JP2013256972A - Cross-type universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a structure, which hardly causes distortion of coupling arm parts 15c, 15c of a yoke 12c and the loss of a torque transmitting function even when an excessive torque is applied, and which facilitates the determination of a fact that the excessive torque is applied even afterwards.SOLUTION: With respect to the rigidity in a twisting direction of a base portion 14c of a yoke 12c, recessed grooves 20, 20 are formed in the base portion 14c, whereby the twisting rigidity of a connecting arm portion 15c provided with the recessed grooves 20, 20 is made lower than the twisting rigidity of a connecting arm portion 15c free from the recessed grooves 20, 20. Since the base portion 14c is plastically deformed in the twisting direction, when an excessive torque is applied, to suppress the deformation of both the connecting arm portions 15c, 15c, the above problem can be solved.

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. More specifically, when an excessive torque is applied to the cruciform universal joint due to a collision accident or the like, a structure in which the fact that the excessive torque is applied can be easily determined later is realized.

  The vehicle steering system is configured as shown in FIG. 1 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 as the input shaft 3 rotates. 4 is pushed and pulled to give a steering angle to the front wheels. The steering wheel 1 is supported and fixed to 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 are conventionally known in various structures, as described in Patent Documents 1 and 2, for example. FIG. 6 shows an example of a conventional structure described in Patent Document 2 among them.

  The universal joint 11 shown in FIG. 6 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 shaft portions 17 and 17 are rotatably supported inside the circular holes 16a and 16b via cup shell type 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, even if the user brings the vehicle into a repair shop, an inexperienced worker may not find the abnormality of the universal joints 7, 9, and 11 depending on the degree of damage.

Japanese Utility Model Publication No. 52-053878 JP-A-8-270669

In view of the circumstances as described above, the present invention has been invented to realize a structure that can easily determine the fact that an excessive torque has been applied to a universal joint due to a collision accident or an error in driving operation.

  In order to achieve this object, the present invention includes a pair of yokes and a cross shaft that couples the two yokes so as to be swingably displaceable. A base part for coupling and fixing, a pair of coupling arm parts extending in the axial direction from two positions on the opposite side in the diametrical direction with respect to the rotation axis, of one end edge in the axial direction of the base part, and both the coupling arm parts A pair of circular holes formed concentrically with each other, and the cross shaft is provided with four shaft portions provided such that the central axes of adjacent shaft portions are orthogonal to each other. A cross-shaft universal joint in which the tip of the shaft portion of the cross shaft is rotatably supported via bearings inside the circular holes provided in the yokes, respectively. However, only one arm of the opposing arm of the both connecting arm portions is provided with both corners. Features a cross-shaft universal joint characterized in that the rigidity in the twisting direction of the base is made lower than the rigidity in the same direction of the other coupling arm by providing two concave grooves in the root To do.

  In particular, in the cross shaft type universal joint of the present invention, by forming concave grooves at both corners of the base of one of the coupled arm portions, the rigidity in the twisting direction of the base portion, It is lower than the rigidity of the other connecting arm portion in the same direction.

  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 one connecting arm part of this yoke is lower than the rigidity in the same direction of the other connecting arm part, both of these connecting arm parts are applied when an excessive torque is applied. The base portion is plastically deformed in the twisting direction before the cross shaft coupled through the radial needle bearing is distorted. 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 partial cutting side view which shows an example of the steering device incorporating the cross-shaft type universal joint. The side view combined with the intermediate shaft and other cross-axis type universal joint which comprised embodiment of this invention. The top view (A) which shows the Example of this invention, the figure (B) seen from the lower part of (A) which cut | disconnected or seen through partly, and the figure (C) seen from the side of (B) . FIG. 3 is a state diagram in which an excessive torque is applied and the yoke is plastically deformed. 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. The disassembled perspective view which shows an example of the conventional structure of a cross-shaft type universal joint.

  2 to 3 show an embodiment of the present invention. The feature of the present invention including this example is that a groove is provided at one base of a pair of connecting arm portions constituting one yoke of a pair of yokes constituting a cross shaft universal joint. It is in. 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. 6, 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. In the case of the structure of this example, the base portion 14c and the circular outer shaft 19 are integrally formed. In other words, the base portion 14c is integrally provided at the axial end portion (upper side in FIG. 3) of the outer shaft 19. The base portion 14c has a cylindrical shape, and the coupling arm portions 15c and 15c are respectively connected to the outer portion of the base portion 14c from two positions opposite to the outer shaft 19 on the diametrically opposite side. It extends in the axial direction toward the opposite side of the shaft 19. 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. The outer shaft 19 constitutes an intermediate shaft 8 (see FIG. 1) that can be expanded and contracted by ball spline engagement (including general spline engagement) by an inner shaft 27 and a ball 28 as shown in FIG. To do. Regarding this point, since it is a conventionally well-known structure, detailed illustration and description are omitted.

  In the case of the yoke 12c constituting the cross shaft type universal joint of this example, the concave grooves 20, 20 are formed at both corners of the base of the connecting arm portion 15c of the one base portion 14c of the both connecting arm portions 15c, 15c. ing. By forming the concave grooves 20 and 20, the rigidity of the base portion 14c in the twisting direction is made lower than the rigidity of the other connecting arm portion 15c where the concave grooves 20 and 20 are not provided. The dimensions (depth, circumferential length, width) and shape (opening shape, cross-sectional shape) of the concave grooves 20 and 20 have sufficient rigidity at a normal time (before an excessive torque is applied). (Where the base portion 14c is capable of transmitting torque without being deformed), and the above-described conditions ("torsional rigidity of the coupling arm portion 15c with the concave grooves 20, 20" <"the concave grooves 20, 20 It is determined by design by experiment or computer analysis so as to satisfy the torsional rigidity of the unconnected arm portion 15c.

  According to the cruciform universal joint of this example incorporating the yoke 12c as described above, even when an excessive torque is applied, the connecting arm portion 15c constituting the yoke 12c is not easily distorted, and torque transmission is performed. It is difficult to lose function. That is, based on the presence of the concave grooves 20, 20, the torsional rigidity of the coupling arm portion 15c with the concave grooves 20, 20 is made lower than the torsional rigidity of the coupling arm portion 15c without the concave grooves 20, 20, When an excessive torque is applied to the yoke 12c, the base portion 14c having the concave grooves 20 and 20 is formed before the coupling arm portions 15c and 15c, the cross shaft 13, and the radial needle bearings 18 and 18 are distorted. Plastic deformation in the twist direction. 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 large load is applied to the pair of connecting arm portions 15c, 15c constituting the yoke 12c from both end portions of any shaft portion 17 constituting the cross shaft 13. When the torsional rigidity of both the connecting arm portions 15c, 15c is high, the concentricity of the circular holes 16c, 16c formed at the distal ends of the both connecting arm portions 15c, 15c is impaired based on the excessive torque, If the shaft portion 17 supported by the radial needle bearings 18 and 18 is not smoothly displaced inside the circular holes 16c and 16c, or if it is remarkable, both the radial needle bearings 18 and 18 are used. May escape from both the circular holes 16c, 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 connecting arm portion 15c having the recessed grooves 20 and 20 is set to be higher than the torsional rigidity of the connecting arm portion 15c having no recessed grooves 20 and 20. Therefore, the base portion 14c is first plastically deformed in the twist direction as shown in FIG. 4 due to the excessive torque. 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. 4, the shape of both the connecting arm portions 15c and 15c is maintained almost as it is, and the circular holes 16c and 16c formed at the tip portions of the both connecting arm portions 15c and 15c are maintained. Concentricity 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. For example, if a concave groove is formed in the base of any of the four yokes, each of which constitutes a pair of cruciform universal joints provided at both ends of the intermediate shaft, The impact energy absorption performance 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, for example, as shown in the order of (A) → (B) in FIG. 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.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering gear unit 3 Input shaft 4 Tie rod 5 Steering shaft 6 Steering column 7 Universal joint 8 Intermediate shaft 9 Universal joint 10 Electric motor 11 Universal joint 12a, 12b, 12c, 12d, 12e Yoke
13 Cross shafts 14a, 14b, 14c, 14d Base portions 15a, 15b, 15c, 15d Joint arm portions 16a, 16b, 16c Circular hole 17 Shaft portion 18 Radial needle bearing 19 Spline groove 20 Concave groove 21 Outer shaft 27 Inner shaft 28 Ball

Claims (1)

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 both 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.
By providing concave grooves at two corners of only one arm of the opposing arm of both the connecting arm portions, the rigidity in the twisting direction of the base portion is higher than the rigidity in the same direction of the other connecting arm portion. A cross-shaft universal joint characterized by being lowered.

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