JPH0995165A - Longitudinal tilt mechanism for seat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with operation of a seat cushion on the side. SOLUTION: Worms 42, 44 meshing with the worm wheels 38, 40 of front and rear brake means 32, 34 are respectively rotatably arranged on the same axis. A drive shaft 54 having a knob 52 extended on the front part of a seat cushion 11 is formed so as to integratedly have engaging pieces 56, 58 capable of being engaged with the engaging parts 48 of the worms, arranged to be continuously inserted through the inserting through holes 50 of the respective worms, and rotatably supported, so that it can be moved in the axial direction between the drawn out position and the pushed-in position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat back-and-forth tilt mechanism that allows the seat cushion to be tilted back and forth by individually adjusting the front and back heights of the seat cushion by a predetermined operation of an operating member.

[0002]

2. Description of the Related Art For example, an anteroposterior tilt mechanism is provided for an automobile or the like in which the front and rear heights of a seat cushion can be individually adjusted to arbitrarily set the inclination angle of the seat cushion according to the occupant's body shape, preference, and the like. Is attached to the seat.

Such a front-rear tilt mechanism is also called a height device or the like, and the structure thereof is, for example, Jikken 06-035771.
It is disclosed in Japanese Patent Publication No. In this type of front-rear tilt mechanism (height device), for example, the seat cushion is individually supported in the front-rear direction by front and rear links, and the rotation of each link is regulated by corresponding front and rear braking means and a knob. The front and rear heights of the seat cushion can be individually adjusted by rotating the corresponding links by means such as.

[0004]

By the way, the above-mentioned actual fairness
As disclosed in Japanese Patent Laid-Open No. 06-035771, in a known front-rear tilt mechanism, a torque shaft, which is a center of rotation of a front and rear link, is arranged in the front-rear direction of a seat cushion and extends in the left-right direction. Since the support shaft of the brake means that can be interlocked with the shaft is arranged along the torque shaft, the operation member that rotates the torque shaft, that is, the front and rear links via the support shaft of the brake means is usually , Are extended and arranged on the corresponding left and right sides of the seat.

However, since a seat of an automobile or the like is usually arranged in a limited narrow space, a space for arranging operation members and an operation space by a seated person's hand are not always ensured on the left and right sides of the seat cushion. Not always possible. That is, in a seat where a predetermined space cannot be secured on the left and right sides, the front-rear tilt mechanism cannot be easily mounted, so that the use range of the front-rear tilt mechanism cannot be avoided in an automobile or the like.

An object of the present invention is to provide a seat back-and-forth tilt mechanism that does not require lateral operation of the seat cushion.

[0007]

To achieve this object, according to the present invention, front and rear braking means having a worm wheel on the input side of the support shaft are juxtaposed at corresponding positions on the same side of the seat. Has been done. And
A worm that meshes with the worm wheel is formed with a non-circular detent-shaped engaging portion in the insertion hole at the center of rotation, and is rotatably arranged on the front and rear sides coaxially. .

Further, the drive shaft having an operating member extending to the front portion of the seat cushion is integrally formed with engaging pieces capable of engaging with the engaging portions of the front and rear worms. The worms are continuously inserted through the insertion holes of the worms and axially supported so as to be movable in the axial direction between the pull-out position and the push-in position. Then, by engaging or depressing the drive shaft in the axial direction, the engaging piece of the drive shaft is engaged with the engaging portion of either the front or the rear worm, and the operation member is used to pull out or push the worm. The front and rear links can be individually rotated by rotating the drive shaft.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIGS. 1 and 2, a seat front / rear tilt mechanism 10 according to the present invention includes a pair of left and right front and rear links 12 and 14 for individually supporting the front and rear portions of a seat cushion 11. (FIG. 2 shows only one side).

For example, a pair of left and right side brackets 16
Is placed on the upper rail 20 of the seat slide device 18,
Corresponding links 12 and 14 are arranged on front and rear torque shafts 22 and 24 that are fixed and are erected and erected between the left and right side brackets, respectively.

The seat slide device 18 is composed of, for example, an upper rail 20 and a lower rail 26 fixed to a vehicle floor or the like, and the upper rail is slidable with respect to the lower rail so that a steel ball, a roller or the like can be rolled. It is assembled via a pendulum (not shown). The structure of the seat slide device 18 is well known, and the structure itself is not the subject of the present invention, and therefore will not be described in detail here.

As can be seen from FIGS. 1 and 2, the front and rear torque shafts 22 and 24 are formed, for example, with an integrally rotatable sector gear 28. Corresponding mating pinion 30
Via the combination with and, the front and rear corresponding braking means 32, 34 are connected to the output side of the support shaft 36 respectively so as to be interlockable.

The front and rear braking means 32, 34 are
The output side of the support shaft 36 is extended inward of the seat, and is fixed to the same side of the seat, that is, the same side bracket 16, and the engagement of the sector gear 28 and the pinion 30 on the inner side of the seat causes each of the braking means to move. The support shafts correspond to the corresponding torque shafts 22, 24, that is, the front and rear links 12, 14
It is linked so that it can be linked to.

The braking means 32, 34 are constructed so that the rotation of the support shaft 36 in one direction can be restricted by a built-in restraining member (not shown). However, the principle, configuration, etc.
As disclosed in Japanese Utility Model Laid-Open No. 05-040028, etc., it is general, and the configuration itself is not the gist of the present invention, so a detailed description of the braking means 32, 34 will be omitted.

The front and rear braking means 32, 3
4 is the downward link 1 due to the effect of the load from the seated person
It is configured to restrict the rotation of 2 and 14 respectively.

As shown in FIGS. 1 and 2, in the seat front-rear tilt mechanism 10 of the present invention, the worm wheels 38, 40 have front and rear braking means 32, 34 on the input side of the support shaft 36. The worms 42 and 44 which are respectively provided on the front side and the rear side are coaxially rotatably arranged and supported by the bracket 46 on the front and rear sides, respectively.

The worms 42, 44 are formed with a non-circular detent shaped engaging portion 48 in the insertion hole 50 at the center of rotation. As can be seen from FIG. 1, in the embodiment of the present invention, the engaging portions 48 are partially provided on the opposite sides of the front and rear worms 42 and 44.

As shown in FIGS. 1 and 2, the drive shaft 54 integrally having the operation member 52 extending forward of the seat cushion 11 at the front end is provided with the front and rear worms 42, 44. Are continuously inserted through the insertion holes 50 and are axially supported. Drive shaft 54 has 4 worms, front and rear
It is formed integrally with engaging pieces 56, 58 which can engage with the engaging portions 48 of 2, 44 at corresponding locations, and is formed under the engagement between the engaging portions and engaging pieces. In the present invention, the worm that rotates is integrally rotated.

As the operating member 52, for example, a rotating operation,
In addition, a substantially circular knob that can be easily pulled out and pushed in as described later can be used.

In the embodiment of the present invention,
The worm engagement portion 48 and the drive shaft engagement pieces 56, 58 are each formed as corresponding serrations that are engageable with each other.

The drive shaft 54 is formed, for example, by a combination of the engaging pieces 56, 58 and the connecting shafts 60, 62. , A locking member 64 consisting of a spring pin, etc.
Are connected integrally.

As can be seen from FIG. 3 in addition to FIG. 1, in the present invention, the drive shaft 54 is supported so as to be movable in the axial direction, and is driven by the pull-out operation and push-in operation of the knob 52. By the movement of the shaft, the engagement pieces 56, 58 of the drive shaft
Any of the above is configured to be engageable with the corresponding engaging portions 48 of the front and rear worms 42, 44. For example,
In the pulled-out position of the drive shaft 54 shown in FIG. 1, the engagement piece 56 engages with the engagement portion 48 of the worm 42 on the front side to enable the worm to rotate in conjunction with the drive shaft. At the push-in position of the drive shaft shown in the drawing, the engagement piece 58 engages with the engagement portion of the rear worm 44 so that the worm can rotate in conjunction with the drive shaft.

With such a structure, when the knob 52, that is, the drive shaft is rotated when the engaging piece 56 is engaged with the engaging portion 48 when the drive shaft 54 is pulled out as shown in FIG.
The rotation of the worm wheel 38 accompanying the rotation of the worm wheel 38 causes the support shaft 36 of the braking means 32 to rotate in the corresponding direction together with the pinion 30 on the output side, which causes the sector gear 28 and the torque shaft 22 to rotate.
The front portion of the seat cushion 11 is moved up and down with respect to the rear portion by the rotation of the front link 12 via the.

As can be seen from FIG. 1, the drive shaft
At the pull-out position of 54, the rear engaging portion 48 and the engaging piece
Since the parts between the 58 are in the disengaged position, even if the drive shaft 54 is rotated under the operation of the knob 52, the rotational force thereof is the worm of the rear.
Not transmitted to 44. That is, when the drive shaft 54 is pulled out, only the front link 12 is rotatable, so that the front portion of the seat cushion 11 is moved up and down with respect to the rear portion.

On the contrary, when the drive shaft 54 is pushed in as shown in FIG. 3, the rear engagement piece 58 engages with the engagement portion 48 of the worm 44, so that the knob 52 in this state is engaged. If the drive shaft is rotated under the operation of, the rotation of the worm wheel 40 associated with the worm, that is, the support shaft 3 of the braking means 34.
6. By rotating the rear link 14 via the torque shaft 22, the rear portion of the seat cushion 11 is moved up and down with respect to the front portion.

That is, in the present invention, the pull-out position of the drive shaft 54 is defined as the front side drive position, and the drive shaft push-in position is defined as the rear side drive position.

As described above, in the seat front-rear tilt mechanism 10 of the present invention, the operation target is switched to either the front or rear link 12 or 14 by pulling out or pushing in the drive shaft 54 in the axial direction. , Pull-out position,
The height of the front portion and the rear portion of the seat cushion 11 can be individually adjusted by rotating one of the links to be operated under the rotating operation of the knob 52 at the pushing position.

That is, according to the present invention, the operating member is excluded from the side of the seat. Since the front and rear links 12 and 14 can be both turned by operating the knob 52 that extends to the front of the seat cushion 11, it can be used for vehicles such as automobiles where a predetermined space cannot be obtained laterally. The front-rear tilt mechanism 10 can be attached to the seat, and the range of use of the front-rear tilt mechanism is expanded.

Since the front and rear links 12 and 14 can be rotated by switching the operation positions of the same knob 52, the operability is improved by simplifying the operation.

Further, since only one type of knob 52 is extended to the front of the seat cushion 11, an appearance that does not give a complicated impression is obtained, and the overall appearance quality of the seat is sufficiently improved.

A combination of worm wheels 38, 40 and worms 42, 44 is provided for each of the front and rear sides, and a drive shaft integrally having engaging pieces 56, 58 engageable with an engaging portion 48 of the worm. Since it suffices to continuously insert the 54 into the insertion hole 50 of each worm, the seat forward / backward tilt mechanism 10 with improved operability can be easily secured without complicating the configuration.

Here, the biasing force of the return spring 66 is applied to the drive shaft.
54, and the biasing force may bias the drive shaft in either the pull-out direction or the push-in direction. In addition,
The embodiment of the present invention exemplifies a configuration in which the drive shaft 54 is biased in the pull-out direction by the biasing force of the return spring 66.

As can be seen from FIG. 4A in addition to FIGS. 1 and 2, for example, the drive shaft 54 integrally has a pair of large-diameter engagement rings 68 which are separated and separated from each other by a predetermined distance. Formed,
The other end of the rotating arm 74 having an engagement pin 72 capable of engaging with the engagement ring at one end is pivotally attached to the bracket 76 of the side bracket 16 by a rivet 78 or the like. And
For example, each end of the return spring 66, which is a torsion spring, is locked to the rotating arm 74 and the bracket 76, respectively, so that a biasing force in the pull-out direction can be applied to the drive shaft 54.

In such a structure, the drive shaft 54 is
As shown in FIG. 4 (A), the return spring 66 is biased in the pull-out direction (left side in the figure) under the biasing force of the return spring 66, so that the engagement piece 56 of the drive shaft is moved forward by the biasing force. Is engaged with the engaging portion 48 of the worm 42. And from such a state,
As shown in FIGS. 3 and 4 (B), if the knob 52, that is, the drive shaft 54 is pushed against the biasing force of the return spring 66, the engagement piece 58 of the drive shaft engages with the rear worm 44. The portion 48 is engaged.

In other words, according to this structure, the initial position of the drive shaft 54 is regulated to the pull-out position under the biasing force of the return spring 66, and when the operating force of the knob 52 in the axial direction of the drive shaft is released. In the above, since the drive shaft is held at the pulled-out position which is the initial position, rattling of the drive shaft, generation of abnormal noise, etc. due to vibration etc. during traveling of the automobile are prevented.

Then, if the drive shaft 54 held in the pulled-out position under the biasing force of the return spring 66 is pushed in against the biasing force, the operation target of the knob 52 is the front link.
Since the link 12 is switched from 12 to the rear link 14, the position of the drive shaft can be easily clarified. Therefore, erroneous operation by the knob 52 can be reliably prevented.

In this embodiment, the pull-out position is embodied as the initial position of the drive shaft 54.
However, the pushing position may be defined as the initial position of the drive shaft. Even in such a configuration, since the operation target is switched from the rear side to the front side by pulling out the drive shaft 54 against the biasing force of the return spring 66, the same effect as described above is brought about without causing a decrease in operability. Can be secured.

Further, in this embodiment, the torsion spring is exemplified as the return spring 66, but the drive shaft 54
It suffices to deviate in a predetermined direction, and the present invention is not limited to this. For example, another spring member such as a tension coil spring may be used as the return spring.

Further, the return spring 66 has a combination of the engagement ring 68 of the drive shaft and the engagement pin 72 of the rotary arm.
However, the biasing force of the return spring may be applied to the drive shaft by other configurations.

Further, as shown in FIGS. 1 and 2, in the embodiment of the present invention, the engaging pieces 56, 58 of the drive shaft are formed separately on the front side and the rear side.
It is sufficient if the drive shaft 54 can be engaged with the front and rear worm engaging portions 48 at the pull-out position and the push-in position, respectively, and thus the present invention is not limited thereto. For example, one engaging piece is pulled out and pushed in. The engagement pieces of the worms may be alternately engaged at the position.

However, as shown in this embodiment, if the engaging pieces 56, 58 and the knob 52 are connected by the connecting shafts 60, 62 to form the drive shaft 54, the engaging pieces can be used in common and Since both connecting shafts can be shared,
By reducing the number of parts, it is possible to prevent complication of parts management during assembly.

Although the knob 52 having a substantially circular shape is illustrated as an operating member of the drive shaft 54, the operation of pulling out the drive shaft,
Since it is sufficient that the pushing operation and the rotating operation in the corresponding direction are possible, the present invention is not limited to the knob, and for example, a lever may be provided as an operation member at the tip of the drive shaft.

Further, in this embodiment, the engaging portion 48 of the worm and the engaging pieces 56 and 58 of the drive shaft are exemplified as the corresponding serrations, but the engaging portion and the drive shaft are mutually related. As long as it is a non-circular detent shape that can be fitted, it is not limited to this, and other detent shapes, for example,
The engaging portion and the drive shaft may be formed in a polygonal shape such as a hexagon.

However, if the engagement portion 48 of the worm and the engagement pieces 56 and 58 of the drive shaft are serrated, the engagement pitch of the engagement pieces with respect to the engagement portion becomes sufficiently small. Engagement with the movement of the drive shaft 54 can be reliably and easily performed. Therefore, the worm engaging portion 48,
By using the engagement pieces 56 and 58 of the drive shaft as serrations, the front-rear tilt mechanism 10 with good operability can be easily secured.

By the way, in the above-described embodiment of the present invention, it is possible to drive the front worm 42 shown in FIG. 5 (A) to the driven position, and the rear worm 44 shown in FIG. 5 (B). A drive shaft 54 is provided so as to be movable between the pushing positions. However, the drive shaft 54
The present invention is not limited to the pull-out position and the push-in position in which only either the front or rear worms 42, 44 are driven. For example, as shown in FIG. The drive shaft may be set at a center lock position where the engaging pieces 56 and 58 are simultaneously engaged.

The center lock position of the drive shaft 54 may be set and regulated by the biasing force of the return spring 66, for example.

As can be seen from FIG. 5C, the drive shaft 54
In the center lock position of, the drive shaft engaging pieces 56, 5
8 is the engaging part 48 of both the front and rear worms 42, 44
Since they are engaged with each other, due to the rotation of the drive shaft,
The front and rear links 12 and 14 are rotated synchronously in the corresponding directions.

That is, according to such a configuration, the knob 52
By only one operation of the rotation operation of the drive shaft 54, the parallel movement for simultaneously raising and lowering the front portion and the rear portion of the seat cushion 11 can be obtained, and therefore the operation for raising and lowering the seat cushion can be obtained without switching the operation target. Therefore, the parallel movement of the seat cushion 11 can be ensured without complicating the operation, and the operability is improved.

The position is not limited to the center lock position,
For example, as shown in FIG. 6 (C), the drive shaft 54 is returned to the neutral position in which the engaging pieces 56, 58 are not engaged with the engaging portions 48 of the front and rear worms 42, 44. It may be possible to set and regulate under the biasing force of. As shown in FIGS. 6 (A) and 6 (B), even in such a configuration, the front worm 42 is in the pulled-out position of the drive shaft 54 and the rear worm 44 is in the pushed-in position of the drive shaft. However, each can be driven.

In such a neutral position of the drive shaft 54 shown in FIG. 6C, since the rotational force from the drive shaft 54 is not transmitted to the worms 42, 44 at both the front and the rear, the return spring 66. At the neutral position, which is the initial position set under the biasing force of, the front and rear links 12 and 14 do not rotate even if the drive shaft is rotated under the operation of the knob 52. In other words, the front and rear links 12, 1
Since 4 does not rotate, malfunctions can be reliably prevented.

Further, in the embodiment of the present invention,
The pull-out position is embodied as a position where the front worm 42 can be driven, and the push-in position is embodied as a position where the rear worm 44 can be driven.Conversely, the push-in position is the front-side drive position. Alternatively, the pull-out position may be defined as the drive position on the rear side.

In this structure, as shown in FIG. 7A, the drive shaft engaging pieces 56 and 58 are located on the front and rear outer sides of the front and rear worms 42 and 44, respectively. The engaging portions 48 are provided on opposite sides of each worm so as to correspond to the above.

In such a structure, as shown in FIG. 7 (A), when the drive shaft 54 is pushed in, the engaging piece 56 engages with the engaging portion 48 of the front worm 42, so that the driving by the knob 52 is performed. The front link 12 is rotated by the rotation of the shaft. Further, as shown in FIG. 7 (B), when the drive shaft 54 is pulled out, the engagement piece 58 engages with the engagement portion 48 of the rear worm 44,
The rotation of the drive shaft with the knob 52 causes the rear link 12 to rotate.

Even in this structure, as shown in FIG. 7C, by setting the drive shaft 54 to the center lock position, the front and rear links 12 and 14 are simultaneously rotated by the rotating operation of the knob 52. It is possible to move.
Also, by widening the gap between the engaging pieces 56, 58,
The neutral position in which the engaging piece is not engaged with the engaging portion 48 of either of the worms 42, 44 at the rear is also shown in FIGS. 7 (A) and 7 (B).
Needless to say, it can be set in addition to the push-in position and the pull-out position shown in.

The embodiments of the present invention described above are intended to explain the present invention, and do not limit the present invention in any way. Modifications or alterations within the technical scope of the present invention may also be made. It goes without saying that all are included in the present invention.

[0057]

As described above, according to the seat back-and-forth tilt mechanism of the present invention, both the rotation of the front and rear links is made by a predetermined operation member extending forward of the seat cushion. It can be done under operation. Therefore, the front-rear tilt mechanism can be attached to a seat of an automobile or the like in which a predetermined space cannot be obtained laterally, and the range of use of the front-rear tilt mechanism is expanded.

Since the front and rear links can be rotated by switching the operation positions of the same operation member, the operability is improved by simplifying the operation.

Further, since only one type of operating member is extended to the front of the seat cushion, an appearance without giving a complicated impression is obtained, and the overall appearance quality of the seat is sufficiently improved.

Furthermore, a combination of a worm wheel and a worm is provided for each of the front and the rear, and a drive shaft integrally having an engaging piece engageable with the engaging portion of the worm is connected to the insertion hole of each worm. Since it suffices to insert the seat back and forth, it is possible to easily secure the seat forward / backward tilt mechanism with improved operability without complicating the structure.

If the drive shaft is biased to either the pull-out position or the push-in position under the biasing force of the return spring, the drive shaft will not move due to vibrations or the like at the initial position of the drive shaft when the vehicle is running. Rattling and abnormal noise are prevented. Also, if the drive shaft held in the initial position under the biasing force of the return spring is moved against the biasing force,
Since the operation target is changed by the operation member, the position of the drive shaft can be easily clarified. Therefore, it is possible to reliably prevent an erroneous operation by the operation member.

Further, if the sector lock position of the drive shaft for engaging the engaging pieces with the engaging parts of both the front and rear worms can be set and regulated based on the biasing force of the return spring, the operating member can be set. The parallel movement of the front and rear portions of the seat cushion can be simultaneously raised and lowered by only one operation of the rotation operation of the drive shaft by the, so that the parallel movement of the seat cushion can be secured without complicating the operation, and the operability is improved. Is improved.

Further, if the neutral position where the engaging pieces are not engaged with the engaging portions of both the front and rear worms can be set and regulated based on the biasing force of the return spring, the operation without intention of operation can be performed. With respect to the rotation of the member, since the front and rear links do not rotate, malfunction can be reliably prevented.

If the engaging piece and the operating member are connected by the connecting shaft to form the drive shaft, the engaging piece can be shared.
Further, since the connecting shaft can be commonly used, it is possible to prevent complication of parts management at the time of assembly by reducing the number of members.

Furthermore, if the engaging portion of the worm and the engaging piece of the drive shaft are serrated, the engaging pitch of the engaging piece with respect to the engaging portion becomes sufficiently small, and the drive shaft in the pull-out direction and the push-in direction can be made. Since the engagement accompanying the movement can be performed reliably and easily, it is possible to easily secure the front-rear tilt mechanism having good operability.

[Brief description of drawings]

FIG. 1 is a schematic front view of a front and rear tilt mechanism of a seat according to the present invention with a drive shaft pulled out, with a part thereof cut away.

FIG. 2 is a schematic perspective view of a seat front-back tilt mechanism.

FIG. 3 is a schematic front view of the front-rear tilt mechanism of the seat with the drive shaft pushed in, with a part thereof broken.

FIG. 4 is a partial plan view of the seat front-rear tilt mechanism at a drive shaft withdrawn position and a pushed-in position.

FIG. 5 is a schematic diagram showing a pull-out position, a push-in position, and a center lock position of the drive shaft in the embodiment of the present invention.

FIG. 6 is a schematic diagram showing a pull-out position, a push-in position, and a neutral position of the drive shaft in the embodiment of the present invention.

FIG. 7 is a schematic diagram showing a pull-out position, a push-in position, and a center lock position of a drive shaft in a modified example of the embodiment of the present invention.

[Explanation of symbols]

 10 Seat front-rear tilt mechanism 12, 14 Front and rear links 32, 34 Front, rear braking means 36 Braking means spindle 38, 40 Front, rear worm wheel 42, 44 Front, rear worm 48 Worm engagement Joint part 50 Worm insertion hole 52 Operation member (knob) 54 Drive shaft 56, 58 Front and rear engaging pieces 60, 62 Connecting shaft 66 Return spring

Claims (6)

[Claims] 1. Front and rear links for individually supporting a front portion and a rear portion of a seat cushion are operably connected to respective output sides of supporting shafts of corresponding braking means, and input of the supporting shafts of the braking means. In the seat front-rear tilt mechanism that allows the front and rear heights of the seat cushion to be individually adjusted by the rotation of each link associated with the rotation operation of the operation member that is linked to the side, the front and rear braking means are , A worm wheel is provided on the same side of the seat side by side, and the worm wheel is provided on the input side of the support shaft of each brake means, and the worm that meshes with the worm wheel rotates the non-circular detent-shaped engagement part. It is formed to have in the center insertion hole and is rotatably coaxially arranged for each of the front and rear, A drive shaft having an operating member that is extended to the front and rear worms is integrally formed with engaging pieces that can engage with the engaging portions of the front and rear worms. It is movably arranged in the axial direction and is continuously inserted through the insertion holes of each worm, and is rotatably supported.The drive shaft engaging pieces are pushed forward and rearward by pushing and pulling the drive shaft in the axial direction. One of the worms is engaged with the engaging portion of the worm, and the front and rear links are individually rotatable by the operation member rotating the drive shaft at the pull-out position and the push-in position. Seat front-back tilt mechanism. 2. The seat back-and-forth tilt mechanism according to claim 1, wherein the drive shaft is biased in either the pull-out direction or the push-in direction under the biasing force of the return spring. 3. Front and rear links for individually supporting a front portion and a rear portion of a seat cushion are operatively connected to output sides of corresponding support shafts of the braking means, and input of the support shaft of the braking means. In the seat front-rear tilt mechanism that allows the front and rear heights of the seat cushion to be individually adjusted by the rotation of each link associated with the rotation operation of the operation member that is linked to the side, the front and rear braking means are , A worm wheel is provided on the same side of the seat side by side, and the worm wheel is provided on the input side of the support shaft of each brake means, and the worm that meshes with the worm wheel rotates the non-circular detent-shaped engagement part. It is formed to have in the center insertion hole and is rotatably coaxially arranged for each of the front and rear, A drive shaft having an operating member that is extended to the front and rear worms is integrally formed with engaging pieces that can engage with the engaging portions of the front and rear worms. It is movably arranged in the axial direction and is continuously inserted through the insertion holes of each worm, and is rotatably supported.The drive shaft engaging pieces are pushed forward and rearward by pushing and pulling the drive shaft in the axial direction. By engaging the engaging portion of any one of the worms and rotating the drive shaft at the pull-out position and the push-in position by the operating member, the front and rear links can be individually rotated and Under the biasing force of the applied return spring, define the center lock position where the engaging pieces engage with the engaging parts of both the front and rear worms, and drive the operation member at the center lock position. axis The rotating operation, the front, the front and rear tilt mechanism of the seat, characterized in that the rotatable simultaneously rear link. 4. Front and rear links for individually supporting the front portion and the rear portion of the seat cushion are linked to the output sides of the corresponding support shafts of the braking means, respectively, and the input of the support shafts of the braking means. In the seat front-rear tilt mechanism that allows the front and rear heights of the seat cushion to be individually adjusted by the rotation of each link associated with the rotation operation of the operation member that is linked to the side, the front and rear braking means are , A worm wheel is provided on the same side of the seat side by side, and the worm wheel is provided on the input side of the support shaft of each brake means, and the worm that meshes with the worm wheel rotates the non-circular detent-shaped engagement part. It is formed to have in the center insertion hole and is rotatably coaxially arranged for each of the front and rear, A drive shaft having an operating member that is extended to the front and rear worms is integrally formed with engaging pieces that can engage with the engaging portions of the front and rear worms. It is movably arranged in the axial direction and is continuously inserted through the insertion holes of each worm, and is rotatably supported.The drive shaft engaging pieces are pushed forward and rearward by pushing and pulling the drive shaft in the axial direction. By engaging the engaging portion of any one of the worms and rotating the drive shaft at the pull-out position and the push-in position by the operating member, the front and rear links can be individually rotated and A seat front-rear tilt mechanism characterized in that it is possible to define a neutral position in which the engagement piece is not engaged with the engagement portion of either the front or rear worm under the biasing force of the applied return spring. . 5. A drive shaft is formed by a combination of front and rear individual engaging pieces; a connecting shaft that connects between the engaging pieces and between the front engaging piece and the operating member. The seat back-and-forth tilt mechanism according to any one of claims 1 to 4. 6. The seat back-and-forth tilting mechanism according to claim 1, wherein the engaging portion of the worm and the engaging piece of the drive shaft are formed as corresponding serrations.