SEAT CUSHION SPRING ASSEMBLY

ASSEMBLAGE DE RESSORTS POUR SIEGE

English Abstract

ABSTRACT
A spring assembly for a seat cushion or the like. The
assembly consists of a flexible cover and a coil spring. The
flexible cover has a pocket proportioned to receive the coil
spring. The coil spring comprises a length of wire wound upon
itself about a longitudinal axis to form an open coil spring
having a plurality of turns. The turns of the spring have a
radius generated from the longitudinal axis which varies
continuously along the length of the spring and is a maximum at
the center of the length of the spring and decreases
progressively toward each end of the spring such that, upon
compression of the spring adjacent turns are radially spaced from
one another to provide clearance therebetween to accommodate
buckling of the wall of the cover without pinching of the cover
therebetween.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows.
1. A spring assembly for a seat cushion or the like
comprising:
a) a flexible cover having a wall defining a pocket
proportioned to receive one coil spring, and
b) a coil spring comprising;
a length of wire wound upon itself about a longitudinal
axis to form an open coil spring having a plurality of turns, the
turns of said spring having a radius generated from said axis
which varies continuously along the length of the spring and is a
maximum at the center of the length of the spring and decreases
progressively toward each end of the spring such that, upon
compression of the spring adjacent turns are radially spaced from
one another, said coil spring being located in said pocket of
said cover, the radial spacing of said turns of the compression
spring being sufficient to provide clearance therebetween to
accommodate buckling of the wall of the cover without pinching of
the cover therebetween.
2. A spring assembly for a seat cushion or the like
comprising:
a) a flexible cover having wall defining a pocket
proportioned to receive one coil spring,
b) a coil spring comprising;
a length of wire wound upon itself to form a coil
spring which has at least one open central convolution and end
convolutions extending from opposite ends of the central

convolution, said spring being located in said pocket of said
cover, the radius of said convolutions decreasing progressively
from the center of the central convolution toward each end of the
spring such that upon compression of the spring, adjacent
convolutions are radially spaced from one another to provide
clearance therebetween to accommodate buckled portions of the
wall of the cover therebetween without damage to the wall of the
cover in use.
3. A cushion for a seat comprising:
a) a body of foamed plastic material having a plurality
of spring chambers formed therein,
b) a spring assembly in each of said chambers, said
spring assembly comprising;
i) a flexible cover having wall defining a pocket
proportioned to receive one coil spring,
ii) a coil spring comprising;
a length of wire wound upon itself to form a coil
spring which has at least one open central convolution and end
convolutions extending from opposite ends of the central
convolution, said spring being located in said pocket of said
cover, the radius of said convolutions decreasing progressively
from the center of the central convolution toward each end of the
spring such that upon compression of the spring, adjacent
convolutions are radially spaced from one another to provide
clearance therebetween to accommodate buckled portions of the
wall of the cover therebetween without damage to the wall of the
cover in use.

Description

3~
D31-1672-167
This invention relates to spring cushions~ In
particular, this invention relates -to spring cushions in which
pocket springs are located.
PRIOR ART
For many years, springs which are used in upholstered
furniture have been located in a pocket of a fabric cover to
prevent direct contact between the wire body of the spring and
the surrounding seat. The cover which has conventionally been
used as a simple cheesecloth cover serves to protect the
surrounding fabric of the cushion and provide increased wear
characteristics to the cushion. ~he covers themselves are,
however, subject to wear and when worn -through, the spring can
make contact with the fabric of the seat and ultimately wear
through the fabric of the seat.
To avoid any reduction in the effectiveness of the
spring, it is necessary to avoid the use of a heavy fabric cover
and consequently, the difficulties which are being experienced as
a result of wear of the cover cannot be effectively overcome
merely by using a heavier cover.
I have found that I can retain the lightweight cover
which is conventionally used and increase the useful life of the
spring assembly by designing the spring so that it does not nip
or pinch the cover when it is compressed.
2~

3'~
D31-1672-167
According to one aspect of the present invention, a
spring assembly for a seat cushion or the like which comprises a
flexible cover having a wall defining a pocket proportioned to
receive one coil spring, and a coil spring comprising; a length
of wire wound upon itself about a longitudinal axis to form an
open coil spring having a plurality of turns, the turns of said
spring having a radius generated from said axis which varies
continuously along the length of the spring and is a maximum at
the center of the length of the spring and decreases
progressively toward each end of the spring such that, upon
compression of the spring adjacent turns are radially spaced from
one another, said coil spring being located in said pocket of
said cover, the radial spacing of said turns of the compression
spring being sufficient to provide clearance therebetween to
accommodate buckling of the wall of the cover without pinching of
the cover therebetween.
The invention will be more clearly understood after
reference to the following detailed specification read in
conjunction with the drawings wherein;
Figure 1 is an exploded view of a seat cushion
constructed in accordance with an embodiment of the present
invention,
Figure 2 is a partially sectioned view of a coil spring
enclosed ln a cover in accordance with an embodiment of the
present invention,
Figure 3 is a sectional side view of the spring of
Figure 2 in a partially compressed configuration.

~Xll~
D31-1672-167
With reference to Figure 1 of the drawings, the
reference numeral 10 refers ~enerally to a cushion construc-ted in
accordance with an embodiment of the present inventionO The
cushion comprises a central body portion 12 and a pair of end
panels 14. A plurality of circular passages 16 extend through
the central body portion 12 and a spring assembly 18 is located
in each passage 16.
The spring assembly 18 comprises a coil spring 20 and a
fabric cover 22. The coil spring 20 co~prises a single leng-th of
wire 24 in which is wound upon itself and which has a radius of
revolution Rl generated from the axis R which varies continuously
over the full length of the spring such that it i5 at a maximum
radius Rl substantially centrally of the length of the spring,
~he radius decreasing progressively from each side of the center
of the length of the spring toward each end convolution.
As a result of this structure, when the spring is
compressed as shown in Figure 3, a narrow gap will always exist
between adjacent turns of the spring. This narrow gap provides a
space into which the cover 22 may buckle without being pinched
between the adjacent turns of the spring.
I have found that this spring configuration serves to
reduce wear and tear on the cover which in turn, reduces wear and
tear on the structure of the cushion.
The spring 20 is located in the pocket 21 of the cover
22 so as to be completely enclosed by the cover 22.

l~ L~L
D31-1672-167
The spring ~0 is made from a single length of spring
steel and the cover 22 .is preferably made from a conventional
cover forming material such as cheesecloth or the like.
These and other advantages of the spring assembly of
the present .invention will be apparent to those skilled in -the
art.