Patent Description:
Conventional seats for vehicles involve a seat which includes a reclining device for fixing a seatback or backrest at a certain tilt angle in such a manner that the seatback is tiltable to a seat cushion or seat base in a front-rear direction.

The reclining device includes a pair of reclining mechanisms or recliners arranged on both sides of the seat in a width direction of the seat, and a connecting rod extending in the width direction of the seat and coupled to the reclining mechanisms.

Each of the reclining mechanisms has a cam coaxially coupled to each of the opposite ends of the connecting rod and being rotatable together with the connecting rod. When the connecting rod receives a rotational manipulation force from the outside of the seat, the cam rotates together with the connecting rod in a predetermined direction to disconnect a locking plate arranged in the periphery of the cam from an internal gear, thereby achieving lock release.

The structure where each end of the connecting rod is coaxially coupled to the cam, as described above, requires a clearance between an inner surface of a through hole of the cam and an outer surface of the connecting rod. Specifically, a dimensional difference and distortion of a frame assembly (i.e., an assembly including: frames of the seatback and the seat cushions; and the reclining mechanisms attached to the frames) that are attributed to deviation and twisting in setting up the frame assembly may give unfavorable influence on operability of the reclining mechanisms and a lock load. It is necessary to provide the clearance to accommodate the unfavorable influence.

The conventional reclining device requiring the clearance between the cam and the connecting rod has drawbacks that the cam and the connecting rod interfere with each other due to bouncing or swaying of a vehicle body, or an impact from the outside, resulting in making an abnormal sound (hitting sound).

In this regard, the reclining device disclosed in <CIT> has a thin elastic ring interposed between the cam and the connecting rod to prevent an occurrence of an abnormal sound while permitting a clearance to exist between the cam and the connecting rod. In this manner, abnormal sound suppression is aimed.

However, in the structure having the thin elastic ring interposed between the cam and the connecting rod as described in <CIT>, the thin elastic ring determines relative positions of the cam and the connecting rod. For this reason, it is difficult to achieve effective prevention of abnormal sound while permitting the clearance to exist between the cam and the connecting rod. The reasons will be described below.

First, the elastic ring has a dimension restricted by a width of the clearance between the cam and the connecting rod. This makes it structurally difficult to increase the stiffness of the elastic ring by increasing the thickness of the elastic ring. Increasing the stiffness of the elastic ring for the prevention of abnormal sound under the dimensional restriction of the elastic ring leads to difficulty in inserting the elastic ring into the clearance between the cam and the connecting rod. This results in affecting the assembly of the reclining device. On the other hand, decreasing the stiffness of the elastic ring causes reduction in a holding force of the connecting rod, and thus an abnormal sound occurs even when the connecting rod only slightly shifts and comes into contact with the cam. From these perspectives, it is difficult to achieve effective prevention of abnormal sound while permitting the clearance to exist.

<CIT> discloses an alternative pair of reclining mechanisms with a connecting rod mounted to a bushing placed in these mechanisms and with said bushing driving a cam of these mechanisms.

The present invention has been achieved in view of the circumstances described above, and has an object of providing a reclining device that achieves effective prevention of abnormal sound while permitting a clearance to exist between a cam and a connecting rod.

A reclining device according to the present invention is a reclining device for holding a seatback to a seat cushion in a tiltable manner and fixing the seatback at a certain tilt angle. The reclining device includes: a pair of reclining mechanisms arranged on both sides of a seat in a width direction thereof, and each having an internal gear fixedly attached to a frame of one of the seat cushion and the seatback and a cam arranged in juxtaposition with the internal gear in a thickness direction of the internal gear; a connecting rod extending in the width direction of the seat, coaxially coupled to the cam of each of the reclining mechanisms, and being rotatable together with the cam; and a resin bush having a cylindrical shape formed with a fit hole to receive a fitting part formed on the connecting rod at a portion adjacent to each end of the connecting rod. The cam has a rod insertion hole for allowing the end of the connecting rod to be inserted therein. The internal gear has a bush insertion hole for allowing the resin bush to be inserted therein at a center position of the internal gear. The fitting part adjacent to the end of the connecting rod fits in the fit hole of the resin bush, and the end of the connecting rod protrudes outward of the resin bush. The resin bush is placed in the bush insertion hole in contact with an inner surface of the bush insertion hole of the internal gear to retain the connecting rod at such a position to the cam that a clearance exists between an inner surface of the rod insertion hole of the cam and an outer surface of the connecting rod. The inner surface of the bush insertion hole has an edge of the bush insertion hole.

Hereinafter, a preferable embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in <FIG>, a seat <NUM> according to the embodiment is a vehicle seat, and includes: a seat cushion <NUM> for supporting buttocks of a seated person; a seatback <NUM> arranged in the rear of the seat cushion <NUM> to support the back of the seated person and being tiltable to the seat cushion <NUM> in a front-rear direction X of the seat <NUM>; a sliding device <NUM> attached to a lower portion of the seat cushion <NUM>; and a reclining device <NUM>.

The sliding device <NUM> is configured to guide the seat cushion <NUM> slidably in the front-rear direction X of the seat <NUM>, and fixedly hold the seat cushion <NUM> at a certain position. Here, the seat according to the present invention may not indispensably include the sliding device <NUM>.

The reclining device <NUM> is configured to fixedly hold the seatback <NUM> at a certain tilt angle.

Specifically, as shown in <FIG>, the reclining device <NUM> according to the embodiment includes: a pair of reclining mechanism <NUM>; a connecting rod <NUM> connected to each of the reclining mechanisms <NUM>; and a pair of resin bushes <NUM> to each receive a fitting part 7c at a portion adjacent to corresponding one of ends 7b of the connecting rod <NUM>.

The reclining mechanisms <NUM> are respectively arranged on both sides of the seat <NUM> in a width direction Y thereof. Each of the reclining mechanisms <NUM> serves as a clutch to fixedly hold the seatback <NUM> at a certain tilt angle. The configuration of the reclining mechanism will be described in detail later.

As shown in <FIG>, <FIG>, and <FIG>, the reclining mechanism <NUM> in the embodiment includes: an internal gear <NUM> fixedly attached to a frame of one of the seat cushion <NUM> and the seatback <NUM>, that is, to a frame 3a of the seatback <NUM> (specifically, a side frame forming a side portion of the seatback <NUM>) in the embodiment in a fitting or welding manner; and a cam <NUM> arranged in juxtaposition with the internal gear <NUM> in a thickness direction of the internal gear (i.e., in an axial direction S of the connecting rod <NUM> shown in <FIG>).

In other words, in the reclining device according to the present invention, the reclining mechanism <NUM> may include at least the internal gear <NUM> and the cam <NUM>, and thus the remaining structural components may be appropriately changed.

As shown in <FIG>, <FIG>, and <FIG>, the cam <NUM> has a rod insertion hole 52a for allowing the end 7b of the connecting rod <NUM> to be inserted therein. The rod insertion hole 52a has a substantially elliptical shape, specifically, a circular shape inwardly narrowing from specific facing sides, in a cross section (in particular, see <FIG> and <FIG>).

As shown in <FIG>, and <FIG>, the internal gear <NUM> has a bush insertion hole <NUM> for allowing the resin bush <NUM> to be inserted therein through a through hole 3b (see <FIG>, and <FIG> to <FIG>) formed in the frame 3a at a center position of the internal gear <NUM>. The bush insertion hole <NUM> has a cross-sectionally circular shape.

As shown in <FIG>, the connecting rod <NUM> is a rod-shaped member extending in the width direction Y of the seat <NUM> and made of hard material, such as steel.

As shown in <FIG>, the connecting rod <NUM> specifically has a center part 7a having a cross-sectionally circular shape, the pair of ends 7b on both sides of the center part 7a, and the pair of fitting parts 7c.

Each end 7b has a shape approximate to a substantially elliptical shape conforming to the substantially elliptical shape of the rod insertion hole 52a (see <FIG> and <FIG>) of the cam <NUM>. Specifically, the end 7b has a pair of recesses 7e recessed radially inward at the radially opposite positions to face each other.

Owing to the insertion of the end 7b of the connecting rod <NUM> into the rod insertion hole 52a of the cam <NUM> that has the substantially elliptical shape, the connecting rod <NUM> is coaxially coupled to the cam <NUM> of each of the pair of reclining mechanisms <NUM> and can rotate together with the cam <NUM> (see <FIG>).

As shown in <FIG>, and <FIG>, a clearance <NUM> exists between an inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and an outer surface 7f of the end 7b of the connecting rod <NUM> in a state where the end 7b of the connecting rod <NUM> is placed in the rod insertion hole 52a of the cam <NUM>, in the same manner as a conventional art. This configuration can accommodate an unfavorable influence attributed to a dimensional difference and distortion of the frame assembly on the operability of the reclining mechanism <NUM> and a lock load.

As shown in <FIG>, the fitting part 7c of the connecting rod <NUM> fits to the resin bush <NUM> at a portion adjacent to the end 7b (i.e., adjacent to the end 7b at a position closer to the center part 7a or at a position between the center part 7a and the end 7b) on each side of the center part 7a. The fitting part 7c has a taper section 7d narrowing as advancing to the end 7b of the connecting rod <NUM>.

Specifically, the fitting part 7c has a cross-sectionally circular section <NUM> (see <FIG> and <FIG>) continuous to the center part 7a, a cross-sectionally substantially elliptical section <NUM> (see <FIG> and <FIG>) continuous to the end 7b, and the taper section 7d (see <FIG> and <FIG>) connecting the cross-sectionally circular section <NUM> and the cross-sectionally substantially elliptical section <NUM> to each other therebetween. The cross-sectionally substantially elliptical section <NUM> also has the recess 7e continuous from the end 7b (see <FIG>, <FIG>).

The taper section 7d has such a cross-sectional shape as to gradually change from a circular shape near the cross-sectionally circular section <NUM> to a substantially elliptical shape conforming to the shape of the end 7b as advancing to the end 7b.

The resin bush <NUM> is made of resin material, and includes a cylindrical body having a fit hole 8e, specifically, includes a main body 8a having a cylindrical shape, a flange 8b, and a pair of claws 8d as shown in <FIG>. The main body 8a, the flange 8b, and the pair of claws 8d are linearly assembled together in the axial direction S (see <FIG>) of the connecting rod <NUM>.

The resin bush <NUM> is mainly made of resin material, such as plastic, to prevent an occurrence of an abnormal sound between the connecting rod <NUM> and the cam <NUM>. The material for the resin bush <NUM> may be substituted by any material having elasticity, such as rubber (e.g., synthetic rubber) and elastomer. The material for the resin bush <NUM> may preferably have characteristics of low contact resistance between the internal gear <NUM> and the frame 3a, and less abrasion.

The resin bush <NUM> has the fit hole 8e to receive the fitting part 7c at a portion adjacent to the end 7b of the connecting rod <NUM>. The fit hole 8e axially penetrates the main body 8a and the flange 8b.

Therefore, as shown in <FIG> and <FIG>, the cylindrical main body 8a extends in the axial direction S of the connecting rod <NUM> to support the connecting rod <NUM> in contact with an entire circumference of the connecting rod in the state where the fitting part 7c of the connecting rod <NUM> fits in the fit hole 8e of the resin bush <NUM>.

The fit hole 8e of the resin bush <NUM> has a shape conforming to a contour of the fitting part 7c of the connecting rod <NUM>. Specifically, the fit hole 8e has a cross-sectionally circular hole section 8e1 (see <FIG> and <FIG>) conforming to the cross-sectionally circular section <NUM> of the fitting part 7c, a taper hole section 8e2 (see <FIG> and <FIG>) conforming to the taper section 7d, and a cross-sectionally substantially elliptical hole section 8e3 (see <FIG> and <FIG>) conforming to the cross-sectionally substantially elliptical section <NUM>.

The taper hole section 8e2 has a taper shape fittable onto the taper section 7d of the connecting rod <NUM> that also has a taper shape. Although a small gap is seen between the taper section 7d and an inner surface of the taper hole section 8e2 in <FIG> and <FIG>, the small gap may be excludable.

The flange 8b of the resin bush <NUM> has a circular plate shape extending radially outward from an end periphery edge (specifically, outer end periphery edge in the axial direction S in <FIG>) of the main body 8a. The flange 8b is contactable with the frame 3a (specifically, a surface of the frame 3a opposite to the internal gear <NUM>) of the seatback <NUM> that is fixedly attached to the internal gear <NUM> in the axial direction S of the connecting rod <NUM> in the state where the resin bush <NUM> is fitted to the fitting part 7c of the connecting rod <NUM> (see <FIG>, and <FIG> to <FIG>).

As shown in <FIG>, <FIG>, and <FIG>, the pair of claws 8d protrudes outward from a surface of the flange 8b opposite to the main body 8a and extends in the axial direction S of the connecting rod <NUM> to support the connecting rod <NUM> on both sides thereof.

As shown in <FIG>, the two claws 8d respectively have facing portions 8d1 facing each other, each facing portion having a shape (e.g., a recessing or protruding shape) fittable onto the cross-sectionally substantially elliptical section <NUM> of the fitting part 7c of the connecting rod <NUM>. Specifically, each of the facing portions 8d1 has a protruding shape fittable in the corresponding one of the pair of recesses 7e formed in the cross-sectionally substantially elliptical section <NUM> of the fitting part 7c.

Moreover, as shown in <FIG>, each of the claws 8d has an outer surface 8d2 opposite to the connecting rod <NUM>, the outer surface having a shape fittable in the bush insertion hole <NUM> of the internal gear <NUM>. Specifically, as shown in <FIG>, the outer surface 8d2 of each of the claws 8d curves in an arc shape so that the claws 8d are fittable in the bush insertion hole <NUM> (see <FIG>) having a cross-sectionally circular shape. In other words, the outer surface 8d2 having the arc shape is in surface contact with the inner surface of the bush insertion hole <NUM> having the cross-sectionally circular shape in the state where the claws 8d fit in the bush insertion hole <NUM>. Consequently, a stable fitting state is attainable.

In the reclining device <NUM> having the above-described configuration, first, the resin bush <NUM> is fitted to the fitting part 7c adjacent to the end 7b of the connecting rod <NUM> for coaxially coupling the end 7b of the connecting rod <NUM> to the reclining mechanism <NUM>, as shown in <FIG>, and <FIG>. At this time, the end 7b of the connecting rod <NUM> protrudes outward of the resin bush <NUM>.

Next, the end 7b of the connecting rod <NUM> and the pair of claws 8d of the resin bush <NUM> are inserted in the bush insertion hole <NUM> of the internal gear <NUM> through the through hole 3b of the frame 3a of the seatback <NUM>. Specifically, the pair of claws 8d is fitted in the bush insertion hole <NUM> so that the outer surface 8d2 of each of the claws 8d comes into contact with the inner surface and the edge of the bush insertion hole <NUM>. At this time, the resin bush <NUM> is placed (specifically, fitted) in the bush insertion hole <NUM> of the internal gear <NUM> to retain the connecting rod <NUM> at such a position to the cam <NUM> that the clearance <NUM> exists between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the end 7b of the connecting rod <NUM>. This allows the end 7b of the connecting rod <NUM> to fit in the bush insertion hole <NUM> of the internal gear <NUM> while permitting the clearance <NUM> to exist. In the state where the resin bush <NUM> is placed (fitted) in the bush insertion hole <NUM>, the outer surface 8d2 of each of the claws 8d may be in contact with at least a part of the inner surface of the bush insertion hole <NUM>, and may not be necessarily in contact with the edge of the inner surface of the bush insertion hole <NUM>.

In this configuration, the resin bush <NUM> is rotatable together with the connecting rod <NUM> and the cam <NUM> in the state where the pair of claws 8d fits in the bush insertion hole <NUM> of the internal gear <NUM>.

Hereinafter, a detailed configuration of the reclining mechanism <NUM> in the embodiment will be described. As described above, the reclining mechanism <NUM> may include at least the internal gear <NUM> and the cam <NUM> in the present invention. Hence, the remaining structural components may be appropriately changed.

The reclining mechanism <NUM> is provided between a frame 2a of the seat cushion <NUM> and the frame 3a of the seatback <NUM> (see <FIG>).

As shown in <FIG>, the reclining mechanism <NUM> includes a guide bracket <NUM>, the internal gear <NUM>, a spiral spring <NUM>, the cam <NUM>, four locking plates 60A to 60D, and an attachment ring <NUM>.

As shown in <FIG> and <FIG>, the guide bracket <NUM> is fixed around the rear of the frame 2a (specifically, a side frame) of the seat cushion <NUM>. The internal gear <NUM> is fixed around a lower portion of the frame 3a (specifically, a side frame) of the seatback <NUM>.

In an arrangement of the frame 2a of the seat cushion <NUM> inside the frame 3a of the seatback <NUM> as shown in <FIG>, the internal gear <NUM> may be fixedly attached to the frame 2a of the seat cushion <NUM>, and the guide bracket <NUM> may be fixedly attached to the frame 3a of the seatback <NUM>.

As shown in <FIG>, the guide bracket <NUM> has a disc shape, and has an arrangement hole <NUM> penetrating therethrough at a center thereof for arrangement of the spiral spring <NUM> therein. An inner surface of the arrangement hole <NUM> is formed with an engagement groove 22a. The engagement groove 22a is engaged with an outer end <NUM> of the spiral spring <NUM>.

The internal gear <NUM> has a circular shape in a plan view and further has a cross-sectionally substantially recess shape. The internal gear includes a recess section <NUM> having an inner surface formed with inner teeth <NUM>. The recess section <NUM> faces an inner surface 20a (see <FIG>) of the guide bracket <NUM>. The internal gear <NUM> is coupled to, for example, the frame 3a of the seatback <NUM> via a connection protrusion <NUM> protruding in a right depth direction on the paper of <FIG>.

The guide bracket <NUM> and the internal gear <NUM> are retained by the attachment ring <NUM> at such positions that the guide bracket <NUM> faces the recess section <NUM> of the internal gear <NUM> and an end surface <NUM> a1 of a peripheral wall 31a of the recess section <NUM> comes into contact with a surface of the guide bracket <NUM>.

The attachment ring <NUM> has an annular bottom plate <NUM> having an annular shape with a predetermined width in a substantially circle, and an annular side plate <NUM> extending in a direction substantially perpendicularly intersecting the outer edge of the annular bottom plate <NUM>, that is, extending along an outer surface <NUM> a2 of the peripheral wall 31a of the internal gear <NUM>. In other words, the attachment ring <NUM> has a substantially L-shape defined by the annular bottom plate <NUM> and the annular side plate <NUM> in a radial cross-section.

In the embodiment, the attachment ring <NUM> covers the guide bracket <NUM> and the internal gear <NUM> in such a manner that an end edge 72a of the annular side plate <NUM> extends over the outer surface 31a2 of the peripheral wall 31a of the internal gear <NUM> to reach an outer surface 21b of the guide bracket located beyond the outer surface 31a2 (on the left front side of paper of <FIG>) in a state where the guide bracket <NUM> and the recess section <NUM> of the internal gear <NUM> face each other to define an inner space therebetween for accommodating the spiral spring <NUM>, the cam <NUM>, and the lock mechanism including the locking plates 60A to 60D therein. In this assembling manner, a central protrusion of the internal gear <NUM> is exposed outward farther than an inner circle of the annular bottom plate <NUM> (exposed in the right depth direction on the paper of <FIG>). After the attachment of the attachment ring <NUM> in this way, a portion of the annular side plate <NUM> that faces the outer surface 21b of the guide bracket <NUM> is fixedly welded to the outer surface 21b. Hence, the guide bracket <NUM> and the internal gear <NUM> rotate relative to each other, when the seatback <NUM> is rotated relative to the seat cushion <NUM> in a state where the guide bracket <NUM> is fixedly attached to, for example, the frame 2a of the seat cushion <NUM> and the connection protrusion <NUM> of the internal gear <NUM> is fixedly attached to, for example, the frame 3a of the seatback <NUM>. The attachment ring <NUM> rotates together with the guide bracket <NUM> relative to the internal gear <NUM>. The annular side plate <NUM> of the attachment ring <NUM> restricts a radial shift of the internal gear <NUM>. The annular bottom plate <NUM> of the attachment ring restricts an axial shift of the internal gear <NUM>.

The cam <NUM> is a member for reciprocally moving the locking plates 60A to 60D in a radial direction of the cam <NUM>. The cam <NUM> is provided with four engaging protrusions <NUM>, <NUM> corresponding to the four locking plates 60A to 60D at equal intervals in a circumferential direction, each engaging protrusion having a horn-like shape extending in a substantially arc. A main body <NUM> of the cam <NUM>, from which the engaging protrusions <NUM>, 51are excluded, is provided with four bulges 52b, 52b each bulging outward to have a larger outer diameter at a predetermined angle from a base part of each of the engaging protrusions <NUM>, <NUM>. The cam <NUM> is integrally fixed to a surface of a spacer <NUM>, and has the rod insertion hole 52a penetrating the center of the cam <NUM> to receive the end 7b of the connecting rod <NUM> inserted therein. When a manipulation member (not shown) attached to the end 7b of the connecting rod <NUM> is used to rotate the connecting rod <NUM> forward or backward, the cam <NUM> rotates in the same direction by following the connecting rod.

The cam <NUM> has a first shaft <NUM> protruding from a periphery of the rod insertion hole 52a toward the guide bracket <NUM> on a surface facing the guide bracket <NUM>. The first shaft <NUM> has an outer diameter smaller than an inner diameter of the spiral spring <NUM>, and the first shaft <NUM> is formed with an engagement slit 53a notched from an outer surface of the shaft toward a center thereof. The spiral spring <NUM> is arranged to surround the first shaft <NUM>, and has an inner end <NUM> engageable with the engagement slit 53a of the first shaft <NUM> (see <FIG>) so as to be placed in the arrangement hole <NUM> of the guide bracket <NUM> together with the first shaft <NUM>. The spiral spring <NUM> urges the cam <NUM> in one rotational direction due to the engagement of the outer end <NUM> with the engagement groove 22a on the inner surface of the arrangement hole <NUM> of the guide bracket <NUM>.

The internal gear <NUM> is provided with a second shaft <NUM> protruding toward the cam <NUM> at the center of the internal gear. The second shaft <NUM> is inserted in a bearing hole (not shown) formed in the cam <NUM> to rotatably support the cam <NUM>.

The four locking plates 60A to 60D are used in the embodiment. The four locking plates 60A to 60D are respectively arranged to meet the four engaging protrusions <NUM>, <NUM> each having a horn-like shape in the cam <NUM>. Each of the locking plates 60A to 60D is slidable in a radial direction of the guide bracket <NUM> along a guide groove (not shown) formed in the guide bracket <NUM> and extending in the radial direction thereof.

Concerning the locking plates 60A to 60D and the cam <NUM>, the locking plates 60A to 60D are urged radially outward in response to a one-directional rotation of the cam <NUM> attributed to the elasticity of the spiral spring <NUM>, and the locking plates 60A to 60D shift toward the center in response to a reverse-directional rotation of the cam <NUM> by the connecting rod <NUM>. Each of the locking plates 60A to 60D has a substantially rectangular shape in a plan view. The locking plates 60A to 60D respectively have engaged grooves <NUM>, <NUM> each notched in a substantially are from an inner surface of the corresponding plate. When the cam <NUM> rotates in a clockwise direction, the engaging protrusions <NUM>, <NUM> engage with the corresponding engaged grooves <NUM>, <NUM> to pull the locking plates 60A to 60D toward the center of the cam <NUM>. When the cam <NUM> is urged by the spiral spring <NUM> and rotates in a counter-clockwise direction, the engaging protrusions <NUM>, <NUM> and the bulges 52b, 52b press the locking plates 60A to 60D radially outward of the cam <NUM>. The locking plates 60A to 60D have outer surfaces respectively formed with outer teeth <NUM>, <NUM> to mesh with the inner teeth <NUM> of the internal gear <NUM> when the plates are pressed radially outward, thereby locking the guide bracket <NUM> and the internal gear <NUM> irrotationally relative to each other. This achieves fixed holding of the seatback <NUM> at a certain tilt angle.

As shown in <FIG>, the reclining device <NUM> includes: the pair of reclining mechanisms <NUM> arranged on both sides of the seat <NUM> in the width direction Y thereof, and each having the internal gear <NUM> fixedly attached to the frame of one of the seat cushion <NUM> and the seatback <NUM> (to the frame 3a of the seatback <NUM> in the embodiment), and the cam <NUM> arranged in juxtaposition with the internal gear <NUM> in the thickness direction (i.e., width direction Y) of the internal gear; and the connecting rod <NUM> extending in the width direction Y of the seat <NUM>, coaxially coupled to the cam <NUM> of each of the reclining mechanisms <NUM>, and being rotatable together with the cam <NUM>.

The reclining device <NUM> according to the embodiment further includes the resin bush <NUM> having a cylindrical shape formed with the fit hole 8e to receive the fitting part 7c at a portion adjacent to each end 7b of the connecting rod <NUM>.

As shown in <FIG>, the cam <NUM> has the rod insertion hole 52a for allowing the end 7b of the connecting rod <NUM> to be inserted therein. The internal gear <NUM> has the bush insertion hole <NUM> for allowing the resin bush <NUM> to be inserted therein at the center position of the internal gear <NUM>.

As shown in <FIG>, and <FIG>, the fitting part 7c adjacent to the end 7b of the connecting rod <NUM> fits in the fit hole 8e of the resin bush <NUM>, and the end 7b of the connecting rod <NUM> protrudes outward of the resin bush <NUM>. The resin bush <NUM> is placed in the bush insertion hole <NUM> in contact with the inner surface of the bush insertion hole <NUM> of the internal gear <NUM> to retain the connecting rod <NUM> at such a position to the cam <NUM> that the clearance <NUM> exists between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the connecting rod <NUM>.

According to this configuration, the resin bush <NUM> is placed in the bush insertion hole <NUM> in contact with the inner surface of the bush insertion hole <NUM> of the internal gear <NUM> to retain the connecting rod <NUM> at such a position to the cam <NUM> that the clearance <NUM> exists between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the connecting rod <NUM>. In this manner, the resin bush <NUM> restricts the shift of the connecting rod <NUM> relative to the cam <NUM> in the radial direction of the cam <NUM>, and thus can prevent an occurrence of a contact sound between the cam <NUM> and the connecting rod <NUM>. This results in achieving effective prevention of abnormal sound while permitting the clearance <NUM> to exist between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the connecting rod <NUM>.

Besides, the resin bush <NUM> is not designed to determine relative positions of the cam <NUM> and the connecting rod <NUM> by intervening therebetween, but is designed to retain the connecting rod <NUM> at a specific position in a state of being placed in the bush insertion hole <NUM> of the internal gear <NUM>. Therefore, the resin bush <NUM> receives no dimensional restriction due to the clearance <NUM> between the cam <NUM> and the connecting rod <NUM> and no stiffness restriction based on such dimensional restriction. In this respect, the resin bush <NUM> can be set to a dimension and stiffness leading to less abrasion than those of the elastic ring of the conventional art (structure described in Patent Literature <NUM>).

(<NUM>) In the reclining device <NUM> according to the embodiment, the fit hole 8e of the resin bush <NUM> has a shape conforming to the contour of the fitting part 7c of the connecting rod <NUM>. Specifically, as shown in <FIG> and <FIG>, the fit hole 8e has the cross-sectionally circular hole section 8e1, the taper hole section 8e2, and the cross-sectionally substantially elliptical hole section 8e3.

According to this configuration, a work of attaching the resin bush <NUM> to the fitting part 7c at a portion of the connecting rod <NUM> adjacent to the end 7b is completed only by fitting the fitting part 7c adjacent to the end 7b of the connecting rod <NUM> in the fit hole 8e of the resin bush <NUM>. Thus the work has good workability. Furthermore, a simple configuration of the connecting rod <NUM> and the resin bush <NUM> in combination succeeds in preventing the resin bush <NUM> from axially coming off the internal gear <NUM> and further preventing the resin bush <NUM> from falling off the connecting rod <NUM>.

(<NUM>) In the reclining device <NUM> according to the embodiment, as shown in <FIG> and <FIG>, the resin bush <NUM> has the flange 8b coming into contact with the frame 3a of the seatback <NUM>, which is fixedly attached to the internal gear <NUM>, in the axial direction S of the connecting rod <NUM>.

According to this configuration, the flange 8b of the resin bush <NUM> can restrict the shift of the resin bush <NUM> in the axial direction S by coming into contact with the frame 3a of the seatback <NUM> in the axial direction S of the connecting rod <NUM>.

Moreover, the flange 8b can prevent an unacceptable matter from entering the reclining mechanism <NUM> through the through hole 3b by closing a gap between the resin bush <NUM> and an inner surface of the through hole 3b of the frame 3a.

(<NUM>) In the reclining device <NUM> according to the embodiment, the resin bush <NUM> has the main body 8a extending in the axial direction S of the connecting rod <NUM> and having a cylindrical shape to support the connecting rod <NUM> in contact with an entire circumference of the connecting rod.

According to this configuration, the cylindrical main body 8a of the resin bush <NUM> supports the connecting rod <NUM> in contact with the entire circumference of the connecting rod, and therefore can further restrict the shit of the connecting rod <NUM> relative to the cam <NUM> in the radial direction thereof. As a result, the effect of abnormal sound occurrence prevention is improved.

(<NUM>) In the reclining device <NUM> according to the embodiment, as shown in <FIG>, the fitting part 7c of the connecting rod <NUM> has the taper section 7d narrowing as advancing to the end 7b of the connecting rod <NUM>. As shown in <FIG> and <FIG>, the fit hole 8e of the resin bush <NUM> has the taper hole section 8e2 fittable to the taper section 7d of the connecting rod <NUM>.

According to this configuration, the taper section 7d formed at the fitting part 7c adjacent to the end 7b of the connecting rod <NUM> fits to the taper hole section 8e2 of the fit hole 8e of the resin bush <NUM> to restrict the shift of the resin bush <NUM> in the axial direction. Furthermore, a simple configuration of the connecting rod <NUM> and the resin bush <NUM> in combination succeeds in preventing the resin bush <NUM> from axially coming off the internal gear <NUM> and further preventing the resin bush <NUM> from falling off the connecting rod <NUM> without increasing the number of components.

(<NUM>) In the reclining device <NUM> according to the embodiment, as shown in <FIG>, <FIG>, and <FIG>, the resin bush <NUM> has the pair of claws 8d extending in the axial direction S of the connecting rod <NUM> to support the connecting rod <NUM> on both sides thereof.

According to this configuration, the claws 8d of the resin bush <NUM> support the connecting rod <NUM> on both sides thereof, and therefore can further restrict the shift of the connecting rod <NUM> relative to the cam <NUM> in the radial direction. As a result, the effect of abnormal sound occurrence prevention is improved.

(<NUM>) In the reclining device <NUM> according to the embodiment, as shown in <FIG>, each of the facing portions 8d1 of the claws 8d facing each other has a shape fittable onto the fitting part 7c of the connecting rod <NUM>. Specifically, each of the facing portions 8d1 has a protruding shape fittable in the corresponding recess 7e in the cross-sectionally substantially elliptical section <NUM> of the fitting part 7c.

According to this configuration, each of the facing portions 8d1 of the claws 8d of the resin bush <NUM> that face each other fit to the fitting part 7c adjacent to the end 7b of the connecting rod <NUM>, and therefore can further restrict the shift of the connecting rod <NUM> relative to the cam <NUM> in the radial direction. As a result, the effect of abnormal sound occurrence prevention is improved.

(<NUM>) In the reclining device <NUM> according to the embodiment, as shown in <FIG> and <FIG>, each of the claws 8d has the outer surface 8d2 opposite to the connecting rod <NUM>. The outer surface 8d2 of each of the two claws 8d has a shape fittable in the bush insertion hole <NUM> of the internal gear <NUM>. In other words, the outer surface 8d2 of each claw 8d has an arc shape fittable in the bush insertion hole <NUM> having the cross-sectionally circular shape.

According to this configuration, the pair of claws 8d of the resin bush <NUM> can more effectively support the connecting rod <NUM> on both sides thereof owing to fitting of the pair of claws 8d in the bush insertion hole <NUM> of the internal gear <NUM>. This enables further restriction of the shift of the connecting rod <NUM> relative to the cam <NUM> in the radial direction. In addition, the mere fitting of the pair of claws 8d in the bush insertion hole <NUM> facilitates determination on the positions of the resin bush <NUM> and the connecting rod <NUM>, resulting in improvement of the workability in the assembly of the reclining device <NUM>.

(<NUM>) As shown in <FIG>, the seat <NUM> according to the embodiment includes: the seat cushion <NUM>; the seatback <NUM> arranged in the rear of the seat cushion <NUM> and being tiltable in the front-rear direction X of the seat <NUM>; and the reclining device <NUM> having the above-described configuration for fixedly holding the seatback <NUM> at a certain tilt angle.

The seat <NUM> includes the reclining device <NUM> having the configuration where the resin bush <NUM> is placed in the bush insertion hole <NUM> in contact with the inner surface of the bush insertion hole <NUM> of the internal gear <NUM> to retain the connecting rod <NUM> in the state where the clearance <NUM> exists between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the connecting rod <NUM>. In this manner, the resin bush <NUM> restricts the shift of the connecting rod <NUM> relative to the cam <NUM> in the radial direction of the cam <NUM>. This results in achieving effective prevention of abnormal sound while permitting the clearance <NUM> to exist between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the connecting rod <NUM>.

As shown in <FIG> and <FIG>, the main body 8a of the resin bush <NUM> in the embodiment has such a length as to be fittable to the entirety of the fitting part 7c of the connecting rod <NUM>, i.e., to be fittable to the cross-sectionally circular section <NUM> and the taper section 7d in addition to the cross-sectionally substantially elliptical section <NUM>. However, in the present invention, the length of the main body 8a of the resin bush <NUM> is not particularly limited.

Therefore, in a modification of the present invention as shown in <FIG>, the length of a main body 8a of a resin bush <NUM> may be changed to be fittable only to a cross-sectionally substantially elliptical section <NUM>.

In the modification shown in <FIG>, downsizing of the resin bush <NUM> is attainable by decreasing the length of the main body 8a.

Even in the modification shown in <FIG>, the cross-sectionally substantially elliptical section <NUM> (i.e., the section having the recess 7e shown in <FIG>) of the connecting rod <NUM> can restrict the shift of the connecting rod <NUM> relative to the cam <NUM> in a radial direction thereof by fitting in the fit hole 8e (specifically, the cross-sectionally substantially elliptical hole section 8e3 as shown in <FIG>) of the main body 8a of the resin bush <NUM> and fitting to the protruding facing portions 8d1 of the pair of claws 8d. As a result, the effect of abnormal sound occurrence prevention is improved.

In the modification, as shown in <FIG>, although the resin bush <NUM> is not fitted to the taper section 7d of the connecting rod <NUM>, the taper section 7d is arranged in adjacent to the attachment position of the resin bush <NUM>. This arrangement makes it possible to prevent the resin bush <NUM> from deviating in the axial direction and coming off (specifically, coming off the through hole 3b of the frame 3a and coming off the bush insertion hole <NUM> of the internal gear <NUM>).

The resin bush <NUM> in the modification has a pair of flat surfaces facing each other on a circumference of the main body 8a, as shown in <FIG>, <FIG>. Thus, a rotation angle of each of the resin bush <NUM> and the connecting rod <NUM> is easily adjustable by using a tool.

In another modification of the present invention as shown in <FIG>, a resin bush <NUM> may be configured to exclude a main body 8a and have an engagement part 8f engageable with a frame 3a.

The engagement part 8f is configured to be engageable with the frame 3a of the seatback <NUM> that is fixedly attached to the internal gear <NUM>, for example, has a claw engageable with an edge of the through hole 3b of the frame 3a. The engagement part 8f protrudes radially outward of the resin bush <NUM> from an outer surface 8d2 of each of a pair of claws 8d.

In the modification in <FIG>, the engagement part 8f of the resin bush <NUM> engages with the frame 3a (specifically, the edge of the through hole 3b) of the seatback <NUM> that is fixedly attached to the internal gear <NUM>. This can prevent the resin bush <NUM> from coming off the frame 3a. Moreover, the resin bush <NUM> is firmly fixed by both the frame 3a and the internal gear <NUM>. The resin bush <NUM> therefore can restrict the shift of the connecting rod <NUM> relative to the cam <NUM> in the radial direction of the cam <NUM>. As a result, the effect of abnormal sound occurrence prevention is improved.

In a case where the internal gear <NUM> is fixedly attached to the frame 2a of the seat cushion <NUM>, the engagement part 8f may engage with the frame 2a of the seat cushion <NUM>.

In the modification shown in <FIG>, each of the pair of claws 8d of the resin bush <NUM> has an outer surface 8d2 opposite to the connecting rod <NUM>. The outer surface 8d2 has a taper shape slanting to the center of the bush insertion hole <NUM> as advancing to a leading end of the claw 8d to come into contact with the edge of the bush insertion hole <NUM> of the internal gear <NUM>. The edge falls within the inner surface of the bush insertion hole <NUM>. In this configuration, the pair of claws 8d of the resin bush <NUM> is placed in the bush insertion hole <NUM> in contact with the edge of the bush insertion hole <NUM>, and thus can retain the connecting rod <NUM> at such a position to the cam <NUM> that the clearance <NUM> exists between the inner surface 52a1 of the rod insertion hole 52a of the cam <NUM> and the outer surface 7f of the connecting rod <NUM>.

According to this configuration, the outer surface 8d2 having the taper shape in each of the claws 8d of the resin bush <NUM> comes into contact with the edge of the bush insertion hole <NUM> of the internal gear <NUM>, thereby succeeding in reliably maintaining the contact state between the resin bush <NUM> and the internal gear <NUM>. Moreover, this configuration can accommodate a dimensional difference in one of the bush insertion hole <NUM> and the pair of claws 8d, or both the insertion hole and the claws.

In the modification shown in <FIG>, downsizing of the resin bush <NUM> is attainable by excluding the main body 8a.

Furthermore, as shown in <FIG>, although the resin bush <NUM> is not fitted to the taper section 7d of the connecting rod <NUM>, the taper section 7d is arranged in adjacent to the attachment position of the resin bush <NUM>. This arrangement makes it possible to prevent the resin bush <NUM> from deviating in the axial direction and coming off (specifically, coming off the through hole 3b of the frame 3a and coming off the bush insertion hole <NUM> of the internal gear <NUM>).

The embodiment is summarized in the following manner.

A reclining device according to the embodiment is a reclining device for holding a seatback to a seat cushion in a tiltable manner and fixing the seatback at a fixed tilt angle. The reclining device includes: a pair of reclining mechanisms arranged on both sides of a seat in a width direction thereof, and each having an internal gear fixedly attached to a frame of one of the seat cushion and the seatback and a cam arranged in juxtaposition with the internal gear in a thickness direction of the internal gear; a connecting rod extending in the width direction of the seat, coaxially coupled to the cam of each of the reclining mechanisms, and being rotatable together with the cam; and a resin bush having a cylindrical shape formed with a fit hole to receive a fitting part formed on the connecting rod at a portion adjacent to each end of the connecting rod. The cam has a rod insertion hole for allowing the end of the connecting rod to be inserted therein. The internal gear has a bush insertion hole for allowing the resin bush to be inserted therein at a center position of the internal gear. The fitting part adjacent to the end of the connecting rod fits in the fit hole of the resin bush, and the end of the connecting rod protrudes outward of the resin bush. The resin bush is placed in the bush insertion hole in contact with an inner surface of the bush insertion hole of the internal gear to retain the connecting rod at such a position to the cam that a clearance exists between an inner surface of the rod insertion hole of the cam and an outer surface of the connecting rod. The inner surface of the bush insertion hole has an edge of the bush insertion hole.

According this configuration, the resin bush is placed in the bush insertion hole in contact with the inner surface of the bush insertion hole of the internal gear to retain the connecting rod at such a position to the cam that the clearance exists between the inner surface of the rod insertion hole of the cam and the outer surface of the connecting rod. In this manner, the resin bush restricts the shift of the connecting rod relative to the cam in the radial direction of the cam, and thus can prevent an occurrence of a contact sound between the cam and the connecting rod. This results in achieving effective prevention of abnormal sound while permitting the clearance to exist between the inner surface of the rod insertion hole of the cam and the outer surface of the connecting rod.

In the reclining device, the fit hole of the resin bush preferably has a shape conforming to a contour of the fitting part of the connecting rod.

According to this configuration, a work of attaching the resin bush to the connecting rod is completed only by fitting the fitting part adjacent to the end of the connecting rod in the fit hole of the resin bush. Thus, the work has good workability. Furthermore, a simple configuration of the connecting rod and the resin bush in combination succeeds in preventing the resin bush from axially coming off the internal gear and further preventing the resin bush from falling off the connecting rod.

In the reclining device, the resin bush preferably has a flange coming into contact with the frame of the one of the seat cushion and the seatback that is fixedly attached to the internal gear in an axial direction of the connecting rod.

According to this configuration, the flange of the resin bush can restrict the shift of the resin bush in the axial direction of the connecting rod by coming into contact with the frame of the one of the seat cushion and the seatback in the axial direction.

In the reclining device, the resin bush preferably has a main body extending in the axial direction of the connecting rod and having a cylindrical shape to support the connecting rod in contact with an entire circumference of the connecting rod.

According to this configuration, the cylindrical main body of the resin bush supports the connecting rod in contact with the entire circumference of the connecting rod, and therefore can further restrict the shift of the connecting rod relative to the cam in the radial direction thereof. As a result, the effect of abnormal sound occurrence prevention is improved.

In the reclining device, the fitting part of the connecting rod preferably has a taper section narrowing as advancing to the end of the connecting rod, and the fit hole of the resin bush preferably has a taper hole section to fit to the taper section of the connecting rod.

According to this configuration, the taper section formed at the fitting part adjacent to the end of the connecting rod fits to the taper hole section of the fit hole of the resin bush to restrict the shift of the resin bush in the axial direction. Furthermore, a simple configuration of the connecting rod and the resin bush in combination succeeds in preventing the resin bush from axially coming off the internal gear and further preventing the resin bush from falling off the connecting rod without increasing the number of components.

In the reclining device, the resin bush preferably has a pair of claws extending in the axial direction of the connecting rod to support the connecting rod on both sides thereof.

According to this configuration, the claws of the resin bush support the connecting rod on both sides thereof, and therefore can further restrict the shift of the connecting rod relative to the cam in the radial direction. As a result, the effect of abnormal sound occurrence prevention is improved.

In the reclining device, preferably, the claws respectively have portions facing each other, and each having a shape fittable onto the fitting part of the connecting rod.

According to this configuration, each of the facing portions of the claws of the resin bush that face each other fit to the fitting part adjacent to the end of the connecting rod, and therefore can further restrict the shift of the connecting rod relative to the cam in the radial direction. As a result, the effect of abnormal sound occurrence prevention is improved.

In the reclining device, each of the claws preferably has an outer surface opposite to the connecting rod, and the outer surface preferably has a shape fittable in the bush insertion hole of the internal gear.

According to this configuration, the claws of the resin bush more effectively support the connecting rod on both sides thereof owing to the fitting of the pair of claws in the bush insertion hole of the internal gear. This enables further restriction of the shift of the connecting rod relative to the cam in the radial direction. In addition, the mere fitting of the pair of claws in the bush insertion hole facilitates determination on the positions of the resin bush and the connecting rod, resulting in improvement of the workability in the assembly of the reclining device.

In the reclining device, each of the claws preferably has an outer surface opposite to the connecting rod, and the outer surface preferably has a taper shape slanting to a center of the bush insertion hole as advancing to a leading end of the claw to come into contact with an edge of the bush insertion hole of the internal gear.

According to this configuration, the outer surface having the taper shape in each of the claws of the resin bush comes into contact with the edge of the bush insertion hole of the internal gear, thereby succeeding in reliably maintaining the contact state between the resin bush and the internal gear. Moreover, this configuration can accommodate a dimensional difference in one of the bush insertion hole of the claws, or both the insertion hole and the claws.

In the reclining device, the resin bush further preferably has an engagement part engageable with the frame of the one of the seat cushion and the seatback that is fixedly attached with the internal gear.

According to this configuration, the engagement part of the resin bush can prevent the resin bush from coming off the frame of one of the seat cushion and the seatback that is fixedly connected to the internal gear by engaging with the frame. Moreover, the resin bush is firmly fixed by both the frame and the internal gear. The resin bush therefore can restrict the shift of the connecting rod relative to the cam in the radial direction of the cam. As a result, the effect of abnormal sound occurrence prevention is improved.

A seat according to the embodiment includes: a seat cushion: a seatback located in the rear of the seat cushion and being tiltable in a front-rear direction of the seat; and the reclining device to fixedly hold the seatback at a certain tilt angle.

The seat includes the reclining device having the configuration where the resin bush is placed in the bush insertion hole in contact with the inner surface of the bush insertion hole of the internal gear to retain the connecting rod in the state where the clearance exists between the inner surface of the rod insertion hole of the cam and the outer surface of the connecting rod. In this manner, the resin bush restricts the shift of the connecting rod relative to the cam in the radial direction of the cam. This results in achieving effective prevention of abnormal sound while permitting the clearance to exist between the inner surface of the rod insertion hole of the cam and the outer surface of the connecting rod.

Claim 1:
A reclining device (<NUM>) for holding a seatback to a seat cushion in a tiltable manner and fixing the seatback at a certain tilt angle, the reclining device comprising:
a pair of reclining mechanisms (<NUM>) to be arranged on both sides of a seat in a width direction thereof and each having an internal gear (<NUM>) to be a fixedly attached to a frame of one of the seat cushion and the seatback and a cam (<NUM>) arranged in juxtaposition with the internal gear in a thickness direction of the internal gear;
a connecting rod (<NUM>) extending in the width direction of the seat, coaxially coupled to the cam of each of the reclining mechanisms, and being rotatable together with the cam; and
a resin bush (<NUM>) having a cylindrical shape formed with a fit hole (8e) to receive a fitting part (7c) formed on the connecting rod at a portion adjacent to each end of the connecting rod, wherein
the cam has a rod insertion hole (52a) for allowing the end (7b) of the connecting rod to be inserted therein,
the internal gear has a bush insertion hole (<NUM>) for allowing the resin bush to be inserted therein at a center position of the internal gear,
the fitting part (7c) adjacent to the end (7b) of the connecting rod fits in the fit hole (8e) of the resin bush, and the end (7b) the connecting rod (<NUM>) protrudes outward of the resin bush, and
the resin bush is placed in the bush insertion hole in contact with an inner surface of the bush insertion hole of the internal gear to retain the connecting rod (<NUM>) at such a position to the cam (<NUM>) that a clearance exists between an inner surface of the rod insertion hole (52a) of the cam (<NUM>) and an outer surface of the connecting rod (<NUM>).