Seat unit

Dec. 25, 1962

3,069,701

W. K. MCINERNEY

SEAT UNIT

<img file="US3069701A_D0001.tif" />

Atty.

Dec. 25, 1962

3,069,701

W. K. MCINERNEY

SEAT UNIT

<img file="US3069701A_D0002.tif" />

Dec. 25, 1962

w. κ. mcinerney

SEAT UNIT

3,069,701

Filed Oct. 29, 1959

Sheets-Sheet 3

<img file="US3069701A_D0003.tif" />

Atty.

Dec. 25, 1962

W. K. MCINERNEY

3,069,701

<img file="US3069701A_D0004.tif" />

Atty.

United States Patent Office 3,069,701

Patented Dec. 25, 1962 for connection of the seat unit to the chassis of the vehicle in which it is to be installed.

. The central area of the resilient frame is left substantially unoccupied, and the plane defined by the top of the frame is left unobstructed for receiving an insert which combines spring and foam material. In the preferred form of the invention, a group of coil springs is adhesively secured at one end of the coils to a fabric base, and this sub assembly is then placed in a suitable mold which applies a mass of resilient foam material which becomes bonded to the fabric base and surrounds the springs which have been secured to the fabric. Preferably, the formation of the mold is such as to create an extension of the foam material which overlays the edges of the frame to provide the feeling of softness over the entire upper surface of the seat unit. The fabric is also preferably permitted to extend beyond the foam material so that it can be wrapped around and secured to the frame at convenient points.

The several features of the invention will be analyzed in detail through a discussion of the particular embodiments illustrated in the accompanying drawings. In the drawings:

FIGURE 1 presents a fragmentary sectional view in perspective showing a seat unit embodying the preferred form of the invention.

FIGURE 2 illustrates a plain sheet of the preferred form of material used for the fabric base.

FIGURE 3 illustrates the sub-assembly of a group of coil springs to the fabric base.

FIGURE 4 is a fragmentary section on an enlarged scale illustrating the formation of the foam material around the spring-fabric sub-assembly in a mold.

FIGURE 5 is an exterior end elevation of the completely molded seat insert.

FIGURE 6 js an exterior end elevation of the seat assembly showing the insert in position in the resilient frame.

FIGURE 7 is an enlarged fragmentary section showing the relationship of the coil springs, the fabric base, and the molded foam material.

FIGURE 8 is a fragmentary section showing the protrusion of the mold material through the interstices of the fabric to form resilient button-shaped projections on the bottom of the seat unit which support and protect the fabric base.

FIGURE 1 illustrates the resilient frame of the preferred form of the seat construction, with a portion of the molded seat unit removed to expose the structural details of this frame. The frame indicated generally at 10 includes an upper rear border wire 11, an attachment wire 12, and the parallel wires 13 and 14 which extend around the front and sides to complete the definition of the plane of the top of the structure. The bottom area of the frame is defined by the group of paral'el wires 15—22, together with the border wire 23 extending around the front and sides. Normally, this group of lateral wires will be offset in the central area as shown at 24 to acccmmodate the irregularities in the floor of the vehicle. A group of coil springs 26 extends around the front and sides between the upper and lower wires, and the group 27 a'ong the rear to provide for relative movement and resilience as load is applied to the seat. The framework as thus defined is secured by any convenient system (not shown) to the floor or chassis of the vehicle.

The central mo'ded insert 28 is an extreme’y important component of the total structure provided by the invention. . The manner in which this e’ement is constructed is best illustrated by a comparison of FIGURES 2, 3, and 4. A sheet of w'de-mesh fabric is shown in FIGURE

2, and is used as a base to which the other components are assembled. In the preferred form of the invention,

3,069,701 wn· x- , SEAT UNIT Walham K. Mcitaemey, Grand Rapids, Mich., assignor to

Mcinerney Spring and Wire Company, Grand Rapids, Filed Oct. 29,1959, Ser. No. 849,676

Claims. (CI. 5—351)

This invention relates to the construction of seat units and _lt is the broad purpose of the invention to combine the desirable features of a resilent foam cushioning material w.th those of a spring assembly in a structure which does not require a large number of hand assembly operations. The softness and resulting comfort of a foam cushion are well-known, and yet the exclusive use of this material as a seat unit dees not result in a satisfactory construction. As the weight of the occupant is app ied progressively to the seat, the contact is initial· y m de over a very hm.ted area. This results in a very limited resistance to the weight, with the resulting feeling of extreme softness. The ability of the cushioning material to resist weight is in a direct function of the area over which the weight is applied, since the behavior of the material is somewhat analogous to the generation of a liquid pressure. As soon as the occupant becomes fully 25 supported by the foam cushion, the weight becomes distributed over a sufficient area so that substantial further deflection of the material does not take place. This arrangement therefore gives a very limited absorption of vibration and read shock unless a material of such a high 30 degree of softness is used as to make the unit of completely unacceptable original dimensions.

A spring assembly, on the other hand, has the desirable feature of being able to absorb vibration and road shock after the full weight of the occupant has been applied 35 This is primarily due to the fact that the springs exert a resistance to the weight at a finite number of points and no.hing analogous to the liquid pressure of the cushion ever develops. A spring can also be confined so that the or.ginal position of the spring in the seat unit 40 is pre-loaded. This possibility enables the designer to establish the pre-loading of the spring at a point just slightly in excess of ths effect of the weight of the occupant, w.th the result that a subsequent increase in vertical force due to accelerations will cause the spring to yield readily without submitting the occupant to jostling.

The desirable features of each of the two types of construction have been widely recognized. Upholsterers of both household and vehicle seating have progressively evolved a standard seat construction which utilizes a ⁵⁰spring base overlaid with a padding assembly in order to give the occupant the softness of the padding with the depth resilience of the spring assembly. The padding material has conventionally included a foamed rubber or synthetic, or felted pads made of any one of the fibrous ⁵⁵materials. The primary objection to this combined seat construction is the cost of assembling it, as it inherently requires a vast number of intricate hand assembly operations. A quality seat unit will normally have a series of laminations of fabric and padding, all of which require ⁶⁰careful placement and attachment around notoriously irregular surfaces. The assembly of the spring base unit is itself a very complex operation requiring a high degree of skill, with the tolerances in bendins operations being necessarily sufficiently large to practically eliminate 65 the possibility of a fully automated assembly system.

In the preferred form of this invention, applicant has provided a resilient wire framework primarily for defining and maintaining the space which the seat structure occupies. This framework may include a series of springs 70 of coil or other formation around the periphery, if desired. The framework will also usually provide points

3,069,701 ³ this fabric is of a type commonly known as “Linocloth” or “Dixinet.” This particular material is of cotton with a thread count of live and one-half by six, and has a break test (utilizing three inch jaws) of approximately eighty eight pounds in the warp and seventy-four pounds in the fi.ling. This sheet of fabric will be designated with the reference numeral 29. A group of conventional coil springs 30 is positioned on the fabric base 29, and one end of each of the coils is preferab’y adhesively bonded to the fabric. Many commercial adhesives are available for th's purpose, and the particular one selected will be influenced somewhat by the finish on the springs and by the form of impregnation or finish of the fabric material.

The sub-assembly of coil springs and fabric base shown in FIGURE 3 is placed in a mold 31, as shown in FIGURE 4. The portions of the fabric surrounding the group of springs are laid over the surfaces of the. mold, and a quantity of foamed material indicated at 32 is then added and cured in position. A suitable top.(not shown) will normally be used to confine and estab, ish the upper surface 33 of the completed insert. Portions of the fabric 29 are permitted to extend beyond the edge of the mo'ded material 32 as shown at 34 to facilitate attachment of the insert to the frame 10. The method of attachment is' conventional in the upholsterer s art, and includes the use of “hog-rings” 35. These devices are essentially deformable C-shaped rings which are capable of receiving a wire of the frame with the fabric portion 34 already Wrapped around it. The ring embraces both, the fabric and the wire, and is then closed with, a plier or similar tool to grip the components securely in position. These devices are applied at random convenient positions around the upper frame structure as best shown in FIGURE 6.

The details of the formation of the mo'ded insert 28 are shown on an enlarged scale in FIGURES 7 and 8. The points of the a;pii ation of adhesive which secure the springs 3® to the fabric 29 are shown at 36, and the installed relationship of the molding material 32 and the springs 30 is clearly shown in which the springs are submerged within the bulk of the molded material. This molded material is preferably a form of foamed polyurethane, but other synthetics or natural materials are contemplated for incorporation in the invention. Conventional molding techniques utilizing foam material will result in the generation of at least some of the foaming action within the mold. This effect tends to urge the material into the corners and recesses of the mold very effectively, and also has the very desirable characteristic or urging the foamed material through the interstices of the fabric to form a series of button-shaped projections as shown at 37 in FIGURE 8. When fully cured, these projections form resilient cushions which guard the fabric 29 against direct contact with the frame or with the structure of the vehicle, and also maintains a spaced relationship between the ends of the spring 30 and the surrounding metal supporting structure.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire in4 vention disclosed herein, except as I am limited by the prior art.