Fixing Structure for a Foot Ring of a Chair

Abstract

A fixing structure for a foot ring of a chair includes the foot ring having a hub with a central hole formed with internal threads on an inner surface thereof; and a bush being a cylindrical body having a tapered outer surface with external threads formed thereon. The bush has a shaft hole penetrating along a longitudinal axis of the bush, a groove penetrating through a wall of the bush, and at least one pad provided on an inner surface of the shaft hole of the bush. The bush is assembled with the hub by screwing the external threads of the bush with the internal threads of the hub. A supporting post penetrates through the shaft hole of the bush. When the bush rotates toward a first direction, the shaft hole is reduced to clamp and fix the supporting post, and when the bush rotates toward a second direction, the shaft hole is enlarged to release the clamping and fixing of the supporting post.

Claims

1. A structure for fixing a foot ring to a chair, comprising: a ring body, a hub arranged concentrically with the ring body, and a plurality of spokes radially arranged between an inner periphery of the ring body and an outer periphery of the hub, wherein the hub has a central hole formed with internal threads on an inner surface thereof; and a bush being a cylindrical body having a tapered outer surface with external threads formed thereon, wherein the bush has a shaft hole penetrating along a longitudinal axis of the bush, wherein two recesses are formed on the opposite sides of the inner surface of the shaft hole, the two recesses are respectively extending through the inner surface along the axial of the shaft hole, and two pads are respectively disposed on and protrude from the recesses, the two pads are softer and having a higher coefficient of friction compared to a coefficient of friction of the inner surface of the shaft hole, and a groove penetrating through a wall of the bush, wherein two opposite sidewalls of the groove have a width spaced apart from each other, and form an angle in a widthwise direction thereof, wherein the range of the angle is 5° to 8°, wherein the range of the width is 5 to 10 mm, and wherein the bush is assembled with the hub by screwing the external threads of the bush with the internal threads of the hub, a supporting post penetrates through the shaft hole of the bush, and when the bush rotates toward a first direction, the wall of the bush is restricted by the central hole and the inner diameter of the shaft hole is reduced to clamp and fix the supporting post, when the bush rotates toward a second direction, the wall of the bush restricted by the central hole is released to make the shaft hole enlarge to release the clamping and fixing of the supporting post, wherein the first direction and the second direction are opposite to each other.

2. The fixing structure of claim 1, wherein an outer edge of a large diameter end of the tapered bush is formed with a flange protruding radially outward.

3-7. (canceled)

8. The fixing structure of claim 1, wherein the pads are adhesively fixed on a bottom surface of the recesses.

9. The fixing structure of claim 1, wherein the two pads are made of silicone or rubber material.

10. The fixing structure of claim 1, wherein the supporting post is a pneumatic cylinder for providing a seat of the chair to be raised or lowered.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 illustrates a schematic perspective view of a foot ring according to an embodiment of the present invention, which is assembled on a supporting post of a chair;

[0021] FIG. 2 illustrates an exploded perspective view of an assembled relationship of the foot ring, the bush and the supporting post;

[0022] FIG. 3 illustrates an exploded perspective view of an assembled structure of the bush and the pads;

[0023] FIG. 4 illustrates a front view of the bush;

[0024] FIG. 5 illustrates a top view of the bush;

[0025] FIG. 6 illustrates a front sectional view showing the foot ring and the bush fixedly assembled with the supporting post;

[0026] FIG. 7 illustrates a top plan sectional view showing the foot ring and the bush fixedly assembled with the supporting post; and

[0027] FIG. 8 illustrates a top plan sectional view showing a state in which the foot ring and the bush are released from the supporting post.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0028] The following describes the implementation of the present invention in more detail with drawings and numerals, so that those skilled in the art can implement it after studying the present specification.

[0029] As shown in FIG. 1, the foot ring 1 of the present invention is assembled at an appropriate height position of a supporting post 3 of a chair, so that the feet of a user sitting on the chair can step thereon and feel comfortable. The fixing structure is to allow the foot ring 1 to be quickly, stably and firmly mounted on the supporting post 3. The chair is suitable for a chair having a single supporting post, such as an office chair and a high chair.

[0030] The supporting post 3 may be a rod generally used to support a chair, or may be a pneumatic cylinder used to support a seat of a chair and capable of controlling the seat to be raised or lowered in a vertical direction.

[0031] As shown in FIG. 2, the fixing structure of the foot ring for a chair provided in the present invention preferably comprises a foot ring 1 and a bush 2. The foot ring 1 can be made of any suitable material, for example, which is made of aluminum alloy material by casting. The foot ring 1 has a ring body 11 and a hub 12 arranged concentrically each other, and a plurality of spokes 13 are radially arranged between an inner periphery of the ring body 11 and an outer periphery of the hub 12. The spokes 13 connect the ring body 11 and the hub 12 together and maintain both at a concentric position. The hub 12 has a central hole 121, which is formed with internal threads 122 on an inner surface thereof by turning.

[0032] As shown in FIGS. 3 to 5, the bush 2 can be integrally formed by a plastic material, a composite material or any suitable material to be a cylindrical body having a tapered outer surface with external threads 21 formed thereon, so as to form the bush 2 with a shaft hole 20 penetrating along a longitudinal axis of the bush. An outer edge of the large diameter end of the tapered-shape bush 2 is formed with a flange 24 protruding radially outward. A groove 22 is formed to penetrate through a wall of the bush 2. Two opposite sidewalls of the groove have a width W spaced apart from each other, and form an angle θ in a widthwise direction thereof. The angle θ is preferably 5° to 8°, and the width W is preferably 5 mm to 10 mm. The groove 22 may provide the wall of the bush 2 to be elastically deformed in a radial direction, so as to elastically reduce or enlarge an inner diameter of the shaft hole 20. The angle θ may provide the opposite sidewalls of the groove 22 to be close to each other when the shaft hole 20 is reduced to a certain degree.

[0033] The width W of the groove 22 should be suitably set, so as to provide a sufficient contact area for obtaining an enough clamping force between an outer surface of the supporting post 3 and the inner surface of the shaft hole 20 when the supporting post 3 penetrates through the shaft hole 20. In other words, if the width W is too large, the inner surface area of the shaft hole 20 will decrease, and thus the contact area between the outer surface of the supporting post 3 and the inner surface of the shaft hole 20 will decrease, thereby reducing the frictional force of the contact surface of the inner surface of the shaft hole 20 with the outer surface of the supporting post 3. In contrast, if the width W is too small, although the inner surface area of the shaft hole 20 is relatively increased, an deformation amount of the bush 2 in the radial direction will be decreased due to the contact of the opposite sidewalls of the groove 22 with each other, and thereby decreasing the clamping force of the bush 2 on the supporting post 3. Therefore, the optimal width W of the groove 22 at an outer edge of the bush 2 is 5 mm to 10 mm.

[0034] In the preferred embodiment of the present invention, at least one pad 23 may be further provided on the inner surface of the shaft hole 20, and the at least one pad 23 may protrude from the inner surface of the shaft hole 20. The pad 23 is softer relative to the inner surface of the shaft hole 20 and has a high coefficient of friction. For example, the pad 23 may be made of silicone or rubber material. Preferably, recesses 201 may be formed on opposite sides of the inner surface of the shaft hole 20, and two pads 23 are respectively disposed in the recesses 201. For example, the pad 23 may be fixed on a bottom surface of the recess 201 with an adhesive; or the pad 23 may be pressed into the recess 201 in a tight fit manner.

[0035] The operation method of fixing the foot ring 1 to the supporting post 3 using the fixing structure is described below: The bush 2 is assembled with the hub 12 by spirally fitting the internal thread 122 with the external thread 21, so as to make the bush 2 penetrate into the central hole 121 along the longitudinal axis thereof. Since the bush 2 having a tapered outer surface is fitted with the central hole 121 having an uniform inner diameter, the wall of the bush 2 will be gradually restricted by the central hole 121 and radially deformed to shrink during a process of rotating the bush 2 toward a first direction (for example, clockwise) into the central hole, and thus to reduce the inner diameter of the shaft hole 20 until the flange 24 abuts against a lower edge of the hub 12. In contrast, when rotating the bush 2 toward a second direction (for example, counterclockwise), the wall of the bush 2 restricted by the central hole 121 will be gradually released and radially expanded while the bush 2 gradually rotates out of the central hole 121, and thus enlarge the inner diameter of the shaft hole 20.

[0036] Therefore, when assembling the foot ring 1 on the supporting post 3, the bush 2 should be rotated firstly and moved outward from the central hole 121 for enlarging the inner diameter of the shaft hole 20 to allow the supporting post 3 to penetrate through, and then insert the supporting post 3 into the shaft hole 20, and then rotate and move the bush 2 inward the central hole 121. As described above, the shaft hole 20 will be shrunk during the movement of the bush 2 into the shaft hole 20, and thus the inner diameter of the shaft hole 20 is decreased to clamp and fix the supporting post 3, as shown in FIGS. 6 to 7. In particular, since the soft pads 23 provided on the shaft hole 20 protrudes from the inner surface of the shaft hole 20, the pads 23 will be compressed to deform during the process of clamping the supporting post 3 with the shaft hole 20 of the bush, so that the supporting post 3 can be supported and clamped by the pads 23 with a higher friction coefficient. Similarly, when needing the adjustment of the foot ring 1 to other height positions, the bush 2 is rotated to release the clamping on the supporting post 3, as shown in FIG. 8, the foot ring 1 can be moved upward and downward along the supporting post 3, and then the bush 2 is rotated toward a reverse direction to fix it on the supporting post 3 after a desired height position is reached.

[0037] The above description is only for explaining the preferred embodiments of the present invention, and is not intended to limit the present invention. Therefore, any form of the changes should be included in the scope of the invention as claimed.