JPH06121722A - Leg device for chair - Google Patents

Abstract

PURPOSE:To improve durability without forming a bottom plate thicker at a support hole in a chair having a leg body provided with the support hole opened up at a central part of a plan vie moulded of a synthetic resin, and a leg pole such as a gas spring supported by a bottom plate of the support hole CONSTITUTION:A cushioning body 13 of rubber or the like is inserted between an upper surface of a bottom plate 6b at a support hole 6 and a lower part of a leg pole 11 for supporting the leg body 11 through the cushioning body 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leg device in a chair for office work.

[0002]

2. Description of the Related Art A leg device for an office chair is generally a leg body having a plurality of leg rods that extend radially in a plan view, and supports a pedestal such as a gas spring so as not to be tilted. A seat is attached to the top of the pillar. In order to improve the external appearance and simplify the manufacturing process, the legs are integrally molded with synthetic resin. In that case, conventionally, a support hole with an upward opening having a cylindrical portion protruding upward is formed in the substantially central portion of the leg body, and the lower end portion of the pedestal is directly contacted with the upper surface of the bottom plate in the support hole. The bottom load of the support hole directly supports the downward load acting on the pedestal.

[0003]

[Problems to be Solved by the Invention] However, in this way,
In the configuration in which the lower end of the pedestal is brought into direct contact with the upper surface of the bottom plate in the support hole, each time a person sits on the chair, the weight of the person directly acts on the bottom plate of the support hole as an impact force. Therefore, there is a problem that the durability of the bottom plate in the support hole is low.

To solve this problem, for example, the actual exploitation sho 63-
As described in Japanese Patent No. 91048, it is considered that the thickness of the bottom plate in the support hole may be increased. However, in the case of integrally molding a leg body by an injection molding method or a reaction molding method using a pair of molds, in order to make the resin filled in the mold cavity harden in an even state,
Since there is an appropriate value for the thickness of each part of the leg, if the thickness of the bottom plate in the support hole is increased, the way the legs solidify becomes uneven and the strain due to the difference in shrinkage will occur. Another problem that may occur will occur.

An object of the present invention is to improve the durability of the legs without causing molding problems.

[0006]

In order to achieve this object, according to the present invention, a leg having an upward opening support hole into which a pedestal for supporting a seat is fitted is integrally molded with a synthetic resin, and the support is provided. In a chair in which the bottom plate of the hole supports the lower end of the pedestal, an elastic cushioning body is interposed between the upper surface of the bottom plate and the lower end of the pedestal in the support hole. .

[0007]

According to this structure, even if a large downward load is applied to the pedestal by a person sitting on a chair, the cushioning member elastically deforms to provide a large cushioning effect on the bottom plate of the support hole. The impact force can be prevented or reduced. Therefore, according to the present invention, the impact resistance can be improved without increasing the thickness of the bottom plate in the support hole, and thus the durability of the leg body does not occur without causing a problem such as the occurrence of strain during molding. Has the effect of improving

[0008]

Embodiments of the present invention will now be described with reference to the drawings. 1 to 4 show a first embodiment, and a chair denoted by reference numeral 1 in FIG. 3 includes a seat body 2, a backrest 3, and a leg device 4. The leg device 4 is a synthetic resin leg body 5 having a plurality of leg rods 5a extending radially in a plan view.
A supporting hole 6 having a cylindrical portion 6a protruding upward and a bottom plate 6b is formed in a substantially central portion of the leg body 5, and a bush 7 fitted to the cylindrical portion 6a is interposed therebetween. A gas spring 8 as an example of a pedestal is held so as not to fall down.
A caster 9 is provided at the tip of each leg rod 5a. Moreover, the bush 7 is formed in a split shape.

The gas spring 8 comprises a cylinder 10 and a downward piston rod 11 fitted therein. The upper end of the cylinder 10 is fixed to the seat body 2, while the lower end of the piston rod 11 is formed to have a small diameter. This small diameter part 1
The washer 12 is inserted into 1a so that it cannot be pulled out upward, and N
A cushioning body 13 formed of a rubber such as BR or urethane rubber or an elastic material such as a soft synthetic resin in a bush shape is fitted from below, so that the cushioning body 13 is provided between the lower surface of the washer 12 and the upper surface of the bottom plate 6b. Insert. Cylinder portion 13a of the buffer body 13
Is inserted into a hole 14 formed in the bottom plate 6b.

Small diameter portion 11a of the piston rod 11
A stopper 15 such as a snap ring or a split pin is locked to the downward protruding portion in order to prevent the piston rod 11 from slipping upward. An operating pin 16 projects from the upper end of the cylinder 10. When the operating pin 16 is pressed to unlock the piston rod 11, the seat body 2 can be moved up and down.

The leg rod 5a of the leg 5 is formed in a hollow shape with a downward opening, and a large number of ribs 17 are formed to improve the strength. With the above configuration, when a person sits on the chair 1, a large downward dynamic load acts on the gas spring 8, and this is supported by the bottom plate 6b of the support hole 6. In that case, the dynamic load acting on the gas spring 8 will be supported by the bottom plate 6b of the support hole 6 via the cushion 13, and the cushion 13 due to elastic deformation of the cushion 13 will support the support hole 6. Since a large impact force can be prevented or reduced from acting on the bottom plate 6b, the durability thereof can be improved without increasing the thickness of the bottom plate 6b.

On the other hand, in the case of integrally molding the leg body 5 by an injection molding method or a reaction molding method using a pair of molds, in order for the resin filled in the mold cavity to be uniformly hardened,
There is an appropriate value for the thickness of each portion of the leg body 5, and if it deviates from the appropriate value, strain tends to occur due to the difference in shrinkage when the resin hardens. However, according to the present invention, since the durability of the bottom plate 6b can be improved without changing the thickness of the bottom plate 6b in the support hole 6, the leg body 5 is distorted due to the improved durability of the bottom plate 6b. Can be prevented.

As in this embodiment, the shock absorber 13 is attached to the tubular portion 1.
When 3a is formed and fitted into the hole 14 of the bottom plate 6b,
When a person sitting on the chair 1 horizontally moves the body to exert a lateral force on the piston rod 11, the lateral movement of the piston rod 11 is buffered by the tubular portion 13 a of the buffer body 13. Along with the fact that the lateral movement of the rod 11 is reduced by the friction of the collar portion of the shock absorber 13, the lower end portion of the piston rod 11 may be grasped and fixed to the bottom plate 6b of the support hole 6 as if it were fixed. Can be held at.

Therefore, there is an advantage that the durability of the bottom plate 6b can be further improved and the durability of the gas spring 8 can be improved. FIG. 5 shows the buffer 13 formed in a plate ring shape having an appropriate thickness.
FIG. 6 shows the buffer 13 formed in a ball shape. Further, FIG. 7 shows a shock absorber formed in an O-ring, and in this embodiment, a support metal fitting 18 including a collar 18a and a cylinder portion 18b is fitted on the small diameter portion 11a of the piston rod 11. , The cylindrical portion 18b of the support metal fitting 18 to the bottom plate 6b
It is fitted in the hole 14 of the.

FIG. 8 shows a buffer body 13 formed in a washer shape. In the embodiment of FIG. 8, a support fitting 19 including a collar 19a and a tubular portion 19b is fitted on the lower end of the piston rod 11, and the tubular portion 19 of the support fitting 19 is fitted.
b and a downwardly exposed portion of the piston rod 11 are respectively formed with male screws, while one nut 20 is provided with a support fitting 19
Female threaded holes 20a, 2 of different sizes which are screwed into the male thread of the cylinder portion 19b and the male thread of the piston rod 11.
No. 0b is bored, and the nut 20 is screwed into the tubular portion 19b of the support fitting 19 and the piston rod 11 at the same time, so that the piston rod 11 is held so as not to be pulled out in the up and down directions.

In the embodiment shown in FIGS. 1 to 6, when the shock absorber 13 is fitted on the piston rod 11 against its elasticity, the shock absorber 13 and the washer 12 are attached to the piston rod 11.
Since it can be held so as not to fall off, there is an advantage that the work can be performed extremely easily when the piston rod 11 is locked to the bottom plate 6b.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a leg device according to a first embodiment.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view of a chair.

FIG. 4 is a bottom view of the leg.

FIG. 5 is another example view of a buffer body.

FIG. 6 is a view showing another example of the buffer body.

FIG. 7 is a diagram showing another example of the buffer body.

FIG. 8 is a view showing another example of the buffer body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chair 4 Leg device 5 Leg body 6 Support hole 6b Bottom plate 8 Gas spring as an example of a pillar 12 Washer 13 Buffer body

Claims (1)

[Claims] 1. A leg body having a support hole with an upward opening into which a pedestal for supporting a seat body is fitted is integrally molded of synthetic resin, and a bottom plate of the support hole supports a lower end portion of the pedestal. The leg device in a chair, wherein a cushioning member made of an elastic material is inserted between the upper surface of the bottom plate and the lower end portion of the pedestal in the support hole.