Rotary positioning device for armrest assembly

A rotary positioning device for an armrest includes a positioning member, a base, a sliding member, and a detent member. The positioning member includes a plurality of first engaging recesses formed at a side edge thereof. The base is rotatably connected to the positioning member. The sliding member is slidably arranged in base and is selectively switchable between a locked position and an unlocked position. The detent member is movably arranged in the base and is selectively engaged with one of the plurality of first engaging recesses to correspond to the locked position or the unlocked position of the sliding member.

BACKGROUND OF THE INVENTION

The present invention relates to a rotary positioning device and, particularly, to a rotary positioning device applied in an armrest assembly.

A pair of armrests is associated with chairs to provide support for forearms of users while working despite the differences in sizes, shapes and preferences of users. This is important for individuals having desk jobs where persons may stay seated for long periods of time and where different users use the same sized chair. It is also important for users that are different in size to be able to adjust the armrest to a lateral position that is comfortable for them. In this regard it is common for the armrest to be selectively rotatable in relation to a support member about a vertical axis.

However, the above arrangement of the armrest and the support is not stable. The armrest is easily rotated in relation to the support member due to an inadvertent force from the forearm of the user.

BRIEF SUMMARY OF THE INVENTION

A rotary positioning device includes a positioning member, a base, a sliding member, a detent member, and an elastic member.

The positioning member is adapted to be mounted on a support member. The positioning member has a first side and a second side opposite to the first side. The positioning member includes a plurality of first engaging recesses formed at the first side in a circumferential direction of the positioning member. Two adjacent first engaging recesses of the plurality of first engaging recesses are separated from each other at an angle less than 60 degrees in the circumferential direction.

The base is rotatably connected to the positioning member. The base includes a rotary recess, a sliding recess, a connection recess interconnected between the rotary recess and the sliding recess, and a guiding portion protruded from a bottom face of the sliding recess. The rotary recess rotatably receives the positioning member. The sliding recess includes a first connecting portion protruded from an inner face of the sliding recess.

The sliding member is slidably arranged in the sliding recess of the base and is selectively switchable between a locked position and an unlocked position. The sliding member includes a side face and a receiving recess depressedly formed at the side face. The receiving recess has a depth in relation to the side face. The sliding member has a proximal end and a distal end opposite to the proximal end. The distal end is provided with a second connecting portion. The sliding member further includes a guiding recess extending from the proximal end to the distal end. The guiding recess is slidably engaged with the guiding portion of the base.

The detent member is movably arranged in the connection recess of the base. The detent member is selectively engaged with one of the plurality of first engaging recesses of the positioning member or is received in the receiving recess of the sliding member. The detent member has an outer diameter greater than the depth of the receiving recess.

The elastic member has a first end connected to the first connecting portion of the sliding recess, and a second end connected to the second connecting portion of the distal end of the sliding member.

When the sliding member is in the locked position, the detent member is engaged with one of the plurality of first engaging recesses of the positioning member and is abutted against the side face of the sliding member. The base is unable to rotate in relation to the positioning member.

When the sliding member is in the unlocked position, the detent member is moved in relation to the connection recess of the base to be disengaged from one of the plurality of first engaging recesses of the positioning member and is received in the receiving recess of the sliding member. The distal end of the sliding member compresses against the elastic member. The base is able to rotate in relation to the positioning member.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-6show a rotary positioning device according to the present invention. The rotary positioning device includes a positioning member10, a base20rotatably connected to positioning member10, a sliding member30slidably arranged in base20, a detent member40movably arranged in base20, an elastic member50located between base20and sliding member30, a first housing60receiving base20, and a second housing70detachably mounted on first housing60.

Positioning member10is adapted to be mounted on a support member (not shown). Positioning member10includes a first side11, a second side12opposite to first side11, a plurality of first engaging recesses13formed at first side11in a circumferential direction of positioning member10, and an engaging portion14radially protruded from second side12. Two adjacent first engaging recesses13may be separated from each other at an angle less than 60 degrees in the circumferential direction. However, depending on the state, the angle formed between two adjacent first engaging recesses13also can be less than 45 degrees, 30 degrees, etc. Plurality of first engaging recesses13and engaging portion14may be integrally formed at first and second sides11and12, respectively.

Base20includes a rotary recess21, a sliding recess22, a connection recess23interconnected between rotary recess21and sliding recess22along a length direction, a guiding portion24protruded from a bottom face of sliding recess22along a height direction and extending along a width direction, and a plurality of second engaging recesses25formed on an inner wall of rotary recess21in a circumferential direction of rotary recess21. Rotary recess21rotatably received positioning member10. Sliding recess22slidably receives sliding member30. Rotary recess21includes a first connecting portion221protruded from an inner face of sliding recess22along the width direction. One of plurality of second engaging recesses25is selectively engaged with engaging portion14.

Sliding member30is slidably arranged in sliding recess22along the width direction and is selectively switchable between a locked position and an unlocked position. Sliding member30includes a side face31, a receiving recess32depressedly formed at side face31along the length direction and extending along the width direction, a proximal end33, a distal end34opposite to proximal end33, a guiding recess35formed on a bottom face of sliding member30and extending from proximal end33to distal end34along the width direction, and a plurality of positioning portions36protruded from a top face of sliding member30along the height direction and equally spaced from each other along the length direction. Side face31and receiving recess32can be faced to connection recess23. Receiving recess32has a depth D32in relation to side face31along the length direction. Distal end34is provided with a second connecting portion341on an end face thereof. Guiding recess35does not penetrate through the top face of sliding member30and is slidably engaged with guiding portion24along the width direction.

Detent member40is movably arranged in connection recess23along the length direction to be selectively engaged with one of plurality of first engaging recesses13or to be received in receiving recess32. Detent member40may be cylindrical and has an outer diameter D40greater than depth D32of receiving recess32.

Elastic member50having a first end connected to first connecting portion221of sliding recess22, and a second end connected to second connecting portion341of distal end34of sliding member30.

First housing60includes a through-hole61interconnected with rotary recess21, and a button62slidably mounted in first housing60along the width direction. Positioning member10protrudes out of first housing60via through-hole61to be mounted on the support member. Button62abuts against proximal end33of sliding member30.

Second housing70is threadedly mounted on first housing60. Base20is disposed between first and second housings60and70to form an armrest assembly to provide support for the forearm of a user. Second housing70includes a plurality of positioning recesses71selectively engaged with plurality of positioning portions36of sliding member30. Moreover, second housing70may be covered by soft materials.

When sliding member30is in the locked position, detent member40is engaged with one of plurality of first engaging recesses13of positioning member10and is received in connection recess23of base20. Detent member40is abutted against side face31of sliding member30. One of plurality of second engaging recesses25of base20is engaged with engaging portion14of positioning member10. Plurality of positioning recesses71of second housing70is engaged with plurality of positioning portions36of sliding member30. Thus, base20is unable to rotate in relation to positioning member10to provide a stable engagement therebetween.

The user can push button62, thereby button62slides in relation to first housing60along the width direction to abut against proximal end33of sliding member30to cause sliding member30switched from the locked position to the unlocked position. Distal end34of sliding member30compresses against elastic member50to cause elastic member50compressed between the inner face of sliding recess22and distal end34of sliding member30.

When sliding member30is in the unlocked position, detent member40is moved in relation to connection recess23of base20along the length direction to be disengaged from one of plurality of first engaging recesses13of positioning member10and is received in receiving recess32of sliding member30. Plurality of positioning portions36of sliding member30is disengaged from plurality of positioning recesses71of second housing70. Thus, base20is able to rotate in relation to positioning member10.

When the user stops pushing button62, sliding member30is automatically return from the unlocked position to the locked position under the elastic restoring force of elastic member50. Detent member40is engaged with another one of plurality of first engaging recesses13of positioning member10to achieve the angle adjustment of positioning member10and base20.