GB2232078A

GB2232078A - Adjustable vehicle seat

Info

Publication number: GB2232078A
Application number: GB9009346A
Authority: GB
Inventors: Hiroshi Sekido; Tadashi Sakuma; Toshimichi Hioki
Original assignee: Okamoto Industries Inc
Current assignee: Okamoto Industries Inc
Priority date: 1989-04-28
Filing date: 1990-04-26
Publication date: 1990-12-05
Anticipated expiration: 2010-04-26
Also published as: GB9212246D0; JPH0513634Y2; KR900015977A; GB2232078B; GB2255905B; GB2255905A; KR940000035B1; GB9009346D0; JPH02142329U; GB9214046D0

Abstract

An automatic vehicle seat capable of adjusting each region is characterized in the use of air bags stacked multiply as a substitute for a hydraulic cylinder in the conventional art, the vehicle seat of the invention consists of a twice-folded type seat back with a head-rest pad on the top, a thigh-support capable of changing the gradient and position, side-supports provided on the both sides of seat portion and seat back in which capable of adjusting the inclinations respectively, an elevation mechanism capable of rising and descending the seat level preferably accompanied with an automatic locking device, a mobility mechanism capable of forwarding and backing the seat position with an automatic locking device, wherein these mechanisms are driven by the expansion and contraction of various type air bags arranged with each mechanism. <IMAGE>

Description

VEHICLE SEAT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a vehicle seat, more particularly to an improved vehicle seat equipped with an automatic adjustment mechanism capable of adjusting and controlling the height of seat level, the gradient of head-rest portion on the seat back, the thigh-support of seat portion, the mobility of seat body in the longitudinal direction and the like to an optimized position and gradient respectively according to the seat occupant's preference.

2. Description of the Prior Art Conventionally in the art, it is known that there are various types of vehicle seat having automatic mechanisms such as the inflating mechanism of seat contours, the elevating mechanism of seat level, the mobilizing mechanism of seat body in longitudinal direction and the like, and these mechanisms are mainly driven by utilizing the stroke of cylinder such as a hydraulic cylinder, an air cylinder, a motor-drive cylinder and the like under a remote control from dashboard, particularly it is noted that the inflating mechanism of seat contour consists of an inflatable air bag which is housed within the cushion of seat contour and actuated by a pneumatic means.So far as the air bag is concerned, there is no prior art to substitute the stroke of air bag for the stroke of cylinders as mentioned above so that the air bag is limited to be used for only the inflation of seat contours.

However, it is known that the above conventional type automatic vehicle seats are not always popularized because of the higher cost of production accompanied with expensive drive-sources such as the cylinders and their pumps with motors. In addition, the total weight of the above mechanism is not negligible for the requirement of reducing the car weight as the needs of the times in view of the energy conservation.As another disadvantage of the conventional, it is also known that a seat occupant is not always comfortable while sitting on the seat when these cylinders are driven to thrust out their contour pads outwardly or to change their position excessively because such the mechanical change of seat contours or seat position lucks one more softness with respect to the configuration between the changed seat contour or seat position and the occupant's body due to a metallic construction of those mechanisms without any cushion itself.In review of the conventional type prior art, it is found that some of them is not equipped with a complete stopper system to fix the seat body at the changed position by locking the stopper of the seat body automatically in response to the change position of seat body, and then it is presumable that it may be often removed by an external cause such as the sudden stop of car, a car crush and the like, thus it should have a serious problem in the safety of vehicle seat.

SUMMARY OF THE INVENTION Accordingly, a general object of the present invention is to provide an automatic vehicle seat capable of controlling the position or gradient of each portion of vehicle seat separately in which are driven by substituting air bags for air cylinders.

A more specific object of the present invention is to provide a reciprocation mechanism to atomatize the movement of each portion of vehicle seat in which consists of a plurality of air bags stacked multiply between a basement and an actuating plate of transmitting the stroke of air bags' reciprocation to an object as a substitute for a conventional type air cylinder.

Another object of the present invention is to provide a separate type seat back with a head-rest, an elevation type seat portion with a thigh-support and a mobilizing mechanism to move the seat body in longitudinal direction in which are driven by the above air bags reciprocation respectively.

Further object of the present invention is to provide an improved type vehicle seat assembly equipped with an automatic mechanism capable of remotely controlling the each portion of vehicle seat with a minimized production cost and light weight as an additional attachment.

In accomplishing these objects, in one aspect of the invention, it provides a separate type seat back with a head-rest on the top of seat back portion, the upper half portion of seat back with the head-rest is made to bow slightly toward front direction from the separated place, the upper half seat back portion and the lower seat back portion are jointed each other by the first hinge positioned between the upper half portion and the lower seat back portion, the head-rest portion is jointed with the top of upper half portion by the second hinge positioned between the top of upper half portion of seat back and the bottom of head-rest, wherein not only the upper half portion of seat back with the head-rest is made to bow slightly toward front direction by means of the first hinge but also the head-rest portion itself is made to bow slightly toward the same direction by means of the second hinge. In the bowing mechanisms of these two portions, the bowing movements of them are performed by dogleg shaped lever, exactly they are made of doglegged metallic plates having a width corresponding to the width of seat back, which are jointed coaxially with the hinge shaft and the upper portion of lever plate is fixed with the rear side interior wall of the upper half portion of seat back and the other portion of lever plate is positioned free in a box shaped hollow space provided within the thickness of the lower portion of seat back wherein the upper half portion of seat back can be moved to bow slightly when the free end of lever plate in the space is pressed toward the rear side interior wall by the plurality of air bags which are stacked multiply between the free end of lever plate and the opposite basement as a front side interior wall of the box shaped space.According to the inflating movement of air bags, the free end of lever is pressed toward rear side and then the other half of lever fixed within the upper half portion of seat back is bowed toward front direction at the rate of doglegged angle. The aforementioned feature is the mechanism of bowing the upper half portion of seat back.

As the same aspect of the above, the second hinge is jointed coaxially with another dogleg shaped lever plate which the upper end portion of lever plate is fixed within the head-rest body and the other free end of lever plate is positioned in a box shaped hollow space provided within the thickness of the upper half portion of seat back. Another air bags are disposed between the free end of lever plate and the basement wall of space and then presses the free end of lever plate according to the inflating movement of air bags, consequently the head-rest portion is further bowed as well as the upper half portion of seat back.

Referring now in detail to the aspect of air bag system to be used in the present invention as a substitute for the conventional hydraulic cylinder, the single body of air bag consists of an almost square shaped bag which is made of a plurality of thermally plastic sheets having a high tensile strength wherein the plurality of sheets being laminated multiply and all the side peripheries of air bag are thermally welded to be sealed. As the final products of air bags, the plurality of air bags are further stacked multiply by joining their central portions each other face to face with a thermally welding means and a common opening passes through the central portions so as to communicate each other pneumatically within the plurality of air bags wherein they constitute a sort of bellow as a substitute for a cylinder when a compressed air is supplied into the air bags.This is the final aspect of air bags system.

In another aspect of the invention, it provides an elevation seat having a plurality of air bags disposed between the bottom of seat portion and a basement of the seat portion, the bottom of seat portion and the basement thereof are linked by a pair of X-shaped cross members with a stopper device consisting of a notch and a rack bar for supporting the seat portion securely in level according to the elevation operated by the expansion and/or contraction of air bags stacked multiply within the allowed space between the X-shaped cross members provided at both side of the bottom of seat portion along with the longitudinal direction, the air bags have an utmost surface area widen as much as possible to correspond with the interior surface area of the bottom of seat portion.According to this utmost wide surface area of air bags, the air bags can lift up the whole seat body together with the occupant easily by a minimized air pressure such as about 0.1 kg/cm2(1000mm H2O/cm2). As the basis of this pressure, supposing that now there is an air bag having the surface area of 929cm2(one foot square) and when the air pressure of 0.1 kg/cm2 would be supplied into the bag, the liftable load becomes 92.9 kg. If we revive this load by using an air cylinder having the inner diameter of 2.54cm(1 inch), the necessary air pressure should be at 18.36 kg/cm2 which may be beyond a normal air pressure used in the general industry. It can understand, therefore, that the 18.36 kg/cm2 of pressure may be in the region of hydraulic cylinder any way.In contrast, it is noted that such the lower pressure of 0.1 kg/cm2 can facilitate the air compressor mechanism, for example, it can employ even an oscillating type air compressor having a bellows made of a plastic material. From these discussions, it is understandable that how much the air bag system is suitable for the lifting mechanism in comparison with the conventional use of cylinder system so far as an automatic vehicle seat is concerned.

As a preferable attachment of the seat portion apart from the lifting mechanism, a thigh-support pad is provided at the front edge of seat portion and the thigh-support pad is adjusted automatically so as to move forward or backward by means of the expansion or contraction of air bags as a substitute for an air cylinder and the like.

In further aspect of the invention, it provides a mobilizing seat body which is moved forward or backward automatically in the longitudinal direction in response to a remote control from dashboard by the occupant.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 shows a longitudinal side view of a typical vehicle seat of the present invention employing several air bag systems as a substitute for an air cylinder, Fig.2 shows an enlarged longitudinal side view of the seat portion for explaining each position of inflated air bags stacked multiply, Fig.3 shows a partially enlarged longitudinal side view of seat back portion to detail an aspect of air bags expanded within a box shaped hollow space therein and then presses a dogleg shape lever toward the rear wall, Fig.4 and Fig.5 show transverse sectional views of the side supports provided in the both sides of seat back portion, Fig.6 shows a transverse sectional view of the side supports provided in the both sides of seat portion, Fig.7 shows a transverse top plan view of seat back portion, Fig.8 shows a vertical front view of the lower portion of seat, Fig.9 shows a partially broken side view of the elevation mechanism provided between a seat portion and a basement of the seat, Fig.10 shows a side view of a stopper portion consisting of a notch and rack bar for an elevation mechanism, Fig.11 shows a partially broken side view of the stopper portion with an actuator combined with air bags for an elevation mechanism, Fig.12 shows a vertical front view of a stopper for the mobility of seat body on a rail, Fig.13 shows a transverse top plan view of a stopper which is in state of engaging with a rack, Fig.14 is a schematic diagram for showing pneumatic system and control system, Fig.15 to Fig.18 are partly broken perspective illustrations for showing one example of air bags, Fig.19 is a partly broken schematic illustration for showing an air bag made of laminated sheets, Fig.20 is a partly broken perspective view of another example, Fig.21 and Fig.22 are enlarged section view for showing a head-rest portion, Fig.23 is a vertical side view for showing a seat body which has not any elevation mechanism and also mobilizing mechanism, Fig.24 is a vertical side view for showing the same seat body of Fig.23 when their air bags are inflated respectively, Fig.25 is a side view for showing a seat body with only an elevation mechanism, Fig.26 is a side view for showing the same seat body of Fig.25 when the seat is elevated, Fig.27 is a vertical front view for showing the same seat body of Fig.26, Fig.28 is a vertical side view for showing a seat body with only a mobilizing mechanism, Fig.29 is a vertical side view for showing the same seat body of Fig.28 when the seat body is mobilized, and Fig.30 is a side view for showing the same seat body of Fig.29.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In Fig.1 and Fig.3, a seat back portion(a) consists of a seat back body(1) and the rear board(2) of supporting the seat back body(1), and in Fig.3 the seat back portion(a) further consists of the upper half portion of seat back with a head-rest(b) and the lower half portion of seat back. As first, it is referred to an automatically adjustable mechanism to move the head-rest(b) according to Fig.3.

In the upper half portion, there is a box shape hollowed space, that is, an inner case(4), which is provided within the thickness of the upper half portion of seat back body(1), and the top and bottom of the inner case(4) are opened. A dogleg shaped lever plate(b2) for the upper half portion of seat back body(1) with the head-rest(b) is provided along with the interior rear walls of the inner case(4) and also another hollow space of the head-rest(b), wherein the upper portion of the dogleg shape lever plate(b2) is fixed with and formed to incorporate with the bottom basement of head-rest body(b1) and the other downward half plate(b2') thereof, which is much longer than the upper portion of the plate(b2) and then is free in the inner case(4) of the upper half portion of seat back body(1) by holding an air bags(11) with the free end thereof as shown in Fig.1.

The dogleg shape lever plate(b2) is formed to bend up the both side edge portion longitudinally along with the doglegged line shaped as a dustpan and the both side walls(b2")(b2") are formed to slope to fall toward the free end from the doglegged corner portion in order to reinforce the lever plate(b2).

In Fig.3, a pair of hinge shaft holes(9)(9) are provided at the doglegged corner portion of the both side walls(b2")(b2") of downward half plate(b2') to receive a hinge shaft(10) coaxially and the air bag system(11) for the head-rest(b) is assembled between the free end of the lever plate(b2) and a vertical interior wall(4a) of front side of the inner case(4) as a foundation when the air bags(11) are expanded by feeding a compressed air and then presses the lever plate(b2) toward the rear wall of case(4). In this feature, according to the expansion of the air bags system(11) for pressing the lever plate(b2), the head-rest body(b1) is inclined toward the front side to facilitate the positioning of occupant's head during his or her long distance drive as shown in Fig.3.In Fig.3, a pair of C-shaped spring(12) having an inward bias is provided between the bottom portion of the head-rest body(b1) and the top portion of the case(4) by fixing the each free end of spring(12) with the above both portions respectively so as to pull downward the head-rest body(b1) and make it to position upright unless the air bags(11) are actuated.

Nextly, it is further referred to one more same mechanism as the above to move the upper half portion of seat back body(1) by means of another mechanism composed in combination with a dogleg shaped lever plate and an air bags system which are housed within the lower half portion of seat back body(1).

In Fig.3, a box shaped hollow space(2a) is provided within the thickness of the lower half portion of seat back body(1) and an inner case(4') is housed within the hollowed space and the top portion of this hollowed space is opened to designate as an opening(1b). A dogleg shape lever plate(1d) is provided in which the upper half portion(1e) of the lever plate(1d) is inserted into the other hollowed space(1a) of the upper half portion of seat back body(1) and fixed with the interior rear wall(2d) of the hollowed space(1a) by means of screws(not shown in the drawings) and the like securely.The length of the upper half portion(1e) of the lever plate(1d) is required to be longer enough as well as the length of the other downward half portion(1d') in the nature of supporting the whole body of the upper half portion of seat back body(1) instead of the head-rest body(b1) previously and the free end of the downward half portion(1d') is positioned freely in the inner case(4'). The dogleg shape lever plate(1d) is formed to bend up the both side edge portions so as to shape as a dustpan and the both side walls(1d")(ld") are made to slope to fall toward the free end from the doglegged corner portion in order to reinforce the lever plate(1d).

In Fig.3, a pair of hinge shaft holes(3)(3) are provided at the each corner portion of the walls(1d")(1d") to receive a hinge shaft(5). On the other hand, a pair of hinge shaft brackets(2c)(2c) having hinge shaft holes(2c')(2c') are fixed with the both sides of the walls of hollowed space(2a) in the width direction, and also fixed on the top edge of the opening(2b) of the hollowed space(2a) outwardly from the both side walls(1d")(1d") of the dogleg shape lever plate(1d) which is inserted within the both side brackets(2c)(2c) to engage these shaft holes(3)(3)(2c')(2c') each other by passing through the shaft(5) into them, wherein an air bags system(6) is assembled between the downward half plate(1d') of the dogleg shape lever plate(ld) and the front side interior wall(4'a) of the inner case(4'), whereby the upper half portion of the seat back body(1) is moved toward the front direction when the air bags system(6) is expanded according to the occupant's preference. In the summary of the aforementioned aspects, this seat back body(1) of the present invention comprises two separate parts, that is, a twice-folded type seat back, such as the head-rest body(b1) portion and the upper half portion and they can change their gradients respectively according to the occupant's preference in which the air bag system is adoped as a substitute for the conventional hydraulic cylinder and the like.

In Fig.3, a pair of C-shaped springs(7) having an inward bias are provided between the bottom portion of the upper half portion of seat body(1) and the top portion of the opening(2b) by fixing the each free end of the spring(?) with the above both portions respectively so as to pull downward the upper half portion of seat back body(1) for making it to position upright unless the air bags system(6) are actuated. As the configuration of the seat back portion(a), it is basically positioned that the seat back portion(a) is fixed at the rear end of the seat portion(c) of the vehicle seat so as to recline or rise freely by utilizing an well known locking mechanism in the art.

In the modification of the above each aspect, it is referred to the adjustable gradient angle of the head-rest portion and the upper half portion of seat back. The inclining angle of them relates to the stroke distance of the downward half plate of lever plate reciprocating between both interior walls according to the expansion and contraction of air bag system, more particularly the inclining angle further relates to the size of inner case in the thickness direction of seat back body because the more the size of case is larger, the more the inclining angle becomes deeper, therefore, it may be modified to enlarge the size of inner case as well as the thickness of seat back body being increased.

In another modification, as to the basement walls(4'a)(4a) for receiving the expanded air bags as the opposite of lever plate, it is not always limited in the aforementioned aspect and admitted to modify it, for example, it can substitute an independent plate supported by an adequate number of arms extending from the rear side wall for the basement walls(4'a)(4a) of the front side of the case(4')(4).

Referring now in detail to the seat portion of the present invention. In Fig.2, in outline, this seat portion(C) consists of four functions such as an inclining mechanism of changing the gradient of seat portion(C), a thigh-support mechanism of reciprocating the thigh-support portion(15) at the front edge of seat portion(C) and further of changing the gradient of thighsupport portion(15), a lift mechanism of elevating the seat portion(C), and a mobilizing mechanism of the seat portion in the longitudinal direction on a car floor. The significance of the present invention is to use an air bag system as their drive sources of the above mechanisms as a substitute for a conventional hydraulic cylinder so that it is noted that this air bag system is utilized in various where in this seat portion.

In Fig.2, the seat portion(C) consists of a trim cover(103) with a cushion material(102) which forms a contour of the seat portion(C), a support plate(13) to support the seat contour(C), a pair of pivotal frames(13a)(13a) fixed with the bottom of the support plate(13) in the both side edge portions of the plate(13) and the rear end of the frames(13a)(13a) are pivoted at the rear end to constitute a hinges to pivot with a hinge brackets(not shown in the drawings) fixed on a cover case(C3) as an intermediate basement.An air bags system(16) is disposed between the lifting portion(13a) of the support plate(13) and the surface of the cover case(C3) to give a minor change of seat gradient upon the seat portion(C) according to the expansion and contraction of the air bags(16).

It is referred to the thigh-support mechanism. In Fig.2, this mechanism consists of the unit body(15') of the thighsupport portion(15), a trim cover sheet(103) with the cushion (102), a basement(15b"), an air bags system(16) for adjusting the gradient of thigh-support body(15), a pair of ram frames (15a)(15a) of the thigh-support body(15) with a bent free end portion(15b') and an upper plate portion(15a'), a stroke receiving plate(15a") fixed with the other free end of the ram frames(15a)(15a) vertically, the cover case(C3) fixed on the bottom plate(C2) arranged on the main frames(C1) and to house the aforementioned mechanisms of the thigh-support portion(15) with its back up mechanisms into the cover case(C3), a pair of groove rails(C5)(C5) having a concave shaped section to receive the ram frames(15a)(15a) slidably, and a front edge cover(C4) to cover the front opening portion of the cover case(C3). In addition, although this is not shown in the drawings, an adequate coil springs are stretched to pull each other between the basement(15b") of the thigh-support portion(15) and the bent free end portion(15b') of the ram frames(15a)(15a), and further between the stroke receiving plate(15a") of the ram frames(15a)(15a) and the rear wall of the cover case(C3).

These coil springs should be housed in their mechanisms respectively.

In Fig.7 and Fig.8, as an necessary attachment to back up the comfortability of the seat portion and the seat back portion, now it is referred to a sides support pads(d)(d) which are provided to hold the both sides of occupant's thigh portions in the seat and also to hold the occupant's sides in the seat back during the drive of car. In Fig.8, it shows the symmetry composition and mechanism of a pair of the side supports(d)(d) on the both sides of the seat portion(C).In Fig.6, the side support pads(d)(d) consists of the contour of the side support pads(d) for the seat portion(C), a hollowed space provided under the side support pads(d) to house an air bags syetm(20) arranged in combination with a dogleg shape lever plate(d2) having a pair of a sloped walls bent in upright at the both sides of the lever plate(d2), an outer board(d') with a trim cover sheet, a upper half portion(d1) of the doglegged lever plate(d2) to be fixed with the outer board(d') and to be risen together with the pad body(d) when the air bags system(20) is expanded between a basement wall(d3) of the hollowed space and the upper half portion(d1) of the lever plate(d2), and presses the other downward half portion(d2) of the doglegged lever plate(d2) outwardly, a pair of hinge shaft holes(18)(18) provided at the doglegged corner portion of the sloped walls of the lever plate(d2) to engage with a pair of hinge brackets(d4) having shaft holes respectively which are fixed on the outer vertical wall(d4) of the hollowed space by passing through a hinge shaft(19) into them. In Fig.4 and Fig.5, the other side support pads(d)(d) for the seat back(a) are shown with the same compositions and functions from Fig.6 so that a detailed explanation will be omitted. In addition, these side support pads(d)(d) are constantly pulled outward direction so as to be opened toward the upper direction by stretching a pair of pulling biased spring(not shown in the drawings) between the basement walls(d3)(d3) and a support plate (d2) so as to incline each side support outwardly.

Now it is referred to an elevation system of the seat body(A) equipped with an autimatic lifting mechanism by utilizing an air bag system as a substitute for the conventional hydraulic cylinder and the like. In Fig.1 and Fig.26, this elevation system of vehicle seat(A) comprising of an intermediate basement(21) provided to support the seat body(A) through a pair of X-shaped link mechanism with the air bag system, the pair of X-shaped link mechanism(22)(22) consisting of four pieces of bar members(22a)(22a) to make them to cross each other at their central position pivotally and then provided a pair of X-shaped bar members, a pivotal hole provided at the each free end of the bar member(22a), a pair of brackets(23)(23) having a pivotal holes are fixed commonly on the front end of the intermediate basement(21) and the front end of the bottom surface of the main frame(24) along with the longitudinal direction, another pair of brackets(23')(23') having a lateral slits(23a)(23a) are fixed commonly on the rear end of the intermediate basement(21) and the rear end of the bottom surface of the main frame(24) wherein the each free end of X-shaped bar members(22a) is pivoted with these brackets(23)(23)(23')(23') in order to constitute a link mechanism to keep the level of seat body(A) constantly according to the elevating movement of seat body(A) by means of the expansion and contraction of air bag system(28) which is assembled between the both link mechanisms. In the link motion of X-shaped link mechanism, the idle slits(23a)(23a) of the brackets(23')(23') are effective to make the pivoted portion of the free end of bar member(22a) in which corresponds to the each position of the idle slits(23a)(23a) to slide along within the slits(23a)(23a) according to the rising movement of the X-shaped link mechanism by the expansion of the air bags(28) due to the other free ends of the bar member(22a)(22a) being fixed pivotally with the brackets(23)(23).

As next, it is referred to a mobilizing mechanism of the above seat body(A) including the elevation system. In Fig.1 and Fig.12, it is further referred to in detail the structure of the main frames(24) which support the intermediate basement(21) of the aforementioned elevation mechanism.In brief, this mobilizing mechanism consists of four elements such as the main frames(24)(24) having a concave shape in cross section to engage with and slide on a rail by means of the reciprocation of air bags(29), a convex shaped rails(27)(27) combined with a rack rail(27a)(27a) in the outward directions from the each convex rail [in Fig.12 and Fig.13i to receive the concave shaped main frames(24)(24) by the convex rail portions with a suitable length corresponding to a span capable of moving the seat body(A) in range of a predetermined distance and also to engage a lock pin with the gear of the rack rail(27a) portion respectively as a stoppers which are actuated automatically by a exclusive type air bags(34) for locking device in synchronize with the mobility of the seat body(A), and two groups of air bags(29a)(29b) disposed in a space(Y) for mobility only which are separated by a partition plate provided between them(in Fig.1). In the detail of locking device, in Fig.12, the locking device includes an engaging lever plate(31') formed as L-shaped lever plate(31') which consists of a vertical lever plate portion(31') and a laterally bent lock pin portion(31b) including a plurality of lock pins(31b)[in Fig.13] formed at the free end of the laterally bent portion for engaging with the rack gears(27a) of the rack rail(27).A pair of pivotal brackets(31c) are fixed at the lower portion of the lever plate(31') in the both side edges in the width direction of the lever plate to engage the pivotal brackets(31c) with the opposed another pivotal brackets(35)(35) which are fixed with the concave shaped main frames(24) so as to put the plurality of lock pins portion(31b) between the opposed another pivotal brackets(35)(35) by passing through a shaft(36) into each hinge holes(31c')(31c')(35')(35') of the brackets. As the configuration of the engage lever plate(31'), it is arranged in parallel with an vertical wall(38) which is arranged to project from the side surface of the support base(37) fixed on the intermediate basement so as to cross at right angle against the rack rail(27a).An air bags system(34) for using this locking device is disposed in a space provided between the receiving surface(38') of the vertical wall(38) and the other receiving surface(31a) of the lever plate(31'). A pair of coil springs(39)(39) are arranged around the shaft(36) for biasing the engage lever plate(31') toward the receiving surface(38') of the vertical wall(38) constantly unless the air bag system(34) is expanded.

A pair of the convex shaped rails(27)(27) combined with the rack rail(27a)(27a) are further fixed on a pair of rail basements(26)(26) which are further more fixed on a pair of bottom basements(25)(25) fixed on the car floor(Z).

Relating to the above automatic locking mechanism for the mobility of seat body(A), it is further referred to one more another locking mechanism which is used exclusively for locking the seat level elevated by the elevation mechanism. As aware of already, the seat elevation also requires any locking device to stop the elevation of seat at a preferable position during the operation of the elevation mechanism. This is also indispensable as well as the stopper of seat mobility in view of a car driving security.

In Fig.9, Fig.10 and Fig.11, they show the seat level locking mechanism(17)(30)(33) which comprises a L-shaped lever(30) consisting of a vertical frame(30b) with a rack gears(30b') and a horizontal frame portion(30a) to receive at the bottom surface of the frame(30a) the expansion and contraction of an air bag system(33) to be purposed for the seat level locking mechanism only. The vertical frame(30b) is required to have a sufficient length including the rack gears portion capable of engaging the rack gears(30b') with a lock pin(17) projected from the rear end of the seat base frame.In Fig.27 and Fig.11, the right angle corner portion of the L-shaped lever(30) is pivoted rotatably between a U-shaped bracket(32) which is arranged to project from the rear end edge of the intermediate basement(21) of the seat body(A). According to the expansion and contraction of the air bags(33) disposed under the bottom surface of the horizontal frame(30a), the vertical frame(30b) performs a metronomic swing movement for disengaging and engaging the rack gears(30b') with the lock pin(17), wherein the seat elevation can be stopped at a preferable position.

In Fig.15 to Fig.19, it is referred to the composition of the air bag systems to be adopted in this invention. Fig.19 shows the essential composition of sheet material(40) of the air bag(40a)[Fig.15 to Fig.181, the sheet material(40) is a laminated sheet consisting of three layers, more particularly a net shaped core material(40') is sandwiched between two sheets (40")(40") in Fig.19. With respect to the net shaped core material, it is woven by a fiber and/or a filament having a non-expandable properties with a high tensile strength made of a synthetic resin such as a polyester resin, a polyamide resin and the like, The diameter of the fiber or filament is between 50 and 100 micron and the woven meshes are between 70 and 200 meshes per inch.This core material(40') is sandwiched between two sheets made of a polyurethane resin and the like having rather a slightly harder properties for a thermal plastic workability, thus they are laminated as a single sheet(40) by means of an well known process in the art.

Regarding the process for making the bag(40a), two sheet(40) (40) having a predetermined sizes are overlapped together and thermally welded along the periphery edges of them to form a sealed bag and a plurality of the sealed bags are stacked multiply and then they are further welded partially at around their body portions to connect them each other partially so as to form a bellows finally as shown in Fig.16. Before final welding process, an air communicating vents(41) are provided to pass through their welded body portions and also an air feeding tube(42)(46) is provided integrally with one edge of the air bag(40a). As the aspect of the multiply stacked air bags when the bags are inflated by a compressed air, such each portion which is not welded opens each other and shows a V-shaped valley between them. According to the use of such the type of laminated sheet, the air bag is given an excellent elasticity with a good tensile strength. As to the applicability of each air bag system into the present invention, the same air bag systems shown in Fig.15 may be applied for the head-rest air bags(11), the seat back controlling air bags(6) and the elevation mechanism air bags(28), another same air bag systems shown in Fig.16) may be applied for the thigh-support extrusion air bags(16) and the seat mobility air bag systems(29), further same air bag systems shown in Fig.17 may be applied for each the side-support air bag systems(20)(seat portion and seat back portion) and the both locking devices air bag systems(33)(34), and lastly the same air bag systems shown in Fig.18 may be applied for the seat gradient air bag(16) and the side-support air bag(20). In the modification of the above air bag systems, there may be not any restriction with respect to the welding process of bags, the number of stacking the bags and the like and then it is allowed to follow the space of arranging the air bags adequately.

Referring now in detail to the operation of each mechanism by using a centralized control panel(47) in Fig.14, this operation system consists of the centralized control panel(47), three positions type switch buttons(47a to 47h) arranged on the panel surface, a low pressure type compressor(43) with a DC motor driven by the car battery source, a compressed air distributing pipe line(44) with 12 branch lines, 12 pieces of three-way type solenoid valves(45a to 45L) and 12 sets of air bag system(29b),(29a),(34),(28),(33),(16),(16),(20),(20),(16), (20),(20),(11) and (6). These valves(29a) to (6) are wired with the control panel(47) respectively through each switch buttons(47a) to (47h) corresponding to each the valves.

The switch buttons are separated into "exghaust position"(a position to exhaust an air from a bag), "close position(a position to close an exclusive valve) and "open position"(a position to open the valve). The three way valve means that this valve has three paths such as an inlet path, an outlet path and an exhaust path in the air communication.

Now it is referred to the preferred example of the operation with respect to the above compositions. In the elevation mechanism of the seat portion, it is reverted that the elevation air bags(28) is disposed in the space(x) provided between the bottom of the seat body(A) and the bed(37) and also the mobility air bags(29a)(29b) are disposed in the space(y) provided to put the partition wall(21b) between both air bags(29a)(29b) and the air bags(29a) is used for forwarding the seat body(A) toward the front direction and the air bags(29b) is used for backing the seat(A) toward the rear direction.

In the general operation of the air bag system, a switch button is turned to "open position", then the compressor(43) sends a compressed air into an air bag through the air feeding tube(42)(46)(Fig.15J and the compressed air is filled within the air chamber(40'a) of the bags(40a) passing through the communicating vents(41) wherein the bags(40a) is inflated.

according to the expansion of the air bags(40a), each portion of the system is moved toward the direction which the air bags(40a) is expanded.

According to the above action principle of air bag system, for example, these doglegged lever plates such as the plate(1d) which is embedded in the lower half portion(a) of the seat back and another lever plate(b2) which is embedded in the upper half portion(1) of the seat back are pressed toward the rear direction by the expansions of these air bags(6)(11) and then the upper half portion(1) and the head-rest portion(b) are inclined toward the front direction separately according to the separated operation instructed from the control panel(47).

As to the seat gardient(13), it is lifted by the expansion of the air bags(16). In the thigh-support(15), the gradient of the thigh-support pad(15) is controlled by the air bags(16), each the side-supports(d) provided on the both sides of the seat portio-n(C) and the both sides of the seat back(a) is moved respectively toward the inside direction of the seat portion(C) and the seat back(a), in this way when these each portion reaches a preferable position, the switch buttons of the control panel(47) is turned to close position" and then stops the feeding of compressed air into each air bag.

In general, when a switch button is turned to open position", a corresponding valve opens its inlet and outlet paths to an air bag and closes its exhaust path to block the leakage of air from the valve. In contrast, when the switch button is turned to "close position", the valve closes all the paths of inlet, outlet and exhaust.

In the above state of each path position, now if the occupant wishes to incline the upper half portion(a) of the seat back or the head-rest pad(b) toward rear direction, and also wishes to move the side-support(d) outward, in Fig.14, it is operated that the switch button(45L) of the half portion(a) or (45k) of the head-rest(b) and the switch button(45h)(45j) are turned to " exhaust position", and then these valves close the inlet path and open the outlet and exhaust paths contrarily, so that all air contained in those air bags are exhausted to outside and the bags are contracted respectively.

In case of operating the elevation mechanism, the switch button (47g) is turned to "open position", firstly the valve(45e) of the lock device(30) opens the inlet and outlet paths and closes the exhaust path so that the air bag(33) of the locking device is inflated prior to the inflation of the main air bag(28) for lifting the seat body(A) because of the interceptive existence of a delay timer arranged between the locking device valve(45e) and the main bag valve(45d). Upon the completion of disengaging the locking device, the main air bag(28) is followed to expand by opening the inlet and outlet paths and also closing the exhaust path of the valve(45d).

When the elevation reaches a preferable position, the switch button(47g) is turned to "close position" and then the main bag valve(45d) close all the paths of the inlet, outlet and exhaust so that the air supply into the main bags(28) is stopped, on the other hand, the locking device valve(45e) closes the inlet path only and open the outlet and exhaust paths to exhaust the air contained within the locking device air bag(33) for engaging the locking portion with the vertical rack(30b') and lock pin(17). By engaging the locking device, the seat body(A) is secured at the preferable position.

In case of descending the seat body(A), when the switch button(47g) is turned to "exhaust position", it is specified that the main bag valve(45f) is instructed to open the inlet and outlet paths in a moment(about 2 seconds) to send the air into the main bags(28) to pressurized it from the control panel(47). this sudden pressurization is purposed to minimize the seat load including the occupant's body weight prior to the disengagement of the locking device to facilitate the disengagement smoothly without any excessive load. During the pressurization, the locking device valve(45e) is instructed to open readily the inlet and outlet paths and closes the exhaust path to inflate the bags(33). Upon the completion of disengagement of the locking device, the main bag valve(45d) is further instructed to close the inlet path only and open the outlet and exhaust paths as usual so that the descent of the seat body(A) is achieved. These operation sequences of each valve(45d)(45e) are originally programed in the circuit of the control panel.

In the mobility of the seat body(A), in forwarding, when the switch button(47h) is turned to "open position", the locking device valve(45c) is instructed to open the inlet and outlet paths and close the exhaust path to inflate the locking device bag(34) initially so that the locking device((31b)(27a) is disengaged. After that, due to a delay timer, the forwarding valve(29a) is instructed to open the inlet and outlet paths and close the exhaust path to expand the bags(29a) to forward the seat body(A) through the partition wall(21b). On the other hand, the backing valve(45a) is instructed to close the inlet path only and open the outlet and exhaust paths to contract the air bag(29b) according to the sequent instructions of the program.

When the seat body(A) reaches the preferable position, the switch button(47h) is turned to "open position", the forwarding valve(45b) is instructed to close the inlet and outlet paths and open the exhaust path. The locking device valve(45c) is instructed to open the inlet and outlet paths and close the exhaust path to inflate the locking device air bag(34) to disengage the locking device(31b)(27a), after that the backing valve(45a) is instructed to open the inlet and outlet paths and close the exhaust path to inflate the forwarding air bags(29b). According to the expansion of the bags(29b), contrary the forwarding air bags(29a) is contracted by exhausting the air from the exhaust path of the valve(45b).

In the modification of the structure of switch button having the three-way positions, however, it may be modified to another type swutch. The centralized control panel may be arranged on around the dashboard of vehicle.

In further modifications, the various side-ports(d) are described in the present invention, however, the side-ports may be omitted from the invention, and further any structure which is not referred to in the description may be changed to another different structure, therefore, in Claim 1 and Claim 2 of the present invention the structure of the seat portion shown in Fig.20 may be another well known type structure.

In Claim 3 to Claim 6, the seat back portion(a) may be another typed seat back, and further the existence of the head-rest portion in the present invention may be optional but not required in the present invention, and in Claim 4 and Claim 6 the thighsupport(15) may be not required in the present invention.

In Claim 3, it may be adaptable such the type of seat portion(C) without the elevation mechanism and mobility mechanism as shown in Fig.23 and Fig.24, and also in Claim 5, it may be adaptable such the type of seat portion(C) without the elevation mechanism as shown in Fig.28 and Fig.30.

As described in the above, this invention may be practiced or embodied in still other ways without departing from the spirit or essential character thereof. The preferred embodiments described herein are therefore illustrative and not restrictive, the scope of the invention being indicated by the appended claims and all variations which come within the meaning of the claims are intended to be embraced therein.

Claims

What is claimed is:

1. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a doglegged shape lever plate disposed vertically and pivotally with the upper end of a seat back at the bent corner portion of said lever plate; the upper half portion of said lever plate arranged to project upwardly from said the corner portion thereof, the lower half portion of said lever plate arranged to be housed within a box shaped cylinder; said box shaped cylinder having a rectangular cross section, which being embedded integrally in the thickness of said seat back to open the upper opening of said rectangular cylinder at said the upper end of said seat back;; said the lower half portion of said lever plate positioned to be free in the hollow space of said rectangular cylinder so as to swing the free end of said the lower half portion between both interior walls of said rectangular cylinder; a head-rest pad portion arranged on said the upper end of said seat back, which fixed with said the upper half portion of said lever plate projected by inserting said upper half portion into said head-rest pad body along with the rear wall of said pad body therein; a plurality of air bags jointed partially each other as stacked multiply so as to form a bellows, a plurality of air communicating vents provided at their portions jointed partially each other with an air feeding tube jointed with at least one edge of said air bags' periphery to feed a compressed air for expanding and contracting said bellows type air bags; and said the plurality of air bags disposed fixedly between said the interior wall of the front side of said rectangular cylinder and the opposed surface of said the upper half portion of said lever plate, wherein the angle of inclination of said head-rest pad portion can be controlled by said bellows type air bags according to the expansion and contraction thereof.

2. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a twice-folded type seat back consisting of a lower half seat back and an upper half seat back with a head-rest on the upper end thereof; said lower half seat back equipped with a inclinational angle controlling mechanism of said seat back in which consisting of a doglegged shaped lever plate, a rectangular cylinder embedded in said lower half seat back within the thickness thereof and a plurality of air bags stacked multiply to form a bellows;; said lever plate consisting of an upper half portion and a lower half portion of said lever plate opposedly from said doglegged corner which positioned to pivot at the upper end of said seat back, so that said upper half portion thereof arranged to project upwardly from said the upper end of said lower half portion of said seat back, said lower half portion of said lever plate positioned to be free in the hollow space of said rectangular cylinder so as to swing the free end of said lower half portion between both interior walls of said rectangular cylinder;; said upper half portion of said seat back jointed upright with said the upper end of said lower half portion of said seat back, which fixed with said the upper half portion of said lever plate projected by inserting said upper half portion of said lever plate into the body of said upper half portion of said seat back from the bottom thereof along with the rear wall of said the body of said upper half portion of said seat back therein; said the plurality of air bags jointed partially each other as stacked multiply to form a bellows, a plurality of air communicating vents provided at their portions jointed partially each other with an air feeding tube jointed at least one edge of said air bags' periphery to feed a compressed air therein for expanding and contracting said bellows type air bags;; said the plurality of air bags disposed fixedly between said the interior wall of the front side of said rectangular cylinder and the opposed surface of said the upper half portion of said lever plate, wherein said the inlinational angle of said the upper half portion of said seat back can be controlled according to the expansion and contraction of said bellows type air bags;; said the upper half portion of said seat back in which equipped with the same of said inclinational angle controlling mechanism as used to joint each other between said lower half portion and said upper half portion of said twice-folded type seat back, said controlling mechanism consisting of said lever plate, said rectangular cylinder and said the plurality of air bags in which being embedded integrally in said the upper portion of said seat back within the thickness thereof in the same manner of said controlling mechanism equipped with said the lower half portion of said seat back; and said head-rest pad portion jointed with said the upper end of said the upper half portion of said seat back, which fixed with said the upper half portion of said lever plate projected from said the upper end of said the upper half portion of said seat back by inserting said the upper half portion of said lever plate into said head-rest pad body along with the rear wall of said pad body therein, wherein said the inclinational angle of said head-rest pad portion also can be controlled by said air bags according to said the expansion and contraction thereof.

3. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a thigh-support pad with an air bags housed therein mounted on the outer end of a extrusive plate; said extrusive plate provided under the bottom of a seat portion horizontally to be moved reciprocatively in the front direction of said seat portion, said the outer end of said extrusive plate provided to dogleg downwardly with a length capable of mounting the bottom of said thigh-support pad, the other end of said extrusive plate provided to fix a vertical backplate for receiving the inflation of another air bags;; A plurality of air bags stacked multiply to form a bellow in which provided to dispose between said the bottom of said thigh-support and the opposed surface of said doglegged end of said exterusive plate, wherein said the plurality of air bags can control the gradient of said thigh-support pad according to the expansion and contraction thereof; and said another bellows type air bags provided to dispose between said vertical backplate of said extrusive plate and the opposed interior wall of the rear side of said seat portion, wherein said another air bags can control each the reciprocative movement of said extrusive plate according to the expansion and contraction thereof.

4. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a pair of X-shaped link motion provided between the bottom of a seat portion and the upper surface of a bed along with the both side edge lines of said seat portion, said link motions provided to move in vertical direction and to keep the seat level according to the elevation of said seat portion; a plurality of air bags jointed partially each other as stacked multiply so as to form a bellows, a plurality of air communicating vents provided at their portion jointed partially each other with an air feeding tube jointed with at least one edge of said air bags' periphery to feed a compressed air for expanding and contracting said bellows type air bags;; said the plurality of air bags disposed fixedly in the space provided under the bottom of said seat portion to put said the plurality of air bags between said the pair of X-shaped link motions, wherein said seat portion is risen and descended according to the expansion and contraction of said air bags;; a locking device provided to lock the elevating movement of said seat portion at a preferable level in combination with a rack and lock pin, said locking device consisting of a L-shaped frame, the corner of said L-shaped frame fixed pivotally with said the upper surface of said bed through a bracket, said Lshaped frame consisting of a vertical frame portion and a horizontal frame portion, said vertical frame portion provided with a rack gears to engage with a lock pin projected from the rear end of said seat bottom portion, said horizontal frame portion provided with a multiply stacked type air bags between the bottom surface of the free end of said horizontal frame portion and said the upper surface of said bed, wherein said horizontal frame portion will be moved up and down according to the expansion and contraction of said multiply stacked type air bags to disengage and engage said rack gears with said lock pin through the swing movement of said vertical frame portion.

5. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a pair of rails having a convex shape in which provided on the floor of fixing said vehicle seat body in parallel along the both side edge lines of said seat body, said convex shaped rails further provided with a rack gears hobbed along the outer of one of said convex shaped rails; a pair of concave shaped frames fixed with the bottom surface of said seat body so as to engage said concave shaped frame slidably with said convex shaped rails respectively; a partition wall provided to hang down from said the bottom surface of said seat body at a predetermined position thereof;; a pair of multiply stacked type air bags provided each other to put said partition wall between both air bags, wherein said seat body is forwarded through said partition wall when one unit of said air bags disposed in the rear side space from said partition are expanded by feeding a compressed air into said bags, in contrast said seat body is backed through said partition when the other unit of said air bags in the front side space are expanded; a locking device provided to lock the mobility of said seat body in combination with the lock pins of said locking device and said rack gears hobbed with said concave shaped rails, said locking device consisting of L-shaped lever plate having a lock pins at the lower end and a smaller sized air bags, said L-shaped lever plate disposed with said convex shaped frame at right angle through a pivotal bracket fixed with said frame; and said smaller sized air bags disposed between the vertical portion of said L-shaped lever plate and a backplate fixed projectedly with said frame, wherein said lock pins of said lever plate is disengaged and engaged with said rack gears according to the expansion and contraction of said smaller sized air bags.

6. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a pair of X-shaped link motion provided between the bottom of a seat portion and the upper surface of a bed along with the both side edge lines of said seat portion, said link motion provided to move in vertical direction and to keep the seat level according to the elevation of said seat portion; a plurality of air bags jointed partially each other as stacked multiply so as to form a bellows, a plurality of air communicating vents provided at their portion jointed partially each other with an air feeding tube jointed with at least one edge of said air bags' periphery to feed a compressed air for expanding and contracting said bellows type air bags;; said the plurality of air bags disposed fixedly in the space provided under the bottom of said seat portion to put said the plurality of air bags between said the pair of X-shaped link motions, wherein said seat portion is risen and descended according to the expansion and contraction of said air bags; a pair of rails having a convex shape in which provided on the floor of fixing said vehicle seat body in parallel along the both side edge lines of said seat body, said convex shaped rails provided with a rack gears hobbed along the outer side of one of said convex shaped rails; a pair of concave shaped frames fixed with the bottom surface of said seat body so as to engage said concave shaped frame slidably with said convex shaped rails respectively; a partition wall provided to hang down from said the bottom surface of said seat body at a predetermined position thereof;; a pair of multiply stacked type air bags provided each other to put said partition wall between both air bags, wherein said seat body is forwarded through said partition wall when one unit of said air bags disposed in the rear side space from said partition are expanded by feeding a compressed air into said bags, in contrast said seat body is backed through said partition when the other unit of said air bags in the front side space are expanded;; a locking device provided to lock the elevating movement of said seat portion at a preferable level in combination with a rack and lock pin, said locking device consisting of a L shaped frame, the corner of said L-shaped frame fixed pivotally with said the upper surface of said bed through a brackets, said L-shaped frame consisting of a vertical frame portion and a horizontal frame portion, said vertical frame portion provided with a rack gears to engage with a lock pin projected from the rear end of said seat bottom portion, said horizontal frame portion provided with a multiply stacked type air bags between the bottom surface of the free end of said horizontal frame portion and said the upper surface of said bed, wherein said horizontal frame portion will be moved up and down according to the expansion and contraction of said multiply stacked type air bags to disengage and engage said rack gears with said lock pin through the swing movement of said vertical frame portion.

a locking device provided to lock the mobility of said seat body in combination with the lock pins of said locking device and said rack gears hobbed with said concave shaped rails, said locking device consisting of L-shaped lever plate having a lock pins at the lower end and a smaller sized air bags, said L-shaped lever plate disposed with said convex shaped frame at right angle through a pivotal bracket fixed with said frame; and said smaller sized air bags disposed between the vertical portion of said L-shaped lever plate and a backplate fixed projectedly with said frame, wherein said lock pins of said lever plate is disengaged and engaged with said rack gears according to the expansion and contraction of said smaller sized air-bags.

7. A vehicle seat capable of adjusting each region driven by air bags as a substitute for a hydraulic cylinder, comprising: a twice-folded type seat back consisting of a lower half seat back and an upper half seat back with a head-rest on the upper end thereof, said lower half seat back equipped with a inclinational angle controlling mechanism of said seat back in which consisting of a doglegged shaped lever plate, a rectangular cylinder embedded in said lower half seat back within the thickness thereof and a plurality of air bags stacked multiply to form a bellow, said the upper half portion of said seat back jointed upright with said the upper end of said lower half portion of said seat back through the upper half portion of said doglegged shaped lever plate provided with said the upper end of said lower half portion of said seat back, said the upper half portion also equipped with another said inclinational angle controlling mechanism for controlling said head-rest portion in which being embedded in the upper end of said the upper half portion of said seat back, wherein both said the upper half portion of said seat back and said headrest portion are adjusted their inclination respectively according to the expansions and contractions of both air bag systems;; a thigh-support pad with an air bags housed therein mounted on the outer end of a extrusive plate, said extrusive plate provided under the bottom of a seat portion horizontally to be moved reciprocatively in the front direction of said seat portion by means of a multiply stacked type air bags disposed between a backplate fixed with the rear end of said extrusive plate, wherein said thigh-support pad cab be moved its gradient and position preferably according to the expansions and contractions of both air bags;; an elevation mechanism of said seat portion which consisting of a pair of X-shaped link motions with its locking device and a plurality of air bags stacked multiply capable of lifting up said seat portion together with the occupant according to the expansion of said air bags, said the pair of X-shaped link motions provided to keep the level of said seat portion between the bottom of said seat portion and a bed to support said link motions along with the both side edge lines of said seat portion, said locking device consisting of L-shaped lever frame with a rack gears on the vertical portion of said lever frame to disengage and engage with a lock pin which disposed projectedly from the rear end of the bottom base of said seat portion according to the expansion and contraction of another smaller sized air bags disposed under the horizontal portion of said lever frame, wherein said seat portion is elevated; and a mobilizing mechanism of said seat portion which consisting of a pair of concave shaped frames fixed under the bottom of said seat portion, a pair of convex shaped rails fixed on the floor of setting said seat portion to engage with said concave shaped frames to make the frames to move slidably on said rails, a partition wall provided to hang down from the bottom of said seat portion, a pair of multiply stacked type air bags provided to put said partition wall between the pair of said air bags capable of forwarding and backing said seat portion through said partition wall according to the expansion and contraction of said the pair of said air bags alternately and a locking device to lock the mobility of said seat portion at a preferable position in the longitudinal direction in combination with a rack gears hobbed with the outer side of one of said concave shaped rails and a lock pin provided at right angle with the side of one of said convex shaped frames corresponding to said rails with said rack gears, another smaller sized air bags provided between a locking lever with said lock pin and a backplate fixed with a bracket from said the one side of said frames to disengage and engage said locking combination according to the expansion and contraction of said smaller sized air bags.