Vehicle seat slide device

A vehicle seat slide device includes an upper rail, a lower rail, a lock mechanism that restricts movement of the upper rail relative to the lower rail, and a lock release mechanism that performs an unlocking action with the lock mechanism. The lock release mechanism includes an input lever and a release lever. The release lever includes a longitudinal extension, a widthwise extension, and a vertical extension. The release lever is configured so that the vertical extension presses an unlock element as the input lever presses the widthwise extension from above.

BACKGROUND

The present disclosure relates to a vehicle seat slide device.

2. Description of Related Art

A typical vehicle seat slide device includes an upper rail, a lower rail, and a lock mechanism. The upper rail supports a seat located above the upper rail. The lower rail supports the upper rail so that the upper rail and lower rail are movable relative to each other. The lock mechanism restricts movement of the upper rail relative to the lower rail. Such a seat slide device may also include a lock release mechanism allowing the lock mechanism to perform an unlocking action based on an operating force input by a transmitting member. Japanese Laid-Open Patent Publication No. 2018-52207 discloses an example of a lock release mechanism that includes a lever member pivoted when pulled by a wire cable that transmits an operating force based on a forward tilting operation of a seat back performed in cooperation with a reclining device. The movement of the upper rail relative to the lower rail is permitted when the lever member presses an unlock element (lock member) of the lock mechanism so that the lock mechanism performs an unlocking action.

The operability of a vehicle seat needs to be improved. Japanese Laid-Open Patent Publication No. 2006-44532 discloses an example of a lock release mechanism that is formed by a combination of a first lever pivoted when pulled by a wire cable and a second lever pivoted when pressed by the first lever. By optimizing the link ratio with such a mechanism, the unlock element can be pressed in a stable manner with a smaller operating force. The use of the lock release mechanism to perform an unlocking action with the lock mechanism improves operability.

However, the arrangement of the two levers as described above occupies a large space. This may adversely affect the mountability on the upper rail. Thus, there is still room for improvement in this respect.

SUMMARY

It is an objective of the present disclosure to provide a vehicle seat slide device that reduces the size of a lock release mechanism while obtaining superior operability.

In a first general aspect, a vehicle seat slide device includes, an upper rail that supports a seat located above the upper rail, a lower rail that supports the upper rail so that the upper rail is movable relative to the lower rail, a lock mechanism that restricts movement of the upper rail relative to the lower rail, and a lock release mechanism that permits movement of the upper rail relative to the lower rail by performing an unlocking action with the lock mechanism based on an operating force received from a transmitting member. The lock release mechanism includes an input lever connected to the transmitting member, and a release lever that presses an unlock element of the lock mechanism and performs the unlocking action with the lock mechanism when pressed and pivoted by the input lever that is pivoted based on the operating force. The release lever includes a longitudinal extension, which extends toward the input lever in a longitudinal direction of the upper rail, a widthwise extension, which extends in a widthwise direction of the upper rail, and a vertical extension, which extends in a vertical direction of the upper rail. The longitudinal extension, the widthwise extension, and the vertical extension are integral. The release lever is configured so that the vertical extension presses the unlock element as the input lever presses the widthwise extension from above.

DETAILED DESCRIPTION

One embodiment of a vehicle seat slide device will now be described with reference to the drawings.

As shown inFIG. 1, a vehicle seat1includes a seat cushion2and a seat back3arranged at the rear end of the seat cushion2in an inclinable manner. Right and left lower rails5, which extend in the front-rear direction of the vehicle (right-left direction inFIG. 1), are arranged on a vehicle floor4. For the sake of brevity, only one of the two lower rails5is shown inFIG. 1and the other drawings. Further, an upper rail6, which moves on the lower rail5relative to the lower rail5in a direction in which the lower rail5extends (longitudinal direction), is attached to each lower rail5. The seat1is supported above the upper rails6.

A vehicle with the seat1of the present embodiment includes a seat slide device10formed by the lower rails5and the upper rails6. The seat slide device10allows positioning of the seat1in the front-rear direction of the vehicle. That is, the seat slide device allows the slide position of the seat1to be adjusted.

Specifically, as shown inFIGS. 2 and 3, the lower rail5includes a substantially flat bottom wall11, which serves as a fixing portion fixed to the vehicle floor4(refer toFIG. 1). An outer wall12extends from the bottom wall11at the ends in the widthwise direction (right-left direction inFIG. 2). The upper ends of the outer walls12(ends at the upper side inFIG. 2) are flanged so that upper walls13extend inward in the widthwise direction. The distal ends of the upper walls13are bent so that inner walls14extend downward.

The upper rail6includes two side walls15, which are opposed to each other in the widthwise direction. The upper rail6also includes a flat upper wall16connecting the side walls15. The upper rail6in the present embodiment is coupled to the lower rail5so that a body17, which is defined by the side walls15and the upper wall16that form a substantially U-shaped cross section, is located between the inner walls14of the lower rail5.

Further, in the upper rail6according to the present embodiment, the lower ends of the side walls15are bent so that bent portions18extend outward in the widthwise direction. The bent portions18are arranged in a space defined by the outer walls12, the upper walls13, and the inner walls14of the lower rail5to restrict movement in the upward and widthwise directions relative to the lower rail5.

Spherical rolling elements (not shown) are located between each outer wall12of the lower rail5and the corresponding bent portions18of the upper rail6, which are opposed to each other in the widthwise direction as described above. The rolling elements contact and roll along the outer walls12of the lower rail5and the bent portions18of the upper rail6so that the upper rail6moves smoothly relative to the lower rail5in the seat slide device10according to the present embodiment.

Further, as shown inFIGS. 3 to 6, the seat slide device10according to the present embodiment includes a lock mechanism20that restricts and allows movement of the upper rail6relative to the lower rail5.

Specifically, the lower rail5according to the present embodiment includes engagement grooves21arranged in the longitudinal direction (right-left direction inFIG. 4Aand direction perpendicular to the planes ofFIGS. 5 and 6). In the lower rail5according to the present embodiment, the engagement grooves21are arranged at equal intervals by cutting out slits in the lower ends of the inner walls14, which extend downward from the distal ends of the upper walls13. The lock mechanism20according to the present embodiment includes a lock spring22that engages the engagement grooves21in a state supported by the upper rail6.

Specifically, the lock spring22according to the present embodiment includes a pair of spring portions25formed by bending a wire into two. The spring portions25of the lock spring22are arranged inside the body17to extend in the longitudinal direction of the upper rail6. Each spring portion25includes a crank-shaped undulation26, which is formed by bending the spring portion25a number of times at a substantially right angle. The undulations26of the lock spring22according to the present embodiment engage the engagement grooves21arranged on the lower rail5.

More specifically, as shown inFIGS. 4A and 4B, the upper rail6according to the present embodiment includes engaging portions27that support the spring portions25of the lock spring22, which is arranged inside the body17, from below. The engaging portions27of the upper rail6according to the present embodiment are formed by partially cutting out the side walls15of the upper rail6and bending the cut-out parts of the side walls15to extend inward in the widthwise direction of the upper rail6. Thus, the engaging portions27extend inward from the side walls15in the U-shaped cross section of the upper rail6.

Further, as shown inFIGS. 3 to 6, the undulations26in the spring portions25of the lock spring22according to the present embodiment include widthwise extensions26x(four in the present embodiment) that extend in the widthwise direction of the upper rail6. The upper rail6according to the present embodiment includes insertion holes28(four in the present embodiment) formed by cutting out slits in lower portions of the side walls15and the bent portions18.

As shown inFIGS. 4A to 5, the lock spring22according to the present embodiment is held by the upper rail6in a state in which the widthwise extensions26x, which are formed by the undulations26of the spring portions25, are arranged inside the insertion holes28, which are formed in the upper rail6. The widthwise extensions26xof the lock spring22projecting outward from the body17in the widthwise direction of the upper rail6through the insertion holes28are arranged in the engagement grooves21formed in the lower rail5. Thus, the lock spring22, which is held by the upper rail6, engages the engagement grooves21of the lower rail5so that the lock mechanism20according to the present embodiment restricts movement of the upper rail6relative to the lower rail5in the longitudinal direction, or the slide movement of the seat1.

As shown inFIGS. 3 to 6, the lock mechanism20according to the present embodiment includes an unlock lever30having the form of a substantially elongated bar extending in the longitudinal direction of the upper rail6. Further, the lock mechanism20according to the present embodiment includes a loop handle31(refer toFIG. 1) connected to the unlock lever30in a state located frontward from the seat1. The lock mechanism20according to the present embodiment disengages the lock spring22from the engagement grooves21of the lower rail5when an operating force is input to the loop handle31and transmitted to the lock spring22by the unlock lever30.

Specifically, as shown inFIG. 4A, the unlock lever30according to the present embodiment overlaps the lock spring22, which is arranged inside the body17, from above at a first end6aof the upper rail6located at the front side of the vehicle (left side inFIG. 4A).

Further, the unlock lever30according to the present embodiment includes a projection35that defines a pivotal fulcrum30xof the unlock lever30when abutting against the upper wall16of the upper rail6from below (lower side inFIG. 4A). A first end30aof the unlock lever30located at the first end6aof the upper rail6is connected to an inserted portion31xof the loop handle31that is inserted into the body17from the first end6aof the upper rail6. A second end30bof the unlock lever30according to the present embodiment, which is located toward the rear of the vehicle, is arranged above the undulations26of the spring portions25of the lock spring22.

With the lock mechanism20according to the present embodiment, when the loop handle31is lifted, the first end30aof the unlock lever30connected to the loop handle31is moved upward. This pivots the unlock lever30about the pivotal fulcrum30x(clockwise inFIG. 4A). Further, as shown inFIG. 6, the pivoting downwardly moves the second end30bof the unlock lever30, which lowers the lock spring22in abutment with the bent undulations26of the spring portions25. This flexes the lock spring22so that the lock mechanism20according to the present embodiment disengages the lock spring22from the engagement grooves21of the lower rail5.

The seat slide device10according to the present embodiment allows for adjustment of the slide position of the seat1with the lock mechanism20by keeping the loop handle31lifted. When the user releases the loop handle31, the seat1can be fixed at the desired slide position.

Lock Release Mechanism

A lock release mechanism of the seat slide device10according to the present embodiment will now be described.

As shown inFIG. 1, the seat slide device10according to the present embodiment includes a lock release mechanism40that cooperates with a reclining device (recliner)39to perform an unlocking action with the lock mechanism20when an operation unit38arranged on the seat1is operated.

Specifically, the seat1according to the present embodiment includes a foot lever41, which serves as the operation unit38, at the rear lower side of the seat cushion2. Further, the reclining device39of the seat1according to the present embodiment tilts the seat back3forward when the foot lever41is operated. An operating force input to the foot lever41is transmitted by a wire cable42to the lock release mechanism40arranged in the seat slide device10. This implements a walk-in function that allows for adjustment of the slide position of the seat1according to the present embodiment while the seat back3is tilted forward.

As shown inFIGS. 7 to 11, the lock release mechanism40according to the present embodiment includes an input lever51and a release lever52. The input lever51is pivoted by an operating force received from the wire cable42. The release lever52is pressed and pivoted by the input lever51so that the lock mechanism20performs an unlocking action. The lock release mechanism40according to the present embodiment includes a support bracket53fixed to the upper rail6in a state pivotally supporting the input lever51and the release lever52.

Specifically, the support bracket53according to the present embodiment includes a substantially flat base54fixed to the upper wall16of the upper rail6from above (upper side inFIGS. 7 and 9) and support walls55,56that extend from one end of the base54. The support bracket53of the seat slide device10according to the present embodiment is formed by processing a sheet of metal. Further, the support bracket53according to the present embodiment includes holes57,58that extend through the support walls55,56in the thickness direction (vertical direction inFIG. 8, right-left direction inFIG. 9). Shaft members (hinge pins)61,62are fitted into the holes57,58to serve as support shafts51x,52xof the input lever51and the release lever52, respectively.

The input lever51and the release lever52according to the present embodiment include insertion holes63,64into which the shaft members (hinge pins)61,62are inserted, respectively. Thus, the input lever51is supported pivotally about the support shaft51xdefined by the shaft member61, which is supported by the support wall55, and the release lever52is supported pivotally about the support shaft52xdefined by the shaft member62, which is supported by the support wall56.

Further, the base54of the support bracket53according to the present embodiment is fixed to the upper wall16of the upper rail6so that the input lever51and the release lever52supported by the support walls55,56are lined in the longitudinal direction (right-left directions inFIGS. 7 and 8and direction perpendicular to plane ofFIG. 9) of the upper rail6, namely, in the front-rear direction of the vehicle. Specifically, the support bracket53is fixed to the upper rail6so that the input lever51supported by the support wall55is arranged toward a second end6bof the upper rail6(right sides inFIGS. 7 and 8, right sides inFIGS. 3, 4A, and 4B) from the release lever52supported by the support wall56, that is, toward the rear side of the vehicle. The support walls55,56of the support bracket53according to the present embodiment pivotally support the input lever51and the release lever52at an outer side of the support walls55,56in the widthwise direction of the upper rail6(lower side inFIG. 8and left side inFIG. 9).

The input lever51and the release lever52of the seat slide device10according to the present embodiment are formed by processing a sheet of metal. The support bracket53is fixed to the upper wall16of the upper rail6using a rivet65(POP rivet).

Further, in a state in which the support bracket53according to the present embodiment is fixed to the upper rail6, the insertion hole63of the input lever51, which is supported by the support wall55, and the insertion hole64of the release lever52, which is supported by the support wall56, are both located at positions separated outward in the widthwise direction from the body17of the upper rail6. With the lock release mechanism40according to the present embodiment, interference of the input lever51and the release lever52, which are supported by the support bracket53, and the wire cable42, which is connected to the input lever51, with the upper rail6(and lower rail5) is limited.

More specifically, the input lever51according to the present embodiment includes a first extension71that extends downward (toward lower side inFIG. 7) and has a hole70(connection portion) in a distal end71ato which the wire cable42is connected. The input lever51according to the present embodiment is pivoted (counterclockwise inFIG. 7) when the first extension71is pulled by the wire cable42. Specifically, the distal end71aof the first extension71is bent to be substantially L-shaped and extend toward the first end6aof the upper rail6, that is, toward the front of the vehicle (leftward inFIGS. 7 and 8, leftward inFIGS. 3 and 4A). Thus, with the input lever51according to the present embodiment, the distal end71ato which the wire cable42is connected is located at a position closer to the release lever52.

Further, the input lever51according to the present embodiment includes a second extension72located on the side of the support shaft51xopposite to the first extension71. Specifically, the second extension72has the form of a crank and extends toward the first end6aof the upper rail6, inward in the widthwise direction (upper side inFIG. 8, right side inFIG. 9), and then toward the first end6aagain. The cranked form of the second extension72of the input lever51according to the present embodiment is obtained through a bending process. When the input lever51according to the present embodiment is pulled and pivoted by the wire cable42, a distal end72aof the second extension72of presses the release lever52.

The release lever52according to the present embodiment includes a longitudinal extension73extending in the longitudinal direction of the upper rail6toward the rear side of the vehicle, more specifically, toward the input lever51, which is located toward the second end6bof the upper rail6in a state in which the support bracket53is fixed to the upper wall16of the upper rail6. The release lever52includes a widthwise extension74, which extends in the widthwise direction of the upper rail6, and a vertical extension75, which extends in the vertical direction.

Specifically, as shown inFIGS. 12A to 12C, the release lever52according to the present embodiment includes the insertion hole64in a proximal end73bof the longitudinal extension73. The shaft member62serving as the support shaft52xis inserted into the insertion hole64. The widthwise extension74and the vertical extension75are arranged at a distal end73aof the longitudinal extension73.

The widthwise extension74is continuous with an upper end73cof the longitudinal extension73and extends toward one side (right side inFIG. 12B, upper side inFIG. 12C) in the thickness direction of the longitudinal extension73. The vertical extension75is continuous with a distal end74aof the widthwise extension74, spaced apart from the longitudinal extension73, and extended downward (toward lower sides inFIGS. 12A and 12B). The longitudinal extension73, the widthwise extension74, and the vertical extension75of the release lever52according to the present embodiment are formed by the same plate through a bending process. When viewed in the longitudinal direction of the upper rail6(when viewed from, for example, input lever51), the longitudinal extension73, the widthwise extension74, and the vertical extension75of the release lever52according to the present embodiment form a substantially U-shape that is open downward.

More specifically, as shown inFIGS. 7 to 9, the release lever52according to the present embodiment is supported by the support bracket53so that the distal end72aof the second extension72of the input lever51is arranged above the widthwise extension74. The upper wall16of the upper rail6according to the present embodiment includes a hole76(insertion hole), which is open upward. The support bracket53according to the present embodiment also includes a hole53xarranged above the hole76when the support bracket53is fixed to the upper wall16of the upper rail6. The release lever52according to the present embodiment is supported by the support bracket53so that a distal end75aof the vertical extension75is inserted into the hole76.

As shown inFIGS. 13A to 13C, with the lock release mechanism40according to the present embodiment, when the input lever51is pulled and pivoted (counterclockwise inFIGS. 13A to 13C) by the wire cable42, the second extension72(i.e., distal end72a) of the input lever51presses the widthwise extension74of the release lever52from above (upper side inFIGS. 13A to 13C). This pivots (clockwise inFIGS. 13A to 13B) the release lever52and downwardly moves the vertical extension75(i.e., lower end75a), which is inserted into the upper rail6(i.e., body17), through the hole76, which extends through the upper wall16. The lock release mechanism40according to the present embodiment performs an unlocking action with the lock mechanism20when the downwardly moved vertical extension75of the release lever52presses the unlock lever30located inside the upper rail6(i.e., body17).

Specifically, the projection35of the unlock lever30according to the present embodiment defines the pivotal fulcrum30xabutting against the upper wall16of the upper rail6from below. When the unlock lever30is pivoted about the pivotal fulcrum30xand the second end30bis moved downward, a pressing portion37arranged at the second end30bpresses the lock spring22, which is engaged with the lower rail5. The lock mechanism20according to the present embodiment performs an unlocking action when the flexed lock spring22is disengaged from the lower rail5(refer toFIGS. 5 and 6).

With the lock release mechanism40according to the present embodiment, the vertical extension75of the release lever52is configured to press the unlock lever30from above, which serves as an unlock element of the lock mechanism20, at the second end30bin the longitudinal direction from the pivotal fulcrum30xof the unlock lever30. The second end30b, which is located above the lock spring22, pivots and downwardly moves (FIGS. 13A to 13C, clockwise) the unlock lever30in a direction that results in the lock mechanism20performing an unlocking action.

Further, as shown inFIG. 9, in the lock release mechanism40according to the present embodiment, the wall (15,16) of the upper rail6located at the side (left side inFIG. 9) of the hole76, which extends through the upper wall16, that is closer to the support wall56of the release lever52is located between the longitudinal extension73and the vertical extension75of the release lever52in the widthwise direction of the upper rail6. The release lever52according to the present embodiment is configured to pivot so that the walls (15,16) of the upper rail6are arranged inside the U-shape, which is open downward and is substantially formed by the longitudinal extension73, the widthwise extension74, and the vertical extension75.

The release lever52according to the present embodiment is formed so that the vertical extension75is spaced apart from the longitudinal extension73in the widthwise direction of the upper rail6. The lock release mechanism40according to the present embodiment is formed so that the release lever52is pivotally supported with the widthwise extension74located above the side wall15and the upper wall16of the upper rail6that are located between the vertical extension75and the longitudinal extension73. The lock release mechanism40according to the present embodiment allows the support shaft52xof the release lever52to be set at a low position while avoiding interference between the release lever52and the upper rail6.

As shown inFIG. 8, the release lever52of the present embodiment is pivotally supported by the outer side of support wall56in the widthwise direction of the upper rail6(lower side inFIG. 8). At position74xat which the widthwise extension74is pressed by the input lever51, the release lever52is located at the inner side of the support wall56in the widthwise direction (upper side inFIG. 8). Thus, in a state in which position74x, which is where the widthwise extension74is pressed by the input lever51, is arranged in a region facing a first surface56aof the support wall56, the release lever52is pivotally supported by the support shaft52x, which is supported by the support wall56on a second surface56bof the support wall56, which is opposite to the first surface56a. With the lock release mechanism40according to the present embodiment, when the widthwise extension74is pressed by the input lever51, tilting of the release lever52in the widthwise direction of the upper rail6is limited and the release lever52can be smoothly pivoted.

As shown inFIGS. 11 and 13A to 13C, the lock release mechanism40according to the present embodiment includes a torsion coil spring78fitted onto the shaft member62, which serves as the support shaft52xof the release lever52. The lock release mechanism40urges the release lever52with the elastic force of the torsion coil spring78in a direction (counterclockwise inFIGS. 13A to 13C) opposite to the pivoting direction (clockwise inFIG. 13A to 13C) when pressed by the input lever51.

Specifically, the torsion coil spring78according to the present embodiment has one end engaged with an engaging portion79arranged on the base54of the support bracket53and another end engaged with a hole80extending through the longitudinal extension73of the release lever52. The lock release mechanism40according to the present embodiment returns the release lever52with the urging force (elastic force) of the torsion coil spring78to initial position NO at which the vertical extension75does not press the unlock lever30as shown inFIG. 13Awhen an operating force is no longer input to the input lever51by the wire cable42.

The seat1according to the present embodiment is in a state in which the wire cable42does not pull the input lever51when the foot lever41(refer toFIG. 1) is operated to raise the seat back3that has been tilted forward. With the lock release mechanism40according to the present embodiment, when the input lever51does not press the release lever52, the release lever52is returned to initial position NO with the urging force of the torsion coil spring78. The seat slide device10according to the present embodiment fixes the slide position of the seat1when the lock mechanism20returns to a lock state in which the movement of the upper rail6relative to the lower rail5is restricted.

Further, the release lever52of the lock release mechanism40according to the present embodiment, which is pivoted by the urging force of the torsion coil spring78, presses and pivots (clockwise inFIGS. 13A to 13C) the input lever51to return the input lever51to initial position MO at which the wire cable42does not pull the input lever51. This allows the input lever51and the release lever52to be smoothly pivoted so that the lock mechanism20can readily perform an unlocking action when an operating force is input by the wire cable42again.

The support bracket53according to the present embodiment includes an engaging portion81engaged with the wire cable42connected to the input lever51in addition to the engaging portion79, which is engaged with one end of the torsion coil spring78. This allows the lock release mechanism40according to the present embodiment to be coupled to the upper rail6in a state in which the input lever51, the release lever52, the torsion coil spring78, and a connected end of the wire cable42are integrally held by the support bracket53.

The advantages of the present embodiment will now be described.

(1) The lock release mechanism40includes the input lever51and the release lever52. The input lever51is pivoted by an operating force received from the wire cable42, which serves as a transmitting member. The release lever52presses the unlock lever30and unlocks the lock mechanism20when pressed and pivoted by the input lever51. The longitudinal extension73of the release lever52, which extends toward the input lever51in the longitudinal direction of the upper rail6integrally includes the widthwise extension74, which extends in the widthwise direction of the upper rail6, and the vertical extension75, which extends in the vertical direction. When the widthwise extension74of the release lever52is pressed by the input lever51from above, the vertical extension75presses the unlock lever30, which is located below the input lever51and serves as an unlock element.

According to the above structure, the release lever52pressed by the input lever51presses the unlock lever30of the lock mechanism20. This obtains superior operability. The position where the input lever51presses the release lever52and the position where the release lever52presses the unlock lever30of the lock mechanism20are both located between the support shaft51xof the input lever51and the support shaft52xof the release lever52, which are lined in the longitudinal direction of the upper rail6. This allows the lock release mechanism40to be reduced in size in the longitudinal direction of the upper rail6.

Further, the structure in which the longitudinal extension73integrally includes the widthwise extension74and the vertical extension75increases the degree of freedom for the location of the release lever52. This further improves the characteristics for mounting the lock release mechanism40on the upper rail6while allowing for reduction in the size of the lock release mechanism40.

The widthwise extension74of the release lever52serves as a pressed portion for the input lever51so that the input lever51can press the release lever52in a stable manner. Further, the vertical extension75serves as a pressing portion for the unlock lever30so that a contact angle (angle of friction) when the release lever52presses the unlock lever30can be adjusted to be a substantially right angle. This avoids situations in which the release lever52becomes fixed and caught in the unlock lever30due to friction resulting from pressing.

(2) The upper rail6includes the two side walls15, which are opposed to each other in the widthwise direction of the upper rail6, and the upper wall16, which connects the side walls15. In the lock release mechanism40, the vertical extension75of the release lever52is configured to press the unlock lever30, which is located below the upper wall16, through the hole76extending through the upper wall16of the upper rail6.

According to the above structure, the lock release mechanism40is easily coupled to the upper rail6with the input lever51and the release lever52located outside the upper rail6. Further, the vertical extension75of the release lever52is inserted into the hole76extending through the upper wall16of the upper rail6so that the size of the hole76can be minimized. This maintains the rigidity of the upper rail6in a preferred manner.

(3) The vertical extension75of the release lever52is spaced apart from the longitudinal extension73in the widthwise direction of the upper rail6. The release lever52of the lock release mechanism40is pivoted so that the widthwise extension74is arranged above the side wall15and the upper wall16of the upper rail6between the vertical extension75and the longitudinal extension73of the release lever52.

The above structure allows the support shaft52xof the release lever52to be located at a lower position while avoiding interference between the release lever52and the upper rail6. This further improves the characteristics for mounting the lock release mechanism40on the upper rail6while allowing for reduction in the size of the lock release mechanism40.

(4) The release lever52includes the widthwise extension74, which is continuous with the upper end73cof the longitudinal extension73, and the vertical extension75, which is continuous with the distal end74aof the widthwise extension74that is spaced apart from the longitudinal extension73.

According to the above structure, the release lever52, in which the longitudinal extension73is integral with the widthwise extension74and the vertical extension75, is easily formed by bending a plate or the like. When the release lever52is viewed in the longitudinal direction of the upper rail6, the longitudinal extension73, the widthwise extension74, and the vertical extension75form a substantially U-shape that is open downward. The release lever52is arranged as described in advantages (2) and (3) so that this further improves the characteristics for mounting the lock release mechanism40on the upper rail6while allowing for reduction in the size of the lock release mechanism40.

(5) The lock release mechanism40includes the support bracket53fixed to the upper rail6while pivotally supporting the input lever51and the release lever52. This easily couples the lock release mechanism40to the upper rail6.

(6) The support bracket53includes the support wall56pivotally supporting the support shaft52xof the release lever52. In a state in which position74x, which is where the widthwise extension74is pressed by the input lever51, is arranged in the region facing the first surface56aof the support wall56, the release lever52is pivotally supported on a second surface56bof the support wall56, which is opposite to the first surface56a.

According to the above structure, when the widthwise extension74is pressed by the input lever51, tilting of the release lever52relative to the widthwise direction of the upper rail6is limited. Thus, the release lever52is smoothly pivoted and the lock release mechanism40is stably actuated.

(7) The lock release mechanism40includes the torsion coil spring78, which serves as an urging member. The torsion coil spring78urges the release lever52in a direction opposite to the direction in which the release lever52is pivoted when pressed by the input lever51. The release lever52of the lock release mechanism40, which is pivoted by the urging force (elastic force) of the torsion coil spring78, presses the pivoted input lever51so that the input lever51returns to initial position MO where no operating force is input by the wire cable42.

According to the above structure, a return spring or the like that returns the input lever51to initial position MO is omitted thereby reducing the number of parts. Further, the input lever51and the release lever52are maintained in a state in which the urging force of the torsion coil spring78abuts the input lever51and the release lever52against each other. This reduces noise that would be generated when loosening occurs.

The above illustrated embodiment may be modified as described below. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other.

In the above embodiment, the unlock lever30of the lock mechanism20that performs an unlocking action with the lock mechanism20by lowering and disengaging the lock spring22from the lower rail5serves as an unlock element, and the unlock lever30is pressed by the vertical extension75of the release lever52. Instead, the lock spring22of the lock mechanism20may serve as an unlock element, and the lock spring22may be pressed by the release lever52of the lock release mechanism40. That is, the unlock element may be of any member of the lock mechanism20as long as it allows the lock mechanism20to perform an unlocking action when the unlock element is pressed by the vertical extension75of the release lever52. In the lock mechanism that includes a lock member engaged with, for example, the lower rail5, the lock member may serve as the unlock element. The structure of the lock mechanism may also be modified so that such a lock member is pressed by the vertical extension75of the release lever52.

In the above embodiment, when the release lever52is viewed in the longitudinal direction of the upper rail6, the longitudinal extension73, the widthwise extension74, and the vertical extension75substantially form a U-shape, which is open downward. Instead, the arrangement of the longitudinal extension73, the widthwise extension74, and the vertical extension75may be modified as long as the release lever52has a structure in which the longitudinal extension73is integral with the widthwise extension74and the vertical extension75.

The vertical extension75may extend continuously to the longitudinal extension73. The vertical extension75may extend continuously to a side end portion of the widthwise extension74, which is located in the longitudinal direction of the upper rail6. The widthwise extension74may extend continuously to the lower end of the vertical extension75. When the release lever52is viewed in the longitudinal direction of the upper rail6, the longitudinal extension73, the widthwise extension74, and the vertical extension75may have a T-shaped form, a crank-shaped form, or the like.

In the above embodiment, the support bracket53is fixed to the upper wall16of the upper rail6. Instead, the support bracket53may be fixed to the side wall15. The support wall55of the input lever51and the support wall56of the release lever52do not necessarily have to be arranged at positions located outward in the widthwise direction from the upper rail6.

In the above embodiment, the input lever51is located closer to the second end6bof the upper rail6than the release lever52, that is, toward the rear of the vehicle. Instead, the release lever52may be located toward the rear of the vehicle from the input lever51.

The support bracket53includes the support wall55of the input lever51, the support wall56of the release lever52, the engaging portion79of the torsion coil spring78, and the engaging portion81of the wire cable42. Instead, at least one member of the lock release mechanism40may be directly supported by the upper rail6with the side walls15,16(for example, by cutting out a holding portion).

In the above embodiment, the wire cable42that transmits an operating force as a pulling force is used as the transmitting member that inputs the operating force to the input lever51. Instead, a transmitting member that can transmit the operating force as a pressing force may be used.

In the above embodiment, the torsion coil spring78is used as the urging member of the release lever52. Instead, a compression spring or a tension spring may be used.

In the above embodiment, the lock release mechanism40is connected to the foot lever41arranged at the rear lower side of the seat cushion2. Instead, the lock release mechanism40may be connected to the operation unit38arranged at another portion of the seat1, such as an operation lever arranged near the shoulder of the seat back3.