GB2451981A

GB2451981A - Reclining device comprising deformable guides

Info

Publication number: GB2451981A
Application number: GB0821407A
Authority: GB
Inventors: Ishihara Yoshitaka; Esaki Takuto; Hara Kazuyoshi
Original assignee: Imasen Electric Industrial Co Ltd
Current assignee: Imasen Electric Industrial Co Ltd
Priority date: 2006-02-16
Filing date: 2008-11-24
Publication date: 2009-02-18
Anticipated expiration: 2027-02-16
Also published as: GB0821407D0; GB2451981B

Abstract

A reclining device comprises a base plate 10, a gear plate 20 having inner teeth 21 and being rotatably assembled with the base plate, two pairs of fixed guides 30 formed on the base plate, and a pair of lock gears 40 each having outer teeth 41 capable of being engaged with the inner teeth of the gear plate, each of the lock gears being disposed between a respective pair of fixed guides so as to slide along one of the fixed guides. A cam 50, biased by a pair of springs 60 and drivable by a shaft 70, controls movement of the lock gears to engage them with the gear plate. The mechanical strength of the fixed guides is set to be lower than that of the gear plate and the lock gears, such that when a large load is applied to the reclining device, the lock gears push the fixed guides to deform them and cause outer end portions 31 to contact the inner teeth of the gear plate to prohibit inclination movement of the seat back.

Description

SPECIFICATION

RECLINING DEVICE

Technical Field

(0001] The present invention relates to a reclining device for vehicle seats, more particularly to a reclining device that eliminates mechanical play in a front-rear direction of a seat back to prevent unintended inclination movement of the seat back upon a collision of a vehicle.

Background Art

[0002] In many cases, a vehicle seat is provided with a various kinds of angle/positional adjusting mechanisms to fit to a size of body and posture of a sitting occupant. In such mechanisms, a reclining device, which adjusts the angle of a seat back with respect to a seat cushion, is the most basic seat adjusting mechanism. Therefore, such a reclining device is mounted on most vehicle seats.

[0003] There are two types of reclining devices; i.e., powered-type reclining devices in which the seat back is operated with a power of an electric motor, and manual type reclining devices in which a sitting occupant operates the seat back manually. Compared to the powered-type reclining devices, the manual type reclining devices have a simpler structure. In the manual type reclining devices, the risk of failure is smaller and the manufacturing cost thereof is lower. Therefore, manyvehicles are equipped with manual type reclining devices in these days.

[0004] In some manual type reclining devices, inner teeth are arranged to engage with outer teeth to lock the reclining device. The outer teeth are arranged to be movable toward/away from the inner teeth. When the engagement between the inner teeth and the outer teeth is released, a force imparted by a spring rotates the seat back. Since manual type reclining devices have an advantage that the seat back can be inclined swiftly with an easy operation of a lever, manual type reclining devices are mounted on many vehicles in these days.

[0005] However, in the manual type reclining devices, the lock gear having the outer teeth has to be sandwiched and supported between a pair of guide portions. At the same time, the lock gear has to be allowed to slide between the guide portions.

Therefore, a gap is generated accordingly between the lock gear and the guide portions. When the reclining device is mounted on a vehicle seat, the gap causes a mechanical play in a front-rear direction of the seat back. Although such mechanical play does not directly affect the safety of an occupant, it gives an uncomfortable feeling to the occupant.

Conventionally, as a solution to the above problem, a reclining device is disclosed in Patent document 1.

(0006) In the reclining device disclosed in the patent document 1, first of all, a pair of lock gears (support and receiving plates), each having a generally triangle shape, is formed. The reclining device is composed of these two component members that are slidably coupled to abut on the respective inclined faces. The reclining device is arranged so that, when one member is pressed from the rear side by a rotatable cam, outer teeth of the lock gear can be engaged with a row of teeth (inner teeth).

According to such device, an inclined face of one lock gear is pushed out while sliding on the inclined face of the other lock gear. Between guide portions (within a concave portion), the two pieces of the lock gear are pushed so as to be wider and the lock gear (support and receiving plates) is brought into close contact with side faces of the guide portion (concave portion) . As a result, a gap between the lock gear and the guide portion is eliminated and the mechanical play in the front-rear direction of the seat back is eliminated. In this point, the reclining device disclosed in the patent document 1 is an outstanding technique.

[0007] However, the reclining device disclosed in the patent document 1 employs a structure such that the cam pushes one lock gear only to press the other lock gear against the guide. Therefore, there is a problem that, when one lock gear is locked first, the other lock gear may be stopped in an unlocked state.

[0008) As a solution to the above problem, a reclining device has been proposed in Patent document 2. In the reclining device disclosed in the patent document 2, it is arranged so that a first cam pushes a second cam and a lock gear and the second cam presses the lock gear onto a guide portion, to thereby bring the lock gear into close contact with the guide portion. With this arrangement, a gap between the lock gear and the guide is eliminated and the mechanical play in the front-rear direction of the seat back can be eliminated. In this point, the reclining device disclosed in the patent document 2 is an outstanding technique.

(0009] However, the reclining device disclosed in the patent document 2 employs a structure such that the first cam pushes the second cam and the lock gear simultaneously. Therefore, a high precision is required on the component members. Particularly, when the second cam is formed in a circular shape, such a problem as a catch of a component member, which is experienced in the device disclosed in the patent document 1, can be eliminated. However, there is a possibility that such a loss as useless turn of the second cam may occur.

[0010] on the other hand, in the manual type reclining device, even in a state that the inclination movement of the seat back is locked, the lock gear, which is pushed out by the cam, is just pressed against the inner teeth of the gear plate to thereby maintain the engagement therebetween.

Therefore, when an overload is applied to the reclining device upon a collision of a vehicle equipped with the reclining device or the like, the lock gear may be disengaged from the inner teeth of the gear plate. Under such situation, the seat back may be inclined unintentionally. As a solution to the above problem, the applicant of the present invention has proposed a reclining device disclosed in Patent document 3.

[0011] The reclining device disclosed in the patent document 3 employs the following arrangement.

That is, in an ordinary state, a movable guide pushes a lock gear. When an overload is applied to the reclining device upon a collision of a vehicle (in an emergency situation) or the like, the movable guide comes into contact with the inner teeth of a gear plate and the inner teeth are elastically deformed and engaged with the inner teeth. With this arrangement, upon an emergency situation, the movable guide is firmly fixed with the gear plate.

As a result, unintended inclination movement of the seat back can be prevented. In this point, the reclining device disclosed in the patent document 3 is an extremely outstanding technique.

[0012] However, in the device disclosed in the patent document 3, the movable guide of the reclining device has to fulfill both of the following requirements. That is, during ordinary operation, the movable guide has to hold the lock gear without gap; and upon an emergency, the movable guide has to engage with the gear plate. Therefore, a high precision is required for machining and assembling the component parts constituting the reclining device. It burdens in an aspect of manufacturing cost and manufacturing efficiency.

Patent document 1: Japanese Examined Patent Application Publication No. 7-12325 Patent document 2: Japanese Unexamined Patent Application Publication No. 11-155674 Patent document 3: Japanese Unexamined Patent Application Publication No. 2005-230300

Disclosure of the Invention

Problems to be Solved by the Invention (0013] The present invention has been proposed in view of the above problems. Objects of the invention are as listed below.

(1) To provide a reclining device capable of eliminating mechanical play in a front-rear direction of a seat back during normal operation; particularly, to provide a reclining device, which is capable of reliably performing locking and releasing, at a low cost.

(2) To provide a reclining device, at a low cost, capable of preventing unintended inclination movement of the seat back upon an emergency like a collision of a vehicle or the like, with a simple structure.

Means to Solve the problems (0014] In order to solve the above problems, the invention employs the following means.

[0015] According to the present invention there is a reclining device, comprising: a base plate 10 fixed to either one of a seat cushion or a seat back; a gear plate 20 having inner teeth 21, the gear plate being rotatably assembled with the base plate 10 and fixed to the other one of the seat cushion or the seat back; two pairs of fixed guides 30 formed on the base plate 10; a pair of lock gears 40 each having outer teeth 41 capable of being engaged with the inner teeth 21 of the gear plate 20, each of the lock gears being disposed between the respective pair of fixed guides 30 so as to slide along one of the fixed guides 30; a cam 50 that controls the movement of the pair of lock gears 40 to engage the pair of lock gears 40 with the inner teeth 21 of the gear plate 20; a pair of springs 60 that imparts a rotational force to the cam 50 to keep the lock gears 40 being engaged with the inner teeth 21 of the gear plate 20; and a center shaft 70 capable of driving the cam 50 to rotate to thereby disengage the pair of lock gears 40 from the gear plate 20, wherein the mechanical strength of the fixed guides 30 is set to be lower than that of the gear plate 20 and the lock gears 40, when a large load is applied to the reclining device, the lock gears push the fixed guides 30 to deform the same and cause the outer end portion 31 of the fixed guides to come into contact with the inner teeth 21 of the gear plate 20 to thereby prohibit the inclination movement of the seat back.

[0016) The fixed guides 30 is preferably disposed so that the outer end portion 31 thereof is positioned close to the front end of the inner teeth 21 of the gear plate 20, when the fixed guides 30 are deformed, the outer end portion 31 thereof bites into the inner teeth 21 of the gear plate 20.

[0017) The fixed guides are preferably formed in a thickness such that, when the base plate 10 and gear plates 20 are assembled with each other, the fixed guides 30 comes into substantially close contact with the gear plates 20, when the fixed guides 30 are deformed, the gear plates 20 restricts the deformation in a thickness direction thereof.

(0018) The present invention may further comprise a link plate 120 that rotates along with the cam 50 to pull the lock gears 40 inward when the cam is rotated to disengage the lock gears 40 from the inner teeth 21 of the gear plate20, wherein the link plate 120 includes a cut-off 125 in an outer periphery at a point where, when the lock gears 40 are engaged with the inner teeth 21 of the gear plate 20, comes into contact with the outer end portion of the fixed guides 30 in the outer periphery of the link plate 120, when the fixed guides 30 are deformed, the deformation in a thickness direction thereof is released from the cut-off 125 of the link plate 120 to allow the same to come into contact with the gear plate 20.

Effect of the Invention [0019) The effects obtained by employing the above means are as described below.

[0020] The reclining device 200 according to the first aspect of the invention is provided with a pair of movable guides 100. Each of the movable guides has a wedge-like shape the width of which gradually decreases from the outer end toward the inner end. Each of the movable guides 100 is disposed between the lock gear 40 and the fixed guide 30. Each of the movable guides 100 is imparted with a force toward an inner direction of the base plate 10 by the spring. Therefore, each of the movable guides 100 is sandwiched by the lock gear 40 and the fixed guide therebetween. The fixed guide 30, the lock gear and the movable guide 100 are maintained in a close contact with each other and a gap between the respective members is eliminated. Consequently, the first aspect of the invention obtains an effect that a mechanical play in a front-rear direction of the seat back can be reliably eliminated, and the lock gear 40 and the movable guide 100 can be reliably locked with each other and released from each other.

[0021) In the reclining device 200 according to the second aspect of the invention, each of the movable guides 100 is arranged so that the sliding face at the lock gear 40 side is parallel to a movement direction of the lock gear 40. Therefore, such a problem that the movable guide 100 fixedly catches the lock gear 40 can be prevented. According to the second aspect of the invention, the mechanical play in a front-rear direction of the seat back can be reliably eliminated. Further, such effect that the movable guides 100 can be reliably locked and unlocked is obtained.

[00221 In the reclining device 200 according to the third aspect of the invention, the lock gears 40 is formed in a shape the width of which gradually decreases from the inner end toward the outer end.

The sliding face of the lock gear 40 at the fixed guide side is arranged to be parallel to a movement direction of the lock gear 40. Therefore, the lock gear 40 is formed with an inclined surface at the movable guide 100 side. The movable guide 100 having a wedge-like shape is disposed between the inclined surface and the fixed guide 30. The sliding faces are held in a close contact with each other, and the outer teeth 41 of the lock gear 40 are engage with the inner teeth 21 of the gear plate 20. Thereby, the rotation of the gear plate 20 is locked (that is, not to recline) . On the other hand, to release the locking of the reclining, the center shaft 70 is rotated to disengage the outer teeth 41 of the lock gears 40 from the inner teeth 21 of the gear plate 20. Here, in the third aspect of the invention, the contact face between the lock gear 40 and the movable guide 100 is inclined with respect to a movement direction of the lock gear 40. When the lock gear is pulled in an inner direction, the lock gear 40 and the movable guide 100 can be separated without generating almost any friction therebetween.

Therefore, according to the third aspect of the invention, the lock gear 40 can be smoothly pulled inwardly without particularly pushing out the movable guide 100 by the link plate 120, and thus the lock is released. Therefore, in addition to the effect of the first aspect of the invention, such effect that reclining device 200 can be constituted with a fewer number of component parts is obtained.

[00231 In the reclining device 200 according to the fourth aspect of the invention, the movable guides 100 are attached to the respective ends of the torsion spring 110. Therefore, it is not required to form any engagement portion for the spring on the base plate 10. Therefore, according to the fourth aspect of the invention, the number of the component parts is reduced and the structure thereof is simplified. Accordingly, in addition to the above-described effects, such an effect that the assembling of the reclining device 200 is facilitated is obtained. Thus, the manufacturing cost of the reclining device 200 can be saved and the durability thereof is increased.

[0024] In the reclining device 200 according to the fifth aspect of the invention, each the two torsion springs 110 is attached to the cam 50 at one end thereof and one of the movable guides 100 at the other end thereof, thus the respective the movable guides 100 is pulled along a diagonal line. Needless to say, a force is imparted inward to the movable guides 100; and the cam 50 is uniformly imparted with a rotational force from two directions. Therefore, according to the fifth aspect of the invention, the cam 50 is prevented from being imparted with a force in an eccentric direction. The cam 50 is rotated at the center of the base plate 10. That is, the pushing force of the cam 50 is imparted uniformly to the both lock gears 40. The outer teeth 41 of the lock gears engage with the inner teeth 21 of the gear plate respectively. Thus, the lock is achieved reliably.

[0025) In the reclining device 200 according to the sixth aspect of the invention, each of the movable guides 100 has the outer teeth 102 at the outer end thereof. Therefore, when an overload is applied to the reclining device 200 upon a collision of a vehicle or the like, a rotational load is transmitted from the gear plate 20 to the lock gears 40. Accordingly, the lock gears 40 function to push the movable guides between the fixed guides 30 and the same respectively. Here, each of the movable guides 100 is formed in a shape the width of which gradually decreases from the outer end toward the inner end.

Therefore, each of the movable guides 100 is pushed man outerdirectionof thebaseplate 10. Therefore, the outer teeth 102, which are formed at the outer end of the movable guides 100, move toward the inner teeth 21 of the gear plate 20 and is engaged therewith.

Thus the movable guides 100 prevent the gear plate from rotating together with the lock gears 40.

Therefore, according to the sixth aspect of the invention, when an overload is applied to the reclining device 200 upon a collision of a vehicle or the like, the movable guides 100 prevent the rotation of the gear plate 20 together with the lock gears 40. Thus, unintended inclination movement of the seat back can be prevented upon a collision of a vehicle.

[0026] In the movable guides 100 of the reclining device 200 according to the seventh aspect of the invention, a gentle two-step shape is formed including the contact portion 103 and step portion 104 at the fixed guide 30 side. Therefore, the movable guide 100 is in a close contact with the fixed guide 30 at the contact portion 103 only.

Consequently, according to the seventh aspect of the invention, even when a small error is generated in the dimensions of the formed fixed guide 30, the movable guide 100 naturally comes into close contact with the fixed guide 30 at the outer end side thereof.

Thus, the mechanical play in a front-rear direction of the seat back can be reliably prevented.

[0027] In the reclining device 200 according to the eighth aspect of the invention, when the cam 50 is rotated to release the lock, the link plate 120 that rotates along with the cam 50 pushes the movable guides 100 outward. That is, when the movable guides having a wedge-like shape, which are in a close contact with the fixed guide 30 and the lock gear 40 therebetween, are pushed outward, a gap is generated between the movable guide 100 and the lock gear 40 allowing the lock gear 40 to slide. Consequently, according to the eighth aspect of the invention, in addition to the above-described effects, such effect that the lock can be further reliably released is obtained.

[0028) According to the ninth aspect of the invention, in the reclining device 200 set forth in the first to eighth aspect of the invention, the base plate 10 is laser-welded to the seat cushion bracket 300 or seat back bracket 300 constituting the seat frame of the vehicle seat on which the seat frame is mounted. Embossprocessingpointsforweldingonthe base plate 10 can be reduced, and it is not required to form a large opening in the bracket 300. Therefore, according to the ninth aspect of the invention, the plastic processing on the component parts can be reduced to the minimum. Thus, a high strength vehicle seat can be provided.

[00291 In the reclining device 200 according to the tenth aspect of the invention, the mechanical strength of the fixed guides 30 formed integrally with the base plate 10 is set to be lower than that of the gear plate 20 and the lock gears 40. Therefore, when an overload is applied to the reclining device upon a collision of a vehicle or the like, the lock gears 40 push the fixed guides 30 and deform the fixed guides 30. Thereby, the outer end portion 31 of the fixed guides 30 is brought into contact with the inner teeth 21 of the gear plate 20. Thus, the gear plate 20 is firmly fixed and the inclination movement of the seat back is prohibited.

Consequently, according to the tenth aspect of the invention, even in an emergency upon a collision of a vehicle or the like, unintended inclination movement of the seat back can be prevented. Further, since the fixed guides 30 are formed integrally with the base plate 10, number of the component parts can be reduced and the structure thereof is simplified facilitating the assembly thereof. Thus, effects that manufacturing cost of the device can be reduced and the durability thereof is increased are obtained.

[0030] In the reclining device 200 according to the eleventh aspect of the invention, the outer end portion 31 of the fixed guides 30 and the front end of the inner teeth 21 of the gear plate 20 are disposed as close to each other as possible. Even a small deformation of the fixed guide 30 can cause the outer end portion 31 thereof to bite into the inner teeth 2]. of the gear plate 20. Consequently, according to the eleventh aspect of the invention, the effect of the above-described tenth aspect of the invention is obtained. That is, unintended inclination movement of the seat back can be more reliably prevented.

[0031] In the reclining device 200 according to the twelfth aspect of the invention, the fixed guides are formed in a thickness so that the same comes into substantially close contact with the gear plate (when the base plate and the gear plates are assembled) . That is, a gap between the base plate and the gear plates in a direction of the shaft axle is set to be as small as possible. Therefore, when the fixed guides are deformed, the gear plate restricts the deformation of the fixed guide in the thickness direction. Almost all deformation amount of the fixed guide can be utilized for biting into the inner teeth of the gear plate. Consequently, according to the twelfth aspect of the invention, the effect of the above-described first aspect of the invention is obtained. That is, unintended inclination movement of the seat back can be more reliably prevented.

[0032) The link plate 120 of the reclining device according to the thirteenth aspect of the invention has the cut-off 125 in the periphery end thereof. Therefore, when an overload is applied to the reclining device 200 upon a collision of a vehicle or the like, a part of the deformed lock gear 30 runs out from the cut-off 125 and engages with the gear plate 20. That is, according to the thirteenth aspect of the invention, the shifting direction of the material of the deformed fixed gears 30 can be desirably controlled. Thus, the fixed guides 30 can be engaged with the gear plate 20 more effectively.

Best Mode for Carrying Out the Invention

[0033] Reclining device 200 according to the invention will be described below with reference to the embodiments.

[0034] (Embodiment 1) Figs. 1-4 illustrate a reclining device 200 according to an embodiment 1. The reclining device according to the embodiment 1 includes a base plate 10, a gear plate 20, fixed guides 30, lock gears 40, a cam 50, springs 60, a center shaft 70, movable guides 100, a spring and a link plate 120.

Hereinafter, the respective component elements will be described.

[0035] The base plate 10 is abase of the reclining device 200. The base plate 10 is fixed to either one of a seat cushion or a seat back of a vehicle seat.

The base plate 10 has to be strong enough to support a load of the seat back and weight of an occupant.

Therefore, thebaseplate 10 is formedof a steal plate processed by means of press working or cutting.

According to the embodiment 1, the base plate 10 is formed in a circular shape in its external shape by carrying out press working ona steal plate. The base plate 10 is also formed with fixed guides 30. The fixed guides 30 are fixed to the seat cushion.

[0036) The gear plate 20 is assembled with the base plate 10 so as to rotate with respect to the gear plate 20, and is fixed to either another one of the seat cushion and the seat back of the vehicle seat (not fixed with the base plate 10) . The gear plate is formed with inner teeth 21 on the inner periphery located at the side opposite to a face fixed to the seat back (or the seat cushion) . The inner teeth 21 can be engaged with outer teeth 41 of the lock gears 40. With the engagement with the lock gear 40, the seat back is locked from inclining in a front-rear direction. The gear plate 20 has to be strong enough to support the load of the seat back and the weight of an occupant. Therefore, the gear plate 20 is formed with a steal plate by means of press working or cutting. According to the embodiment 1, the gear plate 20 is formed of a steal plate in a circular shape in its external shape by carrying out press working thereon and is formed with inner teeth 21. The gear plate 20 is fixed to the seat back.

[0037] The base plate 10 is integrally formed with two pair of the fixed guides 30. Each pair of the fixed guides 30 is located eccentrically at two points to sandwich and hold the lock gear 40 and the movable guide 100. Since the load of the seat back and the weight of an occupant converge on the fixed guides 30, the fixed guides 30 have to be strong enough to support such weight. Therefore, the fixed guides are formed of a sheet of steal plate processed by means of press working or cutting. According to the embodiment 1, the fixed guides 30 are formed by pressing a sheet of steal plate to protrude therefrom using a die from the rear side thereof at the same time when the base plate 10 is formed by carrying out the press working on the sheet of steal plate.

[0038] The side faces of the lock gears 40 are formed to be parallel with each other so that the lock gears 40 are slidable between the fixed guides 30.

Each of the lock gears 40 is formed with outer teeth 41 on one edge connecting the side faces respectively so as to be engaged with the inner teeth 21 of the gear plate 20. When the outer teeth 41 of the lock gear 40 are engaged with the inner teeth 21 of the gear plate 20, primary the outer teeth 41 bears the loadfromthegearplate2o. Therefore, the lockgear has to be strong enough to bear the load.

Accordingly, the lock gear 40 is formed of a sheet of steal plate by carrying out press working or cutting to form a base metal. After that, quench hardening or forging is carried out on the base metal.

According to the embodiment 1, the lock gear 40 is formed of a sheet of steal plate by carrying out the press working and then carrying out the quench hardening. Further, each of the lock gears 40 is formed with a projection 42 so that a link plate 120 is connected. Furthermore, although not clearly expressed on the figures, each of the lock gears 40 is formed so that central area of the sliding faces is concaved at both sides thereof. That is, the central area is formed in a concaved shape at the both sides (refer to Fig. 4) . Therefore, the lock gear comes into contact with the fixed guide 30 or the movable guide 100 at two points near an outer end portion and an inner end portion (with reference to the base plate) . By arranging as described above, compared to the case where the respective component elements are formed in a complete plane and brought into contact with each other, the sliding of the lock gear 40 is facilitated.

[0039) The cam 50 is disposed in a substantially central position of the base plate 10, and the shaft is inserted therethrough. The cam 50 is rotated integrally with the shaft 70 to control the movement (sliding) of the lock gear 40. That is, the rotation of the cam 50 controls the lock gear 40 to engage with the gear plate 20 and to release therefrom.

Accordingly, the rotation of the cam 50 locks inclination movement of the seat back mounted with the reclining device 200 in a front-rear direction and releases the same from the lock. According to the embodiment 1, the cam 50 is formed with a rectan gular hole 52 through which a rectangular-shaped portion 71 of the center shaft 70 is inserted. The cam 50 is also formed with two projections 51 for permitting the link plate 120 to be connected therewith.

[0040) The spring 60 imparts a rotational force to the cam 50 to keep the lock gear 40 being engaged with the inner teeth 21 of the gear plate 20.

According to the embodiment 1, the spring 60 is a spiral spring. One end of the spring 60 is engaged with the cam 50, and the other end thereof is engaged with an engagement projection formed on the base plate 10. The invention is not limited to the above-described arrangement. It may be arrange so that a spring (not shown) provided to the center shaft may impart a rotational force.

[0041) The base plate 10 and the gear plate 20 are formed with a through hole respectively in the central area thereof, and the center shaft 70 is inserted therethrough to pivot the base plate 10 and the gear plate 20 coaxially. The center shaft 70 is mounted with an operation lever 72, which is a member separate from the center shaft 70. The cam 50 and the link plate 120 are located between the base plate and the gear plate 20 and inserted by the center shaft 70. When an occupant manually operates the operation lever 72, the cam 50 and the link plate 120 are rotated integrally; and thereby the lock gear 40 is engaged with the gear plate 20 or disengaged therefrom. According to the embodiment 1, the center shaft 70 is formed of steel material in a manner of cutting. To be more precisely, in a generally central area in a longitudinal direction of the center shaft 70, a rectangular-shaped portion 71 is formed. The rectangular-shaped portion 71 is inserted into a rectangular hole 121 formed in the cam 50 and the link plate 120. One end portion of the center shaft 70 is arranged to attach the operation lever 72. The other end portion of the center shaft 70 is formed with a serration 73 for allowing a link shaft (not shown) to be connected therewith. The reclining device 200 is mounted to the vehicle seat by means of a pair of joint portions located at the right and left sides thereof.

Therefore, the rotation of the right and left cams of the reclining device 200, which are located at the right and left sides of the seat, has to be synchronized via the link shaft.

[0042] Each of the movable guides 100 is formed in a wedge-like shape so that the width thereof gradually becomes smaller from one end toward the other end.

Each of the movable guides 100 is slidably interposed between the lock gear 40 and the fixed guide 30. The pair of the movable guides 100 is provided with a spring engaged therewith, which will be described later. The spring imparts a force to the pair of movable guides 100 in an inner direction of the base plate 10. With the above-described arrangement, each of the movable guides 100 is constantly positioned between the lock gear 40 and the fixed guide 30 respectively. Thus, the fixed guide 30, the lock gear 40 and the movable guide 100 are brought into a close contact with each other, and gapes between the respective members are eliminated. As a result, the mechanical play of the seat back in a front-rear direction is eliminated. Also, the movable guide 100 is disposed so that the sliding face at the side of the lock gear 40 is parallel to a movement direction of the lock gear 40. Therefore, the lock gear 40 is prevented from being caught by the movable guide 100. According to the embodiment 1, each of the movable guides 100 is formed of a steal plate pressed into a wedge-like shape and hardened by quenching. Further, the each of the movable guides 100 is formed with a projection 101 for connecting to the link plate 120, which will be described later. Although not clearly illustrated in the figures, the movable guide 100 is formed with concave portions at both sides in the central area of the sliding face. That is, each of the movable guides 100 is formed in a concave shape in the central area of the both sides thereof (refer to Fig. 4).

Therefore, the movable guide 100 abuts on the fixed guide 30 or the lock gear 40 at two points of outer edge portion and inner edge portion thereof (with reference to the base plate) . Compared to the case where the respective component elements are formed in a complete plane shape and brought into a close contact with each other, this arrangement facilitates the sliding movement of the movable guides 100.

[00433 The spring is engaged with the movable guides 100 each interposed between the fixed guide and the lock gear 40. The spring imparts a force to the movable guides 100 toward the inner side of the base plate 10. According to the embodiment 1, the spring is composed of a torsion spring 110 that is an arc-shaped rod member. Each of the movable guides 100 is engaged with the torsion spring 110, the end portions of which are bent to form an engagement portion respectively. The torsion spring 110 imparts a force to the movable guides 100 toward each other. The invention is not limited to the above-described arrangement. It may be arranged so that the base plate 10 is formed with engagement portions (not shown), and each of the movable guides is imparted with a force by a separate spring.

[0044] When the cam 50 rotates and the engagement of the lock gear 40 with the inner teeth 21 of the gear plate 20 is released, (more preferably, prior to the engagement of the lock gear 40 with the inner teeth 21 of the gear plate 20 is released), the link plate 120 rotates along with the cam 50 to push the movable guides 100 outward. According to the invention, in order to eliminate a gap between the fixed guide 30 and the lock gear 40, which causes mechanical play, each of the movable guides 100 is interposed between the fixed guide 30 and the lock gear 40 to keep them in a close contact state. In such state, there may be a case such that, the lock gear 40 sticks to the fixed guide 30 and the movable guide 100 therebetween. And the engagement between the lock gear 40 and the gear plate 20 may not be released only by rotating the cam 50 to release the lock of the seat back for restraining the inclination movement. Therefore, when (prior to) pulling the lock gears 40 inward of the base plate 10, the movable guides 100 are pushed outward to thereby release the close contact between the movable guides 100 and the lock gears 40 so as to permit the lock gears 40 to swing freely. According to the embodiment 1, the link plate 120 is composed of a circular-shaped thin plate. In a central position of the link plate 120, a rectangular hole 121 is formed for permitting the rectangular-shaped portion 71 to be inserted through.

The link plate 120 is formed with round holes 122 for allowing the projections 51 of the cam 50 to be inserted therethrough. The link plate 120 is also formed with generally sector-shaped holes 123 that permit the projections 42 of the lock gears 40 to be insert therethrough. And the link plate 120 is also formed with concave portions 124 on which projections 101 of the movable guides 100 abut at two points in the circular-shaped outer periphery. The link plate is arranged so that, when the link plate 120 is rotated, the outer edge of the concave portions 124 comes into contact with the projections 101 of the movable guide 100 at a timing earlier than the timing that the outer edge of the generally sector-shaped holes 123 comes into contact with the projection 42 of the lock gear 40. With this arrangement, when the center shaft 70 is rotated to release the lock of the reclining device 200, the concave portions 124 of the link plate 120 push the projections 101 of the movable guide 100 outward first. And then, the generally sector-shaped holes 123 of the link plate 120 allow the lock gear 40 to enter therein smoothly. Thus, the load on the respective component members can be reduced.

[0045) Now, referring to Figs. 1-4, the operation of the reclining device 200 according to the embodiment 1, which is arranged as described above, will be described.

(0046] In the reclining device 200 according to the embodiment 1, when the seat back is locked to restrain the inclination movement of in the front-rear direction, an occupant releases the operation lever 72. When the operation lever 72 is released, the cam 50, to which a force is imparted in a counterclockwise in the figures by the springs 60, rotates as illustrated in Figs. 1 and 3. The lock gears 40 is pushed outward to slide along the fixed guides 30 in the base plate 10, and the outer teeth 41 of the lock gears 40 engage with the inner teeth 21 on the inner periphery of the gear plate 20. Thus, the seat back is locked and the inclination movement in the front-rear direction is restrained. At this time, the movable guides 100 is strongly inserted between the lock gear 40 and the fixed guide 30 being imparted with a force by the spring. And thus, the fixed guide 30, the lock gear 40 and the movable guide come into close contact with each other and the gap among the respective component members is eliminated. As a result, in the state that the seat back is locked and the inclination movement is restrained, the mechanical play in the front-rear direction is prevented.

[0047) On the other hand, in the reclining device according to the embodiment 1, when the seat back is unlocked from the restraint of the inclination movement in the front-rear direction, the occupant pulls up (or pushes down) the operation lever 72.

When the operation lever 72 is rotated, the center shaft 70 to which the operation lever 72 is attached rotates. At this time, the cam 50 and the link plate 120, through which the center shaft 70 is inserted as illustrated in Fig. 2 and Fig. 4, are also rotated simultaneously. When the cam 50 rotates, a gap is generated between the cam 50 and the lock gear 40.

Also, when the link plate 120 rotates, the outer edge of the concave portions 124 of the link plate come into contact with the projections 101 of the movable guides 100, and push the movable guides 100 outward in the base plate 10. Thus, the close contact among the movable guides 100, the fixed guides 30 and the lock gears 40 is released. After that, the outer edge of the generally sector-shaped holes 123 of the link plate 120 come into contact with the projections 42 of the lock gears 40. As a result, the lock gears are smoothly pulled inward, and the seat back gets into a state that the inclination movement can be performed in the front-rear direction. The above-described series of operation are performed substantially simultaneously while slightly differentiating the timing.

[00483 (Embodiment 2) Fig. 5 illustrates a reclining device 200 according to an embodiment 2. The reclining device according to the embodiment 2 is identical to the embodiment 1 in many points. Therefore, a point particularly different from that in the embodiment

1 is described, and descriptions on the identical

points are omitted. In the embodiment 2, a vertical torsion spring 60 imparts a rotational force to the cam 50 as shown in Fig. 5. In the embodiment 2, the link plate 120 is not particularly shown for the

convenience of description. Needless to say, the

reclining device 200 may be provided with the link plate 120. According to the embodiment 2, the single torsion spring 60 imparts the rotational force to the cam50. The recliningdevice200 canbe achievedwith a fewer component parts than those in the embodiment 1.

(00491 (Embodiment 3) Fig. 6 illustrates a reclining device 200 according to an embodiment 3. The reclining device according to the embodiment 3 is identical to the embodiment 1 in many points. Therefore, a point particularly different from that in the embodiment

1 is described, and descriptions on the identical

points are omitted. In the embodiment 3, a pair of torsion springs 110, the other end of which is attached to the pair of the movable guides 100 respectively, imparts a rotational force to the cam as shown in Fig. 6. Accordingly, the pair of the torsion springs 110 is engaged with the cam 50 and the pair of the movable guides 100. The pair of the torsion springs 110 disposed on a diagonal line symmetrically with respect to the center shaft 70.

Therefore, the cam 50 is uniformly imparted with a rotational force from two directions. Consequently, according to the embodiment 3 the cam 50 is prevented from being given with a force in an eccentric direction. Therefore, the cam 50 can be rotated on the center of the base plate 10. That is, a pushing force from the cam 50 is uniformly imparted to the both of the pair of lock gears 40. Accordingly, the outer teeth 41 of the pair of lock gears 40 are engaged with the inner teeth 21 of the gear plate 20 and are reliably locked. In the embodiment 3, the pair of torsion springs 110 is attached to the cam 50, and the respective movable guides 100 and the torsion springs 110 are disposed on a diagonal line with respect to the center shaft 70. However, the invention is not particularly limited to the above arrangement. That is, if the rotational force can be imparted by disposing the cam 50 on the diagonal line, the following arrangement may be employed.

That is, the movable guides 100 may be disposed adjacent to the engagement portion on the cam 50, and the cam 50 and the movable guides 100 may be linked with each other. The pair of torsion springs 110 is not limited to the configuration shown in Fig. 6. Any of configurations illustrated in Fig. 7 or Fig. 8 may be employed. In the embodiment 3, the link plate 120 is not particularly shown for the convenience of description. Needless to say, the link plate 120 may be provided.

(0050) (Embodiment 4) Fig. 9 illustrates a reclining device 200 according to an embodiment 4. The reclining device according to the embodiment 4 is identical to the embodiment 1 in many points. Therefore, a point particularly different from that in the embodiment

1 is described, and descriptions on the identical

points are omitted. As shown in Fig. 9, in the embodiment 4, each of the lock gears 40 is formed in a shape that the width gradually decreases from the inner end toward the outer end. The sliding face of each the lock gears 40 at the fixed guide 30 side is arranged to be parallel to a movement direction of the lock gear 40. Therefore, each of the lock gears is formed with an inclined surface at the movable guide 100 side. The movable guide 100 having a wedge-like shape is interposed between the inclined surface and the fixed guide 30. When the sliding faces are brought into a close contact with each other and the outer teeth 41 of each of the lock gears 40 are engaged with the inner teeth 21 gear plate 20, the gear plate 20 is locked from rotating (that is, reclining) . On the other hand, when unlocking the reclining, the center shaft 70 is rotated to release the engagement between the outer teeth 41 of the lock gears 40 and the inner teeth 21 of the gear plate 20.

In the embodiment 4, the contact face between the lock gear 40 and the movable guide 100 is inclined with respect to a movement direction of the lock gears 40.

Therefore, even when each of the lock gears 40 is disposed inner side, the lock gear 40 and the movable guide 100 can be separated away from each other without generating any friction therebetween.

Therefore, according to the embodiment 4, when unlocking, even when each of the movable guides 100 is pushed outward by the link plate 120, the lock gear is smoothly pulled inward. Therefore, the reclining device 200 can be constituted with a fewer component parts. Needless to say, the link plate 120 may be employed.

[0051] (Embodiment 5) Figs. 10 and 11 illustrate a reclining device 200, respectively, according to an embodiment 5. The reclining device 200 according to the embodiment 5 is identical to the embodiment 1 in many points.

Therefore, a point particularly different from that

in the embodiment 1 is described, and descriptions

on the identical points are omitted. As shown in Fig. 10, in the embodiment 5, each of the movable guides has outer teeth 102 capable of being engaged with the inner teeth 21 of the gear plate 20 at the outer end thereof. Therefore, according to the embodiment 5, when an overload is applied to the reclining device upon a collision of a vehicle and the like, a rotational load is transmitted from the gear plate to the lock gears 40, and the lock gears 40 functiOn to push each of the movable guides 100 between the fixed guide 30 and the same. Each of the movable guides 100 is formed in a shape that the width thereof gradually decreases from the outer end toward the inner end. Therefore, each of the movable guides 100 is pushed out outward of the base plate 10 as shown in Fig. 11. Therefore, the outer teeth 102 formed on the outer end of the respective movable guides 100 come closer to the inner teeth 21 of the gear plate and are engaged therewith. Thus, the movable guide 100 restrains the rotation of the gear plate along with the lock gear 40. That is, according to the embodiment 5, when an overload is applied to the reclining device 200 upon a collision of a vehicle or the like, the movable guides 100 restrain the gear plate 20 from rotating along with the lock gear 40.

Unintended inclination movement of the seat back can be prevented upon a collision of a vehicle. In the embodiment 5, the link plate 120 is not particularly

shown for the convenience of description. Needless

to say, the link plate 120 may be provided.

[0052] (Embodiment 6) Fig. 12 is an enlarged view in the vicinity of a movable guide 100 in a reclining device 200 according to an embodiment 6. The reclining device according to the embodiment 6 is identical to the embodiment 1 in many points. Therefore, a point particularly different from that in the embodiment

1 is described, and descriptions on the identical

points are omitted. In the embodiment 6, as shown in Fig. 12, the movable guide 100 is formed with a contact portion 103 that comes into close contact with a fixed guide 30 at the outer end side of a sliding surface of the movable guide 100 at the fixed guide side. And a step portion 104 for forming a gap between the fixed guide and the movable guide 100 is formed continuously with the contact portion 103.

With the arrangement, the movable guide 100 comes in close contact with the fixed guide 30 at the contact portion 103 only. Therefore, according to the embodiment 6, even when a little error is generated in the dimensions of the fixed guide 30, the movable guide 100 naturally comes into close contact with the fixed guide 30 at the outer end side thereof. Thus, the mechanical play in the front-rear direction of the seat back can be reliably prevented. In the embodiment 6, the link plate 120 is not particularly

shown for convenience of description. Needless to

say, the link plate 120 may be provided.

(0053] (Embodiment 7) Fig. 13 and Fig. 14 illustrate a reclining device 200 according to embodiment 7 and a part of a bracket 300 constituting a seat frame of a vehicle seat on which the reclining device 200 is mounted.

In the embodiment shown in Fig. 13, convex portions 11 are formed at four points in the rear face of the base plate 10 at the upper, lower, right and left side of the lock gears 40. The convex portions 1]. are inserted into holes 301 formed in the bracket 300 at four points. Then, the four points are arc-welded to form welded portions 302, thereby the convex portions 11 and the bracket 300 are integrated so as not be separated from each other. In the embodiment shown in Fig. 14, the base plate 10 is formed with flat portions in positions where the lock gears 40 and the movable guides 100 are positioned in the rear face. Two convex portions 11 are formed between the upper and lower lock gears 40. These convex portions 11 are inserted into the holes 301 formed at two points in the bracket 300. After that, the portions where the periphery of the convex portions 11 inserted into the holes 301 and the portions where the flat portions on the bracket 300 are laser-welded to form welded portions 302. Thus, the both members are integrated so as not to separate fromeachother. Particularly, by employing the laser welding, emboss-processed portions are formed in a small size on the base plate 10, and moreover, it is not necessary to form a large opening in the bracket 300. That is, plastic processing on the component parts is limited to the minimum. Therefore, a vehicle seat having a high strength can be provided.

[0054] (Embodiment 8) Figs. 15-18 illustrate a reclining device 200 according to an embodiment 8. The reclining device according to the embodiment 8 includes a base plate 10, a gear plate 20, a fixed guide 30, a lock gear 40, a cam 50, a spring 60, a center shaft 70, and a link plate 80. Each of the component elements will be described below.

[0055) The base plate 10 constitutes a base of the reclining device 200, and is fixed to either one of a seat cushion or a seat back of a vehicle seat.

The base plate 10 has to be strong enough to support the load of the seat back and the weight of an occupant.

Therefore, the base plate 10 is made of a steal plate inamannerofpressingorCuttiflg. Intheembodiment 8, the external shape of the base plate 10 is formed in a circular shape by pressing the steal plate, and thus the fixed guides 30 are formed. The fixed guides are attached to the seat cushion.

[0056] The gear plate 20 is rotatably assembled with the base plate 10 and is fixed to the other of the seat cushion or the seat back (not mounted with the base plate 10) on the vehicle seat. The gear plate 20 is formed with inner teeth 21 on the inner periphery at the side opposite to the side that is fixed to the seat back (or seat cushion) . The inner teeth 2]. can be engaged with outer teeth 41 of the lock gears 40. The gear plate 20 is engaged with the lock gear 40 to lock the inclination movement of the seat back in a front-rear direction thereof. The gear plate 20 has to be strong enough to support the load of the seat back and the weight of an occupant.

Therefore, the gear plate 20 is made of a steal plate janannerofpreSSiflgorCUtting. Intheembodilnent 8, the external shape of the gear plate 20 is formed in a circular shape by pressing a steal plate and inner teeth 21 are formed thereon. The gear plate 20 is fixed to the seat back.

[0057] A pair of the fixed guides 30 is integrally formed at two eccentric points in the base plate 10 for sandwiching and supporting the lock gear 40 respectively. The load of the seat back and the weight of an occupant are applied to the fixed guides 30. Therefore, the fixed guides 30 have to be strong enough to support the load. Therefore, the fixed guides 30 are formed of a steal plate in a manner of pressing or cutting. In the embodiment 8, the fixed guides 30 are formed by pressing the steal plate from the rear side thereof using dies.

[0058] In this invention, the mechanical strength of the fixed guides 30 have to be lower than that of the gear plate 20 and the lock gears 40. The reason of this is as described below. That is, when a large load is applied to the reclining device 200 (upon an emergency), the fixed guides 30 are pushed and deformed by the lock gears 40 and thereby the outer end portions 31 are brought into contact with the inner teeth 21 of the gear plate 20.

[0059] The outer end portions 31 of the fixed guides 30 are preferably disposed as close to the front end of the inner teeth 21 of the gear plate 20 as possible. With this arrangement, when the fixed guides 30 are deformed, the outer end portions 31 are further reliably engaged with inner teeth 21 of the gear plate 20.

[0060] Furthermore, the fixed guides 30 are preferably formed with a thickness that ensures the fixed guides 30 to be maintained in a close contact with the gear plate 20 when the base plate 10 and the gear plate 20 are assembled. With this arrangement, when the fixed guides 30 are deformed, the gear plate restricts the deformation of the fixed guides 30 in a thickness direction. Almost of the deformation amount of the fixed guides 30 are utilized for biting into the inner teeth 21 of the gear plate 20.

(0061] The side faces of the lock gears 40 are formed to be parallel to each other so as to slide between the fixed guides 30. The lock gears 40 are formed with outer teeth 41 on one edge connecting the side faces thereof, and are capable of being engaged with the inner teeth 21 of the gear plate 20. When the outer teeth 41 are engaged with the inner teeth 21 of the gear plate 20, the lock gears 40 primary bear the load from the gear plates 20. Therefore, the lock gears 40 have to be strong enough to bear such load. The lock gear 40 is preferably formed in such manner that, after forming a base metal by pressing or cutting a steal plate, the steal plate is subjected to quench hardening or forging. In the embodiment 8, the lock gears 40 are formed of a steal plate, and are pressed and subjected to quench hardening. The lock gears 40 are formed with projections 42 so as to be joined with the link plate 80.

[0062] The cam 50 is disposed in a substantially central area of the base plate 10 and a shaft 70 is inserted therethrough. The cam 50 rotates along with the shaft 70 to control the movement (sliding) of the lock gears 40. That is, when the cam 50 rotates, the lock gears 40 are engaged with or disengaged from the gear plate 20 to thereby lock or unlock the inclination movement of the seat back mounted with the reclining device 200 in a front-rear direction thereof. In the embodiment 8, the cam 50 is formed with a rectangular hole 52 that allows a rectangular-shaped portion 71 of the center shaft 70 to be inserted therethroUgh. Further, the cam 50 is formed with two projectionS 51 for allowing a link plate 80 to be connected therewith.

[00631 The springs 60 impart a rotational force to the cam 50 to keep a state that the lock gears 40 are engaged with the inner teeth 21 of the gear plate 20. In the embodiment 8, a spiral spring is employed for the springs 60. One end of the springs 60 is engaged with the cam 50, and the other end thereof is engage with an engagement projection formed on the base plate 10. The invention is not limited to the above arrangement. It may be arranged so that a spring 60 (not shown) is mounted on the center shaft to thereby impart the rotational force.

[0064) The center shaft 70 is inserted into a through hole formed in a central area of the base plate and the gear plate 20 respectively to thereby coaxially support the base plate 10 and the gear plate 20. An operation lever 72 is attached to the center shaft 70 as a separate member. When an occupant operates the operation lever 72 manually, the cam 50 and the link plate 80, through which the operation lever 72 is inserted, are rotated simultaneouslY between the base plate 10 and the gear plate 20.

Thereby, the lock gears 40 are engaged with or disengaged from the gear plate 20. In the embodiment 8, the center shaft 70 is made of a steel material in a manner of cutting the same. To be more precisely, the center shaft 70 is formed with the rectangular-shaped portion 71, which can be inserted through the rectangular hole 81 formed in the cam 50 and the link plate 80 in a substantially central area thereof. One end of the center shaft 70 is formed to mount to the operation lever 72; and the other thereof is formed with a serratiofl 73 to be connected with a link shaft (not shown) . The reclining devices are mounted, at the right and left both sides, at the joint portion of the vehicle seat. Therefore, the cam 50 of the reclining device 200, which is located at the left side of the seat, and the cam 50 of the reclining device 200, which is located at the right side of the seat, have to be rotated symmetrically via the link shaft.

[0065) When the cam 50 is rotated to disengage the lock gears 40 from the inner teeth 21 of the gear plate 20, the link plate 80 rotates along with the cam 50 to pull the lock gears 40 in an inner direction.

In the embodiment 8, the link plate 80 is formed with a rectangular hole 81, through which the rectangular-shaped portion 71 of the shaft is inserted, in the central position of a circular shaped thin plate. The link plate 80 is also formed with a pair of round holes 82 for allowing a pair of projectionS 51 of the cam 50 to be inserted therethroUgh. Furthermore, the link plate 80 is formed with a pair of elongated holes 83 for allowing a pair of projectiOns 42 of the lock gear 40 to be inserted therethrough.

[00663 The operation of the reclining device 200 according to the embodiment 8, which is arranged as described above, is described below with reference to Figs. 15-18.

[00671 In the reclining device 200 according to the embodiment 8, to lock the seat back to prevent the inclination movement in the front-rear direction, an occupant releases the operation lever 72 first.

When the operation lever 72 is released, the cam 50, to which a force is imparted in a clockwise direction in the figures, is rotated by the pair of springs 60 as shown in Fig. 15. The pair of lock gears 40 is pushed to slide outward in the base plate 10 along the fixed guides 30. The outer teeth 41 of the lock gears 40 engage with inner teeth 21 on the inner periphery of the gear plate 20. Thus, the seat back is locked and the inclination movement in the front-rear direction is prevented.

[0068] On the other hand, in the reclining device according to the embodiment 8, when unlocking the seat back to allow the inclination movement in the front-rear direction, the occupant pulls up (or pushes down) the operation lever 72. When the operation lever 72 is rotated, the center shaft 70, to which the operation lever 72 is attached, rotates in a counterclockwise direction as shown in Fig. 16.

The cam 50 and the link plate 80, through which the center shaft 70 is inserted, are also rotated simultaneouslY. When the cam 50 rotates, a gap is generated between the cam 50 and the lock gears 40.

When the outer edge of the elongated holes 83 of the link plate 80 comes into contact with the pair of projections 42 of the lock gears 40, thereby the lock gears 40 are smoothly pulled inward; and thus, the gap is eliminated. When the lock gears 40 are pulled inward, the seat back is allowed to perform an inclination movement in a front-rear direction thereof. The above-described a series of operations is carried out substantially simultaneously.

[00691 In the reclining device 200 according to the embodiment 8, when an overload is applied to the reclining device upon a collision of a vehicle or the like (at an emergency case), the lock gears 40 push the fixed guides 30 and the fixed guides 30 are deformed as shown in Fig. 18. The outer end portions 31 of the fixed guides 30 are caused to bite into the inner teeth 21 of the gear plate 20; and thereby the gear plate 20 is firmly fixed, and the seat back is prohibited from performing the inclination movement.

When an overload is applied to the reclining device upon a collision of a vehicle or the like, the fixed guides 30 are plastically deformed and the outer end portions 31 thereof bite into the inner teeth 21 of the gear plate 20. The vehicle seat can be reused by exchanging the reclining device 200 only.

[0070] (Embodiment 9) Fig. 19 illustrates a reclining device 200 according to an embodiment 9. Basic structure of the reclining device 200 according to the embodiment 9 is identical to that in the embodiment 1. In the embodiment 9, the mechanical strength of the component members is the identical to that in the embodiment 8. A point particularlY different from that in the embodiment 1 or embodiment 8 will be described, and descriptions on the identical points are omitted. The link plate 120 according to the embodiment 9 has a pair of cuts-off 125 in the outer periphery of the link plate 120. The cut-off 125 is located at the point of the outer periphery where comes into contact with the outer end portion 31 of the fixed guide 30 when the lock gear 40 is engaged with the inner teeth 21 of the gear plate 20 as shown in Fig. 19. When the fixed guide 30 is deformed, the deformation of the fixed guide 30 in a thickness direction thereof is allowed to go out from the cut-off 125 in the link plate 120 and to come into contact with the gear plate 20. Therefore, according to the embodiment 9, when an overload is applied to the reclining device 200 upon a collision of a vehicle or the like, a part of the deformed fixed guides 30 goes out from the cut-off 125 and engages with the gear plate 20. That is, the shifting direction of the material of the deformed fixed guides 30 can be desirably controlled. Therefore, the fixed guide 30 can be engaged with the gear plate 20 further effectively.

(0071] (Embodiment 10) Figs. 20 and 21 illustrate a reclining device 200, respectively, according to an embodiment 10.

The reclining device 200 according to the embodiment is identical to the embodiment 1 in many points.

Therefore, a point particularly different from that

in the embodiment 1 is described, and descriptiOnS

on the identical points are omitted. In the embodiment 10, in each of the upper and lower fixed guides 30, the inner edge portion is linearly formed as shown in Fig. 20. Between the upper and lower fixed guides 30, a guide block 32 shown in Figs. 21B and 21C is disposed respectively as shown in Fig. 21A.

Thus, the upper and lower fixed guides 30 are integrated with no gap. A protruding portion on the bottom face of the guide block 32 enters into an embossed hole forming a convex portion 1]. in the base plate 10. Thereby, the guide block 32 is precisely positioned and prevented from being displaced. When a load is applied to the reclining device 200 in which the base plate 10 includes two pair of fixed guides of the invention, the load is converged only on the two fixed guides 30 on a diagonal line in the four fixed guides 30. Since the fixed guides 30 are formed by pressing (emboss press) the base metal constituting the base plate 10, a thin portion is generated in an area where the bottom end portion of the fixed guide 30 is located. Compared to the other portion of the base plate 10, the thin portion is inferior in strength. When an extremely large load is applied to the reclining device 200, the base plate may be broken in the thin portion. Therefore, between the upper and lower fixed guides 30 the guide block 32 is disposed as the embodiment 10 to integrate the upper and lower fixed guides 30 with no gap.

Thereby, the load applied to the two fixed guides 80 located on one diagonal line can be shared by the other two fixed guides 30 located on the other diagonal line.

Even when a large load is applied to the reclining device 200, the base plate 10 can be prevented from being broken. Thus, the reclining device 200 having a high strength can be provided.

Brief Description of the drawings

[0072] Fig. 1A is a sectional view of a reclining device according to an embodiment 1 taken along a line B-B in Fig. lB. Fig. lB is a sectional view taken along a line A-A in Fig. 1A.

Fig. 2 illustrates the reclining device 200 in Fig. 1A showing an unlocked state.

Fig. 3 illustrates the reclining device 200 shown in Fig. 1A in which a link plate 120 is mounted.

Fig. 4 illustrates the reclining device 200 shown in Fig. 3 in which the lock is released.

Fig. 5 illustrates the reclining device 200 according to an embodiment 2 showing the inside thereof in which a gear plate 20 is taken out in an inner teeth 21 portion.

Fig. 6 illustrates the reclining device 200 according to an embodiment 3 showing the inside thereof in which a gear plate 20 is taken out in an inner teeth 21 portion.

Fig. 7 illustrates the reclining device 200 shown in Fig. 6 showing the inside thereof provided with a torsion spring 110 according to another embodiment.

Fig. 8 illustrates the reclining device 200 shown in Fig. 6 showing the inside thereof provided with a torsion spring 110 according to another embodiment.

Fig. 9 illustrates the reclining device 200 according to an embodiment 4 showing the inside thereof in which a gear plate 20 is taken out in an inner teeth 21 portion.

Fig. 10 illustrates the reclining device 200 according to an embodiment 5 showing the inside thereof in which a gear plate 20 is taken out in an inner teeth 21 portion.

Fig. 11 illustrates the reclining device 200 shown in Fig. 10 showing a state in which an overload is applied thereto.

Fig. 12 illustrates the reclining device 200 according to an embodiment 6 showing the enlarged vicinity of a movable guide 100.

Fig. 13 illustrates a part of a bracket 300 constituting a seat frame in the vehicle seat and the reclining device 200 according to an embodiment 7; the both members are integrated by means of an arc welding so as not be separated from each other.

Fig. 14 illustrates a part of a bracket 300 constituting a seat frame in the vehicle seat and the reclining device 200 according to an embodiment 7; the both members are integrated by means of an arc welding so as not be separated from each other.

Fig. iSA is a sectional view taken along a line D-Din Fig. according to the embodiment 8, which is locked not to be reclined; Fig. 15B is a sectional view taken along a line C-C in Fig. 18A.

Fig. 16 illustrates the reclining device 200 shown in Fig. 15 showing a state in which the lock of the reclining is released.

Fig. 17 illustrates the reclining device 200 shown in Fig. 15 showing an ordinary state in which a link plate 80 is removed therefrom.

Fig. 18 illustrates the reclining device 200 shown in Fig. 17, showing an emergency state that an overload is applied to the reclining device 200, and the fixed guides 30 are plastically deformed and the outer end portions 31 thereof are engaged with inner teeth 21 of a gear plate 20.

Fig. 19A illustrates a reclining device 200 according to an embodiment 9, illustrating the inside of the reclining device 200 to show the inner teeth 21 of the gear plate 20; Fig. 19B is a sectional view taken along a line E-E in Fig. 19A. Fig. 19C illustrates a state an overload is applied to the reclining device 200 shown in Fig. 19B and the material of the fixed guide 30 has shifted.

Fig. 20 illustrates the reclining device 200 according to an embodiment 10 showing the inside thereof in which a gear plate 20 is taken out in an inner teeth 21 portion.

Fig. 21A illustrates the reclining device 200 shown in Fig. 20 in which a guide block 32 shown in Fig. 21B and 21C is disposed between the upper and lower fixed guides 30 to integrate the upper and lower fixed guides 30 with no gap; Fig. 21B illustrates the bottom face of the guide block 32 shown in Fig. 21A; and Fig. 21C is a sectional view taken along a line F-F in Fig. 21B.

Explanation of reference numerals [0073] 10: base plate 11: Convex portion 20: gear plate 21: inner teeth 30: fixed guide 31: outer end portion 32: guide block 40: lock gear 41: outer teeth 42: projection 50: cam 51: projection 52: rectangular hole 60: spring 70: Center shaft 71: rectangular_shp portion 72: operation lever 73: serratjon 80: link plate 81: rectangular hole 82: round hole 83: elongated hole 100: movable guide 101: projection 102: outer teeth 103: contact portion 104: step portion 110: torsion spring 120: link plate 121: rectangular hole 122: round hole 123: generally sector-shaped hole 124: concave portion 125: cut-off 200: reclining device 300: bracket 301: hole 302: welded portion

Claims

Cia uns 1. A reclining device, comprising: a base plate fixed to either one of a seat cushion or a seat back; a gear plate having inner teeth, the gear plate being rotatably assembled with the base plate and fixed to the other one of the seat cushion or the seat back; two pairs of fixed guides formed on the base plate; a pair of lock gears each having outer teeth capable of being engaged with the inner teeth of the gear plate, each of the lock gears being disposed between the respective pair of fixed guides so as to slide along one of the fixed guides; a cam that controls the movement of the pair of lock gears to engage the pair of lock gears with the inner teeth of the gear plate; a pair of springs that imparts a rotational force to the cam to keep the lock gears being engaged with the inner teeth of the gear plate; and a center shaft capable of driving the cam to rotate to thereby disengage the pair of lock gears from the gear plate, wherein the mechanical strength of the fixed guides is set to be lower than that of the gear plate and the lock gears, when a large load is applied to the reclining device, the lock gears push the fixed guides to deform the same and cause the outer end portion of the fixed guides to come into contact with the inner teeth of the gear plate to thereby prohibit the inclination movement of the seat back.
2. The reclining device according to claim 1, wherein the fixed guides is disposed so that the outer end portion thereof is positioned close to the front end of the inner teeth of the gear plate, when the fixed guides are deformed, the outer end portion thereof bites into the inner teeth of the gear plate.
3. The reclining device according to claim 1 or 2, wherein the fixed guides are formed in a thickness such that, when the base plate and gear plates are assembled with each other, the fixed guides comes into substantially close contact with the gear plates, when the fixed guides are deformed, the gear plate restricts the deformation in a thickness direction thereof.
4. The reclining device according to claim 1 or 2, further comprising a link plate that rotates along with the cam to pull the lock gears inward when the cam is rotated to disengage the lock gears from the inner teeth of the gear plate, wherein the link plate includes a cut-off in an outer periphery at a point where, when the lock gears are engagedwith the inner teeth of the gear plate, comes into contact with the outer end portion of the fixed guides in the outer periphery of the link plate, when the fixed guides are deformed, the deformation in a thickness direction thereof is released from the cut-off of the link plate to allow the same to come into contact with the gear plate.