JP2009207771A - Rear seat device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily change in design of attitude angle and reclining operation of a reclining mechanism. <P>SOLUTION: A rear seat device includes: the reclining mechanism 12; and a seat back frame 112 to be bent in accordance with the movement of the reclining mechanism. The reclining mechanism includes a pair of link mechanisms 120 and 121 separately arranged in the upper and lower parts of a seat back. The two link mechanisms have structures different from each other. When the link mechanisms are in most extended states, distances between the leading-edge connection points 201 and 211 of the link mechanisms and the drive shafts 202 and 212 of the link mechanisms are different between the two link mechanisms. Besides, the extension/contraction strokes of the link mechanisms are different, or distances between the drive shafts and the leading-edge connection points are different between the most extended states and the most contracted states of the respective link mechanisms. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rear seat device for a vehicle, and more particularly to a rear seat device having a reclining mechanism capable of adjusting the position of a seat back.

  2. Description of the Related Art A rear seat device for an automobile has a reclining mechanism that adjusts the posture position of a seat back. The rear seat device includes a seat cushion having a seat surface on which an occupant is seated and a seat back on which the occupant leans back. In a typical rear seat device having a mechanism for adjusting the posture position of the seat back, the seat cushion slides forward and the seat back tilts backward by the operation of the occupant.

  In the rear seat device as described above, the seat back moves up and down in accordance with the change in the inclination angle. In addition, the seat back shape remains constant, and the whole seat tilts by rotating. For this reason, it was not optimal in terms of comfort in comfort. Alternatively, since the seat cushion slides back and forth, there is a problem that the space at the foot of the occupant is impaired. In view of this, a rear seat device has been proposed that enables a comfortable and comfortable posture by reducing the vertical movement and inclination change of the occupant during the movement of the seat back (see, for example, Patent Document 1).

  The reclining mechanism of the rear seat device disclosed in Patent Document 1 includes a link mechanism that moves the seat back, and the link mechanism includes a parallel link mechanism. The parallel link mechanism can operate to move the upper body of the occupant in a substantially horizontal direction without moving up and down. Specifically, the seat back portion has a frame bent at the center, and the link mechanism is connected to the upper frame on the upper side.

The link mechanism has a parallelogram parallel link mechanism. Each vertex of the parallel link mechanism serves as a pivot, and each link constituting the parallel link mechanism rotates in operation. When the parallel link is deformed, the frame is bent and the upper frame moves substantially in parallel. As a result, the occupant's vertical movement and change in inclination are reduced, and a comfortable and comfortable posture is made possible.
JP 2003-180476 A

  The seat device proposed by Patent Document 1 is excellent in improving the comfort of the passenger's comfort posture. However, the posture angle of the seat back and the posture variable range of the reclining mechanism are required to be changed according to the type of vehicle on which the rear seat device is mounted and the user's request. In the reclining device disclosed in Patent Document 1, two parallel link mechanisms are mounted on the left and right sides of the seat back. For this reason, in order to change the posture angle of the seatback and the posture variable range of the reclining mechanism, the operation of the link mechanism must be redesigned to be different from the parallel operation.

  In a complicated link mechanism such as the parallel link mechanism disclosed in Patent Document 1, a large change in the design requires a lot of time for new design and manufacture. Accordingly, there is a need for a rear seat device that can easily change the design of the posture angle of the seat back and the posture variable range of the reclining mechanism according to the type of vehicle and the user's request.

  One aspect of the present invention is a rear seat device having a seat back structure in which an upper frame and a lower frame are rotatably connected to each other. The rear seat device is spaced apart in the vertical direction of the seat back, and is mounted on the upper frame. A pair of link mechanisms are connected and move the upper frame back and forth. Each of the pair of link mechanisms includes a drive shaft fixed to the base, one end portion rotatably connected to the drive shaft, and the other end portion rotatably connected to the upper frame. Arm. Between the pair of link mechanisms, the distance from the drive shaft in the most extended state to the connection point of the link mechanism is different. In a preferred example, the expansion / contraction stroke is further different between the pair of link mechanisms. Alternatively, the distance from the drive shaft in the most contracted state to the most connecting point of the link mechanism is different between the pair of link mechanisms. As a result, it is possible to easily change the design of the posture angle of the seatback and the posture variable range of the reclining mechanism.

  Each of the pair of link mechanisms preferably further includes a fixing bracket that is fixed to the base and that rotatably fixes the arm at an intermediate portion of the arm. Thereby, the play of an arm can be decreased and operation | movement can be stabilized. In a preferred example, the length of the arm is different between the pair of link mechanisms. Thereby, the design of the link mechanism can be easily changed.

  In a preferred example, each of the pair of link mechanisms further includes a secondary arm that connects the arm and the upper frame, and the other end of the arm is connected to one end of the secondary arm. The other end of the secondary arm is rotatably connected to the upper frame. The pair of link mechanisms have different numbers of arms connected to each other. Thereby, the design change of a link mechanism can be performed more easily.

  According to the present invention, it is possible to realize a rear seat device that can easily change the design of the posture angle of the seat back and the posture variable range of the reclining mechanism.

  Embodiments to which the present invention is applied will be described below. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. Moreover, in each drawing, the same code | symbol is attached | subjected to the same element and the duplication description is abbreviate | omitted as needed. The rear seat device of the present embodiment includes a reclining mechanism and a seat back frame that bends in accordance with the movement of the reclining mechanism. The reclining mechanism has a pair of link mechanisms that are spaced apart above and below the seat back. The two link mechanisms are fixed to the vehicle body and connected to the upper frame of the seat back frame.

  The two link mechanisms of the present embodiment have different structures, and further, in the most extended state, the distance between the most advanced connection point of the link mechanism and the vehicle body side fixed drive shaft of the link mechanism is two links. It is different between mechanisms. As a more specific aspect, for example, the two link mechanisms have different expansion / contraction strokes. Alternatively, the distance between the drive shaft and the foremost connection point is different between the two link mechanisms in the most extended state and the most contracted state. Alternatively, the two link mechanisms have different strokes, and the distance between the drive shaft and the most distal connection point is different between the two link mechanisms in the most extended state and the most contracted state. Since the two link mechanisms have such different structures, it is possible to easily change the design of the attitude angle and the reclining operation of the reclining mechanism.

  FIG. 1 schematically shows a partial configuration of a vehicle rear seat device 1 according to the present embodiment. The rear seat device 1 includes a seat cushion (not shown) having a seat surface on which an occupant is seated, and a seat back 11 that is a backrest portion on which the occupant in the seated state leans back. The rear seat device 1 of this embodiment has a reclining mechanism (not shown), and as shown in FIG. 1, the seat back 11 is moved in the front-rear direction, and its posture position is adjusted. In FIG. 1, a partial configuration of the seat back 11 is shown, and a headrest 111 and a seat back frame 112 as a framework for supporting the entire seat back 11 are shown. In addition to these, the seat back 11 has a pad provided on the outer periphery of the seat back frame 112 and a cover that covers the surface of the pad.

  FIG. 1 shows two different states of the seat back 11. In the first state, which is a neutral state, the seat back 11 is located in the foremost position and is not in a so-called comfort posture. In another second state, the seat back 11 is moved rearward from the first state, and is in a so-called comfort posture state. In FIG. 1, the occupant is in the first state, and only the seat back 11 is shown in two states, the first state and the second state. In this specification, the seat surface side of the seat back 11 is defined as the front side, and the opposite side is defined as the rear side. The seat cushion side is the lower side and the headrest 111 side is the upper side. This corresponds to the front-rear and vertical directions of the vehicle body.

  The seat back frame 112 has a lower lower frame 113 and an upper upper frame 114. The lower end of the lower frame 113 is connected to the fixed bracket 117 by a bolt 116. The bolt 116 is fixed to the fixed bracket 117, and the bracket 117 is fixed to the vehicle body. The lower frame 113 can rotate around the bolt 116. The lower frame 113 and the upper frame 114 are connected via a bolt 115, and the seat back frame 112 can be bent with the bolt 115 as an axis.

  The upper frame 114 moves in the front-rear direction according to the operation of the reclining mechanism. As the upper frame 114 moves, the lower frame 113 rotates about the bolt 116 and rotates about the bolt 115 at the upper end. The seat back frame 112 bends in the front-rear direction around the bolt 115 as the posture position of the seat back 11 changes. Specifically, the seat back frame 112 bends forward.

  FIG. 2 is a perspective view showing a connection state between the seat back frame 112 and the reclining mechanism 12. The reclining mechanism 12 has an upper link mechanism 120 on the upper side and a lower link mechanism 121 on the lower side, which are fixed to the base 124. The upper link mechanism 120 and the lower link mechanism 121 are connected to the upper frame 114 via a link bracket 122 that is a part of the reclining mechanism 12. As the upper link mechanism 120 and the lower link mechanism 121 expand and contract, the upper frame 114 moves back and forth. The movement direction of the upper frame 114 is the same as the expansion / contraction direction of the upper link mechanism 120 and the lower link mechanism 121.

  The lower frame 113 rotates around the bolt 116 and also rotates around the bolt 115. As the upper link mechanism 120 and the lower link mechanism 121 contract, the seat back frame 112 bends about the bolt 115 as an axis. By bending the seat back frame 112 in accordance with the posture change of the seat back 11, it is possible to provide a comfortable and comfortable posture by reducing fluctuations in the vertical position and inclination of the occupant. The seat back frame 112 has a U-shaped lower frame 113 having three sides and an upper frame 114 having the same shape. These are rotatably connected by two bolts 115 to form a rectangular seat back frame 112. The coupling bracket 123 is welded to the upper side of the upper frame 114 and further fixed to the link bracket 122. The upper frame 114 is fixed to the link bracket 122 by a support bar 128 on the lower end side.

  FIGS. 3A and 3B are perspective views showing the operation of the seat back frame 112 and the reclining mechanism 12. FIG. 3A shows the reclining mechanism 12 and the seat back frame 112 in the neutral state, and FIG. 3B shows the reclining mechanism 12 and the seat back frame 112 in the reclining state. In the neutral state shown in FIG. 3A, the reclining mechanism 12 is in the most extended state. Further, in the reclining state of FIG. 3B, the reclining mechanism 12 is in the most contracted state. The state of the seat back frame 112 and the reclining mechanism 12 changes continuously or stepwise between the state of FIG. 3A and the state of FIG.

  The upper link mechanism 120 is connected to the upper bar 221 of the link bracket 122 at a connecting point 201 at the tip thereof. More specifically, the connection point 201 is connected to the upper bar 221 via the bracket 223. The lower link mechanism 121 is directly connected to the lower bar 222 of the link bracket 122 at a connecting point 211 at the tip thereof. The connection point 201 and the connection point 211 are the most advanced connection points of the upper link mechanism 120 and the lower link mechanism 121, respectively.

  Each of the upper link mechanism 120 and the lower link mechanism 121 includes an upper drive shaft 202 and a lower drive shaft 212. The axial directions of the upper drive shaft 202 and the lower drive shaft 212 are perpendicular to the expansion / contraction directions of the upper link mechanism 120 and the lower link mechanism 121. Further, the upper drive shaft 202 and the lower drive shaft 212 are fixed with respect to the vehicle body and do not move.

  FIGS. 4A and 4B are side views showing the operations of the seat back frame 112 and the reclining mechanism 12, and correspond to FIGS. 3A and 3B, respectively. Specifically, FIG. 4A shows the reclining mechanism 12 and the seat back frame 112 in the neutral state, and FIG. 4B shows the reclining mechanism 12 and the seat back frame 112 in the reclining state. ing. Details of the link mechanisms 120 and 121 will be described later.

  In the neutral state of FIG. 4A, the distance L0u between the front end connection point 201 of the upper link mechanism 120 and the upper drive shaft 202 is the distance between the front end connection point 211 of the lower link mechanism 121 and the lower drive shaft 212. It is shorter than the distance L01. Similarly, in the reclining state of FIG. 4B, the distance L1u between the front end connection point 201 of the upper link mechanism 120 and the upper drive shaft 202 is equal to the front end connection point 211 of the lower link mechanism 121 and the lower drive shaft 212. Shorter than the distance L1l.

  FIGS. 5A and 5B are perspective views showing the structure of the reclining mechanism 12, and correspond to FIGS. 3A and 3B, respectively. FIG. 5A shows the reclining mechanism 12 in the neutral state, and FIG. 5B shows the reclining mechanism 12 in the reclining state. The reclining mechanism 12 has a base 124 on the rear side, and the base 124 is firmly fixed to the vehicle body with bolts. Each of the upper drive shaft 202 and the lower drive shaft 212 is connected to the base 124 via a bracket. The upper drive shaft 202 and the lower drive shaft 212 are cylindrical shafts extending in the left-right direction.

  As described above, the upper link mechanism 120 and the lower link mechanism 121 have different structures from each other, and in the most extended state (FIG. 5A) and the most contracted state (FIG. 5B), The distances between the connection points 201 and 211 and the drive shafts 202 and 212 are different. The structures of the link mechanisms 120 and 121 will be described with reference to FIGS.

  The upper link mechanism 120 includes a drive shaft 202 that is fixed to the base 124 and extends in the left-right direction, and two primary arms that are rotatably connected to the drive shaft 202. An upper upper primary arm 203a and a lower lower primary arm 203b. Each of the primary arms 203a and 203b has one end rotatably connected to the drive shaft 202, and the other end connected to a straight plate-like secondary arm 204a and 204b (see FIG. 4). Yes.

  The positions of the primary arms 203a and 203b are shifted in the vertical direction. The upper primary arm 203a is on the upper side of the drive shaft 202, and the lower primary arm 203b is on the lower side of the drive shaft 202. The secondary arms 204a and 204b are rotatably connected to the primary arms 203a and 203b on rotation shafts 205a and 205b (see FIG. 4), respectively. The secondary arms 204 a and 204 b are connected to the upper bar 221 through the bracket 223. Connection points 201 a and 201 b (see FIG. 4) between the secondary arms 204 a and 204 b and the bracket 223 are the most advanced connection points of the upper link mechanism 120. As such, the primary arms 203a, 203b are indirectly coupled to the upper frame 114 via the secondary arms 204a, 204b (and other components).

  The primary arms 203a and 203b are L-shaped, and the concave portions (inner sides) face each other. The primary arms 203a and 203b are connected to the drive shaft 202 via rotation shafts 206a and 206b, respectively. It is also important to note that the primary arms 203a and 203b are connected to the fixed rotation shafts 207a and 207b in the middle thereof, and the fixed rotation shafts 207a and 207b are fixed to the base 124 by brackets. ing.

  Fixed rotation shafts 207 a and 207 b extending vertically are parallel to each other and perpendicular to the drive shaft 202. The primary arms 203a and 203b rotate on the rotation shafts 206a and 206b and rotate on the fixed rotation shafts 207a and 207b. In addition, the strength of the reclining mechanism 12 can be increased by sharing the fixed rotation shafts 207a and 207b between the upper and lower two link mechanisms 120 and 121.

  The link mechanism 120 performs an expansion / contraction operation between the most extended state in FIG. 5A and the most contracted state in FIG. The drive shaft 202 is a lead screw shaft, and the rotation shafts 206a and 206b are connected to the drive shaft 202 via lead nuts. When the link mechanism 120 contracts, the rotation shafts 206a and 206b move away from each other, and when the link mechanism 120 extends, the rotation shafts 206a and 206b move toward each other.

  The primary arms 203a and 203b are rotatably fixed to the fixed rotation shafts 207a and 207b, respectively. The fixed rotation shafts 207a and 207b are shafts that perform free rotation, but they are fixed to the base 124 and do not move their positions when the link mechanism 120 expands and contracts. The primary arms 203a and 203b rotate around the fixed rotation shafts 207a and 207b when the rotation shafts 206a and 206b move on the drive shaft 202. The rotating shafts 206a and 206b are freely rotating shafts, and the primary arms 203a and 203b rotate on the rotating shafts 206a and 206b according to the movement of the rotating shafts 206a and 206b.

  In the contraction operation, when the rotation shafts 206a and 206b move linearly in directions away from each other, the upper primary arm 203a and the lower primary arm 203b rotate to the drive shaft 202 side. The rotation directions of the upper primary arm 203a and the lower primary arm 203b are opposite to each other. The direction in which the respective rotation shafts 206a, 206b of the primary arms 203a, 203b move is opposite to the direction in which the respective primary arms 203a, 203b rotate. The operation of each part in the decompression operation is reversed.

  The upper frame 114 moves back and forth according to the movement of the secondary arms 204a and 204b. When the secondary arms 204a and 204b move, the secondary arms 204a and 204b rotate on the rotating shafts 205a and 205b on the primary arm 203a and 203b side, and also indirectly connect to the upper bar 221. It rotates at 201b. The connection points 201 a and 201 b are fixed to the upper bar 221. The rotation directions of the secondary 204a and 204b on the rotation shafts 205a and 205b are opposite to the upper primary arms 203a and 203b to which the secondary 204a and 204b are connected. The rotation axes of the secondary arms 204a and 204b are all axes that rotate freely. As described above, the left and right arm assemblies of the primary arms 203a and 203b and the secondary arms 204a and 204b have symmetrical shapes and operations.

  Since the upper link mechanism 120 has such a structure, the structure of the link mechanism 120 can be made simple and compact with a small number of parts. Further, since the primary arms 203a and 203b rotate around the fixed rotation shafts 207a and 207b, there is little backlash in the operations of the primary arms 203a and 203b, and a stable reclining operation can be realized.

  The lower link mechanism 121 has a structure similar to the upper link mechanism 120. Hereinafter, differences from the upper link mechanism 120 in the structure of the lower link mechanism 121 will be mainly described. The lower link mechanism 121 includes a drive shaft 212 that is fixed to the base 124 and extends in the left-right direction, and two primary arms 213a and 213b that are rotatably connected to the drive shaft 212. The primary arms 213a and 213b of the lower link mechanism 121 have substantially the same structure as the primary arms 203a and 203b of the upper link mechanism 120, and the dimensions beyond the fixed rotation shafts 207a and 207b are the upper link mechanism. 120 is longer than the primary arms 203a and 203b. In the neutral state shown in FIG. 5A, the primary arms 213a and 213b cross each other.

  In the contraction operation, when the rotation shafts 216a and 216b move linearly in directions away from each other, the primary arms 213a and 213a rotate toward the drive shaft 212. The rotation directions of the upper primary arm 213a and the lower primary arm 213b are opposite to each other. Secondary arms 214a and 214b are connected to rotation shafts 215a and 215b at the tips of the primary arms 213a and 213a.

  The secondary arms 214a and 214b are connected to the tertiary arm 219 at the rotation shafts 218a and 218b at the tips thereof. In the expansion / contraction operation of the lower link mechanism 121, the secondary arms 214a and 214b rotate on the rotation shafts 215a and 215b and the rotation shafts 218a and 218b. The tertiary arm 219 has a Z shape and connects the secondary arms 214a and 214b at different positions in the vertical direction. Further, the tertiary arm 219 is connected to the quaternary arm 220 at the center thereof. The connection point between the quaternary arm 220 and the lower bar 222 is the most advanced connection point 211 of the lower link mechanism 121. In this example, the quaternary arm 220 is fixed to the lower bar 222. In this manner, the primary arms 213a and 213a are indirectly connected to the upper frame 114 via other components.

  The link mechanisms 120 and 121 have a plurality of arms. In the two link mechanisms having the link mechanism structure of this embodiment, the posture angle and the reclining operation of the reclining mechanism 12 can be adjusted by changing some structural elements in the design. In the preferred example, the link mechanisms 120 and 121 have different numbers of arms. Thereby, in the most extended state (neutral state) and the most contracted state, the most advanced connection points 201 and 211 of the link mechanisms 120 and 121 are at different distances from the drive shafts 202 and 212.

  In another preferred method, the arms of the link mechanisms 120, 121 have different shapes. Specifically, the dimensions of the primary arms 203a, 203a, 213a, 213a or the secondary arms 204a, 204b, 214a, 214b and / or the angles of the L-shaped primary arms 203a, 203a, 213a, 213a are changed. By doing so, the distance between the tip connection points 201 and 211 and the drive shafts 202 and 212 in the most extended state can be made different. At this time, the distance between the tip connection points 201 and 211 and the drive shafts 202 and 212 in the most contracted state is different and / or the strokes of the link mechanisms 120 and 121 are different.

  In a preferred example, the angle of the triangle formed by the three connecting points of the primary arms 203a, 203a, 213a, and 213a is adjusted. For example, the expansion / contraction strokes of the two upper and lower link mechanisms can be adjusted by adjusting the angles at the fixed rotation connection points 207a, 207b, 207a, and 207b. Specifically, the positions of the rotation shafts 205a, 205b, 215a, and 215b connected to the rotation shafts 206a, 206b, 216a, and 216b on the drive shafts 202 and 212 or the secondary arms 204a, 204b, 214a, and 214b, By adjusting the fixed rotation connection points 207a, 207b, 207a, and 207b, the expansion strokes of the two upper and lower link mechanisms or the positions of the front end connection points 201 and 211 can be adjusted.

  Alternatively, the design of the reclining mechanism can be changed by changing the shape of the secondary arms 204a, 204b, 214a, 214b. Specifically, the dimensions of the secondary arms 204 a, 204 b, 214 a, 214 b, that is, the distance between the rotating shafts at both ends thereof are set to different values between the vertical link mechanisms 120, 121. Thereby, the space | interval of the drive shafts 202 and 212 and the most advanced connection points 201 and 211 in the most extended state and the most contracted state can be made different. It is also effective to change the dimensions of both the primary arms 203a, 203a, 213a, 213a and the secondary arms 204a, 204b, 214a, 214b.

  Alternatively, the movement distances of the rotation shafts 206a, 206b, 216a, and 216b on the drive shafts 202 and 212 are changed to adjust the rotation angles of the primary arms 203a, 203a, 213a, and 213a. Accordingly, it is possible to realize different expansion / contraction strokes between the link mechanisms 120 and 121. Alternatively, the positions of the rotation shafts 206a, 206b, 216a, and 216b on the drive shafts 202 and 212 in the most extended state and the most contracted state are different between the two link mechanisms 120 and 121.

  As a result, the distance between the drive shafts 202 and 212 and the foremost connection points 201 and 211 in the most extended state and the most contracted state is made different between the two link mechanisms 120 and 121 with the same expansion / contraction stroke. Can do. In this way, the design adjustment of the reclining mechanism 12 can be performed by setting different movement ranges (including positions and distances) of the rotation shafts 206a, 206b, 216a, 216b on the drive shafts 202, 212 for each link mechanism. Can be easily performed.

  As mentioned above, although this invention was demonstrated taking preferable embodiment as an example, this invention is not limited to said embodiment. A person skilled in the art can easily change, add, and convert each element of the above-described embodiment within the scope of the present invention. The two link mechanisms are configured such that one link mechanism and the other link mechanism have different ones of the upper arm and the lower arm as long as the seat back portion can be driven reliably. May be.

  As described above, the drive shaft for driving the drive motor and the link mechanism is preferably fixed to the vehicle main body side, but fixing this to the seat device by design is not excluded. Further, the arm may be directly connected to the upper frame without using a member such as a link bracket.

It is a figure which shows typically a partial structure of the vehicle seat apparatus which concerns on embodiment of this invention. It is a perspective view which shows the connection state of the seat back frame and reclining mechanism which concern on embodiment of this invention. It is a perspective view which shows operation | movement of the seat back frame and reclining mechanism which concern on embodiment of this invention. It is a side view which shows operation | movement of the seat back frame and reclining mechanism which concern on embodiment of this invention. It is a perspective view which shows the structure of the reclining mechanism which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rear seat apparatus, 11 Seat back, 12 Reclining mechanism 111 Headrest, 112 Seat back frame, 113 Lower frame 114 Upper frame, 115 bolt, 116 bolt, 117 Fixed bracket 120 Upper link mechanism, 121 Lower link mechanism, 122 Link bracket 123 Connection Bracket, 124 Base, 128 Support bar, 201 Most advanced connection point 202 Upper drive shaft, 203a, 203b Primary arm 204a, 204b Secondary arm, 205a, 205b Rotation shaft 206a, 206b Rotation shaft, 207a, 207b Fixed rotation Shaft 211 Tip connection point, 212 Lower drive shaft, 213a, 203b Primary arm 214a, 214b Secondary arm, 215a, 215b Rotating shaft 216a, 216b Rotating shaft, 218a 218b pivot shaft, 219 tertiary arm 220 quaternary arm 221 Upper Bar, 222 Roaba, 223 bracket

Claims (7)

In a rear seat device having a seat back structure in which an upper frame and a lower frame are rotatably connected,
The seat back is spaced apart in the vertical direction, connected to the upper frame, and has a pair of link mechanisms that move the upper frame back and forth,
Each of the pair of link mechanisms is
A drive shaft fixed to the base;
An arm having one end rotatably connected to the drive shaft and the other end rotatably connected to the upper frame;
Between the pair of link mechanisms, the distance from the drive shaft in the most extended state to the connection point of the most advanced link mechanism is different.
A rear seat device characterized by that. The expansion / contraction stroke is further different between the pair of link mechanisms,
The rear seat device according to claim 1. Between the pair of link mechanisms, the distance from the drive shaft in the most contracted state to the most advanced connection point of the link mechanism is different,
The rear seat device according to claim 1, wherein the rear seat device is provided. Each of the pair of link mechanisms is further fixed to the base, and further includes a fixing bracket that rotatably fixes the arm at an intermediate portion of the arm. The rear seat device described. The length of the arm is different between the pair of link mechanisms,
The rear seat device according to claim 4. Each of the pair of link mechanisms further includes a secondary arm that connects the arm and the upper frame,
The other end of the arm is rotatably connected to one end of the secondary arm,
The other end of the secondary arm is rotatably connected to the upper frame.
The rear seat device according to any one of claims 1 to 5. The pair of link mechanisms have different numbers of arms connected to each other,
The rear seat device according to any one of claims 1 to 6.

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