Chairs and seats – Movable back – Tiltable
Reexamination Certificate
2001-07-13
2003-05-20
Nelson, Jr., Milton (Department: 3636)
Chairs and seats
Movable back
Tiltable
C297S366000, C297S364000, C297S374000, C403S097000
Reexamination Certificate
active
06565156
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an angle adjusting device for adjusting a tilting angle of a backrest portion of a legless chair or a foldable bed, for example.
BACKGROUND ART
In an easy-to-carry foldable bed folded into three by folding down the backrest portion and footrest portion over the seat portion, for example, each of the frames respectively forming the backrest portion and footrest portion is coupled to the frame of the seat portion through an angle adjusting device, whereby it is possible to adjust tilting angles of the backrest portion and footrest portion with respect to the seat portion.
As is disclosed in Japanese Utility Model Publication No. 59-20118 filed by the inventors of the present application, for example, such an angle adjusting device is provided with coupling portions each coupled to the respective tip end portions of the two frames respectively forming, for example, the seat portion and backrest portion.
The coupling portion at the seat portion side commonly used as the stationary side is provided with a pair of disc portions with their thickness direction directed to the width direction of the foldable bed, and the coupling portion at the backrest portion side commonly used as the movable side coaxially supports a spur ratchet gear placed with its thickness direction directed to the width direction of the foldable bed.
Also, a hook of ratchet supported somewhere between the pair of disc portions is allowed to move around the axis in the width direction of the foldable bed, and pushed by a spring in a direction such that the ratchet engages with the gear teeth of a ratchet gear.
Each of the gear teeth has a tapered surface such that presses the ratchet against the spring in association with a rotation of the ratchet gear when the backrest portion is folded, so that the engagement with the ratchet can be released. However, once the ratchet reaches the adjacent gear tooth, the ratchet constantly pushed by the spring engages with that gear tooth again. Also, each of the gear teeth has a surface of a shape such that maintains the engagement with the ratchet in association with a rotation of the ratchet gear when the backrest portion is unfolded.
Hence, a tilting angle of the backrest portion can be changed as one desires in the folding direction, whereas the tilting angle of the backrest portion in the unfolding direction with respect to the seat portion can be changed step by step in accordance with the gear teeth because the ratchet is locked.
Here, the angle adjusting device as discussed above is provided with releasing mechanism that releases the engagement between the ratchet and gear teeth by pressing the ratchet against the spring when a tilting angle of the backrest portion in the folding direction reaches a predetermined angle. The releasing mechanism returns the ratchet and gear teeth in the initial engagement state when the backrest portion is rotated to the maximum unfolded position after the engagement is released.
However, the conventional angle adjusting device as discussed above maintains the backrest portion, for example, of the foldable bed, at a predetermined angle by engaging the ratchet with a single gear tooth of the ratchet gear, which raises a problem that, when one lies down on the foldable bed, all the applied load concentrates onto the single gear tooth and ratchet.
The above problem may be solved by upsizing the gear teeth and ratchet. However, this solution causes inconveniences such that the entire angle adjusting device becomes so large that it impairs one's lying comfort, etc. Also, when the gear teeth alone are upsized while maintaining the size of the entire angle adjusting device intact, the total number of the teeth is reduced, which raises another problem that an adjustable angle per step becomes larger.
It may be possible to increase hardness of the gear teeth and ratchet without changing their respective sizes by subjecting the same to carburization or making the same out of materials having higher hardness. However, this increases the manufacturing costs, which poses another problem.
The present invention is devised to solve the above problems and has an object to provide a rigid angle adjusting r, which can be assembled at a low cost without increasing the size by providing a plurality of engaging portions to a pair of rotors that relatively rotate around the axis of rotation on their respective counter surfaces opposing in a direction along the axis of rotation, and pushing the rotors in an opposing direction by a spring so as to maintain the engagement of the engaging portions on the rotors.
SUMMARY OF THE INVENTION
An angle adjusting device of the present invention is an angle adjusting device capable of adjusting a relative rotating position of a pair of rotors coupled through an axis of rotation step by step, the device including: a plurality of engaging portions provided on surfaces of the pair of rotors opposing in a direction along the axis of rotation; and a spring for pushing the pair of rotors in an opposing direction.
According to the invention, it is arranged such that a plurality of engaging portions are provided to a pair of rotors that relatively rotate around the axis of rotation on their respective counter surfaces opposing in a direction along the axis of rotation, and a spring for pushing the rotors in an opposing direction is provided to maintain the engagement between the rotors. Consequently, it is possible to readily assemble a rigid and compact angle adjusting device that develops a quite large engaging strength by engaging at the plurality of engaging portions.
The angle adjusting device of the present invention can be attached to a foldable bed, a legless chair, etc. as discussed above through coupling portions that will be described below. It should be appreciated, however, that the application is not limited to the foldable bed, legless chair, etc., and the angle adjusting device can be employed in other products that need angle adjustment. Also, the angle adjusting device does not have to be attached to the foldable bed, legless chair, etc. through the coupling portion, and can be attached to the same at the rotors either directly or indirectly.
Another angle adjusting device of the present invention is characterized by further including a releasing body placed concentrically somewhere between the pair of rotors, wherein the releasing body allows engagement between the pair of rotors when placed at a first rotating position with respect to either one of the pair of rotors, and releases the engagement by moving the pair of rotors apart from each other when placed at a second rotating position.
According to the invention, it is arranged such that a releasing body is placed concentrically somewhere between the pair of rotors, and the releasing body allows engagement between the pair of rotors when placed at the first rotating position with respect to either one of the pair of rotors, and releases the engagement by moving the pair of rotors apart from each other when placed at the second rotating position. Consequently, it is possible to provide releasing mechanism for the engagement of the angle adjusting device as discussed above by a simple arrangement.
Still another angle adjusting device of the present invention is characterized in that: one of the either one of the rotors and the releasing body is provided with a convex portion on a counter surface opposing the other; and the other is provided with, on a counter surface opposing a counterpart, a concave portion that engages with the convex portion when the releasing body is placed at the first rotating position, the convex portion moving one of the either one of the rotors and the releasing body apart from the other by touching the counter surface of the other except for the concave portion when the releasing body is placed at the second rotating position.
According to the invention, it is arranged such that one of the either one of the rotors and the releasing body is provided with a convex portion on a coun
Yamashita Tadanobu
Yamashita Yoshinobu
Burns Doane , Swecker, Mathis LLP
Garrett Erika
Jr. Milton Nelson
Koyo Giken Co., Ltd.
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