GB2400024A

GB2400024A - Adjusting device for a backrest cushion

Info

Publication number: GB2400024A
Application number: GB0307571A
Authority: GB
Inventors: Yu-Shan Lai
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-04-02
Filing date: 2003-04-02
Publication date: 2004-10-06
Anticipated expiration: 2023-04-02
Also published as: DE20306509U1; GB0307571D0; GB2400024B

Abstract

An adjusting device of a backrest cushion (1) includes a housing (21), a threaded rod (23), a locking screw member (23), a top cover (24), and a restoring member (3). Thus, when the locking screw member is moved to the upper dead point or lower dead point, the screw bore (221) of the locking screw member is entirely detached from the threaded section (231) of the threaded rod, so that rotation of the threaded rod idles and the locking screw member is disposed at a stationary state, thereby preventing the screw bore and the threaded section from being worn out due to successive rotation of the threaded rod.

Description

ADJUSTING DEVICE FOR BACKREST CUSHION

The present invention relates to an adjusting device for a backrest cushion, and more particularly to an adjusting device:for a backrest cushion of a chair, wherein the parts of the adjusting device will not be broken or worn out due to the excessive or improperly applied force, thereby increasing the lifetime of the adjusting device.

A conventional adjusting device in accordance with the prior art shown in Fig. 6 is used to adjust the tension of the connecting wire 52 of the backrest cushion (not shown) of a chair and comprises a housing 50, a threaded o rod 51 rotatably mounted on the housing 50 and formed with a threaded section l0 extended through the whole length of the threaded rod 51, and a screw member 53 slidably mounted in the housing 50 and engaged with the threaded section 510 of the threaded rod 51. The connecting wire 52 has a first end secured to the backrest cushion and a second end passed through the housing 50 and secured to the screw member 53. In operation, the screw member 53 is engaged with the threaded section 510 of the threaded rod 51, so that when the threaded rod 51 is rotated, the screw member 53 is driven by rotation of the threaded rod 51 to displace in a linear manner, so as to stretch or loosen the connecting wire 52, thereby deforming and changing the curvature of the backrest cushion of the chair, so as to fit the user's practical requirement.

However, when the screw member 53 is moved to the leftmost position (the upper dead point) or the rightmost position (the lower dead point), the screw member 53 is stopped by the wall of the housing 50, so that further rotation of the threaded rod will drive the screw member 53 to press the wall of the housing 50 excessively, thereby easily wearing or breaking the teeth of the screw member 53 and the threaded section 5 l 0 of the threaded rod 51, and thereby decreasing the lifetime of the conventional adjusting device.

The primary objective of the present invention is to provide an adjusting device for a backrest cushion, wherein the parts of the adjusting device will not be broken or worn out due to the excessive or improperly applied force, thereby increasing the lifetime of the adjusting device.

lo Another objective of the present invention is to provide an adjusting device for a backrest cushion, wherein when the locking screw member is moved to the upper dead point or the lower dead point, the screw bore of the locking screw member is entirely detached from the threaded section of the threaded rod, so that rotation ofthe threaded rod will idle and the locking screw member will be disposed at a stationary state, thereby preventing the screw bore of the locking screw member and the threaded section of the threaded rod from being broken or worn out due to successive rotation of the threaded rod.

In the drawings: Fig. l is an exploded perspective yiew of an adjusting device for a backrest cushion in accordance with the preferred embodiment of the present invention; Fig. 2 is a perspective assembly view of the adjusting device for a backrest cushion in accordance with the preferred embodiment of the present invention; Fig. 3 is a top plan cross-sectional assembly view of the adjusting device for a backrest cushion as shown in Fig. l; Fig. 4 is a schematic operational view of the adjusting device for a backrest cushion as shown in Fig. 3 in use; Fig. 4A is a schematic operational view of the adjusting device for a backrest cushion as shown in Fig. 4; lo Fig. 5 is a schematic operational view of the adjusting device for a backrest cushion as shown in Fig. 3 in use; Fig. SA is a schematic operational view of the adjusting device for a backrest cushion as shown in Fig. 5; and Fig. 6 is a top plan cross-sectional assembly view of a conventional adjusting device for a backrest cushion in accordance with the prior art.

Referring to the drawings and initially,to Figs. 1-3, an adjusting device 2 in accordance with the preferred embodiment of the present invention is used to adjust the tension of the connecting wire 11 of the backrest cushion 1 of a chair.

The adjusting device 2 comprises a housing 21, a threaded rod 23, a locking screw member 22, and a restoring member 3.

The housing 21 has a first end formed with closed wall and a second end formed with an open wall. The closed wall of the housing 21 is formed with an insertion hole 210 and a passage hole 212.

flee threaded rod 23 is rotatably mounted on the housing 21, and has a first stroke 230, a middle stroke and a second stroke 232. The middle stroke of the threaded rod 23 is formed with a threaded section 231. The threaded rod 23 has a first end formed with an insert 234 rotatably mounted in the insertion hole 2 i 0 of the housing 21. The threaded rod 23 has a second end formed with an enlarged flange 235.

The adjusting device 2 further comprises a top cover 24 secured on -the open wall of the housing 21 to position the threaded rod 23 on the housing 21. Preferably, the top cover 24 is formed with a receiving recess 240 to receive the enlarged flange 235 of the threaded rod 23, so that the threaded rod 23 is retained on the housing 21. Thus, the threaded rod 23 is rotatably mounted on the housing 21 without a linear movement.

The locking screw member 22 is slidably mounted in the housing 21, and has a side formed with a screw bore 221 meshing with the threaded section 231 of the threaded rod 23. Preferably, the screw bore 221 of the locking screw member 22 is substantially C-shaped. The connecting wire 11 has a first end secured to the backrest cushion 1 and a second end passed through the passage hole 212 of the housing 21 and secured to the locking screw member 22.

Preferably, the locking screw member 22 has a periphery formed with a positioning recess 222, and the second end of the connecting wire ll is provided with a positioning stud l l 0 secured in the positioning recess 222 of the locking screw member 22.

The restoring member 3 is mounted on the connecting wire l] and is urged between the closed wall of the housing 2l and the wall of the locking screw member 22.

In operation, the screw bore 221 of the locking screw member 22 meshes with the threaded section 231 of the threaded rod 23, so that when the threaded rod 23 is rotated on the housing 21, the locking screw member 22 is lo driven by rotation of the threaded rod 23 to displace in the housing 21 in a linear manner as shown in Fig.3, so as to stretch or loosen the connecting wire 11, thereby deforming and changing the curvature of the backrest cushion l of the chair, so as to fit the user's practical requirement.

When the locking screw member 22 is moved in the housing 21 to the first position (the upper dead point) as shown in Fig. 4, the screw bore 221 of the locking screw member 22 is moved into the first stroke 230 of the threaded rod 23 and is entirely detached from the threaded section 231 of the threaded rod 23, so that rotation ofthe threaded rod 23 will idle and the locking screw member 22 will not driven to move, thereby preventing the screw bore 221 of the locking screw member 22 and the threaded section 231 of the threaded rod 23 from being broken or worn out due to successive rotation of the threaded rod 23. At this time, the restoring member 3 is closely urged between the closed wall of the housing 21 and the wall of the locking screw member 22.

On the contrary, when the threaded rod 23 is rotated in the reverse direction as shown in Fig.4A, the screw bore 221 ofthe locking screw member s 22 is engaged with the threaded section 231 of the threaded rod 23 again by the restoring force of the restoring member 3, so that rotation of the threaded rod 23 will drive the locking screw member 22 to move backward in the housing 21.

When the locking screw member 22 is moved in the housing 21 to the second position (the lower dead point) as shown in Fig. S. the screw bore 221 ofthe locking screw member 22 is moved into the second stroke 232 ofthe threaded rod 23 and is entirely detached from the threaded section 231 of the threaded rod 23, so that rotation ofthe threaded rod 23 will idle and the locking screw member 22 will not driven to move, thereby preventing the screw bore is 221 of the locking screw member 22 and the threaded section 231 of the threaded rod 23 from being broken or worn out due to successive rotation of the threaded rod 23. At this time, the backrest cushion 1 of the chair is stretched by the connecting wire 11 and the locking screw member 22 to have the greatest tension.

On the contrary, when the threaded rod 23 is rotated in the reverse direction as shown in Fig. SA, the screw bore 221 of the locking screw member 22 is engaged with the threaded section 231 of the threaded rod 23 again by the pulling force of the connecting wire 11, so that rotation of the threaded rod 23 will drive the locking screw member 22 to move forward in the housing 21.

Claims

1. An adjusting device of a backrest cushion, comprising a housing, a threaded rod, and a locking screw member, wherein: the housing has a first end formed with closed wall and a second end formed with an open wall; the threaded rod is rotatably mounted on the housing and has a first stroke, a middle stroke and a second stroke, the middle stroke of the threaded rod is formed with a threaded section; and the locking screw member is slidably mounted in the housing and has lo a side formed with a screw bore meshing with the threaded section of the threaded rod.

2. The adjusting device of a backrest cushion in accordance with claim 1, wherein the closed wall ofthe housing is formed with an insertion hole, and the threaded rod has a first end formed with an insert rotatably mounted in the insertion hole of the housing.

3. The adjusting device of a backrest cushion in accordance with claim 1, further comprising a top cover secured on the open wall ofthe housing to position the threaded rod on the housing.

4. The adjusting device of a backrest cushion in accordance with claim 3, wherein the threaded rod has a second end formed with an enlarged flanges and the top cover is formed with a receiving recess to receive the enlarged flange of the threaded rod, so that the threaded rod is retained on the housing.

5. The adjusting device of a backrest cushion in accordance with claim 1, wherein the screw bore of the locking screw member is substantially Cshaped.

6. The adjusting device of a backrest cushion in accordance with claim 1, further comprising a connecting wire having a first end secured to the backrest cushion and a second end secured to the locking screw member.

7. The adjusting device of a backrest cushion in accordance with l O claim 6, wherein the closed wall of the housing is formed with a passage hole for passage of the connecting wire.

8. The adjusting device of a backrest cushion in accordance with claim 6, wherein the locking screw member has a periphery formed with a positioning recess, and the second end of the connecting wire is provided with a positioning stud secured in the positioning recess of the locking screw member.

9. The adjusting device of a backrest cushion in accordance with claim 6, further comprising a restoring member mounted on the connecting wire and urged between the closed wall of the housing and the wall of the locking screw member.

10. The adjusting device of a backrest cushion in accordance with claim 1, wherein the locking screw member is moved in the housing to a first position where the screw bore of the locking screw member is moved into the first stroke of the threaded rod and is detached from the threaded section of the threaded roil, so that rotation of the threaded rod idles and the locking screw member is disposed at a stationary state.

11. The adjusting device of a backrest cushion in accordance with claim 10, further comprising a restoring member mounted on the locking screw member, wherein when the locking screw member is moved in the housing to the; first position, the restoring member is urged between the closed wall of the housing and the wall of the locking screw member.

ID

12. The adjusting device of a backrest cushion in accordance with claim 1, wherein the locking screw member is moved in the housing to a second position where the screw bore of the locking screw member is moved into the second stroke of the threaded rod and is detached from the threaded section of the threaded rod, so that rotation of the threaded rod idles and the locking screw member is disposed at a stationary state.

13. The adjusting device of a backrest cushion in accordance with claim 12, further comprising a connecting wire having a first end secured to the backrest cushion and a second end secured to the locking screw member, wherein when the locking screw member is moved in the housing to the second position, the connecting wire is stretched by the locking screw member.

14. An adjusting device of a backrest cushion, substantially as herein described with reference to any embodiment shown in the accompanying to drawings.