JP7469860B2 - Chair - Google Patents

Description

This invention relates to a rocking chair in which the seat slides back and forth independently of the backrest.

In a chair type in which the seat and backrest are separate, a configuration in which the seat is pushed forward when the user leans back on the upper body is disclosed in, for example, Patent Documents 1 to 3. In Patent Document 1, the seat is pushed forward by the backrest, but the seat moves backward independently. On the other hand, in Patent Document 2, the backrest is fixed so that it cannot tilt backward, and only the seat moves forward or backward as the posture of the seated person changes. In either case, in Patent Documents 1 and 2, the rail section that supports the forward and backward sliding of the seat 2 is in a horizontal position.

On the other hand, Patent Document 3 discloses a chair in which the seat is supported by left and right tubular supports so that it can move back and forth, and the tubular supports are tilted so that the front of the supports is higher, allowing the seat to move forward and upward.

Microfilm of Utility Model Publication No. 61-123756 Microfilm of Utility Model Publication No. 62-085239 Japanese Patent Publication No. 61-002364

In a configuration in which the seats slide independently back and forth, the seats are biased backward by a spring, and when the seated person raises their upper body, the seat moves backward by the spring. However, because the weight of the seated person acts on the seat, if the rail section is in a horizontal position as in Patent Documents 1 and 2, there is a problem that it is difficult to move the seat backward unless a spring with a large elastic restoring force is used. Furthermore, if a spring with a large elastic restoring force is used, a new problem arises in that it becomes difficult to move the seat forward when used by a lighter person.

On the other hand, as in Patent Document 3, if the tubular support that supports the seat is tilted diagonally upward, the weight of the seated person acts to move the seat back, so it can be said that the seat can be moved back without increasing the elastic restoring force of the spring.

However, in Patent Document 3, back support columns are erected from the rear ends of the left and right tubular supports, and the backrest is connected to these back support columns so that it can tilt backward, which creates a problem of limited freedom in design.

The objective of the present invention is to improve this current situation.

The present invention includes various configurations, typical examples of which are specified in each claim. Among these, the invention of claim 1 is a generic concept,
"It has a separate seat and backrest,
The backrest is attached to an upper support frame having a right-left longitudinal rotation axis at a position higher than the seat and in front of the rear end of the seat so as to be tiltable backward. Therefore, when a seated person leans against the backrest, the upper support frame rotates downward and the backrest moves downward toward the seat.
The seat has a seat surface that is concave downward when viewed from the vertical section, with the deepest part located toward the rear, and is supported by a base body via a guide means disposed below the seat so that the seat moves upward and forward against the elasticity of the sliding elastic body without being linked to the rearward tilting movement of the backrest.
This is the basic structure .

In addition to the basic configuration above,
"Side supports that are higher than the seat are disposed on the left and right sides of the seat , and the upper support frame having left and right side portions and a rear portion is connected to the left and right side supports so as to surround the seated person from behind, and the backrest is connected to the rear portion of the upper support frame so as to be able to tilt backward .
Furthermore, the side portions of the upper support frame are arranged so as to be exposed from the rear end surface of the upper end portion of the side support body .
The side portion of the upper support frame can also be called a forward arm portion.

The invention of claim 2 is the same as claim 1 ,
"When a person is not leaning against the backrest, at least the lower end of the front surface of the backrest overlaps with the rear portion of the seat in a plan view, and when a person is leaning against the backrest and moving downward and backward, the degree of overlap of the front surface of the backrest in a plan view with respect to the seat when not moving forward increases."
The structure is as follows.

The invention of claim 3 is the same as that of claim 1 ,
"The seat is attached to a seat support body, and the seat support body is supported on the base body by a rear guide means and a front guide means so as to be freely slidable back and forth.
The rear guide means is composed of a rear guide hole in the seat support body, the rear guide shaft being provided on the base body and slidably fitted into the rear guide hole, and the rear guide hole is inclined so as to become higher toward the front,
The front guide means has a roller rotatably held on the base body, and a front support surface provided on the seat support body so as to be supported by the roller, and the front support surface is inclined so as to become higher toward the front.
The structure is as follows.

The invention of claim 4 is a preferred embodiment of claim 3 .
"Both the upper and lower surfaces of the rear guide shaft are formed flat."
As a specific example of claim 4 , claim 5 has the following structure:
"A long groove is formed in the sliding direction of the rear guide shaft on the flat surface of the rear guide shaft."
The structure is as follows.

Effect of claim 1 In the present invention, the seat rises while moving forward, so the weight of the seated person acts to move the seat backward. Therefore, the seat can be moved backward without increasing the restoring force of the sliding elastic body. As a result, even for a light-weight person, the backward movement of the seat can be made smooth while using an elastic body with weak elasticity.

The seat is supported so that it can move back and forth freely by the base body located below it, so there is no need for a tubular support as in Patent Document 3, which allows for greater freedom in design. Also, a configuration in which the seat is guided by tubular supports on the left and right as in Patent Document 3 is difficult to say that it can be easily applied to chairs that use gas cylinders as legs (swivel chairs), but the base body of the present invention can be easily attached to legs made of gas cylinders, making it highly versatile.

In addition, in claim 1 , when the seated person leans back against the backrest, the upper support frame tilts backward to rock the seat, and when the seated person leans back the upper half of the body, the backrest tilts backward against the upper support frame. That is, in claim 1 , the backrest rocks in two stages. This increases the overall rocking angle, providing the seated person with a high level of comfort.

It is also possible to simply tilt the upper support frame backwards while leaning back against the backrest, without bending the upper body backward. In this position, for example, you can lean back against the backrest and tilt your head forward (tuck your chin) to look at a computer (monitor) on your desk. This makes the chair very useful.

The forward pressure exerted by the occupant on the seat may vary depending on whether the upper support frame is simply tilted backwards or the backrest is tilted backwards relative to the upper support frame. However, the difference in forward pressure allows the occupant to choose between a state in which the backrest is simply rocking without the seat moving forward, or a comfortable state in which the upper body is leaned backwards and the seat is also moved forward. In this respect, too, it is highly useful.

Effect of Claim 3 In chairs used in offices, the seats are generally constructed with a seat inner shell (seat plate) made of synthetic resin covered with seat cushioning material. In this case, it is possible to attach the seat inner shell directly to the base body, but in this case, the structure of the seat inner shell may become complicated in terms of ensuring strength, etc., and it may be difficult to ensure cushioning by allowing deformation due to the weight of the person sitting on it.

In contrast, if the seat is provided on a seat support body and the seat support body is slidably attached to the base body as in claim 3 , the seat support body can function as a strength member, which increases the freedom of seat design and makes it easy to ensure cushioning by allowing deformation due to the weight of the seated person. This contributes to improving the quality of the chair.

Furthermore, when the configuration of claim 3 is adopted, the rear guide means, which is a combination of the rear guide hole and the rear guide shaft, ensures the stability of the movement of the seat support body, while the front guide means uses rollers to roll, so resistance is significantly reduced. Therefore, with claim 3 , the seat can be slid smoothly while remaining stable.

Effects of claims 4 and 5
In claim 4 , the contact area between the rear guide shaft and the rear guide hole can be increased, so frictional resistance can be suppressed to further improve the smoothness of sliding and durability. In this case, if there is simple surface contact, the rear guide shaft may get stuck in the rear guide hole, but if a groove is formed on the flat surface as in claim 5 , the rear guide shaft and the rear guide hole are in a state close to line contact, which has the advantage of preventing the sticking phenomenon and ensuring smooth sliding. In addition, if grease is applied to the sliding surface, the grease can be retained in the groove, which is preferable because it ensures smooth sliding for a long period of time.

1A and 1B are diagrams showing the appearance of a chair according to a first embodiment, in which (A) is an oblique view seen from above the front, (B) is a partial front view, (C) is an oblique view seen from above the rear, and (D) is an oblique view seen from below the rear. 1A is a plan view omitting the leg device, FIG. 1B is a side view, and FIG. 1A is a partial side view in a state before being locked, and FIG. 1B is a side view in a locked state. 2C is a sectional view taken along line IVC-IVC in FIG. 2C; FIG. 2C is a sectional view taken along line IVC-IVC in FIG. 2C; FIG. 3 is a cross-sectional view taken along line V-V of FIG. 13 is a perspective view showing the seat separated to expose the seat support member. FIG. 13 is a perspective view of a seat support member separated from a base body. FIG. 1A is a vertical cross-sectional side view of the left-right center portion of the seat portion, and FIG. FIG. 4 is an exploded perspective view of the seat support member in an upside-down state. 10 is a cross-sectional view of the seat portion as seen from the X-X direction in FIG. 9 . 10A is a cross-sectional view of the seat portion as viewed from the direction of XI-XI in FIG. 9, (B) is a perspective view of only the bush and the rear guide shaft, (C) is a side view of the bush and the rear guide shaft in a fully forward position, and (D) is a perspective view of the rear guide shaft. 11A and 11B are diagrams showing a second embodiment applied to a four-legged leg device, in which (A) is a perspective view seen from above the front, (B) is a perspective view seen from below the front, and (C) is an exploded perspective view.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the questions of front, back, left and right are used to specify directions, but these directions are based on the state seen by a person normally seated in a chair. The front viewing direction is the direction facing the seated person.

(1) Overview of the Chair First, an overview of the chair will be described with reference to Figures 1 to 3. As shown in Figure 1, the chair has, as its basic elements, a leg device 1, a seat 2, and a backrest 3. The leg device 1 has a structure in which a leg column 5 made of a gas cylinder is erected at the center of a grounding body 4 having a plurality (five) of branch arms, and casters are provided at the tip of each arm. Therefore, this embodiment is applied to a swivel chair.

As shown in FIG. 1(D), a base body 6, which is substantially rectangular in bottom view (plan view), is fixed to the upper end of the leg 5. A seat support body 7 is attached to the base body 6 so that it can slide back and forth, and the seat 2 is attached to the upper surface of the seat support body 7. The base body 6 is, for example, an aluminum die-cast product, and the seat support body 7 is, for example, a molded product made of synthetic resin.

As will be described in more detail later, the seat support body 7 is biased to a retracted position by a spring, which is an example of a sliding elastic body, and when the occupant's body becomes stretched during rocking, the seat 2 and seat support body 7 can be pushed forward by the buttocks. Figure 3 shows the seat 2 in a forward position. As can be seen by comparing Figures 3(A) and (B), in this embodiment, the seat support body 7 and seat 2 move forward while rising slightly.

The chair is equipped with an upper support frame 8 positioned higher than the seat 2 so as to surround the seated person from behind. The upper support frame 8 therefore has left and right side sections 9 located on the left and right sides of the seated person and the backrest 3, and a rear section 10 located behind the seated person and the backrest 3, and the backrest 3 is connected to the rear section 10 so that it can be tilted backwards. The rotation axis O of the backrest 3 is located in front of the rear end of the backrest 3.

In this embodiment, the backrest 3 is curved in a backward-facing (forward-facing) manner in plan view so as to embrace the body of the seated occupant from behind, and the rear portion 10 of the upper support frame 8 is curved to follow the curvature of the backrest 3.

That is, in a plan view, the rear portion 10 of the upper support frame 8 and the rear surface of the backrest 3 are similar in shape. Furthermore, the side portions 9 are also curved in a plan view. Therefore, the upper support frame 8 as a whole is curved in a shape close to a circular arc, and as shown in Figure 2, there is a certain amount of gap E between the upper support frame 8 and the backrest 3. Furthermore, the upper support frame 8 is generally in a horizontal position.
As shown in FIG. 2(B), the backrest 3 is tilted slightly backward in side view when in the non-rocking state, and as shown in FIG. 2(A), in the non-rocking state when no one is leaning on it, the lower part of the backrest 3 overlaps with the rear part of the seat 2 in a plan view.

The left and right side parts 9 of the upper support frame 8 are connected to side supports 13 arranged on the left and right sides of the seat 2 so as to be able to tilt backward. The side supports 13 are, for example, aluminum die-cast products, and have a vertically long, plate-shaped support part 14 and a front-rear long, substantially circular upper horizontal part 15 integrally formed at the upper end of the side support 13. The side parts 9 of the upper support frame 8 are connected to the rear part of the upper horizontal part 15 so as to be able to tilt backward against elasticity. Therefore, the side parts 9 of the upper support frame 8 are exposed from the rear end surface of the upper horizontal part 15 that constitutes the upper end part of the side support 13. The upper horizontal part 15 is covered with an elastomer-based protective cover 16.

A base 17 is integrally formed at the lower end of the support pillar 14 of the side support 13, and wraps around underneath the seat 2. The tip of the base 17 is fitted into an engagement hole 18 (see Figures 1(D) and 2(B)) formed in the base body 6, and the tip is fixed to the base body 6 with a bolt.

As mentioned above, the leg pillar 5 is made of a gas cylinder, and when the gas cylinder is unlocked, the height of the seat 2 and backrest 3 can be freely adjusted. As shown in Figures 1(A) and (C), for example, a knob 19 for unlocking the gas cylinder is attached to the upper horizontal part 15 of the right-side side support 13 so that it can be rotated around the axis of the upper horizontal part 15. The knob 19 can be rotated in either direction, and the gas cylinder is unlocked when it is rotated in either direction.

The rotation of the knob 19 is transmitted to the unlock lever via a wire inserted through the tube. As shown by the dashed line in Figures 2(A) and 2(B), it is also possible to attach an elbow rest 20 to the upper horizontal portion 15 of the side support 13.

(2) Rocking Movement As shown in FIG. 3, in this embodiment, when a seated occupant leans against the backrest 3, the upper support frame 8 first tilts backward relative to the side support 13, thereby performing the first stage of rocking, and the backrest 3 descends so as to approach the seat 2.
Next, when the seated person leans his/her upper body backward, the backrest 3 tilts backward with respect to the upper support frame 8, and the second stage of rocking is performed. Therefore, even if the rotation angle of the upper support frame 8 and the rotation angle of the backrest 3 are not so large, the overall backward tilt angle can be made large. Therefore, the seated person can be provided with a high level of comfort despite the simple structure.
As described above, when the backrest 3 is in the non-rocking state, its lower part overlaps with the rear of the seat 2 in a plan view. However, when the backrest 3 is lowered and tilted backward, the overlap between the backrest 3 and the seat 2 becomes greater in a plan view, as can be seen by comparing Figures 2(A) and 2(B).

In addition, because the pivot point of the upper support frame 8 is higher than the seat 2 and is in a horizontal position, the backrest 3 does not move backwards when the upper support frame 8 tilts backwards. Therefore, there is no problem with the body moving backwards too much due to rocking, causing inconvenience to the person behind.

In addition, when the upper body is tilted backward, the body tends to stretch, but in this embodiment, the seat moves forward, allowing the body to stretch. Therefore, the occupant can enjoy high comfort without being rocked in a cramped position. In other words, by combining two-stage rocking with forward movement of the seat, high rocking function and high comfort can be ensured without moving the backrest 3 backward.

For example, in office work, a person may look at a monitor on a desk while in a rocking position. In this case, the person will look at the monitor while leaning against the backrest 3 without bending the upper body and with the chin tucked. In this embodiment, however, the upper support frame 8 tilts backwards by leaning against the backrest 3 without bending the upper body, so the monitor can be viewed while maintaining a stable rocking position.

On the other hand, if the upper body is leaned backward, the backrest 3 tilts backward relative to the upper support frame 8, providing a high level of rest. Therefore, the backrest 3 can be tilted backward according to the needs of the seated person.

As shown in Figures 2(B) and (C), the attachment position of the backrest 3 to the upper support frame 8 is located below the vertical midpoint of the backrest 3. Therefore, when the backrest 3 tilts backward relative to the upper support frame 8, a large moment is applied to the backrest 3, making it easier to tilt the backrest 3 backward. This also prevents the lower end of the backrest 3 from hitting the body of the seated person too hard.

(3) Backrest Connection Structure Just to be clear, a brief explanation will be given of the connection structure of the backrest 3 to the rear portion 10 of the upper support frame 8 and the connection structure of the support frame 8 to the upper horizontal portion 15. First, the connection structure of the backrest 3 to the rear portion 10 of the upper support frame 8 will be explained mainly with reference to FIG.

As shown in FIG. 1(B), the backrest 3 comprises a back inner shell (back panel) 22 and a back cushion material 23 attached to its front (and rear) surface, and the back cushion material 23 is covered with a skin material 24. The skin material 24 is bag-shaped and also covers the rear surface of the back inner shell 22. The back cushion material 23 can be attached to the back inner shell by insert molding.

As can be seen from FIG. 4(A), the back inner shell 22 is a synthetic resin molding, and a number of reinforcing ribs 25 extending vertically and horizontally are formed on the rear surface of the back inner shell 22. Two boss bodies 26, one on the left and one on the right, protrude forward from the rear portion 10 of the upper support frame 8, and a support bracket 27 is fixed to the boss bodies 26. The support bracket 27 includes a pipe 28 fitted from the outside into the boss bodies 26 and left and right forward-facing side plates 27a, and the pipe 28 is fixed to the boss bodies 26 with screws 30. The boss bodies 26 are welded to the rear portion 10 of the upper support frame 8.

In front of the receiving bracket 27, a vertically elongated push bracket 31 having left and right rearward-facing side plates 31a is arranged, and the receiving bracket 27 is arranged between the left and right side plates 31a of the push bracket 31, and both side plates 27a, 31a are connected by a left and right elongated support shaft 33. In addition, a cellust (rubber) 34 is arranged between the push bracket 31 and the receiving bracket 27 and above the support shaft 33 as a locking elastic body.

The receiving bracket 27 and the pushing bracket 31 are covered from behind by a synthetic resin cover 35 that is vertically long, and the receiving bracket 27, the pushing bracket 31, and the cover 35 form a connecting unit. The rear surface of the back inner shell 22 has a vertically long rectangular recess 36 formed by partially removing the reinforcing rib 25, and the connecting unit consisting of the receiving bracket 27, the pushing bracket 31, and the cover 35 is fitted into this rectangular recess 36 from behind.

The pipe 28 of the receiving bracket 27 is covered with a cylindrical protective cap 37 made of a rubber material such as elastomer. The bottom of the protective cap 37 has an escape hole 38 to allow the screw 30 to pass through.

The push bracket 31 is fixed to the back inner shell 22 only at its lower part with a screw 42. A T-shaped nut 39 into which the screw 42 is screwed is disposed on the front side of the back inner shell 22. The nut 39 is fitted from the front into a nut holding hole 40 formed in the back inner shell 22. Engagement claws 35a are formed on both the upper and lower ends of the cover 35, while engagement holes 22a are formed in the back inner shell 22 with which the engagement claws 35a engage after elastic deformation.

(4) Mounting Structure of Upper Support Frame Next, the connection structure of the upper support frame 8 to the side support 13 will be described with reference to Figure 5. As mentioned above, the right side support 13 is provided with a knob 19 for unlocking the leg column 5 (gas cylinder). Therefore, the left and right side supports 13 have slightly different structures, but the connection structure of the upper support frame 8 is the same for both sides. Here, the left side portion, which does not have the knob 19, will be described.

A push bracket 48 having left and right upward side plates 48a is fixed to the side portion 9 of the upper support frame 8. The push bracket 48 has a channel-shaped portion having the upward side plates 48a and a boss portion 49 located behind it, and the boss portion 49 is fixed to the side portion 9 of the upper support frame 8 by welding. A flange 50 that abuts against the front end surface of the upper support frame 8 is integrally formed at the base of the boss portion 49. The push bracket 48 is made of cast steel.

A flat portion 51 is formed in the rear half of the upper horizontal portion 15 of the side support 13, and a square block portion 52 and a tapped hole 53 located behind the block portion 52 are formed in the flat portion 51. A channel-shaped lower support bracket 54 having an upwardly facing side plate 54a is placed on top of the flat portion 51, and the lower support bracket 54 is fixed to the flat portion 51 by a screw 55 screwed into the tapped hole 53. A notch is formed in the front portion of the lower support bracket 54 to avoid interference with the block portion 52, and the side plate 54a of the lower support bracket 54 is located on the left and right sides of the block portion 52.

An upper support bracket 57 having a downward side plate 57a fits inside the lower support bracket 54. The upper support bracket 57 holds the block portion 52 from above, and is fixed to the block portion 52 by screws 56.

The push bracket 48 is partially inserted inside the upper support bracket 57, and the rear of the side plates 57a, 54a of the upper and lower support brackets 57, 54 and the rear of the side plate 48a of the push bracket 48 are connected by a left-right long support shaft 60. A block-shaped elastic body 61 made of resin rubber such as urethane foam elastomer is interposed between the push bracket 48 and the upper support bracket 57.

The upper and lower support brackets 57, 54 are fixed so that they cannot rotate, while the push bracket 48 is connected by a single support shaft 60, and the left and right side plates 48a of the push bracket 48 form inclined sections 62 that become lower toward the front. Therefore, the upper support frame 8 can tilt backward by the spread angle θ2 between the inclined section 62 and the upper support bracket 57 around the axis of the support shaft 60 against the elasticity of the elastic body 61. The elastic body 61 is pre-compressed. The push bracket 48 and support shaft 60 are fixed by a screw 64 screwed into the support shaft 60 from above.

The lower support bracket 54 has a downwardly bulging downward protrusion 54b into which the head of the screw 55 fits, and correspondingly, the flat portion 51 of the upper horizontal portion 15 has a recess 51a into which the downward protrusion 54b fits. The upper horizontal portion 15 of the side support 13 is covered by the protective cover 16 already described. The rear portion of the protective cover 16 is a cylinder 16a, and a downward opening is formed in front of it. The front end of the protective cover 16 is closed, but it is also possible to open the front end and cover it with a cap.

(5) Structure of the seat Next, the structure of the seat will be described with reference to Figures 6 to 11. As shown in Figure 7, the base body 6 is in the form of a shallow tray that is generally rectangular in plan view and opens upward. In the approximate center of the base body 6, as shown in Figure 8(A), there is a boss hole 70 into which the upper end of the leg 5 (more precisely, the inner tube of the gas cylinder that constitutes the leg 5) is fitted from below. In order to ensure the necessary height for the boss hole 70, a downward-facing tube portion 71 is formed in the base body 6. The inner peripheral surface of the boss hole 70 and the outer peripheral surface of the upper part of the leg 5 are tapered, with the diameter decreasing toward the top.

For example, as shown in FIG. 8(A), a push valve 72 for unlocking is protruded from the upper end of the leg column 5, and a push valve pushing mechanism 73 for pushing the push valve 70 is disposed on the base body 6. The push valve pushing mechanism 73 is composed of a lever and other components, but as it is not relevant to the present application, a description thereof will be omitted.

The seat 2 includes a synthetic resin seat inner shell (seat plate) 2a shown in FIG. 6(A), a seat cushion material 2b shown in FIG. 8(A), and a skin material (not shown) that covers the seat cushion material 2b, and the seat inner shell 2a is attached to the seat support body 7. The seat inner shell 2a is omitted in FIG. 8(A).

As partially shown in Figures 6(B) and 7, the seat support body 7 is formed with a group of front and rear engagement holes 77 into which downward engagement claws (not shown) provided on the seat inner shell 2a fit and engage. An elastic body 78 that supports the seat inner shell 2a is disposed at the front of the seat support body 7. As shown in Figures 6(B) and 7, the seat support body 7 is formed with a large opening 79 that is rectangular in plan view at its center. The seat support body 7 is formed in the shape of a shallow tray, and a large number of reinforcing ribs 80 extending vertically and horizontally are formed inside.

As already mentioned, the seat support body 7 is attached to the base body 6 so that it can slide back and forth. As a sliding means, first, as shown in FIG. 7, a front long hole 81 is formed on both the left and right sides of the front of the seat support body 7, penetrating vertically in the front-to-back direction, and a front guide shaft 82 is inserted into this front long hole 81 and fixed to the base body 6.

The front guide shaft 82 is formed with a flange 82a that holds the seat support body 7 facing upward so that it cannot be separated, and is fixed to the base body 6 with a screw (not shown). Therefore, the base body 6 is formed with a tapped hole 83 into which the screw screws. The front long hole 81 and the front guide shaft 82 form a disengagement prevention part that guides the front part of the seat support body 7 back and forth without disengaging from the base body 6.

For example, as shown in FIG. 7, a pair of bearing pieces 84 are provided on the left and right sides of the rear of the seat support body 7, protruding downward, while a longitudinal support rib 85 is formed on the base body 6, sandwiched between the pair of bearing pieces 84, and a longitudinal rear guide hole 86 is formed in the support rib 85, and a longitudinal rear guide shaft 87 is inserted through the pair of bearing pieces 84 and the rear guide hole 86. Thus, the rear guide hole 86 and the rear guide shaft 87 form a rear guide means for sliding the rear of the seat support body 7 back and forth.

For example, as shown in FIG. 7, a pair of bearing pieces 84 are provided downward at two locations on the left and right sides of the rear of the seat support body 7, while a longitudinal support rib 85 is formed on the base body 6, sandwiched between the pair of bearing pieces 84, and a longitudinal rear guide hole 86 is formed in the support rib 85. A longitudinal rear guide shaft 87 is inserted through the pair of bearing pieces 84 and the rear guide hole 86 via a bush 88. Thus, the rear of the seat support body 7 is connected to the base 6 via the rear guide shaft 87 so as to be freely slidable back and forth. The bush 88 is made of resin with excellent abrasion resistance, and has a fairly large width in order to improve durability. The bearing pieces 84 are formed at the opening 79, so that the bush 88 and rear guide shaft 87 can be easily attached.

For example, as shown in FIG. 11, the rear guide shaft 87 has a hollow structure, and a metal axle 89 is inserted inside. The axle 89 is a measure to improve strength, but the entire rear guide shaft 87 may be formed as a solid structure. Also, as shown in FIG. 11, the rear guide shaft 87 has upper and lower flat surfaces 87a, which are set to come into surface contact with the bush 88 (in FIG. 9, the flat surface 87a faces forward and backward, but in reality, as shown in FIG. 11, the flat surface 87a faces upward and downward). This makes it possible to suppress wear, and to reduce the surface pressure between the rear guide shaft 87 and the bush 88, making the movement of the rear guide shaft 87 smoother.

As shown in FIG. 11(D), the flat surface 87b of the rear guide shaft 87 has multiple long grooves 87b arranged in parallel in a direction perpendicular to the shaft center (sliding direction). Therefore, the flat surface 87a is divided into multiple linear surfaces (or band-shaped surfaces). When grease is applied to the contact surface between the rear guide shaft 87 and the bush 88, the grease can be retained by the grooves 87b.

In FIG. 11(A), the rear guide shaft 87 abuts against the rear end of the rear guide hole 86 when fully retracted, but in the example shown in FIG. 11(C), when the rear guide shaft 87 is fully retracted, a small gap S is set between the rear surface of the rear guide shaft 87 and the rear surface of the rear guide hole 86.

Furthermore, corresponding to the structure of Fig. 11(C), as shown in Fig. 8(B), a fixed stopper rib 6a is provided at the rear or wall of the base 6 in a substantially vertical position, while a movable stopper rib 7a is provided at the rear of the seat support body 7, overlapping the stopper rib 6a from the front, and a cushioning sheet (not shown) such as a rubber sheet or sponge sheet is affixed to one or both of them. With this configuration, when the seat 2 (and the seat support body 7) is fully retracted, the rear guide shaft 87 does not collide with the rear end of the rear guide hole 86, so no impact noise is generated.

Furthermore, as shown in Fig. 9 and Fig. 11(A), a pair of left and right roller receiving recesses 90 that open upward are formed in the front of the base body 6, and rollers 91 with their axes extending in the left and right directions are arranged in the roller receiving recesses 90 so that they can roll freely, and the seat receiving body 7 is supported by the left and right rollers 91. A metal receiving plate 92 that abuts against the rollers 91 from above is attached to a recess formed in the underside of the seat receiving body 7. Therefore, the receiving plate 92 forms a front support surface. In addition, the rollers 91 and receiving plate 92, the front long hole 81, and the front guide shaft 82 form a front guide means that holds the front and rear of the seat receiving body 7 so that it can be freely moved forward and backward.

As shown in FIG. 11A, in this embodiment, the rear guide hole 86 (and bush 88) and the receiving plate 92 are inclined at a slight angle θ3 with respect to the horizontal plane so that they are higher toward the front. Therefore, the seat 2 and the seat receiving body 7 move forward while rising slightly. The inclination angle θ3 is set to about 3°.

As shown in Figures 9 and 10, a longitudinal spring (compression coil spring) 93 is disposed in a front-rear direction in a portion of the base body 6 toward the front as an example of a sliding elastic body that provides elastic resistance to the forward movement of the seat support body 7. The spring 93 is disposed in a bracket groove 94 formed in the base body 6, and as shown in Figure 10, the front end is supported by a front wall surface 95 of the bracket groove 94, and the rear end is supported by a rear bracket 96 provided on the seat support body 7.

The rear bracket 96 is positioned across the opening 79. The front wall surface 95 and the rear bracket 96 are formed with protrusions 95a, 96a that hold the spring 93 in place so that it cannot shift. The spring 93 is positioned in a pre-compressed state. In addition, the front part of the spring 93 is held in place by a stopper 94a fixed to the base body 6 so that it cannot move upward.

In this embodiment, the rear guide hole 86 and the receiving plate 92 are inclined so that they are higher toward the front, so that the weight of the seated person causes the seat 2 to return to its original position. For this reason, it is not necessary to make the elastic restoring force of the spring 93 excessively strong. Therefore, even a light-weight person can easily move the seat 2 backwards when they sit up.

In this case, a gap is created between the seat support body 7 and the base body 6 due to the forward movement of the seat 2, but because the inclination angle is small at about 3°, even if you place your fingertips in the gap, they will not get caught. Therefore, the backward movement of the seat 2 can be ensured while ensuring safety.

In addition, the support rib 85 and bushing 88 that provide the rear guide hole 86 are sandwiched between the left and right bearing pieces 84, so the rear of the seat support body 7 is held immovable from side to side. On the other hand, the front of the seat support body 7 is held immovable from side to side and from coming off upwards, as the front guide shaft 82 fits into the front long hole 81. Therefore, the seat support body 7 can slide back and forth without swinging left and right. This provides excellent stability.

Furthermore, a flat surface 87a is formed on the rear guide shaft 87, and the rear guide shaft 87 and the bush 88 are in surface contact, reducing frictional resistance. On the other hand, the friction between the roller 90 and the receiving plate 92 is also extremely small, so the frictional resistance to the forward and backward sliding of the seat receiving body 7 is extremely small. This allows the seat 2 to move forward smoothly, contributing to improved comfort.

In particular, when multiple grooves 87b are formed on the flat surface 87a as in the embodiment, the flat surface 87a becomes a collection of band-shaped surfaces (or linear surfaces), which determines the direction of sliding and increases stability, providing the advantage of allowing for extremely smooth sliding without jamming.

(6) Other Examples of Leg Device In the above embodiment, the leg device 1 uses the leg pillar 5 made of a gas cylinder, but in the second embodiment shown in Fig. 12, the leg device 100 has four rod legs 101. Therefore, the chair of the second embodiment is of a non-rotating type.

A horizontal portion 101a is bent at the upper end of each rod leg 101, and the horizontal portion 101a is fixed to the bowl-shaped base body 102 by welding. A tapered boss protrusion 103 is fixed to the center of the base body 102, and fits from below into the boss hole 70 of the seat support body 7. Therefore, the same seat support body 7 is shared by a chair equipped with a gas cylinder type leg device 1 and a chair equipped with a rod leg type leg device 100.

This allows the overall costs of parts and assembly to be reduced when preparing multiple types of chairs with different leg device 1, 100 structures. If the leg device 100 is a rod-leg type, the knob 19 for adjusting the height of the seat 2 is not required, so no processing is required to provide the knob 19 on either the left or right side support 13. However, the knob 19 may remain attached (the knob 19 may be fixed so that it cannot rotate).

The horizontal part 101a of the rod foot 101 penetrates the lower outer periphery of the base body 102 and enters the inside of the base body 102. This provides a strong fixation. The seat support body 7 is supported by a flange 102a provided on the base body 102. This allows the seat support body 7 to be stably supported. A decorative tube 104 made of wood or the like is attached to the rod foot 101, but it may be left exposed.

Although the embodiment of the present invention has been described above, the present invention can be embodied in various other ways. For example, as a guide means, it is possible to fix a longitudinal groove-shaped guide rail to the base body and fit a slider provided on the seat support body into the groove-shaped guide rail.

The present invention can be embodied in a chair. Therefore, it can be used industrially.

2 Seat 3 Backrest 5 Legs (gas cylinder)
6 Base body 7 Seat support body 8 Upper support frame 9 Side part of upper support frame (forward arm part)
13 Side support 14 Support pillar 15 Upper horizontal portion 81 Front long hole constituting the front guide means 82 Front guide shaft constituting the front guide means 85 Support rib 86 Rear guide hole constituting the rear guide means 87 Rear guide shaft constituting the rear guide means 87a Flat surface 87b Groove 88 Bush 90 Recess 91 Roller constituting the front guide means 92 Receiving plate (front support surface) constituting the front guide means

Claims (5)

It has a seat and a backrest that are separate from each other,
The backrest is attached to an upper support frame having a right-left longitudinal rotation axis at a position higher than the seat and in front of the rear end of the seat so as to be tiltable backward. Therefore, when a seated person leans against the backrest, the upper support frame rotates downward and the backrest moves downward toward the seat.
The seat has a seat surface that is concave downward when viewed from the vertical section, and the deepest part is located toward the rear, and the seat is supported by a base body via a guide means arranged below the seat so as to move forward while rising against the elasticity of the sliding elastic body without being linked to the backward tilting movement of the backrest,
Side supports higher than the seat are disposed on the left and right sides of the seat, and the upper support frame having left and right side portions and a rear portion is connected to the left and right side supports so as to surround the seated person from behind and can be tilted backward, and the backrest is connected to the rear portion of the upper support frame so as to be tilted backward,
Furthermore, the side portion of the upper support frame is arranged so as to be exposed from the rear end surface of the upper end portion of the side support body.
Chair. When a person is not leaning on the backrest, at least the lower end of the front surface of the backrest overlaps with the rear portion of the seat in a plan view, and when a person is leaning on the backrest and moving downward and tilting backward, the degree of overlap of the front surface of the backrest with the seat in a non-forward moving state is increased in a plan view.
2. A chair as claimed in claim 1. The seat is attached to a seat support body, and the seat support body is supported on the base body by a rear guide means and a front guide means so as to be slidable back and forth.
The rear guide means is composed of a rear guide hole in the seat support body, the rear guide shaft being provided on the base body and slidably fitted into the rear guide hole, and the rear guide hole is inclined so as to become higher toward the front,
The front guide means has a roller rotatably held on the base body, and a front support surface provided on the seat support body so as to be supported by the roller, and the front support surface is inclined so as to become higher toward the front.
2. A chair as claimed in claim 1 . The upper and lower surfaces of the rear guide shaft are formed flat.
A chair as claimed in claim 3 . A long groove is formed in the sliding direction of the rear guide shaft on the flat surface of the rear guide shaft.
A chair as claimed in claim 4.

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