Chairs and seats – Movable back – Tiltable
Reexamination Certificate
1999-11-17
2001-08-28
Barfield, Anthony D. (Department: 3624)
Chairs and seats
Movable back
Tiltable
C297S362140, C297S374000
Reexamination Certificate
active
06279995
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reclining device applied to a seat of a vehicle, such as an automobile, or of a piece of furniture, and more particularly to an improvement of locking means of the reclining device.
A seat of an automobile or the like is provided with a reclining device for adjusting the in clination of seat back. There are various types of conventional reclining devices. Described in U.S. Pat. No. 5,778,733 is one such reclining device that uses a linear mechanical lock system, combining a lead screw and a nut.
The reclining device using the linear mechanical lock system comprises a housing fixed to a seat cushion of a seat or the like, the lead screw connected to a seat back of the seat, etc. Further, the nut is rotatably stored in the housing. The nut is in mesh with the lead screw. In this prior art example, the nut is unlocked in changing the angle (reclining angle) of the seat back. If the inclination of the seat back is changed in this unlock state, the lead screw moves in its axial direction with the change of the seat back angle, and the nut rotates in the housing. The seat back can be locked by locking the nut after adjusting the reclining angle.
In the prior art example, the lead angle of the lead screw must be made wider than that of an ordinary screw, in order to allow the nut to rotate as the lead screw moves in the axial direction after the nut is unlocked. In order to reduce the resistance of rolling friction of the nut on the lead screw, moreover, a bearing member should be interposed between the housing and the nut. Further, a lock system is needed to stop the rotation of the nut. In consequence, the conventional reclining device has a complicated construction and requires use of a lot of components, thus entailing an increase in cost.
BRIEF SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a reclining device having a simple construction and requiring use of fewer components and therefore lower cost.
In order to achieve the above object, according to the present invention, there is provided a reclining device for fixing a seat back of a seat at a desired angle, comprising: a housing fixed to a seat cushion of the seat or the seat back; a shaft connected to the seat back or the seat cushion and formed having a plurality of recesses extending in the circumferential direction thereof and arranged in the axial direction thereof; a locking member having projections capable of individually engaging the recesses of the shaft and movable between a lock position in which the projections engage the recesses and an unlock position in which the projections are disengaged from the recesses; a cam member capable of reciprocating between a first position in which the cam member keeps the locking member in the lock position and a second position in which the cam member moves the locking member toward the unlock position; urging means for urging the locking member toward the lock position; and an operating member capable of moving the cam member to the second position.
In the reclining device of the invention constructed in this manner, the locking member moves to the unlock position when the cam member is moved to the second position by means of the operating member. As this is done, the projections of the locking member are disengaged from the recesses of the shaft. Thereupon, the shaft and the locking member are disengaged from each other. Thus, the shaft is allowed to move with respect to the housing, so that the angle (reclining angle) of the seat back can be adjusted.
If the operating force on the operating member is removed after the angle of the seat back is adjusted, the cam member is restored to the first position, and the locking member returns to the lock position. As the projections of the locking member engage the recesses of the shaft in this manner, the shaft is fixed to the housing.
According to the invention, there may be provided a high-strength linear mechanical lock, which can securely lock the seat back despite its simple construction and fewer components. In the reclining device of the invention, the recesses are arranged in the circumferential of the shaft. If a load acts on the shaft to twist it, therefore, the device cannot be disengaged. Further, the engagement between the recesses of the shaft and the projections of the locking member ensures reliable locking, so that there is no possibility of slippage between the shaft and the locking member.
Preferably, according to the invention, the recesses of the shaft constitute a helical thread groove in the outer peripheral surface of the shaft, and the projections of the locking member are thread ridges arranged at pitches corresponding to the thread groove. With the thread groove of the shaft and the thread ridges of the locking member thus engaged with one another, shearing strength between thread groove and the thread ridges can be a maximum strength of this device when the shaft and the locking member are locked. In designing the reclining device, therefore, the maximum strength of the device can be set with ease, thus ensuring efficient designing.
Preferably, moreover, the cam member is rockable around a pivot on the housing, and the locking member has a cam receiving face, adapted to come into contact with the cam member to hold the locking member in the lock position when the cam member is rocked to the first position, and an engaging portion, adapted to come into contact with the cam member to move the locking member to the unlock position when the cam member is rocked to the second position.
Preferably, furthermore, the locking member is composed of a pair of split nut pieces situated on either side of the shaft and rockable toward or away from each other, and the cam member includes frame portions, adapted to restrict the split nut pieces lest the nut pieces separate from each other when closed, and a wedge portion, adapted to wedge into the gap between the nut pieces to separate the same when the cam member is rocked from the first position to the second position.
Preferably, moreover, the cam member can reciprocate in the axial direction of the shaft with respect to the housing, and the locking member is movable in the diametrical direction of the shaft and includes a cam receiving face, adapted to be pressed by the cam member to hold the locking member in the lock position when the cam member is in the first position, and an engaging portion, adapted to come into contact with the cam member to move the locking member to the unlock position when the cam member is moved to the second position. With this arrangement, a high-strength linear mechanical lock can be obtained that has a simple construction and requires use of fewer components, thus ensuring lower cost and reduced weight.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 4685735 (1987-08-01), McFalls et al.
patent: 4880084 (1989-11-01), Tanaka et al.
patent: 5295730 (1994-03-01), Rees
patent: 5778733 (1998-07-01), Stringer
patent: 5997089 (1999-12-01), Kawasaki
Nakamura Takeshi
Ohki Osamu
Barfield Anthony D.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
NHK Spring Co. Ltd.
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