JP2018003989A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a diameter of raw material for a shaft by a convenient structure and reduce cost of a constant velocity universal joint.SOLUTION: This invention relates to a constant speed universal joint comprising an outer joint member and an inner joint member 12 for transmitting a rotational torque between it and the outer joint member through balls while allowing an angular displacement in which a shaft 20 is inserted into a shaft hole 27 of the inner joint member 12 and the inner joint member 12 and the shaft 20 are connected in spline fitting to enable a torque transmission to be carried out. A male spline 28 formed at an outer peripheral surface of the shaft 20 is cut through, a shoulder part 36 having a smaller outer diameter than that of a large diameter part 35 of the male spline 28 is formed at an outer peripheral surface of the shaft 20 and a small diameter end part 38 of a female spline 29 formed at the inner peripheral surface of the shaft hole 27 of the inner joint member 12 is abutted against a shoulder 36 of the shaft 20.SELECTED DRAWING: Figure 2

Description

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

  There are two types of constant velocity universal joints that are used as means for transmitting rotational force from an automobile engine to a wheel at a constant speed: 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 so that rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle.

  A drive shaft that transmits power from the engine to the wheels needs to cope with angular displacement and axial displacement caused by a change in the relative positional relationship between the engine and the wheels. Therefore, the drive shaft is generally equipped with a sliding type constant velocity universal joint on the engine side (inboard side) and a fixed type 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 type constant velocity universal joint is connected to the shaft hole of the inner joint member of the fixed type constant velocity universal joint so that torque can be transmitted by spline fitting.

  Conventionally, various structures have been proposed as a connection structure between an inner joint member of a fixed type constant velocity universal joint and a shaft in this drive shaft (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 the inner peripheral surface of the shaft hole 127 of the inner joint member 112. A 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 connected 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 131 is open on the end surface of the inner joint member 112.

  A retaining ring 132 is fitted into the annular groove 130 of the shaft 120, and the retaining ring 132 is locked to the step portion 131 of the inner joint member 112, thereby preventing the shaft 120 from coming off from the inner joint member 112. Yes.

On the other hand, 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 as shown in FIG. A shoulder 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 position slightly away from the raised end portion 134 of the male spline 128. (D ₁ <d ₂ ).

  By bringing the end surface 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 surface portion 141 is a tapered portion from the end surface of the inner joint member 112 to the stealing portion 137.

  As described above, the retaining ring 132 of the annular groove 130 of the shaft 120 is locked to the stepped portion 131 of the inner joint member 112, thereby preventing the shaft 120 from coming off from the inner joint member 112 and the shaft 120. The shaft 120 and the inner joint member 112 are assembled by restraining the inner joint member 112 in the axial direction by bringing the end face portion 141 of the inner joint member 112 into contact with the shoulder 136.

Japanese Patent No. 4271301

  By the way, in the connection structure of the inner joint member 112 and the shaft 120 described above, the end surface portion 141 of the inner joint member 112 is attached to the shoulder 136 at a position slightly away from the rounded-up end portion 134 of the male spline 128 of the shaft 120. Since the inner joint member 112 is restrained in the axial direction by abutting, it has the following problems.

  Here, in a constant velocity universal joint, in order to prevent lubricant leakage from the inside of the joint and entry of foreign matter from the outside of the joint, it is common to install a boot between the outer joint member and the shaft 120. Therefore, as shown in FIG. 9, the small-diameter end of the boot is fastened and fixed to the protrusion 125 of the shaft 120 by a boot band.

In assembling the boot to the shaft 120, the shoulder portion 136 of the shaft 120 is passed through the small-diameter end portion of the boot, and the small-diameter end portion is fixed to the protruding portion 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. .

  The manufacture of the shaft 120 requires a material having an outer diameter including a cutting allowance for forming the protrusion 125 that is the maximum diameter of the shaft 120. For this reason, the material diameter of the shaft 120 is restricted, and it is difficult to reduce the material diameter and to reduce the cost.

  Therefore, the present invention has been proposed in view of the above-described improvements, and an object of the present invention is to provide a constant velocity universal joint that can reduce the material diameter of the shaft with a simple structure and reduce costs. There is.

  A 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 between the outer joint member and the outer joint member via the torque transmission member. A shaft member is inserted into the shaft hole of the member, and the inner joint member and the shaft member are coupled to each other so as to transmit torque by spline fitting.

  As technical means for achieving the aforementioned object, the present invention provides a male spline formed on the outer peripheral surface of the shaft member as a cut-out shape, and a shoulder portion having an outer diameter smaller than the large diameter portion of the male spline. A small-diameter end portion of a 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-off shape, and the small-diameter end of the female spline of the inner joint member is in contact with the shoulder of the shaft member. It becomes possible to make it smaller than before. In this way, by reducing the outer diameter of the shoulder portion that is passed through the small-diameter end portion of the boot, the outer diameter of the protrusion that fixes the small-diameter end portion of the boot, that is, the maximum diameter of the shaft member is made smaller than before. can do.

  In the present invention, a structure in which a stealing portion is formed in the female spline of the inner joint member and a small-diameter end portion of the female spline located in the stealing portion is in contact with the shoulder portion of the shaft member is desirable.

  If such a structure is adopted, the outer diameter of the shoulder portion passed through the small diameter end portion of the boot is further increased by bringing the small diameter end portion of the female spline located at the stealing portion into contact with the shoulder portion of the shaft member. This 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 are tapered, and the small-diameter end of the female spline is in contact with the shoulder of the shaft member at the same taper angle. Is desirable.

  If such a structure is adopted, the axial position of the shoulder portion of the shaft member can be accurately ensured by bringing the small diameter end portion of the female spline into contact with the shoulder portion of the shaft member at the same taper angle. .

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

  By adopting such a structure, even if it is a male spline with a cut-out shape whose torsional strength is lower than the rounded-up shape, the taper angle of the cut-out end portion is made smaller than the taper angle of the shoulder portion. The stress concentration at the cut-out end of the can be alleviated.

  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 in contact with the shoulder of the shaft member. It becomes possible to make the outer diameter of the shoulder part of the shaft member made smaller than before. Thereby, the outer diameter of the protrusion part which fixes the small diameter edge part of a boot, ie, the maximum diameter of a 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.

In embodiment of this invention, it is sectional drawing which shows the connection structure of an inner joint member and a shaft. It is an expanded sectional view which shows the A section of FIG. It is sectional drawing which shows the connection structure of an inner joint member and a shaft in other embodiment of this invention. It is an expanded sectional view which shows the B section of FIG. It is sectional drawing which shows the connection structure of an inner joint member and a shaft in other embodiment of this invention. It is an expanded sectional view which shows the C section of FIG. It is a block diagram which shows the point which carries out the turning simultaneously of the annular ditch | groove and shoulder part of the shaft of FIG. It is sectional drawing which shows the whole structure of a constant velocity universal joint. It is sectional drawing which shows the conventional connection structure of an inner side coupling member and a shaft. It is an expanded sectional view which shows the D section of FIG.

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

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

  A drive shaft incorporated in an automobile such as a 4WD vehicle or an FR vehicle needs to cope with angular displacement and axial displacement caused by a change in the relative positional relationship between the engine and wheels. Therefore, the drive shaft is generally equipped with a sliding type constant velocity universal joint on the engine side (inboard side) and a fixed type 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 type 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 as shown in FIG. The plurality of balls 13 and the cage 14 constitute a main part.

  In the outer joint member 11, arc-shaped track grooves 15 extending in the axial direction are formed at a plurality of positions in the circumferential direction of the spherical inner peripheral surface 16 at equal intervals. In the inner joint member 12, arc-shaped 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 positions in the circumferential direction of the spherical outer peripheral surface 18 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 and transmits rotational torque. The cage 14 is disposed 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 any number, and the number is arbitrary.

  In the constant velocity universal joint configured as described above, when an operating angle (angular displacement of the shaft 20 with respect to the outer joint member 11) is applied, the ball 13 held by the cage 14 always has an operating angle at any operating angle. Is maintained in the bisection plane, and the constant velocity of the joint is ensured.

  In this constant velocity universal joint, a lubricant such as grease is sealed in the inner space of the outer joint member 11, so that when the joint is operated, the inner joint with respect to the sliding portion inside the joint, that is, the outer joint member 11 is operated. Lubricity at the sliding portion of the internal parts composed of the member 12, the ball 13 and the cage 14 is ensured.

  This constant velocity universal joint is provided with 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 enclosed in the joint and prevent foreign matter from entering from the outside of the joint. A structure in which a resin or rubber bellows-like 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 a 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. Fastened 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 so that torque can be transmitted by spline fitting. As shown in FIG. 1, the connecting structure between the inner joint member 12 and the shaft 20 is formed with a male spline 28 on the outer peripheral surface of the end portion of the shaft 20 and on the inner peripheral surface of the shaft hole 27 of the inner joint member 12. A female spline 29 is formed, and 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 connected 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. A retaining ring 32 is fitted into the annular groove 30 of the shaft 20, and the retaining ring 32 is engaged with the step portion 31 of the inner joint member 12, thereby preventing the shaft 20 from coming off from the inner joint member 12. Yes.

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 extracted from the outer peripheral surface of the shaft 20. A shoulder 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 position slightly away from the cut-out end portion 34 of the male spline 28. (D ₁ > D ₂ ).

  As shown in FIG. 2, a stealing portion 37 is formed in a female spline 29 extending in the axial direction from the end surface portion 41 of the inner joint member 12. The small-diameter end portion 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. Thereby, the inner joint member 12 is restrained in the axial direction so as not to move to the side opposite to the end of the shaft 20. Here, the aforementioned end surface portion 41 is a tapered portion from the end surface of the inner joint member 12 to the stealing portion 37.

  As described above, the retaining ring 32 of the annular groove 30 of the shaft 20 is locked to the step portion 31 of the inner joint member 12, thereby preventing the shaft 20 from coming off from the inner joint member 12 and the shaft 20. The shaft 20 and the inner joint member 12 are assembled by restraining the inner joint member 12 in the axial direction by bringing the small-diameter end portion 38 of the female spline 29 of the inner joint member 12 into contact with the shoulder portion 36. .

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 portion 38 of the female spline 29 of the inner joint member 12 is in contact with the shoulder portion 36 of the shaft 20. Thus, 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 is larger than the outer diameter d ₁ of the male spline 128 (d ₂ > d ₁ ). In the constant velocity universal joint (see FIG. 2) of this embodiment, 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 larger than 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 that is 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 fastened 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). (D ₃ <d ₃ ).

  As a result, the material diameter of the shaft 20 having an outer diameter including a machining allowance for forming the protrusion 25 that is the maximum diameter of the shaft 20 is reduced without being restricted by the material diameter of the shaft 20. Therefore, the cost of the constant velocity universal joint can be reduced.

  In the connection structure between the inner joint member 12 and the shaft 20, the contact surface between the small diameter end portion 38 of the female spline 29 of the inner joint member 12 and the shoulder portion 36 of the shaft 20 forms a taper shape. The small diameter end portion 38 of the female spline 29 is brought into contact with the shoulder portion 36 of the shaft 20 at the same taper angle α. That is, the taper angle α of the small-diameter end portion 38 of the female spline 29 and the taper angle α of the shoulder portion 36 of the shaft 20 are the same.

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

  As shown in FIG. 7, the annular groove 30 and the shoulder portion 36 of the shaft 20 are processed by simultaneous turning with chips 54 and 55 supported by holders 52 and 53 on a slide stage 51. By this simultaneous turning process, 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 can be ensured with high accuracy.

  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 of this embodiment (see FIG. 2), the shaft Twenty male splines 28 are cut out. 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. Therefore, the structure shown in FIGS. 3 and 4 is effective.

  In the constant velocity universal joint of the embodiment shown in FIGS. 3 and 4, in the connection structure between 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 thereof. The taper angle β of 39 is smaller than the taper angle α of the shoulder 36 (β <α).

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

  That is, since the axial dimension in which the height of the large-diameter portion (tooth tip portion) 35 of the male spline 28 gradually decreases at the cut-out end portion 39 of the male spline 28, it acts on the cut-out end portion 39 of the male spline 28. Load is distributed. Therefore, the stress concentration at the cut-out end 39 of the male spline 28 can be relaxed. This relaxation of the stress concentration can suppress a decrease in torsional strength.

  In the above embodiment, a structure in which the stealing portion 37 is formed in the female spline 29 of the inner joint member 12 and the small-diameter end portion 38 of the female spline 29 located in the stealing portion 37 is in 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 39 of the male spline 28.

  In the constant velocity universal joint of the embodiment shown in FIGS. 5 and 6, the stealing portion 37 (see FIGS. 3 and 4) is not formed in the female spline 29 of the inner joint member 12. In the connection structure between the inner joint member 12 and the shaft 20, the small-diameter end portion 40 of the female spline 29 extending in the axial direction from the end surface portion 41 of the inner joint member 12 is brought into contact with the shoulder portion 36 of the shaft 20.

  Here, when the female spline 29 does not have the stealing portion 37, when the fitting start position of 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 be reduced.

  However, as in the embodiment shown in FIGS. 5 and 6, even if the female spline 29 has no stealing portion 37 by increasing the axial dimension of the cut-off end portion 39 of the male spline 28, the inner joint 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 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 can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited 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
27 Shaft hole 28 Male spline 29 Female spline 36 Shoulder portion 37 Stealing portion 38 Small diameter end portion 39 Cut-out end portion

Claims (4)

An outer joint member and an inner joint member that transmits rotational torque while allowing angular displacement between the outer joint member and the outer joint member, 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 as to transmit torque by spline fitting,
The male spline formed on the outer peripheral surface of the shaft member has 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, and the shaft hole of the inner joint member A constant velocity universal joint characterized in that a small-diameter end of a female spline formed on the inner peripheral surface of the shaft is in contact with the shoulder of the shaft member.   The constant velocity universal joint according to claim 1, wherein a stealing portion is formed in the female spline of the inner joint member, and a small-diameter end portion of the female spline located in the stealing portion is brought into contact with a shoulder portion of the shaft member.   The small-diameter end of the female spline of the inner joint member and the shoulder of the shaft member are tapered, and the small-diameter end of the female spline is in contact with the shoulder of the shaft member at the same taper angle. Or the constant velocity universal joint of 2.   The constant velocity universal joint according to any one of claims 1 to 3, wherein a cutout end portion of the male spline of the shaft member has a tapered shape, and a taper angle of the cutout end portion is smaller than a taper angle of a shoulder portion. .

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