Rocking Chair

One typical rocking chair of the prior art includes a pair of rocking cams mounted in side-by-side relationship on opposite sides of the chair respectively. The cams are rigidly fixed to the seat frame and have arcuate surfaces engaged against a fixed base with tension springs located between the cams and the base to impose a constant bias on the cams. The cams are rockable along an arcuate path determined by the shape of the cam surface which engages the base. Such a rocker is shown by way of example in U.S. Pat. No. 3,730,585. While the cam construction of these types of rockers have the advantage of simplicity, the rocking motion of the seat including the path of movement of the seat is governed by the shape of the cams which, at times, can produce undesirable forward or rearward lurching movement at the extremes of travel.

Another type of rocking chair utilizes linkage mechanisms to provide rocking as well as translatory movement of the seat relative to the base to achieve a different type motion similar to a glider chair. Such a chair is shown, for example, in U.S. Pat. Nos. 4,536,029 and 4,544,201. While the use of linkages enable a predetermined rocking and gliding motion to be achieved, they are more complicated when compared to the conventional cam assemblies described above. They also suffer from instability in the side-to-side direction of the chair thus requiring torque tubes to overcome this drawback.

The present invention seeks to provide yet another type of motion to a rocker which is believed to have certain advantages over the conventional cam rockers and linkage gliders of the prior art and which, at the same time, does not require complicated linkage mechanisms.

Another object of the present invention is to provide a rocking-type chair having a novel mechanism for imparting motion to the seat of the chair relative to a fixed base or datum. Included herein is a novel mechanism for mounting a seat to a base to provide a predetermined motion to the seat relative to the base.

Another object of the present invention is to provide a novel linkage mechanism for imparting a predetermined motion and seat-balance to a rocking-type chair. Included herein is such a mechanism that may be designed in a variety of ways to achieve different types of predetermined motion as desired.

A further object of the present invention is to provide a novel rocking chair whose seat will achieve a predetermined motion including rocking and translatory motion relative to a fixed base.

Another object of the present invention is to provide a rocking chair which utilizes rocker cams in a simple linkage arrangement to mount the seat relative to a fixed base.

A still further object of the present invention is to provide a motion mechanism for a rocker-type chair that is relatively simple and economical in construction and may be easily incorporated in various styles of chairs including recliner chairs.

In summary, the present invention, according to a preferred embodiment, is a motion mechanism including two rocker cams located one behind the other between a seat and a base with the rocking surfaces of the cams engaged against one of the seat and base while being movably connected to the other of the seat and base to be movable relative thereto.

Other objects and advantages will become apparent from the following more detailed description of the attached drawings in which:

FIG. 1 is a side elevational view of a rocker-type chair incorporating a preferred embodiment of the present invention with parts shown in cross section;

FIG. 2 is a cross-sectional view taken generally along lines 2--2 of FIG. 1;

FIGS. 3 and 4 are diagrammatic plan views of second and third embodiments of the present invention.

Referring to the drawings in detail, there is shown in FIGS. 1 and 2 for illustrative purposes only, a rocking-type chair incorporating a preferred embodiment of the present invention. The chair may have conventional frame and upholstery constructions including a base generally designated 10 comprised of opposite side rails 12 interconnected by cross rails 14. The frame of the seat which is generally designated 16 includes upper and lower side rails 18 and 20 and crossrails 19 and 21. A front crosspiece is also provided as are armrests 24. A seat cushion is designated by 28 while the upholstery of the seat frame is designated by 26. The chair also includes a backrest generally designated 30 having upholstery 32.

In accordance with the present invention, the seat 16 is mounted to the base 10 by a novel mechanism including a pair of cam assemblies 40 located one behind the other between the seat and the base. In the preferred embodiment shown in FIGS. 1 and 2, there are two cam assemblies 40 provided in tandem on each of the opposite sides of the base as shown in FIG. 2.

As shown in FIG. 1, the cam assemblies each include a cam 41 having an arcuate rocking surface 42 which, in the preferred embodiment, is at its lower end and engaged against the base rail 12. The upper end of the cam in the preferred embodiment is pivoted by a pivot pin 44 to the seat frame. In the preferred embodiment shown, the seat frame is provided with a metal bracket 60 to which the cam is pivoted at 44 by a pivot pin. Bracket 60 has a horizontal flange 61 fixed by screws 62 to the lower rail 18 of the seat frame. In one specific construction, the cam may be made from a wooden block which includes the rocking surface 42; and a vertical plate 46 fixed to one side of the block by fasteners 48. Pivot pin 44 is received through the upper end of plate 46. Moreover, the cam assemblies on opposite sides of the chair are integrated through a cross bar fixed to and between the cams.

Each cam 41 is biased to the normal position shown in FIG. 1 by means of tension coil springs 52 secured between brackets 54 and 55 fixed respectively to base rail 12 and cam 41 in conventional manner. It will be understood that springs 52 are constantly under tension and bias the cams and seat to the normal upright position shown in FIG. 1.

Although in the preferred embodiment shown in FIGS. 1 and 2, the cams 41 are arranged with their rocking surfaces 42 engaged against the base, in an alternative embodiment not shown, one or both of the rocking surfaces may be disposed at the upper ends of the cams in engagement with the seat frame and with one or both of the lower ends of the cams pivoted to the base.

In operation of the chair, when the seat is rocked backwardly (for example) on the rocking surfaces 42 of the cams, the seat frame will pivot relative to the cams 41 and undergo translatory movement in the rearward direction relative to the base as well as rocking movement. During such motion, the pivot pin 44 may move along the phantom line illustrated in FIG. 1 to the position designated by 44a. Such motion provides a desirable arc of travel of the seat which arc is of suitable length and pitch or radius of curvature so as to provide smooth rocking motion free of lurching movement at the opposite extremes of travel. Moreover, the present invention allows various types of desirable motion or rocking balance of the seat to be achieved simply by choosing the appropriate radius of curvature of the rocking surfaces; or the spacing between the cams on each side of the chair; or the elevation of the pivot or mounting point (44) of the cams. A variation in any one of these factors will effect the motion of the seat. Moreover, the radii of curvature of the rocking surfaces 42 may be varied within each associated pair of cams to provide desired motion. For example, in the embodiment shown in FIG. 1, the rocking surfaces 42 of the front cams may have a radius of curvature of 13/4" and the rocking surfaces of the rear cams a radius of curvature of 13/8". It will be appreciated that the two cam assemblies 40, together with the seat frame 16 and base 10, comprise, in effect, a "four bar" linkage but wherein two of the bars are flexible to allow predetermined path of movement to be achieved by the seat frame. Although the cams 41 may be pivoted to either the seat frame as at 44 or the base (not shown), other types of movable or flexible connections may be utilized in order to achieve a desired type of motion.

Other types of cam arrangements may also be employed in keeping with the present invention. Note, for example, FIG. 3 wherein a triangular arrangement is shown in which one cam assembly 40a is located at a central portion of the base at the forward end thereof with two cam assemblies 40b located behind cam assembly 40a on opposite side portions of the chair. The side and crossrails of the base are designated 12a and 14a respectively. In FIG. 4 only two cam assemblies 40c and 40d are employed, one aligned behind the other along a central axis of the chair.