JP2002142897A - Backrest tilt range adjustment device for chair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tilting range adjusting device for a backrest in a chair, wherein the structure can be simplified, the size and weight can be reduced, and the manufacturing cost can be reduced. A back rod extending forward from a lower end of a backrest.
Is pivotally supported on a support base 4 for supporting the seat with a shaft extending in the left-right direction, and an arm 38 that rotates integrally with the back rod 6 is provided in the support base 4. Regulating members 42, 44 for regulating the rotation range of the distal end portion are provided so that they can be moved laterally by operating the operating levers 60, 61 disposed below the seat.
4, the arm 38 is moved to one side.
The amount of protrusion of the tip of the arm into the rotation locus gradually increases, and the arm 3
8 is a wedge-shaped contact portion 4 which has a small rotation range.
9 and 66 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chair in which a backrest can be tilted rearward and downward against a spring so that the tiltable range of the backrest can be adjusted.

[0002]

2. Description of the Related Art There have been proposed various chairs in which a backrest can be tilted rearward and downward against a spring. However, the conventional chair has a substantially vertical standing position and a rearward and downward position. It is designed to be able to tilt between the maximum tilt position and the maximum rear tilt position. Since the tiltable range of the backrest cannot be adjusted, the usability is poor.

The inventors of the present invention have solved this problem and have developed a device capable of freely adjusting the tiltable range of the backrest.
No. 318834 (filed on November 9, 1999).

[0004]

However, the prior invention described above converts the rotational movement of the back rod (backrest rod) into a linear movement in the front-rear direction of the tilt range adjusting member, thereby restricting this range of movement. So that the means of linking them was complicated,
There remains a problem that the entire device becomes large.

The present invention has solved such a problem, that is, an apparatus for adjusting the tilting range of a backrest in a chair, which has a simpler structure, can be reduced in size and weight, and has been improved so as to reduce the manufacturing cost. It is intended to be.

[0006]

According to the present invention, the above-mentioned problem is solved as follows. (1) The front end of the back rod extending forward from the lower end of the backrest is pivotally supported on a support base for supporting the seat with an axis extending in the left-right direction, and is integrally formed with the back rod in the support base. A rotating member is provided, and a regulating member that regulates a rotating range of a tip portion of the arm is provided so as to be laterally movable by operating an operation lever disposed below the seat, and By being moved to one side by the regulating member,
A generally wedge-shaped contact portion is provided so that the amount of protrusion of the tip of the arm into the rotation locus gradually increases to reduce the rotation range of the arm.

(2) In the above item (1), a shaft extending in the left-right direction is protruded from the distal end of the arm, and this shaft comes into contact with a contact portion of a regulating member which moves in the front-rear direction. To

(3) In the above item (1) or (2), the abutting portion of the regulating member is stepped, and the rotation range of the backrest is regulated stepwise.

(4) In the above item (3), the regulating member is
An elastic pressure holding means for stably stopping at a plurality of stop positions corresponding to each step of the step-shaped contact portion is provided.

(5) In the above item (4), when the elastic pressure holding means comprises an elastically deformable projection provided on a sliding portion of the regulating member with the support base, and when the regulating member stops at a plurality of stop positions, It is assumed that the projection comprises a plurality of recesses provided on the support base so as to elastically engage with each other.

(6) In any one of the above items (1) to (5), a pair of left and right cylinder shafts is rotatably disposed in a cylinder facing left and right provided on both side walls of the support base. The outer ends of both cylinder shafts are fixed to the front ends of a pair of left and right back rods, and the inner ends are
The base ends of a pair of left and right arms pointing in the same direction are fixedly fitted, and a shaft pointing in the left / right direction is penetrated at the distal ends of both arms, and the movement of the shaft is regulated by a regulating member.

(7) In the above item (6), a torsion bar pointing in the left-right direction is inserted into the left and right cylinder shafts, and both ends thereof are fixed to the left and right back rods, respectively. Between the inner ends, the base end of the adjustment plate is fixed to the center of the torsion bar, and the angle of the end of the adjustment plate is set in a space sandwiched between a pair of left and right arms and the shaft of the end. Angle adjusting means for adjusting the angle is provided.

[0013]

An embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, casters (2) are provided at the distal ends of the support legs (1) extending radially from the center, and the center of the support legs (1) is A pillar (3) is erected, and a support (4) is fixed to the upper end of the pillar (3).

A pair of right and left back rods (6) supporting the backrest (5) are formed on the support base (4) so as to extend rearward and upward in an L shape in a side view.
The front end of the lower part facing forward is pivotally mounted so as to be rotatable around an axis pointing in the left-right direction, and the backrest (5) and the back rod (6) are provided in the support base (4) and will be described later. The elastic reclining mechanism (7) and the tilt range adjusting device (8) allow the tilting range adjusting device (8) to tilt backward from the standing position as shown in FIG. 1 within the range defined by the tilt range adjusting device (8). Has become.

Above the support (4), a seat (9) is provided with a seat (1).
0), the backrest (5) and the back bar (6) are supported so as to move rearward and downward in conjunction with the backward tilt of the backrest. Since the support structure of the seat (9) and its linking mechanism with the backrest are not directly related to the present invention, a detailed description thereof will be omitted.

Armrests (12) are provided on both sides of the seat receiver (10) via support rods (11) extending in the left-right direction.

Next, the details of the elastic reclining mechanism (7) and the tilt range adjusting device (8) provided in the support (4) will be described with reference to FIGS.

The supporting base (4) has a box shape whose lower surface is open,
The rear part is fitted on the upper end of the pillar (3) and is supported on the pillar (3) so as to be slightly inclined forward and upward.

At the front and rear portions of both side walls (4a) of the support base (4), a tapered cylindrical body (13) whose diameter is slightly reduced outward.
(14) is formed integrally.

A pair of left and right cylindrical shafts (16) each forming a hexagonal cylindrical shape is provided in a through hole (15) penetrating through each rear cylindrical body (14) and the side wall (4a) of the support base (4). It is rotatably supported by a pair of inner and outer bushes (17, 18). The outer ends of the left and right cylindrical shafts (16) projecting outward from the cylindrical body (14) are connected to the inner end surface of a laterally truncated cone-shaped receiver (19) formed at the front end of the back rod (6). It is fitted into the formed hexagonal hole (20) and is fastened by a set screw (21).

The inner ends of the left and right cylindrical shafts (16) are separated from each other. A series of elongated torsion bars (22) consisting of multiple leaf springs stacked and bundled in the left and right cylinder shafts (16)
Are loosely fitted, and both ends of the torsion bar (22) are
The receiver (19) of (6) is press-fitted into a rectangular hole (23) formed at the deep end of the hexagonal hole (20) and fastened by a set screw (not shown) as necessary.

In the gap between the inner ends of the left and right cylinder shafts (16), a front-facing adjusting plate (24) having a central portion of a torsion bar (22) inserted into a square hole (24) formed in the base end portion. 25) is provided.

A cylindrical portion (27) having a screw hole (26) oriented substantially vertically is fixed to the tip of the adjusting plate (25) facing forward.

The screw hole (26) has a rotating handle (2
An adjusting screw (29) having an upper end (8) is screwed into the upper wall (4b), and an upper end protruding upward from the screw hole (26) is brought into contact with a lower surface of the upper wall (4b) of the support base (4). By adjusting the distance from the torsion bar (22) to the tip of the adjustment plate (25), the amount of initial torsion of the torsion bar (22) when the backrest (5) is located in the upright position is adjusted. ), The biasing force for returning to the standing position can be adjusted.

An angle adjusting means for adjusting the angular position of the adjusting plate (25) about the center axis of the torsion bar (22) is formed by the screw hole (26) and the adjusting screw (29).

The angle adjusting means and the torsion bar
(22), the cylinder shaft (16), the cylinder (14) and the like form an elastic reclining mechanism (7).

A round hole (30) and a U-shaped notch (31) are provided at a point symmetrical position about the square hole (24) in the adjusting plate (25).

On both sides of the base of the adjustment plate (25), there is an insertion hole (32) in the center where a torsion bar (22) passes, and on the outer surface, the inner end of the cylindrical shaft (16) rotates. A pair of synthetic resin bearings (3) having a circular recess (33) that fits freely
4), the boss (35) protruding from each inner surface, the adjustment plate (25)
Bearing that fits into the round hole (30) and notch (31)
By fitting a projecting shaft (36) projecting from the inner surface of (34) into an engaging hole (37) drilled in the center of the boss (35), the adjusting plate (25)
Are provided so as not to be able to rotate relative to.

The recess (3) of the bearing (34) in the left and right cylindrical shafts (16)
A hexagonal hole (39) provided at the base end (rear end) of a pair of left and right arms (38) facing forward is fitted outside the inner end fitted in 3). A shaft (40) that faces in the left-right direction is penetrated through both ends of the arms (38) so as to protrude to both sides.

As shown in FIGS. 3 to 9, on the right side of both arms (38) in the support base (4), there are main parts of the maximum back-tilt angle adjusting means (41) of the backrest (5). A certain first regulating member (42)
Similarly, on the left side, a second regulating member (44), which is a main component of the angle adjusting means (43) for the upright position (initial position) of the backrest (5), is attached to the upper wall of the support base (4). (4b) and a bottom plate screwed to the lower end of a pair of front and rear bosses (45) hanging from the lower surface
(46) sandwiched from above and below, and each regulating member (42) (44)
A front-rear guide groove (48) formed on the lower surface of the upper wall (4b) of the support base (4) with a front-rear groove (47) formed at the upper end of the base (4).
Are arranged so as to be slidably engaged with each other.

By moving the inner surface of the first regulating member (42) forward, the amount of protrusion of the right end of the shaft (40) into the vertical rotation trajectory gradually increases. (40) and arm
A substantially wedge-shaped contact portion (49) is formed so as to reduce the upward rotation range of (38).

In this example, the contact portion (49) which is inclined forward and upward.
Is formed in a stepped shape, and the receiving surface (50) of the shaft (40) in each step is formed in an arc shape close to the outer diameter of the shaft (40).

By forming a lightening hole (51) communicating with the groove (47) from the outside surface on the upper part of the first regulating member (42), an elastic bending piece (52) is formed on the upper part. The hemispherical projections (53) formed on the upper surface of the center are formed on the upper wall (4b) of the support (4).
Each receiving surface (50) is aligned with the shaft (40) by selectively engaging a plurality of recesses (54) provided on the lower surface of one side at the same pitch as the pitch of each receiving surface (50). At a stable position.

A rectangular step (55) is formed at the upper front corner of the outer surface of the first regulating member (42), and an engagement hole ( 56) is drilled.
An inwardly bent portion (57a) at the rear end of a rod (57) facing the front and rear direction for linking with a first operation lever (60) described later is fitted into the engagement hole (56). I have.

A left-right cylinder shaft (58) is rotatably supported in the left cylinder body (13) at the front of the support base (4).
A core shaft (59) oriented in the same direction is inserted into the cylindrical shaft (58) so as to be relatively rotatable.

The first and second operating levers (6) are provided at the left ends of the core shaft (59) projecting outward from the cylindrical shaft (58) and the cylindrical body (13).
0) (61) (61) (60a) (61a) cylindrical parts having the same outer diameter
These are fitted so that they come into contact with each other with the tubular portion (60a) being outside, and the outside tubular portion (60a) is fixed to the core shaft (59) with a set screw (62).

In the first operation lever (60), the cylinder (6
0a), the operation piece (60b) extends forward from the outer periphery of the operation piece (60b), and the right end of the operation piece (60b) extends in the direction of the cylinder (61a) of the second operation lever (61). ) Is extended by the same length as the length.

In the second operation lever (61), the cylindrical portion (6
The operation piece (61b) extends rearward from the outer periphery of 1a), and the left end of the operation piece (61b) is oriented in the direction of the cylinder (60a) of the first operation lever (60). ) Is extended by the same length as the length.

The core shaft (59) projecting from the right end of the cylindrical shaft (58) is
A shaft hole (63a) formed at the base end of the operating arm (63) facing rearward and upward is fitted into the right end of the extended right end of the side wall (4a) of (4). And are fastened with set screws (64).

The core shaft (59) has a left side surface of the operating arm (63).
By contacting the right side of the bifurcated piece (65) hanging from the lower surface of the upper wall (4b) of the support (4), movement to the left is prevented,
It is retained from the cylinder (13).

The inwardly bent portion (57b) at the front end of the rod (57) is fitted into a left-right engaging hole (63b) formed at the tip of the operating arm (63). I have.

Thus, by rotating the first operating lever (60) downward, the first operating lever (60), the core shaft (59) and the operating arm (6) are rotated.
3) is rotated in the counterclockwise direction in FIG. 6, and the rotation of the operating arm (63) at this time pulls the rod (57) forward, and the first regulating member (42) The projections (53) are
By engaging one by one in step (4), the backrest (5) can be advanced step by step, and the maximum backward tilt angle of the backrest (5) can be limited to a gradually smaller angle.

Conversely, when the first operation lever (60) is turned upward, the first regulating member is actuated in the reverse manner to the above.
(42) is moved backward step by step, and the maximum backward tilt angle of the backrest (5) can be gradually increased.

The first regulating member (42), rod (57), operating arm (63), core shaft (59), first operating lever (60), etc.
A maximum back tilt angle adjusting means (41) for the backrest (5) is formed.

The inner surface of the second restricting member (44) is moved rearward, so that the amount of protrusion of the left end of the shaft (40) into the vertical rotation locus gradually increases. (40) and arm
A substantially wedge-shaped contact portion (66) is formed so as to reduce the downward rotation range of (38).

In this example, the contact portion (66) inclined rearward and downward is provided.
Of the shaft (40) at each step (6)
7) has an arc shape close to the outer diameter of the shaft (40).

A large-diameter projecting shaft (69) having a horizontal hole (68) extending in the front-rear direction is formed in the rear upper portion and the front lower portion of the outer side surface (left side surface) of the second regulating member (44). And a small-diameter protruding shaft (70) are provided to protrude, respectively.

The rear end of the small projecting shaft (70) has a left bottom plate (4).
6) The front end of the tension coil spring (72) locked on the projection (71) projecting outward from the rear end outside is locked.

The lateral hole (68) of the large-diameter projecting shaft (69) is provided with a biasing force stronger than that of the tension coil spring (72), that is, after the tension coil spring (73) directed in the front-rear direction with a large spring constant. An L-shaped locking portion (73a) formed at the end is inserted and locked.

The front end of the tension coil spring (73) is linked to the second operating lever (61) as described later.

A non-circular fitting formed at the left end of the cylindrical shaft (58) is fitted into a small diameter cylindrical portion (61c) formed at the right end of the cylindrical portion (61a) of the second operating lever (61). The part (58a) is fitted, and the second operation lever (61) is connected to the cylinder shaft (58) while being prevented from rotating.

A spur gear (74) is integrally formed at the right end of the cylindrical shaft (58). The spur gear (74) is attached to the upper wall (4b) of the support (4) immediately above. An integral sector gear (77) meshes with a shaft (76) rotatably fitted in a semi-cylindrical bearing recess (75) (see FIG. 8) provided on the lower surface of the shaft.

On the right side of the shaft (76) and the sector gear (77),
The upper end of the operation arm (78) having a substantially semicircular shape in a side view is fixedly formed integrally or integrally formed.

An elastic tongue (7) is provided at the middle portion of the operation arm (78).
9) are integrally formed, and when the operating arm (78) is rotated clockwise about the shaft (76) as shown in FIG. 7, the upper part of the operating arm (78) is With the tongue piece (79), the portion of the core shaft (59) immediately after protruding from the right end of the cylindrical shaft (58) is resiliently gripped, and the operating arm (78) does not rotate counterclockwise from that position Like that.

The front end of the above-described tension coil spring (73) is fixed to a pin (80) projecting rightward from the lower end of the operating arm (78).

Thus, when the second operation lever (61) faces rearward and upward, as shown in FIG.
8) is held in a state where the core shaft (59) is elastically gripped, and the second regulating member (44) is located at the front end.

In this state, the shaft (40) and the arm (38) are
Without being hindered by the abutment portion (66) of the second regulating member (44), the shaft (40) can rotate forward and downward to the maximum until it abuts on the upper surface of the bottom plate (46). The backrest (5) is, for example, oriented substantially vertically.

In this state, when the second operating lever (61) is rotated rearward and downward, and is stopped, for example, in an intermediate and substantially horizontal state, the second operating lever (61) and the cylinder shaft (58) are The spur gear (7
4) rotates clockwise in FIG. 7, and accordingly, the operating arm (78) is moved together with the sector gear (77) and the shaft (76).
Is rotated in the counterclockwise direction, and the rotation of the pin (80) at that time causes the tension coil spring (73) to be pushed in the loosening direction.

At this time, when the backrest (5) is located at a substantially vertical upright position and the shaft (40) is at the position shown in FIG. 7, the rear end surface of the contact portion (66) comes into contact with the front end thereof. The second regulating member (4
4) is prevented from moving backward, and is kept at the position shown in FIG.

Thereafter, when the backrest (5) is tilted backward by the occupant and the arm (38) and the shaft (40) are turned upward, the second regulating member (44) is not clarified until then. )
Is moved backward to a position where the urging forces of the two tension coil springs (72) and (73) are balanced.

Thereafter, when the backrest (5) is raised,
(40) is a contact portion (66) of the second regulating member (44) moved rearward.
Abuts on the receiving surface (67) in the middle stage, for example, and cannot be further lowered. Therefore, after that, the backrest (5)
Is a position slightly inclined backward from the above-described vertical state.

When the second operating lever (61) is rotated to the rear lower position to the maximum, the second regulating member (44) operates the shaft (40) and the arm (38) by the same operation as described above. Waiting for the backrest to pivot upward, it moves to the rear end as shown in FIG. 9, and at this time, the backrest (5) can return only to a position that is considerably inclined backward.

When the second operation lever (61) is turned upward from a position facing rearward and downward to a desired position, the operation arm (78) is turned around the shaft (76) in the reverse operation to that described above. , And the front end of the tension coil spring (73) is pulled forward by the pin (80).

However, at this time, if the shaft (40) is in contact with one of the receiving surfaces (67) and the second regulating member (44) is pressed downward, the second regulating member (44) Does not move immediately, and waits for the backrest (5) to be tilted backward by the seated occupant, and moves forward to set the standing position of the backrest (5) at a desired angle.

When the second operating lever (61) is turned to the upper limit facing rearward and upward, the operating arm (78) causes the core shaft (59) to move by the elastic tongue (79) as shown in FIG. The second restricting member (44) waits until the backrest (5) is once tilted backward, then returns to the front limit, and thereafter returns to the front limit (5). Will be oriented almost vertically.

As described above, after the backrest (5) is slightly inclined backward, the second regulating member (44) is moved to a position where the urging forces of the two tension coil springs (72) and (73) are balanced. Since it is moved, it is possible to prevent each receiving surface (67) of the second regulating member (44) from being worn or damaged.

Further, by using the spur gear (74) and the sector gear (77), the rotation stroke of the second operating lever (61) and the operating arm ( The amount of rotation required in 78) can be harmonized.

The second regulating member (44) and the tension coil spring (7
2) (73), working arm (78), sector gear (77), spur gear (74)
The upright position angle adjusting means (43) is formed by the cylinder shaft (58) having the following, the second operating lever (61), and the like, and the backrest is formed by this and the above-described maximum backward tilt angle adjusting means (41). The tilt range adjusting means (8) of (5) is formed.

The maximum back-tilt angle adjusting means (41) and the upright position angle adjusting means (43) regulate the range of movement of the shaft (40) from above and below, so that the backrest (5) can be moved to a desired position. It can be completely restrained by the backward inclination angle.

A shaft (82) of an operation lever (81) is pivotally supported in the cylindrical body (13) at the right front of the support base (4), and the shaft (82) is connected to the seat (9).
However, since these configurations are not directly related to the present invention, detailed description is omitted.

As shown in FIG. 10, a pin (83) projecting from a part of the inner end surface of the cylindrical shaft (58) is connected to the shaft of the operating arm (78).
Engage with the vertically oriented long hole (84) provided immediately below (76),
With the rotation of the cylindrical shaft (58), the operating arm (78) is rotated about the shaft (76) via the pin (83) and the long hole (84), and thus the above-described operation is performed. The spur gear (74) and the sector gear (77) can be omitted.

[0072]

According to the present invention, the following effects can be obtained. According to the first aspect of the present invention, since the rotation range of the arm that rotates integrally with the back rod is directly regulated by the regulating member, the arm and the back rod can be connected only by a simple shaft. In addition, there is no need to link by a special linking means as in the invention of the prior application, so that the structure can be simplified, the size and weight can be reduced, and the manufacturing cost can be reduced.

According to the second aspect of the present invention, since the shaft is protruded from the distal end of the arm, the contact portion of the regulating member is accurately and always kept in the same state without any one-side contact. You can touch.

According to the third aspect of the present invention, the rotatable range of the backrest can be adjusted stepwise, but can be surely adjusted, and the load on the backrest may cause the regulating member to be pushed back. There is no.

According to the fourth aspect of the invention, the stop position of the regulating member is stabilized, and the operation is ensured.

According to the fifth aspect of the present invention, the elastic pressure holding means can have a simple structure.

According to the sixth aspect of the present invention, the right and left back rods and the arm can be reliably connected in a well-balanced manner, and the support of the left and right back rods is stabilized.

According to the seventh aspect of the present invention, the tilting range adjustment device for the backrest, the torsion bar for returning the backrest to the upright position, and the means for adjusting the urging force thereof are compactly mounted on the pivot of the back rod. Can be arranged in a well-balanced manner.

[Brief description of the drawings]

FIG. 1 is a side view of a chair provided with an embodiment of the present invention.

FIG. 2 is also an exploded perspective view.

FIG. 3 is an exploded perspective view showing the internal structure of the support base.

FIG. 4 is an enlarged cross-sectional plan view taken along the line IV-IV in FIG. 1;

FIG. 5 is a vertical sectional side view taken along line VV of FIG. 4;

FIG. 6 is a vertical sectional side view taken along the line VI-VI of FIG. 4;

FIG. 7 is a vertical sectional side view taken along line VII-VII in FIG. 4;

FIG. 8 is an enlarged vertical sectional front view taken along line VIII-VIII of FIG. 7;

FIG. 9 is a vertical sectional side view similar to FIG. 7, showing another operation state.

FIG. 10 is an enlarged vertical sectional side view of a main part showing a modification of the linking means between the cylinder shaft and the operating arm.

[Explanation of symbols]

 (1) Support leg (2) Caster (3) Pillar (4) Support (4a) Side wall (4b) Upper wall (5) Backrest (6) Back rod (7) Elastic reclining mechanism (8) Adjustable tilt range Device (9) Seat (10) Seat receiver (11) Support rod (12) Armrest (13) (14) Cylindrical body (15) Through hole (16) Cylindrical shaft (17) (18) Bush (19) Receiver (20) Hex hole (21) Set screw (22) Torsion bar (23) Square hole (24) Square hole (25) Adjustment plate (26) Screw hole (27) Tube (28) Rotating handle (29) Adjustment screw (Angle adjusting means) (30) Round hole (31) Notch (32) Insertion hole (33) Recess (34) Bearing (35) Boss (36) Projection shaft (37) Engagement hole (38) Arm (39 ) Hexagonal hole (40) Shaft (41) Maximum backward inclination angle adjusting means (42) First regulating member (43) Angle adjusting means at standing position (44) Second regulating member (45) Boss (46) Bottom plate ( 47) Groove (48) Guide ridge (49) Abutment (50) Receiving surface (51) Lightening hole (52) Elastic bending piece (53) Projection (54) Recess (55) Step (56) Mating hole (57) Rod (57a) (57b) Inwardly bent part (58) Cylindrical shaft (58a) Fitting part (59) Core shaft (60) First operating lever ( 61) Second operation lever (60a) (61a) Tube part (60b) (61b) Operation piece (61c) Small diameter tube part (62) Set screw (63) Operating arm (63a) Shaft hole (63b) Engagement hole (64) Set screw (65) Bifurcated piece (66) Abutment (67) Bearing surface (68) Side hole (69) Protruding shaft (70) Protruding shaft (71) Protrusion (72) (73) Tension coil spring ( 73a) Locking part (74) Spur gear (75) Bearing recess (76) Shaft (77) Sector gear (78) Operating arm (79) Elastic tongue (80) Pin (81) Operating lever (82) Shaft (83) Pin (84) slot

Claims (7)

[Claims] A front end of a back rod extending forward from a lower end of a backrest is pivotally supported on a supporting base for supporting a seat with an axis extending in the left-right direction. Along with providing an arm that rotates integrally, a regulating member that regulates a rotation range of a tip portion of the arm is provided so as to be moved laterally by operating an operation lever disposed below the seat, And, by being moved to one side by the regulating member, the amount of protrusion of the tip of the arm into the rotation locus gradually increases, and the rotation range of the arm is reduced to a substantially wedge shape. A tilting range adjustment device for a backrest in a chair, wherein the abutment portion is provided. 2. The chair according to claim 1, wherein a shaft pointing in the left-right direction is protrudingly provided at a tip portion of the arm, and the shaft comes into contact with a contact portion of a regulating member that moves in the front-rear direction. The device for adjusting the tilting range of the backrest. 3. A tilting range adjusting device for a backrest in a chair according to claim 1, wherein the contact portion of the restricting member has a stepped shape, and the rotation range of the backrest is regulated stepwise. 4. The tilting range of the backrest in a chair according to claim 3, further comprising a resilient pressure holding means for stably stopping the regulating member at a plurality of stop positions corresponding to each step of the stepped contact portion. Adjustment device. 5. A resilient pressure holding means comprising: a resiliently deformable projection provided on a sliding portion of a regulating member with a support base; and a resilient engagement of the projection when the regulating member stops at a plurality of stop positions. 5. A plurality of recesses provided on a support base of the vehicle.
The tilt range adjustment device of the backrest in the chair described in the above. 6. A pair of left and right cylinder shafts are rotatably disposed in left and right cylinders provided on both side walls of the support base, and outer ends of both cylinder shafts are formed by left and right pair of back rods. Attach to the front end,
The base ends of a pair of left and right arms pointing in the same direction are firmly fitted to the inner end, and a shaft pointing in the left / right direction is penetrated at the distal ends of both arms. The movement of this shaft is regulated by a regulating member. The tilt range adjusting device for the backrest in the chair according to any one of claims 1 to 5, wherein 7. A left-right torsion bar is inserted into the left and right cylinder shafts, and both ends of the torsion bar are fixed to left and right back rods, respectively, and the torsion bar is provided between inner ends of the left and right cylinder shafts. Fix the base end of the adjustment plate to the center of
7. An apparatus for adjusting the tilting range of a backrest in a chair according to claim 6, wherein an angle adjusting means for adjusting the angle of the distal end portion of said adjusting plate is disposed in a space sandwiched between the pair of arms and the shaft of the distal end portion. .