JP7390096B2 - Backrest locking range adjustment mechanism and chair - Google Patents

Description

The present invention relates to a backrest locking range adjustment mechanism and a chair. More specifically, the present invention relates to a locking range adjustment mechanism and a chair that allow the locking range of the backrest of the chair to be adjusted.

2. Description of the Related Art Conventionally, there have been chairs equipped with a locking range adjustment mechanism that allows the locking range of the backrest to be adjusted. For example, in a chair in which the seat and backrest are synchronized and locked between a standing posture and a backward leaning posture, the seat is directly attached to the shaft that supports the support (main frame) on the legs so that it can slide back and forth. a regulating member that acts on the regulator to changeably regulate the sliding range of the shaft; an operating member that operates the regulating member; a transmission shaft that transmits the operating force of the operating member to the regulating member; There is one that is provided with a click stop mechanism that is fixed at a retracted position that does not restrict the sliding range of the shaft and a plurality of restriction positions that restrict the sliding range of the shaft (Patent Document 1).

Japanese Patent Application Publication No. 2004-33444

However, the locking range adjustment mechanism described in Patent Document 1 requires a large-scale mechanism in the mechanical part, resulting in an increase in the size of the mechanism. In this case, the mechanical part under the seat becomes large, making it difficult to obtain a simple and clean appearance. Furthermore, the structure is based on synchronized locking, in which the backrest locks in synchronization with the seat, and is a mechanism that cannot be used with a simple backrest locking or weight sensing mechanism.

SUMMARY OF THE INVENTION An object of the present invention is to provide a backrest locking range adjustment mechanism and a chair that can downsize the mechanical part under the seat.

To achieve this purpose, the backrest locking range adjustment mechanism regulates the locking range of the backrest of a chair with a locking function that allows the backrest to tilt backwards, and the locking range adjustment mechanism regulates the locking range of the backrest of a chair that has a locking function that allows the backrest to tilt backward. A backrest reaction force mechanism that utilizes springs that generate force to push back the backrest between the main frame and apply it to members that interlock with the backrest, and is arranged concentrically with the spring of the backrest reaction mechanism. The locking range adjustment mechanism includes a movable member that moves in the axial direction of the spring in conjunction with the locking of the backrest by coming into contact with a member that moves in conjunction with the backrest, and a movable member that moves in the axial direction of the spring in conjunction with the locking of the backrest. The switching member is fixed to the main frame and is rotatable around the axis. The minimum distance between the end surfaces facing each other with the movable member is variable, and the minimum distance portions are abutted against each other to prevent the movement of the interlocking member and locking of the backrest, and the distance between the minimum distance portions is widened. This allows the backrest to lock.

Here, a convex part protruding in the axial direction is formed on one of the mutually opposing end surfaces of the switching member or the movable member, and a concave part into which the convex part enters is formed on the other, and the convex part By coming into contact with the end face, it prevents the movable member from moving in the axial direction and restricts the locking range of the backrest, while at the same time, the movable member can move in the axial direction at the position where the convex part enters the concave part, thereby locking the backrest. It is preferable that

In addition, while the movable member has a convex portion on the end surface, the switching member has a concave portion on the end surface, and the tip surface of the convex portion functions as a perpendicular end surface that abuts against the end surface of the switching member to prevent its movement. It is preferable to switch the position of either the concave portion or the perpendicular end face to the front of the convex portion of the movable member by rotating the movable member, thereby releasing the locking restriction or switching the locking restriction.

Further, the locking restriction position is not limited to a specific position, but is preferably an initial position.

Moreover, it is preferable that the locking range adjustment mechanism is disposed outside the spring and covers the spring.

Further, it is preferable that the switching member is provided with a rotational operation means that penetrates the main frame and protrudes to the outside on the outer circumferential surface or the front end surface of the switching member.

Furthermore, the movable member includes a spring mount receiver that supports the rear end of the spring of the backrest reaction force mechanism, a bearing part that swingably engages with a member that interlocks with the backrest, and a mount pin receiver part that holds the mount pin. It is preferable that the rear spring mount also be used as a rear spring mount.

Further, it is preferable that the chair incorporates the backrest locking range adjustment mechanism according to any one of claims 1 to 7.

According to the device according to claim 1, by configuring the locking range adjustment mechanism concentrically with the reaction force adjustment mechanism, the mechanical part under the seat can be downsized, improving space efficiency and providing a simple and clean appearance. is obtained.

1 is a perspective view from below showing an embodiment of a chair to which the present invention is applied. It is a perspective view seen from above showing a main frame and a back support rod of the same chair. 3 is a perspective view showing an embodiment of a spring-type backrest reaction force mechanism and a locking range adjustment mechanism housed in the main frame of FIG. 2. FIG. It is a perspective view of the same spring-type backrest reaction force mechanism and locking range adjustment mechanism. It is an exploded perspective view of the same spring-type backrest reaction force mechanism and locking range adjustment mechanism. FIG. 3 is a perspective view of the main frame seen from above. FIG. 3 is a longitudinal sectional view of the main frame, the backrest reaction force mechanism, and the locking range adjustment mechanism. It is a perspective view seen from the back side of the presser plate which presses down a switching member. It is a perspective view seen from below of a main frame, a spring-type backrest reaction force mechanism, and a locking range adjustment mechanism showing a second embodiment of the present invention. It is a perspective view seen from above of a main frame, a spring-type backrest reaction mechanism, and a locking range adjustment mechanism according to a second embodiment. It is a perspective view seen from above showing a main frame, a spring-type backrest reaction force mechanism, a locking range adjustment mechanism, and a back support rod, showing a third embodiment of the present invention. It is a perspective view seen from above showing a main frame, a back support rod, and a locking range adjustment mechanism concerning a third embodiment. It is a perspective view seen from above of the main frame concerning the same third embodiment. FIG. 7 is a perspective view of a spring-type backrest reaction force mechanism and a locking range adjustment mechanism according to the third embodiment. It is an exploded perspective view of the same spring-type backrest reaction force mechanism and locking range adjustment mechanism. It is an exploded perspective view of the same locking range adjustment mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described in detail below based on embodiments shown in the drawings. In this specification, the front, back, left, and right directions are defined with the seated person at the center, and the term "front" refers to the front of the chair and the seated person sitting on the seat of the chair, respectively. or forward-facing, and "rear or backwards" likewise means rearward or backward-facing for the chair and the seated person. Further, the direction orthogonal to the front-rear direction in the horizontal plane is the left-right direction for the seated person in each of the seat and backrest, and is the width direction of the chair. Further, "upper" and "lower" refer to the upper and lower sides of the seat and backrest, respectively, for the chair and the seated person, and the upper and lower sides in the vertical plane.

FIGS. 1 to 8 show an embodiment of a chair to which the present invention is applied. For example, as shown in FIG. 1, this chair includes legs 1 having casters, a main frame 2 supported by the legs 1, and a seat 3 that is swingably supported by the main frame 2 and interlocks with each other. and a backrest 4, and a mechanism that adjusts the lockable range of the backrest by regulating the locking range of the backrest 4 in at least one position, for example, the initial position or another position (referred to as a locking range adjustment mechanism 51). ). Adjusting the locking range means not only restricting it to multiple positions, but also restricting it to a single position, or the state where locking is not possible due to hitting the initial position (the position of the backrest when there is no seated person). Adjustment of the locking range also includes adjusting the locking range.

Here, the backrest 4 is not limited to a specific structure or shape; The back structure may be supported by a back support rod 5 that is swingably connected to the main frame 2. Similarly, the seat 3 is not limited to a specific structure or shape, but for example, the seat 3 may be a so-called so-called seat 3 in which the inner shell is completely covered with a cushioning material and a bag-like upholstery (not shown). As a whole seat structure, it is supported by a main frame 2 and a back support rod 5 so as to be swingable.

In the case of this embodiment, the back support rod 5 has a generally horizontal L-shape as shown in FIG. , the front part of the long side extending forward is swingably connected to the main frame 2 by the backrest rotation shaft 6, and the part on the front side of the backrest rotation shaft 6 (hereinafter referred to as arm part 32). The structure is such that the reaction force receiving shaft 7 at the tip of the backrest reaction force mechanism 50 receives and supports one spring mount, for example, the rear spring mount 43.

In the case of the present embodiment, the seat 3 is provided with a pair of brackets 13 and 14 on both the front and rear sides of the outer frame, for example, on the back side of the outer frame, and a connecting shaft passing through the long hole 12 on the front end side of the main frame 2. 9 and a rotating shaft 10 penetrating through a bracket 15 formed on the rear side of the backrest rotational shaft 6 of the backrest 5 are respectively attached, and in conjunction with the swinging of the backrest 5, the seat is rotated. 3 is supported so that it moves back and forth while the rear side rises and falls (moves up and down).

Here, in the case of the present embodiment, the main frame 2 has left and right side walls, for example, as shown in FIG. 27 and a bottom wall part 26, the cylindrical part 23 into which the gas spring of the leg 1 is fitted, and the bearing hole 24 through which the backrest rotating shaft 6 is inserted and pivotally connected. is provided. In this embodiment, the box shape is formed by welding, for example, a steel material, but the box shape is not particularly limited to this, and it may be integrally formed by aluminum die casting or the like.

A backrest reaction force mechanism 50 including a compression coil spring 41 is housed in the main frame 2, and includes a reaction force receiving shaft 7 at the tip of the arm portion 32 of the back support rod 5 and a support shaft 11 at the front end side of the main frame 2. The spring 41 is supported between the springs 41 and 41, and when the backrest 4 tilts backward, the rear spring mount 43 is pushed forward and the spring 41 is compressed, thereby generating a force/reaction force that tries to push back the backrest 4. It is set up like this.

In the case of this embodiment, the backrest reaction force mechanism 50 includes a reaction force spring, for example, one compression coil spring 41, front and rear spring mounts 42, 43 disposed at the front and rear ends thereof, and springs, as shown in FIG. The support shaft 11 in front of the main frame 2 and the reaction force at the tip of the arm part 32 in front of the back support rod 5 are received via spring mounts 42 and 43. It is installed between the shaft 7 and the shaft 7. Then, in conjunction with the backward tilt of the backrest 4, the spring 41 generates a force between the main frame 2 and the main frame 2 to push back the backrest 4, and the member that interlocks with the backrest 4 (in this embodiment It is attached to the back support rod 5).

In the case of this embodiment, the front spring mount (hereinafter referred to as the front spring mount 42) includes, for example, a disk-shaped spring mount receiver 46 that supports the spring 41 and the support shaft 11, as shown in FIG. It is composed of a bifurcated bearing part 47 to be able to swing against the spring 41, and a cylindrical mount pin receiving part 45 that is fitted inside the spring 41 and supports the mount pin 44. It is provided to receive and support the tip of the spring 41 and to fit and support the tip side of the mount pin 44 in the mount pin receiving portion 45 . The front spring mount 42 is swingably supported using a support shaft 11 fixed to the main frame 2.

On the other hand, in this embodiment, the rear spring mount (hereinafter referred to as the rear spring mount 43) is, for example, a cylindrical spring mount receiver (of the locking range adjustment mechanism 51) that accommodates and supports the other end of the spring 41. (also serves as a movable member 34), a bifurcated bearing part 47 for being able to swing relative to the reaction force receiving shaft 7, and a cylindrical mount pin receiving part 45 that supports the mount pin 44. There is. The spring mount receiver, which also serves as the movable member 34, and the mount pin receiver 45 are in a double cylinder state, and the mount pin 44 is accommodated in the hole 48 of the mount pin receiver 45, and the spring 41 is accommodated in the space around the mount pin receiver 45. It is supported so as to be movable in the front-rear direction in conjunction with the arm portion 32 of the back support rod 5. That is, in the case of this embodiment, the bottom portion 49 of the movable member 34 functions as a spring mount receiver.

Here, around the spring 41 of the backrest reaction force mechanism 50, as shown in FIG. A locking range adjustment mechanism 51 for adjusting the locking range adjustment mechanism 51 is arranged concentrically.

The locking range adjustment mechanism 51 moves in the axial direction of the spring 41 in conjunction with the locking of the backrest 4 by coming into contact with a member (back support rod 5 in this embodiment) that is coupled to the backrest 4. It has a movable member 34 and a switching member 33 held by the main frame 2 so as to be immovable in the axial direction and rotatable around the axis, and the switching member 33 and the movable member 34 are coaxially arranged with the spring 41. The switching member 33 and the movable member 34 are arranged to face each other, and are configured to restrict movement of the backrest 4 by abutting the switching member 33 and the movable member 34. That is, by rotating the switching member 33, the minimum distance between the opposing end surfaces of the switching member 33 and the movable member 34 is made variable, and by abutting the minimum distance portions, movement of the interlocking member/back support rod 5 is prevented. The locking range of the backrest 4 is regulated, and the distance between the minimum distance parts is widened to allow the backrest 4 to lock.

In the case of this embodiment, one of the switching member 33 and the movable member 34, for example, the movable member 34, is formed with a convex portion 37 that protrudes in the axial direction, and the other, for example, the switching member 33 is formed with an end surface (perpendicular An end surface) 35 and a recess 36 into which the protrusion 37 enters are formed, and the protrusion 37 abuts the end surface 35 of the other member to prevent the movable member 34 from moving in the axial direction, thereby changing the locking range of the backrest 4. On the other hand, the movable member 34 can be moved in the axial direction at the position where the convex part 37 enters the concave part 36, thereby making it possible to lock the backrest 4. That is, by rotating the switching member 33, either the recess 36 or the perpendicular end face 35 of the rotation switching member 33 is placed in front of the protrusion 37 of the movable member 34, thereby releasing or restricting locking. It has a structure that can be switched.

The switching member 33 switches the position where the convex portion 37 of the movable member 34 abuts, in other words, the position where the movable member is prevented from moving or the range in which it can move back and forth. In the case of this embodiment, the switching member 33 has at least two stages (two stages between the tip surface 35 and the bottom surface 36a of the recess 36), preferably three stages (three stages between the end surface 35 and the bottom surfaces 36a and 36b of the recess 36). The above-mentioned contact surfaces are set. For example, in the case of this embodiment, as shown in FIG. It is provided so as to restrict the movement of the movable member 34 that moves closer. That is, when the convex part 37 protruding in the axial direction of the movable member 34 hits the innermost part (bottom surface 36a) of the recessed part 36 of the switching member 33, the amount of axial displacement becomes the largest, and when it comes into contact with the tip end surface 35. The amount of axial displacement becomes the smallest when the axial displacement occurs, and further reaches the intermediate axial displacement when it hits the intermediate step (bottom surface 36b). Furthermore, before the convex portion 37 of the movable member 34 abuts against the innermost part (bottom surface 36a) of the recess 36 of the switching member 33, the end surface 35 of the switching member 33 and the end surface 40 of the movable member 34 abut against each other, causing the backrest to lock. You may also try to prevent this.

In the case of the present embodiment, the switching member 33 has a cylindrical structure through which the spring 41 and the front spring mount 42 pass, and has a switching operation means 39 (for example, an operation lever 39 _L ) protruding outward in the radial direction from the circumferential surface. It is provided inside the main frame 2 as shown in FIG. The main frame 2 is provided with a window 16 in the side wall 27 for allowing the operating lever _39L to pop out, and the switching member 33 is opened by operating the switching lever _39L that penetrates the window 16 and protrudes outside. A rotation is performed. The switching member 33 includes four longitudinal protrusions 19 formed on the inner surface of the side wall portion 27 and a pair of front and rear arcuate rails (recesses) 17 that cross in the width direction between the left and right protrusions 19. It is accommodated in a space partitioned between the two, and is rotatably held by a presser plate 22.

The holding plate 22 is, for example, a rectangular frame member having a hollow part in the center when viewed from above, and is designed to surround the vicinity of the top of the cylindrical switching member 33 lying on the bottom wall part 26 of the main frame 2. and is fixed with bolts 25 screwed into female threads 20 of the four protrusions 19 of the side wall portion 27 of the main frame 2. The switching member 33 is rotatably supported by the bottom wall portion 26, the protrusion 19, and the presser plate 22 of the main frame 2, and is positioned in the axial direction, the width direction, and the height direction. The backrest reaction force mechanism 50 is stably held.

As shown in FIG. 8, on the back side of the presser plate 22, an arcuate rail (recess) 17 is provided along the circumferential surface of the switching member at a position where the front and rear edges of the switching member come into contact. A crescent-shaped stepped portion 18 is formed. Therefore, the edge of the cylindrical switching member 33 accommodated inside the arcuate rail (recess) 17 formed in the bottom wall portion 26 of the main frame 2 and the substantially crescent-shaped stepped portion 18 The parts are hooked and supported to allow smooth rotation while preventing movement in the front-back direction, left-right direction, and up-down direction.

In the case of this embodiment, the locking range adjustment mechanism 51 makes the minimum distance between the opposing end surfaces 35 and 38 of the switching member 33 and the movable member 34, which are disposed coaxially and facing the compression spring 41, variable. When the opposing end surfaces 35 and 38 come into contact, the movement of the back support rod 5 and thus the backrest 4 is blocked, and when the convex portion 37 is switched to a position where it can enter the concave portion 36, a convex portion is formed on the bottom surface 36a or 36b of the concave portion. The movable member 34 is allowed to move, in other words, the back support rod 5 and the backrest 4 are allowed to move until the movable member 37 comes into contact.

Therefore, the spring 41 supported between the front spring mount 42 passing through the switching member 33 and the rear spring mount 43 integrated with the movable member 34 expands and contracts due to the swinging of the back support rod 5, thereby increasing the spring force. It is attached to the back support rod 5. On the other hand, the switching member 33 is rotated by rotating the operating lever 39 _L toward the locking restriction position, so that the tip 38 of the convex portion 37 of the movable member 34 is switched from the end surface 35 of the switching member 33 to the position of the concave portion 36. . As a result, the minimum distance between the opposing end surfaces 36a or 36b and 38 of the switching member 33 and the movable member 34 is widened, so that the spring can be further compressed. In other words, the backrest is closed until the minimum distance between the switching member 33 and the movable member 34, for example, the tip surface 38 of the convex part 37 of the movable member 34 and either the bottom 36a or 36b of the recess 36 of the switching member 33 abut against each other. Allows locking. That is, the locking range adjustment mechanism 51 enters the locking restriction released state.

On the other hand, when the backrest 4 is returned to the initial position (the movable member 34 is in the most retracted position), the movable member 34 is rotated by rotating the operating lever _39L toward the locking restriction position. 34 is switched to a position where the tip surface 38 of the protrusion 37 contacts the end surface 35 of the switching member 33, and the tip surface 38 of the protrusion 37 is shifted from the position of the recess 36 and comes into contact with the end surface 35 of the switching member 33. As a result, there is almost no gap between the switching member 33 and the movable member 34, and the spring 41 can hardly be compressed. In other words, the locking is restricted. Note that the movable member 34 moves back and forth in conjunction with the movement of the arm portion 32 of the back support rod 5 by the force of the spring 41, so that it retreats when the backrest 4 returns to its initial position.

Here, the concave portion 36 of the switching member 33 or the convex portion 37 of the movable member 34 can be set in stepwise depths or heights, thereby not only regulating locking at the initial position but also in two stages including an intermediate position. It is also possible to provide the above locking restriction positions. For example, as shown in FIG. 5, when the movable member 3 The amount of axial displacement is the largest when the convex portion 37 protruding in the axial direction fits into the innermost part of the recess 36 of the switching member 33, and the amount of axial displacement is the smallest when it comes into contact with the surface of the shaft end face. Furthermore, when fitted to the intermediate stepped portion, the amount of axial displacement is medium.

In the above-described embodiment, the operating lever _39L , which is the operating means of the switching member 33, is structured to protrude outward from the window 16 formed in the side wall portion 27 of the main frame 2, that is, it is of a horizontal operation type. For example, as shown in FIGS. 9 and 10, the operating lever _39L of the switching member 33 may be configured to protrude outward from the window 16 formed in the bottom wall portion 26 of the main frame 2, i.e., a lower operating type. Also good. In this case, the main structures of the switching member 33 and the movable member 34 are the same, except for the position of the window 16 on the bottom wall 26 of the main frame 2 and the mounting position of the operating lever _39L relative to the switching member 33. , detailed explanation will be omitted.

Further, the switching operation means ₃₉ is not limited to the case where it protrudes from the side surface or the bottom surface of the main frame 2 as described above. For example, as shown in FIGS. It is also possible to have a structure in which the part 30 protrudes and is operated from the front. Of course, in this case, a disc-shaped knob-type operating means as shown in the figure, ie, an operating knob _39N , may be used, but instead of this, a lever may be provided, and the switch may be made by distributing (rotating) the lever to the left or right. Also good.

In this embodiment, the main frame 2 is provided with a partition wall 28 that receives and supports the front end of the spring 41, and a front wall 30 that prevents the switching member 33 from moving in the axial direction, as shown in FIG. The partition wall portion 28 is provided with a hole 29 through which the switching member 33 passes, and the front wall portion 30 is provided with a hole 31 that prevents the switching member 33 from passing through although the connecting shaft/screw (not shown) of the operation knob _39N is passed through. is provided. The holes 31 and 29 are arranged coaxially with each other, and the operation knob 39 _N is inserted through the main frame 2 with the front end surface of the switching member 33 that has passed through the partition wall section 28 in contact with the inner wall surface of the front wall section 30 . It can be installed by That is, as shown in FIGS. 14 and 15, the switching member 33 of this embodiment has a rod shape that penetrates the partition wall 28 and comes into contact with the front wall 30, and is operated at the front end through the hole 31 of the front wall 30. By screwing in the knob _39N , it is assembled to the main frame 2 so as to be immovable in the axial direction and rotatable around the axis.

Therefore, the backrest reaction mechanism 50 of this embodiment includes a reaction spring, for example, one compression coil spring 41, a rear spring mount 43 disposed at the rear end, and a front spring mount that supports the front end of the compression coil spring 41. The back support is composed of the partition wall part 28 of the main frame 2 that functions as a back support and a mount pin 44 for preventing buckling of the spring 41, and is linked with the partition part 28 of the main frame 2 through the rear spring mount 43. It is attached between the arm part 32 of the rod 5, and generates a force in the spring 41 to push back the backrest in conjunction with the backward tilt of the backrest.

Here, the locking range adjustment mechanism 51 is incorporated inside the spring 41, as shown in FIG. This locking range adjustment mechanism 51 is configured, for example, as in the above-described embodiment, by a combination of a movable member 34 having a convex portion 37, a switching member 33 having an end surface 35 facing the convex portion 37, and a concave portion 36, By rotating the switching member 33 by a predetermined angle, the concave portion 36 (locking restriction release position) or the end face 35 (locking restriction position) is selectively arranged in front of the convex portion 37 of the movable member 34. In the present embodiment, the locking restriction position where the convex portion 37 of the movable member 34 and the end surface 35 of the switching member 33 butt each other is, for example, when the backrest 4 is returned to the initial position (the movable member 34 is the most retreated position). position) or the position immediately before it (bottom surface 36a of the recess 36), but it is not particularly limited to this, and it may be only the initial position, or multiple positions other than that, or both the initial position and multiple positions. It may be included.

The switching member 33 of this embodiment has a rod shape, and the end face facing the movable member 34 is formed into a cylindrical shape to form an end face 35 and a recess 36, and a mount pin 44 is inserted into the bottom of the cylindrical part. A hole (not shown) is provided to support the tip of the mount pin 44. Therefore, the mount pin 44 is held between the rear spring mount 43 integrated with the movable member 34 and the switching member 33, while the spring 41 is held between the rear spring mount 43 and the partition wall 28 of the main frame 2. Supported.

According to the locking range adjustment mechanism 51 of this embodiment, when the operation knob _39N is rotated to the locking restriction position side, the recess 36 of the switching member 33 is disposed in front of the protrusion 37 of the movable member 34, and the convex 37 can enter into the recess 36. As a result, the distance between the switching member 33 and the movable member 34 at the minimum distance portion increases, so that the spring 41 can be moved in the direction of further contracting. That is, the locking of the backrest is in a locking restricted state.

On the other hand, when the operation knob _39N is rotated to the locking restriction position side, the recess 36 of the switching member 33 comes off from the front of the protrusion 37 of the movable member 34 and switches to the end surface 35, so that the end surface 35 of the switching member 33 and the movable The gap between the member 34 and the convex portion 37 is almost eliminated, and the spring 41 can hardly be compressed. That is, the locking of the backrest is regulated at the initial position. Further, when switching is made to the bottom/end surface 36a in the middle of the recess 36, the locking restriction position state is switched to the middle position where the spring 41 cannot be compressed any further.

According to the locking range adjustment mechanism 51 configured as described above, by configuring the backrest reaction force mechanism 50 and the locking range adjustment mechanism 51 on the same axis, the backrest reaction force mechanism 50 and the locking range adjustment mechanism 51 While providing these two mechanisms, it is possible to reduce the space under the seat, reduce manufacturing costs, and improve the appearance.

Note that although the form of the spring support structure described above is an example of a preferred form of the present invention, it is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the recess 36 is provided on the switching member 33 side, and the protrusion 37 is provided on the movable member 34 side, but the structure is not limited to this, and the protrusion 37 is provided on the switching member 33 side. , a recess 36 may be provided on the movable member 34 side.

Further, in the above-described embodiment, a plurality of stepwise bottom portions 36a and 36b are formed in the recess 36, thereby making it possible to restrict locking not only at the initial position but also during the locking operation. Instead, a plurality of locking restriction positions may be created by providing a step in the convex portion 37. Further, in the above-described embodiment, the locking range adjustment mechanism 51 includes locking regulation at the initial position, but this is not particularly limited. It's okay.

In the above-described embodiment, an example is given in which the reaction force applying mechanism 50 using the spring 41 is applied, but the chair to which the present invention is applied is not particularly limited to this, and a weight-adaptive reaction force mechanism 50 is used. A chair that has only one of the synchronized rocking mechanisms that uses both a force applying mechanism and a reaction force applying mechanism that has a coil spring, or for example, a chair that has only one of them applied to a synchronized rocking mechanism that combines a force applying mechanism and a reaction force applying mechanism that has a coil spring, or for example, a chair that moves backwards in conjunction with the backward tilt of the backrest. It can be applied to a non-weight-sensing synchronized rocking mechanism in which the end side sinks, a locking mechanism in which only the backrest tilts backwards, or a locking mechanism in which only the seat performs a rocking motion, and even chairs that do not have a locking mechanism. It goes without saying that there is. Further, the specific shapes and aspects of each component such as the main frame 2, seat 3, and backrest 4 to which the present invention can be applied are not limited to those in the above-described embodiments, and are not limited to the use and design of the chair. The selection will be made as appropriate based on the following factors.

1 Legs 2 Main frame 3 Seat 4 Backrest
5 Back support rod (member that works with the backrest)
6 Backrest rotation shaft 7 Backrest support member 8 Back frame 9 Back plate 10 Back mounting seat 11 Support shaft 16 Window 32 Arm portion 33 Switching member 34 Movable member 35 End surface 36 Recess 36a Bottom surface of recess 36b Bottom surface 37 of step of recess Convex portion 38 End face 39 of convex portion Rotation operation means 39 _L operation lever 39 _N operation knob 41 Spring 42 Front spring mount 43 Rear spring mount 44 Mount pin 45 Mount pin receiving portion 46 Spring mount receiving portion 47 Bearing portion 50 Backrest reaction force mechanism 51 Locking range adjustment mechanism

Claims (8)

In a locking range adjustment mechanism that regulates the locking range of the backrest of a chair with a locking function that allows the backrest to fall backward,
a backrest reaction force mechanism that uses a spring to generate a force between the main frame and a main frame to push back the backrest in conjunction with the backward tilt of the backrest, and to apply it to a member that works with the backrest;
a locking range adjustment mechanism arranged concentrically with the spring of the backrest reaction force mechanism;
The locking range adjustment mechanism includes a movable member that moves in the axial direction of the spring in conjunction with locking of the backrest by coming into contact with a member that moves with the backrest, and a movable member that is not movable in the axial direction and that moves in the axial direction of the spring in conjunction with the locking of the backrest. a switching member rotatably held by the main frame around the main frame;
The switching member and the movable member are arranged coaxially with the spring and facing each other, and the minimum distance between the opposing end surfaces of the switching member and the movable member is variable by rotation of the switching member, The locking of the backrest is restricted by blocking the movement of the interlocking member by abutting the minimum distance portions, and the locking of the backrest is permitted by widening the distance between the minimum distance portions. Chair back locking range adjustment mechanism. A convex portion protruding in the axial direction is formed on one of the mutually opposing end surfaces of the switching member or the movable member, and a concave portion into which the convex portion enters is formed on the other, and the convex portion is connected to the other member. The movable member is prevented from moving in the axial direction by coming into contact with the end face of the movable member, thereby regulating the locking range of the backrest, while allowing the movable member to move in the axial direction at a position where the convex portion enters the recess. 2. The chair back locking range adjustment mechanism according to claim 1, wherein the backrest can be locked as follows. The end surface of the movable member is provided with the protrusion, and the end surface of the switching member is provided with the recess, and the tip surface of the protrusion abuts against the end surface of the switching member to prevent its movement. It functions as an end face, and is characterized in that locking is released or restricted by switching the position of either the concave portion or the perpendicular end face to the front of the convex portion of the movable member by rotating the switching member. The chair back locking range adjustment mechanism according to claim 2. 4. The chair back locking range adjustment mechanism according to claim 1, wherein the locking restriction position is an initial position. The chair back locking range adjusting mechanism according to any one of claims 1 to 4, wherein the locking range adjusting mechanism is disposed outside the spring and covers the spring. The locking range of a chair backrest according to any one of claims 1 to 5, characterized in that the switching member is provided with a rotational operation means that penetrates the main frame and protrudes to the outside on an outer circumferential surface or a front end surface of the switching member. Adjustment mechanism. The movable member includes a spring mount receiver that supports the rear end of the spring of the backrest reaction force mechanism, a bearing portion that swingably engages with a member that interlocks with the backrest, and a mount pin that holds the mount pin. 6. The chair back locking range adjustment mechanism according to claim 5, further comprising a receiving portion and also serving as a rear spring mount. A chair incorporating the backrest locking range adjustment mechanism according to any one of claims 1 to 7.

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