JP7142593B2 - Outer joint member for constant velocity universal joint - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer joint member of a constant velocity universal joint that is incorporated in a power transmission system of, for example, an automobile or various industrial machines, and that transmits rotational power at a constant speed between two shafts on the driving side and the driven side.

As is well known, constant velocity universal joints are roughly classified into fixed type constant velocity universal joints that allow only angular displacement and sliding type constant velocity universal joints that allow angular displacement and axial displacement. A constant velocity universal joint, regardless of whether it is a fixed type or a sliding type, includes an outer joint member having a cup portion and a shaft portion, and a plurality of guide grooves provided on the inner diameter surface of the cup portion; It includes, as main constituent members, joint internal parts such as an inner joint member and a torque transmission member that are housed in the inner periphery of the cup portion.

By the way, automobiles and various industrial machines are equipped with many electrical devices, and there is a possibility that current leaked from a power supply (battery) or an electrical system may flow into a constant velocity universal joint. For example, an electric vehicle 100 as schematically shown in FIG. 7, that is, a motor 102 is driven by a current E supplied from a battery 101, and receives its rotational power to drive a drive shaft 103 as a power transmission device and further drive wheels. In the electric vehicle 100 in which the (front wheels) 104 are rotationally driven, when part of the current E supplied from the battery 101 leaks from the motor 102, the leaked current E' is transferred to other parts (not shown) as shown in FIG. It flows into the outer joint member 111 of the sliding constant velocity universal joint (the illustrated example is a tripod type constant velocity universal joint) 110 that constitutes the drive shaft 103 via a member (for example, the side gear of the differential gear), and thereafter torque transmission. The members (rollers) 112→the inner joint members (tripod members) 113→the intermediate shaft 115→the inner joint members 123 of the fixed constant velocity universal joint 120→the torque transmission members (balls) 122→the outer joint members 121 flow in this order.

Although not shown, for example, in an automobile equipped with an electric brake for applying braking force to the drive wheels, if a portion of the current supplied to the electric brake leaks, the leakage current will be as described above. may flow through the drive shaft in the opposite direction.

When a leakage current (hereinafter simply referred to as "current") flows through the drive shaft as described above, for example, the contact portion between the outer joint member and the other member, the outer joint member (and the inner joint member) There is a risk that sparks generated at the contact portion between the torque transmission member and the torque transmission member may cause electrolytic corrosion, which may significantly reduce the durability life of the constant velocity universal joint. In recent years, the electrification of automobiles has progressed rapidly, and the possibility of electric current flowing into constant velocity universal joints has increased. there is

Therefore, the inventors of the present invention have found that electric corrosion of the constant velocity universal joint can be prevented by blocking the flow of current in the outer joint member to which the current is input from the outside of the joint. thought to be effective above. As a technical means for preventing current from flowing through the outer joint member, for example, one disclosed in Patent Document 1 below is known. That is, in Patent Document 1, the surface of the guide groove provided in the outer joint member is formed with a ceramic material as an insulating material (the guide groove is coated with a ceramic coating), and the entire outer joint member is formed with a ceramic material. etc. is described.

Japanese Utility Model Laid-Open No. 6-28351

However, during operation of the constant velocity universal joint (during torque transmission between the outer joint member and the inner joint member), high surface pressure is repeatedly applied to the surfaces of the guide grooves. Therefore, the ceramic coating covering the guide groove is easily damaged, peeled off, etc., and it may not be possible to appropriately prevent electrolytic corrosion of the constant velocity universal joint. In addition, if the entire outer joint member is made of a ceramic material, the cost of the outer joint member is significantly increased, and the mechanical strength required for the outer joint member is insufficient, adversely affecting the torque transmission performance of the constant velocity universal joint. may affect

In view of the above circumstances, an object of the present invention is to realize an outer joint member that can effectively prevent electrolytic corrosion of a constant velocity universal joint while having the required torque transmission performance. It is intended to contribute to improving the durability and reliability of a quick universal joint.

The present invention, which has been devised to achieve the above object, provides a cup portion having a plurality of guide grooves on an inner diameter surface in which a torque transmission member rolls, and a shaft extending axially outward from the bottom portion of the cup portion. an outer joint member for a constant velocity universal joint, wherein the shaft portion is provided with a connecting element for connecting another member in a torque-transmissible manner, the metal first member having the plurality of guide grooves; and an insulating member made of an insulating material is interposed between the second member made of metal and the connecting element, and the insulating member holds the first member and the second member in a non-contact state. , the first member and the second member are rotatable together. The "connecting element" used in the present invention includes splines and serrations in which axially extending convex portions (teeth) and concave portions (tooth bottoms) are alternately formed in the circumferential direction.

According to the above configuration, even if a current is input to the outer joint member via (the second member having) the connecting element, the insulation is interposed between the first member and the second member to hold them out of contact. The member blocks current transfer from the second member to the first member. As a result, the current transmission from the first member having the guide groove to the torque transmission member, and further the current transmission from the torque transmission member to the inner joint member, etc. can be naturally prevented, so that electrolytic corrosion of the constant velocity universal joint can be prevented. can be effectively prevented. On the other hand, a plurality of guide grooves in which the torque transmission member rolls and coupling elements for torque transmission are provided in the first and second metal members, respectively, and the insulating member is provided with the first and second members. Since it can rotate integrally, the mechanical strength and torque transmission performance required for the outer joint member can be ensured without any problem.

In the above configuration, each of the first member, the second member, and the insulating member may have a tubular portion forming a cup portion. In this case, the inner diameter surface of the tubular portion of the insulating member is fitted to the outer diameter surface of the tubular portion of the first member provided with a plurality of guide grooves on the inner diameter surface, and the tubular portion of the second member is fitted. can be fitted to the outer diameter surface of the cylindrical portion of the insulating member. At this time, the inner diameter surface of the tubular portion of the insulating member and the outer diameter surface of the tubular portion of the first member fitted thereto, and the outer diameter surface of the tubular portion of the insulating member and the first member fitted thereto. The relative rotation between the first member and the insulating member and the relative rotation between the insulating member and the second member can be restricted by forming the inner diameter surfaces of the cylindrical portions of the two members (both of them) to have a non-perfect circular cross section. Therefore, stable torque transmission becomes possible.

The outer joint member according to the present invention includes a first engaging member axially engaged with the tubular portion of the first member and the tubular portion of the insulating member, the tubular portion of the insulating member and the tubular portion of the second member. A second engagement member axially engaged with the projection may also be provided. With this configuration, it is possible to restrict the axial relative movement of the first member and the insulating member and the axial relative movement of the insulating member and the second member. It is possible to prevent the outer joint member from being disassembled or the like due to the axial load acting on.

The axial dimension of the tubular portion of the insulating member and the tubular portion of the second member can be smaller than the axial dimension of the tubular portion of the first member. This is advantageous in preventing the weight of the outer joint member from increasing due to the provision of the insulating member (the outer joint member being composed of a plurality of members).

As described above, according to the present invention, it is possible to realize an outer joint member that can effectively prevent electrolytic corrosion of a constant velocity universal joint while having required torque transmission performance. Thereby, the durability and reliability of the constant velocity universal joint can be improved.

FIG. 2 is a cross-sectional view showing an example of a drive shaft; (a) is a transverse cross-sectional view of an outer joint member according to an embodiment of the present invention [cross-sectional view along line AA in FIG. (b)], and (b) is a longitudinal cross-sectional view of the outer joint member. be. Fig. 3 is an exploded perspective view of the outer joint member shown in Fig. 2; (a) is a vertical cross-sectional view of an assembly of a first member and an insulating member that constitute the outer joint member shown in FIG. 2, and (b) is a vertical cross-sectional view of a second member. Fig. 10 is a vertical cross-sectional view of an assembly of a first member and an insulating member that constitute an outer joint member according to another embodiment of the present invention; It is a longitudinal section of the 2nd member which constitutes the outside joint member concerning other embodiments of the present invention. 1 is a schematic diagram of an electric vehicle; FIG. FIG. 10 is a diagram for explaining how a current (leakage current) flows through a conventional drive shaft;

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings (FIGS. 1 to 6).

FIG. 1 shows an example of a drive shaft 1, which is a type of power transmission device. The drive shaft 1 transmits rotational power (torque) output from a rotational drive source such as an engine or an electric motor to drive wheels, and is arranged on the inboard side (right side of the paper surface of FIG. 1). a constant velocity universal joint 3, a fixed constant velocity universal joint 10 arranged on the outboard side (left side of the paper surface of FIG. 1), and an intermediate shaft 2 connecting both constant velocity universal joints 3 and 10 so that torque can be transmitted. Prepare.

The sliding constant velocity universal joint 3 shown in FIG. It has a member 8 and a roller 7 as a torque transmission member. The tripod member 8 is provided with three leg shafts extending in the radial direction at equal intervals in the circumferential direction, and one roller 7 is rotatably fitted to the outer circumference of each leg shaft.

A fixed constant velocity universal joint 10 shown in FIG. A plurality of balls 15 as torque transmission members arranged between the cup portion 12 and the inner joint member 14, and arranged between the inner diameter surface of the cup portion 12 and the outer diameter surface of the inner joint member 14 to hold the balls 15. and a retainer 16 for holding. Another type of fixed constant velocity universal joint such as an undercut-free type may be used as the fixed constant velocity universal joint 10 .

Male splines are provided on the outer peripheral surfaces of the inboard and outboard ends of the intermediate shaft 2 . A male spline (not shown) on the inboard side is fitted into a female spline (not shown) provided in a hole of the tripod member 8 of the sliding constant velocity universal joint 3. The male spline is fitted into a female spline provided in the hole of the inner joint member 14 of the fixed constant velocity universal joint 10 . With such a configuration, torque is transmitted between the tripod member 8 and the intermediate shaft 2 and between the intermediate shaft 2 and the inner joint member 14 .

Lubricant such as grease is sealed inside both constant velocity universal joints 3 and 10 . In order to prevent external leakage of the lubricant and entry of foreign matter from the outside of the joint, the outer joint member 4 and the intermediate shaft 2 of the sliding constant velocity universal joint 3 and the outer joint member 11 of the fixed constant velocity universal joint 10 are provided. and intermediate shaft 2, cylindrical boots 9 and 17 are mounted respectively.

Hereinafter, an outer joint member to which the present invention is applied, here, an outer joint member 4 of a sliding constant velocity universal joint (tripod type constant velocity universal joint) 3 will be described in detail.

As shown in FIG. 2B , the outer joint member 4 includes a bottomed tubular cup portion 5 and a shaft portion 6 extending axially outward from the bottom portion of the cup portion 5 . A connecting element (here, a male spline) for connecting another member (for example, a side gear of a differential) and the outer joint member 4 so that torque can be transmitted is provided on the outer diameter surface of the free end side of the shaft portion 6. 23 are formed. As shown in FIG. 2( a ), guide grooves 21 for guiding the rolling of the roller 7 are formed at three circumferentially spaced locations on the inner diameter surface of the cup portion 5 . Each guide groove 21 has a pair of roller guide surfaces 22, 22 facing each other, and is formed in a linear shape extending in the axial direction, including the roller guide surfaces 22, 22 as well. The cup portion 5 of the present embodiment has a non-perfect circular cross section, more specifically, a corolla shape configured by alternately arranging three large-diameter portions and three small-diameter portions in the circumferential direction. The groove bottom surface of the guide groove 21 is formed by the inner diameter surface of the diameter portion.

As also shown in FIG. 3, the outer joint member 4 of the present embodiment is composed of an assembly of a first member 31, a second member 32 and an insulating member 33. The insulating member 33 is made of an insulating material. The main feature is that torque can be transmitted between the first member 31 and the second member 32 of . As the insulating material, ceramics having high hardness and excellent heat resistance and corrosion resistance are preferably used. A steel material having a carbon content of 0.20 to 0.60% by mass (carburized steel, medium carbon steel, alloy steel, etc.) with good penetration is preferably used.

As shown in FIGS. 2(b) and 4(a), the first member 31 has a bottomed cylindrical shape integrally including a cylindrical portion 31a having a guide groove 21 on the inner diameter surface and a bottom portion 31b. The insulating member 33 is formed in a bottomed tubular shape integrally having a tubular portion 33a and a bottom portion 33b. As shown in FIG. 2( a ), the cylindrical portion 31 a of the first member 31 and the cylindrical portion 33 a of the insulating member 33 both have a non-perfect circular cross-sectional shape (corolla-like shape) following the cross-sectional shape of the cup portion 5 . ), and the inner diameter surface of the tubular portion 33a is fitted to the outer diameter surface of the tubular portion 31a formed in the same kind of non-perfect circular shape. Thereby, since the first member 31 and the insulating member 33 are engaged in the circumferential direction (the rotation direction of the outer joint member 4), both the members 31 and 33 can rotate integrally. In addition, in order to prevent torque transmission performance from deteriorating due to relative rotation and relative movement in the axial direction between the first member 31 and the insulating member 33 during operation of the constant velocity universal joint 3, the inner diameter surface of the tubular portion 33a of the insulating member 33 is may be fixed to the outer diameter surface of the tubular portion 31a of the first member 31 by appropriate means (for example, press-fitting, adhesion, press-fitting adhesion, etc.).

As shown in FIGS. 2(b) and 4(b), the second member 32 integrally has a cup-shaped portion 32c integrally having a tubular portion 32a and a bottom portion 32b, and the shaft portion 6. As shown in FIG. As shown in FIG. 2( a ), the cylindrical portion 32 a is formed in a non-perfect circular cross-sectional shape (corolla shape) following the cross-sectional shape of the cup portion 5 , and is formed in the same non-perfect circular shape. The inner diameter surface of the tubular portion 32 a of the second member 32 is fitted to the outer diameter surface of the tubular portion 33 a of the insulating member 33 . As a result, the insulating member 33 and the second member 32 are engaged in the circumferential direction, so that the second member 32 and the insulating member 33, as well as the first member 31, the second member 32 and the insulating member 33, can rotate together. . In addition, in order to prevent torque transmission performance from deteriorating due to relative rotation and relative movement in the axial direction between the second member 32 and the insulating member 33 during operation of the constant velocity universal joint 3, the inner diameter of the cylindrical portion 32a of the second member 32 is The surface may be fixed to the outer diameter surface of the cylindrical portion 33a of the insulating member 33 by appropriate means (for example, press-fitting, adhesion, press-fitting adhesion, etc.).

With the above configuration, the tubular portion 33a of the insulating member 33 is interposed between the tubular portion 31a of the first member 31 and the tubular portion 32a of the second member 32, and the bottom portion 31b of the first member 31 and the second Since the bottom portion 33b of the insulating member 33 is interposed between the bottom portion 32b of the member 32, the first member 31 and the second member 32 are kept in a non-contact state.

Summarizing the above, in the outer joint member 4, the metal first member 31 having the guide groove 21 and the connecting element (male spline) for connecting the other member and the outer joint member 4 so that torque can be transmitted. An insulating member 33 made of an insulating material is interposed between the second member 32 made of metal and the insulating member 33, and the insulating member 33 holds the first member 31 and the second member 32 in a non-contact state. It is integrally rotatable with the first member 31 and the second member 32 .

According to such a configuration, even if a current is input to (the second member 32 constituting) the outer joint member 4 via another member, the insulating member interposed between the first member 31 and the second member 32 33 blocks current transfer from the second member 32 to the first member 31 . As a result, the current transmission from the first member 31 having the guide groove 21 to the rollers 7 and the current transmission from the rollers 7 to the tripod members 8 can be prevented, so that the constant velocity universal joint 4 is prevented from being subjected to electrolytic corrosion. can be effectively prevented. On the other hand, the guide groove 21 in which the roller 7 rolls and the connecting element 23 are provided on the first member 31 and the second member 32 made of metal, respectively. Since it is integrally rotatable, the mechanical strength and torque transmission performance required for the outer joint member 4 can be ensured without any problem.

Therefore, according to the present invention, it is possible to realize the outer joint member 4 that can effectively prevent electrolytic corrosion of the constant velocity universal joint 3 while having the required torque transmission performance. Thereby, the durability and reliability of the constant velocity universal joint 3 can be improved.

As shown in FIGS. 2(b), 3 and 4(a), the outer joint member 4 of the present embodiment is axially aligned with the tubular portion 31a of the first member 31 and the tubular portion 33a of the insulating member 33. and a second engaging member 35 axially engaged with the tubular portion 33 a of the insulating member 33 and the tubular portion 32 a of the second member 32 .

The first engaging member 34 is configured by a clip having ends in the circumferential direction (so-called C-shaped clip), and includes an annular groove 31c provided on the outer diameter surface of the cylindrical portion 31a of the first member 31 and an annular groove 31c. is fitted and fixed in an annular gap defined by an annular groove 33c provided on the inner diameter surface of the cylindrical portion 33a of the insulating member 33 so as to face the . The second engaging member 35 is composed of a C-shaped clip similar to the first engaging member 34, and has an annular groove 33d provided on the outer diameter surface of the cylindrical portion 33a of the insulating member 33 and an annular groove 33d. is fitted and fixed in an annular gap defined by an annular groove 32d provided on the inner diameter surface of the tubular portion 32a of the second member 32 so as to face the second member 32. As shown in FIG.

Since the outer joint member 4 further includes the first and second engaging members 34 and 35, the axial positioning of the first member 31 and the insulating member 33 required when assembling the outer joint member 4, And the axial positioning of the insulating member 33 and the second member 32 can be performed easily and accurately. and the second member 32 can be effectively prevented from moving relative to each other in the axial direction. As a result, the torque transmission performance of the outer joint member 4 made up of a plurality of members can be improved, so the reliability of the constant velocity universal joint 3 can be further enhanced.

In addition, the outer joint member 4 according to the present invention is a metal outer joint member that does not have the insulating member 33 because the insulating member 33 is interposed between the metal first member 31 and the second member 32. There is a possibility that the weight will be increased compared to the member. If the weight of the outer joint member is increased, the weight of the constant velocity universal joint and further the drive shaft is increased, and there is a concern that the fuel consumption (electricity consumption) of the automobile is deteriorated. Therefore, in the outer joint member 4 of the present embodiment, the axial dimension of the tubular portion 32a of the second member 32 and the tubular portion 33a of the insulating member 33 is set to be greater than the axial dimension of the tubular portion 31a of the first member 31. Weight is also suppressed by making it smaller.

As mentioned above, although the outer joint member 4 which concerns on one Embodiment of this invention was demonstrated, embodiment of this invention is not restricted to this.

For example, as shown in FIG. 5, the first member 31 and the insulating member 33 can be replaced with bottoms 31b and 33b having holes (through-holes) opening at both end surfaces thereof. Further, as shown in FIG. 6, the second member 32 has a hole (through hole) that opens to the inner bottom surface of the bottom portion 32b and the end surface (the end surface on the free end side) of the shaft portion 6, and has a constant velocity universal joint. 3 (outer joint member 4) and another member can be replaced with one provided on the inner diameter surface of the shaft portion 6 (inner wall surface of the hole portion).

In the above description, the insulating member 33 formed in a cylindrical shape with a bottom is used. As long as it can rotate integrally with 31 and the second member 32, it can take any shape. Therefore, although illustration is omitted, the insulating member 33 can be formed in a disc shape, for example.

Although the case where the present invention is applied to the outer joint member 4 of the tripod type constant velocity universal joint among the sliding constant velocity universal joints 3 has been described above, the present invention is applicable to other types of sliding constant velocity universal joints. It can also be applied to the outer joint member of a universal joint, for example, a double offset type constant velocity universal joint or a cross groove type constant velocity universal joint. Furthermore, the present invention is applied not only to the outer joint member of a sliding constant velocity universal joint, but also to the outer joint member of a fixed constant velocity universal joint (for example, the Barfield type or undercut-free type shown in FIG. 1). is also possible.

The present invention is by no means limited to the above-described embodiments, and can be embodied in various forms without departing from the gist of the present invention. That is, the scope of the present invention is indicated by the claims, and includes equivalent meanings and all changes within the scope of the claims.

REFERENCE SIGNS LIST 1 drive shaft 3 sliding constant velocity universal joint 4 outer joint member 5 cup portion 6 shaft portion 7 roller (torque transmission member)
31 first member 31a tubular portion 32 second member 32a tubular portion 33 insulating member 33a tubular portion 34 first engaging member 35 second engaging member

Claims (3)

A cup portion having a plurality of guide grooves in which the torque transmission member rolls on an inner diameter surface, and a shaft portion extending axially outward from the bottom portion of the cup portion, wherein the shaft portion is provided with another member for torque transmission. An outer joint member for a constant velocity universal joint provided with a connecting element for communicably connecting,
An insulating member made of an insulating material is interposed between the first metal member having the plurality of guide grooves and the second metal member having the connecting element,
The insulating member is rotatable together with the first member and the second member while holding the first member and the second member in a non-contact state ,
Each of the first member, the second member, and the insulating member has a tubular portion forming the cup portion, and the inner diameter surface of the tubular portion of the insulating member is aligned with the inner diameter surface to form the plurality of guides. It is fitted to the outer diameter surface of the tubular portion of the first member provided with a groove, and the inner diameter surface of the tubular portion of the second member is fitted to the outer diameter surface of the tubular portion of the insulating member. are combined,
A first engaging member is provided between the tubular portion of the first member and the tubular portion of the insulating member and is axially engaged with the tubular portion of the insulating member and the tubular portion of the insulating member. An outer joint member for a constant velocity universal joint, characterized in that a second engaging member is provided between the cylindrical portion of the and the second engaging member axially engaged with both of them . The inner diameter surface of the tubular portion of the insulating member and the outer diameter surface of the tubular portion of the first member fitted thereto, and the outer diameter surface of the tubular portion of the insulating member and the above-mentioned 2. The outer joint member for a constant velocity universal joint according to claim 1 , wherein the inner diameter surface of the cylindrical portion of the second member is formed to have a non-perfect circular cross section. 3. The constant velocity universal joint according to claim 1 , wherein the axial dimension of the tubular portion of the insulating member and the tubular portion of the second member is smaller than the axial dimension of the tubular portion of the first member. Outer joint member.

Images