JPH1075845A - Chair lumbar support - Google Patents

Abstract

(57) [Summary] [Problem] To improve operability and not to impair the appearance. SOLUTION: In a lumbar support 6 for projecting a part of a backrest 1 of a chair toward an occupant's waist by an arbitrary amount, a support swingably attached to a shell member of the backrest 1, for example, an inner shell 3. An area 10e in which a displacement is provided from the back side of the support plate 7 to rotate the plate 7 in one direction to protrude the support plate 7 to the front side, and at least a cam displacement is provided when rotating from the maximum cam displacement to the minimum cam displacement. And a ratchet mechanism 9 for rotating the cam mechanism 8 in one direction by a fixed amount at a time.
And an operating means, such as an operating lever 17, which is arranged away from the center line of the backrest and within reach of the user while sitting down, and which drives the feed claw 20 of the ratchet mechanism 9. Also,
In particular, a cam mechanism which does not require a stepwise cam displacement is rotated by a worm and a worm wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved chair backrest. More specifically, the present invention relates to a lumbar support that projects a part of the backrest by an arbitrary amount toward the waist of a person sitting on a chair.

[0002]

2. Description of the Related Art In order to reduce the burden on the lumbar spine and the pressure on the abdomen of a seated person when sitting on a chair for a long time, a backrest having a lumbar support in which a portion of the backrest protrudes forward has been developed. ing. There is also known a lumbar support that can adjust the amount of protrusion from the backrest to the front side in order to correspond to the body shape and sitting posture of the seated person. For example, a chair having a built-in airbag in a portion of a backrest against which a seated person's waist contacts is commercially available. In this chair, the air bag is inflated by a manual air pump attached to the lower side of the seat portion, and the cushion and the upper fabric are projected so as to press against the waist.

[0003]

However, in the lumbar support described above, the operability is poor because the pumping operation of the air pump must be performed to adjust the amount of protrusion. In addition, since the air pump must be arranged, for example, below the seat, the appearance is impaired. Further, since the expansion rate of the airbag changes depending on the temperature, the airbag must be frequently adjusted by pumping in order to maintain the amount of protrusion. Further, the airbag is easily damaged by external factors, and may become unusable if it is stabbed with, for example, a needle.

Accordingly, an object of the present invention is to provide a lumbar support which is excellent in operability, does not impair the appearance, and has a very small change in the protrusion amount due to temperature and is hardly damaged.

[0005]

SUMMARY OF THE INVENTION In order to achieve this object, a first aspect of the present invention is a lumbar support for projecting a part of a backrest of a chair toward an occupant's waist by an arbitrary amount. A support plate swingably attached to the shell member of the above, and applying a displacement from the back side of the support plate that rotates in one direction and projects the support plate to the front side, and rotates at least from the maximum cam displacement to the minimum cam displacement. A cam mechanism in which areas where a cam displacement is given and areas where a cam displacement is not given are alternately given a stepwise cam displacement, a ratchet mechanism for rotating the cam mechanism by a fixed amount in one direction, and a seated state And operating means for driving the feed pawl of the ratchet mechanism, which is arranged within a reach of the ratchet mechanism.

Accordingly, when the ratchet mechanism is driven by operating the operating means in a state where the cam displacement of the cam mechanism is minimum, the cam mechanism is rotated by a fixed amount in one direction, that is, the direction in which the cam displacement is increased. Since the support plate is displaced so as to protrude to the front side, the cushion of the backrest and a part of the upholstery are pushed out by the support plate by an amount corresponding to the displacement amount of the cam mechanism and pressed against the waist of the seated person. Here, a reaction force such as the elasticity of the cushion or the upholstery ground acts on the cam mechanism, but the ratchet mechanism prevents the reverse rotation of the cam mechanism. Since the ratchet mechanism prevents reverse rotation at every predetermined rotation angle of the cam mechanism, the support plate is fixed at every predetermined cam displacement.

Further, when the cam mechanism reaches a maximum by further rotating the cam mechanism by the operating means, the cam displacement thereafter decreases and returns to the original state. At this time, a rotational force is given to the cam mechanism by a support plate pushed back by the reaction force of the cushion and the upholstery or the weight of the seated person. Since the rotation direction is the same as the rotation direction by the ratchet mechanism, the cam mechanism is rotated in a direction in which the support plate is retracted. However, since the reaction force of the cushion etc. is stably supported in the area where the cam displacement is not given even if the cam mechanism rotates to some extent, the cam mechanism does not rotate to the minimum cam displacement at a stretch due to the reaction force, and the impact noise Can be prevented from occurring.

Further, the movement of the operating means having a small width exposed outside the backrest is converted into the rotational momentum of the cam mechanism by the feed mechanism, and when the cam displacement is increased, the cam mechanism is moved by the ratchet mechanism at a constant angle. When the cam displacement is reduced, the cam mechanism is rotated at every rotation angle located in a region where the cam displacement is not given.

Here, since the operating means is arranged so as to be exposed within the reach of the user in a seated state, the amount of protrusion of the support plate can be adjusted continuously with only one hand without changing the operating means in the seated state. It can be carried out. In particular, the installation location of the operating means is not limited, but when installed at a position deviated from the center line of the backrest, the operability is improved.

According to a second aspect of the present invention, there is provided a lumbar support for a chair, comprising: a cam mechanism having an end face cam and a follower having a cam contact surface which is coaxially opposed to the end face cam, and has a reverse cam surface with respect to the end face cam. It consists of. In this case, simply by rotating the end face cam, the follower protrudes coaxially, and further protrudes the support plate in front of it.

Further, the lumbar support of the chair according to claim 3, wherein the cam surface when the cam displacement of the cam mechanism changes from the minimum to the maximum is such that the cam surface per rotation angle of the cam mechanism as the cam displacement changes from the minimum to the maximum. It is formed into a curved surface shape in which the amount of change in cam displacement gradually decreases.

In this case, when the cam displacement of the cam mechanism is close to the minimum, the reaction force of the cushion or the like acting on the support plate is small, and when the cam displacement is close to the maximum, the reaction force acting on the support plate is large. As the cam displacement changes from the minimum to the maximum, the change amount of the cam displacement per rotation angle of the cam mechanism gradually decreases, so that the force for rotating the cam mechanism, that is, the operation force for driving the feed mechanism, is almost constant. Can be large.

According to a fourth aspect of the present invention, there is provided a lumbar support for projecting a part of a backrest of a chair toward an occupant's waist by an arbitrary amount, wherein the support is swingably attached to a shell member of the backrest. Plate, a cam mechanism provided on the back side of the support plate to give a displacement to project the support plate to the front side, a worm wheel coaxially rotated with the cam mechanism, a worm meshed with the worm wheel, and connected to the worm And a rotating means which is disposed in a state where the user can reach it while sitting down.

Therefore, when the worm is rotated by rotating the rotating means, the worm wheel is rotated, and the cam mechanism is driven, a displacement for projecting the support plate to the front side is given, so that an amount corresponding to the displacement of the cam mechanism is provided. Only the cushion of the backrest and a part of the upholstery are pushed out by the support plate and pressed against the waist of the seated person. In addition, if the rotating mechanism is rotated in the opposite direction to reverse the cam mechanism, the amount of projection of the cam mechanism with respect to the support plate is reduced, and the support plate is pushed back by the reaction force of the cushion and the upholstery and the weight of the seated person. As a result, the pressing force against the waist of the seated person is reduced.

Here, the reaction force due to the resilience of the cushion or the like tries to rotate the cam mechanism via the support plate.
Since the cam mechanism is connected to the worm wheel, the cam mechanism does not rotate due to the reaction force. Thereby, the reverse rotation of the cam mechanism due to the reaction force is prevented.

Further, the rotation of the rotating means exposed outside the backrest is converted into the rotational momentum of the cam mechanism required to obtain the amount of protrusion required for the lumbar support by the worm and the worm wheel. Let it. Therefore, it is possible to continuously project the support plate with only one hand without changing the rotation means while sitting, and adjust the amount of projection.

According to a fifth aspect of the present invention, the lumbar support comprises a cam mechanism comprising an end cam and a follower having a cam contact surface which is coaxially opposed to the end cam and has a reverse cam surface. It is assumed. In this case, simply by rotating the end face cam, the follower protrudes coaxially, and further protrudes the support plate in front of it.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings. 1 to 5 show an embodiment in which the lumbar support of the present invention is applied to a backrest of a swivel chair. In this specification,
Unless otherwise specified, the front-back direction refers to the depth direction of the chair, the rear or back side means the backrest side, and the front or front side means the front edge side of the seat. Also,
The left-right direction refers to the width direction of the chair.

As shown in FIGS. 1 to 3, the backrest 1 of the present embodiment includes an outer shell 2 serving as a back cover of the backrest 1, an inner shell 3 serving as a core material of the backrest 1, and an upper covering. It is composed of a ground 4, a cushion 5, and a lumbar support 6. A cushion 5 is attached to the front surface of the inner shell 3, and the front surface of the cushion 5 is further covered with an upholstery 4. The periphery of the upper covering material 4 is, for example, wrapped around from the periphery of the inner shell 3 to the rear side and is fixed.
The material of the upholstery 4 is preferably cloth, leather, vinyl, or the like, but is not limited thereto and may be a known or new material. The material of the cushion 5 is preferably, for example, urethane or sponge, but is not limited to these.

On the back side of the inner shell 3, the outer shell 2 is covered. The inner shell 3 and the outer shell 2 are joined by engagement of a not-shown locking claw and a locking hole formed at portions where the members face each other. The inner shell 3 and the outer shell 2 are integrally formed by injection molding of plastic. However, the material of these shells 2 and 3 is not limited to plastic, but may be metal or other materials.

The lumbar support 6 includes a support plate 7 swingably mounted on the inner shell 3 as a shell member, and a cam mechanism 8 provided on the back side of the support plate 7.
And a ratchet mechanism 9 for regulating the rotation direction of the cam mechanism 8
An operating lever 17 as operating means exposed on one side of a lower portion of the backrest 1; and a feed claw 20 of the ratchet mechanism 9
And a feed mechanism 12 that rotates the ratchet gear 15 in cooperation with the operation lever 17. In this embodiment, the cam mechanism 8 includes an end cam 10 and a driven cylinder 11 as a driven joint. In this embodiment, the driven cylinder 11 is provided between the end face cam 10 and the support plate 7.
Is installed.

The support plate 7 is attached to the center of the inner shell 3. The support plate 7 has a T-shape inverted upside down. In the case of the present embodiment, the inner shell 3 and the support plate 7 are integrally formed by injection molding of plastic. A gap is formed between the support plate 7 and the inner shell 3 except for the hinge portion 7c, and only the support plate 7 is deformably supported so as to protrude from the inner shell 3.

In this embodiment, since the inner shell 3 and the support plate 7 are integrally formed, the number of parts does not increase. However, the present invention is not limited thereto, and the inner shell 3 and the support plate 7 may be formed separately, fixed with screws or the like, and integrated. For example, a metal support plate 7 may be attached to the inner shell 3 made of plastic, plywood, metal, or the like via a hinge or the like. In this case, the support plate 7 can be made more rigid. Further, the support plate 7 may be attached to the outer shell 2 by a hinge or the like. In this case, even if the inner shell 3 and the outer shell 2 are not assembled, a change in the amount of protrusion of the support plate 7 due to the operation of the lumbar support 6 can be confirmed.

The support plate 7 of this embodiment includes a support portion 7a, a connecting portion 7b for supporting the support portion 7a, and a hinge portion 7c for connecting the connecting portion 7b to the inner shell 3 with flexibility. It has. Support section 7a
Has a shape suitable for supporting the waist, for example, a curved surface shape which is horizontally long and whose central portion in the vertical direction projects toward the cushion 5 and is curved. This protruding part is the cushion 5
And, it is pressed against the waist of the seated person via the upper covering 4.

The connecting portion 7b has a substantially flat plate shape, and its upper end is integrated with the inner shell 3. A vertically long rectangular engaging hole 7d is formed in the center of the connecting portion 7b. An engagement protrusion 11c at the tip of the driven cylinder 11 is fitted into the engagement hole 7d. Therefore, the connecting portion 7b prevents the driven cylinder 11 from rotating.

A ridge having a longitudinal direction in the left-right direction is formed at an upper portion of the connecting portion 7b to form a hinge portion 7c. As described above, since the connecting portion 7b is made of plastic and has the hinge portion 7c at the upper portion, the support plate 7 can protrude from the inner shell 3 by elastic deformation. Further, in the present embodiment, since the connecting portion 7b is made of plastic, when a large load is applied to the support portion 7a, the connecting portion 7b is driven by the driven cylinder 11 of the cam mechanism 8.
The support plate 7 is prevented from being damaged by bending with the head of the support plate as a fulcrum.

On the back side of the support plate 7, a not-shown rib for reinforcement is formed. For this reason, even if the connecting portion 7b is protruded from the rear side by the cam mechanism 8,
The support portion 7a does not bend with respect to the connecting portion 7b due to the load applied to the waist of the seated person. Therefore, it is not necessary to arrange the cam mechanism 8 immediately behind the support portion 7a in order to increase the load resistance, and the cam mechanism 8 is arranged behind the connecting portion 7b to amplify the cam displacement and support the cam mechanism. The protrusion amount of the portion 7a can be increased.

On the other hand, the cam mechanism 8 comprises an end cam 10 and a driven cylinder 11 disposed coaxially and opposed to the end cam 10. As shown in FIG. 4, a coaxial ratchet gear 15 is fitted and integrated with the outer peripheral surface of the cylindrical end face cam 10, and these are rotated together. The end cam 10 is rotatably fitted on the outer periphery of a cylindrical cam receiver 13 formed on the front surface of the outer shell 2. A hole 13 having a circular cross section is formed in the center of the cam receiver 13.
a is formed, and the shaft portion 14 of the driven cylinder 11 is slidably inserted.

As shown in FIG. 4 and FIG. 5, a cam surface 10
a and the cam contact surface 11a are formed respectively. The cam surface 10a is formed such that the maximum position and the minimum position of the cam displacement are shifted by 180 degrees in rotation angle.
In a region 10b where the driven cylinder 11 is guided when the cam displacement increases, the cam surface 10a has a slightly expanded curved surface. Therefore, when the reaction force of the cushion 5 or the occupant to the support plate 7 is small near the minimum cam displacement, the change of the cam displacement with respect to the rotation angle is large, and conversely, the support plate by the cushion 5 or the like near the maximum cam displacement. When the reaction force to the cam 7 is large, the change of the cam displacement with respect to the rotation angle becomes small, so that the force for rotating the end face cam 10, that is, the operating force can be kept constant.

In the present embodiment, the end face cam 10 is
The inclination of the cam surface 10a is formed such that the cam displacement of the cam mechanism 8 increases steplessly and then decreases stepwise when rotating in the counterclockwise rotation direction as viewed from one side. Of course, the present invention is not particularly limited to this, and a stepwise cam surface may be formed in the direction in which the cam displacement increases, so that a stepwise cam displacement may be applied over the entire area.

On the other hand, when the cam displacement decreases, the driven cylinder 11
Is guided in the area 10c, the cam surface 10a
0d and the slope 10e are alternately continuous. In this area 10c, when the driven cylinder 11 is guided to the horizontal plane 10d, the driven cylinder 11
Does not move. At this time, the reaction force to the support plate 7 is supported between the horizontal surface 10d and the cam contact surface 11a. Further, the height of the horizontal plane 10d is made equal to the height of the cam surface 10a in a region 10b separated by the same rotation angle about the position where the cam displacement is the maximum or minimum.

In this embodiment, the cam surface 1 in the area 10b where the driven cylinder 11 is guided when the cam displacement increases.
0a is curved, but is not limited to this.
The cam surface 10a at 0b may be formed stepwise.
According to this, the reaction force when the cam displacement increases can also be received on the horizontal plane, and the load on the ratchet mechanism 9 can be reduced.

Further, the cam contact surface 11a of the driven cylinder 11
The concave and convex portions of the end face cam 10 are formed in reverse to the cam surface 10a. Therefore, when the cam displacement of the cam mechanism 8 is 0, the cam contact surface 11a is in close contact with the cam surface 10a of the end cam 10, so that the stability of the cam mechanism 8 is improved.

The follower is not particularly limited to a cylindrical one having an annular cam contact surface 11a, and a rod-like follower may be employed. Further, the end face cam 10
The position relationship between the end face cam 10 and the driven cylinder 11 may be reversed to move the end cam 10 side in the axial direction so that the support plate 7 protrudes toward the waist. Further, as the cam mechanism 8, a swash plate cam may be employed in addition to the above-described end cam, and in some cases, an inverted cam may be employed.

At the end of the driven cylinder 11 opposite to the cam contact surface 11a, there is formed an engagement projection 11c having a substantially semicircular plate shape and a curved surface facing the support plate 7. The engagement protrusion 11c is fitted in the engagement hole 7d of the support plate 7 with a gap. Therefore, the driven cylinder 11 cannot rotate with respect to the support plate 7. Further, inside the driven cylinder 11, a cylindrical shaft portion 14 that forms a gap / hole 11b with the inner peripheral surface is integrated. The shaft portion 14 protrudes from the cam contact surface 11a and has a hole 13a
Is slidably inserted in That is, the shaft portion 14 of the driven cylinder 11 is inserted into the hole 13 a of the cam receiver 13, and the cam receiver 13 is inserted into the hole 11 b inside the driven cylinder 11.

In the present embodiment, the end cam 10 and the driven cylinder 11 are disposed on the rear side of the connecting portion 7b of the support plate 7, so that the end cam 10 and the driven cylinder 11 are provided at a position close to the hinge portion 7c which is the center of swing of the support plate 7. Therefore, the protrusion amount of the support plate 7 can be made larger than the protrusion length of the driven cylinder 11. Therefore, the support plate 7 can be largely protruded by a slight movement of the driven cylinder 11, thereby improving the operability. That is, even if the angle of rotation of the end cam 10 by one operation of the feed mechanism 12 is relatively small, the support plate 7 can be largely protruded to the front side, so that the operation amount of the occupant is small and sufficient. .

As shown in FIGS. 1 to 3, the ratchet mechanism 9 includes a ratchet gear 15, a detent pawl 16 and a feed pawl 20. Eight engaging claws 15a are formed on the outer peripheral surface of the ratchet gear 15 every 45 degrees. In the present embodiment, each engagement claw 15a is
It is formed so as to have a surface facing clockwise as viewed from the side.

The detent claw 16 is rotatably mounted on the mounting projection 2a of the outer shell 2, and is swingable about a position substantially on a tangent to the ratchet gear 15 and toward the engagement claw 15a. . And the detent claw 16
Is made engageable with the engaging claw 15a. Further, between the detent pawl 16 and the outer shell 2, an urging spring 18 formed of a torsion coil spring is attached. The urging spring 18 urges the detent claw 16 in a direction to contact the ratchet gear 15. For this reason, when the ratchet gear 15 rotates clockwise as viewed from the driven cylinder 11 side, the detent pawl 16 becomes the engaging pawl 15 every 45 degrees.
and cannot rotate. On the other hand, when rotating in the counterclockwise rotation direction, the detent claw 16 is
It can rotate freely without engaging with. That is, the cam can be freely rotated only in the rotation direction in which the cam displacement by the cam mechanism 8 increases steplessly and decreases stepwise.

Further, the feed mechanism 12 is provided on the surface of the ratchet gear 15 facing the outer shell 2 with a feed claw 2 which can be engaged with a feed pin 19 as a tooth surface provided at every 45 degrees.
0 and an urging spring 21. One end of the feed claw 20 is rotatably attached to one end of the operation lever 17 by a pin joint or the like. An urging spring 21 composed of a torsion coil spring is attached to a connection between the feed claw 20 and the operation lever 17. The urging spring 21 includes the feed claw 2
0 is urged in the direction of pressing the pin 19 of the ratchet gear 15.

The operating lever 17 is rotatably provided on the mounting projection 2b of the outer shell 2. Therefore, the feed pawl 20 is turned around the mounting protrusion 2b by the swing of the operation lever 17. Here, the position of the mounting projection 2b is determined by the fact that the feed pawl 20 is
5 is a position that slides substantially on a tangent line. And
The closer the mounting projection 2b is to the ratchet gear 15, the longer the operation side of the operation lever 17 is, so that the operation force can be reduced. On the other hand, the mounting projection 2b is
As the distance from the operation lever 17 increases, the operation side of the operation lever 17 becomes shorter, so that the operation stroke becomes shorter. The operation lever 17 is installed so as to protrude outside the outer shell 2 at a position away from the center line of the backrest, that is, at a position deviated from the center of the backrest. That is, since the operation lever 17 is not located directly behind the back of the seated person, the seated person can operate the operation lever 17 without lifting the back from the backrest. In addition, since the operation lever 17 is exposed only on one side of the backrest, the occupant can operate the operation means using only one hand. Therefore, operability can be improved. However, the position of the operation lever 17 is not particularly limited to the above-described position, and may be provided in a range where the hand can be reached in a seated state, or in some cases, a position where the user operates after standing.

A feed projection 20a is formed on the side of the feed claw 20 on the feed pin 19 side. Feeding claw 20
When the ratchet gear 15 is rotated counterclockwise when viewed from the driven cylinder 11 side, the feed projection 20a
A pressing surface 20b that is substantially perpendicular to the traveling direction of the feed pin 19 is formed in a portion where the feed pin 19 extends. Also, the feed projection 20
On the side opposite to the pressing surface 20b, a gentle slope 20c is formed. Therefore, in FIG. 3, when the feed claw 20 moves rightward, the pressing surface 20b presses the feed pin 19 to rotate the ratchet gear 15 by 45 degrees. Also,
In the drawing, when the feed pawl 20 moves to the left, the detent pawl 16 prevents the ratchet gear 15 from rotating in the clockwise direction, and the bevel 20c is guided along the feed pin 19 to feed the pawl. 20 deviates from the ratchet gear 15.

In this embodiment, since the ratchet gear 15 rotates 45 degrees by one feed operation, eight operations are required to rotate the cam mechanism 8 once. That is,
Four operations are required to project the support plate 7 from the lowest position to the highest position, and conversely, four operations are required to lower the support plate 7 from the highest position to the lowest position. In other words,
Four stages of adjustment are possible. However, the rotation angle of the ratchet gear 15 per operation can be changed by changing the number of the feed pins 19, the size of the ratchet gear 15, the moving length of the feed claw 20, and the like. . This makes it possible to set the number of times the support plate 7 is moved up and down. For example, the number of operations can be increased to reduce the amount of projection per operation.

A return spring 22 composed of a torsion coil spring is provided between the operation lever 17 and the outer shell 2. The return spring 22 urges the operation lever 17 in a direction opposite to the direction in which the feed pawl 20 rotates the ratchet gear 15. In the present embodiment, the operating lever 17 exposed to the outside of the backrest 1 is used as the operating means. However, the present invention is not limited to this. Any mechanism that moves the feed claw 20 substantially along the tangent to the ratchet gear 15 is used. A link mechanism or a gear train combining a plurality of links may be used.

Further, the lower end of the operation lever 17 protrudes from one side of the lower part of the outer shell 2. An operation knob 29 made of, for example, a plastic sphere is attached to the lower end. A cutout is formed in a portion of the lower surface of the outer shell 2 where the operation lever 17 protrudes. Thereby, contact between the operation lever 17 and the outer shell 2 is prevented.
In addition, in this embodiment, there is no member other than the operation knob 29 exposed to the outside of the backrest 1, so that the appearance of the chair is not impaired.

According to the lumbar support 6 configured as described above, a part of the backrest can be easily protruded toward the waist side by an arbitrary amount by operating as follows.

That is, in order to operate the lumbar support 6, one hand is turned to the rear one side while the back rests against the backrest 1, and the operation knob 29 and the operation lever 17 are moved sideways against the return spring 22. Move to Here, operation knob 29
Is exposed on one side of the lower portion of the backrest 1 so that a seated person can operate the back without lifting the back from the backrest 1. That is, when the operation knob 29 is located at the center of the lower part of the backrest 1, that is, right behind the back, the back must be lifted and operated, but according to the present embodiment, the operability is inferior. Never. Moreover,
Since the operation knob 29 is exposed on one side of the backrest 1, the occupant can perform the operation without changing the operation knob 29 from one hand to the other during the operation.

The operation of the operation knob 29 causes the operation lever 17 and the feed claw 20 to swing, and the feed projection 20a
The pressing surface 20b presses the feed pin 19 to rotate the ratchet gear 15. Since this rotation is counterclockwise as viewed from the driven cylinder 11, the rotation is not prevented by the ratchet mechanism 9.

With this rotation, the end face cam 10 rotates to give an axial displacement to the driven cylinder 11, and a part of the backrest protrudes toward the waist of the seated person. That is, the cam mechanism 8 pushes the connecting portion 7b of the support plate 7 forward at the tip of the driven cylinder 11. The support plate 7 is protruded forward while opposing the reaction force of the upper covering material 4 and the cushion 5 and the hinge portion 7c of the connecting portion 7b, and pushes a part of the backrest toward the waist.

Here, the reaction force of the cushion 5 and the like acts on the cam mechanism 8 in the direction in which the cam displacement is reduced, and tries to rotate the end face cam 10 in the opposite direction. However, since the ratchet mechanism 9 acts on the rotation in this direction, the end face cam 10 does not rotate in the opposite direction, and the amount of protrusion of the support plate 7 is maintained.

When the operator releases the operation knob 29 or weakens the operation force, the operation lever 17 is returned by the return spring 22. Thereby, the feed claw 20 is pulled back. At this time, since the inclined surface 20c of the feed projection 20a is guided along the feed pin 19, the feed claw 20 is once pulled away from the ratchet gear 15 against the urging spring 21 so as to be pulled back. Further, when the inclined surface 20c presses the feed pin 19, a rotational force in the clockwise direction in FIG. 3 is applied to the ratchet gear 15, but the detent claw 16 is engaged with the engagement claw 15a.
, The ratchet gear 15 is not rotated in that direction.

Each time the operation lever 17 is fed, the ratchet gear 15 is rotated by 45 degrees, and the cam displacement of the cam mechanism 8 is gradually increased. Here, in an ascending region (a region where the cam displacement increases due to the cam rotation) 10b in which the driven cylinder 11 is guided when the cam displacement increases, the cam surface 10a is a slightly bulged curved surface, The force for rotating the end face cam 10, that is, the operating force, can be kept constant irrespective of the increase in the reaction force due to the increase in the protrusion amount of.

Further, the cam displacement is gradually reduced after reaching the maximum position. Here, the height of the horizontal surface 10d of the cam surface 10a is the ascending region 10b separated by the same rotation angle about the position where the cam displacement is the maximum or minimum.
And the height of the cam surface 10a at the step 10c, the magnitude of the cam displacement, that is, the amount of protrusion of the support plate 7 is made equal between the ascending region 10b and the descending region (the region where the cam displacement is reduced by the cam rotation) 10c. be able to. That is, for example, the cam displacement before one operation at the maximum position of the cam displacement is equal to the cam displacement after one operation at the maximum position. Thereby, for example, when the user increases the amount of protrusion and exceeds the appropriate amount of protrusion, when the amount of protrusion decreases after passing the maximum displacement position, it can be re-installed at the appropriate amount of protrusion. it can. Accordingly, it is not necessary to rotate the end cam 10 once to obtain an appropriate protrusion amount, and operability can be improved.

After the cam displacement is reduced and reaches the minimum position, the cam displacement is gradually increased again. As described above, the amount of protrusion of the support plate 7 repeatedly increases and decreases due to the reciprocation of the operation lever 17.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the lumbar support 6 is applied to the backrest 1 having the shape shown in FIGS.
The shape of the backrest 1 is not limited to this.

For example, the lumbar support 6 of the present invention may be applied to a backrest 1 'having a shape as shown in FIG. In this embodiment, since the length from the cam mechanism 8 to the exposed portion of the operation knob 29 is longer than the backrest 1 shown in FIGS. 1 and 2, the operation lever 17 'is a longer member. A feed pin 19 is formed on the support plate 7 side of the ratchet gear 15 '. However, it goes without saying that the feed pin 19 used in the embodiment shown in FIGS. 1 to 5 may use the ratchet gear 15 formed on the outer shell 2 side. The other members are the same as the members of the embodiment shown in FIGS.

According to this embodiment, as in the backrest 1 ′ shown in FIG. 6, the distance between the installation position of the cam mechanism 8 of the outer shell 2 ′ and the exposed position of the operation knob 29 is relatively long. However, the lumbar support 6 can be mounted. Here, as for the constituent members other than the operation lever 17 ', each constituent member of the lumbar support 6 used for the backrest 1 shown in FIGS. 1 and 2 can be used, and common use can be achieved.

In each of the above-described embodiments, the lumbar support 6 includes the support plate 7, the cam mechanism 8, the ratchet mechanism 9, the operating means 17, and the feed mechanism 12. However, the present invention is not limited to this. As shown in FIG. 9, the support plate 7, a cam mechanism 30 provided on the back side of the support plate 7, a worm wheel 25 coaxially rotated with the cam mechanism 30, and meshed with the worm wheel 25. The worm 26 may be provided with a worm 26 and a worm shaft 27 serving as rotating means that is connected to the worm 26 and is exposed in a reachable state in a seated state.

In this embodiment, the cam mechanism 30 includes an end cam 31 and a driven cylinder 32 as a driven joint. A driven cylinder 32 is provided between the end cam 31 and the support plate 7. The end face cam 31 is rotatably fitted on the outer periphery of a cylindrical cam receiver 13 ′ formed on the front surface of the outer shell 2. And cam receiver 1
A hole 13a 'having a square cross section is formed at the center of 3', and a shaft section 14 'having a rectangular cross section of the driven cylinder 32 is inserted.

On one end surface of the driven cylinder 32, there is provided a cam contact surface 32a having an uneven surface opposite to the cam surface 31a of the end cam 31.
Are formed. The cam contact surface 32a comes into close contact with the cam surface 31a of the end cam 31 when the cam displacement is 0 when the cam contact surface 32a faces the cam surface 31a. Then, the cam displacement increases with the rotation of the end face cam 31, and a predetermined angle, for example, approximately 1
A cam surface 31a and a cam contact surface 32a are formed so as to obtain the maximum cam displacement when rotated by 80 degrees.

The end of the driven cylinder 32, which is in contact with the connecting portion 7b of the support plate 7 on the side opposite to the cam contact surface 32a,
As shown in FIG. 8, it protrudes in a conical shape. Further, inside the driven cylinder 32, a quadrangular prism-shaped shaft portion 14 'forming a gap / hole 32b with the inner peripheral surface is integrated. The shaft portion 14 'protrudes from the cam contact surface 32a and is slidably inserted into the hole 13a' of the cam receiver 13 '. That is, the shaft portion 14 'of the driven cylinder 32 is
3a 'and the cam receiver 13' is
Of the driven cylinder 3 by being inserted into the hole 32b inside the
2 is slidably supported in the axial direction without rotating with respect to the cam receiver 13 '.

The follower is not limited to a cylindrical one having an annular cam contact surface 32a, and a rod-like follower may be employed. End cam 31 and driven cylinder 32
May be reversed so that the end cam 31 side is moved in the axial direction so that the support plate 7 protrudes toward the waist. Further, as the cam mechanism 30, a swash plate cam may be employed in addition to the above-described end cam, and in some cases, an inverted cam may be employed. Furthermore, a stepwise cam as shown in FIG. 5 may be used.

The worm shaft 27 is axially fixed to the outer shell 2 "by a holding member (not shown) and rotatably mounted. One end of the worm shaft 27 is located at a lower portion of one side of the outer shell 2". It is protruding.
An operation knob 28 is fitted on the protruding worm shaft 27. The worm shaft 27 is installed so as to protrude out of the outer shell 2 ″ at a position away from the center line of the backrest, that is, at a position deviated from the center of the backrest. Since it is not located directly behind the back, the occupant can operate the worm shaft 27 without lifting the back from the backrest, and since the worm shaft 27 is exposed only on one side of the backrest, The occupant can operate the operating means using only one hand, thus improving the operability.However, the position of the worm shaft 27 is not particularly limited to the above-described position, and the occupant's hand may be in the seated state. It may be provided in a reachable range, or in a position where the user can operate after standing, depending on the case.Reference numeral 23 in Fig. 7 denotes a nail for connecting the outer shell 2 "and the inner shell 3". In addition, the support plate 7 of the present embodiment is the same as that of each of the above-described embodiments, and a description thereof will be omitted.The shape of the outer shell 2 ″ is not limited to the shape shown in FIG. Of course.

According to the lumbar support 6 of the backrest 1 ″ configured as described above, by rotating the operation knob 28, the worm 26 and the worm wheel 25 are rotated via the worm shaft 27, and the end cam 31 is rotated. As a result, the cam displacement of the cam mechanism 30 changes and the amount of protrusion of the support plate 7 changes, and the cam mechanism 30 is rotated by the worm 26 and the worm wheel 25, so that a load is applied to the support plate 7. Even if the driven cylinder 32 is pushed in, the end face cam 31 is not rotated, and the support plate 7 is not pushed back.

According to this embodiment, a part of the backrest 1 "can be easily protruded to the waist side by an arbitrary amount by rotating the operation knob 28. In addition, the operation knob 28 is provided outside the backrest 1". Is only exposed, so the backrest 1 "
Does not impair the appearance.

In the above-described embodiment, one worm shaft 27 exposed to the outside of the backrest 1 "is used as the rotating means. However, the present invention is not limited to this, and the rotating shaft of the worm 26 is rotated by a gear train. It may be a configuration.

In each of the above-described embodiments, the example in which the lumbar support 6 is applied to the backrest of the office swivel chair is described. However, the present invention is not particularly limited thereto. It may be applied to the backrest of other chairs. Further, the operating lever 17 and the worm shaft 27 as operating means may be arranged on the center line of the backrest.

[0067]

As is apparent from the above description, according to the lumbar support of the first aspect, the cam mechanism is driven by the operating means via the ratchet mechanism so that the backrest can swing on the shell member. The attached support plate is pushed forward by an arbitrary amount from the back side, so that the cushion of the backrest and a part of the upholstery can be pressed against the lumbar region of the seated person and supported. Moreover, since there is no exposed member other than the operation means around the backrest, the appearance is not impaired.

Further, since the operating means is arranged so as to be exposed within a reach of the user in a seated state, the protrusion amount of the support plate can be continuously adjusted with only one hand without changing the operating means in the seated state. be able to.

Further, since the cam mechanism is rotated via the ratchet mechanism and the operation lever, the operation is more complicated than the structure in which one operation lever, which is integrated with the cam and exposed to the outside, is directly rocked and rotated. The operation stroke of the means can be shortened. Therefore, the operability is improved, so that the seated person can easily adjust the protrusion amount of the support plate while sitting.

Further, since there is almost no change in the protrusion amount due to the temperature change, frequent fine adjustment for maintaining the protrusion amount constant is unnecessary. For this reason, usability can be improved. In addition, since there is almost no failure due to external factors, the life is long.

Further, in the lumbar support according to the second aspect, the cam mechanism comprises an end face cam and a follower having a cam contact surface which is disposed coaxially with and opposed to the end face cam, and has a reverse cam surface with the cam surface of the end cam. With this configuration, the movement by the cam operating mechanism can be converted into a reciprocating linear movement in the front-rear direction of the chair by a simple mechanism of the coaxial end face cam and the follower, so that the support plate can be protruded. Therefore, the structure of the lumbar support can be simplified.

Further, in the lumbar support according to the third aspect, the cam surface for guiding the follower when the cam displacement of the cam mechanism changes from the minimum to the maximum is increased as the cam displacement increases from the minimum to the maximum. Since the cam is changed so that the amount of change in cam displacement per rotation angle gradually becomes smaller, the amount of reaction force increase in one operation is kept constant, and the force to rotate the cam mechanism, that is, the feed mechanism is driven The operating force to be performed can be made constant. For this reason,
Operability can be improved.

Further, the lumbar support of claim 4 is
A support plate pivotally attached to the shell member of the backrest, a cam mechanism provided on the back side of the support plate for providing a displacement for projecting the support plate to the front side, and a worm wheel coaxially rotated with the cam mechanism And a worm meshed with the worm wheel, and a rotating means connected to the worm and arranged so as to be exposed in a reachable area in a seated state. By driving the cam mechanism,
The support plate is pushed forward by an arbitrary amount, and the cushion of the backrest and a part of the upholstery can be pressed against the waist of the seated person to support the waist. Moreover, since there is no exposed member other than the rotating means around the backrest, the appearance is not impaired.

Further, since the rotating means is arranged so as to be exposed within the reach of the user in a seated state, the protrusion amount of the support plate can be continuously adjusted with only one hand without changing the rotating means in the seated state. be able to.

Further, since the cam mechanism is rotated via the worm and the worm wheel, the rotation means is more complicated than a structure in which one operating lever integrated with the cam and directly exposed to the outside is rotated by directly swinging. Can be shortened. This improves operability,
The seated person can easily adjust the protrusion amount of the support plate while sitting.

Further, since the reverse rotation of the cam mechanism is prevented by the engagement of the worm and the worm wheel, there is no need to provide another reverse rotation preventing mechanism, and the structure of the lumbar support can be simplified.

Further, since there is almost no change in the protrusion amount due to the temperature change, frequent fine adjustment for maintaining the protrusion amount constant is not required. For this reason, usability can be improved. In addition, since there is almost no failure due to external factors, the life is long.

Further, in the lumbar support according to the fifth aspect, the cam mechanism comprises an end face cam and a follower having a cam contact surface having a cam contact surface which is disposed coaxially and opposed to the end face cam and has an opposite surface to that of the end face cam. Therefore, the support plate can be protruded by converting the motion of the cam operating mechanism into a reciprocating linear motion in the front-rear direction of the chair by a simple mechanism of the coaxial end face cam and the follower. Therefore, the structure of the lumbar support can be simplified.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a backrest of a chair provided with a lumbar support according to the present invention.

FIG. 2 is a longitudinal sectional view showing an embodiment of a backrest of a chair provided with a lumbar support.

FIG. 3 is an enlarged front view showing a lumbar support.

FIG. 4 is an exploded perspective view showing one embodiment of a cam mechanism.

FIG. 5 is a developed view showing a shape of a surface where the end cam and the driven cylinder face each other.

FIG. 6 is a front view showing another embodiment of the backrest of the chair provided with the lumbar support of the present invention.

FIG. 7 is a front view showing another embodiment of the backrest of the chair provided with the lumbar support of the present invention.

FIG. 8 is a longitudinal sectional view showing an embodiment of a backrest of a chair provided with a lumbar support.

FIG. 9 is an exploded perspective view showing one embodiment of a cam mechanism.

[Explanation of symbols]

 1, 1 ', 1 "backrest 3, 3" inner shell 6 lumbar support 7 support plate 8 cam mechanism 9 ratchet mechanism 10 end cam 10d area where no cam displacement is given 10e area where cam displacement is given 11 driven cylinder (follower joint) Reference Signs List 12 feed mechanism 16 detent pawl 17 operating lever (operating means) 20 feed pawl 25 worm wheel 26 worm 27 worm shaft (rotating means) 30 cam mechanism 31 end face cam 32 driven cylinder (follower)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masamitsu Miyashita 5331 Nishiharu Kinoshita Kawara, Ina-shi, Nagano Furniture Development Department, Takano Co., Ltd. (72) Inventor Tomokazu Murakami 6-1-1, Oimazato-minami, Higashi-Nari-ku, Osaka-shi, Osaka No. KOKUYO Co., Ltd. (72) Inventor Shigeo Iwamoto 6-1, 1-1 Oimazato-minami, Higashinari-ku, Osaka-shi, Osaka

Claims (5)

[Claims] 1. A lumbar support for projecting a part of a backrest of a chair toward an occupant's waist by an arbitrary amount,
A support plate swingably attached to the shell member of the backrest, and a displacement for rotating the support plate in one direction and projecting the support plate to the front side from the back side of the support plate, and at least a maximum cam displacement to a minimum cam displacement. A cam mechanism having a region where a cam displacement is given and a region where the cam displacement is not given alternately when rotating toward the camshaft, and a ratchet for rotating the cam mechanism in a single direction by a fixed amount. A lumbar support for a chair, comprising: a mechanism; and operating means for driving a feed claw of the ratchet mechanism, which is disposed within a reach of the user in a seated state. 2. The cam mechanism according to claim 1, wherein the cam mechanism includes an end cam and a follower having a cam contact surface which is disposed coaxially with and opposed to the end cam and has a cam contact surface with a concave / convex surface opposite to the cam surface of the end cam. A lumbar support for the chair according to item 1. 3. The cam surface when the cam displacement of the cam mechanism changes from a minimum to a maximum is such that the cam displacement per rotation angle of the cam mechanism gradually changes as the cam displacement changes from a minimum to a maximum. 3. The lumbar support of a chair according to claim 2, wherein the lumbar support has a curved surface shape that becomes smaller. 4. A lumbar support for projecting a part of a backrest of a chair toward an occupant's waist by an arbitrary amount,
A support plate swingably attached to the shell member of the backrest, a cam mechanism for applying a displacement for projecting the support plate to the front side from the back side of the support plate, and a worm coaxially rotated with the cam mechanism A lumbar support for a chair, comprising: a wheel; a worm meshed with the worm wheel; and a rotating means connected to the worm and arranged to be exposed in an accessible range in a seated state. . 5. The cam mechanism according to claim 1, wherein the cam mechanism comprises an end face cam and a follower having a cam contact surface which is arranged coaxially with and opposed to the end face cam and has a cam contact surface with a concave and a convex opposite to the cam surface of the end cam. A lumbar support for the chair according to item 4.