Upholstery fabric

Abstract: An upholstered three dimensional structure incorporating an internal core (1) and a knitted fabric cover (2), in which there is provided in the cover (2) a line (7) along which the fabric is less extensible compared to the surrounding fabric, the line being positioned on the fabric such that the line curves over an edge (8) of the core so that on stretching the fabric over the core (1) the less extensible line is displaced from the general plane of the fabric towards the core.

Description: This invention relates to upholstery fabric intended to cover at least part of the surface of a three-dimensional structure. The invention has particular, but not exclusive, reference to upholstery for an automobile seat, or a seat for other vehicles such as trains, aeroplanes, boats, buses, lorries or other modes of transport. As well as upholstered seats in vehicles or other modes of transport the invention may be used in other upholstered structures in vehicles and modes of transport, such as side cushions for protection or decoration. Further additionally the invention may be used in upholstery for non-transport applications such as seats in houses, offices etc, and upholstered structures generally used for appearance or padding or both. The usual method of manufacturing a vehicle seat cover involves converting yarn into woven fabric, cutting out shaped pieces of the woven fabric to make the seat back cover and subsequently sewing these pieces together to form the base and back covers. It is also necessary to provide anchorage devices at the edges of the base and back covers to enable attachment of the covers to respective cushions. Usually these anchorage devices take the form of hollow sewn hems which can be secured to metal rods recessed into the cushions. If the base and/or back cushions comprise bolsters, it is also necessary to provide anchorage devices, usually in the form of open looped flaps, on the undersurface of the cover, in order to conform the cover to the shape of the upper surface of the cushion. Apart from being wasteful in fabric, this method of manufacturing vehicle seat covers is extremely time-consuming and is therefore very costly. Additionally, the amount of time taken to design and produce the warps for weaving; weave the fabric; stenter the fabric; design the patterns; cut and sew, means that design changes in woven seat covers can take eighteen months or more to implement. Recently, it has been found possible to knit one-piece upholstery fabrics which, without the need for sewing portions together, have the desired shapes to serve as covers for the base and back cushions of a vehicle seat, and incorporate the anchorage devices for the tubes. See UK Patent Application No.2,223,034 A. An aim of the present invention is to provide such a piece of knitted upholstery fabric with a "mechanical structure" further facilitating its retention on a three-dimensional support, such as a vehicle seat cushion. By the present invention there is provided in an upholstered three dimensional structure incorporating an internal core having at least one edge and a knitted fabric cover overlying said core, the improvement which comprises providing in the cover a line along which the fabric is less extensible compared to the surrounding fabric, the line being positioned on the fabric such that the line curves over the edge of the underlying core so that on stretching the fabric over the core the less extensible line is displaced from the general plane of the fabric towards the core. The core may be a foam bun. The line may engage with a recess in the core, or may cut into the core. The upholstered three-dimensional structure may be a seat, or a part of a seat such as a squab or back. The line may be formed by knitting the fabric cover such that it is less extensible along the line by virtue of the number, density or type of stitches used. Alternatively at least one reinforcement member may be knitted into the fabric along the line. The reinforcement member may be of a material inherently less extensible than the fabric on knitting. Alternatively, the reinforcement member may be treated after knitting to form the line. The treatment may be heat treatment. The heat treatment may be by steam. The reinforcement member may be a steam shrinkable yarn. The fabric may be knitted on a flat V-bed machine having independently operable needles. The fabric may be double jersey fabric. The reinforcement member may be knitted in or inlaid in a course-wise direction. The reinforcement member may be knitted on the rear needles only and may be knitted on only every 2nd, 3rd, 4th, 5th or 6th needle, the reinforcement member being floated over the vacant needles between the beds and therefore between the front and rear of the fabric. There may be a plurality of reinforcement members, each course of reinforcement members picking up the next adjacent needle to the previous course. There may be as many courses as there are sets of knitted-on needles and missed needles, so that, for instance and preferably, if the reinforcement is knitted on one of four needles of a course and floated over three needles, then four courses, or multiples of four courses of reinforcement member would be knitted in. The line is preferably of two to 8 courses, further preferably four or six courses wide when produced in a course wide direction. The reinforcement material may be an elastomeric thread, but is preferably a heat fusible or heat shrinkable thread. Alternatively combined threads of a heat fusible or shrinkable component together with elastomeric component may be used. To provide a line in a wale-wise direction, one or two or more needles may be programmed out in the wale-wise direction whilst knitting the fabric, so that there is provided a less extensible line in a wale-wise direction. The line is preferably two to eight wales or further preferably two to four wales wide when knitted in a wale-wise direction. By way of example, embodiments of the present invention will now be described with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a seat squab in accordance with the present invention, Figure 2 is a cross sectional view of a fabric and core, Figure 3 is a cross sectional view of an alternative form of fabric and core, Figure 4 is a scrap perspective view of a cross section of a fabric in accordance with the present invention, Figures 5A to E are stitch diagrams showing the formation of a course-wise fabric line as shown in Figure 4, and Figures 6A to D are stitch diagrams showing the formation of a wale-wise fabric line. Referring to Figure 1, this shows in perspective a seat squab being a typical upholstered three dimensional object in accordance with the present invention. The seat squab comprises a foam core 1 and a fabric outer 2. The fabric outer is shown broken away along the line 3 to reveal the core 1. The foam core or bun is often reinforced with a metal frame. The seat may be provided with a back in a known manner. It will further be appreciated that although there is described herein a vehicle seat, other upholstered products in three dimensions may be manufactured in accordance with the present invention. The cover 2 is knitted in three dimensions on a flat V-bed machine having independently operable needles. The fabric 2 is of double jersey knit. Because the fabric is knitted in one piece it fits tightly over the foam bun 1. Essentially the seat comprises a base portion 4 with a front portion 5 lying in a plane substantially at right angles to the plane of the base portion 4. A pair of side members one of which is shown at 6 lie substantially in parallel planes at right angles to both the base portion 4 and the front portion 5. The seat is completed by a back portion (not shown but lying substantially parallel to the front portion 5) and a base which preferably includes integrally knitted tubes through which rods can be inserted to retain the seat cover on the foam bun. Although the seat cover may be integrally knitted there is a danger that it may "shuffle" on the base 4 i.e. the seat cover may move over the surface of the base, and pucker or distort any pattern on the cover. The present invention, by providing a "tight line" in the fabric enables the production of an upholstered product which has a pleasing aesthetic appearance and which has the further advantage of resisting shuffling of the fabric on the foam bun. Formed integrally into the knitted fabric 2 is a tight line 7. The tight line 7 comprises a line in the fabric of less extensibility than the portion of the fabric on either side of or surrounding the line. When the fabric is stretched over the bun 1 the tight line does not stretch as much as the remaining portion of the fabric and where the fabric is bent over the edge between the planes of the portions 4 and 5 - i.e. over the edge indicated generally by 8 - the fabric pulls into the bun as is shown at 9 in Figure 1. The effect of the fabric cutting into the foam bun can be seen more clearly in Figure 2. In Figure 2 the fabric 10 is stretched over a core or foam bun 11. Where the fabric passes over an edge (such as the edge 8 in Figure 1) the tight line such as tight line 12 does not stretch as much as the remainder of the fabric and this causes the fabric in the tight line to be stretched out of the general plane of the fabric towards the centre of the bun 11. The tight line is shown at 12 in Figure 2. The tight line will cut naturally into the foam to form a groove for the line. However for further anti-shuffling effect the foam bun may be preformed with a groove such as groove 13 as shown in Figure 3 so that the tight line 14 in the fabric 15 lies naturally in the groove 13 when the fabric is stretched over the foam core. This register between the tight line and the groove in the foam core of the seat aids assembly of the seat and further assists in an anti-shuffling effect for the fabric on the core. It will be appreciated that several tight lines may be produced in the fabric to assist in the anti-shuffling effect. The tight lines 7 may be produced by taking a knitted article and producing a seam of lock stitch on a sewing machine. However, although such a seam is easily produced, it does involve an additional machining operation over and above the knitting of the fabric over. It is preferred, therefore, that the tight line should be produced integrally with the knitting of the fabric cover which surrounds the tight line on both sides. The tight line may be produced by knitting-in, in a course-wise direction, a less extensible material than the yarn used to produce the fabric. As is shown in Figure 4 the knitted-in structurally reinforcing yarns 16 may produce the tight line effect in the fabric indicated generally by 17, which fabric is a double jersey knitted fabric. The knitting-in of the tight lines can be carried out by conventional equipment. Knitting techniques useful to the invention will be found in the following works of reference. "Knitting" by H Wignell, Published by Pitman 1971 Edition, London "An Introduction to Weft Knitting" by J. A. Smirfitt, Published by Merrow Technical Library, Watford, England, 1975. "Advanced Knitting Principles" Edited by C. Reichman, Published by National Knitted Outerwear Association, New York, New York, 1964. "Fully Fashioned Garment Manufacture" by R. W. Mills, Published by Cassell, London, 1965. and "Knitting Technology" by D.J. Spencer, Published by Pergamon Press, London, 1983. The knitting may be carried out on a flat bed machine such as:- a Stoll CMS Selectanit machine, for details see Knitting International, May 1990, pages 26-28, or a Steiger Electra 120FF machine, for details see Knitting International, April 1990, page 96, or a Shima Seiki SES machine, for details see Knitting International, September 1989, page 60. The process may be particularly adapted to produce a tight line by the knitting technique illustrated in Figures 5A to 5E. Figures 5A to 5D illustrate eight courses of fabric knitted on two sets of needles, an upper set along the line 20 and a lower set along the line 21. It will be seen that the upper set of needles 20 are numbered from 1 to 4 in two sequences. The reason for this will be noted below. In knitting the double jersey cover for the seat, the front face of the fabric i.e. the face seen by the purchaser of the seat is knitted on the lower row of needles 21. In this particular instance the face side of the fabric is knitted using a polyester yarn 22. The polyester yarn 22 is knitted on all of the needles 21 in the first course of the tight line structure shown in Figure 5A. On the reverse side of the fabric, however, a contractile thread formed of a low melting point nylon (or low melting point polypropylene) is knitted only on the first needles labelled needles number 1. This contractile thread 23 is therefore knitted on the number 1 needles in each group of four and floats over needles 2,3 and 4 to be picked up again on needle 1. This sequence continues across the entire width of the fabric being knitted. A typical knitted fabric for a vehicle seat cover would use many hundreds of needles and to produce the tight line the first course of the line would knit on every fourth needle. The next course to be knitted is shown in Figure 5B. Again the polyester yarn 24 is knitted on all of the line of needles 21 producing the front face of the fabric. This time, however, the contractile thread 25 is knitted only on each number 2 needle in the line of needles 20. The thread is then floated over needles 3,4 and 1 after knitting on needle 2, to be picked up on a second needle 2 as is shown in Figure 5B. Again this takes place throughout the entire width of the fabric in which the tight line is being knitted. In Figure 5C it can be seen that the contractile thread 26 is picked up on only the third in the set of four needles in line 20, whereas the polyester yarn 27 is again knitted on all of the needles of the front face 21. Finally, in the fourth course of threads the contractile thread 28 is knitted on the fourth set of needles and the thread is then floated over needles 1,2 and 3 as can clearly be seen in Figure 5D. Once again the polyester yarn 29 is knitted on all of the needles in row 21 to produce the front face of the fabric. Figure 5E is a compendium of the Figures 5A to D, and it can be seen that each of the row of needles 20 forming the back fabric of the fabric is knitted on in every fourth row whereas the front face needles 21 are knitted continuously. It can be seen, therefore, that the contractile threads are held on every fourth needle but in between the fourth needle they float. Thus after knitting the threads are able, on steaming and shrinking, to shrink down to form a tight line in the fabric to produce the desired effect once the fabric is stretched over the foam bun. This produces a tight line in a course-wise direction in the fabric. To produce a tight line in a wale-wise direction, the knitting sequence illustrated by means of the stitch diagrams Figures 6A to 6D are used. The wale-wise direction tight line is produced by the repetition of a four course knitting sequence. Thus, Figures 6A and 6B are repeated, and Figures 6C and 6D show this repeat occurring. In Figure 6A the needles shown in line 30 correspond to the rear needles producing the rear of the fabric. The needles in row 31 correspond to the front needles producing the front of the fabric. To the left of the diagonal line 32 the structure knitted on needles 30 and 31 is a "bird's-eye backed" ground structure of conventional type. Similarly, to the right of diagonal line 33, again there is knitted the "bird's-eye backed" ground structure. Between the lines 32 and 33 is knitted the two needle wide sequence which produces the wale-wise tight line structure. The polyester yarn 34 is knitted on needle 35 but is then floated across needle 36 to knit again on needle 37. Similarly, the polyester yarn 38 is floated across needle 39 but is knitted on needle 40 on the front of the fabric. In the next course as shown in Figure 6B the thread 34 is knitted on needle 36 but is floated over needle 35. Similarly, the thread 38 is knitted on needle 39 but is floated over needle 40. This two needle wide sequence on courses shown in Figures 6A and 6B is continuously repeated as shown in Figure 6C and 6D which represent the next four courses knitted. It can be seen that the knitting structure shown in Figure 6C is the same between the lines 32 and 33 as is the structure in Figure 6A, and the structure in Figure 6D is the same between lines 32 and 33 as the structure in Figure 6B. This two needle wide sequence is repeated in two course repetition for as long as is required to make the wale-wise tight line. Because there are less loops in the structure between the lines 32 and 33, the structure between those lines is less extensible under stress as there is less yarn length to deform between the lines. The structure shown in Figures 6A to 6D therefore produces a "tight line" structure which is in a wale-wise direction as the structure is built up in a wale-wise direction by repeated knitting of courses with the floated stitches as illustrated. It can be seen therefore that the "tight line" structure can be produced in either the course-wise direction or in the wale-wise direction. If it is required to produce a tight line at an angle to the line of courses - for example at an angle of 45° then the structure illustrated in Figures 6A to 6D could be used but the floated stitches would be moved one needle to the right or the left for each course to produce the inclined "tight line" structure.

Claims: An upholstered three dimensional structure incorporating an internal core (1, 11,) having at least one edge (8) and a knitted fabric cover (2, 10, 15) overlying said core (1, 11), characterised in that there is provided in the cover a line (7, 12, 14) along which the fabric is less extensible compared to the surrounding fabric, the line being positioned on the fabric such that the line curves over the edge (8) of the underlying core (1, 11,) so that on stretching the fabric over the core the less extensible line (7, 12, 14) is displaced from the general plane of the fabric towards the core. A structure as claimed in claim 1, characterised in that the core (1) is a foam bun. A structure as claimed in claim 1 or 2, characterised in that the line (14) engages a recess (13) in the core or cuts into the core. A structure as claimed in any one of claims 1 to 3, characterised in that the upholstered structure is a seat or part of a seat such as a squab or back. A structure as claimed in any one of claims 1 to 4, characterised in that the line (7, 12, 14) is formed by knitting the fabric cover such that it is less extensible along the line by virtue of the number, density or type of stitches used. A structure as claimed in any one of claims 1 to 5, characterised in that at least one reinforcement member (16) is knitted into the fabric along the line. A structure as claimed in claim 6, characterised in that the reinforcement member (16) is of a material inherently less extensible than the fabric on knitting. A structure as claimed in claim 6, characterised in that the reinforcement member (16) is treated after knitting to form the line. A structure as claimed in claim 8, characterised in that the treatment is heat treatment. A structure as claimed in any one of claims 1 to 9, characterised in that the fabric (2, 10, 15) is knitted on a flat V-bed machine having independently operable needles. A structure as claimed in claim 10, characterised in that the fabric is double jersey fabric (17). A structure as claimed in any one of claims 6 to 9, characterised in that the reinforcement member (16) is knitted in or inlayed in a course-wise direction. A structure as claimed in claim 12, characterised in that the reinforcement member (16) is knitted on the rear needles (30) only of a flat V-bed knitting machine. A structure as claimed in claim 13, characterised in that the reinforcement member (23 to 28) is knitted on only every second, third, fourth, fifth or sixth needle, the reinforcement member (23 to 28) being floated over the vacant needles between the beds (20, 21) and therefore between the front and rear of the fabric. A structure as claimed in any one of claims 12 to 13, characterised in that there is a plurality of reinforcement members, each course of reinforcement members picking up the next adjacent needle to the previous course. A structure as claimed in claim 14, characterised in that there are as many courses as there are sets of knitted-on needles and missed needles. A structure as claimed in claim 16, characterised in that the line is two to eight courses, preferably four to six courses wide when produced in a course-wise direction. A structure as claimed in any one of claims 12 to 17, characterised in that the reinforcement member is an elastomeric thread or a heat-fusible or heat-shrinkable thread. A structure as claimed in any one of claims 1 to 18, characterised in that there is provided a line in a wale-wise direction, one or two or more needles not being knitted on in the wale-wise direction whilst knitting the fabric, so that there is provided a less extensible line in a wale-wise direction. A structure as claimed in claim 19, characterised in that the line is two to eight wales, or preferably two to four wales,wide when knitted in a wale-wise direction.

Inventors: BROOKS VINCENT LEE, DAY GERALD FRANCIS, GREGORY GILES TIMOTHY, TRAYWICK ALBERT LEON, BROOKS, VINCENT LEE, DAY, GERALD FRANCIS, GREGORY, GILES TIMOTHY, TRAYWICK, ALBERT LEON
Applicants: GEN MOTORS CORP, GENERAL MOTORS CORPORATION
Application year: 1992
Main classification: D04B1
IPC codes: D04B1, B68G7, D04B21