GB2364634A

GB2364634A - Automotive seat cushion

Info

Publication number: GB2364634A
Application number: GB0119692A
Authority: GB
Inventors: Masatsugu Saito
Original assignee: Ikeda Bussan Co Ltd
Current assignee: Ikeda Corp
Priority date: 1999-10-22
Filing date: 2000-10-20
Publication date: 2002-02-06
Also published as: GB0025773D0; GB2355401A; JP3570497B2; JP2001204576A; GB0119692D0; GB2355401B

Abstract

For providing the occupant of an automotive seat with comfortable sitting, an improvement is applied to a cushion body 100B made of a foamed polyurethane and mounted on a seat frame 12. The cushion body 100B includes raised side portions 16 a main portion 14 by which hip and femur portions of a seat occupant are to be substantially supported. Two grooves 18 are provided in opposite sides of the main portion 14 and face an inner surface of the seat frame 12. For more comfortable sitting, softer pad member 20 of foamed polyurethane are installed in the grooves 18. Furthermore, the pad members may be put in air bags 24 connected by tubes 26 to valves 28.

Description

<Desc/Clms Page number 1> AUTOMOTIVE SEAT The present invention relates to seats, and more particularly to automotive seats of a type that comprises a seat frame and a cushion body held by the seat frame. More specifically, the present invention is concerned with automotive seats of a type that provides a seat occupant with comfortable sitting.

Hitherto, various types of seats have been proposed and put into practical use, particularly in the field of motor vehicles. For providing seat occupants with a comfortable sitting, some of them have made an improvement in the construction of the cushion body, which is, for example, usage of a softer cushion, usage of a somewhat harder cushion, usage of a cushion made of foamed polyurethane or the like, etc., However, hitherto, in considering the construction of the cushion body, the cause of fatigue inevitably applied to the hip and femur portions of a seat occupant when he or she is sitting on the seat for long time has been given only a little thought.

It is therefore an object of the present invention to provide an automotive seat which is constructed by putting the cause of fatigue upon long sitting into consideration.

According to a -f irst aspect of the present invention, there is provided an automotive seat which comprises a seat frame; a cushion body made of a foamed polyurethane and mounted on the seat frame, the cushion body including a main portion by which hip and femur portions of a seat occupant are to be substantially supported and a pair of raised side portions which are integrally formed on lateral sides of the main portion; two grooves respectively formed in laterally opposed sides of the main portion of the cushion body, each groove facing to an inner surface of the seat frame; and two flexible pad members made of foamed polyurethane and respectively and intimately put in the grooves, the pad members having a lower value in modulus of elasticity than that of the main portion of the cushion body.

According to a second aspect of the present invention, there is provided an automotive seat which comprises a seat frame; a cushion body made of a foamed polyurethane and mounted on the seat frame, the cushion body including a main portion by which hip and femur portions of a seat occupant are to be substantially supported and a pair of raised side portions which are integrally formed on lateral sides of the main portion; two grooves respectively formed in laterally opposed sides of the main portion of the cushion body, each groove facing to an inner surface of the seat frame; two flexible pad members made of foamed polyurethane and respectively and intimately put in the grooves, the pad members having a lower value in modulus of elasticity than that of the main portion of the cushion body; two air bags that contain therein the flexible pad members and are intimately installed in the grooves; two tubes respectively extending from the two air bags; and two valves operatively connected to the tubes respectively.

In the accompanying drawings; Fig. 1 is a perspective view of a cushion body used in an automotive seat of a first embodiment,

Fig. 2 is a front left sectional view of the cushion body of the first embodiment; Fig. 3 is a left bottom view of the cushion body of the first embodiment; Fig. 4 is a sectional view of the cushion body of the first embodiment under a compression test; Fig. 5 is a view similar to Fig. 4, but showing various zones where certain compression appears under the compression test; Fig. 6 is a view similar to Fig. 4, but showing a cushion body used in an automotive seat of a second embodiment, & ccoi ctl'nq to

Fig. 7 is a view similar to Fig. 6, but showing various zones where certain compression appears under a compression test; Fig. 8 is a perspective bottom view of a cushion body used in an automotive seat of a third embodiment not invention;

Fig. 9 is an enlarged sectional view of an essential portion of the cushion body of the third embodiment; Fig. 10 is an enlarged bottom view of the essential portion of the cushion body of the third embodiment; Fig. 11 is a plan view of a cushion body for showing a drawback that would be produced when the feature of the third embodiment is not provided; Fig. 12 is a sectional view of the cushion body for showing the drawback; Fig. 13 is a view similar to Fig. 4, but showing a cushion body used in an automotive seat of a fourth embodiment,

Fig. 14 is a schematic perspective view of a human body, showing a tuber ischiadicum and its associated bones in the

human body; Fig. 15 is a front right sectional view of a cushion body of a conventional automotive seat with the hip portion of the human body being put on the cushion body; Fig. 16 is a sectional view of another conventional seat in a condition wherein no external force is applied to a cushion body of the same; Fig. 17 is a view similar to Fig. 16, but showing a condition wherein a certain force is applied to the cushion body due to sitting of a seat occupant thereon; and Fig. 18 is a view similar to Fig. 17, but showing zones where remarked compression appears due to sitting of the seat occupant on the cushion body.

Before describing the detail of the present invention, consideration will be commenced on the cause of the fatigue that is inevitably applied to a seat occupant when he or she is sitting on a seat for a long time due to long driving or the like.

In Fig. 14, there is schematically shown a human body H (viz., seat occupant) taking a posture to sit on an automotive seat (not shown). Designated by TI is a tuber ischiadicum positioned in a hip portion HP of the human body H. As will be seen from Fig. 11, two tuber ischiadica TI are present in the hip portion HP.

Referring back to Fig. 14, a backbone BB extends upward from a united portion of the two tuber ischiadica TI and a pair of femurs F (only one is shown) extend forward from the tuber ischiadica TI through respective greater trochanters GT.

In Fig. 15, there is shown a front right sectional view of a cushion body CB of the seat in a condition wherein the hip portion HP of the seat occupant H is properly received on the cushion body CB. The cushion body CB comprises a major center portion CBA and raised side portions CBB (only one is shown by solid line) which are integrally formed on lateral sides of the major center

portion CBA.

As will be understood from these drawings, when the seat occupant H sits on the seat, that is, on the cushion body CB, the musculus gluteus located below the tuber ischiadicum TI, the femurs F and the greater trochanters GT is compressed by a certain degree. Thus, if the seat occupant H keeps his or her sitting posture for a long time, a so-called blood flow obstruction tends to occur in the musculus gluteus, which brings about the fatigue of hip portion HP and that of the femur portions.

The cause of the fatigue will become much apparent from the following description.

In Fig. 16, there is shown a sectional view of a seat 100. The seat 100 comprises a seat frame 102 and a cushion body 104 mounted thereon. Although not shown in the drawings, outer surfaces of the cushion body 104 are covered with a decorative outer skin. The cushion body 104 is made of a foamed polyurethane and comprises a main portion 106 which is sized and arranged to support thereon hip and femur portions of a seat occupant (not shown), and a pair of raised side portions 108 (only left one is shown) which are integrally formed at lateral sides of the main portion 106, as shown.

In order to examine how the cushion body 104 is compressed and behaves when a seat occupant H sits on the same, the seat 100 was subjected to a compression test by using a pressing block that is shaped like a hip of human body. That is, in the test, the hip-shaped pressing block was pressed against the cushion body 104 with a certain pressing force corresponding to the weight of the upper half of the seat occupant H.

The test results were represented by a pressure distribution pattern, which is shown in Figs. 17 and 18. In the pattern of Fig. 18, zones where remarked compression appeared are painted out. The zone Z1 where over 50% compression appeared is painted out with black. From the highly compressed zone Z1, other zones Z2

and Z3 extend continuously toward the center of the cushion body 104, where over 45% compression and over 40% compression appeared respectively.

From the pressure distribution pattern of Fig. 18, it is understood that the maximally compressed zone Z1 is placed just below the greater trochanter GT of a seat occupant H and the zone Z1 appears near the upper surface of the cushion body 104.

From the above, it becomes known that the highly compressed zone Z1, that is positioned below the greater trochanter GT and appears near the upper surface of the cushion body 104, would bring about a hard pressure against the musculus gluteus of the seat occupant H,thereby causing remarkable fatigue of the hip portion HP and femur portions of the seat occupant H.

In order to suppress or at least minimize the above- mentioned drawbacks, the inventor has thought out a unique idea by which the highly compressed zone Z1 is shifted away from the above-mentioned undesired position.

In the following, embodiments wi I I be described in detail with reference to the drawings.

Referring to Figs. 1 to 5, particularly Figs. 1 to 3, there is shown an automotive seat 100A of a first embodiment/ not the invention.

As is seen from Figs. 4 and 5, the automotive seat 100A comprises a seat frame 12 and a cushion body 10A mounted on the seat frame 12. Although not shown in the drawings, the cushion body 10A is covered with a decorative outer skin member. The seat frame 12 may be of a pan type or a type having cushion springs.

The cushion body 10A is constructed of a foamed plastic such as a foamed polyurethane or the like and comprises generally a main portion 14 which is sized to support thereon a hip portion HP (see Fig. 14) and femur portions of the seat occupant H and a

pair of side portions 16 which are arranged at both sides of the main portion 14. It is to be noted that the seat occupant H mentioned herein is a person having an averaged conformation.

As is seen from Fig. 4, each side portion 16 is raised a little from the side of the main portion 14 together with the seat frame 12.

As is best seen from Figs. 3 and 4, the cushion body 10A is formed at laterally opposed sides of the main portion 14 thereof with respective grooves 18 each extending in a fore-and-aft direction with respect to the seat 100A and facing downward, that is, toward an inner surface of the seat frame 12. As is seen from Fig. 3, each groove 18 has axially opposed ends which are closed. The grooves 18 are respectively positioned so as to be located below the greater trochanters GT of a seat occupant H sitting on the seat 100A. Usually, in persons having the averaged conformation, the distance between the two greater trochanters GT is generally the same.

Fig. 1, the distance L1 between the two grooves 18 is about 220mm to 280mm, preferably 250mm, which is the distance between the two greater trochanters GT of the physically averaged person H. When the distance L1 is smaller than 220mm, the supporting performance of the cushion body 10A may become poor, and when the distance L1 is greater than 280mm, the pressure applied to the lower portion of the greater trochanters may become remarkable.

Figs. 2 and 3, the width L2 of each groove 18 is about 20mm to 40mm, preferably 30mm.

Furthermore,

, Fig. 1, the length (L3 + L4) of each groove 18 is about 70mm to 290mm, preferably 180mm. More specifically, the length L3 between the front end of the groove 18 and an imaginary line HPL that extends laterally through a hip point HPT (viz., the point through which an extension of the backbone BB extends) of the cushion body 10A is about 30mm to

170mm, preferably 90mm, and the distance L4 between the rear end of the groove 18 and the imaginary line HPL is about 40mm to 120mm, preferably 60mm. When the length L3 is smaller than 30mm, uncomfortable slippage of the seat occupant's hip portion HP tends to occur, and when the length L3 is greater than 170mm, supporting performance of the cushion body 10A to the seat occupant's femur portions becomes poor. Furthermore, when the length L4 is smaller than 40mm, the pressure applied to the musculus gluteus maximus of the seat occupant H becomes remarkable, and when the length L4 is greater than 120mm, the cushion body 10A tends to have creases lowering the aesthetic value thereof.

As is seen from Fig. 2, each side of the main portion 14 where the groove 18 is provided has a thickness L6 that is about 30% to 60% of the thickness L5 of the main portion 14.

When the cushion body 10A of the first embodiment was subjected to the above-mentioned compression test, such a pressure distribution pattern as shown in Fig. 5 was obtained. As is seen from this pattern, the zones Z1, Z2,and Z3, particularly, the highly compressed zone Z1 is positioned away from the undesired position that would bring about the fatigue of the hip portion HP and femur portions of the seat occupant H.

Thus, in the automotive seat 100A of the first embodiment using the cushion body 10A, the pressure applied to the musculus gluteus of the seat occupant H is softened and thus the fatigue applied to the hip portion HP and femur portions of the seat occupant H can be reduced or minimized.

Referring to Figs. 6 and 7, there is shown an automotive seat 100B of a second embodiment,

invention. Since the automotive seat 100B of this second embodiment is similar in construction to the above-mentioned seat 100A of the first embodiment, only parts and portions which are different from those of the first embodiment will be described in the following.

As is seen from the drawings, in the second embodiment 100B, flexible pad members 20 made of foamed polyurethane are intimately put in the grooves 18. The flexible material for the pad members 20 has a lower value in modulus of elasticity than that for the main portion 14 of the cushion body 10B. Each pad member 20 may be used as an insert when the cushion body lOB is molded. That is, an integral molding may be used for producing a unit which includes the cushion body 10B and the pad members 20.

Furthermore, in the second embodiment 10013, the length (L3 + L4) (see Fig. 1) of each groove 18 is about 90mm to 210mm, preferably 150mm. More specifically, the length L3 is about 60mm to 120mm, preferably 90mm, and the length L4 is about 30mm to 90mm, preferably 60mm. Furthermore, the thickness L6 is about 30% to 60% of the thickness L5 of the main portion 14.

When the cushion body 1013 of the second embodiment 10013 was subjected to the compression test, such a pressure distribution pattern as shown in Fig. 7 was obtained. As is seen from this pattern, like in the above-mentioned first embodiment 100A, the highly compressed zone Z1 is positioned away from the undesired position that would bring about the fatigue of the hip portion HP and femur portions of the seat occupant H. Thus, also in the automotive seat 100B of the second embodiment, the fatigue applied to the hip portion HP and femur portions of the seat occupant H can be reduced or minimized like in the first embodiment 100A.

Referring to Figs. 8 to 12, particularly Figs. 8 to 10, there is shown an automotive seat 100C of a third embodiment,

invention.

As is seen from Figs. 8, 9 and 10, in the third embodiment 100C, the main portion 14 of the cushion body 10C is formed at its bottom side with a sector recess 22. The sector recess 22 comprises a triangular portion 22a and a crescent portion 22b. The sector recess 22 is positioned in front of the hip point HPT of

the cushion body 10C by a distance of L7 that is about 70mm to 90mm. As shown, the base point BP of the sector recess 22 is directed toward the hip point HPT. The angle of the base point BP is about 30 to about 90 . When the angle of the base point BP is greater than 90 , the supporting performance of the cushion body 10C to the femur portions of the seat occupant H becomes poor, and when the angle of the base point BP is smaller than 30 , the seat occupant H is enforced to feel a hard thing at his or her crotch portion.

As is seen from Fig. 10, the width L8 of the sector recess 22 is about 70mm to 80mm, and the longitudinal length L9 of the recess 22 is about 70mm to 110mm, preferably 90mm. More specifically, the axial length L92 of the triangular portion 22a of the recess 22 is about 30mm to 50mm, preferably 40mm, and the axial length L91 of the crescent portion 22b is about 40mm to 60mm, preferably 50mm.

As is seen from Fig. 9, the thickness L10 of the main portion 14 at the area where the sector recess 22 is provided is about 20mm to 50mm.

Due to provision of the sector recess 22, upon sitting on the seat 100C, the main portion 14 of the cushion body 10C can provide the seat occupant H with a soft feeling at his or her crotch portion.

This advantageous feature will be well understood from Figs. 11 and 12. That is, if the cushion body CB is not provided with means that corresponds to the sector recess 22, the center portion CP of the cushion body CB would be raised by a certain degree when the hip portion HP of the seat occupant His put on the seat as is shown in Fig. 12. In this case, the raised center portion CP makes the seat occupant H uncomfortable.

If desired, the sector recess 22 may be replaced with other recesses having different shapes, such as circular, oval, rectangular and so on.

Referring to Fig. 13, there is shown an automotive seat 100D of a fourth embodiment/

invention.

Since the automotive seat 100D of this fourth embodiment is similar to the seat 100B of above-mentioned second embodiment, only parts and portions which are different from those of the second embodiment 100B will be described in the following.

As is seen from Fig. 13, in this fourth embodiment 100D, each flexible pad member 20 is put in an air bag 24 from which a tube 26 extends outward. A manual valve 28 is connected to the tube 26, which is usually closed. The air bag 24 may be fixed to the seat frame 22 or the main portion 14 of the cushion body 10D.

When a seat occupant H sits on the seat 100D, the pressure in the air bag 24 is increased. Upon this, the seat occupant H slightly opens the valve 28. With this, the air in the air bag 24 is slowly discharged lowering the elasticity of the area of the cushion body 10D where the air bag 24 is provided. During this, the flexible pad member 20 reduces its volume gradually. When, upon sensing a desirable elasticity of that area, the seat occupant H closes the valve 28, the desirable elasticity of the area is kept unchanged during his or her sitting on the seat 100D and thus provides the seat occupant H with a comfortable sitting. When the seat occupant H opens the valve 28 and removes from the seat 100D, the air bag 24 is returned to its original expanded state due to a returning expansion of the flexible pad member 20.

If desired, the valve 28 may be replaced with an electromagnetic valve controlled by sensors through a controller. That is, when the sensors sense the sitting of the seat occupant H sits on the seat 100D and the weight of the upper half of the seat occupant H, the controller opens the valve for a time determined by the sensed weight. With this, the desirable elasticity of the area of the cushion body 10D is automatically set when the seat occupant H sits on the seat 100D.

Various modifications may be carried out by those skilled in the art, in light of the above descriptions. In particular, a feature of any one embodiment may be incorporated in any other of the embodiments.

Claims

GLAIM5 1. An automotive seat comprising: a seat frame; a cushion body made of foamed polyurethane and mounted on said seat frame, said cushion body including a main portion by which hip and femur portions of a seat occupant are to be substantially supported and a pair of raised side portions which are integrally formed on lateral sides of said main portion; two grooves respectively formed in laterally opposed sides of said main portion of the cushion body, each groove facing an inner surface of said seat frame; and two flexible pad members made of foamed polyurethane and respectively and intimately put in said grooves, the pad members having a lower value in modulus of elasticity than that of the main portion of the cushion body.
2. An automotive seat comprising: a seat frame; a cushion body made of foamed polyurethane and mounted on said seat frame, said cushion body including a main portion by which hip and femur portions of a seat occupant are to be substantially supported and a pair of raised side portions which are integrally formed on lateral sides of said main portion; two grooves respectively formed in laterally opposed sides of said main portion of the cushion body, each groove facing an inner surface of said seat frame; two flexible pad members made of foamed polyurethane and respectively and intimately put in said grooves, the pad members having a lower value in modulus of elasticity than that of the main portion of the cushion body;

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two air bags that contain therein said flexible pad members and are intimately installed in said grooves; two tubes respectively extending from said two air bags; and two valves operatively connected to said tubes respectively.
3. An automotive seat as claimed in claim 1 or 2, in which each of said grooves extends in a fore-and-aft direction with respect to said cushion body.
4. An automotive seat as claimed in claim 3, in which the length of each groove is approximately 70 mm to approximately 290 mm.
5. An automotive seat as claimed in any preceding claim, in which each lateral side of said main portion of said cushion body wherein the groove is provided has a thickness that is approximately 30% to 60% of the thickness of the remainder of said main portion.