2} <d _2). ).

That is, in the conventional constant velocity universal joint (see FIG. 10), the outer diameter d ₂ of the shoulder portion 136 of the shaft 120 was larger than _{the outer diameter d 1} of the male spline 128 _{(d 2} > d ₁ ). In the constant velocity universal joint of this embodiment (see FIG. 2), the outer diameter D ₂ of the shoulder portion 36 of the shaft 20 can be made smaller than _{the outer diameter D 1} (= d ₁ ) of the male spline 28 (D). ₂ <D ₁ ).

_{As a result, the outer diameter D 2} of the shoulder portion 36 of the shaft 20 (see FIGS. 1 and 2) in this embodiment is changed from _{the outer diameter d 2} of the shoulder portion 136 of the conventional shaft 120 (see FIGS. 9 and 10). Can also be reduced (D ₂ <d ₂ ).

_{In this way, by reducing the outer diameter D 2} of the shoulder portion 36 passed through the small diameter end portion 24 (see FIG. 8) of the boot 21, the small diameter end portion 24 of the boot 21 is tightened and fixed by the boot band 26. The outer diameter D ₃ of the protrusion 25 (see FIG. 1), that is, the maximum diameter of the shaft 20 is made smaller than _{the outer diameter d 3} of the protrusion 125 of the shaft 120 in the conventional constant velocity universal joint (see FIG. 9). Can be done (D ₃ <d ₃ ).

As a result, with respect to the material of the shaft 20 having an outer diameter including a cutting allowance for forming the protrusion 25 which is the maximum diameter of the shaft 20, the material diameter of the shaft 20 is not restricted and the material diameter is reduced. Therefore, the cost of the constant velocity universal joint can be reduced.

Further, in the connecting structure between the inner joint member 12 and the shaft 20, the contact surface between the small diameter end 38 of the female spline 29 of the inner joint member 12 and the shoulder portion 36 of the shaft 20 has a tapered shape. The small diameter end 38 of the female spline 29 is brought into contact with the shoulder 36 of the shaft 20 at the same taper angle α. That is, the taper angle α of the small diameter end 38 of the female spline 29 and the taper angle α of the shoulder 36 of the shaft 20 are made the same.

By adopting such a structure, the small diameter end 38 of the female spline 29 is brought into contact with the shoulder 36 of the shaft 20 at the same taper angle α, so that the axial position of the shoulder 36 of the shaft 20 is accurate. Can be secured well.

As shown in FIG. 7, the annular groove 30 and the shoulder portion 36 of the shaft 20 are machined by simultaneously turning on the slide stage 51 with the tips 54 and 55 supported by the holders 52 and 53. By this simultaneous turning process, it is possible to accurately secure the axial position of the shoulder portion 36 of the shaft 20, that is, the separation dimension between the annular groove 30 and the shoulder portion 36.

Here, in the conventional constant velocity universal joint (see FIG. 10), the male spline 128 of the shaft 120 has a rounded shape, whereas in the constant velocity universal joint (see FIG. 2) of this embodiment, the shaft The 20 male splines 28 have a cut-out shape. In the case of the cut-out male spline 28, the torsional strength tends to be lower than that of the cut-out male spline 128, so that the structures shown in FIGS. 3 and 4 are effective.

In the constant velocity universal joint of the embodiment shown in FIGS. 3 and 4, in the connecting structure of the inner joint member 12 and the shaft 20, the cut-out end portion 39 of the male spline 28 of the shaft 20 has a tapered shape, and the cut-out end portion 39 thereof has a tapered shape. The structure is such that the taper angle β of 39 is smaller than the taper angle α of the shoulder portion 36 (β <α).

By adopting such a structure, even if the male spline 28 has a cut-out shape in which the torsional strength is lower than the cut-up shape, the taper angle β of the cut-out end portion 39 is smaller than the taper angle α of the shoulder portion 36. By doing so, the stress concentration at the cut-out end 39 of the male spline 28 can be relaxed.

That is, at the cut-out end portion 39 of the male spline 28, the height of the large-diameter portion (tooth tip portion) 35 of the male spline 28 gradually decreases and the axial dimension becomes longer, so that the cut-out end portion 39 of the male spline 28 acts. The load to be distributed is distributed. Therefore, the stress concentration at the cut-out end 39 of the male spline 28 can be relaxed. By relaxing this stress concentration, it is possible to suppress a decrease in torsional strength.

In the above embodiment, a stealing portion 37 is formed on the female spline 29 of the inner joint member 12, and the small diameter end portion 38 of the female spline 29 located at the stealing portion 37 is brought into contact with the shoulder portion 36 of the shaft 20. However, as in the embodiment shown in FIGS. 3 and 4, the structure shown in FIGS. 5 and 6 may be used by increasing the axial dimension of the cut-out end portion 39 of the male spline 28.

In the constant velocity universal joints shown in FIGS. 5 and 6 as reference examples, the stealing portion 37 (see FIGS. 3 and 4) is not formed on the female spline 29 of the inner contact member 12. In the connecting structure between the inner joint member 12 and the shaft 20, the small diameter end 40 of the female spline 29 extending axially from the end face 41 of the inner joint member 12 is brought into contact with the shoulder 36 of the shaft 20.

Here, since the female spline 29 does not have the stealing portion 37, when the fitting start position between the female spline 29 of the inner joint member 12 and the male spline 28 of the shaft 20 approaches the end face side of the inner joint member 12, the inner joint member The strength of 12 may decrease.

However, as in the reference example shown in FIGS. 5 and 6, by lengthening the axial dimension of the cut-out end 39 of the male spline 28, the inner joint is formed even if the female spline 29 does not have the stealing portion 37. Since the fitting start position of the female spline 29 of the member 12 and the male spline 28 of the shaft 20 is the same as in the case of the embodiment shown in FIGS. 3 and 4, the strength of the inner joint member 12 can be ensured. ..

The present invention is not limited to the above-described embodiments, and it goes without saying that the present invention can be carried out in various forms without departing from the gist of the present invention. Indicated by the scope of the claim and further includes the equal meaning described in the claims, and all modifications within the scope.

11 Outer joint member 12 Inner joint member 13 Torque transmission member (ball)
20 Shaft member (shaft)
27 Shaft hole 28 Male spline 29 Female spline 36 Shoulder 37 Steal part 38 Small diameter end 39 Cut-out end

Claims (3)

An inner joint member that transmits rotational torque while allowing angular displacement between the outer joint member and the outer joint member via a torque transmission member is provided, and the shaft member is inserted into the shaft hole of the inner joint member. , A constant velocity universal joint in which the inner joint member and the shaft member are coupled so that torque can be transmitted by spline fitting.
A male spline formed on the outer peripheral surface of the shaft member is formed into a cut-out shape, and a shoulder portion having an outer diameter smaller than the large diameter portion of the male spline is formed on the outer peripheral surface of the shaft member.
Said female spline formed on the inner peripheral surface of the shaft hole of the inner joint member, to the female spline is formed on an end portion of the insertion direction opposite to the time of inserting the shaft member in the axial hole of the inner joint member In addition, a stealing portion having a tooth tip diameter larger than the tooth tip diameter of another part of the female spline and a tapered small-diameter end formed on the insertion direction side of the stealing portion are provided.
A constant-velocity universal joint characterized in that a small-diameter end portion of a female spline formed on the insertion direction side of the stealing portion is brought into contact with the shoulder portion of a shaft member. The small-diameter end of the female spline of the inner joint member and the shoulder of the shaft member form a tapered shape, the angle of each tapered shape with respect to the axis is the taper angle, and the small-diameter end of the female spline is the shaft member. The constant velocity universal joint according to claim 1, wherein the shoulder portion is brought into contact with the shoulder portion at the same taper angle. The cut-out end of the male spline of the shaft member and the shoulder of the shaft member form a taper shape in which one of them has a smaller diameter toward the other side, and the angle of each part of the taper shape with respect to the axis is defined as the taper angle. The constant velocity universal joint according to claim 1 or 2, wherein the taper angle of the cut-out end portion is smaller than the taper angle of the shoulder portion.

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