Chairs and seats – Movable back – Tiltable
Reexamination Certificate
1999-08-19
2001-07-31
Nelson, Jr., Milton (Department: 3624)
Chairs and seats
Movable back
Tiltable
C297S361100
Reexamination Certificate
active
06267443
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a reclining seat for a vehicle such as an automobile.
A manual type reclining seat comprises a buttock-supporting, seat and a backrest reclinably joined to the rear end of the seat. At the joint portion, there are provided a spiral spring for biasing the backrest to its upright position and a locking mechanism for locking the backrest at an adjusted position. A typical locking mechanism is a ratchet mechanism comprising a sector gear mounted on the backrest and a ratchet provided at an end of a control lever and engageable with teeth of the sector gear.
Since the backrest is locked in position by engaging the ratchet with teeth of the gear, its position is adjustable only stepwise, so that it is difficult to recline the backrest precisely to an ideal position at which the user is the least fatigued.
Also, the ratchet often meshes incompletely with a gear tooth. In such a case, the ratchet collides repeatedly against the gear, producing uncomfortable noise.
An object of this invention is to provide a reclining seat having a backrest which can be inclined to any desired position in a stepless manner without producing any awkward noise.
SUMMARY OF THE INVENTION
According to this invention, there is provided a reclining seat wherein a backrest is inclinably coupled to a seat cushion and is biased by an elastic member toward an upright position. A clutch is provided on a central axis about which the backrest pivots, and the clutch comprises a fixed ring mounted to the seat cushion, a rotary ring mounted to the backrest, a locking mechanism for frictionally locking the rotation of the rotary ring relative to the fixed ring by coming into frictional contact therewith, an unlocking mechanism for unlocking the locking mechanism, and a control mechanism for controlling the unlocking mechanism.
Here, the fixed ring may be one having a greater diameter than the rotary ring, or may be one having a smaller diameter.
With this arrangement, when the locking by the locking mechanism is released by controlling the unlocking mechanism through the control mechanism, the backrest is moved to an upright position under the resilient force of the resilient member. Also, by leaning the upper torso against the backrest, the backrest is inclined rearwardly. It is thus possible to adjust the inclination of the backrest to a desired degree. After the inclination adjustment, when the control mechanism is released and the weight is leaned against the backrest, the locking mechanism is activated the backrest is thus locked at the inclination adjusted position.
Since clutches are provided on both sides of the coupling portion of the seat cushion and the backrest, even if there is an uneven distribution of the load on the backrest, twisting of the backrest is prevented.
The locking mechanism may comprise cam grooves formed in the fixed ring on a circumferential surface thereof and which are the deepest at the circumferentially central portion thereof and gradually shallower toward both circumferential ends, a cylindrical surface formed on the rotary ring opposite the fixed ring, rolling elements received in the cam grooves such that when the rolling elements are in their neutral positions, i.e. positions at the circumferential center of each cam groove, a small radial gap is present between each rolling element and the cam groove, a cage mounted between the fixed ring and the rotary ring for retaining the rolling elements, and a friction mechanism provided between the cage and the rotary ring for transmitting the rotation of the rotary ring to the cage.
With such a locking mechanism, when the rotary ring tends to rotate relative to the fixed ring, the rolling elements come into frictional contact with the cam groove bottoms and the cylindrical surface, thus preventing rotation of the rotary ring in normal and reverse directions.
The locking mechanism may comprise arcuate cutouts formed on a small-diameter one of the opposed circumferential surfaces of the fixed and rotary rings, sprags each circumferentially pivotable about one of the cutouts, and adapted to come into frictional contact with the large-diameter circumferential surface when pivoted, a cage for retaining the sprags, and a friction mechanism provided between the cage and the rotary ring for transmitting the rotation of the rotary wing to the cage.
With this locking mechanism, when the rotary ring tends to rotate relative to the fixed ring, the sprags are inclined by the cage adapted to rotate together with the rotary ring, and brought into frictional engagement with the cylindrical surface, so that the rotary ring is locked. The backrest is thus retained in the inclination adjusted position.
The unlocking mechanism may comprise positioning recesses formed in one of opposed surfaces between the cage and the fixed ring, and positioning protrusions formed on the other of the opposed surfaces and each received in one of the positioning recesses with a clearing present in the rotating direction, the positioning protrusions being movable to engaged positions wherein the clearance disappear to position the cage relative to the fixed ring, thereby keeping the rolling elements in neutral positions at the circumferential center of each cam groove.
The operating device may comprise an operating member having a lever and provided axially opposite the cage so as to be rotatable relative to the cage, and cam device between the control member and the cage for pressing the cage when the control member rotates, thereby engaging the positioning protrusions in the positioning recesses.
In such unlocking mechanism and control mechanism, when the cage is pressed by rotating the control member through the operation of the lever, the positioning protrusions engage in the positioning recesses. By this engagement, the cage is positioned, so that the rolling elements or the sprags are held in the neutral position in which radial gaps are formed between them and the cylindrical surface. Thus, the rotary ring is now rotatable in both directions, so that the inclination of the backrest is adjustable.
Here, by providing the rotary ring with a frictional resistance imparting device, the means can absorb shaky motion of the backrest in the rotational direction. Thus, it is possible to obtain a reclining seat which is high in stability and comfortable.
Also, by using a spiral spring as an elastic member for imparting resilience to the backrest in the erecting direction, and by mounting the spiral spring in one of the fixed ring and the rotary ring that is smaller in diameter than the other, it is possible to reduce the size of the inclination adjusting mechanism. This improves freedom of design of the car body structure, and also improves livability of the car interior.
REFERENCES:
patent: 2560181 (1951-07-01), Morvice
patent: 3216766 (1965-11-01), Tabor
patent: 4070058 (1978-01-01), Muehling
patent: 4408799 (1983-10-01), Bowman
patent: 4700587 (1987-10-01), Bianchi et al.
patent: 5593210 (1997-01-01), Schwarzbich
patent: 5896973 (1999-04-01), Hochmuth et al.
patent: 6032777 (2000-03-01), Denis
patent: 1011446 (1965-12-01), None
Hori Masaharu
Kurita Masahiro
Jr. Milton Nelson
NTN Corporation
Wenderoth , Lind & Ponack, L.L.P.
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