JP2013082359A - Neutral position recovery device of rear wheel rolling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a neutral position recovery device of a rear wheel rolling device which can reduce the discomfort of a driver.SOLUTION: A rear wheel rolling shaft 43 is recovered to a neutral position by moving a first movable member 66 and a second movable member 67 by restoring forces of a first compression coil spring 64 and a second compression spring 65 where moving speeds of cylindrical members are reduced by applying resistance to the first movable member 66 and the second movable member 67 using a hydraulic damper 80.

Description

  The present invention provides a rear wheel rotation including an elastic member that applies a force for returning the rear wheel to a neutral position to a rear wheel steering shaft, and a switching mechanism that switches between a compressed state in which the elastic member is deformed and a restored state in which the elastic member is restored. The present invention relates to a neutral position return device for a rudder device.

  The neutral position return device of the rear wheel steering device described in Patent Document 1 releases the holding of the spring by the holding mechanism when detecting a failure of the control system. Thereby, since the restoring force of the elastic member is applied to the rear wheel turning shaft, the turning shaft moves to the neutral position.

Japanese Patent Laid-Open No. 2-254062

  According to the neutral position return device, when the restoring force of the elastic member is applied to the rear wheel turning shaft, the turning angle of the rear wheel changes according to the moving speed of the rear wheel turning shaft. For this reason, when the restoring force of the elastic member is large, the driver may feel uncomfortable due to the large change speed of the turning angle of the rear wheels.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a neutral position return device for a rear wheel steering device that can reduce the driver's uncomfortable feeling.

  (1) The first means is the invention according to claim 1, that is, an elastic member that applies a force for returning the rear wheel to the neutral position to the rear wheel steering shaft, a compressed state in which the elastic member is deformed, and the elasticity A neutral position return device for a rear wheel steering device including a switching mechanism that switches between a restored state in which the member is restored, and a damper mechanism that provides resistance to the elastic member when the elastic member is in the restored state. The gist.

  According to the present invention, resistance acts on the restoring force when the elastic member is in the restoring state, so that the moving speed of the rear wheel turning shaft at the time of return is lower than in the configuration not provided with the damper mechanism. . For this reason, a driver's discomfort can be reduced.

  (2) The second means is the neutral position returning device of the invention according to claim 2, that is, the rear wheel steering device according to claim 1, wherein the damper mechanism includes a hydraulic damper, and the hydraulic damper Includes a hollow member that stores hydraulic oil, a valve body that opens or closes the hollow member, and a compression member that compresses the hydraulic oil in the hollow member, and the compression member includes the elastic member. The hydraulic fluid is compressed by a restoring force applied from the elastic member in the restored state, and the valve body closes the hollow member when the elastic member is in the compressed state, The gist is to open the hollow member as the hydraulic oil is compressed by the compression member when the member is in the restored state.

  According to this invention, since the open / close state of the hollow member by the valve body can be switched according to the state of the elastic member, the neutral position return device of the neutral position return device can be compared with the configuration in which the open / close state is switched by driving the valve body with an actuator. The configuration is simplified.

  (3) The third means is the invention according to claim 3, that is, the neutral position return device of the rear wheel steering device according to claim 2, wherein the valve body is provided as the switching mechanism. And

  According to this invention, since the valve body of the damper mechanism also has a function as a switching mechanism, the neutral position return device can be downsized as compared with the configuration in which the valve body and the switching mechanism are individually provided. .

  (4) The fourth means is the neutral position return device of the rear wheel turning device according to any one of claims 1 to 3, that is, a part of the rear wheel turning shaft. A housing that accommodates the housing, a compression coil spring as the elastic member, a movable member that moves in the axial direction of the rear wheel turning shaft relative to the housing by a restoring force of the compression coil spring, The switching mechanism switches between a restricted state that restricts movement of the movable member relative to the housing and a movable state that permits movement of the movable member relative to the housing, and the compression coil spring includes the movable member in the restricted state. When the movable member is in the compressed state, and when the movable member is in the movable state, it is in the restored state, the rear wheel turning shaft is in the movable state. The rotating force of the elastic member transmitted through the movable member causes the rear wheel to rotate toward the neutral position, and the damper mechanism moves the movable member relative to the housing. The gist is to provide resistance to the material.

  According to this invention, since the compression coil spring is used as the elastic member, the configuration of the neutral position return device is simplified. Further, since the compression coil spring is suitable for mass production, the cost of the neutral position return device is reduced.

  (5) The fifth means is the neutral position return device of the invention according to claim 5, ie, the rear wheel steering device according to claim 4 that cites claim 2 or 3, wherein the elastic member is the movable member. Applying a restoring force to each of the rear wheel steering shaft and the compression member via a member, and when the movable member is in the restricted state, the compression is performed at a position where the valve body closes the hollow member. The gist is to hold the member and move the compression member to a position where the valve element opens the hollow member when the member is in the movable state.

  According to the present invention, as the movable member changes from the restricted state to the movable state, the hollow member changes from the closed state to the opened state. For this reason, when the movable member returns the rear wheel steering shaft to the neutral position, resistance is applied to the movement of the movable member by the damper mechanism.

  ADVANTAGE OF THE INVENTION According to this invention, the neutral position return apparatus of the rear-wheel steering apparatus which can reduce a driver | operator's discomfort can be provided.

The block diagram which shows the whole structure about a rear-wheel steering apparatus provided with the neutral position return apparatus of 1st Embodiment of this invention. About the neutral position return apparatus of the embodiment, (a) is a cross-sectional view showing a cross-sectional structure of the return mechanism along the central axis, and (b) shows a cross-sectional structure of the return mechanism along the AA line of (a). Sectional drawing. In the neutral position return device of the embodiment, (a) is a cross-sectional view showing a cross-sectional structure at the start of the return operation, (b) is a cross-sectional view showing a cross-sectional structure during the return operation, and (c) is a cross-section after the return operation. Sectional drawing which shows a structure. Regarding the neutral position return device according to the second embodiment of the present invention, (a) is a cross-sectional view showing a cross-sectional structure of the return mechanism along the central axis, and (b) is a view of the return mechanism along line BB in (a). Sectional drawing which shows a cross-sectional structure. In the neutral position return device of the embodiment, (a) is a cross-sectional view showing a cross-sectional structure at the start of the return operation, (b) is a cross-sectional view showing a cross-sectional structure during the return operation, and (c) is a cross-section after the return operation. Sectional drawing which shows a structure. Sectional drawing which shows the cross-section of the return mechanism in alignment with a central axis about the neutral position return apparatus of other embodiment of this invention.

(First embodiment)
With reference to FIG. 1, the whole structure of the vehicle 1 is demonstrated.
The vehicle 1 includes a right front wheel 11, a left front wheel 12, a right rear wheel 13, a left rear wheel 14, a power supply 15, a steering wheel 16, and a steering device 20.

  The steering device 20 includes a control device 21 that controls the front wheel steering device 30 and the rear wheel steering device 40 according to the steering angle, steering torque, and traveling speed, and a steering angle that detects the rotation angle of the steering shaft 35 as a steering angle. And a sensor 22. In addition to this, a steering torque sensor 23 that detects the steering torque of the steering shaft 35, a vehicle speed sensor 24 that detects the traveling speed of the vehicle, a front wheel steering device 30 that steers the right front wheel 11 and the left front wheel 12, And a rear wheel steering device 40 that steers the right rear wheel 13 and the left rear wheel 14.

  The front wheel steering device 30 includes a front wheel steering motor 31, a speed reduction mechanism 32 that transmits the rotation of the front wheel steering motor 31 to the steering shaft 35, and a rack and pinion mechanism 34 that transmits the rotation of the steering shaft 35 to the front wheel steering shaft 33. Have Each of the right front wheel 11 and the left front wheel 12 is connected to both ends of the front wheel turning shaft 33 via a tie rod and a knuckle.

  The rear wheel turning device 40 includes a rear wheel turning motor 41 and a worm gear reduction mechanism 42 that transmits the rotation of the rear wheel turning motor 41 to the rear wheel turning shaft 43. Each of the right rear wheel 13 and the left rear wheel 14 is connected to both ends of the rear wheel turning shaft 43 via a tie rod and a knuckle. In addition to this, the rear wheel steering device 40 is a neutral position for returning the rear wheel steering shaft 43 to a position corresponding to the straight steering angle of the right rear wheel 13 and the left rear wheel 14 (hereinafter, “neutral position”). A return device 50 is included.

  The neutral position return device 50 returns the rear wheel turning shaft 43 to the neutral position in response to an instruction from the return control device 51 that determines the return timing of the rear wheel turning shaft 43 to the neutral position and the return control device 51. A return mechanism 60 is provided.

The operation of the front wheel steering device 30 will be described.
As torque is applied to the steering wheel 16 by the driver, the steering shaft 35 rotates. Torque of the front wheel steering motor 31 is applied to the steering shaft 35 via the speed reduction mechanism 32. The rotation of the steering shaft 35 is converted into a linear motion in the axial direction of the front wheel steering shaft 33 by the rack and pinion mechanism 34. The linear motion of the front wheel turning shaft 33 is transmitted to the knuckle through the tie rod. Thereby, the turning angles of the right front wheel 11 and the left front wheel 12 are changed.

Operation | movement of the rear-wheel steering apparatus 40 is demonstrated.
The rotation of the rear wheel steering motor 41 is converted by the worm gear reduction mechanism 42 into linear motion in the axial direction of the rear wheel steering shaft 43. The linear motion of the rear wheel steering shaft 43 accompanying the rotation of the rear wheel steering motor 41 is transmitted to the knuckle through the tie rod. Thereby, the turning angles of the right rear wheel 13 and the left rear wheel 14 are changed.

Processing of the control device 21 will be described.
The control device 21 calculates the torque to be applied to the steering shaft 35 based on the steering torque and the traveling speed so as to be proportional to the steering torque. The control device 21 controls the front wheel steering motor 31 so that the torque applied to the steering shaft 35 becomes the calculated torque. Further, the control device 21 controls the rear wheel steering motor 41 so that the turning angles of the right rear wheel 13 and the left rear wheel 14 are the turning angles calculated based on the steering angle.

A detailed configuration of the return mechanism 60 will be described with reference to FIG.
The first housing 61 has a direction along the central axis in the direction of the right rear wheel 13 (FIG. 1) (hereinafter “right direction”) and the direction of the left rear wheel 14 (FIG. 1) (hereinafter “left direction”). A rear wheel turning shaft 43 is inserted so as to be movable. The rear wheel turning shaft 43 in the first housing 61 is integrated with a first flange 62 that receives a return force for returning the rear wheel turning shaft 43 to the neutral position from the first movable member 66 or the second movable member 67. Formed. A stop member 63 projecting toward the radial center is provided at a position on the inner peripheral surface of the first housing 61 where the axial position coincides with the first flange 62 when the rear wheel turning shaft 43 returns to the neutral position. It has been. The width of the stop member 63 in the central axis direction of the first housing 61 is selected to be the same width as the width of the first flange 62.

  The contact member attached to a part of the rear wheel turning shaft 43 accommodated in the worm gear reduction mechanism 42 (FIG. 1) and the contact member provided in the worm gear reduction mechanism 42 are the rear wheel turning shaft 43. The worm gear speed reduction mechanism 42 is configured so as to come into contact with each other by movement in the axial direction. As a result, as shown in FIG. 2, the movable distance of the rear wheel turning shaft 43 is restricted to a predetermined distance ΔL in the right direction and the left direction with respect to the center in the axial direction of the first housing 61. .

  A first compression coil spring 64 is attached to the left end of the inner surface of the first housing 61 above and below the rear wheel turning shaft 43 in parallel with the rear wheel turning shaft 43. In addition, a second compression coil spring 65 is attached to the right end of the inner surface of the first housing 61 above and below the rear wheel turning shaft 43 in parallel with the rear wheel turning shaft 43.

  A first movable member 66 that moves the rear wheel turning shaft 43 toward the stop member 63 by receiving the restoring force of the first compression coil spring 64 at the end of the first compression coil spring 64 on the stop member 63 side. Be placed. The first movable member 66 has a second flange 66 </ b> A that receives the restoring force of the first compression coil spring 64. A rear wheel steering shaft 43 is inserted into the first movable member 66.

  A second movable member 67 that moves the rear wheel turning shaft 43 toward the stop member 63 by receiving the restoring force of the second compression coil spring 65 at the end of the second compression coil spring 65 on the stop member 63 side. Be placed. The second movable member 67 has a third flange 67A that receives the restoring force of the second compression coil spring 65. A rear wheel turning shaft 43 is inserted into the second movable member 67.

  The return mechanism 60 includes a restriction mechanism 70 that restricts movement of the first movable member 66 and the second movable member 67 relative to the first housing 61, and movement of the first movable member 66 and the second movable member 67 relative to the first housing 61. A hydraulic damper 80 is provided to provide resistance.

  The restriction mechanism 70 includes a second housing 71 provided on the upper portion of the first housing 61, a restriction member 72 that restricts the movement of the first movable member 66 and the second movable member 67 with respect to the first housing 61, and a restriction member 72. Is provided.

  A first insertion hole 74 through which the rod of the solenoid 73 can be inserted in the vertical direction is formed on the upper surface of the second housing 71. The restriction member 72 is accommodated in the second housing 71. The solenoid 73 is attached to the upper surface of the second housing 71 so that the rod is inserted.

  The first housing 61 is formed with a second insertion hole 75 into which the leading end portion of the regulating member 72 is inserted. The restricting member 72 is inserted into the second insertion hole 75 to restrict the first movable member 66 and the second movable member 67 from moving from a predetermined position toward the stop member 63. The predetermined position is a position where each of the first movable member 66 and the second movable member 67 compresses each of the first compression coil spring 64 and the second compression coil spring 65 to a predetermined compression state. Hereinafter, a state where the movement of each of the first movable member 66 and the second movable member 67 is restricted by the restriction member 72 is referred to as a restriction state. In addition, a state where the restriction state of the first movable member 66 and the second movable member 67 is released is referred to as a movable state. The state in which the first compression coil spring 64 and the second compression coil spring 65 are restored by releasing the restriction state of the first movable member 66 and the second movable member 67 is referred to as a restoration state.

  The hydraulic damper 80 includes a first hydraulic damper 90 that imparts resistance to the movement of the first movable member 66, a second hydraulic damper 100 that imparts resistance to the movement of the second movable member 67, the first hydraulic damper 90, and the second hydraulic pressure. An oil pan 82 for receiving the hydraulic oil 81 of the damper 100 and the discharged hydraulic oil 81 is provided.

  The hydraulic oil 81 is filled in the first cylinder 91 and the second cylinder 101 in advance when the first movable member 66 and the second movable member 67 are in the restricted state. The oil pan 82 is provided below the first support member 95 and the second support member 105 so as to receive the hydraulic oil 81 discharged from the second discharge hole 98 and the fourth discharge hole 108.

  The first hydraulic damper 90 compresses the first cylinder 91 that stores the hydraulic oil 81, the first piston rod 92 that moves as the first movable member 66 moves, and the hydraulic oil 81 that moves as the first piston rod 92 moves. The first piston head 93 and the first discharge hole 94 for discharging the hydraulic oil 81 of the first cylinder 91 are provided. In addition, a first valve body 97 that opens or closes the first discharge hole 94, a first spring 96 that presses the first valve body 97 against the first discharge hole 94, and a first support that supports the first spring 96. The member 95 and the second discharge hole 98 for discharging the hydraulic oil 81 of the first support member 95 from the first discharge hole 94 to the oil pan 82 are provided.

  The first cylinder 91 is disposed in the lower portion of the first housing 61 so as to face the second flange 66A from the stop member 63. The first piston head 93 is inserted into the first cylinder 91. The first piston head 93 is connected to the second flange 66 </ b> A via the first piston rod 92.

The first spring 96 presses the first valve body 97 toward the first discharge hole 94. The second discharge hole 98 is formed so as to penetrate the lower portion of the first support member 95.
The second hydraulic damper 100 compresses the second cylinder 101 that stores the hydraulic oil 81, the second piston rod 102 that moves as the second movable member 67 moves, and the hydraulic oil 81 that moves as the second piston rod 102 moves. The second piston head 103 and the third discharge hole 104 for discharging the hydraulic oil 81 of the second cylinder 101. In addition, the second valve body 107 that opens or closes the third discharge hole 104, the second spring 106 that presses the second valve body 107 against the third discharge hole 104, and the second support that supports the second spring 106 are provided. The member 105 and the fourth discharge hole 108 for discharging the hydraulic oil 81 discharged from the third discharge hole 104 to the second support member 105 to the oil pan 82 are provided.

  The second cylinder 101 is disposed in the lower portion of the first housing 61 so as to face the third flange 67A from the stop member 63. The second piston head 103 is inserted into the second cylinder 101. The second piston head 103 is connected to the third flange 67A via the second piston rod 102.

The second spring 106 presses the second valve body 107 toward the third discharge hole 104. The fourth discharge hole 108 is formed so as to penetrate the lower portion of the second support member 105.
With reference to FIG. 3, the operation of the neutral position return device 50 when the rear wheel turning shaft 43 returns to the neutral position from the state of moving leftward will be described.

  The return control device 51 detects the disconnection of the electric wire that supplies power from the power source 15 (FIG. 2) to the control device 21 (FIG. 2) as a failure of the control device 21 so that the restriction member 72 rises. To drive. Thereby, the regulating member 72 is pulled out from the second insertion hole 75. As shown in FIG. 3 (a), the first movable member 66 and the second movable member 67 are released from the restricted state, and become movable. Further, the first compression coil spring 64 and the second compression coil spring 65 are restored.

  The first movable member 66 receives the restoring force of the first compression coil spring 64 in the restored state by the second flange 66A. The second movable member 67 receives the restoring force of the second compression coil spring 65 in the restored state by the third flange 67A. The first movable member 66 moves in the axial direction of the rear wheel turning shaft 43 with respect to the first housing 61 while receiving the restoring force of the first compression coil spring 64 and the resistance of the first hydraulic damper 90. The second movable member 67 moves in the axial direction of the rear wheel turning shaft 43 with respect to the first housing 61 while receiving the restoring force of the second compression coil spring 65 and the resistance of the second hydraulic damper 100.

  As shown in FIG. 3B, when the first movable member 66 continues to move, it comes into contact with the first flange 62. As shown in FIG. 3C, after the first movable member 66 and the first flange 62 are in contact, the first movable member 66 and the first flange are in contact until the first movable member 66 is in contact with the stop member 63. 62 and the rear wheel turning shaft 43 are moved together in the right direction. As a result, the rear wheel turning shaft 43 returns to the neutral position. The second movable member 67 moves until it comes into contact with the stop member 63.

Details of operations of the first hydraulic damper 90 and the second hydraulic damper 100 will be described.
When the first movable member 66 enters the movable state and starts to move, the pressure in the first cylinder 91 increases according to the amount of movement of the first movable member 66. When movement starts when the second movable member 67 becomes movable, the pressure in the second cylinder 101 increases in accordance with the amount of movement of the second movable member 67.

  As shown in FIG. 3B, when the pressure in the first cylinder 91 exceeds the regulation value determined by the restoring force of the first spring 96, the first valve body 97 is pushed back. Thereby, the first cylinder 91 is opened. When the pressure in the second cylinder 101 exceeds a regulation value determined by the restoring force of the second spring 106, the second valve body 107 is pushed back. As a result, the second cylinder 101 is opened.

  When the first cylinder 91 is opened, the hydraulic oil 81 is discharged from the first cylinder 91. When the second cylinder 101 is opened, the hydraulic oil 81 is discharged from the second cylinder 101. As shown in FIG. 3C, the hydraulic oil 81 of the first cylinder 91 is discharged until the first movable member 66 contacts the stop member 63. The hydraulic oil 81 in the second cylinder 101 is discharged until the second movable member 67 contacts the stop member 63.

  The resistance that the first piston head 93 that moves with the movement of the first movable member 66 compresses the hydraulic oil 81 in the first cylinder 91 receives the resistance through the first piston head 93 and the first piston rod 92. It is transmitted to the first movable member 66. As a result, the moving speed of the first movable member 66 is lower than when the resistance is not transmitted. The resistance that the second piston head 103 moving with the movement of the second movable member 67 compresses the hydraulic oil 81 in the second cylinder 101 receives via the second piston head 103 and the second piston rod 102. It is transmitted to the second movable member 67. Thereby, the moving speed of the 2nd movable member 67 falls rather than the time when resistance is not transmitted.

  When the rear wheel turning shaft 43 is moved rightward from the neutral position, when returning to the neutral position, the rear wheel turning shaft 43 is moved until the second movable member 67 contacts the stop member 63. Let

(Effect of embodiment)
According to the neutral position return device 50 of the present embodiment, the following effects can be obtained.
(1) The neutral position return device 50 includes a hydraulic damper 80 that applies resistance to the first movable member 66 and the second movable member 67 when the first compression coil spring 64 and the second compression coil spring 65 are in a restored state. Is provided.

  According to this configuration, resistance acts against the restoring force when the first compression coil spring 64 and the second compression coil spring 65 are in the restoration state, so that the return is made in comparison with the configuration without the hydraulic damper 80. The moving speed of the rear wheel turning shaft 43 at that time becomes small. Thereby, a driver's discomfort can be reduced.

  (2) The first valve body 97 and the second valve body 107 close the first cylinder 91 and the second cylinder 101 when the first compression coil spring 64 and the second compression coil spring 65 are in the compressed state. On the other hand, when the first compression coil spring 64 and the second compression coil spring 65 are in the restored state, the first cylinder 91 and the second cylinder 91 are compressed as the hydraulic oil 81 is compressed by the first piston head 93 and the second piston head 103. The cylinder 101 is opened.

  According to this configuration, the configuration of the neutral position return device 50 can be simplified as compared with the configuration in which the first valve element 97 and the second valve element 107 are driven by the actuator to switch the open / close state.

  (3) When the first movable member 66 and the second movable member 67 are in a movable state, the rear wheel turning shaft 43 is transmitted through the movable members 66 and 67 through the first compression coil spring 64 and the second compression. The right rear wheel 13 and the left rear wheel 14 are rotated toward the neutral position by the restoring force of the coil spring 65. The hydraulic damper 80 gives resistance to the first movable member 66 and the second movable member 67 that move relative to the first housing 61.

  According to this configuration, since the compression coil spring is used as the member for applying the restoring force to the movable members 66 and 67, the configuration of the neutral position return device 50 is simplified. Further, since the compression coil spring is suitable for mass production, the cost of the neutral position return device 50 is reduced.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. The neutral position return device 110 of the present embodiment corresponds to the neutral position return device 50 of the first embodiment with the following changes. That is, in the return mechanism 60 of the first embodiment, the regulating mechanism 70 and the hydraulic damper 80 are configured separately. On the other hand, in the return mechanism 120 of the present embodiment, the restriction mechanism and the hydraulic damper are integrally configured.

  Hereinafter, the configuration of the neutral position return device 110 of the present embodiment will be described focusing on the changes from the first embodiment. In addition, about the structure which is common in 1st Embodiment, the same code | symbol is attached | subjected and the one part or all part of the description is abbreviate | omitted suitably.

  The neutral position return device 110 includes a return mechanism 120 instead of the return mechanism 60 of the neutral position return device 50. The return mechanism 120 is provided with a hydraulic damper 130 and a regulating mechanism 160 in place of the regulating mechanism 70 and the hydraulic damper 80.

  The hydraulic damper 130 includes a third damper 140 that applies resistance to the movement of the first movable member 66, a fourth damper 150 that applies resistance to the movement of the second movable member 67, and the third damper 140 and the fourth damper 150. Hydraulic oil 81, a protruding portion 131 for forming a discharge path for the hydraulic oil 81 therein, and an oil pan 132 for receiving the discharged hydraulic oil 81.

  When the hydraulic oil 81 is compressed to a predetermined compression state by the first movable member 66 and the second movable member 67, the third cylinder 141, the fourth cylinder 151, the first conduit 144, the second conduit 154, and The discharge pipe 161 is filled in advance. The protruding portion 131 has a rectangular parallelepiped shape that protrudes downward from the lower portion of the first housing 61. The oil pan 132 is provided below the protrusion 131 so as to receive the hydraulic oil 81 discharged from the discharge path of the hydraulic oil 81 formed inside the protrusion 131.

  The third damper 140 compresses the hydraulic oil 81 in accordance with the movement of the third cylinder 141 that stores the hydraulic oil 81, the third piston rod 142 that moves as the first movable member 66 moves, and the movement of the third piston rod 142. 3 piston head 143 and the 1st conduit | pipe 144 used as the flow path of the hydraulic oil 81 of the 3rd cylinder 141 are provided.

  The third cylinder 141 has an annular cross section along the inner peripheral surface of the first housing 61, and is formed to face the first movable member 66 from the stop member 63. The third piston head 143 is formed in an annular shape so that the third cylinder 141 can be sealed. The third piston head 143 is inserted into the third cylinder 141. The third piston rod 142 connects the third piston head 143 and the second flange 66A at two locations, an upper portion and a lower portion. The first conduit 144 is formed to extend downward from the end of the third cylinder 141 on the stop member 63 side toward the protrusion 131.

  The fourth damper 150 compresses the hydraulic oil 81 as the fourth piston rod 152 moves, the fourth piston rod 152 moves as the fourth cylinder 151 stores the hydraulic oil 81, the second movable member 67 moves, and the fourth piston rod 152 moves. 4 piston head 153 and the 2nd conduit | pipe 154 used as the flow path of the hydraulic oil 81 of the 4th cylinder 151 are provided.

  The fourth cylinder 151 has an annular cross section along the inner peripheral surface of the first housing 61, and is formed to face the second movable member 67 from the stop member 63. The fourth piston head 153 is formed in an annular shape so that the fourth cylinder 151 can be sealed. The fourth piston head 153 is inserted into the fourth cylinder 151. The fourth piston rod 152 connects the fourth piston head 153 and the third flange 67A at two locations, an upper portion and a lower portion. The second conduit 154 is formed so as to extend downward from the end of the fourth cylinder 151 on the stop member 63 side toward the protrusion 131.

  The restriction mechanism 160 includes a discharge pipe 161 that discharges the hydraulic oil 81 flowing out from the first conduit 144 and the second conduit 154, a discharge chamber 162 that discharges the hydraulic oil 81 discharged from the discharge pipe 161 to the oil pan 132, and a discharge pipe. A third valve body 163 that opens or closes 161 and a third spring 164 that presses the third valve body 163 against the discharge pipe 161 with a restoring force are provided. In addition, a solenoid 165 that presses the third valve body 163 against the discharge pipe 161 with a driving force, and a fifth discharge hole 167 that discharges the hydraulic oil 81 discharged to the discharge chamber 162 to the oil pan 132 are provided. .

  The discharge pipe 161 has a circular cross section. The discharge pipe 161 is formed inside the protrusion 131 so as to extend in parallel with the central axis of the first housing 61 from the lower end of the second conduit 154 toward the lower end of the first conduit 144. The discharge chamber 162 is formed inside the protrusion 131 so as to have a shape that expands the diameter of the discharge pipe 161 and extends in the central axis direction at the outlet of the discharge pipe 161.

  The solenoid 165 is attached to the opening of the discharge chamber 162 in the protruding portion 131 so as to face the discharge tube 161 so that the third valve body 163 can be pressed against the discharge tube 161.

  The third valve body 163 is formed in a spherical shape. The third spring 164 presses the third valve body 163 against the discharge pipe 161 by a restoring force. The fifth discharge hole 167 is formed so as to penetrate the lower portion of the discharge chamber 162.

  The third valve body 163 is pressed against the discharge pipe 161 by the solenoid 165 so that the hydraulic oil 81 is not discharged from the discharge pipe 161 in a state where the hydraulic oil 81 is filled. Thereby, it will be in the regulation state where each movement of the 1st movable member 66 and the 2nd movable member 67 by the restoring force of the 1st compression coil spring 64 and the 2nd compression coil spring 65 is regulated.

With reference to FIG. 5, the operation of the neutral position return device 110 when the rear wheel turning shaft 43 returns to the neutral position from the state of moving leftward will be described.
The return control device 51 (FIG. 4) discharges the third valve body 163 when the disconnection of the electric wire supplying power from the power source 15 (FIG. 4) to the control device 21 (FIG. 4) is detected as a failure of the control device 21. The driving force pressed against the tube 161 is released. As shown to Fig.5 (a), the 1st movable member 66 and the 2nd movable member 67 will be in a movable state. Further, the first compression coil spring 64 and the second compression coil spring 65 are restored.

  The first movable member 66 receives the restoring force of the first compression coil spring 64 in the restored state by the second flange 66A. The second movable member 67 receives the restoring force of the second compression coil spring 65 in the restored state by the third flange 67A. The first movable member 66 moves in the axial direction of the rear wheel turning shaft 43 with respect to the first housing 61 while receiving the restoring force by the first compression coil spring 64 and the resistance by the third damper 140. The second movable member 67 moves in the axial direction of the rear wheel turning shaft 43 with respect to the first housing 61 while receiving the restoring force of the second compression coil spring 65 and the resistance of the fourth damper 150.

  As shown in FIG. 5B, when the first movable member 66 continues to move, it comes into contact with the first flange 62. As shown in FIG. 5C, after the first movable member 66 and the first flange 62 are in contact, the first movable member 66 and the first flange are in contact until the first movable member 66 contacts the stop member 63. 62 and the rear wheel turning shaft 43 are moved together in the right direction. As a result, the rear wheel turning shaft 43 returns to the neutral position. The second movable member 67 moves until it comes into contact with the stop member 63.

Details of operations of the third damper 140 and the fourth damper 150 will be described.
When the movement starts when the first movable member 66 becomes movable, the pressure in the third cylinder 141 and the first conduit 144 increases according to the amount of movement of the first movable member 66. When movement starts when the second movable member 67 becomes movable, the pressure in the fourth cylinder 151 and the second conduit 154 increases according to the amount of movement of the second movable member 67.

  As the pressure in the first conduit 144 and the second conduit 154 increases, the pressure in the discharge pipe 161 increases. As shown in FIG. 5B, when the pressure in the discharge pipe 161 exceeds the regulation value determined by the restoring force of the third spring 164, the third valve body 163 is pushed back. Thereby, the discharge pipe 161 is opened.

  When the discharge pipe 161 is opened, the hydraulic oil 81 is discharged from the third cylinder 141 and the fourth cylinder 151. As shown in FIG. 5C, the hydraulic oil 81 of the third cylinder 141 is discharged until the first movable member 66 contacts the stop member 63. The hydraulic oil 81 in the fourth cylinder 151 is discharged until the second movable member 67 contacts the stop member 63.

  The resistance that the third piston head 143 that moves with the movement of the first movable member 66 compresses the hydraulic oil 81 in the third cylinder 141 receives via the third piston head 143 and the third piston rod 142. It is transmitted to the first movable member 66. As a result, the moving speed of the first movable member 66 is lower than when the resistance is not transmitted. The resistance that the fourth piston head 153 that moves with the movement of the second movable member 67 compresses the hydraulic oil 81 in the fourth cylinder 151 receives via the fourth piston head 153 and the fourth piston rod 152. It is transmitted to the second movable member 67. Thereby, the moving speed of the 2nd movable member 67 falls rather than the time when resistance is not transmitted.

  When the rear wheel turning shaft 43 is moved rightward from the neutral position, when returning to the neutral position, the rear wheel turning shaft 43 is moved until the second movable member 67 contacts the stop member 63. Let

(Effect of embodiment)
According to the neutral position return device 110 of this embodiment, in addition to the effects (1) to (3) of the first embodiment, the following effects can be obtained.

(4) The neutral position return device 110 is provided with a third valve body 163 as the restriction mechanism 160.
According to this configuration, the restriction mechanism 160 and the hydraulic damper 130 can be integrally formed, and the neutral position return device 110 can be reduced in size compared to a configuration in which these mechanisms are provided independently. be able to.

(Other embodiments)
The embodiment of the present invention is not limited to the above embodiment, and can be modified as shown below, for example. The following modifications are not applied only to the above-described embodiment, and different modifications can be implemented in combination.

  In the first and second embodiments (FIG. 2), the hydraulic damper using the working oil 81 as the working fluid is used as the damper mechanism, but any other working fluid such as a pneumatic damper using a gas such as air as the working fluid. A damper mechanism using can also be used.

  In the first and second embodiments (FIGS. 3 and 5), when the restricted state is released, both the first movable member 66 and the second movable member 67 are made movable. It is also possible to adopt a configuration in which the movable state is made. Like the restriction mechanism 180 shown in FIG. 6, each of the first deformation restriction member 181 and the second deformation restriction member 182 obtained by deforming the restriction member 72 of the first embodiment is driven by two solenoids 183 and 184. Thus, the restricted states of the first movable member 66 and the second movable member 67 can be individually released.

  -In 1st and 2nd embodiment (FIG. 2, FIG. 4), when the return control apparatus 51 detected the disconnection of the electric wire which supplies electric power from the power supply 15 to the control apparatus 21, the restriction | limiting state was cancelled | released, but a steering angle When the output from at least one of the sensor 22, the steering torque sensor 23, and the vehicle speed sensor 24 is detected to be interrupted, the restricted state can be canceled.

  61 ... first housing (housing), 64 ... first compression coil spring (elastic member), 65 ... second compression coil spring (elastic member), 66 ... first movable member (movable member), 67 ... second movable member (Movable member), 70, 160, 180 ... restriction mechanism (switching mechanism), 80, 130 ... hydraulic damper (damper mechanism), 91 ... first cylinder (hollow member), 101 ... second cylinder (hollow member), 93 ... 1st piston head (compression member), 103 ... 2nd piston head (compression member), 97 ... 1st valve body (valve body), 107 ... 2nd valve body (valve body), 141 ... 3rd cylinder (hollow) Member), 143 ... third piston head (compression member), 151 ... fourth cylinder (hollow member), 153 ... fourth piston head (compression member), 163 ... third valve body (valve body).

Claims (5)

A rear wheel steering device including an elastic member that applies a force for returning the rear wheel to a neutral position to the rear wheel steering shaft, and a switching mechanism that switches between a compressed state in which the elastic member is deformed and a restored state in which the elastic member is restored. In the neutral position return device,
A neutral position return device for a rear wheel steering device, comprising: a damper mechanism that applies resistance to the elastic member when the elastic member is in a restored state. In the neutral position return device of the rear wheel steering device according to claim 1,
A hydraulic damper as the damper mechanism;
The hydraulic damper includes a hollow member that stores hydraulic oil, a valve body that opens or closes the hollow member, and a compression member that compresses the hydraulic oil in the hollow member.
The compression member compresses the hydraulic oil by a restoring force applied from the elastic member when the elastic member is in the restored state;
In addition, the valve body closes the hollow member when the elastic member is in the compressed state, and the hollow as the hydraulic oil is compressed by the compression member when the elastic member is in the restored state. A neutral position return device for a rear wheel steering device, wherein the member is opened. In the neutral position return device of the rear wheel steering device according to claim 2,
The valve body is provided as the switching mechanism. A neutral position return device for a rear wheel steering device. In the neutral position return device of the rear wheel steering device according to any one of claims 1 to 3,
A housing for accommodating a part of the rear wheel steering shaft;
A compression coil spring as the elastic member;
A movable member that moves in the axial direction of the rear wheel turning shaft with respect to the housing by a restoring force of the compression coil spring;
The switching mechanism switches between a restricted state that restricts movement of the movable member relative to the housing and a movable state that permits movement of the movable member relative to the housing;
The compression coil spring is in the compressed state when the movable member is in the restricted state, and is in the restored state when the movable member is in the movable state;
The rear wheel turning shaft rotates the rear wheel toward the neutral position by a restoring force of the elastic member transmitted through the movable member when the movable member is in the movable state.
In addition, the damper mechanism imparts resistance to the movable member that moves relative to the housing. Neutral position return device for a rear wheel steering device. In the neutral position return device of the rear wheel steering device according to claim 4 quoting claim 2 or 3,
The elastic member applies a restoring force to each of the rear wheel steering shaft and the compression member via the movable member;
In addition, the movable member holds the compression member at a position where the valve body closes the hollow member when in the restricted state, and at a position where the valve body opens the hollow member when in the movable state. A neutral position return device for a rear wheel steering device, wherein the compression member is moved.

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