Seat lifter device

A seat lifter device includes: an output shaft; a support unit that supports the output shaft; an input unit; a ratchet-type feed unit configured to transmit rotation of the input unit to the output shaft; a lock unit configured to lock rotation of the output shaft relative to the support unit; a friction generation unit configured to apply a friction force between a rotation member and the support unit in response to an operation of the input unit rotating in a direction in which the seat is lowered; and a slippage preventing unit. When the input unit rotates in the direction in which the seat is lowered and the output shaft rotates preceding to the feed unit against the friction force to slip, the slippage preventing unit is fitted to the support unit by an elastic force in response to slippage of the output shaft to stop the slippage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2020-187133 filed on Nov. 10, 2020, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a seat lifter device. Specifically, the present disclosure relates to a seat lifter device including an output shaft that raises and lowers a seat in accordance with a rotational operation amount of an operation handle.

BACKGROUND

A vehicle seat disclosed in JP-A-2016-78850 includes a seat lifter device that can adjust a seat surface height of a seat cushion. Specifically, the seat lifter device transmits an operational movement amount of an operation handle as a feed rotation movement amount of a gear by pulling the operation handle upward and pushing the operation handle downward to raise and lower the seat surface height by a certain amount each time. When the operation of the operation handle is released, the seat lifter device locks the rotation of the gear in its position and returns the operation handle to a neutral position before the operation by biasing the operation handle, so that the seat lifter device returns to an initial state in which the operation handle can be re-operated.

The feed rotation of the gear accompanying the operation of the operation handle is performed by pushing a feed claw meshed with the gear in the operation direction of the operation handle. The rotation of the gear is locked as follows when the operation of the operation handle is released. That is, a lock pawl, which includes a pair of symmetrical structures meshed with the gear, has a ratchet meshing structure in which one symmetrical structure is unmeshed accompanying the operation of the operation handle and the other symmetrical structure releases the rotation in the feed direction and bites in the opposite direction. When the operation of the operation handle is released, the other symmetrical structure stops the rotation of the gear in its position.

Similar to the lock pawl, the feed claw that performs the feed rotation of the gear includes a pair of symmetrical structures to allow the movement of returning the operation handle to the neutral position when the operation of the operation handle is released. The feed pawl has a ratchet meshing structure in which one symmetrical structure is unmeshed from the gear accompanying the operation of the operation handle and the other symmetrical structure meshes with the gear to transmit power in the feed direction and releases rotation in the opposite direction.

SUMMARY

In the related art described above, a friction force is constantly applied to an output shaft to prevent the output shaft from slipping due to the weight of the seat when the operation handle is pulled downward. However, when an excessive load exceeding the friction force is input to the seat, the seat may be lowered beyond a rotational operation amount of the operation handle. The present disclosure may provide a seat lifter device that can appropriately stop a seat from slipping when the seat is lowered.

One illustrative aspect of the present disclosure provides a seat lifter device including an output shaft configured to raise and lower a seat in accordance with a rotational operation amount of an operation handle. The seat lifter device includes a support unit that supports the output shaft such that the output shaft is rotatable, and an input unit rotatably coupled to the support unit and integrally coupled to the operation handle. The seat lifter device further includes a feed unit that transmits rotation of the input unit to the output shaft, and a lock unit that locks rotation of the output shaft relative to the support unit. The seat lifter device further includes a friction generation unit provided between the support unit and a rotation member configured to rotate together with the output shaft, and a slippage preventing unit provided in a power transmission path between the output shaft and the feed unit.

The feed unit is of a ratchet type, transmits bidirectional rotation of the input unit from a neutral position to the output shaft, and does not transmit rotation of the input unit returning to the neutral position to the output shaft. The lock unit unlocks the output shaft in response to an operation of the input unit rotating from the neutral position, and locks the rotation of the output shaft in response to an operation of the input unit returning to the neutral position. The friction generation unit applies a friction force between the rotation member and the support unit in response to the operation of the input unit rotating in a direction in which the seat is lowered, thereby stopping preceding rotation of the output shaft due to a weight of the seat. The slippage preventing unit transmits rotation of the feed unit to the output shaft by the operation of the input unit rotating from the neutral position. When the input unit rotates in the direction in which the seat is lowered and the output shaft rotates preceding to the feed unit against the friction force of the friction generation unit to slip, the slippage preventing unit is fitted to the support unit by an elastic force in response to the slippage of the output shaft to stop the slippage.

According to the above-described configuration, when the input unit is rotated in the direction in which the seat is lowered, the lock unit is unlocked and the output shaft is fed in a rotation direction in which the seat is lowered via the feed unit. At this time, the output shaft is prevented from slipping due to the weight of the seat by the friction generation unit. Even when an excessive load in a downward rotation direction that exceeds the friction force of the friction generation unit is input to the output shaft from an output side, the slippage preventing unit is fitted to the support unit so that a slip rotation is prevented. Therefore, it is possible to appropriately stop the slippage of the seat when the seat is lowered.

DETAILED DESCRIPTION

First Embodiment

First, a configuration of a seat lifter device10according to the first embodiment of the present disclosure will be described with reference toFIGS.1to38. In the following description, a forward direction, a rearward direction, an upward direction, a downward direction, a leftward direction, and a rightward direction refer to directions illustrated in the drawings. The term “seat width direction” refers to a left-right direction of a seat1to be described later. Further, in the following description, when no specific reference view is illustrated or when there is no corresponding reference numeral in a reference view, one ofFIGS.1to16is appropriately referred to.

{Schematic Configuration of Seat Lifter Device10}

The seat lifter device10according to the present embodiment is applied to the seat1of an automobile. As illustrated inFIGS.1and2, the seat1includes a seat back2that is a backrest portion for a seated occupant and a seat cushion3that is a seat portion. The seat back2is coupled to a rear end portion of the seat cushion3via a recliner (not illustrated) such that a backrest angle is adjustable. The seat cushion3is coupled to a floor F of the vehicle via a seat slide device4, which includes a pair of left and right rail structures, such that the position of the seat cushion3in a front-rear direction is adjustable.

The seat lifter device10including a pair of left and right link structures is coupled between the seat cushion3and the seat slide device4including a pair of left and right rail structures. By the coupling of the seat lifter device10, the position of the seat cushion3in the height direction relative to the floor F is also adjustable.

The seat slide device4is a known device and includes a pair of left and right lower rails4aextending in the front-rear direction, and a pair of left and right upper rails4bassembled to the respective left and right lower rails4ato be slidable in the front-rear direction. Each of the pair of left and right lower rails4ais fixed to the floor F via a pair of front and rear legs4c.

The seat lifter device10includes a support bracket14fixed to each of the upper rails4b, and a pair of front and rear link members11coupled between the support bracket14and a corresponding side frame3aof the seat cushion3. By the coupling, the seat lifter device10includes a pair of left and right four-joint link mechanisms12in which the pair of front and rear link members11perform a link movement between the side frame3aand the support bracket14on left and right sides.

As illustrated inFIG.2, of the front, rear, left, and right four link members11, the right rear link member11is formed with a sector gear11athat meshes with a pinion gear22aof a rotation control device18attached to the right side frame3a. With the above-described configuration, the right rear link member11receives the transmission of a rotational driving force from the pinion gear22aand performs the link movement. An upper end portion of the right rear link member11is rotatably coupled to the right side frame3avia a torque rod17.

The torque rod17is integrally bridged between an upper end portion of the right rear link member11and an upper end portion of the left rear side link member11to synchronously drive and rotate the two link members11. When the rear link members11perform the link movement simultaneously, the front link members1I constituting the four-bar link mechanisms12also perform the link movement synchronously. Accordingly, the position of the seat cushion3in a height direction relative to the floor F is adjusted.

The rotation control device18is assembled to a right side portion of the right side frame3a. Specifically, the rotation control device18is assembled to the side frame3ain a state in which the pinion gear22ais inserted through a through hole3alformed in the right side frame3aand is meshed with the sector gear11alocated on a left side of the side frame3a. As illustrated inFIG.3, an operation handle5extending forward is assembled to the rotation control device18.

The operation handle5extends forward from a right rear portion of the seat cushion3and allows a user to pull the operation handle5upward and push the operation handle5downward from a neutral position. When the operation handle5is pulled upward and pushed downward from the neutral position, a rotational force corresponding to a movement amount in a corresponding operation direction is input to the rotation control device18. Accordingly, the rotational force in the corresponding operation direction is transmitted to the pinion gear22aformed on an output shaft22of the rotation control device18and the right rear link member11is moved in a rotation direction corresponding to the operation direction.

Specifically, the rotation control device18constantly keeps the operation handle5in the neutral position and prevents the output shaft22from rotating before the operation handle5is operated. When the operation handle5is pulled upward from the neutral position, the rotation control device18outputs to the pinion gear22aa rotational force in a direction in which the right rear link member11is raised forward. Accordingly, the seat cushion3is pulled upward from the floor F.

When the operation handle5is pushed down from the neutral position, the rotation control device18outputs to the pinion gear22aa rotational force in a direction in which the right rear link member11is tilted rearward. Accordingly, the seat cushion3is pushed downward toward the floor F. After the operation handle5is pulled upward and pushed downward from the neutral position, the operation state of the operation handle5is released. Accordingly, the rotation control device18operates to stop the pinion gear22ain its rotation position and to return the operation handle5to the neutral position.

{Schematic Configuration of Rotation Control Device18}

Hereinafter, a specific configuration of the rotation control device18will be described with reference toFIGS.4to38. All members constituting the rotation control device18are pressed metal members.

As illustrated inFIGS.4to8, the rotation control device18is a substantially disk-shaped unit whose axial direction is oriented in the seat width direction. Specifically, as illustrated inFIGS.9to12, the rotation control device18includes an input unit N that is integrally assembled with the operation handle5(seeFIG.3) and a support unit S that is integrally assembled with the right side frame3a(seeFIG.3).

The rotation control device18includes the output shaft22that receives a rotational force transmitted from the input unit N, and a feed unit A that transmits the rotational force from the input unit N to the output shaft22. The rotation control device18further includes a lock unit B that locks the rotation of the output shaft22when no rotational force is transmitted from the input unit N, and a speed increasing unit U that increases the speed of the rotation of the output shaft22and transmits the rotation to a power transmission path between the lock unit B and the speed increasing unit U. The rotation control device18further includes a friction generation unit G that applies a friction force to the rotation of the output shaft22, and a slippage preventing unit D that prevents the output shaft22from slipping during downward rotation.

Configurations of the above-described units will be described in detail. The input unit N includes an outer lever41and an inner lever53each having a substantially disk shape. The outer lever41and the inner lever53are integrally assembled side by side on a central axis C extending in the seat width direction with a cover24, which will be described later, interposed therebetween.

The support unit S includes a substantially disk-shaped body base23, a substantially ring plate-shaped intermediate base25, and the substantially disk-shaped cover24. The body base23, the intermediate base25, and the cover24are integrally assembled side by side in order on the central axis C extending in the seat width direction.

The feed unit A includes four feed claws52, a substantially disk-shaped rotation transmission plate36, and a substantially disk-shaped output plate75. The four feed claws52are rotatably assembled to the inner lever53. The rotation transmission plate36and the inner lever53are assembled side by side on the central axis C extending in the seat width direction and are relatively rotatable around the central axis C.

The rotation transmission plate36is assembled to the output plate75such that the output plate75can be rotated together in the rotation direction. The output shaft22is inserted into a central portion (portion through which the central axis C passes) of the output plate75and is integrally assembled with the output plate75.

As illustrated inFIG.17, the rotation transmission plate36is joined to the inner lever53to be integrated with the inner lever53in the rotation direction by meshing the four feed claws52with an internal gear36aformed on an outer peripheral portion of the rotation transmission plate36. As illustrated inFIGS.19and24, when the inner lever53is rotated in either direction from the neutral position, a corresponding pair of the four feed claws52to be described later are unmeshed from the internal gear36a, and the rotation transmission plate36is fed in the rotation direction of the inner lever53by the meshing with the remaining pair of feed claws52.

By the rotation described above, the rotation transmission plate36feeds the output shaft22coupled via the output plate75in the corresponding rotation direction. As illustrated inFIGS.22and27, when the rotation of the operated inner lever53is returned, the rotation transmission plate36returns only the inner lever53to an initial position (neutral position) before the operation while the rotation transmission plate36itself remains in the position to which the rotation transmission plate36is rotated. That is, as illustrated inFIGS.19and24, when the inner lever53is rotated from the neutral position in either direction, the rotation transmission plate36is fed in the corresponding rotation direction. Then, the rotation transmission plate36is once locked by the output shaft22being locked by the lock unit B in the position where the above-described operation is stopped.

However, as illustrated inFIGS.22and27, when the inner lever53is returned from the position where the rotation transmission plate36is locked to the initial position (neutral position) before the operation, the rotation transmission plate36returns only the inner lever53to the initial position before the operation together with the corresponding feed claws52by sliding the pair of feed claws52meshing with the rotation transmission plate36, while the rotation transmission plate36itself remains in the lock position.

As illustrated inFIGS.10and12, the lock unit B includes four pawls32and a substantially disk-shaped rotation plate37. The four pawls32are rotatably assembled to the intermediate base25. The rotation plate37is gear-coupled to the output shaft22via a planetary gear mechanism64constituting the speed increasing unit U to transmit power. As illustrated inFIG.18, the four pawls32lock the rotation of the rotation plate37relative to the intermediate base25by meshing with an internal gear37aformed on an outer peripheral portion of the rotation plate37.

The rotation of the output shaft22, which is gear-coupled to the rotation plate37, is locked by the locking described above. As illustrated inFIGS.20and25, when the outer lever41is rotated from the neutral position in either direction, a corresponding pair of pawls32of the four pawls32are unmeshed from the internal gear37aof the rotation plate37via a control plate56to be described later. Accordingly, the remaining pair of pawls32of the four pawls32are in a state in which the rotation plate37is allowed to rotate in the corresponding direction, and a state in which the rotation plate37and the output shaft22are allowed to rotate in the corresponding direction, as illustrated inFIGS.21and26.

When the rotation of the operated outer lever41is returned, the pair of pawls32meshing with the internal gear37aof the four pawls32prevent the rotation plate37from rotating in the return direction, so that the rotation plate37and the output shaft22are held in a locked state. Then, as illustrated inFIGS.23and28, when the rotation of the outer lever41is returned, the remaining pair of pawls32of the four pawls32are also returned to the state of meshing with the internal gear37aof the rotation plate37and the rotation of the rotation plate37in both directions is locked.

As illustrated inFIGS.10and12, the speed increasing unit U includes a substantially disk-shaped planetary carrier62, three planetary gears63, an internal gear23eformed on an outer peripheral portion of the body base23, and the rotation plate37having a sun gear37dat a central portion thereof. As illustrated inFIG.13, the planetary carrier62is integrally assembled with the output shaft22by inserting the output shaft22into a central portion (portion through which the central axis C passes) of the planetary carrier62. The three planetary gears63are rotatably assembled to the planetary carrier62.

The output shaft22integrally assembled with the planetary carrier62is inserted into the central portion (portion through which the central axis C passes) of the rotation plate37, so that the sun gear37dat the central portion of the rotation plate37is gear-coupled to the three planetary gears63to transmit power (seeFIG.14). As illustrated inFIG.13, the coupled three planetary gears63are gear-coupled to the internal gear23eformed on the outer peripheral portion of the body base23to transmit power. Accordingly, when the output shaft22is rotated from the neutral position in either direction, the three planetary gears63revolve while rotating on its own axis along the internal gear23eof the body base23via the planetary carrier62. When the three planetary gears63rotate, the rotation plate37having the sun gear37dgear-coupled to central portions of the planetary gears63is rotated in the same rotation direction as the output shaft22.

At this time, the rotation plate37rotates at an increasing speed according to a gear ratio between gears to rotate at a speed higher than a speed of the output shaft22. In this way, the rotation of the output shaft22is increased in speed by the speed increasing unit U and transmitted to the rotation plate37, so that the rotation plate37can be locked by the lock unit B without causing large backlash in the rotation direction.

As illustrated inFIGS.10and12, the friction generation unit G includes a friction ring57having an opening ring shape and a control piece58having a truncated triangular columnar shape. The control piece58is set between end portions57aof the friction ring57. The friction ring57is fitted to the outer peripheral portion of the disk-shaped rotation plate37. The friction ring57has an opening ring shape slightly smaller than the outer peripheral portion of the rotation plate37in a free state. Here, the rotation plate37corresponds to a “rotation member” of the present disclosure.

As illustrated inFIGS.13and14, the friction ring57is fitted to the outer peripheral portion of the rotation plate37against its elastic force, so that an elastic force that presses the outer peripheral portion of the rotation plate37over substantially the entire circumference from an outer peripheral side is applied to the outer peripheral portion of the rotation plate37. By the pressing described above, the friction ring57applies a sliding friction resistance force to the rotation of the rotation plate37.

The opening ring of the friction ring57is opened by the control piece58, which will be described later, so that a pressed state of the friction ring57against the rotation plate37is released. Accordingly, the friction ring57is released from applying friction to the rotation plate37. Both the end portions57aof the friction ring57are bent obliquely to approach each other in a mountain shape toward a radially outer side.

When the friction ring57applies a friction force to the outer peripheral portion of the rotation plate37as described above, the following effects are achieved. That is, since the rotation of the output shaft22is increased in speed by the speed increasing unit U and transmitted to the rotation plate37, the friction force transmitted from the friction ring57to the rotation plate37is effectively applied. As a result, when the friction ring57is pressed against the rotation plate37(when the output shaft22is rotated downward, which will be described later), it is possible to effectively prevent the output shaft22from slipping in the downward rotation direction.

As illustrated inFIGS.10and12, the control piece58is set between the end portions57aof the friction ring57, and is movable only radially inward and outward relative to the cover24(seeFIG.9). As illustrated inFIG.17, when the outer lever41is in the neutral position, the control piece58is held in a state in which the control piece58is extruded radially outward by the control plate56to be described later. Accordingly, the control piece58enlarges the width between the end portions57aof the friction ring57by both inclined surfaces of the truncated triangular columnar shape, and holds the friction ring57in a state in which the friction ring57is released from being pressed against the rotation plate37.

As illustrated inFIG.24, even when the outer lever41is rotated from the neutral position in a direction (counterclockwise direction in the drawing) in which the output shaft22is rotated upward, the control piece58is held in the state in which the control piece58is extruded radially outward by the control plate56to be described later. Accordingly, the control piece58holds the friction ring57in a state in which the friction ring57is released from being pressed against the rotation plate37, which is a state in which the width between the end portions57aof the friction ring57is enlarged in the same manner as described above.

However, as illustrated inFIG.19, when the outer lever41is rotated from the neutral position in a direction (clockwise direction in the drawing) in which the output shaft22is rotated downward, the control piece58is pulled radially inward by the control plate56to be described later. Accordingly, the control piece58is released from the state in which the width between the end portions57aof the friction ring57is enlarged. As a result, the friction ring57is pressed against the outer peripheral portion of the rotation plate37by the elastic force, and a sliding friction resistance force is applied to the rotation of the rotation plate37.

As illustrated inFIGS.10and12, the rotation control device18further includes the control plate56integrally having a double inner and outer ring plate shape. The control plate56is rotatably supported by the output shaft22with the output shaft22being inserted into a central portion (portion through which the central axis C passes) of the control plate56. The control plate56is integrally assembled with the outer lever41by fitting two arms41cextending from the outer lever41illustrated inFIGS.9and11to an outer peripheral portion of the control plate56.

As illustrated inFIGS.20and25, the control plate56rotates integrally with the outer lever41when the outer lever41is rotated in either direction from the neutral position, and operates to unmesh a corresponding pair of pawls32of the four pawls32from the internal gear37aof the rotation plate37. As illustrated inFIG.24, the control plate56holds the control piece58in a state in which the control piece58is extruded radially outward when the outer lever41is rotated in the direction (counterclockwise direction in the drawing) in which the output shaft22is rotated upward. However, as illustrated inFIG.19, the control plate56is operated to pull the control piece58radially inward when the outer lever41is rotated in the direction (clockwise direction in the drawing) in which the output shaft22is rotated downward.

Accordingly, the friction ring57is pressed against the outer peripheral portion of the rotation plate37by the elastic force, and a sliding friction resistance force is applied to the rotation of the rotation plate37. In this way, since the friction force is applied to the rotation in the direction in which the output shaft22is pushed downward, it is possible to effectively prevent the output shaft22from slipping in the direction in which the output shaft22is pushed downward due to an effect of its own weight applied to the seat1or the like.

As illustrated inFIGS.9and11, the slippage preventing unit D includes the output plate75and a substantially ring plate-shaped plate spring73assembled to the output plate75. A portion of the plate spring73in the circumferential direction is fixed to the output plate75, and another portion of the plate spring73in the circumferential direction can be bent in the axial direction like bending of a cantilever support beam with the fixed portion as a fulcrum.

The plate spring73is assembled to the output plate75in a state in which an elastic force is constantly applied to bend the other portion of the plate spring73to a right side (outer side in the seat width direction). Accordingly, as illustrated inFIGS.17,30, and31, when the outer lever41is in the neutral position, the plate spring73is in a state in which fitting pieces73c, which are formed on a free end side of the plate spring73and protrude to the right side, are fitted into fitting holes24jformed in the cover24by the elastic force.

By the fitting described above, the plate spring73locks the rotation of the output plate75in the clockwise direction (downward rotation direction) illustrated inFIG.17, and allows the rotation of the output plate75in the counterclockwise direction (upward rotation direction). This is because, as illustrated inFIG.31, each of the fitting pieces73cof the plate spring73has an inclined surface73dwhose protrusion decreases in the counterclockwise direction in the drawing.

That is, in a state in which the fitting pieces73care fitted into the fitting holes24jof the cover24, a side surface of each of the fitting pieces73cof the plate spring73straight abuts against a corresponding one of inner side surfaces of the fitting holes24jrelative to the rotation of the output plate75in the clockwise direction (downward rotation direction) in the drawing. However, the inclined surface73dof each of the fitting pieces73cof the plate spring73obliquely abuts against the inner side surface of the corresponding fitting hole24jrelative to the rotation of the output plate75in the counterclockwise direction (upward rotation direction) in the drawing. Therefore, the fitting pieces73cof the plate spring73are pulled out from the fitting holes24jagainst the elastic force accompanying with the rotation of the output plate75by the guiding due to the oblique abutment (refer toFIGS.37and38).

The fitting pieces73cof the plate spring73are pulled out from the fitting holes24jwhen the outer lever41is rotated in the clockwise direction (downward rotation direction) as illustrated inFIG.19from the state in which the outer lever41is in the neutral position illustrated inFIG.17. Accordingly, the rotation lock state of the output plate75in the clockwise direction is released. Specifically, as illustrated inFIG.19, when the outer lever41is rotated in the clockwise direction (downward rotation direction), the rotation transmission plate36is rotated in the clockwise direction.

Accordingly, pressing portions36dformed on the outer peripheral portion of the rotation transmission plate36press pressing pieces73aof the plate spring73to the left side as illustrated inFIG.32. Accordingly, as illustrated inFIG.33, the plate spring73is operated to pull out the fitting pieces73cfrom the fitting holes24jof the cover24against the elastic force. As a result, the output plate75is allowed to rotate in the clockwise direction in the drawing (downward rotation).

As illustrated inFIG.34, when the output shaft22is rotated downward in the clockwise direction in the drawing by the operation of the outer lever41, the plate spring73is disengaged from the pressing portions36das illustrated inFIGS.35and36when slippage of the output shaft22occurs in which the output shaft22rotates preceding to the rotation transmission plate36against the friction force of the friction ring57. Accordingly, the plate spring73causes the fitting pieces73cto fit into the fitting holes24jof the cover24again by its elastic force.

By the fitting described above, the plate spring73locks the rotation of the output plate75in the clockwise direction, and stops the slippage of the output shaft22. Thereafter, when the plate spring73rotates to a position where the rotation transmission plate36catches up with the output shaft22by the operation of the outer lever41, the pressing pieces73aof the plate spring73are pushed leftward by the pressing portions36d, as illustrated inFIGS.19and32. Accordingly, as illustrated inFIG.33, the fitting pieces73cof the plate spring73are pulled out from the fitting holes24jof the cover24, and the downward rotation of the output plate75is allowed.

As illustrated inFIGS.9to12, the rotation control device18further includes torsion springs35,43,71, and55. The torsion spring35is hooked between the outer lever41and the cover24and biases the outer lever41to the neutral position relative to the cover24.

Each of the torsion springs43is hooked between a corresponding pair of upper and lower feed claws52among the four feed claws52, and biases the feed claws52in a rotation direction in which the feed claws52mesh with the internal gear36aof the rotation transmission plate36. The torsion spring71is hooked between the rotation transmission plate36and the output plate75, and holds the output plate75in a state in which the output plate75is biased in the downward rotation direction relative to the rotation transmission plate36and is abutted against the rotation transmission plate36. Each of the torsion springs55is hooked between a corresponding pair of upper and lower pawls32(a pair of upper and front pawls32and a pair of rear and lower pawls32), and biases the pawls32in a rotation direction in which the pawls32mesh with the internal gear37aof the rotation plate37.

{Specific Configurations of Each Unit of Rotation Control Device18}

Next, members constituting the rotation control device18will be described in detail.FIGS.4to8show an assembled state of the rotation control device18.FIGS.9to12are perspective views in which the rotation control device18is disassembled into portions.FIGS.13to16are perspective views in which the rotation control device18is assembled into portions.FIGS.17to38are schematic views illustrating the operation of the rotation control device18for each layer.

Therefore, in the following description, the assembled state of the rotation control device18will be appropriately referred toFIGS.4to8. Configurations of single members will be appropriately referred toFIGS.9to12. Assembled states of the members will be appropriately referred toFIGS.13to16. Operations of the members will be appropriately referred toFIG.17toFIG.38.

First, configurations of the outer lever41and the inner lever53constituting the input unit N will be described. As illustrated inFIGS.9to12and the like, the outer lever41is formed of a substantially disk-shaped member whose surface faces the seat width direction. The outer lever41is integrally assembled with the operation handle5.

The outer lever41is formed with a center hole41ain a central portion (portion through which the central axis C passes). The center hole41apenetrates the central portion in the axial direction in a round hole shape. A fourth columnar shaft portion22g, which constitutes an end portion of the output shaft22on a right side (outer side in the seat width direction), is inserted into the center hole41afrom a left side and is rotatably fitted therein (seeFIGS.7and8). The outer lever41is formed with through holes41bin an intermediate portion of a disk portion in symmetrical positions (upper and lower positions) in the circumferential direction. The through holes41bpenetrate the intermediate portion in the axial direction in a round hole shape.

A pair of stopper pins53bprotruding from the inner lever53to the right side are inserted into the through holes41bfrom the left side and are integrally joined to the through holes41b. Accordingly, the outer lever41is integrally joined to the inner lever53.

The outer lever41is formed with the arms41cat a peripheral edge portion in two positions on a front lower side and a rear upper side. The arms41care bent at a right angle in the axial direction (leftward direction) and overhangs. The arms41cpass through corresponding through holes24gformed in the cover24and are inserted into corresponding insertion grooves56dformed in the outer peripheral portion of the control plate56from the right side to be integrally fitted therein. Accordingly, the outer lever41rotates integrally with the control plate56.

The inner lever53is formed of a substantially disk-shaped member whose surface faces the seat width direction. The inner lever53is formed with a center hole53ain a central portion (portion through which the central axis C passes). The center hole53apenetrates the central portion in the axial direction in a round hole shape. A third columnar shaft portion22f, which constitutes an axially intermediate portion of the output shaft22, is inserted into the center hole53afrom the left side and is rotatably fitted therein (seeFIGS.7and8).

The inner lever53is formed with elongated through holes53cin an intermediate portion of a disk portion in symmetrical positions (upper and lower positions) in the circumferential direction. The through holes53cpenetrate the intermediate portion in the axial direction. The pair of stopper pins53bare inserted into the through holes53cfrom the right side to positions where the stopper pins53babut against the seat, and are integrally joined to the through holes53c. Accordingly, the inner lever53is integrally joined to the outer lever41.

The inner lever53is formed with shaft pins53dat the intermediate portion of the disk portion in four positions in the circumferential direction. The shaft pins53dprotrude in a round pin shape in the axial direction (rightward direction). The four feed claws52are fitted to the shaft pins53dfrom the right side and are rotatably coupled to the shaft pins53d.

Next, configurations of the body base23, the intermediate base25, and the cover24constituting the support unit S will be described with reference toFIGS.9to12and the like. The body base23is formed of a substantially disk-shaped member whose surface faces the seat width direction. The body base23is formed with the internal gear23eat the outer peripheral portion. The internal gear23eis half-punched into a shape that is extruded into a substantially cylindrical shape in the axial direction (rightward direction).

The internal gear23ehas, on its inner peripheral surface, internal teeth formed in an endless shape over the entire circumference. The internal teeth can mesh with the three planetary gears63to transmit power. The body base23is formed with a center hole23cin a central portion (portion through which the central axis C passes) of the internal gear23e. The center hole23cpenetrates the central portion in the axial direction in a round hole shape. The pinion gear22a, which is formed at an end portion of the output shaft22on a left side (inner side in the seat width direction), is inserted into the center hole23cfrom a right side (outer side in the seat width direction). A first columnar shaft portion22b, which constitutes the axially intermediate portion of the output shaft22, is rotatably fitted into the center hole23c(seeFIGS.7and8).

The body base23is formed with a stepped recessed portion23faround the center hole23c. The stepped recessed portion23fconcentrically recesses the periphery of the center hole23cto a left side of an accommodation recessed portion23bthat is a region in the internal gear23e. A disk-shaped flange22h, which constitutes the axially intermediate portion of the output shaft22, is rotatably fitted to the stepped recessed portion23f(seeFIGS.7and8).

By the assembly described above, the axially intermediate portion of the output shaft22, the planetary carrier62assembled to the intermediate portion, and the three planetary gears63are accommodated in the accommodation recessed portion23bthat is a region in the internal gear23eof the body base23(seeFIGS.7,8and13). Specifically, the three planetary gears63are meshed with the internal gear23eof the body base23to transmit power.

A portion of the body base23whose surface faces the axial direction (rightward direction) at protruding tops of the internal gear23eis a seat portion23a. Seat portions24dof the cover24are abutted against the seat portion23ain the axial direction. Locking portions23dare formed in three positions around the seat portion23a. The locking portions23dprotrude in a pedestal shape in the axial direction (rightward direction), and abut against and are integrally bolted (not illustrated) to protruding portions25cin the axial direction. The protruding portions25cprotrude radially outward from corresponding three positions around the intermediate base25.

The intermediate base25and the cover24are overlapped on the seat portion23ain order in the axial direction from the right side (outer side in the seat width direction), and are integrally joined to the seat portion23aby bolting. The body base23is also bolted and integrally joined to the right side frame3a(seeFIG.3).

The body base23is formed with a guide protrusion23gin a lower position on the seat portion23a. The guide protrusion23gprotrudes in the axial direction (rightward direction) to extend straight radially inward and outward in a stripe shape. A slide groove58aformed in the control piece58, which will be described later, is fitted into the guide protrusion23gfrom the right side to be radially slidable. Accordingly, the control piece58is engaged with the guide protrusion23gof the body base23to be movable only radially inward and outward.

The intermediate base25is formed of a substantially ring-shaped member whose surface faces the seat width direction. The intermediate base25is formed with shaft pins25bin four positions in the circumferential direction of a seat portion25ahaving a ring plate shape. The shaft pins25bprotrude in a round pin shape in the axial direction (leftward direction). The four pawls32are fitted into the shaft pins25bfrom the left side and are rotatably coupled to the shaft pins25b.

The intermediate base25is formed with the protruding portions25cin three positions in the circumferential direction of the seat portion25a. The protruding portions25cprotrude radially outward. The protruding portions25care abutted against the corresponding locking portions23dformed in three positions at the seat portion23aof the body base23from the right side, and are bolted and integrally joined to the locking portions23d.

The cover24is formed of a substantially disk-shaped member whose surface faces the seat width direction. The cover24is formed with a flange24hprotruding in a substantially cylindrical shape in the axial direction (leftward direction) from an outer peripheral edge of the cover24. Since the seat portions24d, which are bent at a right angle and extend to an outer peripheral side from the three positions at protruding tops of the flange24h, are abutted against and bolted to the seat portion23aof the body base23, the cover24is integrally coupled to the body base23. By the joining described above, the cover24is set in a state in which components such as the feed unit A and the lock unit B are enclosed between the cover24and the body base23(seeFIGS.4and5).

The cover24is formed with a center hole24ain a central portion (portion through which the central axis C passes) of a disk portion thereof. The center hole24apenetrates the central portion in the axial direction in a round hole shape. The fourth columnar shaft portion22g, which constitutes the end portion of the output shaft22on the right side (outer side in the seat width direction), is inserted into the center hole24afrom the left side and is rotatably fitted therein (seeFIGS.7and8).

The cover24is further formed with two spring hook holes24bin a peripheral edge portion of the disk portion. Each of the spring hook holes24bhas an arc shape penetrating the peripheral edge portion in the axial direction. An operation piece41d, which extends downward from a lower edge portion of the outer lever41, is overlapped between the spring hook holes24bfrom a right side.

End portions of the torsion spring35are inserted into the corresponding two spring hook holes24bfrom the left side. Then, the operation piece41dis sandwiched in the circumferential direction between the end portions of the torsion spring35that are inserted into the spring hooking holes24b. By the assembly described above, the outer lever41is biased to the cover24by the biasing force of the torsion spring35so that the operation piece41dis constantly held in a position between the two spring hook holes24b(neutral position before operation, seeFIG.6).

As illustrated inFIG.10and the like, the cover24is further formed with riding portions24cat the peripheral edge portion of the disk portion. The riding portions24care cut and raised at a right angle and protrude in the axial direction (leftward direction) from symmetrical positions (front and rear positions) in the circumferential direction. As illustrated inFIG.17, each of the riding portions24cis inserted between a corresponding pair of upper and lower feed claws52of the four feed claws52.

As illustrated inFIG.19, when the inner lever53is rotated in a direction (clockwise direction in the drawing) in which the output shaft22is rotated downward, the two feed claws52on a right upper side (front upper side) and a left lower side (rear lower side) of the four feed claws52are abutted against edges of the riding portions24c, and the two feed claws52are unmeshed from the internal gear36aof the rotation transmission plate36. As illustrated inFIG.22, when the rotation of the inner lever53is returned, the riding portions24creturn the two unmeshed feed claws52to the state in which the two feed claws52are meshed with the internal gear36aof the rotation transmission plate36.

Similarly, as illustrated inFIG.24, when the inner lever53is rotated in a direction (counterclockwise direction in the drawing) in which the output shaft22is rotated upward, the two feed claws52on a left upper side (rear upper side) and a right lower side (front lower side) of the four feed claws52are abutted against edges of the riding portions24c, and the two feed claws52are unmeshed from the internal gear36aof the rotation transmission plate36. As illustrated inFIG.27, when the rotation of the inner lever53is returned, the riding portions24creturn the two unmeshed feed claws52to the state in which the two feed claws52are meshed with the internal gear36aof the rotation transmission plate36.

As illustrated inFIG.10and the like, the cover24is formed with guide holes24ein an intermediate portion of the disk portion in symmetrical positions (upper and lower positions) in the circumferential direction. The guide holes24epenetrate the intermediate portion in the axial direction in a shape extending in an arc shape drawn around the central axis C. The stopper pins53b, which extend in the axial direction across the outer lever41and the inner lever53, are inserted into the guide holes24efrom the left side.

Each of the guide holes24ehas a hole shape extending in an arc shape, thereby releasing movement in which the outer lever41and the inner lever53are integrally rotated from the neutral position (seeFIG.29) in the downward rotation direction or in the upward rotation direction. Further, the guide holes24elock the upward and downward movements of the outer lever41and the inner lever53in positions where the stopper pins53babut against end portions of the holes extending in an arc shape.

As illustrated inFIG.9and the like, the cover24is formed with the through holes24gin the peripheral edge portion of the disk portion in two positions on a front lower side and a rear upper side of the cover24. The through holes24gpenetrate the peripheral edge portion in the axial direction in a shape extending in an arc shape drawn around the central axis C. The corresponding arms41cprotruding from the peripheral edge portion of the outer lever41in the axial direction (leftward direction) are inserted into the corresponding through holes24gfrom the right side. Accordingly, the through holes24grelease the movement of the arms41cwhen the outer lever41is rotated from the neutral position.

The cover24is formed with the fitting holes24jin the peripheral edge portion of the disk portion in twelve positions in the circumferential direction. The fitting holes24jpenetrate the peripheral edge portion in the axial direction in a shape extending in a concentric arc shape drawn around the central axis C. The fitting holes24jare holes for locking the movement of the output plate75integrally coupled with the plate spring73and the movement of the output shaft22in the downward rotation direction by fitting the fitting pieces73cof the plate spring73constituting the slippage preventing unit D to the fitting holes24jfrom the left side.

Next, configurations of the four feed claws52, the rotation transmission plate36, and the output plate75constituting the feed unit A will be described with reference toFIG.9,11, and the like. Each of the four feed claws52is formed of an arm-shaped member whose surface faces the seat width direction. Each feed claw52is formed with a center hole52bpenetrating a base end portion of the feed claw52in a round hole shape in the axial direction. Each of the shaft pins53dformed on the inner lever53is fitted into the corresponding center hole52bfrom the right side so that the feed claw52is rotatably coupled to the shaft pin53d.

As illustrated inFIG.17, the four feed claws52are arranged side by side on the inner lever53and constitute pairs in each of the front-rear direction and the upper-lower direction. Among the four feed claws52, each of the two feed claws52on the front upper side and the rear lower side has a shape whose arm extends in the counterclockwise direction in the drawing from a rotation center (shaft pin53d). Each of the two feed claws52on the front lower side and the rear upper side has a shape whose arm extends in the clockwise direction in the drawing from a rotation center (shaft pin53d).

The four feed claws52are formed with external teeth52aat top end portions of the arms thereof. The external teeth52acan mesh with the internal gear36aof the rotation transmission plate36. Each of the torsion springs43is hooked between a corresponding pair of upper and lower feed claws52among the four feed claws52.

The front torsion spring43is set in a state in which one end and the other end thereof are pressed against the front upper feed claw52and the front lower feed claw52, respectively, in a biasing direction in which a resilient force is applied to the front upper feed claw52and the front lower feed claw52. The rear torsion spring43is set in a state in which one end and the other end thereof are pressed against the rear upper feed claw52and the rear lower feed claw52, respectively, in a biasing direction in which a resilient force is applied to the rear upper feed claw52and the rear lower feed claw52.

By assembling the torsion springs43, as illustrated inFIG.17, the feed claws52are constantly pressed and rotated radially outward around corresponding rotation centers (shaft pins53d), and the external teeth52aof the feed claws52are held in a state of being meshed with the internal gear36aof the rotation transmission plate36. Among the four feed claws52, a meshing force applied by the external teeth52ato the internal gear36aof the rotation transmission plate36is different between the pair of two feed claws52on the front upper side and the rear lower side and the pair of two feed claws52on the front lower side and the rear upper side.

Specifically, when the external teeth52aof the two feed claws52on the rear upper side and the front lower side mesh with the internal gear36a, as illustrated inFIG.19, the inner lever53is rotated from the neutral position in the clockwise direction (downward rotation direction) in the drawing, so that the two feed claws52on the rear upper side and the front lower side are integrated with the internal gear36ain the rotation direction to press and rotate the internal gear36ain the clockwise direction. However, after the inner lever53is rotated in the clockwise direction in the drawing, the two feed claws52on the rear upper side and the front lower side are not integrated with the internal gear36arelative to the rotation in the reverse direction in which the inner lever53is returned to the initial position before the operation as illustrated inFIG.22, and are returned to the initial position before the operation while sliding on the internal gear36ain the rotation direction.

On the other hand, as illustrated inFIG.17, when the external teeth52aof the two feed claws52on the front upper side and the rear lower side mesh with the internal gear36a, as illustrated inFIG.24, the inner lever53is rotated from the neutral position in the counterclockwise direction (upward rotation direction) in the drawing, so that the two feed claws52on the front upper side and the rear lower side are integrated with the internal gear36ain the rotation direction to press and rotate the internal gear36ain the counterclockwise direction. However, after the inner lever53is rotated in the counterclockwise direction in the drawing, the two feed claws52on the front upper side and the rear lower side are not integrated with the internal gear36arelative to the rotation in the reverse direction in which the inner lever53is returned to the initial position before the operation as illustrated inFIG.27, and are returned to the initial position before the operation while sliding on the internal gear36ain the rotation direction.

With the above-described configuration, the four feed claws52can feed the rotation transmission plate36in a manner of pressing and rotating the rotation transmission plate36in either rotation direction of the inner lever53from the neutral position. When the inner lever53is returned from the position to which the inner lever53is rotated in either direction to the neutral position, the four feed claws52return the inner lever53to the initial position before the operation while leaving the rotation transmission plate36in the position to which the rotation transmission plate36is pressed and rotated.

As illustrated inFIG.19, when the inner lever53is rotated in the clockwise direction (downward rotation direction) from the neutral position, the two feed claws52on the front upper side and the rear lower side among the four feed claws52are unmeshed from the internal gear36aand held in this state. Further, as illustrated inFIG.24, when the inner lever53is rotated from the neutral position in the counterclockwise direction (upward rotation direction) in the drawing, the two feed claws52on the rear upper side and the front lower side are unmeshed from the internal gear36aand held in this state.

With such a configuration, when the inner lever53is returned from the position to which the inner lever53is rotated in either direction to the neutral position, the two feed claws52that act to restrict the movement of the inner lever53do not hinder the returning movement of the inner lever53. Specifically, as illustrated inFIG.19, when the inner lever53is rotated from the neutral position in the clockwise direction (downward rotation direction) in the drawing, the two feed claws52on the front upper side and the rear lower side are pressed against edges of the corresponding riding portions24cof the cover24, and are rotated to be unmeshed from the internal gear36a. While the inner lever53is operated in the above-described direction, the two feed claws52on the front upper side and the rear lower side ride on the corresponding riding portions24cand are held in a state in which the two feed claws52on the front upper side and the rear lower side are unmeshed from the internal gear36a.

On the other hand, as illustrated inFIG.26, when the inner lever53is rotated from the neutral position in the counterclockwise direction (upward rotation direction) in the drawing, the two feed claws52on the rear upper side and the front lower side are pressed against the edges of the corresponding riding portions24cof the cover24, and are rotated to be unmeshed from the internal gear36a. While the inner lever53is operated in the above-described direction, the two feed claws52on the rear upper side and the front lower side ride on the corresponding riding portions24cand are held in a state in which the two feed claws52on the rear upper side and the front lower side are unmeshed from the internal gear36a.

Here, as illustrated inFIG.17, the external teeth52aof the two feed claws52on the front upper side and the rear lower side mesh with the teeth of the internal gear36ain positions where the external teeth52ashift from the teeth of the internal gear36aby a half pitch. Similarly, the external teeth52aof the two feed claws52on the rear upper side and the front lower side mesh with the teeth of the internal gear36ain positions where the external teeth52ashift from the teeth of the internal gear36aby a half pitch. With such a configuration, the backlash in the rotation direction that may occur between the external teeth52aof the feed claws52and the internal gear36awhen the external teeth52aand the internal gear36amesh with each other is reduced to be small.

When the inner lever53is rotated in the clockwise direction (downward rotation direction) in the drawing, the two feed claws52on the front upper side and the rear lower side press and rotate the internal gear36ain the clockwise direction from the initial stage. However, when the inner lever53is rotated in the counterclockwise direction (upward rotation direction) in the drawing, the two feed claws52on the rear upper side and the front lower side do not apply the force of pressing and rotating the internal gear36ain the counterclockwise direction to the inner gear36aat the initial stage, but press and rotate the inner gear36ain the counterclockwise direction after the rotation progresses to a certain extent.

A reason for this is that the coupling between the rotation transmission plate36and the output plate75, which will be described later, is a coupling in Which, in the initial neutral position, the rotation transmission plate36and the output plate75are released from rotation on one side and the rotation transmission plate36and the output plate75integrally rotate on the other side. That is, as described above with reference toFIGS.17,30, and31, when the inner lever53is in the initial neutral position, the rotation transmission plate36is disposed in a position deviated, relative to the output plate75, in the counterclockwise direction in the drawing from the position where the pressing portions36dpress the pressing pieces73aof the plate spring73by the biasing force of the torsion spring71in order to fit the fitting pieces73cof the plate spring73into the fitting holes24jof the cover24.

Then, as illustrated inFIGS.19,32, and33, initial relative rotation of the rotation transmission plate36relative to the output plate75is allowed in order to press the pressing pieces73aof the plate spring73in the axial direction (leftward direction) with the pressing portions36dand release the lock by the operation of rotating the inner lever53in the clockwise direction (downward rotation direction) from the neutral position. On the other hand, as illustrated inFIGS.24,37, and38, when the inner lever53is rotated from the neutral position in the counterclockwise direction (upward rotation direction) in the drawing, the rotation transmission plate36is integrated with the output plate75in the rotation direction from the initial stage since it is not necessary to release the lock.

As illustrated inFIG.9and the like, the rotation transmission plate36is formed of a substantially disk-shaped member whose surface faces the seat width direction. The rotation transmission plate36is formed with the internal gear36aon the outer peripheral portion. The internal gear36ais half-punched into a shape that is extruded into a substantially cylindrical shape in the axial direction (rightward direction). The rotation transmission plate36is formed with a center hole36bin a central portion (portion through which the central axis C passes) of the disk portion thereof. The center hole36bpenetrates the central portion in the axial direction in a round hole shape.

An external gear-shaped second spline22econstituting the axially intermediate portion of the output shaft22is inserted into the center hole36bfrom the left side to be relatively rotatable. The center hole36bhas a round hole shape slightly larger than a shape of the second spline22eof the output shaft22, and the second spline22eis relatively rotated inside the center hole36b.

The center hole36bis formed with a hooking portion36con an inner circumferential surface in one position in the circumferential direction. The hook portion36cradially protrudes inward. The open ring-shaped torsion spring71is hooked between the hook portion36cand a convex portion of a spline hole75cof the output plate75to be described later. The torsion spring71applies a biasing force to the output plate75so that the output plate75constantly rotates in the clockwise direction in the drawing relative to the rotation transmission plate36.

As illustrated inFIG.9and the like, the rotation transmission plate36is formed with elongated holes36ein three positions in the circumferential direction of the disk portion. The elongated holes36epenetrate the disk portion in the axial direction in a shape extending in an arc shape drawn around the central axis C. The elongated holes36eare arranged side by side and extend in the circumferential direction by the same length in positions of the same circle. Engagement pins75d, which protrude rightward in a round pin shape from three positions in the circumferential direction of the disk portion of the output plate75, are fitted into the corresponding elongated holes36efrom the left side and are engaged with the elongated holes36eto be slidable in the rotation direction.

By the above-described engagement, the rotation transmission plate36and the output plate75are assembled to be rotatable relative to each other in a range in which the engagement pins75dare slidable inside the elongated holes36e. As illustrated inFIG.17, when the inner lever53is in the initial neutral position, the rotation transmission plate36and the output plate75are held in a rotation position in which the engagement pins75dare pressed against end portions of the elongated holes36eon a clockwise side in the drawing by the biasing force of the torsion spring71hooked between the inner lever53and the output plate75.

By the abutment described above, when the rotation transmission plate36is rotated in the clockwise direction (downward rotation direction) inFIG.9by the inner lever53from the neutral position, the rotation transmission plate36is rotated relative to the output plate75to a position where the engagement pins75dare pressed against end portions of the elongated holes36eon a counterclockwise side in the drawing. The rotation transmission plate36rotates in such a manner that the output plate75is integrally pulled in the clockwise direction from a position where the engagement pins75dare pressed against the end portions of the elongated holes36eon the counterclockwise side in the drawing by the rotation.

When the rotation transmission plate36is rotated in the counterclockwise direction (upward rotation direction) inFIG.9by the inner lever53from the neutral position, the engagement pins75dare abutted against the end portions of the elongated holes36eon the clockwise side in the drawing, so that the rotation transmission plate36rotates in such a manner that the output plate75is integrally pulled in the counterclockwise direction from the initial stage.

The rotation transmission plate36is formed with the pressing portions36dat the outer peripheral portion. The pressing portions36dprotrude radially outward from two positions in the circumferential direction of the rotation transmission plate36. As illustrated inFIGS.19and32, when the rotation transmission plate36rotates relative to the output plate75in the clockwise direction (downward rotation direction) in the drawing, the pressing portions36dride on the pressing pieces73aof the plate spring73and press the pressing pieces73ain the axial direction (leftward direction).

As illustrated inFIG.9and the like, the output plate75is formed of a substantially disk-shaped member whose surface faces the seat width direction. The output plate75is formed with a latch portion75ain one position in the circumferential direction of the outer peripheral portion thereof. The latch portion75ais hooked to sandwich a corresponding part of the outer peripheral portion of the plate spring73in the axial direction. The output plate75is further formed with clamping pieces75bin outer peripheral positions that are symmetrical with a position of the latch portion75aof the output plate75in the circumferential direction. The clamping pieces75bextend in a bent shape in the axial direction (rightward direction) and are arranged side by side in two positions in the circumferential direction.

The clamping pieces75bsupport the two claw-shaped fitting pieces73cformed on the plate spring73to be described later in a state in which the two claw-shaped fitting pieces73care collectively clamped from both sides in the circumferential direction. The output plate75can prevent the plate spring73from rotating in the circumferential direction by the hooking by the latch portion75aand the support by the clamping pieces75b, and the formation region of the fitting pieces73ccan be bent in the axial direction like the bending of the cantilever support beam with the latch portion75aas a fulcrum.

The output plate75is formed with the spline hole75cin a central portion (portion through which the central axis C passes) of the disk portion. The spline hole75chas a form of an internal gear penetrating the central portion in the axial direction. The external gear-shaped second spline22e, which constitutes the axially intermediate portion of the output shaft22, is inserted into the spline hole75cin a state of being integrally fitted thereto from the left side. By the fitting described above, the output plate75is coupled to the output shaft22in a state of being integrated with the output shaft22in the rotation direction.

The output plate75is formed with the engagement pins75din three positions in the circumferential direction of the disk portion. The engagement pins75dprotrude rightward in a round pin shape. The engagement pins75dare assembled into the corresponding elongated holes36eformed in the disk portion of the rotation transmission plate36. The description of the specific function will be omitted because it is as described above. A specific configuration of the plate spring73will be described in detail in a detailed description of the slippage preventing unit D to be described later.

Next, configurations of the four pawls32and the rotation plate37constituting the lock unit B will be described with reference toFIGS.10,12, and the like. Each of the four pawls32is formed of an arm-shaped member whose surface faces the seat width direction. Each pawl32is formed with a center hole32bpenetrating a base end portion of the pawl32in a round hole shape in the axial direction. Each of the shaft pins25bformed on the intermediate base25is fitted into the corresponding center hole32bfrom the left side so that the pawl32is rotatably coupled to the shaft pin25b.

As illustrated inFIG.18, the four pawls32are arranged side by side on the intermediate base25and constitute pairs in each of the front-rear direction and the upper-lower direction. Among the four pawls32, each of the two pawls32arranged in the upper-lower direction has a shape whose arm extends in the counterclockwise direction in the drawing from a rotation center (shaft pin25b). Each of the remaining two pawls32arranged in the front-rear direction has a shape whose arm extends in the clockwise direction in the drawing from a rotation center (shaft pin25b).

The four pawls32are formed with external teeth32aat top end portions of the arms thereof. The external teeth32acan mesh with the internal gear37aof the rotation plate37. Each of the torsion springs55is hooked between a corresponding one of the pair of upper and front pawls32and a corresponding one of the pair of lower and rear pawls32among the four pawls32.

The front torsion spring55is set in a state in which one end and the other end thereof are abutted against the upper pawl32and the front pawl32, respectively, in a biasing direction in which a resilient force is applied to the upper pawl32and the front pawl32. The rear torsion spring55is set in a state in which one end and the other end thereof are abutted against the lower pawl32and the rear pawl32, respectively, in a biasing direction in which a resilient force is applied to the lower pawl32and the rear pawl32.

By assembling the torsion springs55, as illustrated inFIG.18, the pawls32are constantly pressed and rotated radially outward around corresponding rotation centers (shaft pins25b), and the external teeth32aof the pawls32are held in a state of being meshed with the internal gear37aof the rotation plate37. Among the four pawls32, a meshing force applied by the external teeth32ato the internal gear37aof the rotation plate37is different between the pair of upper and lower pawls32and the pair of front and rear pawls32.

Specifically, the two upper and lower pawls32prevent the rotation of the rotation plate37in the clockwise direction (downward rotation direction) in the drawing by meshing the external teeth32awith the internal gear37a. However, when the rotation plate37is rotated in the counterclockwise direction (upward rotation direction) in the drawing, even if the external teeth32aof the two upper and lower pawls32mesh with the internal gear37a, as illustrated inFIG.26, the two upper and lower pawls32slide on the internal gear37aand release the rotation of the rotation plate37.

On the other hand, as illustrated inFIG.18, the two front and rear pawls32prevent the rotation of the rotation plate37in the counterclockwise direction (upward rotation direction) in the drawing by meshing the external teeth32awith the internal gear37a. However, when the rotation plate37is rotated in the clockwise direction (downward rotation direction) in the drawing, even if the external teeth32aof the two front and rear pawls32mesh with the internal gear37a, as illustrated inFIG.21, the two front and rear pawls32slide on the internal gear37aand release the rotation of the rotation plate37.

The four pawls32are in the following state when the inner lever53is rotated in the clockwise direction (downward rotation direction) from the neutral position illustrated inFIG.19. That is, as illustrated inFIG.20, the two upper and lower pawls32are unmeshed from the internal gear37aby the control plate56by the rotation and are held in this state. On the other hand, the two front and rear pawls32are held in a state of being meshed with the internal gear37a. Accordingly, the four pawls32are brought into a state in which the rotation of the rotation plate37in the clockwise direction (downward rotation direction) in the drawing can be released (seeFIG.21).

When the operation of the inner lever53is returned to the neutral position as illustrated inFIG.22after the rotation plate37is rotated in the clockwise direction in the drawing, the two front and rear pawls32meshing with the internal gear37aamong the four pawls32prevent the rotation of the rotation plate37in the counterclockwise direction in the drawing and hold the rotation plate37in the fixed position as illustrated inFIG.23. When the operation of the inner lever53(seeFIG.22) is returned to the neutral position, the rotation of the control plate56is returned to the initial position. Accordingly, as illustrated inFIG.23, the two upper and lower pawls32are returned to the initial state of meshing with the internal gear37a.

On the other hand, the four pawls32are in the following state when the inner lever53is rotated in the counterclockwise direction (upward rotation direction) from the neutral position illustrated inFIG.24. That is, as illustrated inFIG.25, the two front and rear pawls32are unmeshed from the internal gear37aby the control plate56by the rotation and are held in this state. On the other hand, the two upper and lower pawls32are held in a state of being meshed with the internal gear37a. Accordingly, the four pawls32are brought into a state in which the rotation of the rotation plate37in the counterclockwise direction (upward rotation direction) in the drawing can be released (seeFIG.26).

When the operation of the inner lever53is returned to the neutral position as illustrated inFIG.27after the rotation plate37is rotated in the counterclockwise direction in the drawing, the two upper and lower two pawls32meshing with the internal gear37aamong the four pawls32prevent the rotation of the rotation plate37in the clockwise direction in the drawing and hold the rotation plate37in the fixed position as illustrated inFIG.28. When the operation of the inner lever53(seeFIG.27) is returned to the neutral position, the rotation of the control plate56is returned to the initial position. Accordingly, as illustrated inFIG.28, the two front and rear pawls32are returned to the initial state of meshing with the internal gear37a.

As illustrated inFIGS.10,12, and the like, the rotation plate37is formed of a substantially disk-shaped member whose surface faces the seat width direction. The rotation plate37is formed with the internal gear37aat an outer peripheral portion. The internal gear37ais half-punched into a shape that is extruded into a substantially cylindrical shape in the axial direction (rightward direction). The internal gear37ais formed with, on its inner circumferential surface, internal teeth in an endless shape over the entire circumference. The internal teeth can mesh with the external teeth32aof the four pawls32.

The rotation plate37is further formed with a center hole37cin a central portion (portion through which the central axis C passes) of the disk portion37b. The center hole37cpenetrates the central portion in the axial direction in a round hole shape. A cylindrical second shaft portion22d, which constitutes the axially intermediate portion of the output shaft22, is rotatably fitted into the center hole37c(seeFIGS.7and8).

The sun gear37dprotruding in the axial direction (leftward direction) is formed around the center hole37cof the rotation plate37. When the output shaft22is set in the center hole37cof the sun gear37d, the sun gear37dis set among the three planetary gears63of the planetary carrier62assembled to the intermediate portion of the output shaft22, and is gear-coupled to the planetary gears63to transmit power.

Accordingly, w % ben the three planetary gears63are rotated accompanying the rotation of the output shaft22, the sun gear37dreceives the transmission of the rotational driving force and rotates. Specifically, the sun gear37drotates by increasing the speed at which the three planetary gears63rotate in the internal gear23eof the body base23by the gear ratio of the meshing.

Next, configurations of the planetary carrier62and the three planetary gears63constituting the speed increasing unit U will be described with reference toFIGS.10,12, and the like. The specific configuration and function of the rotation plate37constituting the speed increasing unit U are as described above.

The planetary carrier62is formed of a substantially ring-shaped member whose surface faces the seat width direction. The planetary carrier62is formed with a spline hole62ain a central portion (portion through which the central axis C passes). The spline hole62ahas a form of an internal gear and penetrates the central portion in the axial direction.

An external gear-shaped first spline22c, which constitutes the axially intermediate portion of the output shaft22, is inserted into the spline hole62afrom the left side and is integrally fitted to the spline hole62ain the rotation direction. By the fitting described above, the planetary carrier62is coupled to the output shaft22in a state of being integrated with the output shaft22in the rotation direction.

The planetary carrier62is formed with shaft pins62bin three positions in the circumferential direction on the ring plate. The shaft pins62bprotrude in a round pin shape in the axial direction (rightward direction). The three planetary gears63are fitted into the corresponding shaft pins62bfrom the right side and are rotatably coupled to the shaft pins62b.

Each of the three planetary gears63is a substantially disk-shaped external gear whose surface faces the seat width direction. Each of the three planetary gears63is formed with a center hole63apenetrating a central portion of the planetary gear63in a round hole shape in the axial direction. Each of the shaft pins62bof the planetary carrier62is fitted into the corresponding center hole63afrom the right side so that the three planetary gears63are rotatably coupled to the shaft pins62b.

The planetary gears63are set in a state of being meshed with the internal gear23eof the body base23by being assembled to the body base23via the planetary carrier62and the output shaft22(seeFIG.13and the like). As a result of the assembly described above, when the output shaft22is rotated in either direction, the planetary gears63revolve while rotating on its own axis in the corresponding rotation direction along the internal gear23eof the body base23.

Next, configurations of the friction ring57and the control piece58constituting the friction generation unit G will be described with reference toFIGS.10,12, and the like. The friction ring57is formed of an opened ring member. The friction ring57is fitted to the outer peripheral portion of the rotation plate37. Both the end portions57aof the friction ring57are bent obliquely to approach each other in a mountain shape toward the radially outer side.

The control piece58is formed of a substantially truncated triangular columnar shaped member fitted between the end portions57aof the friction ring57. The control piece58is sandwiched between the end portions57aof the friction ring57. The control piece58is set in a state in which the slide groove58a, which is formed in a left side surface of the control piece58and recessed in a shape extending in a stripe shape in the radial direction, is fitted to the guide protrusion23gformed on the body base23from the right side.

Further, as illustrated inFIG.10and the like, the control piece58is set in a state in which a round pin-shaped engagement pin58b, which protrudes from a right side surface of the control piece58, is inserted from the left side into a riding hole56hformed along the outer peripheral portion of the control plate56. The riding hole56hhas a shape extending in an arc shape drawn around the central axis C of the control plate56. The riding hole56hcommunicates with a relief hole56gvia an inclined joint at an end portion of the riding hole56hon a counterclockwise side illustrated inFIG.10. The riding hole56hhas a slightly small diameter and extends in a concentric arc shape in the counterclockwise direction in the drawing.

As illustrated inFIG.17, when the outer lever41integrally formed with the control plate56is in the neutral position, the engagement pin58bof the control piece58is located at the end portion of the riding hole56hof the control plate56on the counterclockwise side in the drawing. In this state, the control piece58is extruded radially outward relative to the body base23, the width between both the end portions57aof the friction ring57is enlarged by both inclined surfaces of the truncated triangular columnar shape, so that the state in which the friction ring57is pressed against the rotation plate37is released.

As illustrated inFIG.19, when the outer lever41is rotated in the clockwise direction (downward rotation direction) from the neutral position, the engagement pin58bof the control piece58is pulled into the relief hole56gfrom the riding hole56hof the control plate56, and is pulled radially inward relative to the body base23. Accordingly, the control piece58releases the state in which the width between the end portions57aof the friction ring57is enlarged. As a result, the friction ring57is pressed against the outer peripheral portion of the rotation plate37by the elastic force, and a sliding friction resistance force is applied to the rotation of the rotation plate37.

Specifically, in the control piece58, the engagement pin58bis pulled into the relief hole56gof the control plate56before the outer lever41is rotated in the clockwise direction (downward rotation direction) in the drawing and the two pawls32are unmeshed from the internal gear37aof the rotation plate37as illustrated inFIG.20. Then, when the outer lever41is further rotated in the clockwise direction (downward rotation direction) in the drawing, the two pawls32are unmeshed from the internal gear37aof the rotation plate37.

With such a configuration, it is possible to unlock the output shaft22after a friction force is applied to the output shaft22that receives the weight of the seat1, and to release the lock quietly in a state in which the weight of the seat1is less likely to be applied. After the lock is released, the output shaft22can be rotated in a direction (clockwise direction in the drawing) in which the output shaft22is smoothly rotated downward while maintaining a state in which a friction force is applied to the output shaft22.

On the other hand, as illustrated inFIG.24, when the outer lever41is rotated in the counterclockwise direction (upward rotation direction) from the neutral position, the engagement pin58bof the control piece58slides in the riding hole56hof the control plate56. For this reason, the control piece58is held in a state of being extruded radially outward relative to the body base23and the friction ring57is released from being pressed against the rotation plate37. Therefore, when the outer lever41is rotated in the counterclockwise direction (upward rotation direction) from the neutral position, no friction force is applied from the friction ring57to the rotation plate37.

Next, the configuration of the control plate56will be described with reference toFIGS.9to12and the like. The control plate56integrally has a double inner and outer ring plate shape whose surface faces the seat width direction. In the control plate56, a ring plate on an inner peripheral side and a ring plate on an outer peripheral side are coupled in two positions in the circumferential direction by coupling portions56c. The control plate56has a shape in which the ring plate on the inner peripheral side is shifted to the left side relative to the ring plate on the outer peripheral side via the coupling portions56c.

The control plate56is formed with a center hole56ain a central portion (portion through which the central axis C passes). The center hole56apenetrates the central portion in the axial direction in a round hole shape. The cylindrical second shaft portion22d, which constitutes the axially intermediate portion of the output shaft22, is rotatably fitted into the center hole56a(seeFIGS.7and8).

The control plate56is formed with the insertion grooves56din an outer peripheral portion of the ring plate on the outer peripheral side in two positions in the circumferential direction. The insertion grooves56dare recessed radially inward. The arms41cextending leftward from the outer lever41are fitted into the corresponding insertion grooves56dfrom the right side. Accordingly, the control plate56is coupled to the outer lever41in a state of being integrated with the outer lever41in the rotation direction (seeFIG.18).

The control plate56is formed with hooking portions56bat an outer peripheral portion of the ring plate on the inner peripheral side in four positions in the circumferential direction. The hooking portions56bbulge radially outward in a claw shape. As illustrated inFIGS.20and25, when the control plate56is rotated in either direction, the hooking portions56bare pressed against corresponding claw portions formed on inner peripheral portions of the four pawls32, and are operated to unmesh the claw portions from the internal gear37aof the rotation plate37.

As illustrated inFIG.10and the like, the riding hole56hand the relief hole56gare formed in the outer peripheral portion of the ring plate on the outer peripheral side of the control plate56. Specific configurations and functions of the riding hole56hand the relief hole56gare as described above.

As illustrated inFIGS.10,12, and the like, the output shaft22includes the pinion gear22a, the first shaft portion22b, the flange22h, the first spline22c, the second shaft portion22d, the second spline22e, the third shaft portion22f, and the fourth shaft portion22garranged side by side on the same axis from the left side. The coupling of the portions of the output shaft22to other members is as described above. The output shaft22has a both-end support structure in which the second shaft portion22dis fitted into the center hole23cof the body base23to be rotatably supported, and the fourth shaft portion22gis fitted into the center hole24aof the cover24to be rotatably supported.

Next, a configuration of the plate spring73constituting the slippage preventing unit D will be described with reference toFIGS.9to12and the like. The specific configuration and function of the output plate75constituting the slippage preventing unit D are as described above.

As illustrated inFIG.9and the like, the plate spring73is formed of a substantially ring-shaped member whose surface faces the seat width direction. The plate spring73is formed with the pressing pieces73ain two positions in the circumferential direction at the outer peripheral portion of the ring plate. The pressing pieces73aare bent at a right angle and protrude in the axial direction (rightward direction). Each of the pressing pieces73ahas an inclined surface73bon an end surface of a protruding top (seeFIG.30). The inclined surface73bis inclined to reduce the protrusion in the counterclockwise direction in the drawing.

The plate spring73is further formed with the fitting pieces73cin positions that are symmetrical in the circumferential direction with the position where the plate spring73is hooked by the latch portion75aof the output plate75. The fitting pieces73care bent at a right angle and protrude in the axial direction (rightward direction) from the inner peripheral edge and are arranged side by side in two positions in the circumferential direction. The fitting pieces73care spaced apart from each other in the circumferential direction. Each of the fitting pieces73chas the inclined surface73don an end surface of a protruding top (seeFIG.31). The inclined surface73dis inclined to reduce the protrusion in the counterclockwise direction in the drawing.

The plate spring73is further formed with pressing portions73ein two positions in the circumferential direction in which an inner peripheral portion in the position where the plate spring73is hooked by the latch portion75aof the output plate75is sandwiched. The pressing portions73eextend opposite to each other in a cantilever shape in the circumferential direction. Each of the pressing portions73ehas a shape in which an extending intermediate portion is bent leftward in a crank shape. Each of the pressing portions73ehas an end portion on its extending top pressed against a right side surface of the outer peripheral portion of the output plate75.

By the above-described assembly, an elastic force for pressing the plate spring73rightward is applied to the plate spring73with the pressing portions73epressed against the output plate75as a fulcrum. As illustrated inFIG.17, when the inner lever53is in the initial neutral position, the plate spring73is held in a state in which the pressing pieces73aand the fitting pieces73cprotrude rightward with the position where the plate spring73is hooked by the latch portion75aas a fulcrum (seeFIGS.30and31).

By the protrusion described above, as illustrated inFIG.31, the fitting pieces73cof the plate spring73are fitted into the corresponding fitting holes24jof the cover24. Accordingly, the plate spring73locks the movement of the output plate75and the output shaft22, which are integrally coupled to the plate spring73, in the downward rotation direction (the left direction in the drawing). However, since the inclined surface73dof each of the fitting pieces73cabuts against the inner peripheral surface of the corresponding fitting hole24j, the plate spring73allows the movement of the output plate75and the output shaft22in the upward rotation direction (right direction in the drawing). The operation of allowing this movement will be described later.

The plate spring73releases the lock state when the outer lever41is rotated in the clockwise direction (downward rotation direction) as illustrated inFIG.19from the neutral position illustrated inFIG.17and the rotation transmission plate36is rotated in the clockwise direction as illustrated inFIG.19. Specifically, by the rotation of the rotation transmission plate36, the pressing portions36dformed on the rotation transmission plate36ride on the pressing pieces73aof the plate spring73and press the pressing pieces73aleftward (seeFIG.32).

Specifically, the pressing portions36dof the rotation transmission plate36slide on the inclined surfaces73bof the pressing pieces73aof the plate spring73and ride on right end surfaces of the pressing pieces73a. When the pressing pieces73aare pressed leftward by the above-described riding, the plate spring73pulls the fitting pieces73cleftward from the corresponding fitting holes24jof the cover24(seeFIG.33). Accordingly, the lock state of the output plate75and the output shaft22in the downward rotation direction (leftward direction in the drawing) is released.

The unlocking of the plate spring73described above is performed preceding to the unlocking of the pawls32accompanying the rotation of the outer lever41in the downward rotation direction. With such a configuration, it is possible to appropriately prevent an excessive load from being applied to fitting portions between the fitting pieces73cof the plate spring73and the fitting holes24jof the cover24due to the preceding release of the pawls32.

Then, by the downward rotation of the outer lever41after the above-described unlocking of the plate spring73is performed, the end portions of the elongated holes36eof the rotation transmission plate36described with reference toFIG.9and the like abut against the corresponding engagement pins75dof the output plate75. Accordingly, the output plate75rotates integrally with the rotation transmission plate36in the downward rotation direction.

When an excessive load is applied to the seat cushion3from above during the downward rotation, an excessive load in the downward rotation direction exceeding the friction force of the friction ring57may be applied to the output shaft22. When such an excessive load is applied to the output shaft22, as illustrated inFIG.34, the output plate75integrated with the output shaft22may slip to rotate in the downward rotation direction preceding to the rotation transmission plate36.

However, when such slippage occurs, the fitting pieces73cof the plate spring73are released from being pressed by the pressing portions36dof the rotation transmission plate36accompanying the preceding rotation of the output plate75(seeFIG.35). Accordingly, as illustrated inFIG.36, the fitting pieces73cof the plate spring73are fitted into the corresponding fitting holes24jof the cover24again by the elastic force. By the fitting described above, the movement of the output plate75and the output shaft22in the downward rotation direction is locked. Therefore, the slippage of the output shaft22when the excessive load is input can be prevented at an early stage.

On the other hand, when the outer lever41is rotated in the counterclockwise direction (upward rotation direction) as illustrated inFIG.24from the neutral position illustrated inFIG.17and the rotation transmission plate36is rotated in the counterclockwise direction, the plate spring73allows the rotation in the counterclockwise direction. Specifically, in response to the rotation in the counterclockwise direction, the output plate75rotates integrally with the rotation transmission plate36(seeFIG.37). Accordingly, as illustrated inFIG.38, the plate spring73that rotates integrally with the output plate75rotates the fitting pieces73cfitted into the fitting holes24jof the cover24in the counterclockwise direction (rightward direction in the drawing).

By the rotation described above, the fitting pieces73cof the plate spring73press the inclined surfaces73dagainst inner peripheral surfaces of the fitting holes24jin the rotation direction (rightward direction in the drawing). Accordingly, the fitting pieces73cof the plate spring73are pressed leftward against the elastic force by the counterforce caused by the abutment between the inclined surfaces73dand the inner peripheral surfaces of the fitting holes24j, and are released leftward from the fitting holes24j. With the progress of the above-described movement, the plate spring73allows the output plate75and the output shaft22to move in the upward rotation direction.

Summary

In summary, the seat lifter device10according to the first embodiment has the following configuration. In the following description, reference numerals in parentheses correspond to respective configurations described in the above-described embodiment.

That is, a seat lifter device (10) includes an output shaft (22) configured to raise and lower a seat (1) in accordance with a rotational operation amount of an operation handle (5). The seat lifter device (10) includes a support unit (S) that supports the output shaft (22) such that the output shaft (22) is rotatable, and an input unit (N) rotatably coupled to the support unit (S) and integrally coupled to the operation handle (5). The seat lifter device (10) further includes a feed unit (A) that transmits rotation of the input unit (N) to the output shaft (22), and a lock unit (B) that locks rotation of the output shaft (22) relative to the support unit (S). The seat lifter device (10) further includes a friction generation unit (G) provided between the support unit (S) and a rotation member (37) configured to rotate together with the output shaft (22), and a slippage preventing unit (D) provided in a power transmission path between the output shaft (22) and the feed unit (A).

The feed unit (A) is of a ratchet type, transmits bidirectional rotation of the input unit (N) from a neutral position to the output shaft (22), and does not transmit rotation of the input unit (N) returning to the neutral position to the output shaft (22). The lock unit (B) unlocks the output shaft (22) in response to an operation of the input unit (N) rotating from the neutral position, and locks the rotation of the output shaft (22) in response to an operation of the input unit (N) returning to the neutral position.

The friction generation unit (G) applies a friction force between the rotation member (37) and the support unit (S) in response to the operation of the input unit (N) rotating in a direction in which the seat (1) is lowered, thereby stopping preceding rotation of the output shaft (22) due to a weight of the seat (1). The slippage preventing unit (D) transmits rotation of the feed unit (A) to the output shaft (22) by the operation of the input unit (N) rotating from the neutral position. When the input unit (N) rotates in the direction in which the seat (1) is lowered and the output shaft (22) rotates preceding to the feed unit (A) against the friction force of the friction generation unit (G) to slip, the slippage preventing unit (D) is fitted to the support unit (S) by an elastic force in response to the slippage of the output shaft (22) to stop the slippage.

According to the above-described configuration, when the input unit (N) is rotated in the direction in which the seat (1) is lowered, the lock unit (B) is unlocked and the output shaft (22) is fed in a rotation direction in which the seat (1) is lowered via the feed unit (A). At this time, the output shaft (22) is prevented from slipping due to the weight of the seat (1) by the friction generation unit (G). Even when an excessive load in a downward rotation direction that exceeds the friction force of the friction generation unit (G) is input to the output shaft (22) from an output side, the slippage preventing unit (D) is fitted to the support unit (S) so that a slip rotation is prevented. Therefore, it is possible to appropriately stop the slippage of the seat (1) when the seat (1) is lowered.

The slippage preventing unit (D) is fitted to the support unit (S) in an axial direction. According to the above-described configuration, the slippage preventing unit (D) can be configured in a relatively space-saving manner.

In response to the operation of the feed unit (A) rotating to a position in which the slippage of the output shaft (22) does not occur by the rotation of the input unit (N), the slippage preventing unit (D) in a state of being fitted to the support unit (S) is released from the state of being fitted to the support unit (S) against the elastic force. According to the above-described configuration, even after the slippage preventing unit (D) is fitted to the support unit (S), the slippage preventing unit (D) can be returned to a state in which the slippage preventing unit (D) can function again by the feed unit (A) rotating to the position in which the slippage does not occur.

The slippage preventing unit (D) is fitted to the support unit (S) by the elastic force even when the input unit (N) is in the neutral position. The slippage preventing unit (D) is released from the state of being fitted to the support unit (S) against the elastic force when the input unit (N) rotates in the direction in which the seat (1) is lowered, thereby allowing the output shaft (22) to rotate. The slippage preventing unit (D) has an inclined surface (73d), and is released from the state of being fitted to the support unit (S) against the elastic force by the inclined surface (73d) being abutted against the support unit (S) when the input unit (N) rotates in a direction in which the seat (1) is raised, thereby allowing the output shaft (22) to rotate.

According to the above-described configuration, it is possible to prevent the output shaft (22) from slipping even when the input unit (N) is in the neutral position. Even with such a configuration, the slippage preventing unit (D) can avoid hindering the input unit (N) from rotating in the direction in which the seat (1) is raised.

The slippage preventing unit (D) is released from the state of being fitted to the support unit (S) before the lock unit (B) unlocks the output shaft (22) when the input unit (N) rotates from the neutral position in the direction in which the seat (1) is lowered. According to the above-described configuration, the lock unit (B) can be prevented from being released first and an excessive load can be prevented from being applied to the slippage preventing unit (D).

Other Embodiments

Although embodiments of the present disclosure have been described above using one embodiment, the present disclosure can be implemented in various forms described below in addition to the above-described embodiment.

1. The seat lifter device of the present disclosure can be widely applied not only to a seat mounted on a vehicle other than an automobile, such as a railway, but also to a seat mounted on a vehicle other than a vehicle, such as an aircraft or a ship. The seat lifter device can be widely applied to non-vehicle seats such as grandstands and massage seats installed in various facilities such as sports facilities, theaters, concert venues, and event venues.

2. The friction generation unit may weaken the pressure applied to the rotation member instead of releasing the pressure when the input unit is in the neutral position and when the input unit rotates in a direction to raise the seat. One of the portion of the friction generation unit that is pressed against the rotation member and the portion of the rotation member that is pressed by the friction generation unit may have a square shape or another irregular shape instead of a circular shape.

The friction generation unit may be pressed against the rotation member from a plurality of positions (for example, two positions, three positions, or four positions) in the rotation direction individually, in addition to being pressed against the rotation member from the outer peripheral side in a surrounding manner. The friction generation unit may be pressed against the rotation member in a thrust direction to generate a friction force, in addition to from the inner peripheral side to generate a friction force. The rotation member to which the friction generation unit applies the friction force may be a member (“rotation transmission plate36” or “output plate75” described in the first embodiment) that rotates integrally with the output shaft, in addition to a member (“rotation plate37” described in the first embodiment) of which the rotation speed is increased via the speed increasing unit.

3. The slippage preventing unit may be fitted to the support unit in a radial direction. The slippage preventing unit may be not fitted to the support unit in a state where the input unit is in the neutral position. When the input unit is rotated from the neutral position in the direction in which the seat is lowered, either of the slippage preventing unit and the lock unit may be first unlocked, or the lock unit may be first unlocked.