Vehicle seat

A vehicle seat includes a seat cushion which has a frame structure and a cushion member combined with the frame structure, the frame structure including a pair of spaced apart side frame members, a front frame member fixed to forward end portions of the side frame members, a connecting shaft extending between rearward end portions of the side frame members and interconnecting the rearward end portions of the side frame members, a plurality of zigzag springs stretched between the front frame member and the connecting shaft, the cushion member being laid on the zigzag springs, and retainers mounted on the connecting shaft, the zigzag springs being engaged at one terminals thereof with the retainer.

FIELD OF INVENTION

The present invention relates to a vehicle seat and, more particularly, to a vehicle seat including a seat cushion which comprises a frame structure, a plurality of zigzag springs stretched in the frame structure, and a cushion member supported to the frame structure so as to be laid on the zigzag springs, and combined with the frame structure.

BACKGROUND OF THE INVENTION

As a conventional vehicle seat, there has been proposed a vehicle seat which includes a seat cushion, a seat track mechanism for allowing the vehicle seat to be moved forward and rearward in a vehicle, and a mechanism for causing the seat cushion to rise and fall in order to adjust a height of the vehicle seat. Japanese Patent Application Laid-Open No. 2002-142908 discloses the conventional vehicle seat. The seat cushion of the vehicle seat comprises a frame structure, a plurality of zigzag springs stretched in the frame structure, and a cushion member supported to the frame structure so as to be laid on the zigzag springs, and combined with the frame structure.

The frame structure is formed into a substantially quadrilateral ring-shape and comprises a pair of spaced apart side frame members, a first connecting shaft arranged between rear end portions of the spaced apart side frame members, and a front frame member fixed to forward end portions of the spaced apart side frame members. The zigzag springs are coupled at both terminals thereof to the front frame member and the first connecting shaft.

The seat track mechanism comprises a pair of parallel stationary rails spaced apart from each other and mounted on a floor of the vehicle through brackets, and a pair of parallel movable rails spaced apart from each other and slidably engaged with the stationary rails.

The mechanism for causing the seat cushion to rise and fall comprises linkage means provided between the movable rails and the side frame members of the frame structure. The linkage means comprises a pair of forward and rearward linkage bars connected at both ends thereof to each of the movable rails and each of the side frame members. More particularly, the forward linkage bar is pivotally supported at one end thereof through a first support pin to a portion of a corresponding movable rail which is adjacent a forward end portion of the corresponding movable rail, and supported at the other end thereof through a second support pin to a portion of a corresponding side frame member which is adjacent the front frame member. A second connecting shaft is arranged between forward linkage bars connected through second support pins to the side frame members, and coupled at both ends thereof to the second support pins. The rearward linkage bar is pivotally supported at one end thereof through a third support pin to a portion of a corresponding movable rail which is adjacent a rearward end portion of the corresponding movable rail, and supported at the other end thereof through a fourth support pin to a rear end portion of a corresponding side frame member of the frame structure. The first connecting shaft is arranged between rearward linkage bars connected through fourth support pins to the side frame members, and coupled at both ends thereof to the fourth support pins and the rearward end portions of the side frame members.

The forward and rearward linkage bars are adapted to be actuated by a driving motor or an operating knob so as to be pivoted. When the forward and rearward linkage bars are pivoted in a predetermined direction by the driving motor or the operating knob so as to operatively stand up, the vehicle seat is lifted up. When the forward and rearward linkage bars are pivoted in the opposite direction so as to be operatively inclined, the vehicle seat falls.

In a case where each of the zigzag springs is coupled at a rear terminal thereof directly to the first connecting shaft, when the first connecting shaft is moved as the linkage members are pivoted and the seat cushion rises, the rear terminal of the zigzag spring is wound around the first connecting shaft, whereby the zigzag spring may be twisted and irrecoverably deformed. Furthermore, it take a lot of labor to couple the rear terminals of the zigzag springs directly to the first connecting shaft by welding for example. In order to overcome the problems, the rear terminals of the zigzag springs of the conventional vehicle seat are coupled to the first connecting shaft through retainers.

Referring now toFIGS. 1 and 2, the conventional vehicle seat will be discussed in greater detail hereinafter in order to facilitate understanding of the present invention. In the conventional vehicle seat, a round pipe is employed as the first connecting shaft J of the frame structure. The zigzag springs S (only one zigzag spring S is shown inFIGS. 1 and 2) are coupled at forward terminals thereof directly to the front frame member F of the frame structure, and coupled at rearward terminals thereof to the first connecting shaft J by substantially S-shaped retainers R (only one retainer R is shown inFIGS. 1 and 2). Each of the retainers R comprises a first substantially C-shaped section r1and a second substantially C-shaped section r2continuing from the first C-shaped section r1. First substantially C-shaped sections r1of the retainers R are rotatably mounted on the first connecting shaft J. The rearward terminals of the zigzag springs S are hooked on second substantially C-shaped sections r2of the retainers R.

The rearward terminal of each of the zigzag springs S is merely hooked on a corresponding retainer R and supported to the retainer R at one point thereof, so that when a person P sits on the vehicle seat and a weight load of the person P is then applied to the seat cushion, the retainers R are rotated around the first connecting shaft J in a clockwise direction while being pulled downwardly at the second substantially C-shaped sections r2thereof as shown inFIG. 2. Therefore, when compared with zigzag springs coupled at rearward terminals thereof directly to the first connecting shaft, the zigzag springs coupled at the rearward terminals thereof to the first connecting shaft through the retainers are considerably flexed downwardly as the retainers R are rotate in the clockwise direction while being pulled downwardly. The downward flexing of the zigzag springs deteriorates a cushioning condition of the seat cushion.

Furthermore, the retainers R are each formed into a substantially S-shape, so that each time the weight load of the person is applied to the seat cushion, the retainers R are drawn downwardly by the weight load and gradually deformed. As a result, when the person sits on the vehicle seat several times, the retainers R are irrecoverably deformed.

SUMMARY OF THE INVENTION

The present invention has been made with a view to overcoming the foregoing problems of the prior art vehicle seat.

It is therefore an object of the present invention to provide a vehicle seat in which a cushioning condition of a seat cushion can be kept constant.

It is another object of the present invention to provide a vehicle seat in which a plurality of zigzag springs can be easily and positively coupled to a frame structure for a seat cushion through retainers which will not deteriorate a cushioning condition of the seat cushion.

In accordance with one aspect of the present invention, there is provided a vehicle seat1including a seat cushion which has a frame structure and a cushion member combined with the frame structure. The frame structure comprises a pair of spaced apart side frame members, the side frame members having forward and rearward end portions, a front frame member fixed to the forward end portions of the side frame members, a connecting shaft extending between the rearward end portions of the side frame members and interconnecting the rearward end portions of the side frame members, a plurality of zigzag springs stretched between the front frame member and the connecting shaft, the cushion member being laid on the zigzag springs, each of the zigzag springs having first and second terminals, the first terminal being coupled to the front frame member, the second terminal being formed into a substantially U-shape in outline and comprising first and second spaced apart axial portions and an intermediate axial portion interconnecting the first and second axial portions, and a plurality of retainers for coupling second terminals of the zigzag springs to the connecting shaft therethrough. Each of the retainers comprises a substantially U-shaped body in cross-section, a first spring-receiving section extending laterally from one end of the U-shaped body, and a second spring-receiving section extending laterally from the other end of the U-shaped body. The U-shaped body of the each of the retainers is mounted on the connecting shaft with an opening thereof facing downward. The each of the zigzag springs is coupled at the second terminal thereof to a corresponding one of the retainers with the first axial portion and the second axial portion being engaged with a first spring-receiving section of the corresponding retainer and a second spring-receiving section of the corresponding retainer, respectively, and with an intermediate axial portion thereof being located under the connecting shaft and contacted with the connecting shaft.

The U-shaped body of the each of the retainers may be mounted on the connecting shaft so as to be rotatable with respect to the connecting shaft.

The retainer may be formed by bending a metal plate. The first spring-receiving section of the retainer is located inside the frame structure and extends horizontally. The second spring-receiving section of the retainer is located outside the frame structure and is bent into a substantially U-shape in cross-section.

The second axial portion of the second terminal is provided with an engaging axial portion extending laterally from a free end of the second axial portion, the engaging axial portion being engaged with an edge of the second spring-receiving section.

The vehicle seat may include a mechanism for causing the seat cushion to rise and fall in order to adjust a height of the vehicle seat.

The mechanism comprises a pair of spaced apart base members mounted on a floor of a vehicle, linkage means provided between the side frame members and the base members, and actuating means for actuating the linkage means.

In accordance with another aspect of the present invention, there is provided a retainer for coupling a zigzag spring to a frame structure for a seat cushion of a vehicle seat. The frame structure comprises a pair of spaced apart side frame members, the side frame members having forward and rearward end portions, a front frame member fixed to the forward end portions of the side frame members, and a connecting shaft extending between the rearward end portions of the side frame members and interconnecting the rearward end portions of the side frame members. The zigzag spring has first and second terminals. The first terminal of the zigzag spring is coupled to the front frame member. The second terminal of the zigzag spring is formed into a substantially U-shape in outline and comprises first and second spaced apart axial portions and an intermediate axial portion interconnecting the first and second axial portions. The retainer comprises a substantially U-shaped body in cross-section, a first spring-receiving section extending laterally from one end of the U-shaped body, and a second spring-receiving section extending laterally from the other end of the U-shaped body. The U-shaped body of the retainer is mounted on the connecting shaft with an opening thereof facing downward. The zigzag spring is coupled at the second terminal thereof to the retainer with the first axial portion and the second axial portion being engaged with the first spring-receiving section of the retainer and the second spring-receiving section of the retainer, respectively, and with an intermediate axial portion thereof being located under the connecting shaft and contacted with the connecting shaft.

In accordance with still another aspect of the present invention, there is provide a connecting structure for coupling a zigzag spring to a frame structure for a seat cushion of a vehicle seat. The frame structure comprises a pair of spaced apart side frame members, the side frame members having forward and rearward end portions, a front frame member fixed to the forward end portions of the side frame members, and a connecting shaft extending between the rearward end portions of the side frame members and interconnecting the rearward end portions of the side frame members. The zigzag spring has first and second terminals. The first terminal is coupled to the front frame member. The second terminal is formed into a substantially U-shape in outline and comprising first and second spaced apart axial portions and an intermediate axial portion interconnecting the first and second axial portions. The connecting structure comprises a retainer. The retainer comprises a substantially U-shaped body in cross-section, a first spring-receiving section extending laterally from one end of the U-shaped body, and a second spring-receiving section extending laterally from the other end of the U-shaped body. The U-shaped body of the retainer is mounted on the connecting shaft with an opening thereof facing downward. The zigzag spring is coupled at the second terminal thereof to the retainer with the first axial portion and the second axial portion being engaged with the first spring-receiving section of the retainer and the second spring-receiving section of the retainer, respectively, and with an intermediate axial portion thereof being located under the connecting shaft and contacted with the connecting shaft.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 3 and 4, there is illustrated a frame structure for a seat cushion of a vehicle seat according to the present invention. The frame structure is formed into a substantially quadrilateral ring-shape. More particularly, the frame structure comprises a pair of side frame members1spaced apart from each other, a first connecting shaft3arranged between rear end portions of the side frame members and interconnecting the rear end portions of the side frame members1, and a pan frame member4fixed to forward end portions of the side frame members1. A plurality of spaced apart zigzag springs11are stretched between the first connecting shaft3and the pan frame member4.

Incidentally, though being not shown inFIGS. 3 and 4, a cushion member is to be supported on the frame structure so as to be laid on the zigzag springs11, and is to be combined with the frame structure. As the first connecting shaft3, there may be employed a round pipe.

In the illustrated example, the vehicle seat is adapted to be moved forward and rearward in a vehicle through a seat track mechanism. The seat tract mechanism comprises a pair of substantially parallel stationary rails9spaced apart from each other and mounted on a floor of the vehicle by brackets (not shown), and a pair of substantially parallel movable rails2engaged with the stationary rails9in slidable relationship with the stationary rails9. Each of the movable rails2is provided with a pair of standing brackets50,60which are spaced apart from each other and mounted to the movable rail2.

In the illustrated example, the vehicle seat includes a mechanism for causing the seat cushion to rise and fall in order to adjust a height of the vehicle seat. The mechanism for causing the seat cushion to rise and fall comprises two pairs of linkage bars5,6interconnecting the side frame members1and the movable rails2, and actuating means10for actuating the first and second linkage bars5,6. More particularly, each of the side frame members1and each of the movable rails2are coupled to each other by a pair of spaced apart linkage bars5,6. The first linkage bar5is pivotally supported at a first end portion thereof to the first standing bracket50of a corresponding movable rail2by a first support pin51. First linkage bars5which are coupled to first standing brackets50of the movable rails2and the side frame members1are coupled to each other by a second connecting shaft53. The second linkage bar6is pivotally supported at a first end portion thereof to the second standing bracket60of a corresponding movable rail2by a second support pin61. A second end portion of the first linkage bar5is connected to a corresponding side frame member1by a third support pin52. The second linkage bar6extends rather than the first linkage bar5and is bent into a substantially L-shape. The second linkage bar6is connected at a substantially middle portion thereof to a corresponding side frame member1by a fourth support pin62. Fourth support pins62penetrate the side frame members1from the outside, and project in the frame structure. Second linkage bars6are supported through washers63(only one washer63is shown inFIG. 4) to the fourth support pins62so as to allow inner end portions of the fourth support pins62to penetrate the second linkage bars6. Both end portions of the first round pipe3are fitted on the inner end portions of the fourth support pins62and connected to the side frame members1.

When the first linkage bars5and the second linkage bars6are pivoted around the first support pins51and the second support pins61, respectively, by the actuating means, the frame structure rises or falls according to a pivotal direction of the first and second linkage bars5,6.

As shown inFIG. 4, the actuating means10comprises an operating knob10aarranged outside the frame structure and having a rotating axis which penetrates a side of the pan frame member4and one of the side frame members2and projects in the frame structure, a pinion gear10bmounted on an inner end portion of the rotating axis of the operating knob10a,a sector gear10drotatably supported to the side frame member2by a fifth support pin10cand meshed with the pinion gear10b,and a rod10fextending between the sector gear10dand a corresponding second linkage bar6. The rod10fis supported at one end thereof to the sector gear10dthrough a sixth support pin10e,and connected at the other end thereof to a second end portion of the second linkage bar6by a seventh support pin10g.

As discussed above, the zigzag springs11are stretched between the first connecting shaft3and the pan frame member4. As shown inFIG. 3, spaced apart retainers12which correspond in number to the zigzag springs11are mounted on the first connecting shaft3so as to be rotatable with respect to the first connecting shaft3. The zigzag springs11are coupled at rearward terminals thereof to the retainers12and coupled at forward terminals thereof to substantially arch-shaped engaging pieces13which are provided at the pan frame member4and correspond in number to the zigzag springs11. The arch-shaped engaging pieces13are spaced apart from one another and disposed across the width of the pan frame member4. More particularly, the engaging pieces13are formed by cutting portions of the pan frame member4and then causing the portions of the pan frame member4to be risen up from a surface of the pan frame member4.

As shown inFIG. 3, a forward terminal of each of the zigzag springs11is formed into a substantially U-shape in outline and has an engaging portion110which is formed by causing a free end region of the U-shaped terminal to be bent perpendicularly to the U-shaped terminal. The forward terminal of each of the zigzag springs11is inserted through a space between a corresponding arch-shaped piece13and the surface of the pan frame member4with a central portion thereof being laid on the surface of the pan frame member4, and with the engaging portion110being engaged with an edge of the arch-shaped piece13.

Referring toFIGS. 5 and 6, there is illustrated one of the retainers12and one of the zigzag springs11. The retainer12comprises a body12aof a substantially U-shape in cross-section mounted on the first connecting shaft3so as to be rotatable with respect to the first connecting shaft3, and first and second spring-receiving sections12b,12cprovided at both ends of the U-shaped body12a.The first spring-receiving section12bhorizontally extends laterally from one end of the U-shaped body12a.The second spring-receiving section12cis formed into a substantially U-shape in cross-section and extends upwardly from the other end of the U-shaped body12bwith an opening thereof facing upwardly. In the illustrated example, the retainer12is formed by bending a metal plate. The retainer12is mounted on the first connecting shaft3with an opening of the U-shaped body12afacing donwardly, with the first spring-receiving section12bthereof being located inside the structure frame and with the second spring-receiving section12cbeing located outside the frame structure.

The rearward terminal of each of the zigzag springs11is formed into a substantially U-shape in outline. More particularly, the rearward terminal of the zigzag spring11comprises a pair of spaced apart axial portions11a,11band an intermediate axial portion11cinterconnecting the spaced apart axial portions11a,11b.The rearward terminal of the zigzag spring11is coupled to a corresponding retainer12with the first axial portion11athereof being engaged with the first spring-receiving section12bof the retainer12, with the second axial portion11bthereof being received in and engaged with the second spring-receiving section12c,and with the intermediate axial portion11cthereof being located under the first connecting shaft3. The intermediate axial portion11cof the zigzag spring11is point-contacted with the first connecting shaft3. Thus, the retainer12can be maintained in a posture in which the opening of the substantially U-shaped body12afaces downward. In addition, the rearward terminal of the zigzag spring11can be easily and stably coupled to the first connecting shaft3through the corresponding retainer12.

As shown inFIG. 6, the rearward terminal of the zigzag spring11further has an engaging axial portion11dextending laterally from an end of the second axial portion11bthereof. The engaging axial portion11dof the zigzag spring11is engaged with an edge of the second spring-receiving section12cof the corresponding retainer12. Thus, the rearward terminal of the zigzag spring11can be securely coupled to the retainer12.

Again referring toFIG. 4, and referring toFIGS. 7 to 9, the operation of the mechanism for causing the seat cushion to rise and fall will be discussed hereinafter. In a condition where the frame structure is located at a lower position as shown inFIG. 4, the first and second linkage bars5,6are inclined rearward. In the condition ofFIG. 4, when the rotating axis of the operating knob10ais rotated in a clockwise direction, the pinion gear10bis rotated in the same direction. As the pinion gear10bis rotated in the direction, the sector gear10dmeshed with the pinion gear10bis rotated in the opposite direction or in a counterclockwise direction, whereby the rod10fis pulled forward. The forward pulling of the rod10fcauses the second linkage bars6to rotate around the support pins61so as to stand up, and then causes the first linkage bars5to rotate around the support pin51so as to stand up. Thus, the vehicle seat is lifted up as shown inFIG. 7.

The retainers12are rotatably mounted on the first connecting shaft3and engaged with the rearward terminals of the zigzag springs11as discussed above, so that even if the first connecting shaft3which interconnects the side frame members1is moved as the frame structure is lifted up, each of the retainers12on the first connecting shaft3is kept in the mounted condition in which the opening of the retainer12faces downward as shown inFIG. 8. Thus, an effective length of each of the zigzag springs11in the vehicle seat according to the present invention is kept constant because the rearward terminal of the zigzag spring11is not wound around the first connecting shaft11differently to the rearward terminal of a zigzag spring which is coupled directly to the first connecting shaft.

Furthermore, when the person P sits on the vehicle seat and the weight load of the person P is then applied to the seat cushion to thereby cause the zigzag springs11to be flexed downward as shown inFIG. 9(only one zigzag spring11is shown inFIG. 9), whereby the retainers12are pulled downward, the retainers12are not rotated and are maintained in the mounted conditions. More particularly, the retainers12are coupled to the zigzag springs11with the first spring-receiving portions12bthereof being engaged with the first axial portions11aof the zigzag springs11, with the second spring-receiving portions12cthereof being engaged with the second axial portions11bof the zigzag springs11. In addition, the intermediate axial portions11cof the zigzag springs11are point-contacted with the first connecting shaft3as discussed above. Thus, the U-shaped bodies12aof the retainers12are interposed between the first and second axial portions11a,11bof the zigzag springs11, and the first connecting shaft3is interposed between the U-shaped bodies12aof the retainers12and the intermediate axial portions11cof the zigzag springs11. Therefore, when the zigzag springs11are flexed downward as shown inFIG. 9, the first and second axial portions11a,11bof the zigzag springs11which are engaged with the first and second spring-receiving sections12b,12cof the retainers12are pulled downward whereby the retainers12are tightly fastened to the first connecting shaft3. At this time, any torque to tend to rotate the retainers12with respect to the first connecting shaft3is not generated, so that the retainers12are not rotated with respect to the first connecting shaft3and maintained in the mounted conditions. Therefore, a downward flexing mount of each of the zigzag springs11is restricted, so that a cushioning condition of the seat cushion can be kept constant. In addition, an effective length of each of the zigzag springs11can be maintained constant differently to each of the zigzag springs of the conventional vehicle seat. Furthermore, differently to the retainers of the conventional vehicle seat, there is no possibility that the retainers12of the present invention will be deformed as the zigzag springs11are flexed downward. Therefore, according to the present invention, it is possible to provide a vehicle seat in which a cushioning condition of a seat cushion can be kept constant. Incidentally, a reference numeral20inFIG. 9denotes the cushion member which is supported to the frame structure so as to be laid on the zigzag springs11and combined with the frame structure.

While the above description is made of the frame structure in which the round pipe-shaped connecting shaft is employed as a component constituting a rear section of the frame structure, this invention may be applied to a frame structure which comprises a U-shaped pipe member and a front frame member fixed to free ends of the U-shaped pipe member. The present invention may be also applied to a frame structure which a round pipe-shaped connecting shaft is employed in lieu of the pan frame member.

Furthermore, while the above description is made of the vehicle seat which includes the seat track mechanism and the mechanism for causing the seat cushion to rise and fall, the present invention may be applied to a vehicle seat which is not provided with such mechanisms. In a case where the present invention is applied to a vehicle seat which is provided with the mechanism for causing the seat cushion to rise and fall, but is not provided with the seat track mechanism, a pair of spaced apart base members which are mounted on a vehicle floor are employed in lieu of the stationary rails and the linkage means are provided between the side frame members and the base frame members.