Seat lock device

A seat lock device for fixing a rotatable seat back of a rear seat to a vehicle body includes: a striker which is disposed in the vehicle body; a lock mechanism which includes a base plate which is mounted to a seat back frame inside the seat back and has an engagement groove engaging with the striker, a latch which holds the striker in the engagement groove, a ratchet which maintains the latch in a lock direction and a release lever which moves the ratchet in a lock release direction; and a rod spring of which one end is attached to the seat back frame and of which the other end is bowed while coming into contact with the striker during a locking operation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a seat lock device and more particularly, to a seat back device which applies forward-folding torque to a seat back of a seat upon releasing a seat lock state.

2. Description of Related Art

In general, a vehicle seat includes a seat, a seat back and a head rest. JP-A-2006-248330 discloses a seat lock device which fixes the seat back of a rear seat of a vehicle so as to be able to be folded forward. When it is configured that the seat back is able to be folded forward, it is possible to move a baggage from a baggage room to a vehicle room or to use the baggage room as wide as possible. The seat lock device fixes the upper portion of the seat back to a vehicle body so as to be attached thereto or detached therefrom, thereby preventing the upper portion of the seat back from oscillating during a driving. Alternatively, a bottom portion of the seat back may be axially supported so as to rotate. JP-A-60-88638 discloses an example in which a spiral spring is mounted to the bottom portion of the seat back. When the spiral spring is used and then the seat lock device is released, it is possible to easily fold forward the seat back in a horizontal posture by a force built up in the spiral spring.

When the rear seat is heavy and strong, it is necessary for the spiral spring to build up a force enough for folding forward the seat back. This is because the seat back is rotated about one end as a base thereof in the state where the seat back is inclined at about 120 degree from the horizontal position to the rear side. When a force of the spring becomes strong, elastic force becomes strong, so that the seat back is abruptly folded forward.

When a motor for auxiliary assisting the rotation of the seat back is employed, and the seat back is rotated so as to be erected from the substantially horizontal posture, at the timing of application of a repulsion of the spiral spring, there is a fear that it is misjudged that human body or a baggage is interposed between the seat back and the vehicle body and the motor is driven to invert and the seat back is returned to its original position. This case is shown inFIG. 5. A solid line indicates a rotation cycle of a motor to which no load is applied and a dashed line indicates a rotation cycle at the time something is inserted in the seat back. This is an example in which it is erroneously detected that the repulsion force of the spiral spring corresponds to a case where something is pinched between the seat back and the vehicle body when a slope angle of the seat back, that is, a recliner reaches a position at about 30 degree.

When attempting to attach the spiral spring as a helper spring of a forward-folding operation to a rotation center, it is necessary to provide the spiral spring for generating torque large enough to endure a weight of the seat back. At this time, when a sufficient clearance between a vehicle trim and a seat is not ensured, a problem arises in that it is difficult to design a layout in which the spiral spring is attached to the vehicle without giving a foreign-object feeling to a passenger.

SUMMARY OF THE INVENTION

An object of the invention is to provide a seat lock device which applies forward-folding torque to a seat back by using a simple mechanism.

In order to achieve the above-described object, according to a first aspect of the invention, there is provided a seat lock device for fixing a rotatable seat back of a rear seat to a vehicle body, including:

a striker which is provided on the vehicle body;

a lock mechanism which includes:a base plate which is mounted on a seat back frame in the seat back and has an engagement groove engaging with the striker;a latch which moors the striker in the engagement groove;a ratchet which maintains the latch in a lock direction; anda release lever which moves the ratchet in a lock release direction; and

a rod spring including:one end attached to the seat back frame; andthe other end allowed to be bowed by coming into contact with the striker during a locking operation.

According to a second aspect of the invention provides the seat lock device according to the first aspect of the invention, wherein a surface of the striker is coated with resin.

According to the seat lock device of the first aspect, since there is provided the rod spring which is bowed while coming into contact with the striker during a lock operation, the rod spring strikes the striker upon releasing the lock operation and thus it is possible to apply forward-folding torque to the seat back. Accordingly, since the seat back is surely away from the lock mechanism, even when the seat back is rotated manually or by a motor, it is possible to continuously and easily fold forward the seat back. Since the rod spring comes into contact with the striker during the lock state, it is possible to apply forward-folding torque to the seat back continuously. For this reason, even when a vehicle body vibrates, it is possible to maintain the latch and the ratchet without clattering.

According to the seat lock device of the second aspect of the invention, since the surface of the striker is coated with resin, it is possible to prevent abnormal sound from occurring when the rod spring comes into contact with the striker.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a seat lock device according to an exemplary embodiment of the invention will be described with reference to the accompanying drawings.

FIG. 1is a sectional view illustrating a configuration of a seat lock device according to the invention. A rear seat1includes a seat (not shown), a seat back2and a head rest3. InFIG. 1, only the upper portion of the rear seat1is shown. A seat lock device50includes a lock mechanism20, a striker5and a rod spring9. The lock mechanism20is disposed in the upper portion of the seat back2of the rear seat1of a vehicle. The striker5is disposed in a vehicle body10on the left and right sides instead of the vehicle body10on the rear side shown by a slant line. InFIG. 1, the lock mechanism20engages with the striker5. The lock mechanism20is attached to a seat back frame4in the seat back2. One end of the rod spring9is attached to the seat back frame4and the other end of the rod spring9is disposed at a position in which the other end thereof is bowed while coming into contact with the striker5during a lock state. It is preferable that the rod spring9is made of spring steel. InFIG. 1, when the lock state is released, since a bottom portion of the seat back2is axially supported so as to rotate, the seat back2can be folded forward. Since forward-folding torque unit=(distance)×(force), since the rod spring9applies the fold-forward force to the lock mechanism20, when the lock mechanism20is located at the upper portion of the seat back which is far away from the axially supporting point of the bottom portion, the same torque can be obtained by small force. Thus, required repulsion force of the spiral spring can be reduced.

FIG. 2is a perspective view illustrating an attachment state of a lock mechanism, a rod spring and a striker. As shown inFIG. 2, the striker5is attached to one side of the vehicle body10. The lock mechanism20including a release lever7is attached to a pedestal6attached to the seat back frame4. The rod spring9is inserted into the pedestal6and is attached to the seat back frame4by use of yokes8aand8b. Accordingly, when the seat back frame4is folded backward, the lock mechanism20engages with the striker5and simultaneously the striker5pushes forward the front end of the rod spring9to be bowed.

FIG. 3is a perspective view illustrating the lock mechanism. As shown inFIG. 3, the release lever7, a ratchet12and a latch13are inserted between a base plate11and a side plate15. Through-holes for pins16aand16bare formed in the base plate11and the side plate15. Engagement grooves18, with which striker5engages, are formed from the center to the backside. The ratchet12is a claw which allows the latch13not to rotate in a counterclockwise direction and when the ratchet12is detached from the latch13by the release lever7, the latch13rotates in the counterclockwise direction. The latch13is provided with a concave portion19which surrounds the striker5. A stopper14made of resin is disposed in an inner side of the engagement groove18of the side plate15and restricts abnormal sound from occurring when the striker5comes into contact with the engagement groove18. Additionally, a spring17(which is shown inFIG. 4) is disposed between the ratchet12and the latch13.

FIG. 4is an explanatory view illustrating an operation of the lock mechanism.FIG. 4Aillustrates a lock state.FIG. 4Billustrates a state immediately after the lock state is released. InFIG. 4A, the striker5engages with an engagement groove18and pinched by a concave portion19of the latch13. Although the lower end of the rod spring9is bowed forward and drives to rotate the latch13in the counterclockwise direction, the ratchet12interrupts the rotation of the latch13. Here, when the release lever7is pulled upward, the ratchet12is rotated in the counterclockwise direction so that the claw is detached from the latch13. Then, as shown inFIG. 4B, the latch13is immediately rotated to a position below the ratchet12. At the same time, since the rod spring9strikes the striker5, the seat back2including the lock mechanism20moves forward by use of forward-folding torque.

FIG. 4Billustrates a state immediately before the locking operation. In the state shown inFIG. 4B, when the seat back2is strongly pushed backward, the latch13is rotated in a clockwise direction by the striker5and the striker5is pinched by the concave portion19, so that the striker5is held in the engagement groove18. Although the striker5advances forward in the engagement groove18, the striker5stops upon coming into contact with the stopper14. Meanwhile, although the rod spring9is bowed and drives to rotate the latch13in the counterclockwise direction, since the ratchet12comes into contact with the latch13, the rotation of the latch13in the counterclockwise direction is interrupted. Here, the locked state is established.

Since the rod spring9is bowed during the lock state, it is possible to maintain the latch13and the ratchet12without clattering by use of repulsion force. In the forward-folding force of the rod spring9, since the rod spring9is located a position far away from the rotation point of the bottom portion of the seat back2, it is possible to obtain large forward-folding torque by comparatively small force.

With such a configuration, since a timing that the rod spring9comes into contact with the striker5is just before the seat back2is in an erection state. In this timing, since the seat back2is substantially elected and there is not formed a large gap therebetween, there is no fear that the passenger is pinched therebetween.

Thus, as for the inclination angle of the seat back at this timing, it is preferable to set the pinch detection sensor in OFF state. According to this set condition, although the automatic returning motor is equipped, there is no fear of occurrence of such the glitch of stopping the motor at the time of generation of repulsion force of the rod spring9. Therefore, according to the present invention, with the simple construction, it is prevented from occurrence of the glitch of stopping of the motor.

The seat lock device according to the invention may be applied to a rotatable rear seat of a vehicle.

While the invention has been described in connection with the exemplary embodiments, it will be obvious to those skilled in the art that various changes and modification may be made therein without departing from the present invention, and it is aimed, therefore, to cover in the appended claim all such changes and modifications as fall within the true spirit and scope of the present invention.