Locking mechanism and chair

Abstract

To provide a lock mechanism capable of simplifying a structure and undamaging freedom of design, and a chair.SOLUTION: A lock mechanism includes: a first member; a second member movable relative to the first member; an energizing member energizing the first member toward one side in a second direction; a regulation member displaceable between a locked state and an unlocked state; and an operation part operating the regulation member. The regulation member includes: a support part supported by the first member rotatably around an axial line; an engaging part leaving a second engaging hole in the unlocked state while engaging the second engaging hole formed in the second member through a first engaging hole formed in the first member in the locked state; and an energy storing part capable of storing an energizing force in the direction in which the engaging part leaves the second engaging hole by being compressed and transforming.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a locking mechanism and a chair. [Background technology]

[0002] Conventionally, chairs used for office work, etc., equipped with a mechanism for temporarily releasing the rotation restriction state of the backrest relative to the support structure (hereinafter, sometimes referred to as a locking mechanism) are known. In such chairs, a biasing force is generated by operating a pull-lock / pull-release function to keep the locking member from disengaging from the sector gear, and in this state, a load is applied to the backrest to switch the backrest to a rotatable state (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4638116 Summary of the Invention [Problem to be solved by the invention]

[0004] The locking mechanism disclosed in Patent Document 1 requires guide members for guiding the two types of built-in springs, making the structure extremely complicated. In addition, it also requires the formation of a surface to slidably support the locking member, which places many constraints on the design.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a locking mechanism and a chair that can simplify the configuration and do not impair the degree of freedom in design. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the locking mechanism of the present invention comprises a first member, a second member arranged overlapping the first member when viewed from a first direction and movable relative to the first member in a second direction intersecting the first direction, a biasing member interposed between the first member and the second member and biasing the first member toward one side of the second direction, a restricting member movable between a locked state that restricts relative movement between the first member and the second member in the second direction and an unlocked state that allows relative movement between the first member and the second member in the second direction, and an operating unit that operates the restricting member, and comprises an engaging portion that engages with a second engaging hole formed in the second member through a first engaging hole formed in the first member in the locked state and disengages from the second engaging hole in the unlocked state, and a biasing force storage portion connected to the engaging portion and elastically deforms by operation of the operating unit to store a biasing force in a direction in which the engaging portion disengages from the second engaging hole.

[0007] In this aspect of the invention, the first member is biased toward one side in the second direction by the biasing member, so that in the locked state, the engaging portion is sandwiched in the second direction by the inner surfaces of the first engaging hole and the second engaging hole. As a result, the engaging portion is restricted from moving in a direction away from the second engaging hole by a frictional force resulting from a shear load in the second direction acting from the inner surfaces of the first engaging hole and the second engaging hole. As a result, in the locked state, the energy storage portion can be elastically deformed to store in the energy storage portion a biasing force that disengages the engaging portion from the second engaging hole. In this state, by moving the first member and the second member against the biasing force of the biasing member, the engaging portion can be disengaged from the second engaging hole by the biasing force stored in the energy storage portion. In this way, a biasing force can be stored in the energy storage portion by the shear load acting on the engagement portion from the first engagement hole and the second engagement hole, and the stored biasing force disengages the engagement portion from the second engagement hole. This reduces design restrictions on the shapes of the first member, the second member, and other members located around them. This simplifies the configuration of the locking mechanism and prevents loss of design freedom.

[0008] In the locking mechanism of the present invention, the energy storage portion includes a support portion supported by the first member so as to be rotatable about an axis along a third direction that intersects the second direction when viewed from the first direction, and the engagement portion may engage with or disengage from the second engagement hole as the regulating member rotates around the support portion.

[0009] This configuration allows the energy storage portion to be deformed stably, and also allows the amount of displacement of the engaging portion to be adjusted appropriately depending on the position of the support portion in the energy storage portion.

[0010] In the locking mechanism according to the present invention, the energy storage portion may be formed in the shape of a leaf spring.

[0011] This configuration allows the energy accumulator to have a simple shape and to be placed in a relatively small space without affecting the shapes of the first member, the second member, and other members located around them.

[0012] In the locking mechanism according to the present invention, the energy storage portion may be formed in an arc shape that protrudes in a direction in which the engaging portion engages with the second engaging hole.

[0013] With this configuration, the energy storage portion can be compressively deformed in a direction that reduces the radius of curvature, thereby storing a biasing force in the energy storage portion. The biasing force stored by the compressive deformation functions as a biasing force in a direction that disengages the locking portion from the second engagement hole. This allows the engagement portion to smoothly disengage from the second engagement hole when the shear load acting on the engagement portion from the first engagement hole and the second engagement hole is released.

[0014] In the locking mechanism of the present invention, the operating unit may be movable between a disengagement position in which the engaging unit deforms the storage unit in a direction in which it disengages from the second engaging hole and an engagement position in which the engaging unit deforms the storage unit in a direction in which it engages with the second engaging hole, and may include a holding unit that holds the operating unit in each of the disengagement position and the engagement position.

[0015] With this configuration, the operating portion can be easily and reliably maintained in the disengaged position or the engaged position, thereby improving the operability of the locking mechanism.

[0016] In the locking mechanism according to the present invention, a plurality of second engagement holes may be arranged in the second direction.

[0017] With this configuration, the relative position between the first member and the second member in the second direction can be adjusted in stages.

[0018] The chair according to the present invention includes the locking mechanism, a backrest including the first member, and a support base including the second member and rotatably supporting the backrest.

[0019] The present invention can provide a chair that can be restricted to a predetermined tilting state while simplifying the configuration and not impairing the degree of freedom in design.

[0020] In the chair of the present invention, the backrest comprises a backrest main body that supports the back of the seated person and a backrest support member that supports the backrest main body, and the backrest support member has a rear wall on which a base portion that supports the rear end of the urging member is provided, and a storage space in which the regulating member is arranged may be formed between the rear wall and the base portion.

[0021] With this configuration, for example, it is possible to suppress interference between the restricting member and the biasing member, and also to ensure a space for arranging the restricting member. [Effects of the Invention]

[0022] According to the present invention, the configuration can be simplified without impairing the degree of freedom in design. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective view of a chair according to an embodiment of the present invention. [Figure 2]This is a perspective view of the chair with the upholstery removed, seen from diagonally behind. [Figure 3] FIG. [Figure 4] FIG. 1 is a side view with the rear cover removed. [Figure 5] FIG. [Figure 6] FIG. 6 is a plan view of FIG. 5. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. [Figure 8] FIG. 8 is a cross-sectional view of the spring rear end support portion of FIG. 7, arranged upward. [Figure 9] FIG. 2 is a perspective view showing a base member and a support member. [Figure 10] 10 is a cross-sectional view illustrating a state in which the convex portion of the connection member is fitted into the second concave portion. FIG. [Figure 11] FIG. 11 is an enlarged cross-sectional view of a portion XI in FIG. [Figure 12] 10 is a cross-sectional view showing a state in which the engaging portion is not in contact with the engaging recessed portion. FIG. [Figure 13] 10 is a cross-sectional view showing a state in which the engaging portion is disengaged from the engaging recessed portion. FIG. [Figure 14] 10 is a cross-sectional view showing a state in which an engagement portion is displaced from an engagement recess. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, a chair according to an embodiment of the present invention will be described with reference to FIGS. In the following explanation, for the sake of convenience, the direction in which an occupant seated in a normal posture on seat 17 faces forward will be referred to as "forward," and the opposite direction will be referred to as "rearward." Furthermore, the terms "up, down," and "left, and right" in the following explanation refer to directions that correspond to the direction centered on the occupant when seated in a normal posture on seat 17. Note that an arrow FR pointing forward, an arrow UP pointing upward, and an arrow LH pointing to the left are shown in appropriate locations in the drawings.

[0025] As shown in Figure 1, the chair 1 of this embodiment comprises legs 10 placed on the floor surface F, a box-shaped support base 40 placed on top of the legs 10, a seat 17 attached to the top of the support base 40, a backrest 20 attached to the rear of the support base 40 to support the back of the seated person, and armrests 19 extending above the seat 17 from both sides of the lower side of the seat 17 and on which the seated person's elbows and arms can be rested.

[0026] The leg 10 has a multi-leg 11 with casters 11a, and a pillar 12 that stands up from the center of the multi-leg 11 and has a built-in gas spring (not shown) that serves as a lifting mechanism. The pillar 12 has an outer cylinder 13 and an inner cylinder 14. The outer cylinder 13 is fitted and supported on the multi-leg 11 so as not to rotate. The lower part of the inner cylinder 14 is supported by the outer cylinder 13 so as to be rotatable in the horizontal direction. The upper part of the inner cylinder 14 is fixed to a support base 40.

[0027] The backrest 20 has a backrest structure 20A (see FIG. 2) and an upholstery material 26 that covers the backrest structure 20A. The backrest structure 20A supports the back of a seated occupant. As shown in FIG. 2, the backrest structure 20A has a backrest support 21 and a backrest main body 23 supported by the backrest support 21. The backrest support 21 supports the back of the seated occupant. The backrest support 21 has a backrest support member 30 and a rear overhang member 22.

[0028] 3 and 4, the backrest support member 30 is provided with a rotating member 38 that is rotatable via a rotation main shaft 42 that extends in the left-right direction at the rear of a support base 40. The rotating member 38 is rotatable about an axis in the left-right direction relative to the support base 40. The rotating member 38 is covered from the rear with a rear cover 37 (see also FIG. 2).

[0029] 1 and 2, the backrest 20 configured in this manner is supported by the backrest support member 30 so as to be rotatable about an axis along the left-right direction of the backrest support member 30, and is provided so as to be displaceable from an initial state in which the upper end 20a is positioned relatively forward to a tilted state in which the upper end 20a is positioned relatively rearward. In the initial state, the front surface of the backrest 20 faces forward. In the tilted state, the front surface of the backrest 20 is tilted rearward relative to the initial state.

[0030] A seat shell 51 that holds the seat 17 from below is provided below the seat 17. The seat shell 51 is provided on a seat support member 50 that is supported from below by the support base 40. The seat shell 51 is secured to the front edge 50a of the seat support member 50 with securing means such as screws, with a securing portion (not shown) provided on the underside of the rear end of the seat shell 51 being hooked onto the seat support member 50 from behind.

[0031] 3 and 4, the seat support member 50 has a spring front end support portion 55 fixed to the front portion of the main body portion 52. The spring front end support portion 55 will be described later with reference to FIGS. 5 and 6. The seat support member 50 is a strong member made of a metal material such as drawn sheet metal or aluminum die-cast, and has a saucer shape that is open on the top in the vertical direction. The seat receiving member 50 has a bottom wall portion 501. The bottom wall portion 501 is formed so as not to interfere with a compression coil spring 61, which will be described later.

[0032] The seat support member 50 has a rear attachment portion 53 provided on the rotating member 38, which will be described later, and is rotatably connected to a countershaft 39 of an operating means 80, which will be described later. The seat support member 50 is rotatable around the countershaft 39 relative to the rotating member 38. In other words, when the backrest 20 is tilted from the initial state in the direction of arrow A, the seat support member 50 moves rearward relative to the support base 40 in the direction of arrow B.

[0033] 5 to 7, the spring front end receiving portion 55 has fixed portions 551 provided on both left and right sides and fixed to the underside of the bottom wall portion 501, and a front spring reaction force receiving shaft 553 (see FIG. 7) that is inserted through and supported by the fixed portions 551 and extends axially in the left and right direction. An insertion hole 551a (see FIG. 5) through which the front spring reaction force receiving shaft 553 is inserted is formed in the fixed portion 551.

[0034] The front spring reaction force receiving shaft 553 is a rod material with a circular cross section. Both axial ends of the front spring reaction force receiving shaft 553 are inserted into the insertion holes 551a of the fixed part 551 and fixed so as not to move in the left-right direction relative to the fixed part 551. The front spring reaction force receiving shaft 553 supports the front ends of two compression coil springs 61 that are biased in the compression direction from the rear.

[0035] The support base 40 comprises a support base body portion 41 fixed to the upper part of the leg pillar 12, a pivot main shaft 42 that rotatably supports the pivot member 38 of the backrest support member 30 relative to the support base body portion 41, a slide engagement portion 43 that supports the seat support member 50 so that it can slide in the front-to-rear direction, and a plurality of engagement recesses (second engagement holes) 44.

[0036] The rear part of the support base body 41 is disposed so as to overlap the rotating member 38 when viewed from a first direction X described below, and is slidable relative to the rotating member 38 in a second direction Y described below that intersects with the first direction X. The support base body 41 has a bottom plate 411 and side plates 412 extending upward from both the left and right sides of the bottom plate 411, and is formed into a bowl shape that opens upward as a whole. Two compression coil springs (biasing members) 61 are housed in a first internal space S1 defined by the support base body 41.

[0037] The front part of the rotating member 38 of the backrest support member 30 is rotatably supported by a rotating shaft 42 on the inside rear part of the support base body 41. The rotating shaft 42 is provided on each of the left and right side plates 412. The rotation centers of the left and right rotating shafts 42 are coaxial.

[0038] The slide engagement portions 43 are provided on the front upper ends 412b of the side plates 412 on both the left and right sides of the support base body 41 in a state where they protrude upward. The slide engagement portions 43 have a protrusion 431 and a sliding portion 432 that is provided on the upper end of the protrusion 431 and has a larger diameter than the protrusion 431. The protrusion 431 is formed in a circular cross section with a diameter dimension that is approximately the same as the width dimension of the elongated hole (not shown) of the seat receiving member 50. With the protrusion 431 inserted into the elongated hole of the seat receiving member 50, the sliding portion 432 of the slide engagement portion 43 is disposed inside the seat receiving member 50. When the backrest 20 tilts, the slide engagement portion 43 can slide the elongated hole of the seat support member 50 rearward. That is, when the backrest 20 tilts (see arrow A in FIG. 4), the slide engagement portion 43 and the elongated hole of the seat support member 50 can move the seat support member 50 rearward (see arrow B in FIG. 4).

[0039] A locking mechanism 90 is provided between the support base body 41 of the support base 40 and the rotating member 38, and is capable of restricting the backrest 20 between its initial state and a tilted state. The locking mechanism 90 includes a return means 92, a restriction means 93, a rotating member (first member) 38 on the backrest 20 side, and a support base body (second member) 41 on the support base 40 side. The return means 92 returns the backrest 20 (see FIG. 2) from a tilted state to its initial state. The restriction means 93 restricts the rotation of the backrest 20 around the rotation main shaft 42.

[0040] The return means 92 includes a biasing means 60 having a compression coil spring 61 that biases the backrest 20 in a tilted state in a direction returning it to its initial state, an adjustment means 70 that adjusts the biasing force of the compression coil spring 61, and an operating means 80 that is connected to the adjustment means 70 and operates the adjustment means 70.

[0041] The rotating member 38 has a rear wall 381 and a pair of side walls 382 extending forward from both left and right ends of the rear wall 381. The adjustment means 70 and a part of the operating means 80 are housed in a second internal space S2 defined by the rotating member 38. In addition, the rear end of the compression coil spring 61 is disposed in the front part of the second internal space S2.

[0042] The pair of side walls 382 are rotatably supported by the rotation main shaft 42 relative to the rear upper portion 412a of the side plate 412 of the support base portion 41. The rotation member 38 supports the rotation main shaft 42 at its front portion. The rotation member 38 also has a sub-shaft 39 at its rear portion to which the rear mounting portion 53 (see FIG. 4) of the seat receiving member 50 is attached. The rotation member 38 supports an operating shaft 81 of the operating means 80 at a portion intermediate between its front and rear portions.

[0043] The counter shaft 39 extends in the left-right direction and is supported between the pair of side walls 382. A connecting piece 532 formed on the rear mounting portion 53 of the seat support member 50 is rotatably supported on the counter shaft 39. In other words, the rear portion of the seat support member 50 is rotatably supported with respect to the rotating member 38.

[0044] The biasing means 60 has a return force (reaction force) for returning the backrest 20 tilted by the biasing force to its original position (initial state). The biasing means 60 has a compression coil spring 61, a spring front end support portion 62 provided at one end (front end) of the compression coil spring 61, and a spring rear end support portion 63 provided at the other end (rear end).

[0045] The compression coil springs 61 are compressed from both sides in the front-to-rear direction. Two compression coil springs 61, with their biasing direction facing the front-to-rear direction, are housed side by side in the left-to-right direction in the first internal space S1 of the support basic body 41. The pair of compression coil springs 61 are attached in a constantly compressed and biased state, whether the backrest 20 is in the initial state or the tilted state. The compression coil spring 61 is interposed between the rotating member 38 and the support basic body 41, and biases the rotating member 38 toward one side in the second direction Y (upward in this embodiment).

[0046] The spring front end support portion 62 and the spring rear end support portion 63 are connected by an expandable connecting shaft 64 that is inserted inside the compression coil spring 61. In the biasing means 60, the expandable connecting shaft 64 expands and contracts as the distance between the spring front end support portion 62 and the spring rear end support portion 63 changes due to the compression and extension of the compression coil spring 61.

[0047] The spring front end support portion 62 abuts against the front end of the compression coil spring 61 from the front. The spring front end support portion 62 is formed in a U-shape that opens forward when viewed from the left and right. The recess 62a is engaged with the front spring reaction force receiving shaft 553 of the spring front end receiving portion 55 provided on the seat receiving member 50, while being pressed from behind. In other words, the front spring reaction force receiving shaft 553 bears the reaction force of the compression coil spring 61 whether the backrest 20 is in the initial state or the tilted state.

[0048] The spring rear end support portion 63 abuts against the rear end of the compression coil spring 61 from behind. The spring rear end support portion 63 has a through hole 631 (see FIG. 7) that penetrates in the left-right direction. The action shaft 71 (shaft portion 712) of the adjustment means 70 is inserted through the through hole 631. The spring rear end support portion 63 is in a state in which the biasing force of the compression coil spring 61 is applied from the front to the action shaft 71. In other words, the action shaft 71 bears the reaction force of the compression coil spring 61 whether the backrest 20 is in the initial state or the tilted state.

[0049] 7 and 8, the adjustment means 70 has a function of adjusting the biasing force of the compression coil spring 61 and adjusting the restoring force of the tilted backrest 20. The adjustment means 70 is housed between the side walls 382 (second internal space S2) of the rotating member 38. The adjustment means 70 constitutes a so-called ball screw mechanism and includes an action shaft 71 that acts on the biasing force of the biasing means 60 (compression coil spring 61), an adjustment shaft 72 that movably supports the action shaft 71, and a support member (base portion) 73 that rotatably supports the adjustment shaft 72 with respect to the operation means 80.

[0050] A male thread is formed on the outer peripheral surface of the adjustment shaft 72. A second transmission gear 721 made of a bevel gear is integrally provided at the upper end of the adjustment shaft 72. This second transmission gear 721 meshes with a first transmission gear 83 of the operating means 80, and by operating the operating means 80, a rotational force is transmitted from the first transmission gear 83 to the second transmission gear 721, causing the adjustment shaft 72 to rotate in both forward and reverse directions. A male thread is formed on the adjustment shaft 72 over the entire axial direction, with which the working shaft 71 is threadedly engaged.

[0051] The adjustment shaft 72 is disposed such that the axial direction gradually points obliquely upward and rearward as it moves from the lower shaft end 72b to the upper shaft end 72a in a side view. The lower shaft end 72b is located below the main turning shaft 42. The upper shaft end 72a is located above and rearward of the main turning shaft 42. In other words, the operating shaft 71 (spring rear end support portion 63) is configured to move between a position below the main turning shaft 42 (position shown in FIG. 7) and a position above and rearward of the main turning shaft 42 (position shown in FIG. 8).

[0052] The adjustment means 70 is configured so that, as the adjustment shaft 72 rotates, the action shaft 71, which is threaded onto the male screw, moves in the axial direction of the adjustment shaft 72 according to the rotational position of the adjustment shaft 72. That is, the adjustment means 70 can adjust the position of the action shaft 71 by moving the action shaft 71 along the adjustment shaft 72. When the action shaft 71 moves on the adjustment shaft 72, the compression coil spring 61 rotates about the spring front end support portion 62, and therefore only the angle as viewed from the left and right changes.

[0053] As shown in FIGS. 6, 7, and 9, the support member 73 includes a fixed plate 731 that extends in the vertical direction and is fixed to the rear wall 381 of the rotating member 38 with screws (not shown), an upper support plate 732 and a lower support plate 733 that extend forward from the upper and lower ends of the fixed plate 731, and a pair of side support plates 734, 735 that extend upward from both left and right sides of the upper support plate 732. Of the pair of side support plates 734, 735, the left side support plate 734 will be referred to as the first side support plate 734, and the right side support plate 735 will be referred to as the second side support plate 735. The adjustment shaft 72 is disposed between the upper support plate 732 and the lower support plate 733. The adjustment shaft 72 has an upper shaft end 72a rotatably supported by the upper support plate 732 and a lower shaft end 72b rotatably supported by the lower support plate 733.

[0054] The action shaft 71 includes a nut portion 711 having a female thread that screws onto the adjustment shaft 72, and a shaft portion 712 that extends to both the left and right sides of the nut portion 711. The nut portion 711 moves along the adjustment shaft 72 as the adjustment shaft 72 rotates. The spring rear end support portion 63 of the biasing means 60 is connected to the shaft portion 712.

[0055] 5 and 6, the operating means 80 is provided on the rotating member 38. The operating means 80 has an operating shaft 81 extending in the left-right direction, an operating lever 82 provided at the tip of the operating shaft 81 that protrudes outward from a side wall 382, ​​and a first transmission gear 83 made of a bevel gear provided at the middle part of the operating shaft 81 and located in the second internal space S2. That is, the operating means 80 has the outer left-right end of the operating shaft 81 protruding left-right from the side wall 382, ​​while the inner left-right end is positioned within the second internal space S2 and connected to the adjustment means 70.

[0056] The operating shaft 81 is rotatably supported on the upper portions of the side walls 382 on both the left and right sides of the rotating member 38. The operating shaft 81 is disposed above the adjustment shaft 72 so that the axis of the operating shaft 81 and the axis of the adjustment shaft 72 are positioned in the same plane. The operating shaft 81 is supported on a base member 91 (see FIG. 9 ) that is supported on the support member 73. As shown in FIG. 6 , the movement of the operating shaft 81 in the left-right direction relative to the side wall 382 is restricted by a flange portion 81a integrally formed with a portion positioned on the outer side (right side) of the side wall 382, ​​and a stopper ring 84 provided on the inner side (left side) of the side wall 382. The stopper ring 84 is, for example, a C-ring, and is fitted onto the operating shaft 81.

[0057] The first transmission gear 83 meshes with a second transmission gear 721 provided on the adjustment shaft 72. In other words, the rotation of the operation shaft 81, i.e., the rotation of the first transmission gear 83 around its axis in the left-right direction, is converted into the rotation of the second transmission gear 721 around the axis of the adjustment shaft 72.

[0058] In chair 1 (see FIG. 1) configured in this manner, when adjusting the reaction force (returning force) of backrest 20 (see FIG. 1), first, operating lever 82 of operating means 80 is rotated, causing action shaft 71 located at spring rear end support portion 63 of compression coil spring 61 to move up and down along adjustment shaft 72. For example, by rotating operating lever 82 in one direction, adjustment shaft 72 rotates in one direction via first transmission gear 83 and second transmission gear 721, and nut portion 711 screwed onto adjustment shaft 72, i.e., action shaft 71, moves up along adjustment shaft 72.

[0059] In this way, by moving the action shaft 71 on the adjustment shaft 72, the distance between the spring front end support portion 62 and the spring rear end support portion 63 of the biasing means 60 changes, and the compression amount of the compression coil spring 61, i.e., the biasing force (reaction force) of the compression coil spring 61, can be adjusted. That is, it is possible to adjust the restoring force when the backrest 20 returns from the tilted state to the initial state.

[0060] In the adjustment means 70 of this embodiment, the position of the action shaft 71, i.e., the position of the spring rear end support portion 63 of the compression coil spring 61, is changed by moving the action shaft 71 on the adjustment shaft 72, thereby adjusting the biasing force of the compression coil spring 61 (the return force of the backrest). In this embodiment, as shown in Fig. 8, the action shaft 71, which moves on the adjustment shaft 72, can be adjusted to a position above the rotation main shaft 42 in the vertical direction.

[0061] 5 and 9, the first-side support plate 734 and the second-side support plate 735 are flat plates with their surfaces facing the left-right direction. The first-side support plate 734 and the second-side support plate 735 are disposed facing each other in the left-right direction. The first-side support plate 734 and the second-side support plate 735 are formed with holes 734a (the holes in the second-side support plate 735 are not shown) that penetrate in the left-right direction at positions facing each other in the left-right direction. The holes 734a formed in the first-side support plate 734 are referred to as first holes 734a, and the holes formed in the second-side support plate 735 are referred to as second holes. The base member 91 is inserted through the first hole 734a and the second hole 734b. The base member 91 supports the operating shaft 81 of the return means 92 and the operating shaft 951 of the restriction means 93.

[0062] The base member 91 is a rod-shaped member with an axis extending in the left-right direction. The left end of the base member 91 protrudes leftward beyond the side support plate 734. The right end of the base member 91 protrudes rightward beyond the side support plate 735. The middle portion of the base member 91 in the lengthwise direction (left-right direction) is referred to as middle portion 911, the left side of middle portion 911 is referred to as first support portion 912, and the right side of middle portion 911 is referred to as second support portion 913. The cross-sectional shape of the intermediate portion 911 and the first support portion 912 is circular. The cross-sectional shape of the second support portion 913 is a polygon (for example, a rectangle) that is larger than the cross-sectional shape of the intermediate portion 911.

[0063] A left end 911a of an intermediate portion 911 of the base member 91 is inserted into the first hole portion 734a. The first hole portion 734a is a round hole. The inner diameter of the first hole portion 734a is the same as or slightly larger than the outer diameter of the intermediate portion 911. The intermediate portion 911 is rotatable around the axis of the base member 91 relative to the first side support plate 734. The first support portion 912 is disposed on the left side of the first side support plate 734.

[0064] The left end of the second support part 913 is inserted into the second hole part. The boundary between the second support part 913 and the intermediate part 911 is located to the left of the second-side support plate 735, i.e., on the first-side support plate 734 side. The second hole part is a round hole. The inner diameter of the second hole part is larger than the outer diameter of the second support part 913. The second support part 913 is rotatable around the axis of the base member 91 relative to the second-side support plate 735.

[0065] The base member 91 is rotatable about the axis of the base member 91 relative to the support member 73 in a state where it is inserted into the first hole portion 734a and the second hole portion. A first recess 736 and a second recess 737 are formed side by side in the circumferential direction (the direction around the axis of the base member 91) at the upper edge of the first-side support plate 734. The first recess 736 is disposed forward of the second recess 737. A protrusion 738 is formed between the first recess 736 and the second recess 737. The first recess 736 and the second recess 737 are configured to fit into a protrusion 943a (see FIG. 10) of the connecting member 94, which will be described later.

[0066] The second support part 913 is inserted into the left end part of the operating shaft 81. In this state, the operating shaft 81 and the second support part 913 (i.e., the base member 91) are fixed so as not to rotate relative to each other around the axis of the base member 91. The first transmission gear 83 has a gear main body 831 on which a gear is formed, and a gear fixing portion 832 that is provided coaxially with the gear main body 831 and fixed to the base member 91. The axis of the first transmission gear 83 extends in the left-right direction, and the gear main body 831 is disposed to the left of the gear fixing portion 832. The first transmission gear 83 has a hole 833 formed therethrough in the axial direction. The base member 91 (second support portion 913) is fitted into the hole 833 of the first transmission gear 83, and the first transmission gear 83 and the base member 91 are fixed so as not to rotate relatively around the axis of the base member 91. In other words, when the operating shaft 81 rotates around the axis of the base member 91, the first transmission gear 83 also rotates integrally. Note that the base member 91 is rotatable around the axis of the base member 91 relative to the support member 73, and therefore the support member 73 does not rotate even when the base member 91 rotates.

[0067] 5, 7, and 10, the restricting means 93 restricts the rotation of the backrest 20 around the rotation main shaft 42. The restricting means 93 includes an engaging member (restricting member) 96 having an engaging portion 961 that is inserted into one of the plurality of engaging recesses 44 provided in the support base 40, an operating member (operating portion) 95 that operates the engaging member 96, and a connecting member (operating portion) 94 that connects the engaging member 96 and the operating member 95. The engaging member 96, the operating member 95, and the connecting member 94 are supported by the base member 91. A plurality of the engaging recesses 44 are lined up at intervals in the second direction Y on the rear part of the bottom plate 411.

[0068] The operating member 95 has an operating shaft 951 extending in the left-right direction, and an operating lever 952 (see FIG. 1) connected to the left end of the operating shaft 951. The operating shaft 951 is supported by the base member 91 so as to be rotatable about the axis of the base member 91. As shown in FIG. 6, the movement of the operating shaft 951 in the left-right direction relative to the side wall 382 is restricted by a flange portion 951a integrally formed with a portion located on the outer side (left side) of the side wall 382, ​​and a stopper ring 953 provided on the inner side (right side) of the side wall 382.

[0069] The connecting member 94 connects the operating member 95 and the base member 91 while straddling the first-side support plate 734 from above. The connecting member 94 is rotatably supported by the base member 91 (middle portion 911) on the right side of the first-side support plate 734. The connecting member 94 is fixed to the operating shaft 951 on the left side of the first-side support plate 734. That is, the connecting member 94 rotates relative to the base member 91 about the axis of the base member 91 as the operating lever 952 is rotated, and can rotate integrally with the operating shaft 951. A convex portion 943a that protrudes downward is formed on a portion of the connecting member 94 located above the first-side support plate 734. The connecting member 94 is positioned in the left-right direction relative to the operating shaft 95, the operating shaft 81, and the support member 73 by a displacement restriction means (not shown).

[0070] The protrusion 943a is disposed in either the first recess 736 or the second recess 737 of the first-side support plate 734 as a result of the connecting member 94 rotating about the axis of the base member 91. In FIG. 7, the protrusion 943a is disposed in the first recess 736. In FIG. 10, the protrusion 943a is disposed in the second recess 737. The protrusion 943a elastically deforms when it rides over the protrusion 738 between the first recess 736 and the second recess 737.

[0071] When the operating member 95 is operated to rotate around the axis of the base member 91, the connecting member 94 also rotates integrally with the operating member 95. The rotation of the operating member 95 stops at either an engagement position where the convex portion 943a of the connecting member 94 fits into the first concave portion 736 or a disengagement position where the convex portion 943a fits into the second concave portion 737. When the operating member 95 is stopped at the engagement position, the restricting means 93 elastically deforms a second linkage portion 964 (described later) in a direction in which the engaging portion 961 engages with (inserts) the engaging recess 44. Furthermore, when the operating member 95 is stopped at the disengagement position, the restricting means 93 deforms the second linkage portion 964 in a direction in which the engaging portion 961 comes out of the engaging recess 44.

[0072] In the following description, the sliding movement direction (movement direction) in which the engaging portion 961 is inserted into and removed from the engaging recess 44 is referred to as the "first direction X," and the direction intersecting the first direction X is referred to as the "second direction Y." Furthermore, the direction intersecting the second direction Y as viewed from the first direction X is referred to as the "third direction." In this embodiment, the first direction X indicates the tangent direction of an imaginary circle that is centered on the main pivot shaft 42 and passes through the rear surface of the rear wall 381. When the backrest 20 tilts around the main pivot shaft 42 as a starting point, the rotating member 38 moves linearly approximately along the first direction X within the range in which the engaging portion 961 passes between the multiple engaging recesses 44. Therefore, in the following description, the movement direction of the rotating member 38 relative to the support base body 41 when the backrest 20 tilts is referred to as the first direction X. In this embodiment, the third direction coincides with the left-right direction.

[0073] A leaf spring is used as the engaging member 96, for example. When the operating member 95 is in the engaged position, the engaging member 96 biases the engaging portion 961 in a direction to be inserted into the engaging recess 44 (the state in FIG. 14). When the operating member 95 is in the disengaged position, the engaging member 96 biases the engaging portion 961 in a direction to be ejected from the engaging recess 44 (the state in FIG. 10).

[0074] The engaging member 96 extends upward from a portion of the connecting member 94 located to the right of the first-side support plate 734, then curves rearward and extends downward through the rear of the compression coil spring 61 (between the support member 73 and the rear wall 381). Specifically, an accommodation groove (accommodation space) 381a recessed rearward is formed in a position of the rear wall 381 facing the fixing plate 31. The accommodation groove 381a opens at least on the upper edge of the rear wall 381 and extends in the vertical direction along the rear wall 381. The engaging member 96 enters the accommodation groove 381a through the upper opening of the accommodation groove 381a and extends downward within the accommodation groove 381a. In the illustrated example, the engaging member 96 is arranged in the accommodation groove 381a in a state in which it is tilted forward as it extends downward.

[0075] The engagement member 96 includes a shaft portion (support portion) 962 having an axis extending in the left-right direction (third direction) at its vertically intermediate portion, a first linkage portion 96a extending downward from the shaft portion 962, an engagement portion 961 provided at the lower end of the first linkage portion 96a, and a second linkage portion 964 extending upward from the shaft portion 962. The engagement member 96 is configured to be rotatable about the axis extending in the left-right direction, starting from the shaft portion 962. The shaft portion 962, the first linkage portion 96a, and the second linkage portion 964 form the energy storage portion of this embodiment.

[0076] The shaft portion 962 is located below the axis of the base member 91 and above the engagement recess 44. The shaft portion 962 is supported between the rotating member 38 and the support member 73. Specifically, the rear surface of the shaft portion 962 is formed in an arc shape that convex toward the rear in a side view. The rear surface of the shaft portion 962 is disposed within a sliding recess 381b formed on the inner surface of the accommodation groove 381a. That is, as the engaging member 96 rotates, the rear surface of the shaft portion 962 slides on the inner surface of the sliding recess 381b. In the engaging member 96, the shaft portion 962 has a support protrusion 962a that faces forward (diagonally upward and forward). The front surface of the support protrusion 962a is formed in an arc shape with a larger radius of curvature than the rear surface of the shaft portion 962. The front surface of the support protrusion 962a slides on the rear surface of the fixing plate 731 as the engaging member 96 rotates. In this way, the engaging member 96 is supported on the backrest 20 (see FIG. 2) so as to be rotatable about the shaft 962, with the shaft 962 sandwiched between the fixed plate 731 and the rear wall 381. The support structure of the engaging member 96 can be changed as appropriate. The engaging member 96 may be supported on the backrest 20 by a pin or the like, for example.

[0077] The first linking portion 96a extends downward within the accommodation groove 381a, following the contour of the rear wall 381. The first linking portion 96a is configured to be elastically deformable in the first direction X. An allowance hole 96b is formed at the lower end of the first linking portion 96a, penetrating the first linking portion 96a in the left-right direction. The allowance hole 96b is an elongated hole with the second direction Y as its longitudinal direction.

[0078] The engagement portion 961 is provided at the lower end of the first linkage portion 96a. The engagement portion 961 protrudes from the first linkage portion 96a in the first direction X. The engagement portion 961 is attached to the first linkage portion 96a by inserting a support pin 961a through an allowable hole 96b. That is, the engagement portion 961 is configured to be movable relative to the first linkage portion 96a within the range of the allowable hole 96b in the second direction Y. The engagement portion 961 is configured to be insertable into and removable from (engageable with) the engagement recess 44 through a hole portion (first engagement hole) 383 provided in the rear wall 381. As shown in FIG. 11 , guide grooves 384 are formed in portions of the rotating member 38 located on both sides of the engagement portion 961 in the left-right direction. The guide grooves 384 are recessed outward in the left-right direction and extend along the first direction X. The guide groove 384 guides the movement of the engaging portion 961 in the first direction X while accommodating both left and right end portions of the engaging portion 961.

[0079] The second linkage portion 964 is formed in an arc shape that convexes rearward in a side view. In other words, the second linkage portion 964 is formed in an arc shape (curved shape) that convexes in the direction in which the engagement portion 961 engages with the engagement recess 44 in the first direction X. The upper end of the second linkage portion 964 is connected to the connecting member 94 via a link portion 963. The second linkage portion 964 elastically deforms in a direction in which the radius of curvature increases or decreases as the link portion 963 moves.

[0080] The link portion 963 protrudes from the outer peripheral surface of the connecting member 94 in the radial direction (upward) of the base member 91. The link portion 963 has a link shaft portion 963a at its tip. The axis of the link shaft portion 963a extends in the left-right direction. The upper end portion of the second linking portion 964 is rotatable around the axis of the link shaft portion 963a relative to the link shaft portion 963a. Note that the link portion 963 rotates around the axis of the base member 91 together with the connecting member 94 when the operating member 95 is operated.

[0081] When the operating member 95 is in the engagement position (a state in which the convex portion 943a of the connecting member 94 is fitted into the first recess 736), the link portion 963 faces diagonally upward toward the front (the state shown in FIG. 7). When the operating member 95 is in the engagement position, the engagement portion 961 is inserted into the engagement recess 44. The state in which the operating member 95 is in the engagement position and the engagement portion 961 is inserted into the engagement recess 44 is referred to as the locked state.

[0082] 10 and 11, when the operating member 95 is in the disengaged position (a state in which the convex portion 943a of the connecting member 94 is fitted into the second recessed portion 737), the link portion 963 (see FIG. 7) faces rearward compared to the engaged position. When the operating member 95 is in the disengaged position, the second linking portion 964 undergoes elastic deformation, specifically, compressive deformation so that the radius of curvature is reduced compared to when the operating member 95 is in the engaged position. As a result, a biasing force (return force) in a direction that causes the engaging portion 961 to come out of the engaging recessed portion 44 is stored in the second linking portion 964 (the state shown in FIG. 10). A state in which the operating member 95 is in the disengaged position and a biasing force (returning force) that causes the engaging portion 961 to come out of the engaging recess 44 is stored in the second linkage portion 964 is referred to as a reserved state. As shown in FIG. 11 , in the reserved state, the biasing force of the compression coil spring 61 biases the rotating member 38 in a direction in which the backrest 20 returns to its initial state in the second direction Y (one side in the second direction Y), so that the engaging portion 961 is sandwiched between the inner surface (lower surface 383 a) of the hole 383 and the inner surface (upper surface 44 a) of the engaging recess 44. That is, in the reserved state, the movement of the engaging portion 961 in the direction in which it comes out of the engaging recess 44 (one side in the first direction X) is restricted by a frictional force resulting from a shear load in the second direction Y acting from the lower surface 383 a of the hole 383 and the upper surface 44 a of the engaging recess 44. In this state, the first linkage portion 96a attempts to rotate around the shaft portion 962 to one side in the first direction X, but is unable to rotate due to the frictional force acting on the engagement portion 961 due to the shear load in the second direction Y. In other words, the first linkage portion 96a elastically deforms into a convex arc shape toward one side in the first direction X between the shaft portion 962 and the engagement portion 961. In other words, a biasing force that causes the engagement portion 961 to come out of the engagement recess 961 is stored in the first linkage portion 96a together with the second linkage portion 964.

[0083] Furthermore, a state in which the operating member 95 is in the disengaged position and the engaging portion 961 has come out of the engaging recess 44 is referred to as an unlocked state. The unlocked state is entered by tilting the backrest 20 backward after the reserved state. That is, as shown in FIG. 12, by tilting the backrest 20 backward, the lower surface 383a of the hole 383 moves away from the engaging portion 961, and the shear load acting on the engaging portion 961 is released (or reduced). As a result, as shown in FIG. 13, the engaging member 96 rotates around the shaft 962 due to the biasing force of the second linkage portion 964, and the engaging portion 961 moves to one side in the first direction X. As a result, the engaging portion 961 comes out of the engaging recess 44, entering the unlocked state. At this time, the biasing force stored in the first linkage portion 96a is also released (by restoration deformation), allowing the engaging portion 961 to quickly disengage from the engaging recess 44.

[0084] In this way, the protrusion 943a of the connecting member 94 fits into the first recess 736, thereby holding the operating member 95 in the engaged position and maintaining the engaging member 96 in the locked state. Furthermore, the protrusion 943a of the connecting member 94 fits into the second recess 737, thereby holding the operating member 95 in the disengaged position and maintaining the engaging member 96 in the reserved state or the unlocked state. In other words, the first recess 736 and the second recess 737 are holding parts that hold the engaging part 961 in the locked state or the unlocked state, respectively.

[0085] The following describes the operation of the engaging member 96 when it transitions from the locked state to the unlocked state. First, in the locked state, as shown in Figures 10 and 11, the convex portion 943a of the connecting member 94 fits into the first recess 736, thereby maintaining the engaging portion 961 inserted into the engaging recess 44 through the hole 383. In this state, the engaging portion 961 prevents the backrest 20 from returning to its initial state.

[0086] To transition the engaging member 96 to the unlocked state, the operating lever 952 is operated to rotate the operating member 95 to the disengaged position. Then, the convex portion 943a moves rearward over the convex portion 738 and fits into the second concave portion 737. As the convex portion 943a moves rearward over the convex portion 738, the link portion 963 (see FIG. 7) moves rearward, compressing and deforming the second linking portion 964. As a result, a biasing force (returning force) in a direction that causes the engaging portion 961 to come out of the engaging concave portion 44 is accumulated in the second linking portion 964. However, a frictional force resulting from a shear load in the second direction Y acting from the lower surface 383a of the hole 383 and the upper surface 44a of the engaging concave portion 44 acts on the engaging portion 961, so that the engaging portion 961 maintains its inserted state in the engaging concave portion 44 (reserved state). In the reserved state, the first linkage portion 96a also elastically deforms as the first linkage portion 96a attempts to rotate about the shaft portion 962 while maintaining the state in which the engagement portion 961 is inserted into the engagement recess 44. Therefore, in the reserved state, a biasing force in the direction of disengaging the engagement portion 961 from the engagement recess 44 is also stored in the first linkage portion 96a.

[0087] 12, in the reserved state, the backrest 20 is tilted backward. Then, the rotating member 38 moves toward the other side of the second direction Y (the direction of arrow C) against the biasing force of the compression coil spring 61. As a result, the lower surface 383a of the hole 383 moves away from the engaging portion 961, thereby releasing (or reducing) the shear load acting on the engaging portion 961. Note that when the backrest 20 is tilted backward, as long as the shear load acting on the engaging portion 961 is less than the biasing force of the second linkage portion 964, the engaging portion 961 may be separated from or in contact with the hole 383 and the engaging recess 44.

[0088] 13, when the shear load acting on the engaging portion 961 is released, the engaging member 96 rotates around the shaft portion 962 due to the biasing force of the second linkage portion 964. As a result, the engaging portion 961 moves in a direction (see arrow D) to come out of the engaging recess 44 as the first linkage portion 96a is displaced to one side in the first direction X. Furthermore, the first linkage portion 96a undergoes restoring deformation, which promotes the movement of the engaging portion 961. As a result, the engaging portion 961 disengages from the engaging recess 44 (unlocked state). Here, in the process of transitioning from the reserved state to the unlocked state, the engaging portion 961 moves along the guide groove 384. This allows the engaging portion 961 to be smoothly released from the engaging recess 44.

[0089] In the unlocked state, the rotation member 38 and the support base body 41 are allowed to move relative to each other in the second direction Y. Therefore, by pressing the rotation member 38 against the bias of the compression coil spring 61, the rotation member 38 is displaced in the second direction Y relative to the support base body 41. As a result, the backrest 20 can be freely reclined between the initial state and the tilted state.

[0090] Next, a description will be given of the operation of the engaging member 96 transitioning from the disengaged state to the locked state. In the following description, the state will be described first in which the hole 383 and the engaging recess 44 do not overlap when viewed from the first direction X, as shown in FIG. As shown in FIG. 14, to transition the engaging member 96 to the locked state, the operating lever 952 is operated to rotate the operating member 95 toward the engaged position. Then, the convex portion 943a moves forward over the convex portion 738 and fits into the first concave portion 736. As the convex portion 943a moves backward over the convex portion 738, the link portion 963 (see FIG. 7) is positioned forward. The link portion 963 being positioned forward restores the compressive deformation of the second link portion 964. By restoring and deforming the second link portion 964, a biasing force acts on the second link portion 964 and the first link portion 96a, urging the engaging portion 961 into the engaging concave portion 44. This causes the engaging member 96 to rotate about the shaft portion 962 so that the engaging portion 961 moves toward the engaging concave portion 44. However, when the hole 383 does not overlap any of the engagement recesses 44 when viewed from the first direction X, the engagement portion 961 comes into contact with a portion of the bottom plate 411 that is located between adjacent engagement recesses 44. As a result, the engagement member 96 does not transition to the locked state. In this state, the first linkage portion 96a elastically deforms, warping to one side in the first direction X as it moves toward the tip end (the end on the engagement portion 961 side). As a result, a biasing force in the direction that inserts the engagement portion 961 into the engagement recess 44 is stored in the first linkage portion 96a.

[0091] The backrest 20 is tilted from the state shown in FIG. 14 (in this embodiment, tilted in a direction returning to the initial position). This causes the hole 383 and the engagement recess 44 to overlap when viewed from the first direction X. The engagement portion 961 then enters the engagement recess 44 due to the biasing forces of the first linkage portion 96a and the second linkage portion 964. Here, in the process of transitioning from the unlocked state to the locked state, the engagement portion 961 moves along the guide groove 384. This allows the engagement portion 961 to smoothly enter the engagement recess 44.

[0092] In the locked state, the engaging portion 961 is disposed across the hole 383 and the engaging recess 44. This restricts relative movement in the second direction Y between the backrest 20 (rotating member 38) and the support base body 41. By selecting one of the multiple engaging recesses 44 into which the engaging portion 961 is to be inserted, the backrest 20 can be stopped (locked) in a predetermined tilted state (reclining position).

[0093] As described above, in this embodiment, the rotating member 38 is biased toward one side in the second direction Y by the biasing force of the compression coil spring 61, so that in the locked state, the engaging portion 961 is sandwiched in the second direction Y by the inner surface of the hole 383 and the inner surface of the engaging recess 44. As a result, movement of the engaging portion 961 in a direction away from the engaging recess 44 is restricted by a frictional force caused by a shear load in the second direction Y acting on the inner surface of the hole 383 and the inner surface of the engaging recess 44. As a result, in the locked state, the first linkage portion 96a and the second linkage portion 964 are elastically deformed; specifically, the first linkage portion 96a is elastically deformed with the shaft portion 962 as a fulcrum, and the second linkage portion 964 is elastically deformed so that its radius of curvature is reduced compared to when it is in the engaged position, so that the first linkage portion 96a and the second linkage portion 964 can accumulate a biasing force that disengages the engaging portion 961 from the engaging recess 44. In this state, by moving the pivoting member 38 and the support base body 41 in the second direction Y against the biasing force of the compression coil spring 61, the engaging portion 961 can be disengaged from the engaging recess 44 by the biasing force stored in the first linking portion 96a and the second linking portion 964. In this way, a biasing force can be stored in the first linkage portion 96a and the second linkage portion 964 by the shear load acting on the engagement portion 961 from the hole portion 383 and the engagement recess 44, and the stored biasing force causes the engagement portion 961 to disengage from the engagement recess 44. This reduces design restrictions on the rotating member 38, the support base body portion 41, and other components located in the vicinity thereof. This simplifies the configuration of the locking mechanism 90, and also prevents loss of design freedom.

[0094] In this embodiment, the engaging member 96 has an axis 962 supported by the rotating member 38 so as to be rotatable around an axis along the left-right direction, and the engaging portion 961 is configured to engage with or disengage from the engaging recess 44 as the engaging member 96 rotates around the axis 962. This configuration allows stable deformation of the engaging member 96. Furthermore, the amount of displacement of the engaging portion 961 can be adjusted appropriately depending on the position of the shaft portion 962 on the engaging member 96.

[0095] In this embodiment, the engaging member 96 is formed in the shape of a leaf spring. This allows for a simple shape of the engaging member 96. Furthermore, by making the engaging member 96 in the shape of a leaf spring, the engaging member 96 can be placed in a relatively narrow space, and the engaging member 96 can be placed without affecting the shapes of the rotating member 38, the support base body 41, and other members positioned around them.

[0096] In this embodiment, the second linking portion 964 is formed in a convex arc shape (curved shape) in the direction in which the engaging portion 961 engages with the engaging recess 44. Therefore, the second linkage portion 964 can be compressively deformed in a direction that reduces the radius of curvature, thereby storing a biasing force in the biasing force storage portion. The biasing force stored by the compressive deformation of the second linkage portion 964 tends to function as a biasing force in a direction that disengages the engagement portion 961 from the engagement recess 44. This allows the engagement portion 961 to smoothly disengage from the engagement recess 44 when the shear load acting on the engagement portion 961 from the hole portion 383 and the engagement recess 44 is released.

[0097] In this embodiment, the configuration is provided with holding portions (first recess 736 and second recess 737) that hold the convex portion 943a of the connecting member 94 at the engaged position or the disengaged position. According to this configuration, the convex portion of the connecting member 94 can be easily and reliably maintained in the disengaged position or the engaged position, thereby improving the operability of the locking mechanism 90.

[0098] A plurality of engagement recesses 44 are provided side by side in the second direction Y. This allows the relative position of the rotating member 38 and the support base body 41 in the second direction Y (the reclining position of the backrest 20) to be adjusted in stages.

[0099] The chair 1 of this embodiment is provided with the locking mechanism 90 described above, and therefore it is possible to provide a chair 1 that can be restricted in a predetermined tilting state while simplifying the configuration and not impairing the degree of freedom in design.

[0100] In this embodiment, an accommodation groove 381a in which the restricting member 96 is disposed is formed between the rear wall 381 and the support member 73. Therefore, it is possible to ensure a space for disposing the engaging member 96 while suppressing interference between the engaging member 96 and the compression coil spring 61.

[0101] Although the embodiment of the chair according to the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate within the scope of the gist of the present invention. For example, in the above embodiment, the locking mechanism 90 according to the present invention is used in the reclining mechanism of the backrest 20 of the chair 1, but this configuration is not limiting. The locking mechanism may be used in other configurations of the chair 1 (for example, the sliding mechanism of the seat 17), or in products other than the chair 1 (for example, the lifting mechanism or sliding mechanism of a furniture piece with a top). In this case, the first member and the second member can be applied as two members that are provided so as to be movable relative to each other.

[0102] In the above-described embodiment, the compression coil spring 61 that returns the backrest 20 to its initial state is used as the biasing member, but this is not limiting. A biasing member separate from the compression coil spring 61 may also be provided. In the above-described embodiment, the engaging member 96 is formed in the shape of a leaf spring, but the engaging member 96 may be formed of an elastically deformable linear member. Also, the engaging member 96 may use a coil spring or the like in the energy storage portion, and the energy storage portion and the engaging portion may be connected by a material that is less likely to deform elastically. In the above-described embodiment, the engaging member 96 is held in the locked state or the unlocked state by holding the convex portion 943a of the connecting member 94 in the engaged position or the disengaged position, but the present invention is not limited to this configuration. For example, the engaging member 96 may be constantly biased toward the locked state and be operable toward the unlocked state. In the above-described embodiment, both the first linking portion 96a and the second linking portion 964, which are connected in both the upper and lower directions of the shaft portion 962, are configured to be elastically deformable, but it is also possible for only one of the linking portions to be elastically deformable. In the above-described embodiment, the shaft portion 962 is provided in the middle portion of the engaging member 96 in the extension direction, but the present invention is not limited to this configuration. The shaft portion 962 may be located at the end of the engaging member 96 on the opposite side to the engaging portion 961.

[0103] In the above-described embodiment, the base member is a shaft portion having a second axis extending in the left-right direction, and the operating shaft 81 and the operating shaft 951 are arranged coaxially on the second axis, but they may also be arranged with their axes offset. The operating shafts 81 and 951 may be configured to be operable by sliding in addition to rotating. [Explanation of symbols]

[0104] 1 chair 20 Backrest 23 Backrest body 30 Backrest support member 38 Rotating member (first member) 40 base 41 Support base body (second member) 44 Engagement recess (second engagement hole) 61 Compression coil spring (biasing member) 73 Support member (base part) 90 Locking mechanism 94 Connection member (operation part) 95 Operating member (operating part) 96 Engagement member (regulation member) 96a First linkage section (energy storage section) 381 Back wall 381a Storage groove (storage space) 383 Hole portion of rotating member (first engagement hole) 736 First recess (retaining portion) 737 Second recess (retaining part) 961 Engagement part (engagement part) 962 Shaft part (support part, energy storage part) 964 Second Linkage Unit (Energy Storage Unit)

Claims

1. A first member; a second member disposed so as to overlap the first member when viewed from a first direction and movable relative to the first member in a second direction intersecting the first direction; a biasing member interposed between the first member and the second member and biasing the first member toward one side in the second direction; a restricting member that is displaceable between a locked state that restricts relative movement between the first member and the second member in the second direction and an unlocked state that allows relative movement between the first member and the second member in the second direction; an operating unit for operating the restricting member, The regulating member is an engaging portion that engages with a second engaging hole formed in the second member through a first engaging hole formed in the first member in the locked state, and disengages from the second engaging hole in the unlocked state; a support portion supported by the first member so as to be rotatable about an axis along a third direction intersecting the second direction when viewed from the first direction; a leaf spring-like energy storage portion that connects at least the engaging portion and the support portion in the extending direction of the regulating member, and that is elastically deformed by operation of the operating portion to store an urging force in a direction in which the engaging portion disengages from the second engaging hole, The locking mechanism is configured so that the engaging portion can be engaged with and disengaged from the second engaging hole as the restricting member rotates around the support portion.

2. The locking mechanism according to claim 1 , wherein the energy storage portion is formed in a convex arc shape in a direction in which the engaging portion engages with the second engaging hole.

3. the operating portion is movable between a disengagement position where the engaging portion deforms the storage portion in a direction to disengage from the second engagement hole and an engagement position where the engaging portion deforms the storage portion in a direction to engage with the second engagement hole, The locking mechanism according to claim 1 or 2, further comprising a holding portion for holding the operating portion at each of the disengaged position and the engaged position.

4. The locking mechanism according to claim 1 , wherein a plurality of second engagement holes are arranged in the second direction.

5. A locking mechanism according to any one of claims 1 to 4, a backrest including the first member; A chair comprising: a base including the second member and rotatably supporting the backrest.

6. The backrest is A backrest body that supports the back of a seated person; a backrest support member that supports the backrest body, the backrest support member has a rear wall provided with a base portion that supports a rear end portion of the biasing member, The chair according to claim 5, wherein a storage space in which the restricting member is disposed is formed between the rear wall and the base portion.

Images