Zero Chuck Recliner With Floating Pawl

The invention relates to selectively positionable releasably locking hinge devices, and especially to adjustable car seat back hinges.

Selectively adjustable, lockable hinges are generally well known. In essence, such hinges consist of a pair of hingably interconnected members mutually relatively rotatable about a common pivot. Prior locking devices typically include those having a pawl, which is pivotally connected to one hinge member, and which can be rotationally biased about its pivot by way of a cam acting on a cam follower surface of the pawl thereby rotating the pawl into interferring relation with teeth arranged around an arcuate portion of the other member. As a result the locked hinge is secured in locked relation by a balanced distribution of forces between the pivots of the cam, the locking pawl, and the hinge.

In many applications, including by way of example and without limitation, automobile seat back hinge applications, there is a requirement for the two members of the hinge to be rigidly locked, with a minimum of play. One element of "play" results from clearances that are necessarily a part of any device containing parts adapted for mutually relative movement. "Clearance" is the difference in size between mating parts prior to their assembly. Typically the clearance on cylindrical parts may be expressed as radial clearance or diametrical clearance. Positive clearance implies that the inside dimension of the female part is larger than the corresponding outside dimension of the male part. In typical mechanical applications a running fit requires about 0.001 inches of radial clearance for a one inch diameter shaft. A clearance of 0.003 inches on a one inch shaft is considered to be a loose fit. In typical automotive seat back hinge manufacturing, mass production processing techniques often result in clearances of 0.008 inches.

The amount of clearance typically found in seat back hinges of the type above-described, introduce an element of play called "chuck" into the mechanical system of which the hinge is a part. Note that "chuck" is not the "play" which is introduced through the flexure of any mechanical components. Rather, the term is expressly used and understood in the automobile seat back art to mean the component of play which results from mechanical lost motion due to clearances between interconnected parts, when leverage forces are applied across the hinge.

"Chuck" is a highly undesirable characteristic in automobile seat back hinges, for both safety and aesthetic reasons. In any case, considerable energy has been applied in the past in search of ways to reduce and preferably minimize "chuck".

There is provided according to the invention a selectively positionable, releasably lockable hinge device comprising a pair of hingably connected hinge members which are mutually relatively rotatable about a common pivot. These members are positionable relative to one another over a pre-determined range of relative rotation, in at least one mutually locked position, (and preferably in any one of a plurality of mutually releasably locked positions), by an elongate locking pawl that is selectively movable between locking and unlocking positions between the members. The locking pawl includes first and second longitudinally spaced, toothed portions which, when the locking pawl is biased into a locking position, are interferingly and wedgingly engaged with respective corresponding surfaces of the two members. The pawl thereby engages the two members in rigidly bridging interlocking relation. The wedging action of the locking pawl on both of the members serves to take up any radial clearances between relatively rotating parts of the hinge and its locking mechanism. As a result, the hinge of the present invention effectively eliminates chuck from the locked hinge of the present invention. The floating pawl, having no fixed pivot (or associated clearances) does not contribute to any component of "chuck" .

In the course of the following detailed description of the invention, reference will be made to the accompanying drawings of which:

FIG. 1 is a partially exploded elevated side view in perspective of an automotive seat back hinge embodying a preferred form of the present invention; and,

FIG. 2 is an elevated side view in cross-section through the hinge depicted in FIG. 1, illustrating locked and unlocked positions thereof.

Referring now to FIG. 1 of the drawings there is illustrated a releasably lockable hinged device according to the present invention, shown in a partially exploded elevated side view of an automotive, releasably lockable seat back hinge device 1. Device 1 comprises hingedly connected means including seat hinge member 2 and seat back hinge number 3. Hinge member 2 includes a seat cushion side plate 2a, and a second, transversely aligned and spaced apart side plate 2b. The seat and seat back hinge members 2 and 3 are relatively rotatable about a common pivot 4, and are thereby mutually positionable in an at least one mutually releasably locked position.

Mutual locking of the seat and seat back hinge members 2 and 3 is accomplished by way of locking pawl 5, which is selectively movable between a locking position as illustrated in FIGS. 1 and 2, and an unlocking position 7 illustrated in phantom in FIG. 2 only. A first surface portion 8 and a second surface portion 9 of pawl 5 both have teeth, 8a and 9a respectively, arranged thereon.

With the locking pawl biased into locking position 6, teeth 8a and 9a are positioned in interfering wedging engagement with teeth 10a and 11a arranged on respective corresponding surfaces 10 and 11 of seat and seat back hinge members 2 and 3. With the pawl 5 positioned thusly in locking position 6, pawl 5 engages members 2 and 3 in bridging interlocking relation therebetween. This secures members 2 and 3 against any relative mutual rotation about common pivot 4.

As illustrated, locking pawl 5 includes a cam follower surface 13 operably interconnected with a rotatable cam surface 12 which is lever operated through an integrally formed lever 14 to act against follower surface 13 and thereby bias locking pawl 5 between locking position 6 and unlocking position 7.