JP2019199892A - Buffer joint and steering device - Google Patents

Abstract

To provide a buffer joint having high buffering performance, in which a shaft and a bush can be easily connected to each other.SOLUTION: The buffer joint comprises a shaft, a bush, a housing, and a stopper. The bush comprises: a cylindrical inner ring fitted to an outside of the shaft; a cylindrical outer ring positioned outside the inner ring; and an elastic body positioned between the inner ring and the outer ring. The housing is fitted to an outside of the outer ring. The stopper is penetrated through the shaft, the bush and the housing. The shaft comprises: a first large diameter portion and a second large diameter portion each in contact with the inner ring; and a small diameter portion positioned between the first large diameter portion and the second large diameter portion, and having an outer diameter smaller than an inner diameter of the inner ring.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a buffer joint and a steering device.

  A vehicle is provided with a steering device as a device for transmitting an operation of an operator (driver) to a steering wheel to the wheel. In order to prevent vibration transmitted from the road surface or the like to the steering device from being transmitted to the steering wheel, a buffer joint may be used in the steering device. An example of the buffer joint is an elastic shaft joint described in Patent Document 1. The elastic shaft coupling of Patent Document 1 includes an elastic member between the shaft and the housing. The elastic member includes a circular outer ring and an inner tube, and a cylindrical elastic body disposed between the appearance and the inner tube.

No. 7-43494

  In order to improve the buffering performance of the buffer joint, it is desirable to increase the axial length of the bush (the elastic member referred to in Patent Document 1). On the other hand, the shaft and the bush are connected by press fitting. The longer the bush is in the axial direction, the greater the required pressure input, and the more likely the change in the inner diameter of the bush (change in tightening allowance between the shaft and the bush) occurs. As a result, the variation in press-fit load tends to increase. For this reason, it is difficult to appropriately connect the shaft and the bush.

  This indication is made in view of said subject, Comprising: It aims at providing the buffer joint which has high buffer performance and can connect a shaft and a bush easily.

  In order to achieve the above object, a shock-absorbing joint according to one aspect of the present disclosure includes a shaft, a cylindrical inner ring that fits outside the shaft, a cylindrical outer ring that is located outside the inner ring, and A bush provided with an elastic body positioned between the inner ring and the outer ring, a housing that fits outside the outer ring, a shaft, the bush, and a stopper that penetrates the housing, The shaft is positioned between the first large diameter portion and the second large diameter portion in contact with the inner ring, and between the first large diameter portion and the second large diameter portion and is smaller than the inner diameter of the inner ring. A small-diameter portion having a diameter.

  By providing the shaft with the small diameter portion, the effective press-fitting length when the shaft and the bush are connected by press-fitting is reduced. For this reason, even when the bush is lengthened in the axial direction in order to enhance the buffer performance, the change in the inner diameter of the bush (change in the tightening allowance between the shaft and the bush) is suppressed. For this reason, variations in the press-fit load are suppressed. Therefore, the buffer joint has a high buffer performance and can easily connect the shaft and the bush.

  As a desirable mode of the buffer joint, the length of the bush in the axial direction of the shaft is larger than the outer diameter of the bush.

  Thereby, the buffer joint is reduced in size, and the buffer performance of the buffer joint is improved.

  As a desirable mode of the buffer joint, the lengths of the inner ring, the outer ring, and the elastic body in the axial direction of the shaft are not less than the length of the small diameter portion in the axial direction.

  This increases the torsional rigidity of the bush. The shock-absorbing joint can achieve both a reduction in effective press-fitting length when the shaft and the bush are connected by press-fitting and a strong connection between the shaft and the bush.

  As a desirable mode of the buffer joint, the stopper penetrates the first large diameter portion or the second large diameter portion.

  Thereby, compared with the case where a stopper penetrates a small diameter part, the maximum load which can be transmitted between a shaft and a stopper becomes large. Further, the fatigue strength of the shaft is improved.

  As a desirable mode of the buffer joint, the stopper penetrates the first large diameter portion. The length of the first large diameter portion in the axial direction of the shaft is larger than the minimum diameter of the stopper.

  Thereby, the defect | deletion of the part adjacent to a 1st large diameter part at the time of drilling etc. to a 1st large diameter part is suppressed. For this reason, it is easy to form a hole for inserting the stopper.

  As a desirable mode of the buffer joint, the first large diameter portion is located on an end side of the shaft that overlaps the housing with respect to the small diameter portion, and the shaft includes the small diameter portion and the second large diameter portion. A tapered portion having an outer diameter that increases toward the second large-diameter portion is provided between the diametric portion and the diametric portion.

  Thereby, when the shaft and the bush are connected by press-fitting, the shaft is hardly caught on the inner peripheral surface of the inner ring. Therefore, the assembly of the shaft and the bush becomes easy.

  As a desirable aspect of the buffer joint, the first large diameter portion is located on an end portion side of the shaft that overlaps the housing with respect to the small diameter portion, and the first large diameter portion is on the small diameter portion side. And an end face orthogonal to the axial direction of the shaft.

  Thereby, the edge of the first large-diameter portion on the small-diameter portion side is easily caught on the inner peripheral surface of the inner ring. That is, the edge on the small diameter portion side of the first large diameter portion functions as a so-called return. For this reason, it is suppressed that a bush comes off from a shaft.

  In order to achieve the above object, a shock-absorbing joint according to one aspect of the present disclosure includes a shaft, a cylindrical inner ring that fits outside the shaft, a cylindrical outer ring that is located outside the inner ring, and A bush provided with an elastic body positioned between the inner ring and the outer ring, a housing that fits outside the outer ring, a shaft, the bush, and a stopper that penetrates the housing, The bush has a first small diameter portion and a second small diameter portion in contact with the shaft, and a large diameter portion located between the first small diameter portion and the second small diameter portion and having an inner diameter larger than the outer diameter of the shaft. And comprising.

  Thereby, the effective press-fitting length when the shaft and the bush are connected by press-fitting is reduced. For this reason, even when the bush is lengthened in the axial direction in order to enhance the buffer performance, the change in the inner diameter of the bush (change in the tightening allowance between the shaft and the bush) is suppressed. For this reason, variations in the press-fit load are suppressed. Therefore, the buffer joint has a high buffer performance and can easily connect the shaft and the bush.

  In order to achieve the above object, a steering device according to an aspect of the present disclosure includes the above-described cushion joint. Thereby, the steering device can suppress transmission of vibration to the steering wheel and can be easily assembled.

  According to the present disclosure, it is possible to provide a buffer joint that has high buffer performance and can easily connect the shaft and the bush.

FIG. 1 is a schematic diagram of a steering apparatus according to the present embodiment. FIG. 2 is a perspective view of the steering apparatus of the present embodiment. FIG. 3 is a cross-sectional view of the buffer joint of the present embodiment. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a side view of the shaft of the present embodiment. FIG. 7 is a side view of the bush of the present embodiment. FIG. 8 is a cross-sectional view of a buffer joint according to a modification.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the following modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

(Embodiment)
FIG. 1 is a schematic diagram of a steering apparatus according to the present embodiment. FIG. 2 is a perspective view of the steering apparatus of the present embodiment. As shown in FIG. 1, the steering device 80 includes a steering wheel 81, a steering shaft 82, a steering force assist mechanism 83, a first universal joint 84, and an intermediate shaft 85 in the order in which the force given by the operator is transmitted. And a second universal joint 86, which are joined to the pinion shaft 87. In the following description, the front in the vehicle on which the steering device 80 is mounted is simply described as the front, and the rear in the vehicle is simply described as the rear.

  As shown in FIG. 1, the steering shaft 82 includes an input shaft 82a and an output shaft 82b. One end of the input shaft 82a is connected to the steering wheel 81, and the other end of the input shaft 82a is connected to the output shaft 82b. One end of the output shaft 82 b is connected to the input shaft 82 a, and the other end of the output shaft 82 b is connected to the first universal joint 84.

  As shown in FIG. 1, the intermediate shaft 85 connects the first universal joint 84 and the second universal joint 86. As shown in FIG. 2, an upper shaft 85a and a lower shaft 85b are provided. The upper shaft 85a is a substantially cylindrical member. The lower shaft 85b is a substantially cylindrical member. A part of the lower shaft 85b is inserted into the upper shaft 85a. The serration provided on the inner peripheral surface of the upper shaft 85a meshes with the serration provided on the outer peripheral surface of the lower shaft 85b. The upper shaft 85a and the lower shaft 85b do not move relatively at the normal time, but absorb the shock by moving relatively at the time of a vehicle collision.

  The end of the upper shaft 85 a is connected to the first universal joint 84. The end of the lower shaft 85 b is connected to the second universal joint 86. One end of the pinion shaft 87 is connected to the second universal joint 86. The other end of the pinion shaft 87 is connected to the steering gear 88. The first universal joint 84 and the second universal joint 86 are, for example, cardan joints. The rotation of the steering shaft 82 is transmitted to the pinion shaft 87 via the intermediate shaft 85. That is, the intermediate shaft 85 rotates with the steering shaft 82.

  As shown in FIG. 1, the steering gear 88 includes a pinion 88a and a rack 88b. The pinion 88a is connected to the pinion shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 converts the rotational motion transmitted to the pinion 88a into a linear motion by the rack 88b. The rack 88 b is connected to the tie rod 89. The angle of the wheels changes as the rack 88b moves.

  As shown in FIG. 1, the steering force assist mechanism 83 includes a speed reducer 92 and an electric motor 93. The speed reducer 92 is, for example, a worm speed reducer. Torque generated by the electric motor 93 is transmitted to the worm wheel via the worm inside the speed reducer 92 and rotates the worm wheel. The reduction gear 92 increases the torque generated by the electric motor 93 by the worm and the worm wheel. The speed reducer 92 gives auxiliary steering torque to the output shaft 82b. That is, the steering device 80 is a column assist system.

  As shown in FIG. 1, the steering device 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 94, and a vehicle speed sensor 95. The electric motor 93, the torque sensor 94, and the vehicle speed sensor 95 are electrically connected to the ECU 90. The torque sensor 94 outputs the steering torque transmitted to the input shaft 82a to the ECU 90 by CAN (Controller Area Network) communication. The vehicle speed sensor 95 detects the traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The vehicle speed sensor 95 is provided in the vehicle body and outputs the vehicle speed to the ECU 90 by CAN communication.

  The ECU 90 controls the operation of the electric motor 93. The ECU 90 acquires signals from each of the torque sensor 94 and the vehicle speed sensor 95. The ECU 90 is supplied with electric power from a power supply device 99 (for example, an in-vehicle battery) in a state where the ignition switch 98 is on. The ECU 90 calculates an auxiliary steering command value based on the steering torque and the vehicle speed. The ECU 90 adjusts the power value supplied to the electric motor 93 based on the auxiliary steering command value. The ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided in the electric motor 93. As the ECU 90 controls the electric motor 93, the force required to operate the steering wheel 81 is reduced.

  FIG. 3 is a cross-sectional view of the buffer joint of the present embodiment. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a side view of the shaft of the present embodiment. FIG. 7 is a side view of the bush of the present embodiment.

  As shown in FIG. 2, the buffer joint 1 in the present embodiment connects the first universal joint 84 and the upper shaft 85 a of the intermediate shaft 85.

  The buffer joint 1 is a device for connecting two members and absorbing vibration transmitted from the road surface or the like to the steering device 80. When the buffer joint 1 absorbs vibration, vibration transmitted to the steering wheel 81 is reduced. As shown in FIG. 3, the buffer joint 1 includes a shaft 2, a bush 3, a housing 4, and a stopper 6.

  As shown in FIG. 3, the shaft 2 in the present embodiment is an end portion of the upper shaft 85a. The shaft 2 includes a first large diameter portion 21, a second large diameter portion 22, a first taper portion 24, a small diameter portion 25, and a second taper portion 26.

  In the following description, the axial direction of the shaft 2 is simply referred to as the axial direction. The direction orthogonal to the axial direction is described as the radial direction. A direction along a circle around the rotation axis of the shaft 2 is described as a circumferential direction.

  As shown in FIG. 3, the first large-diameter portion 21 is located on the end portion side that overlaps the housing 4 of the shaft 2 with respect to the small-diameter portion 25. In the following, the end of the shaft 2 that overlaps the housing 4 is simply referred to as the end of the shaft 2. As shown in FIG. 6, the outer diameter D21 of the first large diameter portion 21 is constant. The first large diameter portion 21 is adjacent to the small diameter portion 25. As shown in FIG. 6, the first large diameter portion 21 includes an end face 21 a on the small diameter portion 25 side. The end surface 21a is orthogonal to the axial direction. That is, the portion of the shaft 2 between the first large diameter portion 21 and the small diameter portion 25 is not chamfered.

  As shown in FIG. 3, the second large diameter portion 22 is located on the opposite side of the housing 4 with respect to the small diameter portion 25. As shown in FIG. 6, the outer diameter D22 of the second large diameter portion 22 is constant. The outer diameter D22 of the second large diameter portion 22 is equal to the outer diameter D21 of the first large diameter portion 21.

  The first taper portion 24 is located at the end of the shaft 2. The first tapered portion 24 is adjacent to the first large diameter portion 21. The outer diameter of the first taper portion 24 decreases toward the tip side (the side opposite to the first large diameter portion 21). For example, the first tapered portion 24 is formed by chamfering the tip portion of the shaft 2. The first tapered portion 24 makes it difficult for the tip of the shaft 2 to be caught by the inner ring 31 when the shaft 2 and the bush 3 are connected by press fitting. Therefore, the assembly of the shaft 2 and the bush 3 is facilitated.

  As shown in FIG. 6, the small diameter portion 25 is located between the first large diameter portion 21 and the second large diameter portion 22. The outer diameter D25 of the small diameter portion 25 is smaller than the outer diameter D21 of the first large diameter portion 21. The second taper portion 26 is located between the small diameter portion 25 and the second large diameter portion 22. The second tapered portion 26 is adjacent to the small diameter portion 25 and the second large diameter portion 22. The outer diameter of the second taper portion 26 decreases toward the small diameter portion 25. For example, the second tapered portion 26 is formed by chamfering a portion between the second large diameter portion 22 and the small diameter portion 25 in the shaft 2.

  As shown in FIG. 3, the bush 3 is a cylindrical member and is disposed outside the shaft 2. The bush 3 is a buffer material that absorbs vibration. As shown in FIG. 7, the length L3 of the bush 3 in the axial direction is larger than the outer diameter D3 of the bush 3. The length L3 of the bush 3 is preferably not less than 2 times and not more than 4 times the length L25 of the small diameter portion 25 in the axial direction shown in FIG. That is, it is desirable that the length L25 of the small diameter portion 25 is ¼ or more and ½ or less of the length L3 of the bush 3. As shown in FIG. 3, the bush 3 includes an inner ring 31, an outer ring 33, and an elastic body 32.

  The inner ring 31 is a cylindrical member that fits outside the shaft 2. The inner ring 31 is press-fitted outside the shaft 2. The inner ring 31 is in contact with the first large diameter portion 21 and the second large diameter portion 22. An inner diameter D31 of the inner ring 31 shown in FIG. 7 is larger than an outer diameter D25 of the small diameter portion 25 shown in FIG. As shown in FIG. 3, there is a gap 20 between the inner ring 31 and the small diameter portion 25. The gap 20 is annular. The position of the end face of the inner ring 31 in the axial direction is equal to the position of the end face of the first large diameter portion 21 in the axial direction.

  The outer ring 33 is a cylindrical member located outside the inner ring 31. The position of the end face of the outer ring 33 in the axial direction is equal to the position of the end face of the first large diameter portion 21 in the axial direction. The length of the outer ring 33 in the axial direction is equal to the length of the inner ring 31 in the axial direction. The length L3 of the bush 3 described above means the length of the outer ring 33 in the axial direction and the length of the inner ring 31 in the axial direction.

  The elastic body 32 is a cylindrical member located between the inner ring 31 and the outer ring 33. The elastic body 32 is made of, for example, synthetic rubber. The elastic body 32 absorbs vibration transmitted to the shaft 2. The inner peripheral surface of the elastic body 32 is in contact with the outer peripheral surface of the inner ring 31. The outer peripheral surface of the elastic body 32 is in contact with the inner peripheral surface of the outer ring 33. When the inner ring 31 and the outer ring 33 are relatively rotated or moved in the axial direction, the elastic body 32 is deformed.

  The length L3 of the bush 3 (the length of the inner ring 31 and the length of the outer ring 33) and the length L4 of the elastic body 32 are not less than the length L25 of the small diameter portion 25 in the axial direction. For this reason, the inner ring 31, the outer ring 33, and the elastic body 32 are disposed so as to straddle the small diameter portion 25 (arranged from the first large diameter portion 21 to the second large diameter portion 22). Thereby, the torsional rigidity of the bush 3 is increased. Further, the length L4 of the elastic body 32 in the axial direction is larger than the outer diameter D3 of the bush 3. Thereby, the difference between the length L3 of the bush 3 (the length of the inner ring 31 and the length of the outer ring 33) and the length L4 of the elastic body 32 is reduced. For this reason, twisting when the bush 3 is twisted is reduced. Further, the variation in torsional rigidity of the inner ring 31 and the outer ring 33 is reduced.

  As shown in FIG. 3, the housing 4 in this embodiment is a yoke of the first universal joint 84. The housing 4 fits outside the outer ring 33. The housing 4 is press-fitted outside the outer ring 33.

  As shown in FIG. 3, the stopper 6 is a substantially columnar member. The stopper 6 in this embodiment is a pin. The stopper 6 passes through the first large diameter portion 21, the inner ring 31, the elastic body 32, the outer ring 33 and the housing 4 of the shaft 2. As shown in FIGS. 3 and 4, the stopper 6 contacts the first large diameter portion 21 and the inner ring 31. On the other hand, gaps 60 are provided between the stopper 6 and the elastic body 32, between the stopper 6 and the outer ring 33, and between the stopper 6 and the housing 4. The gap 60 is annular. The presence of the gap 60 suppresses vibration transmission from the stopper 6 to the outer ring 33 and the housing 4. The vibration transmitted to the stopper 6 is not transmitted directly to the housing 4 but transmitted to the elastic body 32 and absorbed.

  The length L21 of the first large diameter portion 21 in the axial direction shown in FIG. 6 is larger than the minimum diameter D6 of the stopper 6 shown in FIG. The first large diameter portion 21 has a length L21 that can hold the stopper 6. For example, the length L 21 of the first large diameter portion 21 is 2 mm or more larger than the minimum diameter D 6 of the stopper 6. Thereby, the distance from the edge of the hole opened in the 1st large diameter part 21 in order to put the stopper 6 to the edge part of the 1st large diameter part 21 will be 1 mm or more. When the length L21 is larger than the minimum diameter D6, a portion adjacent to the first large-diameter portion 21 when the first large-diameter portion 21 is drilled (the first tapered portion 24 and the small-diameter portion 25). Deficiency is suppressed. For this reason, it is easy to form a hole for inserting the stopper 6.

  After the shaft 2, the bush 3 and the housing 4 are assembled, two holes 61 shown in FIG. 4 are opened by a step drill. Thereafter, the stopper 6 is inserted into one hole 61. The stopper 6 is a stepped pin. The stopper 6 is positioned by contacting a step provided on one end side of the stopper 6 with the inner ring 31. At this time, the other end of the stopper 6 is positioned in the other hole 61. As shown in FIG. 4, a recess 62 is provided at the other end of the stopper 6. The recess 62 is, for example, a round hole. After the step of the stopper 6 comes into contact with the inner ring 31, the concave portion 62 is expanded by a jig. Thereby, a step is formed at the other end of the stopper 6. As a result, the stopper 6 cannot be removed from the hole 61 and the coupling between the inner ring 31 and the shaft 2 is strengthened.

  Vibration applied to the shaft 2 from the road surface or the like while the vehicle is traveling is not transmitted from the stopper 6 to the housing 4 but is transmitted to the housing 4 via the inner ring 31, the elastic body 32, and the outer ring 33. For this reason, the vibration is absorbed by the elastic body 32. The elastic body 32 absorbs vibration caused by a minute displacement of the shaft 2. Thus, the buffer joint 1 can reduce the vibration transmitted to the steering wheel 81.

  On the other hand, when excessive torque is applied to the shaft 2 or the housing 4, the stopper 6 contacts the housing 4. After the shaft 2 and the housing 4 are relatively rotated by a predetermined angle, the stopper 6 comes into contact with the housing 4. The predetermined angle is, for example, about 2 ° to 5 °. The elastic body 32 is deformed until the shaft 2 and the housing 4 are relatively rotated by a predetermined angle. Thereby, the impact transmitted between the shaft 2 and the housing 4 is reduced.

  Further, when an excessive axial load is applied to the shaft 2 or the housing 4, the stopper 6 contacts the housing 4. The stopper 6 contacts the housing 4 after the shaft 2 and the housing 4 move in the axial direction relatively by a predetermined distance. The elastic body 32 is deformed until the shaft 2 and the housing 4 are relatively moved in the axial direction by a predetermined angle. Thereby, the impact transmitted between the shaft 2 and the housing 4 is reduced.

  When an excessive torque is applied to the shaft 2 or the housing 4, or when an excessive axial load is applied to the shaft 2 or the housing 4, the stopper 6 directly connects the shaft 2 and the housing 4. For this reason, the connection between the inner ring 31 and the shaft 2 needs to be strong. In the present embodiment, the stopper 6 passes through the first large diameter portion 21 of the shaft 2. Thereby, as shown in FIG. 4, the step of the stopper 6, the inner ring 31, and the shaft 2 are arranged without the gap 20. For this reason, the force with which the stage of the stopper 6 pushes the shaft 2 through the inner ring 31 is increased. As a result, the connection between the inner ring 31 and the shaft 2 is strengthened.

  The buffer joint 1 does not necessarily have to be used for connecting the first universal joint 84 and the upper shaft 85a. For example, the buffer joint 1 may be used to connect the lower shaft 85 b and the second universal joint 86. The buffer joint 1 can be widely used for connecting two members.

  The shaft 2 may not be a hollow member as described above, but may be a solid member. That is, the shaft 2 may be a substantially cylindrical member. Further, the shaft 2 may not have all the above-described configurations. The shaft 2 only needs to include at least the first large diameter portion 21, the second large diameter portion 22, and the small diameter portion 25.

  The material of the elastic body 32 is not necessarily limited to synthetic rubber, and is not particularly limited. The elastic body 32 is desirably made of a material that is easily deformed to such an extent that vibration can be absorbed.

  The stopper 6 does not necessarily have to penetrate the first large diameter portion 21. For example, the stopper 6 may penetrate the second large diameter portion 22 or the small diameter portion 25. The stopper 6 only needs to penetrate the shaft 2, the bush 3 and the housing 4. Moreover, the stopper 6 does not necessarily need to be a pin. The shape of the stopper 6 is not limited to the shape described above.

  As described above, the buffer joint 1 includes the shaft 2, the bush 3, the housing 4, and the stopper 6. The bush 3 includes a cylindrical inner ring 31 that fits outside the shaft 2, a cylindrical outer ring 33 that is positioned outside the inner ring 31, and an elastic body 32 that is positioned between the inner ring 31 and the outer ring 33. Is provided. The housing 4 fits outside the outer ring 33. The stopper 6 passes through the shaft 2, the bush 3, and the housing 4. The shaft 2 is positioned between the first large-diameter portion 21 and the second large-diameter portion 22 that are in contact with the inner ring 31, and between the first large-diameter portion 21 and the second large-diameter portion 22, and the inner diameter D 31 of the inner ring 31. A small-diameter portion 25 having a smaller outer diameter D25.

  As described above, the bush 3 is required to have the capability of absorbing minute vibrations and the capability of transmitting force when an excessive torque is applied. The bush 3 desirably has high torsional rigidity. In order to increase the torsional rigidity, it is necessary to increase the elastic force of the elastic body 32, that is, to increase the volume of the elastic body 32. However, when the volume of the elastic body 32 is increased, the elastic body 32 becomes longer in the axial direction. Along with this, the inner ring 31 and the outer ring 33 also become longer in the axial direction. On the other hand, the pressure input required when connecting the shaft 2 and the bush 3 increases according to the lengths of the inner ring 31 and the outer ring 33. When the pressure input increases, a press-fitting failure (deformation of the shaft 2 or catching between the shaft 2 and the bush 3) tends to occur. Moreover, when the pressure input increases, it is necessary to strictly manage the dimensions of the members.

  On the other hand, in the shock-absorbing joint 1 of the present embodiment, the shaft 2 includes the small-diameter portion 25, thereby reducing the effective press-fitting length when the shaft 2 and the bush 3 are connected by press-fitting. For this reason, even when the bush 3 is elongated in the axial direction in order to improve the buffer performance, the change in the inner diameter of the bush 3 (change in the tightening allowance between the shaft 2 and the bush 3) is suppressed. For this reason, variations in the press-fit load are suppressed. Therefore, the buffer joint 1 has high buffer performance and can easily connect the shaft 2 and the bush 3.

  Further, since the bush 3 is supported by the first large diameter portion 21 and the second large diameter portion 22 on both sides of the small diameter portion 25, the posture of the bush 3 with respect to the shaft 2 is stabilized. For this reason, the bush 3 is appropriately fixed to the shaft 2.

  In the buffer joint 1, the length L 3 of the bush 3 in the axial direction of the shaft 2 is larger than the outer diameter D 3 of the bush 3.

  Thereby, the buffer joint 1 is downsized and the buffer performance of the buffer joint 1 is improved.

  In the buffer joint 1, the lengths (length L3 and length L4) of the inner ring 31, the outer ring 33, and the elastic body 32 in the axial direction are not less than the length L25 of the small diameter portion 25 in the axial direction.

  Thereby, the torsional rigidity of the bush 3 is increased. The buffer joint 1 can achieve both a reduction in effective press-fitting length when the shaft 2 and the bush 3 are connected by press-fitting and a strong connection between the shaft 2 and the bush 3.

  In the buffer joint 1, the stopper 6 passes through the first large diameter portion 21 or the second large diameter portion 22.

  Thereby, compared with the case where the stopper 6 penetrates the small diameter part 25, the maximum load which can be transmitted between the shaft 2 and the stopper 6 becomes large. Further, the fatigue strength of the shaft 2 is improved.

  In the buffer joint 1, the stopper 6 passes through the first large diameter portion 21. The length L 21 of the first large diameter portion 21 in the axial direction of the shaft 2 is larger than the minimum diameter D 6 of the stopper 6.

  Thereby, the defect | deletion of the part adjacent to the 1st large diameter part 21 at the time of drilling etc. to the 1st large diameter part 21 is suppressed. For this reason, it is easy to form a hole for inserting the stopper 6.

  In the buffer joint 1, the first large-diameter portion 21 is located on the end portion side that overlaps the housing 4 of the shaft 2 with respect to the small-diameter portion 25. The shaft 2 includes a tapered portion (second tapered portion 26) whose outer diameter increases toward the second large diameter portion 22 between the small diameter portion 25 and the second large diameter portion 22 side.

  Thereby, when the shaft 2 and the bush 3 are connected by press-fitting, the shaft 2 is hardly caught on the inner peripheral surface of the inner ring 31. Therefore, the assembly of the shaft 2 and the bush 3 is facilitated.

  In the buffer joint 1, the first large-diameter portion 21 is located on the end portion side that overlaps the housing 4 of the shaft 2 with respect to the small-diameter portion 25. The 1st large diameter part 21 is provided with the end surface 21a orthogonal to an axial direction in the small diameter part 25 side.

  Thereby, the edge on the small diameter portion 25 side of the first large diameter portion 21 is easily caught on the inner peripheral surface of the inner ring 31. That is, the edge on the small diameter portion 25 side of the first large diameter portion 21 functions as a so-called return. For this reason, the bush 3 is prevented from coming off the shaft 2.

  The steering device 80 includes a buffer joint 1. Thus, the steering device 80 can suppress transmission of vibration to the steering wheel 81 and can be easily assembled.

(Modification)
FIG. 8 is a cross-sectional view of a buffer joint according to a modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 8, the shaft 2A of the modified example has a constant outer diameter at the portion overlapping the bush 3A. The bush 3A includes an inner ring 31A different from the inner ring 31 described above. The inner ring 31 </ b> A includes a first small diameter portion 311, a second small diameter portion 312, a large diameter portion 315, and a tapered portion 316.

  As shown in FIG. 8, the first small diameter portion 311 is located on the end side of the shaft 2 with respect to the large diameter portion 315. The inner diameter of the first small diameter portion 311 is constant. The first small diameter portion 311 is in contact with the shaft 2A.

  As shown in FIG. 8, the second small diameter portion 312 is located on the opposite side of the housing 4 with respect to the large diameter portion 315. The inner diameter of the second small diameter portion 312 is constant. The inner diameter of the second small diameter portion 312 is equal to the inner diameter of the first small diameter portion 311. The second small diameter portion 312 is in contact with the shaft 2A. The second small diameter portion 312 includes an end surface 312a on the large diameter portion 315 side. The end surface 312a is orthogonal to the axial direction. That is, the portion between the second small diameter portion 312 and the large diameter portion 315 is not chamfered.

  As shown in FIG. 8, the large diameter portion 315 is located between the first small diameter portion 311 and the second small diameter portion 312. The inner diameter of the large diameter portion 315 is larger than the outer diameter of the shaft 2A. There is a gap 30 between the large diameter portion 315 and the shaft 2A. The gap 30 is annular.

  The tapered portion 316 is located between the first small diameter portion 311 and the large diameter portion 315. The tapered portion 316 is adjacent to the first small diameter portion 311 and the large diameter portion 315. The inner diameter of the tapered portion 316 increases toward the large diameter portion 315. For example, the tapered portion 316 is formed by chamfering a portion between the first small diameter portion 311 and the large diameter portion 315. Thereby, when the shaft 2A and the bush 3A are connected by press-fitting, the shaft 2A is hardly caught on the inner peripheral surface of the inner ring 31A. Therefore, the assembly of the shaft 2A and the bush 3A is facilitated.

  As described above, the buffer joint 1A includes the shaft 2A, the bush 3A, the housing 4, and the stopper 6. The bush 3A includes a cylindrical inner ring 31A that fits outside the shaft 2A, a cylindrical outer ring 33 that is positioned outside the inner ring 31A, and an elastic body 32 that is positioned between the inner ring 31A and the outer ring 33. Is provided. The housing 4 fits outside the outer ring 33. The stopper 6 passes through the shaft 2 </ b> A, the bush 3 </ b> A, and the housing 4. The bush 3A is positioned between the first small diameter portion 311 and the second small diameter portion 312 that are in contact with the shaft 2A, and between the first small diameter portion 311 and the second small diameter portion 312 and has an inner diameter larger than the outer diameter of the shaft 2A. A large-diameter portion 315.

  Thereby, the effective press-fitting length when the shaft 2A and the bush 3A are connected by press-fitting is reduced. For this reason, even when the bush 3A is lengthened in the axial direction in order to improve the buffering performance, the change in the inner diameter of the bush 3A (change in the interference between the shaft 2A and the bush 3A) is suppressed. For this reason, variations in the press-fit load are suppressed. Therefore, the buffer joint 1A has high buffer performance and can easily connect the shaft 2A and the bush 3A.

DESCRIPTION OF SYMBOLS 1, 1A Buffer joint 2, 2A Shaft 20 Crevice 21 1st large diameter part 22 2nd large diameter part 24 1st taper part 25 Small diameter part 26 2nd taper part 3, 3A Bush 31,31A Inner ring 311 1st small diameter part 312 2nd small diameter portion 315 Large diameter portion 316 Tapered portion 32 Elastic body 33 Outer ring 4 Housing 6 Stopper 60 Clearance 80 Steering device 81 Steering wheel 82 Steering shaft 82a Input shaft 82b Output shaft 83 Steering force assist mechanism 84 First universal joint 85 Intermediate shaft 85a Upper shaft 85b Lower shaft 86 Second universal joint 87 Pinion shaft 88 Steering gear 88a Pinion 88b Rack 89 Tie rod 90 ECU
92 Speed reducer 93 Electric motor 94 Torque sensor 95 Vehicle speed sensor 98 Ignition switch 99 Power supply

Claims (9)

A shaft,
A bush provided with a cylindrical inner ring that fits outside the shaft, a cylindrical outer ring located outside the inner ring, and an elastic body positioned between the inner ring and the outer ring;
A housing that fits outside the outer ring;
A stopper penetrating the shaft, the bush, and the housing;
With
The shaft is positioned between the first large diameter portion and the second large diameter portion contacting the inner ring, the first large diameter portion and the second large diameter portion, and is smaller than the inner diameter of the inner ring. A buffer joint comprising: a small diameter portion having an outer diameter. The buffer joint according to claim 1, wherein a length of the bush in an axial direction of the shaft is larger than an outer diameter of the bush. The buffer joint according to claim 1, wherein lengths of the inner ring, the outer ring, and the elastic body in the axial direction of the shaft are equal to or longer than a length of the small diameter portion in the axial direction. The buffer joint according to any one of claims 1 to 3, wherein the stopper penetrates the first large diameter portion or the second large diameter portion. The stopper penetrates the first large diameter portion,
The buffer joint according to claim 4, wherein a length of the first large diameter portion in the axial direction of the shaft is larger than a minimum diameter of the stopper. The first large diameter portion is located on an end portion side of the shaft that overlaps the housing with respect to the small diameter portion,
6. The shaft according to claim 1, wherein the shaft includes a tapered portion whose outer diameter increases toward the second large diameter portion between the small diameter portion and the second large diameter portion. Buffer joint. The first large diameter portion is located on the end side of the shaft that overlaps the housing with respect to the small diameter portion,
The buffer joint according to any one of claims 1 to 6, wherein the first large-diameter portion includes an end surface orthogonal to the axial direction of the shaft on the small-diameter portion side. A shaft,
A bush provided with a cylindrical inner ring that fits outside the shaft, a cylindrical outer ring located outside the inner ring, and an elastic body positioned between the inner ring and the outer ring;
A housing that fits outside the outer ring;
A stopper penetrating the shaft, the bush, and the housing;
With
The bush has a first small diameter portion and a second small diameter portion that are in contact with the shaft, and a large diameter that is located between the first small diameter portion and the second small diameter portion and has an inner diameter larger than the outer diameter of the shaft. And a cushion joint.   A steering device comprising the shock-absorbing joint according to claim 1.

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