JP4356835B2 - Vehicle seat - Google Patents

Description

  The present invention provides a vehicle seat that relieves an impact when a vehicle undergoes a rear collision (collision from the rear), and intends to suppress the onset of whiplash.

2. Description of the Related Art Conventionally, a configuration is known in which a backrest seat is attached to a seat seat so as to be movable rearward, and when the vehicle is rearwardly bumped, the backrest seat is moved rearward to reduce the impact (see Patent Document 1).
Japanese Patent Laid-Open No. 2001-1821

In the known example, only the dorsal seat moves backward, so that there is a problem that the backward movement distance is not sufficient and the impact mitigation effect is small.
In addition, since the known example simply moves the dorsal fin sheet backward, there is a problem that the head cannot be supported and may cause whiplash.
In the present application, by devising the configuration of the slide rail provided between the vehicle seat and the vehicle body, the entire vehicle seat is moved backward, the rearward movement tries to absorb the impact, and the head is supported. It is something that can be done.

In the present invention, a vehicle seat 1 is attached to a vehicle body 6 via a slide rail 5 so that the front and rear positions thereof can be adjusted. The locking device 10 of the slide rail 5 can be used at a desired position in normal seat position adjustment. When the predetermined load is applied, the lock is automatically released and the rearward movement of the vehicle seat 1 is allowed, and the lock device 10 is unlocked. A shock absorber 40 is provided to provide resistance to the rearward movement of the vehicle seat 1, and the headrest 4 of the vehicle seat 1 is interlocked with the rearward movement of the vehicle seat 1 when the vehicle receives a rear collision. it is obtained by the headrest 4 and configured the vehicle seat to move forward.
In the present invention, a vehicle seat 1 is attached to a vehicle body 6 via a slide rail 5 so that the front and rear positions thereof can be adjusted. The locking device 10 of the slide rail 5 can be used at a desired position in normal seat position adjustment. When the predetermined load is applied, the lock is automatically released and the rearward movement of the vehicle seat 1 is allowed, and the lock device 10 is unlocked. A shock absorber 40 that provides resistance to the backward movement of the vehicle seat 1 is provided, and the headrest 4 of the vehicle seat 1 has a wire 51 for the backward movement of the vehicle seat 1 when the vehicle receives a rear collision. Thus, the vehicle seat is configured to transmit the headrest 4 forward.
In the present invention, the shock absorber 40 is provided between the vehicle seat 1 and the vehicle body 6, and the headrest 4 is provided so as to be pivotable in the front-rear direction by the link mechanism 50 with respect to the dorsal seat 2. The link mechanism 50 transmits the rearward movement of the vehicle seat 1 to the headrest 4 through the wire 51 when the vehicle receives a rear collision, and the headrest 4 is interlocked with the rearward movement of the vehicle seat 1. The vehicle seat is configured to rotate forward.
According to the present invention, in the shock absorber 40, the piston rod 44 of the viscous damper 41 does not give resistance to the back and forth movement of the vehicle seat 1 in normal seat position adjustment, and a predetermined load is applied to the vehicle seat 1. When applied, the vehicle seat is configured to be coupled to the slide rail 5 so as to give resistance to the backward movement of the vehicle seat 1.
In the present invention, the shock absorber 40 includes an engagement moving body 46 in which a plurality of engagement grooves 45 are formed in the piston rod 44 of the viscous damper 41 integrally or separately in the sliding direction. An engagement hook 47 is provided on the upper rail 8 of the slide rail 5 so as to be movable by a predetermined distance, and a wire 51 for transmitting a load for operating the link mechanism 50 between the shock absorber 40 and the link mechanism 50. It is set as the vehicle seat which provided.
In the present invention, the engagement hook 47 is attached to the attachment shaft 23 so as to be rotatable and slidable for a predetermined distance, and the wire 51 connected to the end portion of the link mechanism 50 is connected to the engagement hook 47. It is a thing.
In the present invention, the transmission arm 24 and the arm 22 of the slide lock releasing link mechanism 21 are fixed to the mounting shaft 23 to which the engagement hook 47 is attached, and the arm 22 includes the lock piece 12 of the lock device 10, The lock piece 12 is connected so as to be retracted and rotated from the engagement hole 11, and the engagement hook 47 is slidably provided between the arm 22 of the mounting shaft 23 and the transmission arm 24. The transmission arm 24 is a vehicle seat configured to also serve as a stopper mechanism for the engagement hook 47.

According to the first aspect of the present invention, the headrest 4 can be rotated forward to support the head while moving the entire vehicle seat 1 backward to absorb the impact, and an impact mitigation effect and a whiplash prevention effect can be expected. Moreover, since in conjunction with the rearward movement of the vehicle seat 1 is forward movement of the headrest 4, rather good only to improve the slide rail 5, it is easy to implemented.
According to the invention of claim 2, the headrest 4 can be rotated forward to support the head while moving the entire vehicle seat 1 backward to absorb the impact, and the impact mitigation effect and the whiplash prevention effect can be expected. Since the rear movement of the seat 1 is transmitted by the wire 51 and the headrest 4 is moved forward, it is only necessary to improve the slide rail 5 and add the wire 51, and the implementation is easy.
In the invention of claim 3 , the forward moving mechanism of the headrest 4 using the inertial load when the vehicle receives a rear collision can be simply configured.
According to the fourth aspect of the present invention, it is possible to simply realize a configuration in which the front and rear positions of the vehicle seat 1 can be adjusted and the entire seat 1 is moved backward to absorb the impact.
In the invention of claim 5 , since it operates when a rear impact is predicted by the prediction system S, the prevention effect of whiplash is high, and the shock absorber 40 and the link mechanism 50 are reliably linked by the wire 51. More effective.
In the invention of claim 6, the engagement hook 47 can also serves as the traction member of switching on and off the switching member and the wire 51 of the shock absorber 40, to ensure the operation, can lower the production cost.
In the invention of claim 7 , a rational configuration can be achieved, the operation can be ensured, and the manufacturing cost can be reduced.

  An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a vehicle seat, 2 denotes a back seat of the vehicle seat 1, 3 denotes a seat seat, and 4 denotes a headrest provided on the upper portion of the back seat 2. The vehicle seat 1 is attached to a vehicle body 6 by a slide rail 5 so that the front and rear position thereof can be adjusted.

  The lower rail 7 of the slide rail 5 is fixed to the vehicle body 6, and the upper rail 8 of the slide rail 5 is slidably fitted to the lower rail 7. A lock device 10 is provided between the lower rail 7 and the upper rail 8 to stop the sliding of the upper rail 8 with respect to the lower rail 7.

  The lock device 10 fixes the vehicle seat 1 at a desired position during normal front-rear position adjustment. However, when a predetermined load is applied, the lock device 10 automatically releases the lock and moves the vehicle seat 1 backward. Configure to allow.

  The configuration of the locking device 10 is arbitrary, but as an example, the rotating rod 13A of the operating lever 13 is disposed in the upper rail 8, and the engaging rod 11 of the lower rail 7 and the upper rail are provided on the rotating rod 13A. The main lock piece 12 having the main engagement claw 12A to be engaged with and disengaged from the eight engagement holes 35 is attached. A plurality of engaging holes 11 and 35 are arranged in parallel in the sliding direction of the rails 7 and 8. The main lock piece 12 is formed with a shaft tube portion 14 at both front and rear ends, and the rotating rod 13 is rotatably inserted into the shaft tube portion 14. A semi-cylindrical rotation guide portion 15 is provided between the shaft tube portion 14 and the shaft tube portion 14.

  The base portion of the operating arm 16 is fixed to the shaft tube portion 14, and the operating arm 16 is attached to the elongated hole 18 of the operating rod 17. When the prediction system S that predicts a collision from the rear in advance by a radar or the like provided at a desired position of the vehicle body via the slide lock releasing link mechanism 21 predicts a rear collision, the operating rod 17 has a main engagement claw 12A. Is connected to an actuator 20 such as a motor / solenoid that retreats from the engagement hole 11.

  The slide lock releasing link mechanism 21 of the embodiment attaches the tip end of the arm 22 to the operating rod 17, and the base of the arm 22 is fixed to a mounting shaft 23 provided on a bracket 26 fixed to the upper rail 8. A transmission arm 24 is provided on the mounting shaft 23, and the actuator 25 of the actuator 20 is connected to the tip of the transmission arm 24.

  A radar or the like that senses the approach of a vehicle or the like from behind is provided at a desired position of the vehicle body, and a prediction system S that predicts a collision in advance is mounted. The actuator 20 is actuated by a collision prediction signal from the prediction system S, and the actuator 20 rotates the main lock piece 12 of the lock device 10 clockwise in FIG. 6 via the slide lock releasing link mechanism 21 to move the main engagement claw 12A. The main lock piece 12 of the lock device 10 is automatically unlocked by retracting from the engagement hole 11 of the lower rail 7.

  Therefore, when the main lock piece 12 is automatically released from the engagement hole 11 by the prediction system S, the locking device 10 holds (supports) the vehicle seat 1 in a predetermined position until a predetermined load is applied. A sub-block piece 28 is provided. The sub-lock piece 28 is provided with a sub-engaging claw 30 that engages with the engaging holes 11 and 35. The sub-engaging claw 30 has a rear edge formed on an inclined surface 29 having a predetermined angle. When a predetermined load is applied to the sub-block piece 28, the sub-engaging claw 30 is guided by the inclined surface 29 and the sub-engaging claw 30 is engaged with the engaging holes 11, 35. It is configured to evacuate from. The sub-block piece 28 is fixedly provided on the rotating rod 13 </ b> A of the operation lever 13 between the shaft tube portion 14 of the main lock piece 12.

  When the operation lever 13 is manually operated, the sub-block piece 28 is configured to rotate clockwise in FIG. 6 to be connected / disengaged from the engagement hole 11, and in conjunction with the rotation of the sub-block piece 28 (pressed). The main lock piece 12 is also unlocked and the lock mechanism 10 is unlocked. On the other hand, when the actuator 20 of the prediction system S is operated, only the main lock piece 12 is unlocked and rotated with respect to the rotary rod 13A of the operation lever 13, and the sub-block piece 28, the engagement hole 11, and the like. The engagement is continued. In this state, when a predetermined rearward load is applied to the vehicle seat 1 (sub-block piece 28), the inclined surface 29 of the sub-engaging claw 30 slides with respect to the engaging hole 11 and the sub-engaging claw 30. Is disengaged from the engaging hole 11, the entire locking device 10 is unlocked, and the vehicle seat 1 is moved backward by the slide rail 5.

  Therefore, a shock absorber 40 is provided between the vehicle seat 1 and the vehicle body 6 to reduce the impact of the rearward movement of the vehicle seat 1 when the lock device 10 is automatically unlocked. The shock absorber 40 fixes the cylinder 42 of the viscous body damper 41 to the vehicle body 6, encloses the viscous fluid or viscous elastic body D in the cylinder 42, and fits the piston 43 into the cylinder 42 encapsulating the viscous fluid or viscous elastic body D. Then, an engagement moving body 46 having a plurality of engagement grooves 45 formed in the sliding direction is attached to the piston rod 44 of the piston 43. The engagement moving body 46 is movably attached to the lower rail 7 together with the upper rail 8, and an engagement hook 47 that is connected to and disengaged from the engagement groove 45 of the engagement movement body 46 is fixed to the attachment shaft 23.

  The engagement hook 47 does not engage with the engagement groove 45 when the front / rear position of the vehicle seat 1 is adjusted, but engages with the engagement groove 45 when the actuator 20 is operated by predicting a rear collision. Therefore, even if the locking device 10 is automatically unlocked and the rearward movement of the vehicle seat 1 is started, the engagement hook 47 moves rearward together with the piston rod 44, and at this time, the piston 43 moves the oil in the cylinder 42. The resistance is applied to the rearward movement of the vehicle seat 1 to reduce the impact.

  The viscous damper 41 gives the piston 43 contact resistance with the viscous fluid or the viscous elastic body D in the cylinder 42 (viscous fluid due to sliding of the piston 43 or shear resistance of the viscous elastic body D), and the moving speed of the piston 43. The viscous fluid or the viscous elastic body D has a property of increasing in proportion to the viscosity, and when the piston 43 moves at high speed accompanying the automatic unlocking of the locking device 10, the viscosity increases and the resistance increases. When the piston 43 moves when the vehicular seat 1 moved to the rear side is returned to the front side, the viscosity becomes lower and the resistance becomes smaller.

  Thus, the headrest 4 is provided so as to be pivotable in the front-rear direction by the link mechanism 50 with respect to the dorsal seat 2, and uses the inertial force of the vehicle seat 1 when the vehicle receives a rear collision. 4 is moved forward to support the head moving backward, and the shock absorber 40 is configured to relieve the impact by sliding the entire vehicle seat 1 backward.

One end of the wire 51 is locked to the link mechanism 50, the other end of the wire 51 is locked to the engagement hook 47 side, and the engagement hook 47 slides on the mounting shaft 23 to which the engagement hook 47 is attached. Install freely.
That is, when a rear impact is predicted by the prediction system S, the locking device 10 of the slide rail 5 is unlocked and the upper rail 8 can be moved backward, while the upper hook 8 is engaged with the engagement hook 47. The engagement hook 47 is slid with respect to the mounting shaft 23 and the wire 51 relatively rotates the headrest 4 forward via the link mechanism 50, whereby the headrest 4 is engaged. 4 supports the head, and when the engagement hook 47 slides and hits the base of the transmission arm 24, the engagement hook 47 pulls the engagement moving body 46 from the viscous damper 41, and the vehicle seat 1 At the same time, the piston rod 44 is moved backward via the engagement moving body 46, and the piston rod 44 moves the piston 43 backward against the viscous fluid in the cylinder 42 or the contact resistance with the viscous elastic body D. It is allowed, reducing the speed of the backward movement of the vehicle seat 1 by the resistance of the viscous fluid or viscous elastic bodies D, and cushion the impact.

The link mechanism 50 is rotatably attached to both sides of the lateral mounting shaft 60 to the frame 61 of the back seat 2, the lateral mounting shaft 60 is provided with an eccentric shaft portion 62 at the center, and the pillar of the headrest 4 is provided on the eccentric shaft portion 62. 63 is fixed, a base portion of an arm 64 positioned on the opposite side of the eccentric shaft portion 62 is fixed to one side of the lateral mounting shaft 60, and the wire 51 is locked to the tip of the arm 64.
In this case, the eccentric shaft portion 62 and the tip of the arm 64 rotate relative to each other in the lateral mounting shaft 60 in the side view, and the headrest 4 is configured to rotate forward when the arm 64 is pulled. It is not limited to this, and the load of the rearward movement of the vehicle seat 1 may be converted into the forward rotation of the headrest 4.

Next, the operation of the embodiment will be described.
(Front / back adjustment mode)
When the operation lever 13 of the locking device 10 is operated, the sub-block piece 28 is rotated downward together with the operation lever 13, and the main lock piece 12 is also rotated downward in conjunction with this, so that the sub-block piece 28 and the main lock piece 12 are moved. The lock device 10 is unlocked by being detached from the engagement hole 11 of the lower rail 7.

  In this state, the vehicle seat 1 is moved back and forth to adjust the position, and when the operation member is released at a desired position, the main lock piece 12 and the sub-block piece 28 engage with the engagement hole 11 of the lower rail 7 and lock. Then, the vehicle seat 1 is fixed to a fixed position.

(Rear collision prediction operation mode)
When the prediction system S detects in advance a collision from behind by a radar or the like provided at a desired position of the vehicle body, the prediction system S sends a collision prediction signal, whereby the actuator 20 is activated and the actuator 25 of the actuator 20 is transmitted. The arm 24 is pushed and rotated, the transmission arm 24 rotates the mounting shaft 23 to rotate the arm 22, the arm 22 pulls the operating rod 17, and the operating rod 17 rotates the operating arm 16, The lock piece 12 is retracted from the engagement hole 11, and the lock device 10 is in an automatic unlock state.

  Even if the lock device 10 is automatically unlocked and the main lock piece 12 is retracted from the engagement hole 11, the sublock piece 28 is engaged with the engagement hole 11. The work sheet 1 is held (fixed) in a predetermined position by the lock device 10.

  Next, the sub-block piece 28 is engaged with the engagement hole 11 until the vehicle body 6 receives a rear collision and a load for backward movement is applied to the vehicle seat 1, but when the predetermined load is exceeded, the inclined surface 29 The sub-block piece 28 is retracted from the engagement hole 11 by being guided by. When the sub-block piece 28 is retracted from the engagement hole 11, the locking device 10 is completely unlocked, and the rearward movement of the vehicle seat 1 becomes free.

  When the rearward movement of the vehicle seat 1 is started, the engagement hook 47 provided on the vehicle seat 1 engages with the engagement groove 45 of the engagement moving body 46 connecting the piston rod 44 of the viscous damper 41. . Therefore, the engagement hook 47 moves backward together with the vehicle seat 1, and the engagement hook 47 moves the piston rod 44 backward via the engagement moving body 46.

  The piston rod 44 moves the piston 43 backward against the contact resistance with the viscous fluid or the viscous elastic body D in the cylinder 42, and the speed of the backward movement of the vehicle seat 1 by the resistance of the viscous fluid or the viscous elastic body D. To reduce the impact.

Therefore, the headrest 4 is provided so as to be pivotable in the front-rear direction by the link mechanism 50 with respect to the back seat 2 and configured to move forward using a load when the vehicle receives a rear collision. Therefore, the shock absorber 40 reduces the impact and rotates forward to support the head.
That is, the engagement hook 47 is predicted to have a rear collision by the prediction system S and engages with the engagement groove 45 of the engagement moving body 46 , and the engagement hook 47 is attached to the attachment shaft 23 to which the engagement hook 47 is attached. Since the engagement hook 47 engaged with the engagement groove 45 is immovable with respect to the vehicle seat 1, the outer periphery of the attachment shaft 23 is attached to the base of the arm 22 of the attachment shaft 23. It moves relatively until it contacts.

  Therefore, the wire 51 is relatively pulled by the engagement hook 47 to operate the link mechanism 50, and the headrest 4 rotates forward using the load when the vehicle receives a rear collision. Support the head.

  When the headrest 4 rotates forward, the engagement hook 47 comes into contact with the arm 22, and as described above, the load applied to the engagement hook 47 is engaged with the engagement moving body 46 that connects the piston rod 44 of the viscous damper 41. It is supported by the joint groove 45, and the speed of the rearward movement of the vehicle seat 1 is reduced by the movement resistance of the engagement moving body 46, thereby mitigating the impact.

  In this way, by releasing the lock of the slide rail 5 that supports the longitudinal load applied while the vehicle is running, the load caused by the inertia of the rear impact is attenuated by the shock absorber 40 and is seated in the locked state by the lock device 10. As a result, even if the vehicle seat 1 is moved rearward to absorb the load, the link mechanism 50 is interlocked with the shock absorber 40 so as to absorb the load. The headrest 4 that moves forward is securely supported.

  In this case, since the shock absorber 40 and the link mechanism 50 are configured to be linked by a wire 51, the other end of the wire 51 having one end connected to the link mechanism 50 is connected to the vehicle seat 1 and the shock absorber 40. What is necessary is just to connect in any path | route to the piston rod 44, and a structure is simple, and the front movement of the buffering device 40 and the headrest 4 interlock | operates reliably.

  In the embodiment, since the other end of the wire 51 is connected to the engagement hook 47, it is possible to easily configure the on / off operation of the forward movement of the viscous body damper 41 and the headrest 4 of the shock absorber 40.

  Since the engagement hook 47 is provided on the outer periphery of the attachment shaft 23 so as to be slidable between the arm 22 and the transmission arm 24, the slide lock releasing link mechanism 21 is attached to the engagement hook 47 and the stopper mechanism. Both can be used together, and a rational configuration can be achieved, further simplifying the configuration.

The side view of a sheet | seat. The perspective view of an upper rail. The perspective view of a lower rail. The disassembled perspective view of the lock piece of a locking device. FIG. Sectional drawing of a slide rail. Lock state diagram. Automatic unlock state diagram. The perspective view of an automatic unlocking mechanism part. The perspective view of a buffering device. The front schematic diagram. Block Diagram. The perspective view which shows an example of a headrest forward movement apparatus. The side view which shows an example of the connection structure of the wire which transmits operation to a headrest forward movement apparatus. The side view which shows the state which the headrest moved ahead.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle seat, 2 ... Back seat, 3 ... Seat seat, 4 ... Headrest, 5 ... Slide rail, 6 ... Vehicle body, 7 ... Lower rail, 8 ... Upper rail, 9 ... 9, 10 ... Locking device, 11 ... Engagement hole, 12 ... main lock piece, 13 ... operation lever, 14 ... shaft tube part, 15 ... rotation guide part, 16 ... operating arm, 17 ... operating rod, 18 ... long hole, 20 ... actuator, 21 ... slide lock Link mechanism for release, 22 ... arm, 23 ... mounting shaft, 24 ... transmission arm, 25 ... actuator, 26 ... bracket, 28 ... sub-block piece, 29 ... inclined surface, 30 ... sub-engaging claw, 35 ... engagement Holes, 40 ... shock absorbers, 41 ... viscous dampers, 42 ... cylinders, 43 ... pistons, 44 ... piston rods, 45 ... engagement grooves, 46 ... engagement moving bodies, 47 ... engagement hooks, 50 ... link mechanisms, 51 ... Wai Chromatography, 60 ... horizontal mounting shaft, 61 ... frame, 62 ... eccentric shaft portion, 63 ... pillar, 64 ... arm.

Claims (7)

A vehicle seat 1 is attached to a vehicle body 6 via a slide rail 5 so that the front and rear positions can be adjusted, and the locking device 10 of the slide rail 5 fixes the position of the vehicle seat 1 at a desired position in normal seat position adjustment. However, when a predetermined load is applied, the lock is automatically released and the rearward movement of the vehicle seat 1 is allowed, and the vehicle device when the lock device 10 is unlocked is configured. A shock absorber 40 that provides resistance to the backward movement of the seat 1 is provided, and the headrest 4 of the vehicle seat 1 is connected to the backward movement of the vehicle seat 1 when the vehicle receives a rear collision. A vehicle seat configured to move forward. A vehicle seat 1 is attached to a vehicle body 6 via a slide rail 5 so that the front and rear positions can be adjusted, and the locking device 10 of the slide rail 5 fixes the position of the vehicle seat 1 at a desired position in normal seat position adjustment. However, when a predetermined load is applied, the lock is automatically released and the rearward movement of the vehicle seat 1 is allowed, and the vehicle device when the lock device 10 is unlocked is configured. A shock absorber 40 that provides resistance to the backward movement of the seat 1 is provided, and the headrest 4 of the vehicle seat 1 transmits the backward movement of the vehicle seat 1 when the vehicle receives a rear collision by a wire 51. A vehicle seat configured to move the headrest 4 forward. In Claim 1 or Claim 2, the said buffering device 40 is provided between the said vehicle seat 1 and the said vehicle body 6, and the said headrest 4 is a horizontal axis in the front-back direction with the link mechanism 50 with respect to the said backrest seat 2. The link mechanism 50 transmits the rear movement of the vehicle seat 1 when the vehicle receives a rear collision to the headrest 4 via the wire 51 and interlocks with the rear movement of the vehicle seat 1. The vehicle seat is configured such that the headrest 4 rotates forward. 4. The shock absorber 40 according to claim 1, wherein the shock absorber 40 is configured such that the piston rod 44 of the viscous damper 41 does not give resistance to the back-and-forth movement of the vehicle seat 1 during normal seat position adjustment. A vehicle seat configured to be coupled to the slide rail 5 so as to give resistance to a backward movement of the vehicle seat 1 when a predetermined load is applied to the vehicle seat 1. In claim 1, claim 2, claim 3, or claim 4 , the shock absorber 40 has a plurality of engaging grooves 45 formed integrally or separately in the piston rod 44 of the viscous damper 41. An engagement moving body 46 is provided, and an engagement hook 47 for connecting / disconnecting to the engagement groove 45 is provided on the upper rail 8 of the slide rail 5 so as to be movable by a predetermined distance, and between the buffer device 40 and the link mechanism 50. A vehicle seat provided with a wire 51 for transmitting a load for operating the link mechanism 50. 6. The vehicle seat according to claim 5, wherein the engagement hook 47 is attached to the attachment shaft 23 so as to be rotatable and slidable by a predetermined distance, and a wire 51 connected to an end of the link mechanism 50 is connected to the engagement hook 47. . The transmission arm 24 and the arm 22 of the slide lock releasing link mechanism 21 are fixed to the attachment shaft 23 to which the engagement hook 47 is attached, and the arm 22 is connected to the lock piece 12 of the lock device 10. The lock piece 12 is connected so as to be retracted and rotated from the engagement hole 11, and the engagement hook 47 is slidably provided between the arm 22 of the mounting shaft 23 and the transmission arm 24. 22 and the transmission arm 24 are vehicle seats configured to also serve as a stopper mechanism for the engagement hook 47.

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