WO2018135205A1

WO2018135205A1 - Hollow power transmission shaft

Info

Publication number: WO2018135205A1
Application number: PCT/JP2017/045268
Authority: WO
Inventors: 裕一郎北村
Original assignee: Ntn株式会社
Priority date: 2017-01-18
Filing date: 2017-12-18
Publication date: 2018-07-26
Also published as: JP2018115704A

Abstract

Provided is a hollow power transmission shaft comprising a pair of shaft members and an intermediate cylinder interposed between the pair of shaft members and integrally joined to the shaft members, wherein a constant velocity universal joint is connected to an end of each of the shaft members. The axial lengths of the pair of shaft members are set at the same length. Each of the pair of shaft members has a cylindrical joint section, the inner and outer diameters of which are equal to the inner and outer dimensions of the intermediate cylinder.

Description

Hollow power transmission shaft

The present invention relates to a hollow power transmission shaft connected to a constant velocity universal joint or the like.

For example, in a power transmission system of an automobile, a power transmission shaft that transmits power from a reduction gear (differential) to driving wheels is used. A sliding type constant velocity universal joint is connected at one end of the power transmission shaft, and a fixed type constant velocity universal joint is connected at the other end of the power transmission shaft to constitute a drive shaft.

In this case, it is connected to the speed reducer side through a sliding type constant velocity universal joint, and is connected to the driving wheel side through the other end, a so-called fixed side constant velocity universal joint. As this power transmission shaft, a solid shaft has been widely used in the past and at present. However, in recent years, there has been a demand for hollowing out the power transmission shaft from the viewpoint of reducing the weight of the automobile, improving the function by increasing the rigidity of the power transmission shaft, and improving the quietness of the vehicle interior by optimizing the tuning of the primary natural frequency of bending. It is increasing.

Conventionally, for example, the pipe material is subjected to drawing processing to form a hollow shaft material having a large diameter portion in the axial middle portion and a small diameter portion on both axial side portions. After performing the required machining, a hollow power transmission shaft is manufactured by performing heat treatment (Patent Document 1).

Patent Document 2 discloses a hollow power transmission shaft (two-piece type) formed by joining and forming the hollow end surfaces of a pair of stub shafts formed by cold forging a solid bar. Discloses a hollow power transmission shaft (three-piece type) composed of a pair of stub shafts and a pipe material disposed between the stub shafts.

JP 2007-075824 A JP 2001-315539 A

The hollow power transmission shaft shown in Patent Document 1 is an integral hollow shaft. Such an integral hollow shaft is processed by a swaging process or the like. For this reason, a large amount of cost is required for mold costs, equipment costs and the like, and pipe material is used as the raw material. However, the cost of the pipe material is higher than that of the solid bar material, and the material cost is high.

For this reason, such an integrated hollow shaft is unsuitable for an intermediate shaft for vehicles of a large variety and a small volume production due to a high manufacturing cost, and is inferior in versatility. Also, after molding the shaft from pipe material, it is difficult to inspect the inner surface for scratches, defects, and size, which increases the man-hours for quality control of the entire shaft, making high-precision inspection difficult. Yes. In addition, when a manufacturing request is received from a customer, the trial time is required and the lead time is long.

Further, as described in Patent Document 2, in the three-piece type, the stub shaft and the pipe material have different shapes (diameter dimension, axial length) for each constant velocity universal joint, and for each vehicle. It is necessary to use it.

In other words, since it is necessary to tune the natural frequency of bending to cope with the demand for weight reduction, the vehicle vibration problem, and the rigidity value to prevent torque steer, etc. Will be needed. Correspondingly, various diameters are required for the diameter of the stem joint portion. For this reason, there were various stem and pipe specifications for each vehicle type. For this reason, the productivity is inferior and the cost is high.

Therefore, in view of the above problems, the present invention provides a hollow power transmission shaft that can achieve improvement in productivity, cost reduction, load reduction in production management, and the like.

The hollow power transmission shaft according to the present invention includes a pair of shaft members and an intermediate cylindrical body that is interposed between the pair of shaft members and integrally joined to each shaft member. A hollow power transmission shaft to which a speed universal joint is connected, wherein the pair of shaft members have the same axial length, and the pair of shaft members has inner and outer diameter dimensions of the intermediate cylindrical body. It has the cylindrical joint part which is the same.

According to the hollow power transmission shaft of the present invention, the shaft member (stem portion) has one specification for one joint size, and the shaft member (stem portion) can be integrated. In addition, as for the intermediate cylinder, it is only necessary to procure one inner and outer diameter for one joint size, and the intermediate cylinder can also be integrated into a variety. In this case, it is preferable that the pair of shaft members have the same specifications. By making the pair of shaft members have the same specification, it is possible to stably integrate the products.

The pair of shaft members includes a joint portion in which the outer diameter on the intermediate cylinder side is the same as the outer diameter of the intermediate cylinder body, a shaft member main body portion having a smaller diameter than the joint portion, and the shaft member main body portion and the joint portion. Where the outer diameter of the intermediate cylinder is D and the shaft member main body is d, D = 0.52 × d + C, and C is 15.92 to 23.09. It is preferable to do this. By setting in this way, a shaft corresponding to an existing (mass-produced) hollow power transmission shaft can be obtained.

The shaft member and the intermediate cylinder may be joined and integrated by electron beam welding or may be joined and integrated by laser welding. Here, electron beam welding uses thermoelectrons emitted by heating the cathode with a filament, and the thermoelectrons are accelerated using an electromagnetic field created by a voltage difference to collide with an object to be welded. In this method, welding is performed using the impact heat generated. Laser welding is a method of joining by irradiating a laser beam mainly on a metal as a heat source and locally melting and solidifying the metal.

It is preferable that the shaft member is composed of a forged product.

In the present invention, it is possible to integrate the types of the shaft member and the intermediate cylinder, thereby improving the productivity and reducing the cost. Moreover, the load of production management can be reduced by reducing the kind of member.

FIG. 3 is a half cut sectional view of a hollow power transmission shaft of the present invention using electron beam welding as a joining means. It is sectional drawing of the drive shaft using a hollow power transmission shaft. FIG. 3 is a half cut sectional view of a short hollow power transmission shaft of the present invention. FIG. 2 is a half cut sectional view of a long hollow power transmission shaft of the present invention. It is a half-cut sectional view of the hollow power transmission shaft of the present invention using laser welding as a joining means. It is a half-cut sectional view of the hollow power transmission shaft of the present invention using friction welding as a joining means. It is process drawing which shows the manufacturing method of the hollow-shaped power transmission shaft of this invention. It is a side view of the shaft member before a turning process. It is a block diagram which shows the kind integration example of a shaft member.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 2 shows a drive shaft using a hollow power transmission shaft according to the present invention. A fixed type constant velocity universal joint 1, a sliding type constant velocity universal joint 2, and a hollow power transmission shaft S for connecting these constant velocity universal joints are provided. In this example, a Barfield type constant velocity universal joint is used as a fixed type constant velocity universal joint, and a tripod type constant velocity universal joint is used as a sliding type constant velocity universal joint.

The fixed type constant velocity universal joint 1 includes an outer joint member 5 in which a plurality of track grooves 3 extending in the axial direction are formed on the inner spherical surface 4, and an inner side in which a plurality of track grooves 6 extending in the axial direction are formed on the outer spherical surface 7. A joint member 8, a plurality of balls 9 that are interposed between the track 3 of the outer joint member 5 and the track 6 of the inner joint member 8 and transmit torque, the inner spherical surface 4 of the outer joint member 5, and the inner joint member 8. And a cage 10 that holds the ball 9 interposed between the outer spherical surface 7 and the outer spherical surface 7.

The sliding type constant velocity universal joint 2 is provided with an outer joint member 12 provided with three grooves 11 extending in the axial direction on the inner periphery and provided with roller guide surfaces 11a opposed to each other on the inner wall of each groove 11, and a radial direction. A tripod member 14 as an inner joint member provided with three leg shafts 13 projecting on the shaft, and torque transmission means rotatably supported by the leg shaft 13 and inserted into the groove 11 of the outer joint member so as to roll. As a roller 15. In this case, the roller 15 is fitted onto the outer diameter surface of the leg shaft 13 via a plurality of rollers 16 disposed along the circumferential direction. The tripod member 14 includes a boss portion 17 and the leg shaft 13 extending from the boss portion 17 in the radial direction.

The hollow power transmission shaft S is formed with male splines (spline shafts) 21a and 21b at both ends thereof, and one male spline 21a is fitted into the inner joint member 8 of the fixed type constant velocity universal joint 1 and the other male spline 21a. The spline 21 b is fitted into the tripod member 14 of the sliding type constant velocity universal joint 2. A female spline (spline hole) 23 is formed in the shaft hole 22 of the inner joint member 8, and one male spline 21 a of the shaft S is fitted into the shaft hole 22 of the inner joint member 8, so that a female spline (spline hole) is formed. 23. Further, the other male spline (spline shaft) 21 b of the shaft S is fitted into the axial hole 24 of the boss portion 17 of the tripod member 14, and meshes with the female spline (spline hole) 25 of the axial hole 24.

The fixed type constant velocity universal joint 1 is provided with a boot 30A for sealing the opening of the outer joint member 5, and the sliding type constant velocity universal joint 2 is used for sealing the opening of the outer joint member 12. Boots 30B are attached. The

boots

30A and 30B include a large-diameter attachment portion 30a, a small-diameter attachment portion 30b, and a bellows portion 30c that constitutes a bent portion that connects the large-diameter attachment portion 30a and the small-diameter attachment portion 30b. The large-diameter mounting portion 30a of the

boots

30A and 30B is fastened and fixed by the fastening band 32 at the

boot mounting portions

31 and 31 formed on the outer diameter surface on the opening side of the outer joint members 12 and 5, and the small-diameter mounting portion. Reference numeral 30b denotes a predetermined portion of the shaft S (boot mounting portions 33, 33) that is fastened and fixed by a fastening band 32.

As shown in FIG. 1, the hollow power transmission shaft S includes a pair of shaft members 40 (40A, 40B) and an intermediate cylinder 41 interposed between the pair of shaft members 40 (40A, 40B). . The pair of shaft members 40 (40A, 40B) includes a main body portion 42 of the male spline 21a (21b) at the end, and a cylindrical joint portion in which the inner and outer diameter dimensions of the intermediate cylinder 41 are set to be the same. 43 and a tapered connecting portion 44 that connects the cylindrical joint portion 43 and the main body portion 42. In this case, the outer diameter of the main body 42 is set smaller than the outer diameter of the intermediate cylinder 41. Further, the pair of shaft members 40 (40A, 40B) is configured by a solid body other than the cylindrical joint portion 43, that is, the main body portion 42 and the connecting portion 44.

In addition to the

male splines

21a and 21b, circumferential

concave grooves

45 and 45 of the

boot mounting portions

33 and 33 are formed in the main body portion 42 of the pair of shaft members 40 (40A and 40B). Further, circumferential

concave grooves

48 and 48 into which retaining rings 46 and 47 (see FIG. 2) for retaining are provided are provided at the ends of the

male splines

21a and 21b.

The one shaft member 40A and the intermediate cylinder 41 are joined to each other by joining the end face 43a of the tubular joint portion 43 of the shaft member 40A and the one end face 41a of the intermediate cylinder 41 with each other. Further, the other shaft member 40B and the intermediate cylinder 41 are joined to each other by joining the end surface 43b of the cylindrical joint portion 43 of the shaft member 40B and the one end surface 41b of the intermediate cylinder 41 through a joining means. Yes. In this case, the joining means is electron beam welding. Here, electron beam welding uses thermoelectrons emitted by heating the cathode with a filament, and the thermoelectrons are accelerated using an electromagnetic field created by a voltage difference to collide with an object to be welded. In this method, welding is performed using the impact heat generated. In addition, Wa of FIG. 1 has shown the junction part W formed by electron beam welding.

In this shaft S, when the outer diameter of the intermediate cylinder 41 is D and the outer diameter of the shaft member main body 42 is d, D = 0.52 × d + C and C is 15.92 to 23.09. It is said. This dimension setting is based on the following Table 1.

Table 1 shows the relationship between the shaft portion diameter (the outer diameter of the main body portion of the shaft member) and the raw tube diameter (the outer diameter of the intermediate cylinder 41). D = 0.52 × d + 23.09 represents the upper limit of the mass-produced product of the existing tribe shaft, and D = 0.52 × d + 15.92 represents the lower limit of the mass-produced product of the existing tribe shaft. For this reason, if it sets to 0.52 * d + 15.92 <= D <= 0.52 * d + 23.09, it will respond to the mass-production goods of the existing tribe shaft.

By the way, as the hollow power transmission shaft S, if an intermediate cylinder 41 having different axial lengths is used, a so-called short hollow power transmission shaft S as shown in FIG. 3 or a so-called long length as shown in FIG. A hollow hollow power transmission shaft S can be configured. That is, the hollow power transmission shaft S shown in FIG. 3 and the hollow power transmission shaft S shown in FIG. 4 have the same length A (length in the axial direction) of each shaft member 40 (40A, 40B). When the axial length of the intermediate cylinder 41 of the hollow power transmission shaft S shown in FIG. 3 is L1, and the axial length of the intermediate cylinder 41 of the hollow power transmission shaft S shown in FIG. 4 is L2. In addition, L1 <L2. For this reason, by changing the intermediate cylinder 41, it is possible to configure the hollow power transmission shaft S having various lengths (lengths in the axial direction).

FIG. 5 shows a case where laser welding is used as the joining means. Here, laser welding is a method of joining by irradiating a laser beam mainly on a metal as a heat source and locally melting and solidifying the metal. In FIG. 5, Wb indicates a joint W formed by laser welding.

FIG. 6 shows a case where friction welding is used as the joining means. Here, the friction welding is a method in which members to be joined (for example, metal or resin) are rubbed together at high speed, and the members are softened by frictional heat generated at the same time, and at the same time, pressure is applied to join them. In FIG. 6, Wc indicates a joint W formed by friction welding.

Next, FIG. 7 shows the manufacturing process of the hollow power transmission shaft S. In this case, the manufacturing process of the stem material (shaft member 40), the manufacturing process of the raw pipe material (intermediate cylinder 41), and the stem material There is a step of joining the (shaft member 40) and the raw pipe material (intermediate cylinder 41).

The manufacturing process of the stem material (shaft member 40) includes a cutting process S1s, a forging process S2s, and a turning process S3s for cutting the bar material, which is a material, into a predetermined dimension (a predetermined axial length). Examples of materials include carburized materials with low carbon concentrations (SCr, SCM, etc.), medium carbon steels with carbon concentrations of 0.25% to 0.6% (S30c, S55C, etc.), alloy steels (SAE1535M, etc.), etc. is there. In the forging step S2s, the processed product shown in FIG. 8 is formed. That is, the shaft member 40S having no

male splines

21a and 21b and

circumferential grooves

45 and 48 is formed. Therefore, the shaft member 40 </ b> S includes a main body portion constituting portion 42 </ b> S constituting the main body portion 42, a joining portion constituting portion 43 </ b> S constituting the cylindrical joint portion 43, and a continuous portion constituting portion 44 </ b> S constituting the continuous portion 44. It consists of. For this reason, the outer diameter dimension ds of the main body part constituting part 42S is the same as the outer diameter dimension d of the main body part 42 of the formed shaft S, and the outer diameter dimension d1s of the joint part constituting part 43S is equal to that of the intermediate cylinder 41. It is set to be the same as the outer diameter dimension D.

The turning process S3s includes a male spline forming process, a circumferential groove forming process, and a joint forming process. In the male spline forming process, cutting is performed with the diameter (outer diameter) of the

spline

21a, 21b as the spline lower diameter, and the male spline 21 is formed by rolling (or pressing) the spline lower diameter. (21a, 21b) is formed. The circumferential groove forming step is a step of turning the circumferential groove. The joint formation process is a finishing process for the cylindrical joint 43. When the forging process S2s is not performed, outer diameter turning is performed.

The raw pipe material (intermediate cylinder) manufacturing process includes a raw pipe cutting process S1p and a turning process S2p. The raw tube cutting step S1p is a step of cutting a long raw tube into a predetermined dimension (predetermined axial length). The turning process S2p is a finishing process by turning a joint portion (a portion to be joined to the shaft member) of the intermediate cylinder.

The thus formed shaft member 40 (40A, 40B) and the intermediate cylinder part 41 perform a joining process (in this case, a welding process S4), and the intermediate cylinder part 41 is interposed between the pair of

shaft members

40A, 40B. The formed shaft S is formed. Thereafter, a heat treatment step S5 is performed. Examples of the heat treatment step S5 include carburizing quenching and induction quenching. Further, the heat treatment range may include the

male splines

21a and 21b, the

male splines

21a and 21b and the hollow portion, etc. over the entire length of the shaft S.

Incidentally, for example, as shown in FIG. 9, if a plurality of types of intermediate cylinders 41 are arranged for one

shaft member

40A, 40B, a plurality of types of hollow power transmission shafts S can be formed. That is, the

shaft members

40A and 40B have one product number (S001), and the intermediate cylinder 41 has a plurality of product numbers (P001, P002, P003, P004, P005... P (n)). If they are aligned, products of a plurality of types (A001, A002, A003, A004, A005... A (n)) can be formed.

The plural types of intermediate cylinders 41 are those in which the inner and outer diameters are the same as the inner and outer diameters of the cylindrical joint portion 43 of the shaft member 40 (40A, 40B) and the axial lengths are different. That is, since the axial direction length of the drive shaft to be used differs depending on the vehicle, the shaft S having a length corresponding to each vehicle can be manufactured stably.

In the hollow power transmission shaft S of the present invention, the shaft member 40 (40A, 40B) (stem portion) has one specification for one joint size, that is, the shaft member 40 (40A, 40A, 40) at both ends of the intermediate cylindrical body 41. 40B) is a shaft member having the same specifications, and the types of shaft members 40 (40A, 40B) can be integrated. Also. As for the intermediate cylinder 41, it is only necessary to procure one inner and outer diameter for one joint size, and the intermediate cylinder 41 can also be integrated. That is, it is possible to integrate the types of the shaft member 40 (40A, 40B) and the intermediate cylinder 41, thereby improving productivity and reducing costs. Moreover, the load of production management can be reduced by reducing the kind of member. By making the shaft member 40A and the shaft member 40B have the same specifications, it is possible to stably integrate the products.

When the outer diameter of the intermediate cylinder 41 is D and the outer diameter of the shaft member main body 42 is d, D = 0.52 × d + C, and C is 15.92 to 23.09, It can be set as the hollow power transmission shaft S corresponding to the existing (mass produced) hollow power transmission shaft.

As a joining means between the shaft member 40 (40A, 40B) and the intermediate cylinder 41, electron beam welding, laser welding, or friction welding may be used. The joining means can be selected. For this reason, the shaft member and the intermediate cylindrical body can be joined and integrated by an optimum joining means, and the strength is stable.

Also, the shaft member 40 (40A, 40B) can be manufactured by forging or cutting, and is excellent in productivity. Furthermore, the shaft member 40 (40A, 40B) and the intermediate cylinder 41 can be made of a carburized material, a medium carbon steel, an alloy steel, etc., and the material can be selected with a high degree of freedom. The hollow power transmission shaft S can be configured stably.

As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible, and the application (use) is not limited to the drive shaft. Even if it is a propeller shaft, it is not restricted to the drive shaft of a rear-wheel drive vehicle, Furthermore, the front drive shaft of a front-wheel drive vehicle and a 4WD vehicle may be sufficient. In addition to such a power transmission system of an automobile, the present invention can also be used for various general machines, electric machines, transportation machines, and the like having a rotating shaft.

In the drive shaft shown in FIG. 2, the fixed type constant velocity universal joint 1 is a bar field type in the above embodiment, but may be an undercut free type fixed type constant velocity universal joint. The constant velocity universal joint 2 is not limited to the tripod type, but may be a double offset type or a cross groove type sliding type constant velocity universal joint. Further, when the tripod type is used as the sliding type constant velocity universal joint, it may be a single roller type or a double roller type.

It can be used in a power transmission shaft for transmitting power from a differential to a drive wheel in a power transmission system of an automobile. It consists of a pair of shaft members and an intermediate cylinder that is interposed between the pair of shaft members and integrally joined to each shaft member. The shaft member (stem portion) has one specification for one joint size, and the types of shaft members (stem portions) can be integrated. In addition, it is possible to integrate the types of intermediate cylinders.

40, 40A, 40B Shaft member 41 Intermediate cylinder body 42 Main body part 43 Cylindrical joint part 44 Connecting part S Hollow power transmission shaft M Joint part

Claims

A hollow power having a pair of shaft members and an intermediate cylinder that is interposed between the pair of shaft members and integrally joined to each shaft member, and a constant velocity universal joint is connected to an end of each shaft member A transmission shaft,
The pair of shaft members are set to have the same length in the axial direction, and the pair of shaft members have a cylindrical joint having an inner and outer diameter that is the same as the inner and outer dimensions of the intermediate cylinder. Power transmission shaft.
2. The hollow power transmission shaft according to claim 1, wherein the pair of shaft members have the same specification.
The pair of shaft members includes the tubular joint portion, a shaft member main body portion having a smaller diameter than the joint portion, and a connecting portion that is connected to the shaft member main body portion and the joint portion, and is provided outside the intermediate tubular body. 3. The diameter according to claim 1, wherein when the diameter is D and the shaft member main body is d, D = 0.52 × d + C, and C is 15.92 to 23.09. The hollow power transmission shaft as described.
4. The hollow power transmission shaft according to claim 1, wherein the shaft member and the intermediate cylindrical body are joined and integrated by electron beam welding.
The hollow power transmission shaft according to any one of claims 1 to 3, wherein the shaft member and the intermediate cylinder are integrally joined by laser welding.
The hollow power transmission shaft according to any one of claims 1 to 5, wherein the shaft member is a forged product.