JPH0795966B2 - Chair tilting device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a structure of an office or work chair.

[Conventional technology]

In office chairs or work chairs, when the user leans on the backrest to take a comfortable posture, there are various means for giving the backrest cushioning property (strength of resistance to support the leaning load). For example, in Japanese Examined Patent Publication No. 44-12548,
The lower surface of the front end of the seat plate is rotatably attached to the upper part of the front leg, while the upper back surface of the backrest is rotatably attached to the upper end of the rear leg, and the rear end of the seat plate and the lower end of the backrest are omitted from a side view. There is disclosed a configuration in which U-shaped leaf springs are connected and the lower surface of the leaf spring is supported by connecting members of front and rear legs so as to be movable back and forth.

[Problems to be Solved by the Invention]

According to this structure, when a weight is applied to the seat plate, the rear end portion of the seat plate descends, and in response to this, the lower end of the backrest moves forward through the U-shaped plate spring, and The degree of elastic deformation that occurs in the U-shaped portion also changes. That is, when a heavy (light) person sits, the amount of elastic deformation of the leaf spring is large (small).
Therefore, the cushioning property of the backrest also becomes hard (soft).

However, according to the above-mentioned prior art, the degree of lowering of the rear portion of the seat plate changes according to the weight of the user's weight and the lower part of the backrest connected to the leaf spring moves forward, whereby the seatboard and the backrest are moved. The main purpose is to reduce the change in the angle of intersection with the seat regardless of the weight of the person sitting on the seat, and the upper back surface of the backrest is rotatably supported with respect to the rear legs. There is a drawback that the position of the upper part of the backrest, where the largest load should be applied, does not tilt back and forth, making it difficult to take a comfortable posture.

In order to eliminate this drawback, in Japanese Utility Model Laid-Open No. 62-109642 filed earlier by the present applicant, the lower end of the support rod of the backrest is connected to the rear part of the seat plate via a link so as to be rotatable back and forth. , The support rod and the front part of the lower surface of the seat plate are connected by a gas cylinder,
In the free state of the gas cylinder, the upper side of the backrest can be largely tilted backward against the elastic force of the gas cylinder.

By the way, the elastic force of the gas cylinder in the free state is directly proportional to the amount of protrusion of the piston rod with respect to the cylinder, and the spring force as the so-called initial value at the beginning of the backward tilt of the back is the same. It was difficult to automatically adjust the strength and weakness of the spring force according to the load leaning on the backrest and the lightness and weight of the body.

The present invention has been made in view of these conventional drawbacks.

[Means for Solving the Problems]

Therefore, in the present invention, the front portion of the seat plate is pivotally supported on the front portion of the support base of the chair so as to be vertically rotatable, and the backrest member that tilts back and forth integrally with the seat plate is provided upright at the rear portion of the seat plate. The upper back member is connected to the lower back member so that the upper back member can be tilted back and forth, and the base end of the link is pivotally attached to the support base and extends rearward from the pivot point of the seat plate. An urging spring is mounted between the rear portion and the backrest member, and in order to increase the bending amount of the urging spring in response to the rearward tilting of the seat plate, the pressing piece at the rear portion of the seat plate is used to move the link back and forth. The configuration is such that the midway portion is pressed so as to rotate downward.

[Operation and effect of the invention]

According to the present invention, since the backrest lower member is integrally attached to the seat plate, and the backrest upper member is connected to the upper portion of the backrest lower member so as to tilt back and forth, the seatboard When seated on, the seat plate tilts backward with respect to the support base around its front side, and both the back lower member and the back upper member tilt rearward in conjunction with this rear tilting. .

Then, a link having a base end pivotally attached to the support base is extended rearward, and the rear portion and the backrest member are mounted by biasing springs. Since the pressing piece pushes downward, the rear part of the link also descends when the seat plate is tilted backward, and a spring elastic force can be applied to the backrest member via the biasing spring whose lower end is attached to this. .

At this time, the base end of the link, the support base, and the pivot point are located rearward of the pivotal fulcrum of the seat plate front portion, and the front and rear midway portions of the link are pressed downward by the press plate at the seat plate rear portion. Therefore, in general, the downward rotation angle of the link can be made larger than the rearward inclination angle of the seat plate. In addition to this,
By setting the rearward length of the link to a predetermined value, the lowering amount of the lower end of the biasing spring can be made larger than the lowering amount of the backrest member to which the upper end of the biasing spring is attached.

In other words, when the seat plate tilts backward, the tilt angle and the amount of bending of the bias spring as the initial value have a proportional relationship.

Therefore, since the backward tilt angle of the seat plate when a heavy person sits is large, generally, the thick abdomen of a heavy person is not pressed, and moreover, as the initial value of the backrest member against the lean load, The elastic force, that is, the cushioning resistance increases, and when a heavy person takes a comfortable posture leaning on the backrest member, the backrest member leans backward more than necessary and feels anxiety. Doesn't feel too soft.

On the other hand, when a lighter person leans against the backrest member,
Since the seat plate has a small rearward inclination angle and the elastic force as the initial value of the biasing spring with respect to the backrest member is small, the backrest member can be slightly tilted backward even with a small leaning load, and the cushion is You can feel soft.

As described above, according to the present invention, the cushioning property of the backrest member can be automatically adjusted to be substantially the same regardless of the weight of the person sitting on the chair, which is excellent in ergonomics. You can provide a chair.

〔Example〕

Next, an example will be described. FIG. 1 shows an office chair 1.
FIG. 3 is a side cross-sectional view showing a support base 3 fixed to the upper end of a leg support 2 having casters (not shown) at the lower end, and the front portion of the support base 3 and the lower front portion of the seat plate 4 are supported by a support pin. 5, a buffer spring means 6 is interposed between the support base 3 and the lower surface of the seat plate 4.

Reference numeral 7 is a hollow back support frame that stands upright from the rear end of the seat plate 4, and a back support member 8 is provided on the front surface of the back support frame. A hollow upper frame 10 having a backrest member 9 on the front side is connected to a pin 17 through a bracket 11 and a connecting rod 12 so as to be tiltable in the front and rear direction at the upper portion. The bracket 11 may be directly connected so that it can be tilted back and forth.

Reference numeral 13 is a link pivotally mounted at a position rearward of the support pin 5 on the support base 3 so as to pivot up and down through a shaft 14, and the link 13 is rearward toward the back support frame body 9. An urging spring 15 is mounted on the rear portion of the link 13 and the connecting rod 12 or the backrest member 9 extending.

Reference numeral 16 denotes a pressing piece projecting downward on the rear portion of the lower surface of the seat plate 4 or on the lower part of the back support frame body 8 which tilts integrally with the lower surface of the seat plate 4, and the pressing piece 16 directs the middle portion of the front and rear of the link 13 downward. It is pressed so as to rotate.

The seat plate 4, the backrest lower member 8 and the backrest upper member 9 have a so-called cushion material such as urethane foam resin inside.

The operation of this structure will be described with reference to FIG. 3. The length from the support pin 5 to the pin 17 which is the connecting point between the backrest lower member 8 and the backrest upper member 9 is (R1),
The length up to 16 is (R3), the length from the shaft 14 to the lower end mounting position of the biasing spring 15 is (R2), and R1>R3> R2.

When a load is applied to the seat plate 4, the seat plate 4 and the like, as indicated by the alternate long and short dash line in FIG. 1, tilt backward.

At this time, the seat plate 4 moves around the support pin 5 ((θ
1) When tilted backward, the amount of lowering of the pin 17 (L1)
Is approximately smaller than θ1 × R1 (because θ1 × R1 is an arc length, the position of the pin 17 is largely above the support pin 5, and the descending amount is the vertical length of the arc length). This is because it is a directional component).

On the other hand, the 16 pressing pieces descend by approximately θ1 × R3,
Correspondingly, the link 13 extending rearward in the substantially horizontal direction is θ2.
Since it rotates downward by the angle of, the descending amount (L2) of the rear part of the link 13 (where the lower end of the bias spring is attached) is approximately θ2 x R2.
Becomes

Since the pressing piece 16 presses the front and rear halfway portion of the link 13 downward, since the length (R2) of the link 13 is shorter than R1 and R3, generally θ2 becomes much larger than θ1.
It is very easy to set the length relationship of each part so that the descending amount (L2) of the rear part of the link 13 (the attachment point of the lower end of the biasing spring) is larger than the descending amount (L1) of the 17 pins. .

Moreover, since both the angles θ1 and θ2, and hence the descending amounts L1 and L2 can be considered to be proportional to the lightness of the weight of the person on the seat plate 4, only the downward load (body weight) is applied to the seat plate 4. In this state, the initial deflection amount (L1-L2)> 0 can be applied to the biasing spring 15 in proportion to the load (body weight).

In other words, the biasing spring 15 is given an initial resistance force of a value obtained by multiplying the spring constant of the spring constant by the initial deflection amount (L1-L2). It means that the initial elastic force as a cushion proportional to the value is applied.

Since a person having a light weight leans less on the backrest member 9, leaning on the backrest member 9 having a small initial elastic force applied to the backrest member 9 makes it possible to soften the cushion of the backrest member. Can give the feeling of sitting.

On the other hand, when a person with a heavy weight sits down, the initial elastic force applied to the backrest member 9 also becomes large, so that the backrest member 9 is increased.
Even if a heavy leaning load is applied to the cushion, the cushion does not tilt backward greatly and the cushion does not feel too soft.

As described above, since the cushioning property for resisting the rearward inclination of the backrest member is automatically adjusted so as to be proportional to the weight of the person sitting on the seat plate 4 of the chair of the present invention, it is automatically executed. Therefore, it is possible to provide a chair having optimum cushioning properties regardless of the weight of a person.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a side sectional view of a chair, FIG. 2 is a structural view of essential parts seen from the back of the chair, and FIG. 3 is an explanatory view. 1 ... Chair, 2 ... Leg support, 3 ... Support base, 4 ... Seat plate, 5 ... Support pin, 6 ... Spring means, 7 ... Back support frame, 8 ... Back support member , 9 ... back support member, 10 ... upper frame, 11 ... bracket, 12 ... connecting rod, 13 ... link,
14 …… Axis, 15 …… Biasing spring, 16 …… Pressing piece, 17 …… Pin.

Claims (1)

[Claims] 1. A front part of a seat plate is rotatably supported by a front part of a support base of a chair so as to be vertically rotatable, and a backrest member which tilts forward and backward integrally with the seat plate is provided upright on a rear part of the seat plate. A rear portion of a link that connects the upper back member to the lower back member so that the upper back member can be tilted back and forth, and has a base end pivotally attached to a support base and extending rearward at a rear portion from a pivot point of the seat plate. An urging spring is mounted between the backrest member and the backrest member, and in order to increase the amount of bending of the urging spring in response to the rearward tilting of the seat plate, the pressing piece at the rear part of the seat plate is used to move the link forward and backward. A tilting device for a chair, characterized in that it has a structure for pressing the portion so as to rotate downward.