Armrest Attachment for Chair

This invention relates to an armrest for a chair having a tubular frame, the armrest having a metal frame with end sections which are configured to frictionally engage the frame of the chair.

Chair armrests are usually manufactured separately, and then assembled to a chair during the final stages of manufacture. Various methods for attaching armrests are known in the art. One method used in the past included pressing a male member having a tapered portion frictionally into a tube forming part of a chair frame. However, small changes in the dimensions of the male member or the tube result in large changes in the amount of force required to insert or remove the male member. Therefore, this prior art armrest attachment requires close tolerances when manufactured to create the necessary friction for secure engagement while simultaneously avoiding excessive friction which would make assembly difficult. In addition, this prior art armrest attachment method is not as self-aligning during insertion as desired, and therefore it often requires additional effort to attach the armrest to the chair frame correctly. Other prior art attachment methods include the use of fasteners or spring devices which are not easily assembled and involve "extra" parts. These attachment methods not only undesirably increase the cost of the chair, but also often detract from the appearance of the chair.

Therefore, there is a need for an armrest having an attachment that overcomes the above problems and that provides an inexpensive, secure attachment which does not require fasteners or precise tolerances. Further, an armrest attachment method is desired that is self-aligning, and further that allows for quick attachment without use of complex machinery. Still further, there is a need for an attachment method that does not become loose over a period of time, and also that provides an uncluttered, aesthetically pleasing appearance.

The present invention includes an armrest having a metal reinforcement with an intermediate section and downwardly protruding configured sections. The configured sections have vertically and horizontally spaced apart portions for frictionally engaging open ends of a tubular chair frame. The armrest includes a polymeric body molded to the metal reinforcement and adapted to support for a seated user's forearms.

The present invention provides numerous advantages over the prior known armrest attachment articles and methods for chairs. The attachment is simple and secure, and is configured to minimize the steps required for assembly. In particular, the armrest can be easily and securely press-fittingly attached to a chair frame without the use of separate fasteners. The ends of the armrest are self-aligning, and may be pressed into the tubes by automatic machinery, or manually with a mallet. In addition, the armrest attachment also does not require precise tolerances to create an adequate, but not excessive, frictional engagement in the chair frame. The simplicity, ease of assembly, and lower tolerance requirements provide a low-cost, durable armrest attachment. The absence of externally visible fasteners provides an aesthetically pleasing appearance.

These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings.

FIG. 1 is a front perspective view of a chair incorporating the present invention;

FIG. 2 is a partially exploded, perspective view of the chair shown in FIG. 1 illustrating the configured end sections of the armrests;

FIG. 3 is a perspective view of the armrest shown in FIG. 2;

FIG. 4 is a top view of the armrest shown in FIG. 2;

FIG. 5 is a side view of the armrest shown in FIG. 2, the open top ends of the vertical frame tubes being shown in phantom lines;

FIG. 6 is a fragmentary elevational view illustrating one end of the armrest in engagement with a tube;

FIG. 7 is a top view of the reinforcement rod portion of the armrest shown in FIG. 2;

FIG. 8 is a side elevational view of the reinforcement rod shown in FIG. 7;

FIG. 9 is a section view taken along the plane IX--IX of FIG. 4;

FIG. 10 is a sectional view taken along the plane X--X of FIG. 4; and

FIG. 11 is a sectional view taken along the plane XI--XI of FIG. 4.

For purposes of description herein, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal", and derivatives thereof shall relate to the invention as oriented in FIGS. 1 and 2. However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

Chair 10 (FIG. 1) includes a frame 1, a backrest 2, a seat portion 3, and a pair of armrests 4a and 4b. Frame 1 preferably includes tubular sections including substantially vertical tubes 5a, 5b, 5c and 5d, and horizontal tubes welded together to form a rigid rectangular framework, although the present invention is contemplated to include other chair frame constructions. Each pair of tubes 5a, 5b and 5c, 5d respectively form a left and right pair of legs.

As best seen in FIGS. 3-8, the armrests 4a and 4b have a metal reinforcement 20 with configured end sections 21, and an outer, urethane cover, or body 28 molded onto reinforcement 20. Armrests 4a and 4b are mirror images, and accordingly only armrest 4a is described hereinafter. It is contemplated that the armrests could be made identical.

As best seen in FIGS. 7 and 8, the metal reinforcement 20 is preferably formed from a steel rod having a circular cross section. The intermediate section of the metal reinforcement 20 has a first elongate intermediate curved portion 25, and further has a second elongate bar portion 26 welded to the first curved portion 25 to provide increased width and strength for supporting a seated user's forearm. The first curved portion 25 extends generally arcuately in a horizontal plane, but with a slight vertical curve. The second elongate bar 26 is substantially straight when viewed from above but with a slight vertical curve corresponding to that of the first curved portion 25. (See FIG. 8). The metal reinforcement 20 has configured end sections 21 that extend vertically and substantially perpendicular to the curved portion 25 and the second elongate portion 26. The distance between the two end sections 21 corresponds to the distance between a pair of upright, spaced apart tubes such as tubes 5a and 5b.

As best seen in FIGS. 3, 4, and 5, the intermediate section of the metal reinforcement 20 is covered with a molded polymeric or urethane body 28 for comfortable support of a seated user's forearm. The urethane body 28 defines a D-shaped aperture 27 in plan view (FIG. 4), which not only provides a distinctive appearance, but that also can be used for grasping by a seated user that is beginning to stand up. As best seen in FIG. 9, the body 28 has end portions 35 adapted to act as stops to limit the engagement of the configured end sections 21 in the open, upper ends of the tubes 5a, 5b, 5c and 5d. The end portions 35 include an annular inner lip 30 and a circular flat surface 29 which form a cavity 31 for receiving the open, upper end of one of the tubes 5a, 5b, 5c and 5d. As seen in FIG. 9, the circular flat portion 29 of the body 28 acts as a stop to limit the length of the end sections 21 that extends into the tubes. When the armrest is fully installed to the frame, the end portion of the tubes is received into the body 28, thereby covering the edges of the tube. The connection between the armrests 4a, 4b and the chair frame 1 is therefore free of unsightly sharp or rough edges.

As best seen in FIGS. 2, 3, 5 and 6, each of the end sections 21 of the armrests 4a and 4b have an intermediate portion 22 and vertically spaced apart portions 23 and 24 that frictionally engage opposing inner surfaces of the tubes 5a, 5b, 5c and 5d near the open, upper end of the tubes. The intermediate portion 22 and vertically spaced apart portions 23 and 24 are formed by three adjacent bends in the metal reinforcement 20. Intrmediate portion 22 forms a transversely-oriented U-shaped bend that contacts the inner surface of the tubes 5a, 5b, 5c and 5d. The U-shaped bend has upper and lower legs forming vertically spaced-apart portions 23 and 24. Two vertically spaced apart portions 23 and 24, are horizontally spaced apart by the intermediate bent portion 22 such that the horizontal or transverse dimension "H" defined by the intermediate portion 22 and vertically spaced apart portions 23 and 24 is somewhat greater than the inside diameter of the tubes 5a, 5b, 5c and 5d. This causes an interference fit when the end sections 21 are installed in the tubes. Therefore, the end sections 21 and/or the tubes 5a-5d resiliently bend slightly when the end sections 21 are inserted into the open, upper ends of tubes 5a, 5b, 5c and 5d. The intermediate portion 22 and the spaced apart portions 23 and 24 are biased into frictional engagement with inner surface of the tubes due to the force resulting from the bending of the end sections 21. The amount of force required to insert or remove the end sections can be varied by changing the amount of interference between the end sections 21 and the inner surfaces of the tubes 5a, 5b, 5c and 5d, or by varying the diameter or surface finish of the rod which forms the end section 21. The armrests 4a and 4b are thereby securely attached to the tubes due to the frictional engagement of the end sections 21 in the ends of the tubes. The spaced apart portions 23 and 24 preferably lie in the same plane as intermediate portion 22, although it is conceivable that a non-planar arrangement could also be developed.

During installation of the armrests 4a and 4b to the chair frame 1, initially only the intermediate portion 22 and the spaced-apart portion 23 are placed into and contact the inner surface of the tubes. As the end section 21 is urged further into the tube, the spaced-apart portion 24 comes into contact with the upper edge of the tube opening. This contact between the two curved surfaces causes the end section 21 to align with the axis of the tube. The engagement of the intermediate portion 22 and the spaced-apart portions 23 and 24 with the cylindrical inner surface of the tubes also resists an overturning moment, such that the armrest does not tend to twist out of engagement during installation.

As will now be apparent, the end sections of the armrests have a shape that is configured to be securely and easily engaged with the open ends of the upright tubes of the chair frame. The armrests end sections may be inserted by means of special equipment or manually with a mallet. The shape and dimensions of the end sections provide secure engagement while still allowing for simple assembly. Notably, it is envisioned that the armrest could be manufactured in several different configurations, such as with separate configured end pieces attached to a main body formed of a structural polymer or other material.

It will become apparent to those skilled in the art that various modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.