JP2003225136A - Chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in a chair having a conventional tilt mechanism that a large force is required to largely tilt a backrest backward, namely the backrest can be largely tilted backward only by not only applying the body weight but also using the muscles, or a petite person or light women cannot take a satisfactorily backward tilted stance. <P>SOLUTION: In this chair having a structure for compressing a coil spring in the backward titling of a backrest arm, the direction of compressing the coil spring is gradually changed relatively to the tangential direction of the rotation of the part receiving the action of the spring force on the backrest arm according to the backward tilting of the backrest arm. According to such a structure, since the coil spring is compressed to increase the total reaction of the coil spring according to the backward tilting of the backrest arm, while the direction of the total reaction of the coil spring is gradually shifted to the rotating direction of the backrest arm, the degree of compression of the coil spring and the shifting manner in the backward tilting of the backrest arm are set, whereby the magnitude of the effective component of the reaction of returning the backrest arm to a raised attitude of the coil spring can be properly controlled. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chair having a tilt mechanism capable of tilting a backrest.

[0002]

2. Description of the Related Art Conventionally, chairs having various backrest tilt mechanisms including a back seat synchro tilt and a tilt only on the back have been developed. In the case of a back seat synchro tilt, the base member is provided with a backrest arm rotatably supporting the base end portion, and in the case of the back seat synchro tilt, the base member is slidably and rotatably supported, and the rear end portion is supported. It has a seat rotatably supported near the base end of the backrest arm and a spring connected to the lower part of the seat so as to intervene between two points whose relative distance changes with tilting. In the case of tilting, the relative distance changes with tilting of the backrest at the lower part of the seat near the base end of the backrest arm or between the base end of the backrest arm and the backrest and at the lower rear part of the seat. Known to have a spring connected so as to intervene between two points To have. And these chairs are configured such that even when the backrest fixed to the backrest arm is tilted backward, the spring always applies the tilting force for tilting the backrest or the seat to the standing posture to return to the standing posture. Has been done.

[0003]

By the way, in a chair having such a tilt mechanism, normally, as the backrest is tilted backward, the force that the seated person has to apply to the backrest increases linearly, and If you want to lean backwards a lot, you need a lot of power.

When the back leaning amount of the backrest becomes large, the seated person leans the backrest backward by leaning the weight of the upper half of the body on the backrest. If you do not use, you may not be able to lean backward significantly, or if you are a small person or a woman with a light weight, you may not be able to take a leaning posture.

Further, even when the backrest is tilted to the maximum so that a small force is required, if the compression amount of the spring is set to be small or a spring having a small spring constant is used, the backrest will be in the vicinity of the standing posture. The initial tilting power of the spring when there is also becomes small, and the seated person just leans back a little,
There is a problem that it is unintentionally tilted backward.

Further, there is usually a mechanism for adjusting the tilting force of the spring, but this changes the initial force for tilting by changing the initial compression amount of the spring, thereby changing the apparent spring constant. However, the tilting power increases linearly with the back leaning.

[0007]

In order to solve the above problems, a chair according to the present invention is rotated relative to a base member which is attached to the upper part of a leg and has a seat portion on the upper side. A backrest arm that is movably arranged and includes one spring receiving portion; a spring force transmitting member that has one spring side connected to a base member and the other spring receiving portion that is on the other side beyond the backrest arm; and one spring. A chair having a coil spring arranged between a receiving portion and the other spring receiving portion, and configured to compress the coil spring when the backrest arm is tilted backward, wherein the backrest arm moves backward as the backrest arm tilts backward. The reaction force mechanism is characterized in that the direction in which the coil spring is compressed gradually changes relative to the tangential direction in which the portion on the leaning arm on which the spring force acts is about to rotate.

In such a case, as the backrest arm tilts backward, the coil spring is compressed and the total reaction force of the coil spring increases, but at the same time, the direction in which the backrest arm attempts to rotate. On the other hand, since the direction of the total reaction force of the coil spring gradually shifts, the magnitude of the effective component of the reaction force that causes the coil spring to return the backrest arm to the standing posture increases or decreases. By setting the degree of compression and the direction deviation of the coil spring when the backrest arm is tilted backward, it is possible to set various changes in the reaction force that causes the coil spring to return the backrest arm to the standing posture. The degree of freedom in designing the sitting comfort of the chair can be increased without changing the basic system for tilting the backrest.

This can be applied to a back seat synchro tilt mechanism in which the seat slides or rotates in conjunction with the back tilt of the backrest, or a back tilt mechanism in which the seat is fixed and only the backrest tilts backward. In addition, in order not to increase the reaction force when the backrest is greatly tilted backward with respect to the backrest initial reaction force when the backrest is in the vicinity of the standing posture, The force mechanism increases the angle between the tangential direction in which the action point that compresses the spring on the backrest arm is about to rotate and the direction in which the spring is compressed, as the backrest arm tilts backward from the most upright position. It is preferable that the value is changed as it goes. By doing this, the coil spring is compressed as the backrest is tilted backward, but the amount of the effective component of the reaction force that attempts to return the backrest arm to the standing posture depends on the degree of compression of the coil spring. Depending on the setting of the method of changing the angle formed by the tangential direction of the backrest arm and the direction of the spring, for example, when tilting the backrest backward, a straight line near the standing position is possible. It is also possible to increase the backrest reaction force and to moderate the increase in the backrest reaction force when further tilting backward from a position that is tilted backward to some extent.

Further, in order to realize this with a simpler structure, the reaction force mechanism is held so that the spring force transmission member cannot swing with respect to the base member, and as the backrest arm tilts backward. The horizontal position of one spring receiving portion may be moved relative to the spring force transmitting member and the other spring receiving portion.

With this configuration, the base member of the spring receiving portion on the spring force transmitting member is moved in the course of the horizontal position of the spring receiving portion on the backrest arm side moving due to the backrest tilting backward. Since the position of the backrest arm does not change, the angle formed by the tangential direction of the backrest arm and the direction of the spring can be easily changed.

In order to extend the life of the product by making the backrest arm, the coil spring, the spring receiving portion, etc., operate smoothly and avoid applying excessive force when the backrest is tilted backward. Is a separate member in which the spring receiving portion is arranged so that it can swing on the backrest arm and the spring force transmission member, and compresses the coil spring regardless of the rearward tilted state of the backrest arm. It is preferable that both spring receiving members face each other in the direction.

In order to make the system more compact, it is conceivable that the reaction force mechanism is arranged such that the spring force transmitting member penetrates the inside of the coil spring. By doing so, space can be effectively used and a compact design is possible. By doing so, when the backrest is tilted backward, the range in which the direction of the coil spring can change is limited to the range in which the spring force transmitting member fits within the inner diameter of the coil spring,
Even when an unexpected force such as an external force acts on the coil spring, it is possible to prevent troubles such as the coil spring coming off from the spring receiver.

Further, a seat portion that does not move in association with the backward tilting movement of the backrest arm, a backrest arm rotatably supported by a shaft below the base member, and the reaction force at the rear of the rotation axis of the backrest arm. By arranging the mechanism, it is possible to greatly improve the sitting comfort when tilting backward, while making the entire chair system a tilt mechanism only for the backrest while being simple and inexpensive.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

The chair according to this embodiment is shown in FIG.
As shown in the rear view in FIG. 2, a leg 1 including leg blades 11 having casters C and leg columns 12, a support body 4 supported by the leg 1 and having a seat 2 at an upper portion, and a rear side of the support body 4 The seat back 2 has a back tilting mechanism which does not move in conjunction with the backrest 3 when the backrest 3 is tilted backward.

A specific structure and component structure will be described with reference to FIGS.

That is, this chair has a seat 2 and a backrest 3
A gas spring receiver 41 having a base member 21 at its upper portion is attached to an upper portion of a gas spring GS arranged inside the leg column 12 to raise and lower the whole body, and a portion near a front end portion of a backrest arm 31 is provided with the gas spring GS. Receiving 4
A backrest arm rotating shaft 32 is rotatably attached to the unit 1. Further, the backrest arm 31 is arranged such that its front portion is located below the base member 21.
The backrest 3 is bent rearward from the rear end portion and holds the backrest 3 at the upper portion thereof. The backrest arm 31 has a spring compression point 33 at a position corresponding to the lower portion near the rear end portion of the base member 21. The spring receiving bracket 34 having the spring compression action point 33 is integrally attached so that it comes to the left.

The spring compression acting point 33 forms a left and right rotary bearing of the chair, and the upper spring receiving member 5 is provided there.
1 is mounted so that it can be swung in the front-back direction of the chair, and the spring receiving surface faces downward. Further, an elongated hole in the front-rear direction is provided on the upper surface of the upper spring receiving member 51 so as to be movable in the front-rear direction while penetrating the spring force transmitting member 53.

Next, the coil spring SP is arranged so as to be sandwiched between the spring receiving surface of the upper spring receiving member 51 and the spring receiving surface of the lower spring receiving member 52, near the rear end of the base member 21 and at the lower end thereof. Spring force transmitting member 53 having a screw
Downward, upper spring receiving member 51, coil spring S
P, so as to penetrate the lower spring receiving member 52, and be attached to the base member 21 so that neither swinging nor rotation is possible, and the operation portion SS is screwed and fixed to the lower end portion of the spring force transmitting member 53. The initial compression amount of the coil spring SP is changed by adjusting the amount of screwing of the operation portion SS to adjust the overall reaction force of the backrest 3. Here, the lower spring receiving member 52
Is operating portion SS while penetrating the spring force transmitting member 53.
So that it can be swung inward, the recessed portion 522 at the center of the bottom surface and the tip end R portion 54 of the swinging member 54 arranged on the operation portion SS.
2 is involved, and there is a spring force transmitting member through hole 521 at the center of the recess.

The main parts of the tilt mechanism will be described in detail with reference to FIG. 5. The upper part of the gas spring GS, which is taper-fitted in the central hole of the leg blade 11, is formed by bending and welding a steel plate. The gas spring receiver 41 is taper-fitted. The gas spring receiver 41 is welded so that the four positioning protrusions 412 provided on the gas spring receiver 41 are fitted into the four positioning holes 211 of the base member 21 to be integrated. I am doing it.

The backrest arm 31 is formed by arranging two round pipes bent in a substantially L shape in parallel with each other, and a backrest mounting bracket 35 is welded near the upper end so as to straddle the two round pipes, and an intermediate portion is formed. A spring receiving bracket 34 is welded so as to straddle two round pipes.
The left and right outer sides of the gas spring receiver 41 are arranged so that the backrest arm rotation shaft mounting holes 311 provided near the lower tip end portion thereof are adjacent to the positions of the backrest arm rotation shaft mounting holes 413 provided in the gas spring receiver 41. , The backrest arm rotation shaft 32 is attached so as to pass through the attachment holes 311 and 413 of the two members, and both ends thereof are attached with E rings or the like.
I'm stopping it from falling out. With this configuration, the backrest arm 31 is rotatable about the backrest arm rotation shaft 32 with respect to the gas spring receiver 41 and the base member 21, and the steel plate is bent upward at the rear portion of the gas spring receiver 41. Can be tilted backward until it hits the rearward stopper 414.

The spring receiving bracket 34 is formed by bending four sides of a steel plate, and is provided with a semicircular notch at substantially the center of the left and right sides bent downward, and a not-shown resin bearing member is fitted therein. Is. This is the spring compression action point 33 that receives a reaction force that rotates the backrest arm 31 to the standing posture from the coil spring SP. A circular opening is provided at the center of the spring receiving bracket 34 to avoid interference with an upper spring receiving member 51, which will be described later. The backrest arm 31 secures the strength and rigidity necessary to hold the backrest 3 by integrating the two substantially L-shaped round pipes, the backrest mounting bracket 35, and the spring receiving bracket 34. .

The upper spring receiving member 51 is formed by drawing a steel plate into a substantially circular dish shape having a downwardly facing wall surface around the upper surface thereof.
P can be held stably. In addition, a spring bearing swing shaft 512 having upward cylindrical surfaces on both left and right sides of the wall surface.
Are simultaneously formed at the time of drawing the upper spring receiving member 51. In the upper spring receiving member 51, a spring force transmitting member 53, which will be described later, penetrates the central portion of the upper spring receiving member in the vertical direction. Therefore, the spring receiving swing shaft 512 cannot be a single continuous shaft, and the central portion thereof is not formed. It is necessary to divide the left and right of the axis with
Since the strength that can receive the reaction force of the coil spring SP is required, the integral drawing is performed in this way.
Further, on this upper surface, a spring force transmitting member penetrating elongated hole 51 for penetrating the spring force transmitting member 53, which is oriented in the chair front-rear direction,
1 is formed, and a brim portion having a mechanical portion cover mounting hole 513 is formed in the lower rear portion of the cylindrical surface. The upper spring receiving member 51 includes the spring receiving swing shaft 512,
The backrest arm 31 is rotatably arranged at a spring compression point 33.

The lower spring receiving member 52 is formed by drawing a steel plate into a substantially circular dish shape having an upward wall surface around the bottom surface thereof.
P can be held stably. A lateral semi-cylindrical recess 522 having an upwardly projecting bottom surface is formed so as to be pivotable with respect to the spring force transmitting member 53 via a swinging member 54 to be described later. A spring force transmitting member through hole 521 for penetrating the spring force transmitting member 53 is formed in the portion. Coil spring SP
Are arranged so as to be sandwiched between the upper spring receiving member 51 and the lower spring receiving member 52.

The mechanical portion cover MC has a substantially U-shape that is open upward and has a lower surface, and has a circular hole on the lower surface that is large enough to allow the coil spring SP to pass through, and extends downward from the outer peripheral portion of the circular hole. A cylindrical side wall having no bottom surface. In addition, in the rear part of the circular hole on the lower surface of the substantially U-shaped,
There is a mounting hole MC1 corresponding to the mechanical unit cover mounting hole 513 of the upper spring receiving member 51.

The swinging member 54 is a lower spring receiving member 52.
Is for holding the coil spring SP so as to be swingable and rotatable with respect to the spring force transmission member 53 by compressing the coil spring SP by screwing in an operation portion SS which will be described later, and the tip end R portion of the steel plate bent upward at an acute angle. A spring force transmitting member through hole 541 is provided at the center of 542, and a thick cylindrical portion is provided below the through hole 541. The swinging member 54 is arranged such that the tip end R portion 542 contacts the recess 522 of the lower spring receiving member 52 from the lower surface side and forms a virtual swing axis line 55 of the lower spring receiving member 52 there. It

The operating portion SS has a substantially disk-shaped outer shape, and is formed with a female screw which is screwed into the tip screw portion 532 of the spring force transmitting member 53 in the thickness direction of the central portion. The spring force transmitting member 53 has a square column-shaped rotation stopper 5 on the lower surface of the hemispherical upper end.
31, a cylindrical shaft portion extends downward from the central portion of the lower surface, and a tip screw portion 532 that is a screw is formed near the lower end portion of the shaft portion. On the other hand, the base member 21
The spring force transmitting member mounting hole 212 near the rear end portion has a circular hole in the center of the bottom surface of the rectangular columnar concave portion, so that the rotation stopping portion 531 of the spring force transmitting member 53 can be fitted therein and the operation described later can be performed. When the portion SS is screwed in, it can be held so as not to rotate integrally, and by having a cylindrical shape that extends downward on the lower surface side around the circular hole, swinging of the spring force transmission member 53 can be prevented. It is like this.

The spring force transmitting member 53 is penetrated from above into the spring force transmitting member mounting hole 212 of the base member 21,
The spring force transmitting member 53 is arranged so as not to rotate, and at the same time, the spring force transmitting member 53 has a spring force transmitting member penetrating hole 511 of the upper spring receiving member 51, a coil spring SP, and a spring force transmitting member penetrating hole 521 of the lower spring receiving member 52 from below. All the members penetrated by the spring force transmitting member 53 are fixed by penetrating the spring force transmitting member through hole 541 of the swinging member 54 and screwing the operation portion SS into the tip screw portion 532. Further, by adjusting the screwing amount of the operation portion SS, the initial compression amount of the coil spring SP is changed, and the general reaction force of the backrest 3 is adjusted.

In the mechanical portion cover MC, a substantially U-shaped portion that opens upward covers a part of the arm 31 on the back and covers the left and right sides thereof, and a cylindrical portion that extends below the substantially U-shaped portion is formed. The upper spring receiving member 51, the coil spring SP, and the lower spring receiving member 52 are arranged from below so as to cover the side surfaces of the mechanical spring cover MC, and the mounting holes MC1 of the mechanical cover MC are inserted into the upper spring receiving member 51.
The position is aligned with the mechanical unit cover mounting hole 513 and screwed here. Here, when the backrest arm 31 is in the most upright position, the operation portion SS is exposed downward from the cylindrical portion under the mechanical portion cover MC and can be operated.

The operation of the above configuration will be specifically described below.

FIG. 3 shows the posture in which the backrest 3 is in the most upright position. At this time, the spring compression action point 33 is at a substantially rearward position with respect to the backrest arm rotation shaft 32 and the lower spring receiving member 52 is provided. It is directly above the center of the swing axis 55 of the.
Further, the coil spring SP is in a compressed state at least to generate a spring reaction force capable of holding the backrest arm 31 in the standing position. At this time, the coil spring SP passes through the direction of the spring force, that is, the center of the coil spring SP. The vertical direction is a tangential direction in which the spring compression action point 33 tries to rotate by the reaction force of the coil spring SP, that is, a straight line connecting the axial center of the backrest arm rotation shaft 32 and the spring compression action point 33. On the other hand, the spring compression action point 33 is oriented in a vertically upward direction from the starting point, and these two directions are substantially coincident with each other.
Therefore, in the vicinity of the backrest upright posture, the coil spring S
Almost all of P's reaction force is a force to return the backrest 3 to the standing posture. However, the coil spring S at this time
Since the compression amount of P is small, the reaction force is small.

When the backrest arm 31 is tilted rearward from here, the spring compression point 33 rotates forward and downward about the backrest arm rotation shaft 32, but the lower spring receiving member 52 is rotated. As described above, the swing axis 55 has a structure that does not move along with the back tilting of the backrest. Further, the tangential direction in which the spring compression action point 33 tries to rotate due to the reaction force of the coil spring SP is inclined toward the rear of the chair, so that the spring compression action point 33 with respect to the direction of the reaction force of the coil spring SP. The rotational tangential direction of is shifted.

FIG. 4 shows a posture in which the backrest 3 is largely tilted backward, and at this time, the spring compression action point 33 is located at a substantially rear rear position with respect to the backrest arm rotation shaft 32 and the lower spring support. It is above and in front of the swing axis 55 of the member 52. At this time, the direction of the spring force, that is, the vertical direction passing through the center of the coil spring SP, is the tangential direction in which the spring compression action point 33 tries to rotate by the reaction force of the coil spring SP, that is, the backrest arm rotation. A straight line connecting the axis of the shaft 32 and the spring compression action point 33 is oriented vertically upward from the spring compression action point 33 as a starting point, and these two directions are largely deviated from each other.

Therefore, the backrest arm 31 responds to the total reaction force F1 of the coil spring SP, which is largely compressed at this time.
The reaction force component Fy acting in the direction to return the to the standing posture becomes small. The magnitude and direction of the total reaction force F1 of the coil spring SP and the force components Fx and Fy acting on the spring compression point 33 are conceptually represented.

Further, when the reaction force Fy is tilted backward from the standing posture, the magnitude of the reaction force Fy is increased, but the increase rate is gradually reduced, and the increase rate becomes zero. Here, the reaction force Fy is the maximum value, and when it is further tilted backward from here, the reaction force Fy turns to a direction in which it decreases, and the backrest arm rotating shaft 32 and the spring compression action point 3
3. When the swing axis 55 of the lower spring receiving member is aligned, the reaction force Fy becomes zero again. When tilted further backward than this, the backrest arm 31 does not return to the standing posture.

The rearward tilt of the backrest arm 31 is at least
It is necessary to stop before the reaction force Fy becomes zero again. Practically, it is preferable to stop the rearward leaning of the backrest arm 31 at an appropriate point between the maximum value of the reaction force Fy and zero again. In some cases, it is also preferable to stop the tilting of the backrest arm 31 before the reaction force Fy reaches the maximum value. In the present embodiment, the rearward inclination is stopped by using the rearward inclination stopper 414. Further, although the coil spring SP inclines toward the front of the chair as the backrest arm 31 tilts backward, the mechanical cover MC does not move to the upper spring receiving member 51.
Is fixed to the upper spring receiving member 51, the coil spring SP, and the lower spring receiving member 52.
The size can cover only the substantial outer shape of, and a compact design can be achieved. As is clear from the above description, if the positional relationship among the backrest arm rotation shaft 32, the spring compression point 33, and the swing axis 55 of the lower spring receiving member is changed, the backrest arm 31 tilts backward. In the process, the coil spring SP can set various changes in the reaction force to return the backrest arm 31 to the standing posture.

When the backrest is in the most upright position, the spring compression point 33 is applied to the axial center position of the backrest arm rotation shaft 32.
Is below the same height on the rear side of the chair, and the spring compression point 3
It is clear from the above description that if the swing axis line 55 of the lower spring receiving member 52 is located directly below 3, it is possible to prevent the reaction force from increasing too much when the backrest is greatly tilted backward. For example, if the initial position of the spring compression action point 33 is set to the rear of the position just above the swing axis line 55 of the lower spring receiving member 52, the spring compression action point 33 will be in the process of tilting the backrest arm 31 backward. Since the coil spring SP is compressed while the coil spring SP is rotating right above the swing axis 55 of the lower spring receiving member 52, the coil spring SP also coincides with the direction in which the backrest arm 31 is effectively rotated. The backrest reaction force suddenly becomes stronger, but beyond this point, the increase in the backrest reaction force becomes moderate.

In these, the swing axis 55 of the lower spring receiving member 52 is the spring force transmitting member mounting hole 212 of the base member 21.
By contrast, by being connected so that it cannot swing,
Although it is realized by a simple structure, if it is desired to make the degree of change of the backrest reaction force more remarkable, the position of the swing axis line 55 of the lower spring receiving member 52 can be increased in the process of the backrest arm 31 tilting backward. It may be possible to move the chair toward the back of the chair rather than fixing it. For example, the spring force transmitting member 53 may be connected to the base member 21 so as to rotate counterclockwise in FIG. 5 as the backrest arm 31 tilts backward. As an example, the backrest arm rotation shaft 32 is integrally rotated with the backrest arm 31, and a gear is integrally provided at the center of the backrest arm rotation shaft 32 in the longitudinal direction. A gear having an axis of rotation in the left-right direction of the chair is integrally provided on the upper end of the force transmission member 53, and the gear is rotatably attached near the rear end of the base member 21 so that the rotational force can be transmitted between the two gears. Thus, several gears are arranged on the base member 21.

Alternatively, a portion slightly below the upper end of the spring force transmitting member 53 is rotatably attached to the vicinity of the rear end of the base member 21 in the front-rear direction of the chair, and the backrest arm 31 is in the standing position, and the backrest arm rotation shaft 32 is provided. The backrest arm 31 has a crank shape in which the center portion in the longitudinal direction of the
And the spring force transmitting member 53.
It is conceivable to rotate the backrest arm 31 and the spring force transmission member 53 in an interlocking manner by connecting the upper end of the backrest arm and the crank portion of the backrest arm rotation shaft 32 with a linear link member.

A coil spring SP connecting the spring compression point 33 and the swing axis 55 of the lower spring receiving member 52.
If the design is such that there is a small deviation between the direction of the reaction force of and the direction in which the spring compression action point 33 tries to rotate around the backrest arm rotation shaft 32, the backrest arm 31 and the spring force transmission member 53.
However, in order to increase the deviation in the direction, it is necessary for the upper and lower spring receiving members 51 and 52 to shake their heads to follow the coil spring SP whose direction changes. By doing so, it is possible to prevent the coil spring SP itself from being bent or to apply a force in an extra direction to the upper and lower spring receiving members 51 and 52, which leads to smooth operation and extension of product life.

The spring force transmitting member 53 includes the spring force transmitting member penetrating elongated hole 511 of the upper spring receiving member 51, the coil spring SP, the spring force transmitting member penetrating hole 521 of the lower spring receiving member 52, and the swinging member 54. Spring force transmitting member through hole 5
41 and the operation portion SS are arranged so as to penetrate, and thereby a compact system is achieved by effective use of space, and even when an unexpected force is applied, the upper / lower spring bearing members 51/52 are used to coil the coil. It has a structure that can prevent troubles such as the spring SP coming off. However, when the backrest arm 31 is tilted backward, the range in which the direction of the coil spring SP can change is limited to the range in which the spring force transmission member 53 fits within the inner diameter of the coil spring SP. The spring compression point 33
And the direction of the reaction force of the coil spring SP that connects the swing axis 55 of the lower spring receiving member 52 and the direction in which the spring compression point 33 tries to rotate around the backrest arm rotation shaft 32 are designed to be large. If you do, there is a disadvantage.

At this time, it is conceivable that the spring force transmitting member is arranged on the left and right outside of the coil spring SP, and the lower spring receiving member 52 is held at the lower end thereof. By doing so, it is possible to prevent interference between the spring force transmitting member and the coil spring SP when the backrest arm 31 is tilted rearward, and it is possible to design a large deviation in the above direction.

Further, when the interlocking mechanism of the base member 21 and the seat 2 and the backrest arm 31 is not installed, the base member 21 and the seat 2 do not move in association with the backward tilting motion of the backrest arm 31, and By arranging the reaction force mechanism 5 behind the backrest arm rotation shaft 32, the entire chair system can be used as a backrest-only tilt mechanism, which is simple and inexpensive, and greatly improves the sitting comfort when tilted backward. However, the present invention is not limited to this, and can be applied to a back seat synchro tilt mechanism in which the motion of the back seat is interlocked, or the reaction force mechanism 5 can be arranged in front of the seat.

Hereinafter, description will be made with reference to FIG. here,
Members corresponding to FIGS. 1 to 5 have the same name,
It is marked.

The backrest arm 31 is rotatably held by the backrest arm rotation shaft 32 at the top portion bent downward by approximately 90 degrees on the rear upper surface side of the base member 21. The backrest arm 31 is divided into left and right portions in the vicinity of the front end portion that extends forward, and the upper spring receiving member 51 is rotatably held by the upper spring receiving member swing shaft 512 between them. The coil spring SP is arranged on this, and the lower spring receiving member 52 is arranged on it.

The spring force transmitting member 53 is the lower spring receiving member 5
2. The coil spring SP, the upper spring receiving member 51, and the base member 21 are penetrated so as not to rotate and swing with respect to the base member 21, and the lower spring receiving member 52 is provided near the upper end portion. It is held so that it can be swung by a swing axis 55, and is operated below the base member 21 by the operation portion SS.
The initial compression amount of the coil spring SP can be adjusted by screwing.

In the case of this structure, when the backrest arm 31 is tilted rearward about the backrest arm rotation shaft 32, the front end portion of the backrest arm 31 pushes the upper spring receiving member 51 upward to transmit the spring force. The coil spring SP is compressed between the coil spring SP and the lower spring receiving member 52 held at the upper end of the member 53.

Also in this structure, when the backrest arm 31 is tilted backward, the rotational tangent direction of the spring compression action point 33 deviates from the direction of the reaction force of the coil spring SP, and the desired effect of the present invention is obtained. To be

FIG. 7 is an operation conceptual diagram showing an example in which this reaction force mechanism is applied to the back seat synchro tilt system.

The reaction mechanism 5 shown here is the same as that shown in FIGS.
Basically, the spring force transmission member 53 is arranged on both left and right sides of the coil spring SP without penetrating the coil spring SP. With this configuration, the range in which the direction of the coil spring can change when the backrest is tilted backward is not limited to the range in which the spring force transmitting member fits within the inner diameter of the coil spring. Further, the back seat synchronizing mechanism has a front end slidably attached to the base member 21 above the base member 21, and a front end of the backrest arm 31 extended upward at a right angle from the backrest arm rotation shaft portion. This is a general structure in which the rear portion of the base member 21 is rotatably connected to the portion so as to interlock with the rearward inclination of the backrest arm 31. It can be realized by simply connecting the seat to the reaction mechanism of the present invention so as to interlock with each other, and it is understood that the effects of the present invention can be obtained in this case as well.

The present invention can be modified in various ways other than those shown above.

[0053]

According to the chair of the present invention described in detail above, as the backrest arm tilts backward and the coil spring is compressed, all the coil springs are rotated in the direction in which the backrest arm is about to rotate. Since the direction of the reaction force gradually shifts, the degree of freedom in designing the sitting comfort of the chair can be increased without changing the basic system for tilting the backrest.

[Brief description of drawings]

FIG. 1 is a diagram showing a main exterior side surface of a chair according to the invention of this application.

FIG. 2 is a view showing the main exterior rear surface of a chair according to the invention of this application.

FIG. 3 is a layout view of main components when the backrest of the chair according to the invention of this application is in a standing posture.

FIG. 4 is a layout view of main components when the backrest of the chair according to the invention of this application is in a backward tilted posture.

FIG. 5 is a configuration diagram of main parts of a chair according to the invention of this application.

FIG. 6 is a view showing an embodiment in which the reaction force mechanism of the chair according to the invention of this application is in the front portion of the seat.

FIG. 7 is a view showing an example in which the reaction force mechanism of the chair according to the invention of this application is applied to a back seat synchro tilt system.

[Explanation of symbols]

1 leg 11 leg feathers 12-leg support C caster GS gas spring Two seats 21 Base member 211 Positioning hole 212 Spring force transmission member mounting hole 3 backrest 31 backrest arm 311 Backrest arm rotation shaft mounting hole 32 Backrest rotation axis 33 Spring compression point 34 Spring bracket 341 Spring receiving interference prevention hole 35 Backrest mounting bracket 4 support 41 Gas spring receiver 411 Gas spring fitting hole 412 Positioning protrusion 413 Backrest arm rotation shaft mounting hole 414 Rear tilt stopper 5 Reaction mechanism 51 Upper spring receiving member 511 Spring hole for transmitting a spring force transmitting member 512 Spring bearing swing axis 52 Lower spring receiving member 521 Spring force transmitting member through hole 522 depression 53 Spring force transmission member 531 Rotation stop 532 Tip screw part 54 Pivoting member 541 Spring force transmitting member through hole 542 Tip R part 55 Swing axis of lower spring receiving member SP coil spring MC mechanism cover SS operation section MC1 mounting hole

Claims (6)

[Claims] 1. A backrest arm including a base member attached to an upper portion of a leg and having a seat portion on an upper side, and a spring receiving portion arranged so as to be rotatable relative to the base member. A spring force transmission member having one end connected to the base member and the other spring receiving part on the other end that exceeds the backrest arm, and a coil arranged between one spring receiving part and the other spring receiving part. A chair having a spring, which is configured to compress a coil spring when the backrest arm is tilted backwards. As the backrest arm tilts backwards, the portion on the backrest arm where spring force acts rotates. A chair having a reaction force mechanism in which a direction for compressing a coil spring gradually changes relative to a tangential direction to be attempted. 2. The angle formed by the tangential direction in which the point of action of compressing the spring on the backrest arm of the reaction mechanism is about to rotate and the direction in which the spring is compressed is determined from the posture in which the backrest arm is in the most upright position. The chair according to claim 1, wherein the chair is changed so that it becomes larger as it leans. 3. The spring force transmitting member of the reaction force mechanism is held so as to be unable to swing with respect to the base member, and the horizontal position of one spring receiving portion is the spring force transmitting member as the backrest arm tilts backward. And one that moves relative to the other spring receiving portion.
The chair described in. 4. The spring receiving portion of the reaction mechanism is a separate member that is swingably arranged on the backrest arm and the spring force transmitting member, and compresses the coil spring regardless of the rearward tilting state of the backrest arm. The chair according to any one of claims 1 to 3, characterized in that both spring receiving members face each other in the direction in which the spring receiving member faces. 5. The chair according to claim 1, wherein the spring force transmission member of the reaction mechanism is arranged so as to penetrate the inside of the coil spring. 6. A seat portion that does not move in association with the back tilting movement of the backrest arm, a backrest arm that is rotatably pivoted below the base member, and the reaction force behind the rotation axis of the backrest arm. The chair according to any one of claims 1 to 5, wherein a mechanism is arranged.