Control Mechanism for a Chair or the Like

This invention relates to a control mechanism for a chair or the like, and particularly to a tilt and height control mechanism for a chair.

Tilt controls for chairs are known. Most are cumbersome and complicated, and oftentimes not reliable. The present invention has, for its principal object, the providing of a control mechanism for a chair in which tilting action may be easily and effectively controlled, as well as chair height adjustment.

In a preferred embodiment of the present invention, tilt and height control are achieved through use of a single self-contained adjustment mechanism controlled by a single adjustment lever. In one position of the lever, the chair is "locked" so that it may not be tilted. In another position of the lever, the mechanism is "unlocked" and the chair may be tilted to any comfortable position. In still another position of the lever, the chair height may be adjusted, as desired.

This action is achieved in a preferred embodiment of the invention by use of a control housing that is attached to a chair seat and a pivot block that is attached to a chair pedestal or similar chair support mechanism. The control housing and pivot block are mounted for pivotal movement with respect to each other about a pivot shaft. An actuator block is supported for movement along that shaft and carries a pin thereon. The control housing includes a flange which engages the pin in one of the positions of the actuator block along the shaft, thereby preventing pivotal movement of the control housing and pivot block. In another position of the actuator block along the shaft, the pin and flange are out of disengagement (the flange is discontinuous), so that pivotal movement of the control housing and pivot block can take place. In this fashion the chair is either locked against tilting or unlocked for tilting. In another position of the actuator block along the shaft, a cam surface on the actuator block engages the actuator control of a gas cylinder mechanism, permitting the height of the chair to be adjusted. The position of the actuator block along the pivot shaft may be controlled by a spring-loaded ball carried by the actuator block which engages grooves in the pivot block corresponding to the tilt locking and tilt unlocking positions of the actuator block. The actuator block preferably is spring-biased out of the position thereof along the shaft in which the actuator control of the gas cylinder mechanism is activated.

The assembly preferably includes a wear strip that is mounted to the pivot shaft, is formed of spring metal, and has a surface that is positioned adjacent to the cam surface of the actuator block. The actuator block is moveable along the pivot shaft with respect to the wear strip, and the wear strip is adapted to engage the actuator control of the gas cylinder mechanism.

The control housing and pivot block pivot with respect to each other, as noted above, about the pivot shaft. A coil spring is utilized urging the control housing and pivot block toward a predetermined angular relationship with respect to each other about that shaft. The coil spring provides the conventional restoring force against the tilting of the chair tending to return the chair to a non-tilted position.

The invention will be more completely understood by reference to the following detailed description.

FIG. 1 is a sectional view of a tilt control mechanism embodying the invention.

FIG. 2 is a view similar to FIG. 1, showing the tilt control mechanism in a tilting position.

FIGS. 3-5 are partial sectional views, taken generally along the sections 3--3, 4--4 and 5--5 in FIG. 1.

FIG. 6 is an exploded view of the tilt control mechanism of FIG. 1.

Referring first to FIG. 6, the parts that constitute the tilt control mechanism are as follows:

(a) a control housing 10,

(b) a pivot block 12,

(c) an actuator block 14,

(d) a pivot shaft 16,

(e) snap rings 18,

(f) spring tension adjustment screw 20,

(g) threaded nut 22,

(h) spring adjustment washer 24,

(i) coil spring 26,

(j) spring plunger 28,

(k) bearing 30,

(l) adjustment rod 32,

(m) bearings 34 for pivot block 12,

(n) tilt lock pin 36 threaded into actuator block 14,

(o) spring 38,

(p) ball catch 40, and

(q) wear strip 42.

Not forming part of the invention but also shown in FIG. 6 is the upper portion 44 of a gas cylinder mechanism that includes an actuator control 46. The gas cylinder mechanism 44 constitutes the upper portion of a chair pedestal or similar support mechanism (not shown).

The control housing 10 and pivot block 12 are mounted for pivotal movement with respect to each other about the axis of pivot shaft 16 which is carried in pivot block 12 by virtue of holes 12a in that block. The pivot block mounts upon the upper portion of the gas cylinder mechanism 44. Bearings 34 are mounted in holes 12a in the pivot block to support the pivot shaft 16. The ends of the pivot shaft 16 are carried in holes 48 in the control housing 10, and snap rings 18 retain the shaft in place. Actuator block 14 rides along the shaft 16, and includes a tilt lock pin 36 which is threaded into the actuator block. This lock pin engages a flanged portion of the control housing, i.e., flange portion 10b shown in FIG. 4 in one position of the actuator block along the pivot shaft 16. The flange 10b is discontinuous and includes a cut-away portion 10c thereof so that, when the pin 36 is in the region of the cut-away portion 10c, the control housing 10 is free to pivot with respect to the pivot block 12. Thus, when the actuator block 14 is in the position shown in FIG. 4, the tilt lock pin 36 engages the flange 10b, preventing any tilting action.

Movement of the actuator block 14 along the axis of shaft 16 is occasioned by adjustment rod 32 which is threaded into the actuator block 14 and which passes through hole 10d in control housing 10.

The actuator block 14 includes a spring-loaded ball 40 which engages grooves 12b and 12c in the pivot block 12 in two of the positions of the actuator block 14 along the shaft 16. Specifically, when the ball 40 is in the groove 12b, the actuator block is retained in the position shown in FIG. 4, in which the tilt control mechanism is locked against tilting. When the ball 40 rides in the groove 12c, the pin 36 is in the dashed line position shown in FIG. 4 (the tilting position of the tilt control mechanism), and the mechanism is retained in this position by the ball in the associated groove.

The same adjustment rod 32 is used to control height adjustment by moving it further to the left (with respect to the orientation in FIG. 3). In this case, the actuator block 14 compresses spring 38 (FIG. 3) which tends to return the actuator block 14 to the free tilting position in which the ball 40 rides in the groove 12c. When the actuator block 14 is moved to the left with respect to FIG. 3, the actuator block causes the gas cylinder mechanism to be actuated, as shown in FIG. 5. Specifically, the lower part of the actuator block 14 constitutes a cam surface, designated 14a. As the actuator block 14 is moved to the left in FIG. 5, the actuator control 46 of the gas cylinder mechanism is activated (by being pushed downwardly) thereby achieving a height adjustment of the chair or other mechanism which is being controlled. As noted, the spring 38 tends to return the actuator block 14 to the position shown in FIG. 5, which is the non-actuated position of the actuator control 46.

To provide better control of the height adjustment mechanism, the wear strip 42 is included. This is a piece of spring metal, for example, shaped in the form of a yoke so that it is positioned fixedly with respect to the pivot shaft 16.

The wear spring 42 is positioned adjacent to the cam surface 14a, and the actuator block 14 is free to move along the wear strip. Thus, contact with the actuator control 46 is actually made by the wear strip 42 and not the cam surface 14a. This avoids grooving of the cam surface by the actuator control 46.

The tilt control mechanism is spring biased by use of spring 26 which is carried by spring plunger 28. The spring adjustment washer 24 rides in one end of the spring 26, as shown in FIG. 1. The threaded nut 22 is carried in the control housing 10, as shown in FIG. 1, and the spring tension adjustment screw 20 is adjusted to control the tension of the spring 26. The spring plunger 28 bears against surface 12d of the pivot block 12, as shown in FIG. 1. Bearing 30, which may be of plastic material, serves to prevent wear and provides for smooth, noiseless movement between the end of the spring plunger 28 and the surface 12d of the pivot block 12 against which it bears.

In practice, the control housing 10 is mounted on the underside of a chair seat, for example, by means of screws (not shown) which pass through holes 10a in the control housing 10. The pivot block 12 is attached to the upper portion of a chair pedestal or similar support mechanism, such as gas cylinder structure 44. The single control rod 32 is used to shift the actuator block 14 between the chair tilt-lock position, chair free-tilt position, and chair raise-lower position, as described above.

It is apparent that the presently preferred embodiment described above is subject to modification. The invention, accordingly, should be taken to be defined by the following claims.