JP5459287B2 - Cross shaft type universal joint - Google Patents

Description

  The present invention relates to an improvement of a cross-shaft universal joint (cardan joint) for connecting rotational shafts constituting a steering apparatus for an automobile so that torque can be transmitted. Specifically, even if an excessive torque is applied to this cross joint universal joint due to a collision accident, it is difficult to separate the yoke and the cross shaft, and the fact that the excessive torque was applied is later explained. However, a structure that can be easily determined is realized.

  The vehicle steering apparatus is configured as shown in FIG. 12, and transmits the rotation of the steering wheel 1 to the input shaft 3 of the steering gear unit 2, and a pair of left and right tie rods 4 according to the rotation of the input shaft 3. 4 is pushed and pulled to give a steering angle to the front wheels. The steering wheel 1 is supported and fixed at the rear end portion of the steering shaft 5, and the steering shaft 5 is rotatably supported by the steering column 6 with the cylindrical steering column 6 inserted in the axial direction. Has been. Further, the front end portion of the steering shaft 5 is connected to the rear end portion of the intermediate shaft 8 via a universal joint 7, and the front end portion of the intermediate shaft 8 is connected to the input shaft 3 via another universal joint 9. Connected to. The illustrated example incorporates an electric power steering device that reduces the force required to operate the steering wheel 1 using the electric motor 10 as an auxiliary power source. Therefore, the front end portion of the steering shaft 5 is connected to the input side of the electric power steering device, and the output shaft of the electric power steering device and the rear end portion of the intermediate shaft 8 are connected by the universal joint 7. Torque transmission is connected freely.

  The universal joint 7 connected to the steering shaft 5, the intermediate shaft 8, and the input shaft 3, which are rotating shafts that are incorporated in the above-described steering apparatus for an automobile and do not exist on the same straight line. Reference numeral 9 denotes a cruciform universal joint which is an object of the present invention. Such universal joints have been conventionally known in various structures as described in Patent Documents 1 to 4, for example. FIG. 13 shows an example of a conventional structure described in Patent Document 2 among them.

  The universal joint 11 shown in FIG. 13 is formed by connecting a pair of yokes 12a and 12b via a single cross shaft 13 so that torque can be transmitted. Each of these yokes 12a and 12b is made by pressing or forging a metal material. Each of the yokes 12a and 12b has a base portion 14a and 14b, and a pair of connecting arm portions 15a for each of the yokes 12a and 12b. , 15b. Circular holes 16a and 16b are formed concentrically with respect to the yokes 12a and 12b, respectively, at the ends of the coupling arm portions 15a and 15b. The cross shaft 13 includes four shaft portions 17 and 17 provided such that the central axes of the adjacent shaft portions 17 and 17 are orthogonal to each other. The shafts 17 and 17 are rotatably supported inside the circular holes 16a and 16b via cup-shell radial needle bearings 18 and 18 to form the universal joint 11.

  When a vehicle equipped with a steering device incorporating the universal joints 7, 9, and 11 as described above causes a collision accident or rides on a steered wheel on a curb due to an error in driving operation, from the steering gear unit 2 side. In some cases, shock (excessive) torque is applied to the universal joints 7, 9, and 11. And based on such a shocking torque, all or a part of the constituent members may be damaged, which may hinder continuous safe operation. For example, the coupling arm portions 15a and 15b are distorted, and the concentricity of the circular holes 16a and 16b formed at the distal ends of the coupling arm portions 15a and 15b is impaired. When this concentricity is impaired, the function of each of the radial needle bearings 18 and 18 is impaired, causing problems such as easy wear of each part. In such a case, the user may bring the vehicle into a repair shop and immediately receive inspection and repair. However, some users can continue to use the vehicle without feeling any abnormality. There is sex. Furthermore, when the distortion of the coupling arm portions 15a and 15b is significant, the radial needle bearings 18 and 18 are dropped from the inside of the circular holes 16a and 16b, and the universal joints 7, 9, and 11 There is also a possibility that the torque transmission function is completely lost and the steering device does not function.

JP-A-6-280889 JP-A-8-270669 JP 11-325098 A JP 2009-299706 A

  In the present invention, in view of the circumstances as described above, even when an excessive torque is applied, the connecting arm portion of the yoke is hardly distorted, the torque transmission function is hardly lost, and an excessive torque is applied. It was invented to realize a structure that can easily determine the facts later.

The cruciform universal joint of the present invention includes a pair of yokes and a cruciform shaft that couples the yokes so as to be swingably displaceable.
Of these, the yokes extend in the axial direction from two positions on the diametrically opposite side with respect to the rotating shaft, of the base for coupling and fixing the end of the rotating shaft and one axial end edge of the base. A pair of connecting arm portions that are taken out, and a pair of circular holes that are formed concentrically with each other at the tip ends of both connecting arm portions are provided.
The cross shaft includes four shaft portions provided such that the central axes of adjacent shaft portions are orthogonal to each other.
Furthermore, the tip of the shaft portion of the cross shaft is rotatably supported via bearings inside the circular holes provided in the yokes.

In particular, in the cross shaft type universal joint of the present invention, the phase in the circumferential direction of the peripheral surface of the base portion of at least one of the two yokes matches the both connecting arm portions. By forming a concave groove, which is a long groove in the circumferential direction, in which two circumferential end portions are closed at two circumferential portions, the rigidity in the twist direction of the base portion is extended from the base portion. It is lower than the rigidity in the same direction of the connecting arm portion.
When implementing such a universal joint of the present invention, it is preferable that, as in the invention described in claim 2 , at least the yoke in which the concave groove is formed is made of a metal material by cold forging. It shall be formed by plastic working.

  According to the cruciform universal joint of the present invention configured as described above, even when an excessive torque is applied, the connecting arm portion of the yoke is hardly distorted, and the torque transmission function is hardly lost. That is, since the rigidity in the twisting direction of the base portion of the yoke is lower than the rigidity in the same direction of the pair of connecting arm portions extending from the base portion, both of these are applied when an excessive torque is applied. Before the connecting arm portion is distorted, the base portion is plastically deformed in the twisting direction. For this reason, the magnitude of the torque that leads to the loss or further loss of the torque transmission function can be increased as compared with the conventional structure.

  Further, the fact that an excessive torque is applied can be easily determined later. That is, when the base portion is plastically deformed in the twisting direction, the phase in the rotation direction between the rotating shaft coupled and fixed to the yoke and the both coupling arm portions is shifted. As a result, the attitude of the steering wheel in a neutral state for changing the vehicle straight is changed. This change can be easily and reliably recognized by the driver. For this reason, the driver can be urged to repair, and the danger associated with continuing operation of the damaged vehicle can be avoided. In addition, since the plastic deformation of the base can be easily confirmed at a repair shop, if the driver brings the vehicle to the repair shop, the posture change in the neutral state of the steering wheel is due to the addition of excessive torque. Something can be confirmed easily.

The end view (A) which shows the 1st example of embodiment of this invention, the figure (B) which cut | disconnected through thru | or seen through partly, and was seen from the lower part of (A), and the side view of (B) (C). The same figure (A) as (B) of FIG. 1, sectional drawing (B) of the aa part of (A), and bb part for explaining the sectional shape which is the feature of this example Sectional drawing (C) of FIG. The figure similar to (C) of FIG. 1 which shows the state which applied the excessive torque and the yoke deform | transformed plastically. The figure which shows two other examples of the shape of the ditch | groove of a yoke base. (A) of FIG. 1 (A) similar to FIG. 1 (B) for explaining the effect of the present invention, and (c) of (A) showing a state in which a cross shaft is incorporated for explaining the behavior during torque transmission. The figure corresponding to -c cross section (B), the figure (C) which shows the deformation | transformation state of a pair of coupling arm part which generate | occur | produces in the case of a conventional structure, and the same figure (D) in the case of this invention. The diagram which shows the relationship between the torque which a yoke transmits, and the twist angle of the base which comprises this yoke, and a pair of coupling arm part. The front view which shows the neutral position of a steering wheel with the state (A) before applying shock torque, and the state (B) after applying. A second example of the embodiment of the present invention is shown in a state where a part thereof is seen through or cut off, in a state where it is combined with an intermediate shaft configured to include an outer tube integrated with a yoke and another cross shaft type universal joint. Side view (A) and X arrow view (B) of (A). Similarly, the end surface and sectional drawing which show the 1st example of the manufacturing method of the yoke integral with an outer tube in order of a process. The end view and sectional drawing which show the 2nd example in order of a process. The partially cut side view (A) and the arrow Y view (B) of (A) which show the 3rd example of embodiment of this invention. The partial cutting side view which shows an example of the steering device for motor vehicles incorporating the cross-shaft type universal joint. The disassembled perspective view which shows an example of the conventional structure of a cross-shaft type universal joint.

[First example of embodiment]
A first example of the embodiment of the present invention will be described with reference to FIGS. The feature of the present invention including this example is that the rigidity in the torsional direction of the base of at least one of the pair of yokes constituting the cross joint universal joint is determined from the axial end edge of the base. It is in the point made lower than the rigidity of the same direction of a pair of connecting arm part provided in the state extended in the direction. Since the configuration and operation of the other parts are the same as those of the conventionally known cruciform universal joint including the structure shown in FIG. 13, the overlapping illustrations and explanations are omitted or simplified. Hereinafter, the description will focus on the features of this example.

  The yoke 12c constituting the cross shaft universal joint of this example is formed by subjecting a metal material to a cold forging process, and includes a base portion 14c and a pair of connecting arm portions 15c and 15c. Of these, the base portion 14c is for coupling and fixing the ends of the steering shaft 5 and the intermediate shaft 8 (see FIG. 12), and is formed in a cylindrical shape, and has a spline groove 19 formed on the inner peripheral surface. Yes. The coupling arm portions 15c and 15c extend in the axial direction from two positions on the diametrically opposite side of one end edge in the axial direction of the base portion 14c. In the case of this example, the shape of both the connecting arm portions 15c, 15c is a flat plate shape, and concentric circular holes 16c, 16c are formed at respective tip portions.

  Further, in the case of the yoke 12c constituting the cross shaft type universal joint of the present example, in the circumferential surface of the base portion 14c, the phase in the circumferential direction coincides with the both connecting arm portions 15c and 15c, respectively. Concave grooves 20 and 20 are formed. Both the concave grooves 20 and 20 are long grooves in the circumferential direction, each of which is closed at both ends in the circumferential direction. The shape of both the concave grooves 20 and 20 may be a long rectangle as shown in FIG. 1C, or a shape having a circular portion in the middle as shown in FIG. An elliptical shape as shown in FIG. In any case, by forming the both concave grooves 20, 20, the rigidity of the base portion 14c in the twisting direction is made lower than the rigidity of the connecting arm portions 15c, 15c in the same direction. The dimensions (depth, circumferential length, width) and shape (opening shape, cross-sectional shape), and number (two in the illustrated example) of the both concave grooves 20, 20 are normal (excessive). Ensuring sufficient rigidity (in a state before the torque is applied) (in a state where the torque can be transmitted without deformation of the base portion 14c), and the above-described condition ("torsional rigidity of the base portion 14c" <"double coupling Designed by experiment or computer analysis so as to satisfy the torsional rigidity of the arm portions 15c, 15c ").

  According to the cruciform universal joint of the present example incorporating the yoke 12c as described above, both the connecting arm portions 15c and 15c constituting the yoke 12c are hardly distorted even when an excessive torque is applied. The torque transmission function can be made difficult to lose. That is, based on the presence of the concave grooves 20, 20, the rigidity of the base portion 14c in the twisting direction is made lower than the rigidity of the connecting arm portions 15c, 15c extending from the base portion 14c in the same direction. Therefore, when an excessive torque is applied to the yoke 12c, the base portion 14c is plastically deformed in the twisting direction before the connecting arm portions 15c and 15c are distorted. In this case, both the connecting arm portions 15c and 15c are not plastically deformed and are maintained in a shape as they are.

  That is, an impact excessive torque may be applied to the cruciform universal joint incorporating the yoke 12c and the cruciform shaft 13 due to a collision accident or a curb ride on the steering wheel. In such a case, a pair of connecting arm portions 15c and 15c constituting the yoke 12c are shown in FIG. 5B from both ends of any shaft portion 17 constituting the cross shaft 13. A large load is applied to the four α portions. When the torsional rigidity of both the connecting arm portions 15c and 15c is low (“torsional rigidity of the base portion 14c”> “torsional rigidity of both the connecting arm portions 15c and 15c”), based on the excessive torque, FIG. As shown in (C), the concentricity of the circular holes 16c, 16c formed at the distal ends of the coupling arm portions 15c, 15c is impaired, and the radial needle bearing 18 is placed inside the circular holes 16c, 16c. When the shaft portion 17 supported by the shaft 18 is not smoothly displaced, or when the shaft portion 17 is remarkably moved, the radial needle bearings 18 and 18 may come out of the circular holes 16c and 16c. As a result, the function of the steering apparatus for an automobile incorporating the cross shaft type universal joint is reduced or lost.

  On the other hand, in the case of the structure of this example, as described above, the torsional rigidity of the base part 14c is lower than the torsional rigidity of both the connecting arm parts 15c, 15c. As shown in FIG. 3, the base portion 14c is plastically deformed in the twisting direction. The plastic deformation of both the connecting arm portions 15c and 15c based on the excessive torque does not occur or even slightly occurs even when it occurs. Therefore, as shown in FIG. 5D, the shape of the both connecting arm portions 15c, 15c is maintained almost as it is, and the circular holes formed at the tip portions of the both connecting arm portions 15c, 15c. The concentricity of 16c and 16c is maintained. For this reason, the state where the rocking displacement of the shaft portion 17 is smoothly performed is maintained. Of course, the radial needle bearings 18 and 18 do not come out of the circular holes 16c and 16c. As a result, the function of the steering apparatus for automobiles incorporating the cross shaft type universal joint is maintained almost as it is.

  In short, according to the structure of the present example, the torque transmission function of the cross shaft universal joint is impaired or further lost, and the magnitude of the torque that can be lost can be increased as compared with the conventional structure. This point will be described with reference to FIG. FIG. 6 shows the torsion angle with respect to the neutral position, which exists between the rotary shaft coupled to the yoke and the cross shaft on the horizontal axis, and the yoke that exists between the rotary shaft and the cross shaft on the vertical axis. The magnitude of the torque applied to each is shown. When this torque increases, the yoke begins to plastically deform at point i, but between the line B and line C, the base portion 14c mainly undergoes plastic deformation in the twisting direction, and both the connecting arm portions 15c and 15c are almost completely deformed. Does not plastically deform. At two points, as shown in FIG. 5C, the radial needle bearings 18 and 18 come out of the circular holes 16c and 16c, and the cross shaft universal joint is destroyed. The transmission function is lost.

  In the case of the structure of this example, during the period from line B to line C, the base portion 14c is plastically deformed to absorb excessive torque energy (impact energy) applied to the cruciform universal joint impactively. To do. The amount of energy absorbed by the plastic deformation of the base portion 14c is proportional to the area of the lower portion of the curve showing the relationship between the torque and the torsion angle shown by the oblique lattice in FIG. Therefore, as apparent from FIG. 6, according to the structure of the present invention, the impact energy absorption performance can be increased, and parts other than the cross shaft type universal joint incorporating the yoke 12c can be obtained based on the excessive torque. Easy to prevent damage. In order to increase the impact energy absorbing performance, a concave groove is formed in the base portion of any of the pair of yokes constituting the cross shaft universal joint. Further, for example, if a concave groove is formed in the base portion of any one of the four yokes constituting a pair of cross shaft universal joints provided at both ends of the intermediate shaft, the impact energy absorbing performance can be obtained. Can be increased.

  Further, the fact that an excessive torque is applied can be easily determined later. That is, when the base portion 14c is plastically deformed in the twisting direction, the phase in the rotational direction between the rotating shaft coupled and fixed to the yoke 12c and the coupling arm portions 15c and 15c is shifted. As a result, the neutral posture of the steering wheel 1 for changing the vehicle straight is changed. That is, in a state before the yoke 12c is plastically deformed, when the vehicle is in a straight traveling state, the posture of the steering wheel 1 is maintained at the initial state shown in FIG. On the other hand, a shocking torque is applied to the yoke 12c by the impact energy, and the base portion 14c of the yoke 12c is plastically deformed in the twisting direction, and the rotation direction of the base portion 14c and the both connecting arm portions 15c and 15c. When the phase is shifted, the neutral posture of the steering wheel 1 for making the vehicle go straight is changed as shown in the order of (A) → (B) in FIG. 7, for example. This change can be easily and reliably recognized by the driver. For this reason, the driver can be urged to repair, and the danger associated with continuing the operation of the damaged vehicle can be avoided. Further, since the plastic deformation of the base portion 14c can be easily confirmed at a repair shop, if the driver brings the vehicle into the repair shop, the posture change in the neutral state of the steering wheel 1 is due to the addition of excessive torque. It can be easily confirmed that it is.

[Second Example of Embodiment]
8 to 10 show a second example of the embodiment of the present invention. The present invention shows a case where the present invention is applied to a so-called tube yoke in which the outer shaft 21 constituting the intermediate shaft 8a and the yoke 12d constituting the universal joint 9a are integrated. Such a tube yoke is made of carbon steel such as S10C to S45C, as is conventionally known, and is extruded into a cylindrical material 22 as shown in FIG. Are sequentially subjected to cold forging, etc., and after passing through a first intermediate material 23 as shown in FIG. 9B and a second intermediate material 24 as shown in FIG. The yoke 12d is formed by integrating the outer shaft 21. Then, the protruding portion 26 of the pressing die 25 is pressed against the outer peripheral surface of the base portion 14d of the yoke 12d, and the portion is plastically deformed to form concave grooves 20a and 20a. In addition, as shown in FIG. 10A, the forming operation of the both concave grooves 20a, 20a is performed by changing the portion to be the pair of connecting arm portions 15d, 15d at the tip of the intermediate material with the outer shaft 21. It can also be performed in a state where the portion to be formed is bent at a right angle outward in the radial direction. Both the connecting arm portions 15d and 15d are bent until they are parallel to the central axis of the outer shaft 21 after the both concave grooves 20a and 20a are formed.

In any case, it is preferable to form the both concave grooves 20a and 20a, and then perform heat treatment such as soft nitriding to make the surface hard and the core soft. This is because the surface is hardened to ensure durability, and when excessive torque is applied, the portion of the base portion 14d where the concave grooves 20a and 20a are formed is reliably plastic in the twisting direction. This is to make it deform. Further, the outer shaft 21 and the inner shaft 27 are combined so as to expand and contract via a ball spline 28 to form the intermediate shaft 8a. Further, another universal joint 7 a is assembled to the end of the inner shaft 27. The structure and operation of the intermediate shaft 8a have been widely known in the past, and the other universal joint 7a has also been widely known. Further, none of them is related to the gist of the present invention, and thus detailed description is omitted.
In addition, regarding the structure and operation of the universal joint 9a to which the present invention is applied, the double groove 20a, 20a, which is a characteristic part of the present invention, is the case of the first example of the embodiment described above. Since it is the same, the overlapping description is omitted.

[Third example of embodiment]
FIG. 11 shows a third example of the embodiment of the present invention. In the case of the universal joint 7b of this example, the yoke 12e made by cold forging and the end of the intermediate shaft 8b are joined and fixed by welding. Since the pair of concave grooves 20a, 20a, which is a characteristic part of the present invention, is the same as in the case of the first example of the embodiment described above, a duplicate description is omitted.

When practicing the present invention, the method for forming the groove is not particularly limited. As shown in the drawing, it can be formed by cutting or the like in addition to the method of forming by pressing the protrusion of the pressing die and plastically deforming it.
In addition, the position where the concave groove is formed is a portion that is disengaged from the pair of coupled arm portions, and can be plastically deformed in the twisting direction by excessive torque, and the occurrence of large damage to the extent that the function such as tearing is lost. For example, it can be set in the L range of FIG.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering gear unit 3 Input shaft 4 Tie rod 5 Steering shaft 6 Steering column 7, 7a, 7b Universal joint 8, 8a, 8b Intermediate shaft 9, 9a Universal joint 10 Electric motor 11 Universal joint 12a, 12b, 12c, 12d , 12e Yoke 13 Cross shaft 14a, 14b, 14c, 14d Base 15a, 15b, 15c, 15d Joint arm 16a, 16b, 16c Circular hole 17 Shaft 18 Radial needle bearing 19 Spline groove 20, 20a Concave groove 21 Outer shaft 22 Material 23 First intermediate material 24 Second intermediate material 25 Stamping die 26 Projection 27 Inner shaft 28 Ball spline

Claims (2)

A pair of yokes, and a cross shaft that couples the yokes in a swingable manner,
Each of these yokes extends in the axial direction from two positions on the opposite side in the diametrical direction with respect to the rotating shaft, of the base for coupling and fixing the end of the rotating shaft and one axial end edge of the base. A pair of coupled arm portions, and a pair of circular holes formed concentrically with each other at the distal ends of the coupled arm portions;
The cross shaft is provided with four shaft portions provided in a state where the central axes of adjacent shaft portions are orthogonal to each other,
In the cross shaft type universal joint in which the tip end portions of the shaft portions of the cross shaft are rotatably supported through bearings inside the circular holes provided in the two yokes, respectively.
Of the circumferential surfaces of the base portion of at least one of the two yokes , the circumferential direction phase coincides with the two connecting arm portions, and two circumferential portions of the base portion are closed at both circumferential ends. By forming a concave groove that is a long groove that is long in the circumferential direction, the rigidity in the twisting direction of the base portion is made lower than the rigidity in the same direction of the pair of connecting arm portions extending from the base portion. A cross joint universal joint characterized by 2. The cross shaft type universal joint according to claim 1, wherein at least the yoke formed with the two concave grooves is formed by subjecting a metal material to plastic working by cold forging. 3.

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