Vehicle seat

The disclosure of Japanese Patent Application No. 2010-086789 filed on Apr. 5, 2010 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

1. Field of the Invention

The invention relates to a vehicle seat. More particularly, the invention relates to a vehicle seat in which a seat main body that is slidably provided on the floor of the vehicle can be placed in a tipped up position, in which a seat cushion is flipped up, and that is locked so as not to slide when the seat main body is in a position in which it has been slid from a predetermined range (i.e., a range within which the seat main body can be fixed when an occupant sits in the seat, i.e., the range in which the seat can be used); hereinafter referred to as the “usable range”) to an unusable range that is outside of the predetermined range.

2. Description of the Related Art

Japanese Patent Application Publication No. 2005-22551 (JP-A-2005-22551), for example, describes a vehicle seat structure in which the amount of room behind the seat is increased by flipping up a seat cushion toward the rear and sliding a seat main body forward (in the longitudinal direction of the vehicle) out of a seat-usable range and into an unusable range. This vehicle seat has two types of locking devices for locking the seat main body so that it will not slide. One locking device is a device that locks the seat main body in the seat-usable range only when the seat main body is in a position that allows an occupant to be seated. The other locking device is a device that locks the seat main body in the unusable range only when the seat cushion is in a tipped up position. Providing these two types of locking devices in this way makes it possible to ensure that the seat main body is always used (to sit on) in a safe range, and prevents the seat main body from being used (to sit on) in the unusable range that is outside of the seat-usable range.

However, this technology requires the two types of locking devices, which makes the structure complicated.

The invention makes it possible to lock a seat main body so that it will not slide in a seat-usable range, and lock the seat main body so that it will not slide in an unusable range, using one type of locking device.

A first aspect of the invention relates to a vehicle seat that is slidably provided on a vehicle floor, that includes a fixed rail that is fixed onto the vehicle floor; a slide rail that is slidably assembled to the fixed rail, a seat main body being provided on an upper portion of the slide rail; a locking device that is provided on the slide rail and that locks the slide rail such that the slide rail will not slide, by engaging with the fixed rail; and a switching mechanism that switches the locking device between a locked state and an unlocked state. The vehicle seat is configured such that the seat main body that is slidably provided on the vehicle floor is able to be locked so as not to slide when the seat main body is in a sittable position as well as when the seat main body is in a tipped up position in which a seat cushion is flipped up, in a preset seat-usable range, and the seat main body is able to be locked so as not to slide by being placed in the tipped up position, in a position in which the seat main body has been slid out of the seat-usable range and into an unusable range. The switching mechanism has a sliding member that is provided on the slide rail and that slides along a wall surface of the fixed rail, a step portion that is formed on the wall surface of the fixed rail and onto which the sliding member rides when the seat main body enters the unusable range, an unlocking mechanism that is provided on the seat main body and that unlocks the locking device and keeps the locking device unlocked in response to movement of the sliding member as the sliding member rides onto the step portion, and an unlocking operation canceling mechanism that is provided on the seat main body and that cancels an operation by the unlocking mechanism to unlock the locking device when the seat cushion is flipped up into the tipped up position.

According to this aspect, the locking device that locks the seat main body in place in the seat-usable range can be kept unlocked by moving the seat main body into the unusable range, such that the sliding member rides onto the step of the fixed rail, which causes the unlocking mechanism to operate. Accordingly, the seat main body can be prevented from being used to sit on in the unusable range. On the other hand, the seat main body can be locked in place even in the unusable range by switching the seat cushion to the tipped up position, such that the unlocking operation canceling mechanism cancels an operation by the unlocking mechanism to unlock the locking device. In this way, the seat main body can be locked in place in the seat-usable range, as well as locked in place in the unusable range by being placed in the tipped up position, using one type of locking device.

In the aspect described above, the unlocking mechanism may include a link that is connected to the locking device, and a first elongated hole that extends in a longitudinal direction of the link may be provided in the link. The unlocking operation canceling mechanism may include a link that is connected to the locking device, and a second elongated hole that extends in a longitudinal direction of the link may be provided in the link. The link of the unlocking mechanism and the link of the unlocking operation canceling mechanism may be connected together by a slide pin that slides in the first elongated hole and the second elongated hole. The unlocking mechanism keeps the locking device unlocked by having the link of the unlocking mechanism rotate in response to the movement of the sliding member, such that the slide pin pushes on the locking device. The unlocking operation canceling mechanism stops the slide pin from pushing on the locking device by having the link of the unlocking operation canceling mechanism rotate such that the slide pin slides along the elongated hole in the link of the unlocking mechanism when the seat cushion is in the tipped up position.

According to this structure, the mechanism by which operation by the unlocking mechanism to unlock the locking device is canceled by the unlocking operation canceling mechanism is embodied by a simple structure in which links with elongated holes in them are connected by a slide pin. By employing a mechanism that slides the slide pin in the elongated holes in this way, the slide pin is able to slide while being engaged with the links, following the movements of the links. Thus, the operation by the unlocking mechanism to unlock the locking device and the operation by the unlocking operation canceling mechanism to cancel this unlocking operation by the unlocking mechanism are able to be stably performed.

In the aspect described above, the unlocking mechanism may include an operating arm that is operated by the sliding member and extends out from the seat main body. The operating arm is arranged facing an upper surface of the sliding member, and the upper surface of the sliding member is provided exposed above the slide rail.

According to this structure, providing the upper surface of the sliding member exposed above the slide rail enables the operating arm to be easily assembled protruding from the seat main body and facing the upper surface of the sliding mechanism provided inside the slide rail.

The features, advantages, and technical and industrial significance of this invention will be described in the following detailed description of example embodiments of the invention with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a side view schematically showing the structure of a vehicle seat according to an example embodiment of the invention;

FIG. 2 is an enlarged perspective view of the main structure of the vehicle seat;

FIG. 3 is a side view of a seat main body that is locked so that it will not slide, in a seat-usable range;

FIG. 4 is a side view of a release lever that has been pulled up from the state shown in FIG. 3 ;

FIG. 5 is a side view of the seat main body after it has been slid to an unusable range from the state shown in FIG. 4 ;

FIG. 6 is a side view of a seat cushion that has been tipped up from the state shown in FIG. 5 ;

FIG. 7 is a side view of the release lever after it has been pulled up from the state shown in FIG. 6 ;

FIG. 8 is a side view of the seat main body that has been slid to the seat-usable range from the state shown in FIG. 7 ;

FIG. 9 is a side view of the release lever after it has been returned from the state shown in FIG. 8 ; and

FIG. 10 is a side view showing the seat cushion in the middle of being lowered from the state shown in FIG. 6 to its original position after having been in a tipped up position.

First, the structure of a vehicle seat according to an example embodiment will be described with reference to FIGS. 1 to 10 . The vehicle seat in this example embodiment is configured such that a seat main body 1 that forms the main body of a seating portion is provided fixed to an upper portion of a pair of left and right slider devices 6 that are arranged on a vehicle floor F, as shown in FIG. 1 . Here, the seat main body 1 includes a seat back 2 , a seat cushion 3 , and a headrest 4 . The seat back 2 and the seat cushion 3 are each provided connected to a base plate 5 that is fixed to the upper portion of the slider devices 6 .

More specifically, the seat back 2 is structured such that lower end portions on both sides of a back frame, not shown; that forms the skeleton of the seat back 2 are connected to the base plates 5 on both sides via a reclining device 8 . By the reclining device 8 , the back angle of the seat back 2 with respect to the base plates 5 is always fixed. This back angle can be adjusted by operating a walk-in lever, also not shown, that is provided on the seat main body 1 and unlocks the back angle via a cable, not shown.

Also, as shown in. FIGS. 2 and 3 , the seat cushion 3 is structured such that rear end portions on both sides of a cushion frame 3 F that forms the skeleton of the seat cushion 3 are rotatably connected (so as to be able to be raised and lowered) to a fixing plate 5 B that is integrally fixed to the base plate 5 on each side by a connecting shaft 3 A. More specifically, the seat cushion 3 is able to be rotated (both raised and lowered) with respect to the base plate 5 within a range within which an engaging plate 3 F 1 that is integrally formed with a rear upper portion of the cushion frame 3 F is able to move between a first engaging surface 5 C 1 formed on the fixing plate 5 B and a second engaging surface 5 C 2 formed on the fixing plate 5 B.

The seat cushion 3 is constantly urged in a direction in which it will flip up about the connecting shaft 3 A toward the rear of the seat by the urging force of a spring member, not shown, that is arranged between the cushion frame 3 F and the base plate 5 . However, when the seat cushion 3 is in a state in which it can be used to sit on, it is kept in a down position, in which it is laid down to the front to enable an occupant to sit on it, by fitting (engaging) an engaging pin 3 B 2 provided on the tip of an engaging arm 3 B that is connected to the cushion frame 3 F into (with) a first groove 5 B 1 formed in the fixing plate 5 B.

The engaging arm 3 B is rotatably connected to the cushion frame 3 F by a connecting shaft 3 B 1 . The engaging arm 3 B is constantly kept in the position in which the engaging pin 3 B 2 is fit into the first groove 5 B 1 , with the engaging arm 3 B being rotatably urged counterclockwise in the drawing by the urging force of the spring member, not shown. Incidentally, hereinafter, the terms “clockwise” and “counterclockwise” refer to directions with respect to the drawings. When the walk-in lever, not shown, is operated, the engaging arm 3 B rotates clockwise against the urging force of the spring member via the cable, not shown, such that the engaging pin 3 B 2 comes out of the first groove 5 B 1 , and as a result, the seat cushion 3 flips up toward the back of the seat while pivoting about the connecting shaft 3 A (see FIG. 6 ).

When the seat cushion 3 flips up, the engaging arm 3 B hangs down from the seat cushion 3 and is pulled upward with respect to the seat. In this pulled up position, the engaging pin 3 B 2 fits into a second groove 5 B 2 formed in the fixing plate 5 B, and becomes engaged, such that the seat cushion 3 is engaged in the flipped-up position (i.e., a tipped-up position). Also, as shown in FIG. 1 , operating the walk-in lever, not shown, also unlocks the back angle of the seat back 2 , such that the seat back 2 tilts forward and becomes engaged in this position.

Accordingly, the seat main body 1 is in a forward-tilted position (i.e., a walk-in position) with the seat back 2 and the seat cushion 3 folded up together facing one another. That is, the seat main body 1 is folded up compactly in the longitudinal direction of the vehicle. Also, as shown in FIGS. 2 and 3 , when the walk-in lever is operated, a cable 18 A that is connected to this walk-in lever pulls on a fourth operating link 18 . As a result, a release member 15 that is integrally provided with the fourth operating link 18 rotates clockwise, thus unlocking a locking device 6 C of the slider devices 6 that will be described later such that the seat main body 1 is able to slide. Incidentally, hereinafter, the term “lock” refers to fixing an object in a position so that it will not slide, and the term “unlock” refers to unfixing an object from a position in which it had been fixed so that it is able to slide.

As a result, the seat main body 1 becomes unlocked with respect to the vehicle floor F, so the seat main body 1 can be slid into the unusable range that is forward in the vehicle, thereby providing more room behind the seat, as shown in FIG. 1 . Incidentally, the locking device 6 C of the slider devices 6 can also be unlocked by pulling up on a release lever 11 provided on a side portion of the seat main body 1 . The structure of this specific operation will be described in more detail later.

Incidentally, a sliding range within which the vehicle seat can be slid in the longitudinal direction of the vehicle by the slider devices 6 includes a seat-usable range within which the seat main body 1 can be used to sit on, and an unusable range within which the seat main body 1 cannot be used to sit on. The seat-usable range is a range within which belt webbing of a seatbelt apparatus, not shown, provided on a side wall of the vehicle is able to be wrapped around the body of a seated occupant and effectively restrain the occupant. The unusable range is a range in front of the seat-usable range (in the longitudinal direction of the vehicle), and is set as a range within which the seat main body 1 is unable to be used to sit on because the belt tubing of the seatbelt apparatus, not shown, is unable to reach.

When the vehicle seat is positioned in the seat-usable range, the locking device 6 C (see FIGS. 2 and 3 ) is always locked so that it will not slide. The locking device 6 C can be unlocked by pulling up on the release lever 11 described above. Unlocking the locking device 6 C enables the seat main body 1 to be slid forward in the longitudinal direction of the vehicle and thus be moved into the unusable range.

When the vehicle seat is positioned in the seat-usable range, it can be locked in place by releasing (i.e., lowering) the release lever 11 , such that the locking device 6 C becomes locked again (i.e., is urged into the locked state again). However, as shown in FIG. 5 , if the release lever 11 is operated (i.e., pulled up) and the seat main body 1 is slid into the unusable range while in a sittable position (i.e., a position that allows it to be sat on), the locking device 6 C is prevented from locking, even if the release lever 11 is released.

As a result, the seat main body 1 is prevented from being sat on in the unusable range. However, when the vehicle seat is in the unusable range, the seat main body 1 can be locked in place by switching the locking device 6 C to a locked state, which is accomplished by operating the walk-in lever and tipping up the seat cushion 3 .

Hereinafter, the structure of a switching mechanism 7 that switches the state of the locking device 6 C of the slider devices 6 between a locked state and an unlocked state will be described. First, the structure of the slider devices 6 will be described. As shown in FIG. 2 , each slider device 6 includes a fixed rail 6 A that is integrally fixed to the vehicle floor F, a slide rail 6 B that is slidably assembled to the fixed rail 6 A in the longitudinal direction of the seat (i.e., the longitudinal direction of the vehicle), and the locking device 6 C that can lock the slide rail 6 B in place with respect to the fixed rail 6 A.

The fixed rail 6 A is formed by a single long steel sheet that is bent in the shorter direction in places. This fixed rail 6 A has a bottom surface portion 6 A 1 that faces up with respect to the seat, side portions 6 A 2 that stand upright with respect to the seat from edge portions on both the left and right sides of the bottom surface portion 6 A 1 , and bent back portions 6 A 3 that are bent back downward toward each other from upper edge portions of both of the side portions 6 A 2 . Meanwhile, the slide rail 6 B is also formed of a single steel sheet that is bent in the shorter direction in places. The slide rail 6 B has an upper portion 6 B 1 that faces up with respect to the seat, side portions 6 B 2 that extend downward with respect to the seat from edge portions on both the left and right sides of the upper portion 6 B 1 , and fin portions 6 B 3 that are bent back so as to rise up and away from each other on the lower edge portions of both of the side portions 6 B 2 .

The slide rail 6 B is slidably assembled to the fixed rail 6 A in the longitudinal direction by longitudinally inserting both fin portions 6 B 3 of the slide rail 6 B into the spaces formed by the bent back portions 6 A 3 of the fixed rail 6 A being bent back, from an open end portion at either the front or the back of the fixed rail 6 A, such that the upper portion 6 B 1 of the slide rail 6 B is exposed protruding up with respect to the seat from the gap between the bent back portions 6 A 3 of the fixed rail 6 A. Thus, the slide rail 6 B is kept from detaching from the fixed rail 6 A in the upward direction due to the fin portions 6 B 3 catching on the bent back portions 6 A 3 of the fixed rail 6 A.

The locking device 6 C is rotatably connected to the slide rail 6 B by a shaft pin, not shown, the axis of which extends in the longitudinal direction of the slide rail 6 B. This locking device 6 C has three lock pawls 6 C 1 on the tip, and is constantly urged in a direction in which these lock pawls 6 C 1 engage with lock holes 6 A 4 (in the seat-usable range; see FIG. 3 ) or lock holes 6 A 5 (in the unusable range; see FIG. 5 ) that are formed through the bent back portions 6 A 3 of the fixed rail 6 A, by the urging force of a spring member, not shown.

Thus, the slide rail 6 B is locked to the fixed rail 6 A by the slide rail 6 B being placed in a position where the lock pawls 6 C 1 line up with the lock holes 6 A 4 (see FIG. 3 ) or the lock holes 6 A 5 (see FIG. 5 ) such that the lock pawls 6 C 1 are urged to engage with the lock holes 6 A 4 or the lock holes 6 A 5 .

As shown in FIG. 2 , the locking device 6 C is able to be unlocked by a push plate portion 6 C 2 of the locking device 6 C being pushed downward by a release member 15 of an unlocking mechanism 10 , such that the locking device 6 C is pushed around in a direction against the urging force, and the lock pawls 6 C 1 come out of (i.e., disengage from) the lock holes 6 A 4 or the lock holes 6 A 5 .

Next, the structure of the switching mechanism 7 that switches the state of the locking device 6 C between a locked state and an unlocked state will be described. As shown in FIGS. 2 and 3 , the switching mechanism 7 includes a sliding member 20 , a raised step portion 6 A 6 , the unlocking mechanism 10 , and an unlocking operation canceling mechanism 30 . The sliding member 20 is provided on the slide rail 6 B and slides along the upper surface of the bottom surface portion 6 A 1 of the fixed rail 6 A. The raised step portion 6 A 6 is formed on the bottom surface portion 6 A 1 of the fixed rail 6 A. The sliding member 20 rides up on this raised step portion 6 A 6 when the seat main body 1 comes into a position in the unusable range. The unlocking mechanism 10 is provided on the seat main body 1 and unlocks the locking device 6 C using the movement of the sliding member 20 as it rides up on the raised step portion 6 A 6 . The unlocking operation canceling mechanism 30 is provided on the seat main body 1 and cancels the unlocking operation by the unlocking mechanism 10 on the locking device 6 C when the seat cushion 3 is in the tipped up position. Here, the raised step portion 6 A 6 serves as the step portion of the invention.

As shown in FIGS. 2 and 3 , the sliding member 20 is rotatably connected to the slide rail 6 B by a connecting shaft 21 . A horn-shaped sliding protrusion 22 that protrudes downward is constantly kept pressed against the upper surface of the bottom surface portion 6 A 1 of the fixed rail 6 A by gravity. This sliding member 20 is configured such that when the seat main body 1 enters the unusable range, the sliding protrusion 22 rides up on the raised step portion 6 A 6 formed on the bottom surface portion 6 A 1 of the fixed rail 6 A, which causes the sliding protrusion 22 to rotate counterclockwise about the connecting shaft 21 , as shown in FIG. 5 .

As shown in FIGS. 2 and 3 , the unlocking mechanism 10 includes the release lever 11 , a first operating link 12 , a second operating link 13 , a connecting shaft 14 , the release member 15 , a third operating link 16 , a slide pin 17 , and the fourth operating link 18 . Here, the third operating link 16 serves as a link that forms the unlocking mechanism of the invention. The release lever 11 is rotatably connected to the base plate 5 by a connecting shaft 11 A and rotates relative to the base plate 5 . The release lever 11 pivots within a range within which an engaging plate 11 B formed bent at a rear edge portion of the release lever 11 moves between an upper engaging surface 5 A 1 formed on the base plate 5 and a lower engaging surface 5 A 2 formed on the based plate 5 .

The release lever 11 is constantly urged to rotate counterclockwise by the urging force of a tension spring 11 C strung between the release lever 11 and the base plate 5 , and is kept engaged in a state (i.e., an initial position) in which it has been pulled down to a position in which the engaging plate 11 B abuts against the upper engaging surface 5 A 1 . The first operating link 12 is a long link, with the upper end portion in the drawing rotatably connected by a connecting pin 12 A to an end portion of the release lever 11 that extends farther toward the rear than the connecting shaft 11 A, and the lower end portion in the drawing rotatably connected to the second operating link 13 by a connecting pin 12 B.

The second operating link 13 is rotatably connected to the base plate 5 by the connecting shaft 14 . More specifically, as shown in FIG. 2 , the second operating link 13 is integrally fixed to the connecting shaft 14 , and the connecting shaft 14 is rotatably connected to the base plate 5 . Furthermore, the two release members 15 that unlock the locking device 6 C of the slider devices 6 are integrally fixed to the connecting shaft 14 .

Moreover, the fourth operating link 18 that rotates when pulled by the cable 18 A when the walk-in lever, not shown, is operated is also integrally fixed to the connecting shaft 14 . That is, the release members 15 , the second operating link 13 , and the fourth operating link 18 are integrally connected to the connecting shaft 14 , such that these all rotate as a single unit.

Initially, before the release lever 11 is pulled up, the release lever 11 is prevented from rotating counterclockwise in the initial position. The release members 15 , the second operating link 13 , and the fourth operating link 18 are connected to the release lever 11 via the first operating link 12 , and are also prevented from rotating counterclockwise in the initial positions shown in FIG. 3 . Here, the tension spring 15 A that urges the release members 15 to rotate counterclockwise about the connecting shaft 14 shown in FIG. 3 is strung between each of the release members 15 and the base plate 5 .

Therefore, the urging force that is applied to the release members 15 to urge them to rotate counterclockwise is further increased in a manner that also assists the urging force of the tension spring 11 C that is applied to the release lever 11 . Next, the third operating link 16 is rotatably connected to the base plate 5 by a connecting shaft 16 A, as shown in FIGS. 2 and 3 . More specifically, the third operating link 16 is integrally fixed to the connecting shaft 16 A, and the third operating link 16 A is rotatably connected to the base plate 5 .

Furthermore, an operating arm 16 B that extends downward to a position opposite an upper plate portion 23 of the sliding member 20 provided on the slide rail 6 B of the slider devices 6 described above is provided integrally fixed to the connecting shaft 16 A. That is, the third operating link 16 and the operating arm 16 B are both integrally connected to the connecting shaft 16 A, such that these all rotate as a single unit. The third operating link 16 and the operating arm 16 B are constantly urged to rotate clockwise about the connecting shaft 16 A shown in FIG. 3 by the urging force of a tension spring 16 C that is strung between the operating arm 16 B and the base plate 5 , and thus are kept in a state in which the upper plate portion 23 of the sliding member 20 is pushed downward by the tip end portion of the operating arm 16 B, such that the sliding protrusion 22 of the sliding member 20 is pushed onto the bottom surface portion 6 A 1 of the fixed rail 6 A.

Here, as shown in FIG. 2 , the sliding member 20 is set in a space where a portion of the slide rail 6 B has been cut out. The upper plate portion 23 of the sliding member 20 is pulled out toward the inside in the seat width direction from the slide rail 6 B such that the surface is exposed on the upper side with respect to the seat. As a result, the operating arm 16 B is able to face and engage with the upper plate portion 23 of the sliding member 20 without going inside the slide rail 6 B.

Incidentally, an elongated hole 16 D that extends straight in the longitudinal direction of the third operating link 16 is formed in a link portion of the third operating link 16 that extends to the left in the drawing. A slide pin 17 that can slide along the shape of the elongated hole 16 D is interlocked with the elongated hole 16 D. The slide pin 17 is also fit into an elongated hole 33 C formed in a seventh operating link 33 , that will be described later. When the seat cushion 3 is in a down position, in which it is laid down forward such that it can be sat on, the slide pin 17 is kept in a position near the left edge portion in the drawing inside the elongated hole 16 D of the third operating link 16 by the rotated position of the seventh operating link 33 .

With the unlocking mechanism 10 in the structure described above, when the release lever 11 is pulled up while seat main body 1 is positioned within the seat-usable range shown in FIG. 3 , the second operating link 13 is rotated clockwise via the first operating link 12 , as shown in FIG. 4 , such that the release member 15 that is integrated with this second operating link 13 rotates in the same direction. As a result, the push plate portion 6 C 2 of the locking device 6 C of the slider devices 6 is pushed downward, such that the locking device 6 C becomes unlocked.

As a result, the seat main body 1 becomes unlocked and thus can be slid in the longitudinal direction of the vehicle along the fixed rail 6 A. When the seat main body 1 is in the seat-usable range, i.e., when the sliding member 20 is in a range within which it slides on the bottom surface portion 6 A 1 of the fixed rail 6 A, the seat main body 1 can be locked again by releasing (i.e., lowering) the release lever 11 .

However, as shown in FIG. 5 , when the seat main body 1 is slid from the seat-usable range to the unusable range, i.e., when the seat main body 1 is slid to a position where the sliding member 20 rides up on the raised, step portion 6 A 6 of the fixed rail 6 A, the operating arm 16 B is pushed up by the upper plate portion 23 of the sliding member 20 that has ridden up on the step, and as a result, the third operating link 16 is pushed around counterclockwise. Accordingly, the slide pin 17 that is engaged near the left end portion of the elongated hole 16 D of the third operating link 16 in the drawing presses against the upper surface of the second operating link 13 , such that the second operating link 13 that has been rotated by the release lever 11 is restricted from rotating back (i.e., from rotating counterclockwise).

However, even if the release lever 11 is released (i.e., lowered) while the sliding member 20 is riding on the raised step portion 6 A 6 , the locking device 6 C of the slider devices 6 is kept unlocked, so the seat main body 1 will not lock in the unusable range. However, from this state, the locking device 6 C can be switched to a locked state by operating the walk-in lever, not shown, and flipping the seat cushion 3 up toward the rear so that it is in a tipped up position, which operates the unlocking operation canceling mechanism 30 , to be described later, that brings the slide pin 17 out of the state in which it is pushed against the upper surface of the second operating link 13 , as shown in FIG. 6 .

Next, the structure of the unlocking operation canceling mechanism 30 will be described. The unlocking operation canceling mechanism 30 has a fifth operating link 31 , a sixth operating link 32 , and a seventh operating link 33 , as shown in FIGS. 2 to 3 . Here, the seventh operating link 33 serves as a link that forms the unlocking operation canceling mechanism of the invention. The fifth operating link 31 is rotatably connected to the fixed plate 5 B that is integrated with the base plate 5 , by the connecting shaft 3 A. The sixth operating link 32 is a long link, with the upper end portion in the drawing rotatably connected by a connecting pin 32 A to an end portion of an arm of the fifth operating link 31 that extends farther toward the rear than the connecting shaft 3 A, and the lower end portion in the drawing rotatably connected to the upper end portion of the seventh operating link 33 by the connecting pin 32 B.

The seventh operating link 33 is rotatably connected to the base plate 5 by the connecting shaft 33 A. The elongated hole 33 C that curves in the longitudinal direction of the seventh operating link 33 is formed in a link portion that extends downward in the drawing. The slide pin 17 that is fit into the elongated hole 16 D of the third operating link 16 is interlocked so as to be able to slide along the elongated hole 33 C. The seventh operating link 33 is constantly urged to rotate counterclockwise by the urging force of a tension spring 33 B that is strung between the seventh operating link 33 and the base plate 5 , as shown in FIG. 3 .

When this seventh operating link 33 rotates counterclockwise by the urging force of the tension spring 33 B, the fifth operating link 31 is urged to rotate clockwise via the sixth operating link 32 , and the arm portion 31 A on the left side in the drawing is stopped in a position abutting against an engaging plate 3 F 1 that is integrally formed with the cushion frame 3 F. In the unlocking operation canceling mechanism 30 having the structure described above, as shown in FIG. 6 , when the seat cushion 3 is flipped up to the rear and placed in the tipped up position by operating the walk-in lever, the engaging plate 3 F 1 formed on the cushion frame 3 F moves away from the arm portion 31 A on the left side in the drawing of the fifth operating link 31 , such that the fifth operating link 31 , the sixth operating link 32 , and the seventh operating link 33 each rotate by being pulled on by the urging force of the tension spring 33 B.

More specifically, rotation by the urging of the tension spring 33 B causes the seventh operating link 33 to rotate counterclockwise about the connecting shaft 33 A, such that the slide pin 17 that is fit into the elongated hole 33 C slides along the elongated hole 16 D of the third operating link 16 into a position at the end portion on the right side in the drawing. As a result, the slide pin 17 is brought out of the state in which it is pushed against the upper surface of the second operating line 13 , such that the locking device 6 C that had been unlocked by the release mechanism 15 can be locked.

Therefore, the seat main body 1 can be locked in the unusable range by switching the seat main body 1 to the tipped up position as described above. Incidentally, the seat main body 1 may also be slid from a position in the seat-usable range to a position in the unusable range and then locked, after switching the seat main body 1 to the tipped up position by operating the walk-in lever.

Next, a method for returning the seat main body 1 from a state in which it is in the tipped up position and locked in the unusable range to the original position in which it can be used for sitting on in a position in the seat-usable range will be described. First, the locking device 6 C is unlocked by the release member 15 via the first operating link 12 and the second operating link 13 , by pulling up oh the release lever 11 , as shown in FIG. 7 . This unlocks the seat main body 1 .

Next, the seat main body 1 is slid to the rear with respect to the vehicle until the sliding member 20 drops down off of the raised step portion 6 A 6 of the fixed rail 6 A onto the bottom surface portion 6 A 1 , as shown in FIG. 8 . Accordingly, the operating arm 16 B stops being being pushed up by the sliding member 20 , such that the third operating link 16 is pulled up in the clockwise direction. As a result, even if the seat cushion 3 returns to a sittable position by laying down forward, the locking device 6 C can still be locked by releasing (i.e., lowering) the release lever 11 (see FIG. 9 ).

Incidentally, if the release lever 11 is released and the seat cushion 3 is laid down forward from the tipped up position while the seat main body 1 is being moved from a position in the unusable range in FIG. 7 to a position in the seat-usable range in FIG. 8 , the slide pin 17 will slide to the left in the drawing inside the elongated hole 16 D of the third operating link 16 and abut against the tapered surface 13 A that is slanted upward with respect to the second operating link 13 as the seventh operating link 33 rotates clockwise.

Therefore, when the seat cushion 3 is laid down forward even further from this state, the slide pin 17 slides further to the left in the drawing inside the elongated hole 16 D of the third operating link 16 , and pushes down on the tapered surface 13 A of the second operating link 13 such that the slide pin 17 comes to be in the state shown in FIG. 5 , in which it is riding on the upper surface of the second operating link 13 . That is, as the second operating link 13 is pushed down and around, the release member 15 pushes down on the push plate portion 6 C 2 of the locking device 6 C, thus preventing the seat main body 1 from being locked.

In this way, according to the vehicle seat of this example embodiment, the locking device 6 C that locks the seat main body 1 in the seat-usable range is kept unlocked by the unlocking mechanism 10 operating as a result of the sliding member 20 riding up on the step of the fixed rail 6 A (i.e., the raised step portion 6 A 6 ), when the seat main body 1 is moved into the unusable range. Therefore, the seat main body 1 can be prevented from being used to sit on in the unusable range.

Meanwhile, in the unusable range as well, the seat main body 1 can be locked by switching the seat cushion 3 to the tipped up position, which results in the operation by the unlocking mechanism 10 to unlock the locking device 6 C being canceled by the unlocking operation canceling mechanism 30 . In this way, the seat main body 1 is able to be locked in the seat-usable range, as well as locked in the unusable range by being placed in the tipped up position, using only one type of locking device 6 C.

Also, the slide pin 17 is able to slide while being engaged with the links 16 and 33 , following the movements of these links 16 and 33 , using the mechanism that slides the slide pin 17 inside the elongated holes 16 D and 33 C of the links 16 and 33 as the mechanism by which the operation by the unlocking mechanism 10 to unlock the locking device 6 C is canceled by the unlocking operation canceling mechanism 30 . Thus, the operation by the unlocking mechanism 10 to unlock the locking device 6 C and the operation by the unlocking operation canceling mechanism 30 to cancel this unlocking operation by the unlocking mechanism 10 are able to be stably performed.

Also, the upper surface of the upper plate portion 23 of the sliding member 20 is provided exposed above the slide rail 6 B, so the operating arm 16 B can easily be assembled protruding from the seat main body 1 and facing the upper surface of the sliding mechanism 20 provided inside the slide rail 6 B.

While the invention has been described with reference to one example embodiment thereof, it should be understood that the invention may be carried out in various modes in addition to the example embodiment described above. In the example embodiment described above, the raised step portion 6 A 6 that rises in a step-like manner from the bottom surface portion 6 A 1 of the fixed rail 6 A is given as an example of a step portion on which the sliding member 20 rides in the unusable range. Alternatively, however, the step portion may also be formed as a lowered step portion in which the step portion drops down in step-like manner. Also, the step portion may be formed on the side portion 6 A 2 of the fixed rail 6 A and structured to push the sliding member 20 against the side portion 6 A 2 .

Further, in the example embodiment described above, when the sliding member 20 rides up on the raised step portion 6 A 6 (i.e., the step portion), the sliding member 20 rotates as a result, and pushes up on the operating arm 16 B. Alternatively, however, the structure may be such that the operating arm 16 B operates with linear movement vertically as a result of the sliding member 20 riding on up the step portion. Also, in the example embodiment described above, the unusable range is set to a position in front of the seat-usable range in the longitudinal direction of the vehicle, but the unusable range may alternatively be set to a position to the rear of the seat-usable range in the longitudinal direction of the vehicle.

Also, in the example embodiment described above, a mode in which the seat cushion 3 is hinged at the rear end portion and flips up toward the rear is given as the mode in which the seat cushion 3 is flipped up to the tipped up position. Alternatively, however, the seat cushion 3 may be hinged at the front end portion and flipped up toward the front.