Operation assisting structure for vehicle seat

Abstract

To enhance flexibility of the arrangement of a spring in a structure for assisting a switching operation between a seating accepted state and a seating inhibited state of a vehicle seat by energizing force of the spring.SOLUTION: An operation assisting structure for a vehicle seat includes: a hinge bracket 44 where a long hole 52 is formed; a seat back frame 24R rotating relatively to the hinge bracket 44; and a torsion bar 54 in which a base end part is fixed to the seat back frame 24R, and a tip end part 54C is inserted in the long hole 52. When a vehicle seat is operated to switch from a seating inhibited state to a seating accepted state, the torsion bar 54 is twisted in one direction about an axis line as the tip end part 54C engages one end part of the long hole 52. When the vehicle seat is operated to switch from the seating accepted state to the seating inhibited state, the torsion bar 54 is twisted in the other direction about the axis line as the tip end part 54C engages the other end part of the long hole 52.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle seat, and more particularly to an operation assist structure that assists in switching a vehicle seat between a seatable state and an unseatable state. [Background technology]

[0002] The vehicle seat disclosed in Patent Document 1 listed below is equipped with a torsion spring (torsion coil spring) that applies elastic force in the rotational direction to two members (a cushion frame and a link) that rotate relatively in both forward and reverse directions depending on the operating direction when switching the seat from one state to the other, either a seatable state or an unseatable state. This torsion coil spring is maintained in a state where a restoring elastic force is stored in a direction that assists the relative rotation of the two members when the seat is in either the seatable state or the unseatable state, and is configured so that the direction of the restoring elastic force stored in the torsion coil spring switches midway through the relative rotation of the two members associated with the seat switching operation. This assists the operating force in both directions when switching the seat from the seatable state to the unseatable state without incurring an increase in cost or mass, thereby improving the operating feel.

[0003] The vehicle seat reversing mechanism disclosed in Patent Document 2 listed below has a seat mounted on a support shaft that can be reversed and pivoted between a use position and a storage position, and includes a spare shaft separate from the support shaft that is arranged coaxially with the support shaft, and a torsion coil spring fitted onto the spare shaft to form a force storage mechanism that accumulates a biasing force that urges the seat to swing toward the storage position as the seat is pivoted to the use position, thereby improving operability when pivoting the seat between the use position and the storage position effectively regardless of the operation direction while improving the durability of the torsion coil spring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-80935 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-19505 Summary of the Invention [Problem to be solved by the invention]

[0005] In the prior art disclosed in Patent Document 1, a torsion coil spring is fitted onto the outside of a hinge pin that serves as the center of relative rotation between the cushion frame and the link. Similarly, in the prior art disclosed in Patent Document 2, a torsion coil spring is fitted onto the outside of an auxiliary shaft that is disposed coaxially with the support shaft that serves as the center of rotation of the seat. As such, since the torsion coil spring needs to be disposed at the center of rotation of the object to be biased, there is room for improvement in terms of increasing the degree of freedom in spring placement.

[0006] The present invention aims to provide an operation assist structure for a vehicle seat that can improve the freedom of spring placement in a configuration in which the switching operation of a vehicle seat between a seatable state and an unseated state is assisted by the spring force. [Means for solving the problem]

[0007] The first aspect of the vehicle seat operation assist structure is an operation assist structure for a vehicle seat that is provided on a vehicle seat that can be switched between a seatable state where an occupant can be seated and an unseatable state where an occupant cannot be seated, and includes a first member having a long hole formed therein, a second member that rotates relative to the first member by the switching operation, and a torsion bar whose base end is fixed to the second member and whose tip end is inserted into the long hole, and whose tip end engages with one end of the long hole and twists in one direction about the axis when switching from the unseatable state to the seatable state, and whose tip end engages with the other end of the long hole and twists in the other direction about the axis when switching from the seatable state to the unseatable state.

[0008] According to a first aspect, a vehicle seat that can be switched between a seatable state where an occupant can be seated and an unseating state where an occupant cannot be seated rotates a first member and a second member relative to each other by the switching operation. An elongated hole is formed in the first member, and a base end of a torsion bar is fixed to the second member. The tip end of the torsion bar is inserted into the elongated hole of the first member. When the vehicle seat is switched from the unseating state to the seatable state, the tip end of the torsion bar engages with one end of the elongated hole and is twisted in one direction about the axis. This allows the switching operation of the vehicle seat from the seatable state to the unseating state to be assisted by the biasing force of the torsion bar. Furthermore, when the vehicle seat is switched from the seatable state to the unseating state, the tip end of the torsion bar engages with the other end of the elongated hole and is twisted in the other direction about the axis. This allows the operation of switching the vehicle seat from an unseating state to a seating state to be assisted by the biasing force of the torsion bar. Moreover, since there is no need to place a torsion bar (i.e., a torsion bar spring) at the center of relative rotation between the first and second members, the degree of freedom in spring placement can be improved.

[0009] The second aspect of the operation assist structure for a vehicle seat is the first aspect, in which one of the first member and the second member is a hinge bracket attached to the seat cushion frame of the vehicle seat or the vehicle body, and the other of the first member and the second member is a seat back frame of the vehicle seat.

[0010] In the second aspect of the vehicle seat operation assist structure, the seatback frame rotates relative to the seat cushion frame of the vehicle seat or a hinge bracket attached to the vehicle body. This allows the seatback to be switched between, for example, an upright seating state and a forward-tilted, non-seating state. The forward-tilting and raising operations of the seatback can be assisted by the biasing force of the torsion bar.

[0011] The third aspect of the operation assist structure for a vehicle seat is the first or second aspect, wherein the second member has a support portion that supports the intermediate portion between the base end and the tip end of the torsion bar in a torsionally deformable manner.

[0012] In the operation assist structure for a vehicle seat of the third aspect, the middle portion of the torsion bar is supported by the support portion provided on the second member so as to be torsionally deformable, thereby stabilizing the torsional deformation of the torsion bar.

[0013] The fourth aspect of the operation assist structure for a vehicle seat is any one of the first to third aspects, in which a resin member made of resin is provided at one end and the other end of the long hole, against which the tip of the torsion bar comes into contact during the switching operation.

[0014] According to the fourth aspect of the vehicle seat operation assist structure, when switching the vehicle seat between a seatable state and an unseatable state, the tip of the torsion bar comes into contact with the resin members provided at one end and the other end of the elongated hole of the first member, which makes it easier to prevent point contact and ensure durability compared to a configuration in which the tip of the torsion bar comes into direct contact with the one end and the other end of the elongated hole, for example.

[0015] The fifth aspect of the vehicle seat operation assist structure is any one of the first to fourth aspects, and has a hole formed therein into which the tip end of the torsion bar is inserted, and has a retaining member attached to the first member so as to be slidable along the long hole.

[0016] In the fifth aspect of the vehicle seat operation assist structure, when switching the vehicle seat between a seatable state and an unseatable state, a retaining member having a hole into which the tip of the torsion bar is inserted slides along the elongated hole of the first member, and this retaining member can prevent the tip of the torsion bar from accidentally coming out of the elongated hole. [Effects of the Invention]

[0017] As described above, the operation assist structure for a vehicle seat according to the present invention can improve the freedom of spring arrangement in a configuration in which the spring force assists the operation of switching the vehicle seat between a seatable state and an unseated state. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a side view showing a vehicle seat to which an operation assist structure for a vehicle seat according to an embodiment is applied; [Figure 2] FIG. 2 is a perspective view showing a seat back frame and a hinge bracket. [Figure 3] FIG. 3 is an enlarged perspective view of a part of FIG. 2. [Figure 4] FIG. [Figure 5] FIG. 10 is a side view for explaining assistance in tilting and raising the seat back forward. [Figure 6] FIG. 4 is a perspective view corresponding to FIG. 3, illustrating a state in which the seat back is in an upright position. [Figure 7] FIG. 4 is a perspective view corresponding to FIG. 3, illustrating a state in which the seat back is positioned at a forward-tilting assistance end position. [Figure 8] FIG. 4 is a perspective view corresponding to FIG. 3, illustrating a state in which the seat back is raised and positioned at an assist end position. [Figure 9] FIG. 4 is a perspective view corresponding to FIG. 3, illustrating a state in which the seat back is in a forward-folded position. [Figure 10] FIG. 10 is a perspective view showing a modified example in which a support portion for the torsion bar is provided. [Figure 11] FIG. 10 is a perspective view showing a modified example in which a resin member is attached to the hinge bracket. [Figure 12] FIG. 10 is a perspective view showing a modified example in which a support portion and a retaining member for the torsion bar are provided. [Figure 13] FIG. 4 is a cross-sectional view showing the configuration of the periphery of the retaining member. [Figure 14] FIG. 13 is a perspective view corresponding to FIG. 12, illustrating a state in which the seat back is in an upright position. [Figure 15] FIG. 13 is a perspective view corresponding to FIG. 12, illustrating a state in which the seat back is positioned in a forward-folding position. [Figure 16] FIG. 10 is a perspective view showing a modified example in which the base end of the torsion bar is prevented from coming off. [Figure 17] FIG. 10 is a perspective view showing a modified example in which the torsional deformation portion of the torsion bar is arranged coaxially with the rotation center of the seat back. DETAILED DESCRIPTION OF THE INVENTION

[0019] An operation assist structure for a vehicle seat according to one embodiment of the present invention (hereinafter simply referred to as "operation assist structure") will be described below with reference to Figures 1 to 9. Note that in each figure, some reference numerals may be omitted to make the drawings easier to read. Arrows FR, LH, and UP, which are appropriately depicted in each figure, respectively indicate the front, left, and top of a vehicle seat 10 to which the operation assist structure according to this embodiment is applied. Hereinafter, when the front-rear, left-right, top-bottom directions are used in the description, they will indicate directions relative to the vehicle seat 10.

[0020] As shown in Fig. 1, a vehicle seat 10 to which the operation assist structure according to this embodiment is applied is a split-folding rear seat for three passengers, and includes a seat cushion 12 on which passengers sit, a seat back 14 that supports the passengers' backs, and three headrests 16 that support the passengers' heads. The seat back 14 is divided into a right seat back 14R for two passengers and a left seat back 14L for one passenger. The left and right seat backs 14L, 14R are rotatably attached to a vehicle body (not shown) and can be folded forward onto the seat cushion 12.

[0021] The left and right seatbacks 14R, 14L are each provided with a locking device 18 for restraining the left and right seatbacks 14R, 14L against the side of the vehicle body (not shown) in an upright position (the position shown in FIG. 1; hereinafter referred to as the "upright position"). The locking device 18 has a locking body 20 provided on the outer side of the left and right seatbacks 14R, 14L in the left-right direction, and an operating lever 22 provided on the outer shoulder of the left and right seatbacks 14R, 14L in the left-right direction.

[0022] The lock body 20 has a latch (not shown) that engages with a striker (not shown) provided on the side of the vehicle body. This engagement restrains the left and right seatbacks 14R, 14L in the upright position. This engagement is released by operating the operating lever 22. This allows the seatbacks 14L, 14R to be tilted forward. When the left and right seatbacks 14L, 14R are in the upright position, the vehicle seat 10 is in a seatable state where an occupant can be seated, and when the left and right seatbacks 14L, 14R are tilted forward, the vehicle seat 10 is in an unseating state where an occupant cannot be seated. In other words, the vehicle seat 10 is switchable between a seatable state and an unseating state. Hereinafter, when the directions of front, rear, left, right, up, and down are used in the description, these directions refer to the state when the seatback 14R is in the upright position, unless otherwise specified.

[0023] As shown in Fig. 2, the left and right seat backs 14L, 14R include seat back frames 24L, 24R (see Fig. 2) that are frames. Seat back pads 26L, 26R (see Fig. 1) that are cushioning materials are attached to the seat back frames 24L, 24R, and trim covers 28L, 28R (see Fig. 1) that are upholstery are covered on the seat back pads 26L, 26R. The seat back frames 24L, 24R are made of press-molded metal plate material or metal pipe material, the seat back pads 26L, 26R are made of foam such as urethane foam, and the trim covers 28L, 28R are formed into a bag shape by sewing together a plurality of upholstery pieces made of, for example, cloth, leather, synthetic leather, or the like.

[0024] The seatback frames 24L, 24R include frame main bodies 30L, 30R made of metal pipe material and back panels 32L, 32R made of press-formed metal plates. The frame main bodies 30L, 30R have a generally rectangular frame shape when viewed from the front-to-rear direction. The back panels 32L, 32R have a generally rectangular plate shape when viewed from the front-to-rear direction and are disposed rearward of the frame main bodies 30L, 30R. The back panels 32L, 32R are fixed to the frame main bodies 30L, 30R by welding or other means.

[0025] The right seatback frame 24R corresponds to the "second member" in the present invention. Hinge mounting portions 34, 36 made of press-formed metal plates are fixed to the left and right ends of the lower end of the frame main body 30R of this seatback frame 24R by means of welding or other means. The thickness direction of these hinge mounting portions 34, 36 is primarily in the front-to-rear direction. Hinge portions 38, 40 made of press-formed metal plates are attached to these hinge mounting portions 34, 36. The thickness direction of these hinge portions 38, 40 is primarily in the left-to-right direction and protrudes forward from the lower end of the frame main body 30R.

[0026] The left hinge portion 38 is overlapped from the right side with a hinge bracket 42 attached to the floor of the vehicle body. The hinge bracket 42 is made of a pressed metal plate and is fixed to the floor of the vehicle body by means of bolts or the like. The left hinge portion 38 and the hinge bracket 42 are rotatably connected using a shoulder bolt and nut (not shown) whose axis is in the left-right direction.

[0027] The right hinge portion 40 is overlapped from the right side with a hinge bracket 44 attached to the side of the vehicle body. This hinge bracket 44 corresponds to the "first member" in the present invention and is composed, for example, of a bracket main body 46 and a torsion bar engagement portion 48. The bracket main body 46 is made of a pressed metal plate and is fixed to the side of the vehicle body by means of bolt fastening or the like. The right hinge portion 40 and the bracket main body 46 are rotatably connected using a shoulder bolt 50 whose axis is in the left-right direction and a nut (not shown). This allows the seat back frame 24R (i.e., the seat back 14R) to be rotatably connected to the vehicle body.

[0028] The torsion bar engaging portion 48 is made of a press-formed metal plate, and is located below the shoulder bolt 50 on the left side of the bracket main body 46. This torsion bar engaging portion 48 is made up of a joint portion 48A that is fixed to the bracket main body 46 by means of welding or the like, and an extension portion 48B that extends to the left from the joint portion 48A. The extension portion 48B has its plate thickness direction aligned with the radial direction of the shoulder bolt 50 and is curved along the circumferential direction of the shoulder bolt 50. An elongated hole 52 is formed in this extension portion 48B, with its longitudinal direction aligned with the circumferential direction of the shoulder bolt 50.

[0029] The right hinge mounting portion 36 has a torsion bar fixing portion 36A extending downward from the lower end of the hinge mounting portion 36. A base end 54A of a torsion bar 54 is fixed to the lower end of the torsion bar fixing portion 36A by welding or other means. As shown in FIGS. 3 and 4 , the torsion bar 54 is manufactured by bending a rod-shaped spring material with a circular cross section. The torsion bar 54 is fixed to the torsion bar fixing portion 36A and is composed of a base end 54A extending forward from the torsion bar fixing portion 36A, a torsional deformation portion 54B extending rightward from the front end of the base end 54A, and a tip end 54C extending downward from the right end of the torsional deformation portion 54B. The tip end 54C of the torsion bar 54 is inserted into the elongated hole 52 of the torsion bar engagement portion 48.

[0030] When the seat back 14R is rotated between the upright position indicated by the solid line in Fig. 5 and the forward-tilted position indicated by the two-dot chain line in Fig. 5 (i.e., when switching between the seatable state and the unseatable state), the seat back frame 24R rotates relative to the hinge bracket 44. When the seat back 14R is in the upright position, as shown in Fig. 6, the tip end 54C of the torsion bar 54 is pressed against the front end of the elongated hole 52, and the torsional deformation portion 54B of the torsion bar 54 is twisted in one direction about the axis. In this state, the seat back frame 24R, i.e., the seat back 14R, is biased toward the forward-tilted position by the torsion bar 54.

[0031] When the seat back 14R is positioned at the forward-folding assist end position L1 shown in Fig. 5, the tip 54C of the torsion bar 54 contacts the front end of the elongated hole 52, but the torsional deformation portion 54B of the torsion bar 54 is not twisted, as shown in Fig. 7. When the seat back 14R is positioned at the raising assist end position L2 shown in Fig. 5, the tip 54C of the torsion bar 54 contacts the rear end of the elongated hole 52, but the torsional deformation portion 54B of the torsion bar 54 is not twisted, as shown in Fig. 8. When the seat back 14R is positioned in the free section F between the forward-folding assist end position L1 and the raising assist end position L2 shown in Fig. 5, the tip 54C of the torsion bar 54 is located in the longitudinal middle portion of the elongated hole 52, and the torsional deformation portion 54B of the torsion bar 54 is not twisted.

[0032] 5, the tip 54C of the torsion bar 54 is pressed against the rear end of the elongated hole 52, and the torsional deformation portion 54B of the torsion bar 54 is twisted in the other direction around the axis, as shown in FIG. 9. In this state, the seat back frame 24R, i.e., the seat back 14R, is biased toward the forward-folded position by the torsion bar 54.

[0033] In the vehicle seat 10 configured as described above, when the seat back 14R is rotated from the forward-tilting position to the upright position (i.e., when switching from the non-seating state to the seatable state), the tip end 54C of the torsion bar 54 engages with one end (here, the front end) of the elongated hole 52, and the torsional deformation portion 54B of the torsion bar 54 is twisted in one direction about the axis. As a result, the seat back 14R located in the upright position is biased toward the forward-tilting position by the torsion bar 54, so that the operation of tilting the seat back 14R forward (i.e., switching the vehicle seat 10 from the seatable state to the non-seating state) can be assisted by the biasing force of the torsion bar 54.

[0034] Furthermore, when the seat back 14R is rotated from the upright position to the forward-tilting position (i.e., when switching from a seatable state to an unseatable state), the tip end 54C of the torsion bar 54 engages with the other end (here, the rear end) of the elongated hole 52, and the torsional deformation portion 54B of the torsion bar 54 is twisted in the other direction about the axis. As a result, the seat back 14R located in the forward-tilting position is biased toward the upright position by the torsion bar 54, so that the operation of raising the seat back 14R (i.e., switching the vehicle seat 10 from a seatable state to a seatable state) can be assisted by the biasing force of the torsion bar 54 (i.e., torsion bar spring). Moreover, since it is not necessary to place the torsion bar 54 (i.e., torsion bar spring) at the center of relative rotation between the seat back frame 24R and the hinge bracket 44, the flexibility of spring placement can be improved.

[0035] Next, various modifications of the above embodiment will be described. Note that the same reference numerals as those in the above embodiment and the modifications that have already been described are used to designate configurations and functions that are basically the same as those in the above embodiment and the modifications that have already been described, and descriptions thereof will be omitted.

[0036] In the modified example shown in FIG. 10 , a torsional deformation portion 54B of the torsion bar 54 is supported by a support portion 36B provided at the lower end of the hinge mounting portion 36. The support portion 36B is located to the right of the torsion bar fixing portion 36A and extends downward from the lower end of the hinge mounting portion 36, then bends and extends forward. A cut-and-raised portion 37 cut and raised upward is provided at the tip of the support portion 36B, and the torsional deformation portion 54B is sandwiched between the cut-and-raised portion 37 and another portion of the tip of the support portion 36B. This allows the torsional deformation portion 54B (i.e., the middle portion of the torsion bar 54) to be supported by the support portion 36B so as to be torsionally deformable. In this modified example, the torsional deformation of the torsion bar 54 can be stabilized.

[0037] 11, resin members 56, 58 are provided at one end and the other end of the elongated hole 52 of the torsion bar engagement portion 48 of the hinge bracket 44. The resin members 56, 58 are manufactured by, for example, resin injection molding, and are fixed to the extension portion 48B of the torsion bar engagement portion 48. When the seat back 14R is rotated between the upright position and the forward-leaning position, the tip end 54C of the torsion bar 54 comes into contact with each of the resin members 56, 58. This makes it easier to prevent point contact and ensure durability, compared to, for example, a configuration in which the tip end 54C of the torsion bar 54 directly comes into contact with one end and the other end of the elongated hole 52.

[0038] In the modified example shown in FIG. 12, a pull-out prevention member 60 is attached to the torsion bar engagement portion 48 of the hinge bracket 44. As shown in FIG. 13, the pull-out prevention member 60 is composed of, for example, a bolt-shaped member 62 formed in a generally bolt shape and a nut-shaped member 64 formed in a generally nut shape. The bolt-shaped member 62 and the nut-shaped member 64 are manufactured by, for example, resin injection molding. The bolt-shaped member 62 is inserted into the elongated hole 52, and the male thread formed on the bolt-shaped member 62 is screwed into the female thread of the nut-shaped member 64. This allows the pull-out prevention member 60 to be attached to the torsion bar engagement portion 48 slidably along the elongated hole 52. A hole 66 is formed in the center of the bolt-shaped member 62, into which the tip portion 54C of the torsion bar 54 is inserted.

[0039] 14 and 15, when the seat back 14R is rotated between the upright position and the forward-folded position, the retaining member 60 is configured to slide along the elongated hole 52 together with the tip portion 54C of the torsion bar 54. In this modified example, the retaining member 60 can prevent the tip portion 54C of the torsion bar 54 from accidentally coming out of the elongated hole 52.

[0040] 16, the base end 54A of the torsion bar 54 passes through the torsion bar fixing portion 36A of the hinge attachment portion 36. A through hole 68 that passes through in the up-down direction is formed in the base end 54A of the torsion bar 54 behind the torsion bar fixing portion 36A. A retaining pin 70 is inserted into this through hole 68. This modification can prevent the base end 54A of the torsion bar 54 from accidentally coming off the torsion bar fixing portion 36A.

[0041] 17, the torsional deformation portion 54B of the torsion bar 54 is arranged coaxially with the shoulder bolt 50 (i.e., coaxially with the central axis of relative rotation between the seat back frame 24R and the hinge bracket 44). This makes it possible to reduce loss of torque generated by torsional deformation of the torsional deformation portion 54B.

[0042] In the above embodiment and various modified examples, the elongated hole 52 is formed in the hinge bracket 44 and the torsion bar 54 is fixed to the seat back frame 24R, but this is not limiting, and the elongated hole 52 may be formed in the seat back frame 24R and the torsion bar 54 may be fixed to the hinge bracket 44.

[0043] Furthermore, in the above embodiment and various modified examples, the hinge bracket 44 is configured to be attached to the vehicle body, but this is not limited to this, and the hinge bracket 44 may also be configured to be attached to a seat cushion frame (not shown), which is the frame of the seat cushion 12.

[0044] In addition, in the above embodiment and various modified examples, the case where the forward tilting and raising of the seat back 14R is assisted by the torsion bar 54 has been described, but the present invention is not limited to this. For example, a configuration may be adopted in which the torsion bar assists the stowing operation and the unfolding operation of a vehicle seat that can be stored in the vehicle body floor.

[0045] In addition, the present invention can be implemented with various modifications within the scope of the gist thereof. Furthermore, it goes without saying that the scope of the present invention is not limited to the above-described embodiment and various modifications. [Explanation of symbols]

[0046] 10 Vehicle seats 24R Seat back frame (second component) 44 Hinge bracket (first member) 52 long hole 54 Torsion bar 54A Proximal end 54B Torsion deformation part (middle part) 54C Tip 56, 58 Resin parts 60 Stopper member

Claims

1. An operation assist structure for a vehicle seat that is provided on a vehicle seat that can be switched between a seating state in which an occupant can be seated and an unseating state in which an occupant cannot be seated, a first member having a slot formed therein; a second member that rotates relative to the first member by the switching operation; a torsion bar having a base end fixed to the second member, a tip end inserted into the elongated hole, and having the tip end engaged with one end of the elongated hole and twisted in one direction about the axis when switching from the non-seating state to the seating state, and the tip end engaged with the other end of the elongated hole and twisted in the other direction about the axis when switching from the seating state to the non-seating state; An operation assist structure for a vehicle seat.

2. one of the first member and the second member is a hinge bracket attached to a seat cushion frame of the vehicle seat or a vehicle body, The operation assist structure for a vehicle seat according to claim 1 , wherein the other of the first member and the second member is a seat back frame of the vehicle seat.

3. 3. The vehicle seat operation assist structure according to claim 1, wherein the second member has a support portion that supports an intermediate portion of the torsion bar between the base end portion and the tip end portion so as to be torsionally deformable.

4. 3. The operation assist structure for a vehicle seat according to claim 1, wherein a resin member made of resin is provided at the one end and the other end of the long hole, against which the tip of the torsion bar comes into contact during the switching operation.

5. 3. The operation assist structure for a vehicle seat according to claim 1, further comprising a hole into which the tip of the torsion bar is inserted, and a retaining member attached to the first member so as to be slidable along the long hole.

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