Lumbar support support device and chair

Abstract

To reduce the number of components, reduce an influence of deformation or the like of a lumbar support, and enhance operational feeling when the lumbar support is moved to slide in a vertical direction.SOLUTION: A lumber support support device 100 includes: a right and left pair of attachment members 140; a lumbar support body 51; and a lumbar support support end portion 110 supported by each of the attachment members 140. The attachment members include a back-facing contact surface 143 covering a front of the lumbar support support end portion and extending in the vertical direction. The lumbar support support end portion includes a front-facing contact surface 113 that contacts the back-facing contact surface from back. The back-facing contact surface and the front-facing contact surface form vertical direction relative position regulation means capable of regulating a relative position in the vertical direction between the attachment member and the lumbar support support end portion to support the lumbar support support end portion to the attachment members so as to be vertically movable.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a lumbar support device and a technique suitable for use in a chair. [Background technology]

[0002] Conventionally, a lumbar support that supports the lower back of a seated person is attached to the back of a chair so that it can be moved up and down. However, the height of the seated person's lower back and the position at which they want to be supported vary from person to person. For this reason, most lumbar supports are designed to be adjustable in the vertical direction relative to the backrest body. (For example, see Patent Documents 1 and 2).

[0003] In the inventions described in Patent Documents 1 and 2, the lumbar support supported by the left and right side frames of the backrest frame is configured to be vertically movable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-094287 A [Patent Document 2] JP 2017-079897 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional structures described in Patent Documents 1 and 2, there was a demand for reliable support of the lumbar support while at the same time improving the operability when sliding the lumbar support up and down and making height adjustments smoother. There was also a demand to reduce the number of parts. In particular, there has been a demand for reducing the effects of deformation, etc., in the supporting portion of the lumbar support when a load is applied backward from a seated occupant.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to achieve the objective of improving operational stability and design by making the engagement recesses invisible in front of a chair equipped with a lumbar support device, while reducing the number of parts and improving the feel when sliding the lumbar support up and down. [Means for solving the problem]

[0007] (1) A lumbar support device according to one aspect of the present invention is A pair of left and right mounting members; A lumbar support body extending in the left-right direction between the pair of left and right mounting members; Lumbar support support ends supported by the pair of left and right mounting members at both left and right end positions of the lumbar support body; A lumbar support device comprising: The mounting member includes a rearward abutment surface that covers a front portion of the lumbar support end portion and extends in a vertical direction, The lumbar support support end portion includes a front contact surface that contacts the rear contact surface from behind, The rearward contact surface and the forward contact surface constitute a vertical relative position regulating means that can regulate the relative position in the vertical direction between the mounting member and the lumbar support end, and the vertical relative position regulating means supports the lumbar support end on the mounting member so that it can move up and down by contacting the rearward contact surface and the forward contact surface with each other. This has solved the above problem.

[0008] According to the above configuration, the vertical relative position regulating means supports the lumbar support support end so that it does not move up and down relative to the mounting member when the user is normally seated, by bringing the forward abutment surface of the lumbar support support end into contact with the rearward abutment surface of the mounting member, and when attempting to change the height position of the lumbar support, the lumbar support support end can be moved smoothly up and down relative to the mounting member.

[0009] In addition, since the forward contact surface of the lumbar support end is in contact with the rearward contact surface of the mounting member, even if deformation occurs in the support portion of the lumbar support when a rearward load is applied to the lumbar support by a seated person or the like, the influence of the deformation can be reduced, and a reliable support state in which the up and down position is maintained can be maintained, and the occurrence of factors impeding smooth up and down movement can be reduced. Moreover, since the mounting member can keep the front of the lumbar support end covering the front, the influence from the front on the lumbar support device attached to a chair or the like can be reduced, enabling the function to be maintained, and the design of the surface shape of the backrest can be maintained when the lumbar support device is attached to the backrest of the chair.

[0010] Here, the vertical relative position regulating means can be configured to have an engaging protrusion and a recess on the rearward abutment surface and the forward abutment surface that can engage with and disengage from each other, and by engaging and disengaging with each other, the vertical position of the lumbar support support end relative to the mounting member can be maintained and changed. Furthermore, the vertical relative position regulating means can be configured so that the rearward abutment surface and the forward abutment surface have curved surfaces of different curvatures and abut or are close to each other, and the rearward abutment surface and the forward abutment surface press or reduce pressure or increase or decrease friction between them, thereby maintaining or changing the vertical position of the support end of the lumbar support relative to the mounting member, in other words, so as to regulate the vertical movement of the lumbar support by sliding resistance (frictional force).

[0011] In addition, the lumbar support end portion can be designed so that its height dimension in the up-down direction is greater than its thickness dimension in the front-rear direction when viewed from the left-right direction. This can increase the rigidity of the lumbar support end portion against vertical forces. Therefore, when moving the lumbar support in the up-down direction, if an operator applies a vertical force, the deformation of the lumbar support end portion in the up-down direction is suppressed. In this respect, too, the operability when sliding the lumbar support in the up-down direction can be improved.

[0012] (2) The lumbar support device of the present invention, in the above (1), The lumbar support end portion includes a rearward restricting surface facing the forward contact surface, The mounting member includes a forward restriction surface facing the rearward restriction surface, the rearward restriction surface and the forward restriction surface constitute a front-rear direction position restriction means that can restrict the positions of the mounting member and the lumbar support end portion in the front-rear direction, The front-rear direction position restriction means restricts the position in the front-rear direction by contacting the rearward restriction surface and the forward restriction surface with each other. It is possible.

[0013] According to the above configuration, the rearward restricting surface of the lumbar support support end and the forward restricting surface of the mounting member always contact each other, or contact each other when a rearward load is applied to the lumbar support by a seated person or the like, so that the positions of the lumbar support support end and the mounting member in the front-rear direction can be maintained without changing. This makes it easy to maintain the contact state between the forward abutting surface of the lumbar support support end and the rearward abutting surface of the mounting member. Therefore, even if deformation occurs in the support part of the lumbar support when a rearward load is applied to the lumbar support by a seated person or the like, it is possible to reduce the influence of the deformation, maintain a reliable support state in which the vertical position is maintained, and reduce the occurrence of factors that hinder smooth vertical movement. Furthermore, since the vertical relative position regulating means and the front-rear position regulating means can be formed by the lumbar support supporting end portion and the mounting member, the number of parts can be reduced.

[0014] (3) The lumbar support device of the present invention, in the above (2), the forward restriction surface is located rearward of the rearward restriction surface, the rearward abutment surface is located rearward of the forward restriction surface, and the forward abutment surface is located rearward of the rearward abutment surface, It is possible.

[0015] According to the above configuration, when a rearward load is applied to the lumbar support, even if the lumbar support support end is displaced rearward, the rearward restricting surface does not come into contact with the forward restricting surface, and the displacement is not increased. This makes it possible to maintain the position of the lumbar support support end and the mounting member in the front-rear direction unchanged. This makes it easy to maintain the contact state between the forward contact surface of the lumbar support support end and the rearward contact surface of the mounting member. Furthermore, by positioning the rearward regulating surface and the forward regulating surface forward of the forward regulating surface and the rearward abutment surface, it is possible to reduce the effects of displacement of the lumbar support support end compared to when the rearward regulating surface and the forward regulating surface are positioned rearward of the forward regulating surface and the rearward abutment surface.

[0016] (4) The lumbar support device of the present invention, in the above (3), The lumbar support end portion has an inward surface that connects the forward contact surface and the rearward restriction surface on the outer side in the left-right direction, The mounting member has an outward surface facing the inward surface, the inward surface and the outward surface constitute a left-right direction position restricting means for restricting the left-right direction positions of the mounting member and the lumbar support end portion, The left-right direction position restriction means restricts the left-right direction positions of the mounting member and the lumbar support end portion by contacting the inward surface and the outward surface with each other. It is possible.

[0017] According to the above-mentioned configuration, the inward surface and the outward surface come into contact with each other, so that the left and right mounting members can press the lumbar support end portions located at both ends of the lumbar support from the outside, thereby preventing the lumbar support end portions from being displaced in the left-right direction relative to the mounting members. Furthermore, since the vertical relative position regulating means, the front-rear position regulating means and the left-right position regulating means can be constituted by the lumbar support supporting end portion and the mounting member, the number of parts can be reduced. Moreover, in this state, while maintaining the positional restriction between the mounting member and the support end of the lumbar support in the front-rear direction, the support position and smooth vertical movement of the mounting member and the support end of the lumbar support in the up-down direction can be achieved. Also, the posture of the lumbar support can be maintained while smooth vertical movement can be achieved.

[0018] (5) The lumbar support device of the present invention, in the above (4), the mounting member is provided with an engaging outward protrusion having the forward restricting surface, the rearward abutting surface, and the outward surface, The lumbar support support end portion is provided with an engaging inward protrusion having the rearward restricting surface and the inward surface forward of the forward contact surface, the engaging outward convex portion and the engaging inward convex portion are movable relative to each other in the up-down direction while being engaged with each other in the left-right direction, It is possible.

[0019] According to the above configuration, the inwardly facing engaging convex portion of the lumbar support support end facing inward can be kept overlapping with the outwardly facing engaging convex portion of the mounting member when viewed from the front-rear direction. In other words, the inwardly facing engaging convex portion of the lumbar support support end can be kept engaged with the outwardly facing engaging convex portion of the mounting member. This reliably prevents relative displacement in the left-right direction between the mounting member and the lumbar support support end. Furthermore, it is easy to maintain the posture of the lumbar support, such as preventing left-right tilting or front-rear position displacement with respect to the lumbar support. Here, since the tip of the engaging inward convexity faces inward, when a rearward load is applied to the lumbar support, even if the tip of the engaging inward convexity is displaced, it will not come off from the engaging inward convexity.

[0020] Furthermore, the engaging outward convex portion can be formed of one side wall of a groove portion that is formed in the mounting member and extends in the up-down direction. The groove portion opens outward in the left-right direction, and the other side wall portion is located forward of the engaging inward convex portion, and this other side wall portion can cover the lumbar support end portion from the front. In this case, the one side wall portion can have a plurality of recesses spaced apart in the up-down direction. Also, by configuring the engaging outward protrusion as a groove, the mounting member can easily cover the lumbar support end portion from the front side and can be maintained in this state regardless of the left-right dimension of the one side wall portion.

[0021] The engaging inward protrusion may be formed in an L-shape with the tip bent inwardly and protruding forward from the end of the lumbar support end. In this case, one L-shaped engaging inward protrusion may be formed on one end of the lumbar support end. Alternatively, a plurality of L-shaped engaging inward protrusions may be disposed in the up-down direction at one end of the lumbar support end. When a plurality of L-shaped engaging inward protrusions are provided at one end of the lumbar support end, they may be disposed spaced apart from each other in the up-down direction.

[0022] (6) The lumbar support device of the present invention, in the above (5), The vertical relative position regulation means is an engagement protrusion formed on the front contact surface and protruding forward; a recess formed on the rear contact surface, the recess opening rearward and engaging with the engaging protrusion; having A plurality of the recesses are arranged in the vertical direction. It is possible.

[0023] According to the above configuration, the height position of the lumbar support end relative to the mounting member can be set to the selected position by engaging the engaging protrusion with the selected recess. Moreover, by maintaining the engagement of the engaging protrusion with the recess, the height position of the lumbar support end relative to the mounting member does not fluctuate. This increases the restraining force against the vertical movement of the lumbar support. Furthermore, by engaging the engaging protrusion with a recess at a different height, the height position of the supporting end of the lumbar support relative to the mounting member can be easily set to the appropriate position. Furthermore, by releasing the engagement of the engagement protrusion from the recess, the height position of the lumbar support end portion relative to the mounting member can be changed from the specified position.

[0024] The lumbar support device of the present invention is The vertical relative position regulation means is an engagement protrusion formed on the rear contact surface and protruding rearward; a recess formed on the front contact surface, the recess opening forward and engaging with the engaging protrusion; having A plurality of the recesses may be arranged in the vertical direction.

[0025] (7) The lumbar support device of the present invention, in the above (6), The engaging inward convex portion is divided into upper and lower portions spaced apart from each other, and the engaging protrusion portion is disposed between the engaging inward convex portions in the vertical direction. It is possible.

[0026] According to the above-mentioned configuration, it is possible to maintain a state in which the engaging protrusion, which determines the vertical position of the lumbar support end relative to the mounting member, is prevented from displacing in the front-rear direction by the engaging inward protrusions on both vertical sides of the engaging protrusion. This makes it easy to prevent the engaging protrusion from coming off the recess with which it is engaged. Furthermore, by forming the engaging inward convex portions on the upper and lower ends of the lumbar support support end, it is possible to easily prevent the lumbar support from becoming tilted relative to the left and right mounting members in all cases, such as when a twisting displacement occurs in the lumbar support in the front-to-back direction, or when a twisting displacement occurs in the lumbar support in the up-to-down direction, or when a twisting displacement occurs in the lumbar support in the left-to-right direction.

[0027] (8) The lumbar support device of the present invention, in the above (7), A groove is formed around the engagement protrusion to form an engagement displacement portion that allows the engagement protrusion to be displaced in the front-rear direction, and the engagement displacement portion has a base portion on the inner side in the left-right direction that does not displace in the front-rear direction. It is possible.

[0028] According to the above configuration, the engagement displacement portion is formed to be elastically deformable, which facilitates engagement of the engagement protrusion with the recess, and allows smooth setting of the vertical position of the lumbar support relative to the mounting member. Also, the engagement displacement portion is formed to facilitate disengagement of the engagement protrusion from the recess, allowing smooth adjustment of the vertical position of the lumbar support relative to the mounting member.

[0029] Here, when the L-shaped engaging inward convex parts are formed at both the top and bottom of the engaging protrusion, they can be arranged so that the contour of the engaging inward convex parts does not overlap the contour of the engaging displacement part when viewed from the front, or in this case, they can be arranged so that the contour of the engaging inward convex parts when viewed from the front overlaps the contour of the engaging displacement part at the top and bottom ends. Furthermore, the contour of the engaging inward protrusion when viewed from the front can be arranged to overlap the engaging protrusion. In this case, the engaging inward protrusion may or may not be divided in the up-down direction.

[0030] Also, the engaging displacement portion that allows the engaging protrusion to be displaced in the front-rear direction may be formed by a reduced thickness portion that is formed around the engaging protrusion and has a smaller dimension in the front-rear direction, rather than a groove. Alternatively, the engaging displacement portion that allows the engaging protrusion to be displaced in the front-rear direction may be engaged by a bridge portion that is formed around the engaging protrusion, rather than a groove. In these cases, the configuration is not limited as long as the engaging protrusion can be displaced in the front-rear direction to the extent that it can be removed from the recess.

[0031] (9) The lumbar support device of the present invention is the above-mentioned (8), The lumbar support end portion has an insertion recess extending from the outside to the inside in the left-right direction, the insertion recess being formed at a rear position of the engagement displacement portion, The gripping member is inserted into the insertion recess in a state where it protrudes outward in the left-right direction from the insertion recess. It is possible.

[0032] According to the above-mentioned configuration, the gripping member is inserted into the insertion recess that opens on the left and right outside in a state where it protrudes outward in the left and right direction, so that the gripping member protrudes outward in the left and right direction from the lumbar support support end. This makes it easy to operate the lumbar support up and down by operating the gripping member from the outside, thereby setting the up and down position of the lumbar support. In addition, the lumbar support body is prevented from being bent by the force applied to the grip member in order to move the lumbar support in the vertical direction, which improves the operational feel when sliding the lumbar support in the vertical direction.

[0033] Furthermore, the groove forming the engagement displacement portion can be configured to penetrate the insertion recess on the front surface of the insertion recess. This allows the engagement displacement portion to be displaced in the front-rear direction toward the axis of the insertion recess. In this case, the displacement of the engagement displacement portion only needs to be sufficient to displace the engagement projection in the front-rear direction to the extent that it can come out of the recess.

[0034] At the same time, by configuring the gripping member to be inserted into the insertion recess, the gripping member can be maintained in a state of protruding outward in the left-right direction. This makes it possible to easily operate the lumbar support from the outside in the left-right direction without affecting the relative movement state and support state between the mounting member and the lumbar support support end. At the same time, it is possible to improve the ease of assembly between the mounting member and the lumbar support support end.

[0035] In addition, it is preferable that the gripping member has a height dimension in the up-down direction greater than a thickness dimension in the front-rear direction when viewed from the left-right direction. This can increase the rigidity of the gripping member against a force in the up-down direction. Therefore, when the operator applies a force in the up-down direction to move the lumbar support in the up-down direction, the deformation of the gripping member in the up-down direction is suppressed. In this respect, too, the operability when sliding the lumbar support in the up-down direction can be improved.

[0036] (10) The lumbar support device of the present invention is the above-mentioned (9), An allowance recess for allowing the engagement displacement portion to be displaced rearward is formed on the front surface of the gripping member. It is possible.

[0037] According to the above configuration, the allowing recess allows the engaging displacement portion to be displaced in the front-rear direction to an extent that it does not interfere with the gripping member, and therefore the engaging protrusion can be displaced in the front-rear direction to an extent that it can be removed from the recess. This prevents the gripping member and the engaging displacement portion from interfering with each other even when the engaging protrusion is removed from the recess when setting the vertical position of the lumbar support. Therefore, the lumbar support support end portion other than the engaging displacement portion is not displaced backward relative to the mounting member, making it easy to smoothly set the vertical position.

[0038] (11) The lumbar support device of the present invention, in the above (10), A locking portion is formed inside the gripping member and the insertion recess to lock the gripping member to the lumbar support end portion. It is possible.

[0039] According to the above-mentioned configuration, for example, by using a configuration having a locking portion formed of a snap fit, it is possible to assemble the gripping member by simply inserting the gripping member into the insertion recess. This makes it possible to improve the work efficiency in assembling the lumbar support device.

[0040] (12) A chair according to the present invention has a lumbar support device according to any one of (1) to (10) above, The mounting member is attached to the backrest. It is possible.

[0041] According to the above configuration, the lumbar support can be supported by the backrest only by the mounting member. As a result, even if the backrest is deformed when the seated person leans against it, the deformation of the lumbar support device can be suppressed, and the supporting state of the lumbar support can be prevented from being affected, such as the supporting end of the lumbar support coming off the mounting member.

[0042] (13) A chair according to the present invention has the lumbar support device according to (11), The mounting member is attached to the backrest, The gripping member protrudes outward through a through hole formed in the backrest in the left-right direction. It is possible.

[0043] According to the above configuration, the gripping member is inserted into the through-holes that open on the left and right outer sides of the backrest in a state where it protrudes outward in the left and right direction, so that the gripping member protrudes outward in the left and right direction from the backrest. This makes it easy to adjust the up and down position of the lumbar support by operating the gripping member from the outside and moving the lumbar support up and down relative to the backrest. In addition, the lumbar support body is prevented from being bent by the force applied to the grip member in order to move the lumbar support in the vertical direction, which improves the operational feel when sliding the lumbar support in the vertical direction.

[0044] Furthermore, the gripping member is connected to the lumbar support end in the insertion recess through a through hole formed in the sturdy backrest. This restricts the gripping member from displacing in the front-rear direction by the portion connected to the lumbar support end and the portion inserted into the through hole. When operating the operating member, the gripping member is prevented from being deformed in the front-rear direction by the force applied by the operator. In addition, the lumbar support can be supported by the backrest only by the mounting member. As a result, even if the backrest is deformed when the seated person leans against it, deformation of the lumbar support device can be suppressed, and the supporting state of the lumbar support can be prevented from being affected, such as the supporting end of the lumbar support coming off the mounting member.

[0045] (14) The chair of the present invention, in the above (13), A cylindrical guide member is disposed in the through hole, and the gripping member passes through the guide member. It is possible.

[0046] According to the above configuration, an opening of a through hole extending in the left-right direction on the outer side is formed on the outside of the backrest, and the backrest can further include a guide member that is removably attached to this opening and has a guide slit formed therein. According to this configuration, by attaching a guide member having a guide slit formed therein to an opening formed in the outer wall portion of the backrest, a guide slit for inserting a gripping member can be easily provided in the outer wall portion of the backrest. Effect of the Invention

[0047] According to the present invention, it is possible to obtain an effect of improving the operational feel when sliding the lumbar support up and down with a small number of parts. [Brief description of the drawings]

[0048] [Figure 1] 1 is a front view showing an embodiment of a chair according to the present invention. [Diagram 2] 1 is an exploded perspective view showing a backrest and lumbar support device in an embodiment of a chair according to the present invention. FIG. [Diagram 3] 2 is an enlarged perspective view showing a backrest, an attachment member, and a gripping member in an embodiment of a chair according to the present invention. FIG. [Figure 4] 2 is a cross-sectional view showing a backrest, an attachment member, and a lumbar support end portion in an embodiment of a chair according to the present invention. FIG. [Diagram 5] 1 is a horizontal cross-sectional view showing a backrest and a lumbar support device in an embodiment of a chair according to the present invention. [Figure 6] 1A to 1C are horizontal cross-sectional views showing a backrest and a lumbar support device at different heights in an embodiment of a chair according to the present invention. [Figure 7] FIG. 2 is a perspective view showing a mounting member and a lumbar support end in an embodiment of a chair according to the present invention. [Figure 8] FIG. 2 is a perspective view showing a lumbar support end portion in an embodiment of a chair according to the present invention. [Figure 9] FIG. 2 is a front view showing a lumbar support end portion in an embodiment of a chair according to the present invention. [Figure 10] 1 is a vertical cross-sectional view showing a backrest and a lumbar support device in an embodiment of a chair according to the present invention. [Figure 11] FIG. 2 is a perspective view showing a gripping member in an embodiment of a chair according to the present invention. [Figure 12] FIG. 2 is a perspective view showing a guide member in the embodiment of the chair according to the present invention. [Figure 13] FIG. 2 is a perspective view showing a guide member in the embodiment of the chair according to the present invention. [Figure 14] 4 is a vertical cross-sectional view showing an engaging protrusion and a recess in an embodiment of a chair according to the present invention. FIG. [Figure 15] 11 is a cross-sectional view showing another example of a backrest, an attachment member, and a lumbar support end portion in an embodiment of a chair according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a lumbar support device and a chair according to the present invention will be described with reference to the drawings. 1 is a front view showing a chair according to the present embodiment, in which reference numeral 1 denotes a chair.

[0050] The chair according to this embodiment is a piece of furniture that supports a seated person in a seated position, and is used in, for example, offices or stores. The chair according to this embodiment includes legs 2, a base 3, a seat 4, and a backrest 5, as shown in FIG.

[0051] In the following description, for convenience of explanation, the direction seen by a seated person sitting in a normal posture on the seat 4 is defined as the front direction XF of the chair 1. For example, the front side seen by the seated person is defined as the front side of the chair 1. Also, the rear side seen by the seated person is defined as the rear side of the chair 1. The direction connecting the front side and the rear side is defined as the front-rear direction X. In this embodiment, the first side of the front-rear direction X is the front direction XF. The second side of the front-rear direction is the rear direction XB.

[0052] Additionally, the left side as viewed from the seated person is the left side of chair 1. Additionally, the right side as viewed from the seated person is the right side of chair 1. The direction connecting the left and right sides is the left-right direction Y. The first side in the left-right direction Y is the right direction YR. The second side in the left-right direction Y is the left direction YL. As viewed from the seated person, the center side of chair 1 in the left-right direction Y is the inside of the left-right direction Y, and the side away from the center of chair 1 in the left-right direction Y is the outside of the left-right direction Y. Additionally, the upward direction Z as viewed from the seated person is the upper side of chair 1. Additionally, the downward side as viewed from the seated person is the lower side of chair 1. The direction connecting the upper side and the lower side is the up-down direction Z.

[0053] The legs 2 come into contact with the floor surface and directly or indirectly support the base 3, seat 4, and backrest 5 from below. As shown in FIG. 1, the legs 2 have a multi-pronged leg 2a and a leg column 2b. The multi-pronged leg 2a has a plurality of leg bodies 2a1 extending radially from the center. A caster 2a2 is attached to the tip of each leg body 2a1. Each caster 2a2 comes into contact with the floor surface so as to be able to roll.

[0054] The leg 2b is erected at the center of the multi-leg 2a and extends upward from the center of the multi-leg 2a. The leg 2b has an outer tube 2b1 and an inner tube 2b2. The outer tube 2b1 is fixed to the multi-leg 2a. The inner tube 2b2 has a lower part connected to the outer tube 2b1 and is connected to the outer tube 2b1 so as to be movable in the vertical direction. The inner tube 2b2 is supported by a spring (not shown) housed inside the leg 2b. The upper end of the inner tube 2b2 is fixed to the support base 3. The leg 2b supports the seat 4 via the support base 3 so as to be movable in the vertical direction.

[0055] The support base 3 is a box-shaped section located above the legs 2. The support base 3 includes, for example, a lifting mechanism for the seat 4 and a tilting mechanism for the backrest 5 inside. The support base 3 is located below the seat 4 and supports the seat 4 from below. The backrest 5 is connected to the rear of the support base 3. The seat 4 is the section on which a seated person directly sits, and its upper surface is the seating surface. The chair 1 may also include armrests on which the seated person's elbows and arms can be placed. Such armrests are fixed to the sides of the seat 4, for example.

[0056] FIG. 2 is an exploded perspective view showing the backrest and lumbar support device of the chair of the present embodiment, as viewed obliquely from the front. The backrest 5 is a portion that supports a seated person from the rear side. As shown in Fig. 1 and Fig. 2, the backrest 5 includes a connecting member 5a, a backrest main body 5b (see Fig. 1 and Fig. 2), a cover material 5f (see Fig. 1), a cushion material 5c (see Fig. 1), and a lumbar support 50 (see Fig. 2).

[0057] The connecting member 5a is a member for connecting the backrest 5 to the base 3. As shown in FIG. 2, the backrest body 5b receives an input load from the back of the seated person and transmits it to the support base 3 and the legs 2 via the connecting member 5a. The backrest body 5b has a back frame portion 20 and a flexible portion (not shown). The backrest body 5b is an injection molded body formed by, for example, injection molding of resin. Furthermore, the back frame portion 20 may be integrated with the flexible portion. A skin material 5f is stretched on the surface, i.e., the front surface, of the back frame portion 20 as a stretching material. A cushion material 5c may be arranged inside the back frame portion 20 and the skin material 5f.

[0058] The cushion material 5c is provided on the front side of the backrest 5 in the front-rear direction X. The cushion material 5c is arranged in the inner area of ​​the backrest main body 5b surrounded by the back frame portion 20. The cover material 5f forms the outer surface of the backrest 5 with which a person sitting on the backrest comes into contact. The material of the cover material 5f is not particularly limited, and it can be formed of, for example, a cloth material or a leather material. The cover material 5f is provided so as to cover the backrest main body 5b, the back frame portion 20, the cushion material 5c, and the lumbar support 50. Note that the cover material 5f, the cushion material 5c, etc. may not be provided in part or in whole depending on the design of the chair 1, etc.

[0059] The back frame portion 20 is a portion formed in a frame shape when viewed from the front side in the rear direction XB (when viewed from the front). The back frame portion 20 surrounds the flexible portion and the cushioning material 5c, if any, from the circumferential outside. The back frame portion 20 is disposed along the outer periphery of the backrest 5. The back frame portion 20 is formed in a substantially rectangular shape when viewed from the front side. The back frame portion 20 has an upper support frame 20a, a lower support frame 20b, a left support frame (support frame) 20c, and a right support frame (support frame) 20d. Each of the upper support frame 20a, the lower support frame 20b, the left support frame 20c, and the right support frame 20d is a strength member having high rigidity.

[0060] The upper support frame 20a is located at the top of the backrest 5. The upper support frame 20a is a rod-shaped portion extending along the left-right direction. The upper support frame 20a is curved so that both outer sides of the upper support frame 20a protrude in the forward direction XF from the center side of the upper support frame 20a in the left-right direction Y in order to improve the seating comfort of the seated person.

[0061] The lower support frame 20b is located under the backrest 5. The lower support frame 20b is a rod-shaped portion extending in the left-right direction. The lower support frame 20b is set to have a higher strength than the upper support frame 20a. The lower support frame 20b is formed to have a larger diameter and be thicker than the upper support frame 20a. The lower support frame 20b may have a rear wall portion 20b1 erected at a position close to the rear direction XB. The rear wall portion 20b1 may be substantially plate-shaped. Both ends of the rear wall portion 20b1 in the left-right direction Y may be connected to the vicinity of the lower ends of the left support frame 20c and the right support frame 20d, respectively.

[0062] The left support frame 20c is located at the left part of the backrest 5. The left support frame 20c extends along the vertical direction and connects the left end of the upper support frame 20a and the left end of the lower support frame 20b. The right support frame 20d is located at the right part of the backrest 5. The right support frame 20d extends along the vertical direction and connects the right end of the upper support frame 20a and the right end of the lower support frame 20b.

[0063] The left support frame 20c and the right support frame 20d are formed symmetrically to each other on both outer sides in the left and right direction with respect to the center of the chair 1. Each of the left support frame 20c and the right support frame 20d has a front surface (first surface) 20f and an outer wall portion 20w.

[0064] In the left support frame 20c, the front surface 20f is formed facing the forward direction XF (first side in the front-to-rear direction) at a position (outside in the left-to-right direction) close to the contour of the back frame portion 20 in the left direction YL when viewed from the front.

[0065] In the left support frame 20c, the outer wall portion 20w is formed at a lower position of the front surface 20f of the left support frame 20c, protruding toward the front direction XF from a position close to the contour in the left direction YL in a front view. The outer wall portion 20w is formed at the lower part of the left support frame 20c so as to be wider in diameter than the upper part of the left support frame 20c. The outer wall portion 20w is formed to have a height area dimension in the vertical direction Z that corresponds approximately to the height dimension of the rear wall portion 20b1.

[0066] In the right support frame 20d, the front surface 20f and the outer wall portion 20w are formed continuously. Both the front surface 20f and the outer wall portion 20w are formed to have a surface shape consisting of a smoothly curved surface. Both the front surface 20f and the outer wall portion 20w are inclined in the left-right direction Y so that the outer side protrudes in the forward direction XF from the center side of the backrest 5.

[0067] In the right support frame 20d, the front surface 20f is formed facing the forward direction XF (first side in the front-to-rear direction) at a position (outside in the left-to-right direction) close to the contour of the back frame portion 20 in the left direction YL when viewed from the front.

[0068] In the right support frame 20d, the outer wall portion 20w is formed at a lower position of the front surface 20f of the right support frame 20d, protruding toward the front direction XF from a position close to the contour in the left direction YL in a front view. The outer wall portion 20w is formed so as to be wider and larger in diameter at the lower portion of the right support frame 20d than at the upper portion of the right support frame 20d. The outer wall portion 20w is formed to have a height area dimension in the vertical direction Z that corresponds approximately to the height dimension of the rear wall portion 20b1.

[0069] In the right support frame 20d, the front surface 20f and the outer wall portion 20w are formed continuously. Both the front surface 20f and the outer wall portion 20w are formed to have a surface shape consisting of a smoothly curved surface. Both the front surface 20f and the outer wall portion 20w are inclined in the left-right direction Y so that the outer side protrudes in the forward direction XF from the center side of the backrest 5.

[0070] 2, the lumbar support 50 is located below the center of the backrest 5 in the up-down direction Z. The lumbar support 50 extends in the left-right direction Y to support the waist of the seated person. The lumbar support 50 is integrally formed with a lumbar support main body 51 and lumbar support end portions 52 at both ends of the lumbar support main body 51 in the left-right direction Y.

[0071] The lumbar support body 51 is a plate member that supports the waist of a seated person. The lumbar support ends 52 are located at both left and right ends of the lumbar support main body 51, and are formed symmetrically with respect to the center of the chair 1 while continuing from the lumbar support main body 51. The lumbar support main body 51 is disposed on the front side of the backrest 5. The lumbar support main body 51 extends in the left and right direction. The lumbar support main body 51 is formed in a plate shape with the left and right direction as the longitudinal direction. The largest surface of the lumbar support main body 51 faces the forward direction XF.

[0072] The lumbar support end 52 is continuous with the lumbar support main body 51 in the left-right direction Y. The lumbar support end 52 extends outside the lumbar support main body 51 in the left-right direction Y. The lumbar support end 52 is formed in a plate shape whose width dimension in the up-down direction is smaller than that of the lumbar support main body 51. Lumbar support ends 52 at both ends in the left and right direction are each supported by the back frame portion 20. The lumbar support main body 51 is supported by the back frame portion 20 via the lumbar support ends 52. The lumbar support 50 is supported on the back frame portion 20 by a lumbar support device 100.

[0073] FIG. 3 is an enlarged perspective view showing the backrest, the attachment member, and the grip member in this embodiment. FIG. 4 is a cross-sectional view showing the backrest, the attachment member, and the lumbar support end in this embodiment. FIG. 5 is a horizontal cross-sectional view showing the backrest and the lumbar support device in this embodiment. FIG. 6 is a horizontal cross-sectional view showing the backrest and the lumbar support device in this embodiment at a different height from that in FIG. 5. FIG. 7 is a perspective view showing the attachment member and the lumbar support end in this embodiment. FIG. 8 is a perspective view showing the lumbar support end in this embodiment. FIG. 9 is a front view showing the lumbar support end in this embodiment. FIG. 10 is a vertical cross-sectional view showing the backrest and the lumbar support device in this embodiment.

[0074] The lumbar support device 100 includes a lumbar support end portion 110, an attachment member 140, a guide member 160, and an operation member (gripping member) 170. The lumbar support 50 can be moved up and down by operating the operating member 170. Lumbar support end portion 110 is formed at lumbar support end portion 52. Lumbar support end portion 110 is attached to back frame portion 20 with its front side covered by attachment member 140. When attached to back frame portion 20, lumbar support end portion 110 has its front side hidden by attachment member 140.

[0075] The mounting member 140 is attached to the back frame portion 20 of the backrest 5. The mounting member 140 is attached so as to be housed in the mounting recess 20g. The mounting recess 20g is formed in the right support frame 20d. The mounting recess 20g is formed in the surface of the right support frame 20d so as to be recessed in the rear direction XB from the front surface 20f. The mounting recess 20g is formed in a position in the up-down direction Z of the right support frame 20d close to the lower support frame 20b.

[0076] The mounting member 140 includes a front surface 140a, an outwardly facing engagement protrusion 141, a front-facing restricting surface 142, a rearwardly facing abutting surface 143, an outwardly facing surface 144, a rearwardly facing surface 145, a mounting front portion 145A, a recess 146, and a groove portion 148.

[0077] The front surface 140a of the mounting member 140 is formed to be flush with the front surface 20f of the right support frame 20d. The mounting member 140 is fixed to the mounting recess 20g at both ends in the vertical direction Z by connecting means such as bolts. At this time, the mounting member 140 is separated from the front surface 20ga of the mounting recess 20g at the center position in the vertical direction Z, as described later.

[0078] The mounting member 140 covers the front of the lumbar support end portion 110. The mounting member 140 includes an engaging outward protrusion 141 extending in the up-down direction Z. The mounting member 140 includes a front mounting portion 145A extending in the up-down direction Z. The mounting front portion 145A has a front surface 140a on its front side. The mounting front portion 145A has a rearward surface 145 on its rear side. The mounting front portion 145A and the engaging outward protrusion 141 are spaced apart in the front-rear direction X. The mounting front portion 145A and the engaging outward protrusion 141 have a longitudinal direction in the up-down direction Z. The engaging outward protrusion 141 is located in the rear direction XB of the mounting front portion 145A. The mounting front portion 145A and the engaging outward protrusion 141 are arranged in a substantially parallel state. A groove portion 148 is formed between the mounting front portion 145A and the engaging outward protrusion 141 in the front-rear direction X.

[0079] Groove portion 148 opens outward in the left-right direction Y. Groove portion 148 has a bottom that is closed on the inside in the left-right direction Y. Both ends of groove portion 148 in the up-down direction Z are closed by mounting legs 148a and 148b. Both ends of groove portion 148 in the up-down direction Z are connected to mounting legs 148a and 148b.

[0080] The mounting legs 148a and 148b protrude in the rear direction XB beyond the engaging outward convex portion 141. The mounting legs 148a and 148b are connected to a surface of the mounting recess 20g in the rear direction XB. A connecting means such as a bolt may pass through the mounting legs 148a and 148b in the front-rear direction X. The mounting legs 148a are located at the upper end of the mounting member 140. The mounting legs 148b are located at the lower end of the mounting member 140. Both ends of the mounting front portion 145A in the up-down direction Z are connected to the mounting legs 148a and 148b.

[0081] The groove portion 148 extends such that its dimension in the up-down direction Z is greater than its dimension in the left-right direction Y. Both inner surfaces of the groove portion 148 in the front-rear direction X are composed of a rearward surface 145 and a forward-facing restriction surface 142. Between the rearward surface 145 and the forward-facing restriction surface 142 in the front-rear direction X, the groove portion 148 is formed. The rearward surface 145 and the forward-facing restriction surface 142 face each other in the front-rear direction X. Both the rearward surface 145 and the forward-facing restriction surface 142 are surfaces that extend approximately along the YZ direction. The rearward surface 145 and the forward-facing restriction surface 142 are disposed approximately parallel to each other.

[0082] The front restriction surface 142 is formed in the front direction XF of the engaging outward convex portion 141. The front restriction surface 142 extends in the up-down direction Z as its longitudinal direction. The width dimension of the front restriction surface 142 in the left-right direction Y is smaller than the width dimension of the rearward surface 145 in the left-right direction Y. The front restriction surface 142 is positioned shifted inward from the rearward surface 145 in the left-right direction Y. The mounting member 140 has a rearward surface 145 facing the forward restriction surface 142 at a position in the forward direction XF of the forward restriction surface 142. The rearward surface 145 extends with the vertical direction Z as its longitudinal direction. The rearward surface 145 faces a forward surface 115 described later.

[0083] The engaging outward protrusion 141 has a front-facing restriction surface 142, a rear-facing abutment surface 143, and an outward surface 144. The front side of the engaging outward protrusion 141 in the front-rear direction X is the front-facing restriction surface 142. The rear side of the engaging outward protrusion 141 in the front-rear direction X is the rearward abutment surface 143. The outside of the engaging outward protrusion 141 in the left-right direction Y is the outward surface 144. Both ends of the engaging outward protrusion 141 in the up-down direction Z are connected to the mounting legs 148a and 148b.

[0084] In the front-rear direction X, the thickness dimension of the engaging outward protrusion 141 is smaller than the thickness dimension of the mounting front portion 145A. The strength of the mounting member 140 in the front-rear direction X is ensured by the engaging outward protrusion 141, the mounting front portion 145A, the bottom of the groove portion 148 that connects them in the front-rear direction X, and the mounting legs 148a and 148b that connect them at their ends in the up-down direction Z.

[0085] The rearward abutment surface 143 is approximately parallel to the frontward restricting surface 142. The thickness dimension of the engaging outward protrusion 141 in the front-rear direction X is approximately uniform. The rearward abutment surface 143 extends with the vertical direction Z as its longitudinal direction. The rearward abutment surface 143 is a surface that is approximately along the YZ direction. The dimension of the rearward abutment surface 143 in the vertical direction Z is approximately equal to the dimension of the engaging outward protrusion 141 in the vertical direction Z. The front-rear direction X dimension of the rearward abutment surface 143 is approximately equal over the entire length in the vertical direction Z. A plurality of recesses 146 are formed in the rearward abutment surface 143. The recesses 146 are disposed spaced apart from one another in the up-down direction Z. All of the recesses 146 are recessed in the forward direction XF further than the rearward abutment surface 143. All of the recesses 146 have the same shape. The rearward abutment surface 143 is in contact with or as close to a forward abutment surface 113 (described later) as it is in contact with the frontward abutment surface 113.

[0086] The recess 146 is formed in the rearward abutment surface 143 and opens in the rear direction XB. The recess 146 engages with an engagement protrusion 116, which will be described later. The recess 146 is shaped to allow the engagement protrusion 116, which will be described later, to move in the up-down direction Z. The recess 146 is formed such that an end portion in the up-down direction Z is smoothly recessed from the rearward abutment surface 143. The end portion in the up-down direction Z of the recess 146 is formed from a curved surface that is inclined in the up-down direction Z.

[0087] The outward surface 144 is formed at the outer tip of the engaging outward protrusion 141 in the left-right direction Y. The outward surface 144 is a surface extending along the XZ direction. The dimension of the outward surface 144 in the up-down direction Z is approximately equal to the dimension of the outer tip of the engaging outward protrusion 141 in the up-down direction Z. The outward surface 144 extends with the up-down direction Z as its longitudinal direction. The dimension of the outward surface 144 in the front-rear direction X is approximately equal over the entire length in the up-down direction Z.

[0088] The lumbar support support end 110 has an engaging inward convex portion 111, a rearward restricting surface 112, a forward abutment surface 113, an inward surface 114, a forward surface 115, an engaging protrusion portion 116, an engaging displacement portion 117, a groove 117A, an insertion recess 118, and a rear surface 119.

[0089] The lumbar support support end 110 is plate-shaped extending in the left-right direction Y. The cross-sectional outline of the lumbar support support end 110 along the XY direction is substantially rectangular. The longitudinal direction of the lumbar support support end 110 is the up-down direction Z. The thickness dimension of the lumbar support support end 110 in the front-back direction X is smaller than its height dimension in the up-down direction Z. The thickness dimension of the lumbar support support end 110 in the front-back direction X is set to be substantially uniform in the left-right direction Y, except for the outer tip in the left-right direction Y.

[0090] The height dimension of lumbar support end 110 in the up-down direction Z is set to be approximately uniform in the left-right direction Y. An insertion recess 118 having an opening 118a at the outer tip in the left-right direction Y is formed inside lumbar support end 110. Insertion recess 118 is formed extending in the left-right direction Y. The insertion recess 118 forms the interior of lumbar support end 110 into a hollow shape.

[0091] The engaging inward protrusion 111 is disposed at the outer end of the lumbar support end 110 in the left-right direction Y. The engaging inward protrusion 111 protrudes in the forward direction XF from the outer end of the lumbar support end 52 in the left-right direction. The base end 111g of the engaging inward protrusion 111 is connected to the outer end of the lumbar support end 52 in the left-right direction. The base end 111g is formed over the entire length of the lumbar support end 52 in the up-down direction Z. The base end 111g protrudes and extends in the forward direction XF. The end of the base end 111g in the forward direction XF is formed with an engaging inward protrusion 111a and an engaging inward protrusion 111b extending inward in the left-right direction Y. The inner surface of the base end 111g in the left-right direction Y is defined as an inward surface 114.

[0092] The engaging inward protrusion 111a and the engaging inward protrusion 111b are disposed apart in the up-down direction Z. The engaging inward protrusion 111a and the engaging inward protrusion 111b are formed at both ends of the base end 111g in the up-down direction Z, respectively. The engaging inward protrusion 111a and the engaging inward protrusion 111b have substantially the same contour shape when viewed from the front. The engaging inward protrusion 111a and the engaging inward protrusion 111b have substantially the same rectangular contour when viewed from the front. The base end 111g and the engaging inward protrusion 111a are formed in an L-shape in plan view. The base end 111g and the engaging inward protrusion 111b are formed in an L-shape in plan view. In the left-right direction Y, the length dimension of the engaging inward protrusion 111a is equal to the length dimension of the engaging inward protrusion 111b. In the up-down direction Z, the height dimension of the engaging inward protrusion 111a is equal to the height dimension of the engaging inward protrusion 111b in the up-down direction Z.

[0093] The engaging inward protrusion 111a has a height dimension in the up-down direction Z that is set to be approximately uniform over the entire length in the left-right direction Y. The engaging inward protrusion 111a has a thickness dimension in the front-rear direction X that is smaller than its height dimension in the up-down direction Z. The engaging inward protrusion 111a has a thickness dimension in the front-rear direction X that is set to be approximately uniform over the entire length in the left-right direction Y.

[0094] The engaging inward protrusion 111a has a forward surface 115 formed in the forward direction XF. The forward surface 115 is a surface extending along the YZ direction. The height dimension of the forward surface 115 in the up-down direction Z is equal to the height dimension of the engaging inward protrusion 111a. The forward surface 115 is formed over the entire length of the engaging inward protrusion 111a in the left-right direction Y. The forward surface 115 of the engaging inward protrusion 111a is flush with the forward surface 115 of the engaging inward protrusion 111b described later.

[0095] The engaging inward protrusion 111a has a rearward restriction surface 112 formed in the rear direction XB. The rearward restriction surface 112 is a surface extending along the YZ direction. The height dimension of the rearward restriction surface 112 in the up-down direction Z is equal to the height dimension of the engaging inward protrusion 111a. The rearward restriction surface 112 is formed over the entire length of the engaging inward protrusion 111a in the left-right direction Y. The rearward restriction surface 112 of the engaging inward protrusion 111a is flush with the rearward restriction surface 112 of the engaging inward protrusion 111b described later. In the engaging inward protrusion 111a, the rearward restriction surface 112 and the frontward surface 115 are substantially parallel to each other. The rearward restriction surface 112 is located rearward of the frontward surface 115 in the front-rear direction X.

[0096] The engaging inward protrusion 111a has an inward surface 114 formed at its inner tip in the left-right direction Y. The inward surface 114 is a surface extending along the YX direction. The height dimension of the inward surface 114 in the up-down direction Z is equal to the height dimension of the engaging inward protrusion 111a. The width dimension of the inward surface 114 in the front-rear direction X is equal to the thickness dimension of the engaging inward protrusion 111a. Although the inward surface 114 is formed as a flat surface, it is also possible for the boundary portion between the inward surface 114 and the forward surface 115 to be a curved surface with rounded corners, and for the boundary portion between the inward surface 114 and the rearward restricting surface 112 to be a curved surface with rounded corners.

[0097] The engaging inward protrusion 111b has a height dimension in the up-down direction Z that is set to be approximately uniform over the entire length in the left-right direction Y. The engaging inward protrusion 111b has a thickness dimension in the front-rear direction X that is smaller than its height dimension in the up-down direction Z. The engaging inward protrusion 111b has a thickness dimension in the rear direction X that is set to be approximately uniform over the entire length in the left-right direction Y.

[0098] The engaging inward protrusion 111b has a forward surface 115 formed in the forward direction XF. The forward surface 115 is a surface extending along the YZ direction. The height dimension of the forward surface 115 in the up-down direction Z is equal to the height dimension of the engaging inward protrusion 111b. The forward surface 115 is formed over the entire length of the engaging inward protrusion 111b in the left-right direction Y. The forward surface 115 of the engaging inward protrusion 111b is flush with the forward surface 115 of the engaging inward protrusion 111a.

[0099] The engaging inward protrusion 111b has a rearward restriction surface 112 formed in the rear direction XB. The rearward restriction surface 112 is a surface extending along the YZ direction. The height dimension of the rearward restriction surface 112 in the up-down direction Z is equal to the height dimension of the engaging inward protrusion 111b. The rearward restriction surface 112 is formed over the entire length of the engaging inward protrusion 111b in the left-right direction Y. In the engaging inward convex portion 111b, the rearward restricting surface 112 and the frontward surface 115 are substantially parallel to each other. The rearward restricting surface 112 is located rearward of the frontward surface 115 in the front-rear direction X.

[0100] The engaging inward protrusion 111b has an inward surface 114 formed at its inner tip in the left-right direction Y. The inward surface 114 is a surface extending along the YX direction. The height dimension of the inward surface 114 in the up-down direction Z is equal to the height dimension of the engaging inward protrusion 111b. The width dimension of the inward surface 114 in the front-rear direction X is equal to the thickness dimension of the engaging inward protrusion 111b. Although the inward surface 114 is formed as a flat surface, it is also possible for the boundary portion between the inward surface 114 and the forward surface 115 to be a curved surface with rounded corners, and for the boundary portion between the inward surface 114 and the rearward restricting surface 112 to be a curved surface with rounded corners.

[0101] The lumbar support end portion 110 includes a forward abutment surface 113 that faces the rearward restriction surface 112. The forward abutment surface 113 is a surface that extends along the YZ direction. The forward abutment surface 113 is approximately parallel to the rearward restriction surface 112. The forward abutment surface 113 is located rearward of the rearward restriction surface 112 in the front-rear direction X. The forward abutment surface 113 is spaced apart from the rearward restriction surface 112 in the front-rear direction X. The height dimension of the front-facing abutment surface 113 in the up-down direction Z is equal to the height dimension of the lumbar support end portion 110. The front-facing abutment surface 113 is formed longer than the overall length in the left-right direction Y at the engaging inward convex portion 111a and the engaging inward convex portion 111b. The front-facing abutment surface 113 is formed longer on the inside in the left-right direction Y than the front surface 115 in a front view. The front-facing abutment surface 113 has an area on the inside in the left-right direction Y that is not covered by the engaging inward convex portion 111a and the engaging inward convex portion 111b in a front view. The front-facing abutment surface 113 is able to come into contact with the rear-facing abutment surface 143.

[0102] The forward contact surface 113 has an engagement protrusion 116 formed at the center in the up-down direction Z. The engagement protrusion 116 protrudes from the forward contact surface 113 in the forward direction XF. In the engagement protrusion 116, the protrusion dimension from the forward contact surface 113 in the forward direction XF is smaller than the separation distance between the forward contact surface 113 and the rearward restriction surface 112 in the front-rear direction X. In the engagement protrusion 116, the protrusion dimension from the forward contact surface 113 in the forward direction XF is equal to or slightly smaller than the depth dimension of the recess 146 in the front-rear direction X relative to the rearward contact surface 143. In the engagement protrusion 116, the protrusion dimension from the forward contact surface 113 in the forward direction XF is larger than the front-rear rear X separation distance between the rear surface 119 and the front surface 20ga in the lumbar support device 100 assembled as described later. The front end surface of the engagement protrusion 116 abuts against the bottom surface of the recess 146.

[0103] The contour shape of the engagement protrusion 116 when viewed from the front is substantially the same as the contour shape of the recess 146 when viewed from the front. The engagement protrusion 116 has a protruding shape that is movable in the vertical direction Z from the recess 146. The engagement protrusion 116 is formed so that an end portion in the vertical direction Z is smoothly recessed from the front-facing abutment surface 113. The engagement protrusion 116 has an end portion in the vertical direction Z that is formed from a curved surface that is inclined in the vertical direction Z. The engaging protrusion 116 is disposed between the engaging inward protrusion 111a and the engaging inward protrusion 111b in the vertical direction Z. The engaging protrusion 116 is disposed below the engaging inward protrusion 111a in a front view. The engaging protrusion 116 is disposed above the engaging inward protrusion 111b in a front view. The engaging protrusion 116 is spaced apart in the vertical direction Z from the engaging inward protrusion 111a and the engaging inward protrusion 111b in a front view.

[0104] An engagement displacement portion 117 is formed around the engagement protrusion 116. The engagement displacement portion 117 is formed as a region separated from the outer forward abutment surface 113 in a front view by a groove 117A formed around the engagement protrusion 116. The groove 117A penetrates from the front-facing contact surface 113 to the insertion recess 118. The groove 117A is formed in a substantially U-shape when viewed from the front. The groove 117A is not formed on the inside in the left-right direction Y. The portion where the groove 117A is not formed becomes a base portion 117b of the engagement displacement portion 117.

[0105] The engaging displacement portion 117 has a base portion 117b on the inside in the left-right direction Y. The engaging displacement portion 117 is connected to the periphery by the base portion 117b. The engaging displacement portion 117 has an engaging protrusion portion 116 disposed on the outside of the tip end in the left-right direction Y. The base 117b does not displace in the front-rear direction X relative to the lumbar support end 110. The outer side of the engagement displacement portion 117 in the left-right direction Y is displaceable in the front-rear direction X. As the engagement displacement portion 117 displaces in the front-rear direction X, the engagement protrusion portion 116 is displaceable in the front-rear direction X.

[0106] The insertion recess 118 is open to the outside of the lumbar support end portion 110 in the left-right direction Y. The diameter dimension of the insertion recess 118 in the up-down direction Z is uniform over the entire length in the left-right direction Y. The gripping member 170 is inserted into the insertion recess 118 from the opening 118a toward the inside in the left-right direction Y. The insertion recess 118 is also open on both sides in the up-down direction Z of the lumbar support supporting end portion 110 .

[0107] The insertion recess 118 has an opening 118a at a portion spaced inward from the outer end of the lumbar support end 110 in the left-right direction Y. The opening 118a is in contact with the engaging inward protrusions 111a and 111b at its outer position in the left-right direction Y. The opening 118a also serves as a locking portion 118c that locks a gripping member 170 (described later) inserted into the insertion recess 118 inside the insertion recess 118.

[0108] Fig. 11 is a perspective view showing a grip member in this embodiment. Fig. 12 is a perspective view showing a guide member in this embodiment. Fig. 13 is a perspective view showing a guide member in this embodiment. Fig. 14 is a vertical cross-sectional view showing an engagement protrusion and a recess in this embodiment. The gripping member 170 has locking portions 174 corresponding to the locking portions 118c on both sides in the up-down direction Z. The locking portions 118c and the locking portions 174 have, for example, a snap-fit ​​structure. By locking the locking portions 118c and the locking portions 174, the gripping member 170 is fixed in a state in which it does not come out of the insertion recess 118.

[0109] The gripping member 170 is fixed in a state in which it protrudes outward from the opening 118a in the left-right direction Y. The gripping member 170 penetrates through the through-hole 22 of the right support frame 20d on the outside in the left-right direction Y from the opening 118a. The through hole 22 penetrates the right support frame 20d in the left-right direction Y. The through hole 22 penetrates the left support frame 20c in the left-right direction Y. The inside of the through hole 22 in the left-right direction Y opens into the mounting recess 20g. The opening of the through hole 22 faces the opening 118a. The opening of the through hole 22 is located outside the opening 118a in the left-right direction Y. The diameter of the through hole 22 is larger than that of the opening 118a.

[0110] An allowance recess 177 that allows rearward displacement of the engaging displacement portion 117 is formed on the front surface of the gripping member 170. The gripping member 170 contacts the rear of the engaging displacement portion 117 inside the insertion recess 118. In a front view, the allowable recess 177 has a contour shape that is the same as or slightly smaller than the contour of the engaging displacement portion 117. The depth dimension of the allowable recess 177 in the front-rear direction X is set to be shallower on the inside than on the outside in the left-right direction Y. This corresponds to the fact that the allowable displacement of the engaging displacement portion 117 in the front-rear direction X is larger near the engaging protrusion 116 than in the base 117b.

[0111] The gripping member 170 penetrates the guide member 160 inside the through hole 22. The guide member 160 protrudes outward in the left-right direction Y beyond the right support frame 20d. A flange portion 161f (described later) of the guide member 160 protrudes outward in the left-right direction Y beyond the left support frame 20c. The gripping member 170 penetrates the through hole 22 formed in the back frame portion 20 of the backrest 5 in the left-right direction Y and protrudes outward.

[0112] A cylindrical guide member 160 is disposed in the through hole 22. A gripping member 170 passes through the guide member 160. The guide member 160 includes an inner cylindrical member 161 and an outer cylindrical member 165 .

[0113] The outer tube member 165 is housed inside the through hole 22. The outer tube member 165 has a slit 165s which is a through hole coaxial with the through hole 22. The inner tube member 161 is arranged coaxially inside the slit 165s. The outer tube member 165 has locking portions 165c on both sides in the up-down direction Z. The locking portions 165c are located at the inner end of the outer tube member 165 in the left-right direction Y. The locking portions 165c are locked to the upper and lower ends 22c of the through hole 22. The locking portions 165c lock the outer tube member 165 to the through hole 22. The outer tube member 165 has a flange portion 165f with an expanded diameter on the outer side in the left-right direction Y. The flange portion 165f abuts against a step 22f formed at the outer opening of the through hole 22 in the left-right direction Y. The flange portion 165f and the step 22f abut against each other, thereby locking the outer tube member 165 in the through hole 22.

[0114] The inner tube member 161 is housed inside the slit 165s of the outer tube member 165. The inner tube member 161 has a flange portion 161f that protrudes outward in the left-right direction Y from the through hole 22 and the outer tube member 165. The inner tube member 161 has a slit 161s that is a through hole coaxial with the through hole 22. The inner tube member 161 has locking portions 161c on both sides in the up-down direction Z. The locking portions 161c are located at the inner end of the inner tube member 161 in the left-right direction Y. The locking portions 161c are locked to the upper and lower ends 165cc of the outer tube member 165. The inner tube member 161 has locking portions 161e slightly inward in the up-down direction Z from the locking portions 161c. The locking portions 161e are locked to locking recesses 165e formed in the side wall portions on both sides in the front-rear direction X of the outer tube member 165. Both the locking portion 161c and the locking portion 161e are locked to the upper and lower ends 165cc and the locking recesses 165e, so that the inner tube member 161 is locked around the slits 165s of the outer tube member 165 in both the up-down direction Z and the front-rear direction X. As a result, the inner tube member 161 is locked to the back frame portion 20 via the outer tube member 165.

[0115] A gripping member 170 is disposed penetrating the inside of the slit 161s. The vertical dimension Z of slit 161s is larger than the vertical dimension Z of gripping member 170. Grip member 170 is movable in the vertical direction Z inside slit 161s. The front-rear dimension X of slit 161s is slightly larger than the front-rear dimension X of gripping member 170.

[0116] In this embodiment, the lumbar support device 100 has a lumbar support support end 110 supported by a mounting member 140. The lumbar support support end 110 is supported by the mounting members 140 at both ends of the lumbar support 50. The rearward abutment surface 143 and the forward abutment surface 113 constitute a vertical relative position regulating means. The vertical relative position regulating means is capable of regulating the relative position in the vertical direction Z between the mounting member 140 and the lumbar support support end 110. The vertical relative position regulating means supports the lumbar support support end 110 so that it can move up and down relative to the mounting member 140 by the rearward abutment surface 143 and the forward abutment surface 113 coming into contact with each other. The vertical relative position regulating means maintains a state in which the forward abutment surface 113 contacts the rearward abutment surface 143 from behind, even if the lumbar support support end 110 moves up and down relative to the mounting member 140.

[0117] The rearward restricting surface 112 and the forward restricting surface 142 constitute a front-rear position restricting means. The front-rear position restricting means is capable of restricting the positions of the mounting member 140 and the lumbar support supporting end 110 in the front-rear direction X. The front-rear position restricting means restricts the positions in the front-rear direction X by the rearward restricting surface 112 and the forward restricting surface 142 coming into contact with each other. The front-rear position restricting means maintains a state in which the forward restricting surface 142 contacts the rearward restricting surface 112 from behind, even if the lumbar support supporting end 110 moves up and down relative to the mounting member 140.

[0118] The inward surface 114 and the outward surface 144 constitute a left-right direction position regulating means. The left-right direction position regulating means can regulate the positions of the mounting member 140 and the lumbar support support end 110 in the left-right direction Y. The left-right direction position regulating means regulates the positions of the mounting member 140 and the lumbar support support end 110 in the left-right direction Y by the inward surface 114 and the outward surface 144 coming into contact with each other. The left-right direction position regulating means maintains a state in which the inward surface 114 contacts the outward surface 144 from the outside in the left-right direction Y, even if the lumbar support support end 110 moves up and down relative to the mounting member 140.

[0119] Here, the front restriction surface 142 is located rearward of the rear restriction surface 112 , the rear abutment surface 143 is located rearward of the front restriction surface 142 , and the front abutment surface 113 is located rearward of the rear abutment surface 143 . As a result, the engaging outward convex portion 141 and the engaging inward convex portion 111 can move relative to each other in the up-down direction Z while meshing with each other in the left-right direction Y. The lumbar support device 100 maintains a state in which the engaging inward convex portion 111 is engaged with the groove portion 148 from the outside in the left-right direction Y in a plan view.

[0120] The engaging displacement portion 117, the engaging protrusion 116, and the recess 146 constitute a vertical relative position regulating means. The engaging protrusion 116 fits into one of the recesses 146, so that the lumbar support support end 110 can be supported without moving in the vertical direction Z relative to the mounting member 140. This allows the lumbar support 50 to be supported without moving in the vertical direction Z relative to the back frame portion 20. In the normal use state of the chair 1, the engaging protrusion 116 fits into one of the recesses 146 and does not come off this recess 146. Therefore, the lumbar support 50 does not move in the vertical direction Z relative to the back frame portion 20.

[0121] In this embodiment, the vertical relative position regulating means, the front-rear position regulating means, and the left-right position regulating means can all be composed of the mounting member 140 and the lumbar support supporting end 110. This makes it possible to easily regulate the position or move in these three directions without increasing the number of parts. Specifically, the rearward abutment surface 143 maintains contact with the frontward abutment surface 113. The rearward restriction surface 112 maintains contact with the frontward restriction surface 142. The inward surface 114 maintains contact with the outward surface 144.

[0122] In addition, when a load is applied from the seated person to the lumbar support main body 51 in the rear direction XB, the rearward abutment surface 143 and the frontward abutment surface 113 maintain a state of contact. The dimension in the front-rear direction X where the engagement protrusion 116 is fitted into the recess 146 is larger than the separation distance in the front-rear direction X between the rear surface 119 and the front surface 20ga. Therefore, even if the lumbar support support end portion 110 is displaced toward the rear direction XB, the engagement protrusion 116 remains fitted into the recess 146 when the rear surface 119 is in contact with the front surface 20ga. In other words, even if a load is applied from the seated person to the lumbar support main body 51 in the rear direction XB, the engagement protrusion 116 maintains a state of being fitted into the recess 146.

[0123] At the same time, even when the rearward restricting surface 112 and the frontward restricting surface 142 are spaced apart from each other, the distance between the rearward restricting surface 112 and the frontward restricting surface 142 in the front-rear direction X is smaller than the dimension in the front-rear direction X where the engaging protrusion 116 is fitted into the recess 146. Therefore, even when the lumbar support support end 110 is displaced toward the rearward direction XB, the engaging protrusion 116 is fitted into the recess 146 when the rearward restricting surface 112 is in contact with the frontward restricting surface 142. In other words, even when a load is applied to the lumbar support main body 51 from the seated person toward the rearward direction XB, the engaging protrusion 116 maintains the state of being fitted into the recess 146.

[0124] Furthermore, since the engaging inward convex portion 111a and the engaging inward convex portion 111b are engaged inward in the left-right direction Y with respect to the groove portion 148 that opens outward in the left-right direction Y, even if a load is applied to the lumbar support main body 51 in the rear direction XB, the engaging inward convex portion 111a and the engaging inward convex portion 111b are only pulled inward in the left-right direction Y and will not come off the groove portion 148. This prevents the lumbar support supporting end portion 110 from coming off the mounting member 140. Therefore, the engaging protrusion portion 116 is maintained in a state of being fitted into the recess portion 146.

[0125] By maintaining the state in which the engaging protrusion 116 is fitted into the recess 146, the lumbar support end 110 does not move up and down relative to the mounting member 140. This prevents the lumbar support 50 from moving up and down relative to the back frame portion 20, and allows the support to be maintained at the desired position.

[0126] Next, a procedure for moving the lumbar support 50 in the vertical direction Z relative to the back frame portion 20 will be described.

[0127] The outer end of the grip member 170, which protrudes outward in the left-right direction Y from the back frame portion 20, is operated, for example, by being pinched by the fingers of a seated person. Note that the operation here means moving the grip member 170 in the up-down direction Z. At this time, the grip member 170 moves in the up-down direction Z inside the slit 161s along the slit 161s.

[0128] Then, as the outer end of the gripping member 170 moves in the vertical direction Z, a force moving in the vertical direction Z is applied to the lumbar support supporting end 110 via the inner surface of the insertion recess 118 in which the gripping member 170 fits.

[0129] When a force is applied to the lumbar support support end 110 to move in the up-down direction Z, the lumbar support support end 110 moves in the up-down direction Z by the up-down relative position regulating means while maintaining its posture, with its position in the left-right direction Y and the front-to-back direction X relative to the mounting member 140 regulated by the front-to-back position regulating means and the left-to-right position regulating means. Specifically, the rearward abutment surface 143 and the frontward abutment surface 113 maintain their contact state. The rearward restriction surface 112 and the frontward restriction surface 142 maintain their contact state. The inward surface 114 and the outward surface 144 maintain their contact state. At this time, the front end surface of the engagement protrusion 116 contacts the bottom surface of the recess 146.

[0130] When the lumbar support end portion 110 starts to move in the vertical direction Z relative to the mounting member 140, the engaging protrusion portion 116 and the recessed portion 146 that are engaged with each other move in the vertical direction Z relative to each other. The engaging protrusion 116 and the recess 146 come into contact with each other in response to the dimensional change in the front-to-rear direction X formed by the inclination of each of them in the up-down direction Z, and the engaging protrusion 116 and the recess 146 are further pressed against each other in the front-to-rear direction X.

[0131] Here, the engaging outward convex portion 141 in which the recess 146 is formed does not displace. In contrast, the engaging displacement portion 117 in which the engaging protrusion 116 is located can be elastically deformed with the base portion 117b as a fulcrum. Therefore, when the engaging protrusion 116 is pressed in the rear direction XB by the recess 146, the engaging displacement portion 117 is displaced in the rear direction XB with the base portion 117b as a fulcrum.

[0132] Furthermore, when the lumbar support end portion 110 moves in the up-down direction Z relative to the mounting member 140, the engaging protrusion 116 is displaced in the rear direction XB so as to come out of the recess 146. When the engaging protrusion 116 comes out of the recess 146 in a front view, the engaging protrusion 116 comes into contact with the rearward abutment surface 143. At this time, the engaging displacement portion 117 is located inside the allowable recess 177 and does not abut against the grip member 170. Due to the allowable recess 177, the engaging displacement portion 117 does not interfere with the grip member 170, and the engaging protrusion 116 is displaced in the rear direction XB. At this time, the rearward contact surface 143 and the frontward contact surface 113 maintain a state of contact.

[0133] When the engaging protrusion 116 is disengaged from the recess 146 , the lumbar support supporting end portion 110 becomes easily movable in the up-down direction Z relative to the mounting member 140 . Furthermore, when the lumbar support supporting end 110 moves in the up-down direction Z relative to the mounting member 140, the engaging protrusion 116 fits into the next recess 146 adjacent to the recess 146 that was previously disengaged. Then, the engaging displacement portion 117 is displaced in the forward direction XF from the allowable recess 177 by the elastic restoring force and returns to its original state. At this time, the engaging protrusion 116 fits into the next recess 146, and the lumbar support supporting end 110 is supported by the mounting member 140.

[0134] This allows the support height of the lumbar support support end portion 110 relative to the mounting member 140 to be changed. In addition, by selecting one of the recesses 146 at a predetermined position and engaging the engaging protrusion 116 with the recess 146, the support height of the lumbar support support end 110 with respect to the mounting member 140 can be set. At this time, even if the lumbar support 50 moves in the vertical direction Z, the posture viewed in the horizontal direction Y does not change. In addition, since the opening direction of the recess 146 is rearward, when a load is input to the lumbar support main body 51 via the back or waist of the seated person, the contact between the front end surface of the engaging protrusion 116 and the bottom surface of the recess 146 may be released. In this case, the engaging protrusion 116 can be removed from the recess 146 in the vertical direction with a light force.

[0135] In this embodiment, when a user applies force by gripping the grip member 170 with his / her fingers to move the lumbar support 50 in the vertical direction, the applied force is transmitted from the inside of the insertion recess 118 of the lumbar support device 100, which is movable in the vertical direction within the guide member 160, to the lumbar support support end 110 via the grip member 170. Therefore, the lumbar support main body 51 is prevented from bending due to the force applied to move the lumbar support 50 in the vertical direction. As a result, the operability when sliding the lumbar support 50 in the vertical direction can be improved.

[0136] In this embodiment, by selecting one of the recesses 146 at a predetermined position and engaging the engagement protrusion 116, the vertical position of the lumbar support 50 can be determined when the lumbar support 50 is moved in the vertical direction. The engagement displacement portion 117 is elastically deformable in the front-rear direction X. Therefore, when the lumbar support 50 is moved in the vertical direction, when the engagement protrusion 116 is disengaged from the recess 146, the engagement displacement portion 117 is elastically deformed, and the lumbar support 50 can easily move in the vertical direction. In addition, when the engagement protrusion 116 enters the recesses 146 located above and below, the elastically deformed engagement displacement portion 117 is restored to its original shape. As a result, the state in which the engagement protrusion 116 enters the recess 146 is maintained, and the restraining force of the vertical movement of the lumbar support 50 is increased.

[0137] In this embodiment, the chair 1 is equipped with the lumbar support device 100 described above. According to this configuration, the operational feel when sliding the lumbar support 50 in the up and down direction can be improved.

[0138] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the attached claims.

[0139] Furthermore, in the lumbar support device 100, as shown in FIG. 15, a second engagement protrusion 116b protruding in the rear direction XB from the rear surface 119 of the lumbar support end portion 110 can be provided, and a second recess 26b opening in the forward direction XF can be formed in the rear surface 20ga of the mounting recess 20g, so that the second engagement protrusion 116b and the second recess 26b can be configured to engage with each other. In this case, the second engagement protrusion 116b and the second recess 26b maintain a state in which the right-facing surface 116b2 of the second engagement protrusion 116b and the left-facing surface 26b2 of the second recess 26b are in contact with each other, and the left-facing surface 116b1 of the second engagement protrusion 116b and the right-facing surface 26b1 of the second recess 26b are in contact with each other. This allows the lumbar support end 110 to be supported movably in the up-down direction Z while maintaining its positional restriction in the left-right direction Y relative to the back frame portion 20 and the mounting member 140.

[0140] In addition, the second engagement protrusion 116b and the second recess 26b maintain a state in which the rearward surface 116b3 of the second engagement protrusion 116b and the rearward surface 26b3 of the second recess 26b are in contact with each other. This allows the lumbar support end 110 to be supported movably in the up-down direction Z while maintaining positional restrictions in the front-back direction X and the left-right direction Y relative to the back frame portion 20 and the mounting member 140.

[0141] With this configuration, the support height of the lumbar support support end 110 relative to the mounting member 140 can be set in the same way. At this time, even if the lumbar support 50 moves in the up-down direction Z, the posture viewed in the left-right direction Y does not change. In addition, since the protruding direction of the second engagement protrusion 116b is rearward, when a load is input to the lumbar support main body 51 through the back or waist of the seated person, the contact between the rearward surface 166b3 of the second engagement protrusion 116b and the forward surface 26b3 of the second recess 26b is not released, but rather they are pressed against each other, so in this case, the second engagement protrusion 116b does not come out of the second recess 26b. In addition, in this case, it is also possible to omit the engagement inward protrusion 111 and the groove portion 148, that is, to provide a left-right direction position regulating means and a front-rear direction position regulating means between the back frame portion 20 and the lumbar support main body 51.

[0142] In the present invention, it is also possible to individually select the individual configurations in the above-described embodiments and combine them to implement the present invention. In addition, the components in the above-described embodiments can be replaced with well-known components or can be combined as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0143] 1. Chair 20…Back frame 20b…Lower support frame 20b1…Rear wall part 20c…Left support frame (support frame) 20d…Right support frame (support frame) 20f…Front 20g…Mounting recess 20ga...Front 20w...outer wall part 22...Through hole 50…Lumbar support 51…Lumbar support body 52…Lumbar support end 100...Lumbar support device 110...Lumbar support end 111,111a,111b...Engagement inward convex part 111g…Proximal end 112…Backwards restriction surface 113...Anterior contact surface 114…introverted side 115…Anterior surface 116...Engagement protrusion 117... Engagement displacement portion 117A…groove 117b…Base 118…Insertion recess 118a...Opening 118c…Locking part 119...Rear side 140...Mounting member 140a…Front 141...Engagement outward protrusion 142...Forward regulatory surface 143…Rearward contact surface 144...Extroverted side 145...Posterior face 145A…Front mounting 146…Recess 148…Groove 148a…Mounting foot 148b…Mounting foot 160...Guide member 161...Inner cylinder member 161c…Locking part 161s…Slit 165...Outer cylinder member 165c…Locking part 165s…Slit 170...Grip member 174…Latching part 177...Allowable recess

Claims

1. A pair of left and right mounting members; A lumbar support body extending in the left-right direction between the pair of left and right mounting members; Lumbar support support ends supported by the pair of left and right mounting members at both left and right end positions of the lumbar support body; A lumbar support device comprising: The mounting member includes a rearward abutment surface that covers a front portion of the lumbar support end portion and extends in a vertical direction, The lumbar support support end portion includes a front contact surface that contacts the rear contact surface from behind, The rearward contact surface and the forward contact surface constitute a vertical relative position regulating means that can regulate the relative position in the vertical direction between the mounting member and the lumbar support end, and the vertical relative position regulating means supports the lumbar support end on the mounting member so that it can move up and down by contacting the rearward contact surface and the forward contact surface with each other. A lumbar support device characterized by:

2. The lumbar support end portion includes a rearward restricting surface facing the forward contact surface, The mounting member includes a forward restriction surface facing the rearward restriction surface, the rearward restriction surface and the forward restriction surface constitute a front-rear direction position restriction means that can restrict the positions of the mounting member and the lumbar support end portion in the front-rear direction, The front-rear direction position restriction means restricts the position in the front-rear direction by contacting the rearward restriction surface and the forward restriction surface with each other.

2. The lumbar support device according to claim 1.

3. the forward restriction surface is located rearward of the rearward restriction surface, the rearward abutment surface is located rearward of the forward restriction surface, and the forward abutment surface is located rearward of the rearward abutment surface, 3. The lumbar support device according to claim 2.

4. The lumbar support end portion has an inward surface that connects the forward contact surface and the rearward restriction surface on the outer side in the left-right direction, The mounting member has an outward surface facing the inward surface, the inward surface and the outward surface constitute a left-right direction position restricting means for restricting the left-right direction positions of the mounting member and the lumbar support end portion, The left-right direction position restriction means restricts the left-right direction positions of the mounting member and the lumbar support end portion by contacting the inward surface and the outward surface with each other.

4. The lumbar support device according to claim 3.

5. the mounting member is provided with an engaging outward protrusion having the forward restricting surface, the rearward abutting surface, and the outward surface, The lumbar support support end portion is provided with an engaging inward protrusion having the rearward restricting surface and the inward surface forward of the forward contact surface, the engaging outward convex portion and the engaging inward convex portion are movable relative to each other in the up-down direction while being engaged with each other in the left-right direction, 5. The lumbar support device according to claim 4.

6. The vertical relative position regulation means is an engagement protrusion formed on the front contact surface and protruding forward; a recess formed on the rear contact surface, the recess opening rearward and engaging with the engaging protrusion; having A plurality of the recesses are arranged in the vertical direction.

6. The lumbar support device according to claim 5.

7. The engaging inward convex portion is divided into upper and lower portions spaced apart from each other, and the engaging protrusion portion is disposed between the engaging inward convex portions in the vertical direction.

7. The lumbar support device according to claim 6.

8. A groove is formed around the engagement protrusion to form an engagement displacement portion that allows the engagement protrusion to be displaced in the front-rear direction, and the engagement displacement portion has a base portion on the inner side in the left-right direction that does not displace in the front-rear direction.

8. The lumbar support device according to claim 7.

9. The lumbar support end portion has an insertion recess extending from the outside to the inside in the left-right direction, the insertion recess being formed at a rear position of the engagement displacement portion, The gripping member is inserted into the insertion recess in a state where it protrudes outward in the left-right direction from the insertion recess.

9. The lumbar support device according to claim 8.

10. An allowance recess for allowing the engagement displacement portion to be displaced rearward is formed on the front surface of the gripping member.

10. The lumbar support device according to claim 9.

11. A locking portion is formed inside the gripping member and the insertion recess to lock the gripping member to the lumbar support end portion.

11. The lumbar support device according to claim 10.

12. A lumbar support device according to any one of claims 1 to 10, The mounting member is attached to the backrest. A chair characterized by:

13. The lumbar support device according to claim 11, The mounting member is attached to the backrest, The gripping member protrudes outward through a through hole formed in the backrest in the left-right direction. A chair characterized by:

14. A cylindrical guide member is disposed in the through hole, and the gripping member passes through the guide member.

14. The chair according to claim 13.

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