JP7460893B2 - reclining device - Google Patents

Description

The present invention relates to a seat reclining device that tiltably holds a seat back relative to a seat cushion.

Conventionally, the reclining device disclosed in the following Patent Document 1 is known as a seat reclining device that holds a seat back tiltably relative to a seat cushion. This reclining device is configured such that a U-shaped connecting member that rotates with the rotating shaft and a pair of wedge-shaped members are disposed between a bush that constitutes the inner peripheral surface of an internal gear and the outer peripheral surface of a boss portion of an external gear, and the pair of wedge-shaped members are biased by a spring so as to move them apart.

With this configuration, when the rotating shaft does not rotate, the pair of wedge-shaped members fit between the connecting member and the bush due to the bias of the spring, restricting the relative rotation between the external gear and the internal gear, and maintaining the tilt angle of the seat back relative to the seat cushion. On the other hand, when the rotating shaft rotates, one of the wedge-shaped members escapes from the wedge space it was fitted in due to the frictional force received from the connecting member that rotates with the rotating shaft, and the restriction by the wedge-shaped member is released. As a result, the external gear and internal gear rotate relative to each other in response to the rotation of the rotating shaft, causing the seat back to tilt relative to the seat cushion.

JP 2011-207253 A

In the above-mentioned configuration, the U-shaped connecting member must be formed so that the radial thickness of the contact portion with the wedge-shaped member is thicker toward the tip. When the rotating shaft rotates, the wedge-shaped member receives a frictional force from the outer peripheral surface side by the U-shaped connecting member, and also receives a frictional force that tries to prevent rotation due to the frictional force from the outer peripheral surface side from the inner peripheral surface side that contacts the boss portion of the external gear. Since the pair of wedge-shaped members, the U-shaped connecting member, and the boss portion of the external gear are all made of the same metal, the frictional force from the outer peripheral surface side and the frictional force from the inner peripheral surface side are almost equal, so if the radial thickness of the U-shaped connecting member is constant, the wedge-shaped member will not rotate smoothly. For this reason, by forming the U-shaped connecting member so that the radial thickness is thicker toward the tip side, a pressure angle is generated in which the contact portion between the U-shaped connecting member and the wedge-shaped member has a smaller diameter toward the tip side, and this pressure angle can generate a force that rotates the wedge-shaped member when the rotating shaft rotates.

However, since the U-shaped connecting member is formed so that the thickness in the radial direction becomes thicker toward the tip, it is necessary to use processing methods such as precision punching or forging of thick plates, and the shape is also complicated. Therefore, there is a problem that not only is it difficult to reduce manufacturing costs, but also that workability is poor.

The present invention was made to solve the above-mentioned problems, and its purpose is to provide a configuration in which a pair of cams can be rotated in response to the rotation of a rotating shaft using a connecting member with a constant radial thickness.

In order to achieve the above object, the invention of claim 1 described in the claims is as follows:
A reclining device (20) for a seat (10) that holds a seat back (12) tiltably relative to a seat cushion (11), comprising:
a first frame (21) fixed to one of the seat cushion and the seat back, and a second frame (22) fixed to the other;
an external gear (23) connected to the first frame, having external teeth (23a) formed on an outer circumferential surface thereof, and having a resin bush (23b) formed on an inner circumferential surface thereof assembled thereto;
an internal gear (24) connected to the second frame, having internal teeth (24c) capable of meshing with the external teeth and having a greater number of teeth than the external teeth, and having a cylindrical portion (24e) facing the internal teeth on its outer circumferential surface;
A rotating shaft (25);
A connecting member (28) made of a plate material made of SK5, which has a constant radial thickness and is connected to the rotating shaft so as to slide against the outer circumferential surface of the cylindrical portion as the rotating shaft rotates;
a pair of cams (31a, 31b) made of SCM415, which are formed in a wedge shape so that the radial thickness becomes thinner toward the tip side and are interposed between the connecting member and the bush so that the tip sides are separated from each other;
A biasing member (29) that biases the pair of cams in directions away from each other;
Equipped with
The frictional force between the inner peripheral surface of the cam and the outer peripheral surface of the connecting member is greater than the frictional force between the outer peripheral surface of the cam and the inner peripheral surface of the bush .
The symbols in parentheses above indicate the corresponding relationship with the specific means described in the embodiments described later.

In the invention of claim 1, the connecting member is formed of a plate material made of SK5 and has a constant thickness in the radial direction and slides on the outer circumferential surface of the cylindrical portion of the internal gear as the rotating shaft rotates. It is formed into a wedge shape so that the thickness in the radial direction becomes thinner toward the distal end, and is interposed between the connecting member and the resin bushing that constitutes the inner circumferential surface of the external gear so that the distal ends are separated from each other. A pair of SCM415 cams to be inserted and a biasing member that biases the pair of cams in a direction to move them away from each other are provided.

As a result, when the rotating shaft does not rotate, the pair of cams fit into the wedge spaces formed by the connecting member and the bushing due to the biasing force of the urging member, so that the rotating shaft does not rotate when the rotating shaft is not rotating. Relative rotation between the toothed gear and the internal gear is regulated. On the other hand, when the rotating shaft rotates in one direction, one cam receives a frictional force along the urging direction of the urging member due to the connecting member rotating together with the rotating shaft, and the other cam receives a frictional force along the urging direction of the urging member. Frictional force is applied from the inner circumferential surface side against the biasing direction. At this time, the other cam receives a frictional force from the outer circumferential surface that is in contact with the bush, which attempts to prevent rotation due to the frictional force from the inner circumferential surface. Since the connecting member and the pair of cams are made of metal, and the bushing is made of resin, the frictional force from the inner circumferential side (the force that tries to rotate) is the frictional force from the outer circumferential side (the force that prevents rotation). ), the other cam can be rotated against the biasing force of the biasing member. Further, when the rotating shaft rotates in the opposite direction, one of the cams can be rotated against the biasing force of the biasing member by the connecting member that rotates together with the rotating shaft. Therefore, it is possible to realize a configuration in which the pair of cams can be rotated in accordance with the rotation of the rotating shaft using a connecting member having a constant thickness in the radial direction.

In the invention of claim 2, a recess that is recessed in the axial direction is formed in the connecting member, and a protrusion that fits into the recess so as to leave a predetermined circumferential gap is formed in the cam. As a result, when the cam rotates together with the connecting member due to frictional force from the inner peripheral surface side via the connecting member, the recess and the protrusion that fits into the recess rotate together while maintaining the gap. Even if the rotation between the cam and the connecting member temporarily deviates, the edge of the recess comes into contact with the protrusion, so that the contact state between the recess and the protrusion is maintained, allowing the cam and the connecting member to rotate together.

1 is a side view conceptually showing an example of a vehicle seat equipped with a reclining device of the present invention. It is a side view of a reclining device. 3 is an exploded perspective view of the reclining device of FIG. 2. FIG. FIG. 5(A) is a front view of the connecting member of FIG. 4, and FIG. 5(B) is a side view of the connecting member of FIG. 4. FIG. 3 is a perspective view of a pair of cams. 7A is a front view of one of the cams in FIG. 6, and FIG. 7B is a side view of one of the cams in FIG. 3 is a cross-sectional view taken along the line X1-X1 shown in FIG. 2. FIG. 3 is a cross-sectional view taken along line X2-X2 of FIG. 2. FIG. 6 is an explanatory diagram illustrating the relationship between the frictional force from the inner circumferential surface side and the frictional force from the outer circumferential surface side that the cam receives when the connecting member rotates. 10 is a cross-sectional view illustrating a state in which the shaft, the connecting member, the pair of cams, and the external gear are rotated from the state shown in FIG. 9 .

[First embodiment]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a vehicle seat 10 equipped with a reclining device 20 according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, a vehicle seat 10 equipped with a reclining device 20 of the present invention includes a seat cushion 11 that supports the seat portion of a seated occupant, and a seat back 12 that is tiltable relative to the seat cushion 11 and supports the back portion of the seated occupant.

A seat cushion frame 11a serving as a skeleton of the seat cushion 11 and a seat back frame 12a serving as a skeleton of the seat back 12 are a first frame 21 and a second frame of a reclining device 20 installed at the ends of the seat cushion frame 11a. They are connected via 22 and the like. The seat back 12 can be tilted relative to the seat cushion 11 in accordance with the rotational drive of a tilting motor (not shown) provided in the reclining device 20.

Next, the configuration of the reclining device 20 will be described with reference to the drawings.
2 and 3, the reclining device 20 includes, in addition to the above-mentioned frames 21 and 22, an external gear 23, an internal gear 24, a shaft 25, a plate cover 26, a shaft cover 27, a connecting member 28, a spring 29, and a pair of cams 31a and 31b. For ease of explanation, the frames 21 and 22 are omitted in FIG. 2.

As shown in FIG. 3, the external gear 23 is formed in a substantially annular shape, and external teeth 23a are formed on the outer peripheral surface thereof. In addition, a cylindrical resin bush 23b with a small coefficient of friction is fitted into the inner circumferential surface of the external gear 23 in order to have excellent wear resistance and reduce the frictional force at the contact area between the cams 31a and 31b. It is. That is, the external gear 23 is assembled with a resin bush 23b forming an inner circumferential surface. Further, on the side surface of the external gear 23 on the first frame 21 side, four substantially arc-shaped protrusions 23c for assembly to the first frame 21 are provided.

As shown in FIG. 3, the internal gear 24 includes an outer cylindrical part 24a in which internal teeth 24c are formed on the inner circumferential surface, and a side plate part in which a cylindrical inner cylindrical part 24e is formed around a through hole 24d. 24b. The internal teeth 24c are formed to have a larger number of teeth than the external teeth 23a so as to mesh eccentrically with the external teeth 23a. Specifically, for example, when the number of teeth of the external teeth 23a is set to 32, the number of teeth of the internal teeth 24c is set to 33.

Further, the width (axial length) of the internal teeth 24c is set to be longer than the width of the external teeth 23a, and the portion on the side plate portion 24b side is located between the external gear 23 and the internal gear 24. It is formed so as not to mesh with the external teeth 23a during meshing. Further, the side plate portion 24b is provided with three substantially arc-shaped projections 24f for fixing the internal gear 24 to the second frame 22. Note that the inner cylinder portion 24e may correspond to an example of a “cylindrical portion”.

As shown in FIG. 3, the shaft 25 is a rotating shaft made of resin, and is formed to be coaxial and rotatably fitted to the inner cylinder portion 24e of the internal gear 24. As shown in FIG. This shaft 25 is rotated at a predetermined reduction ratio according to the rotational drive of the tilting motor when tilting the seat back 12 with respect to the seat cushion 11. Serrations are formed to connect rotating members that rotate in accordance with the rotational drive of the motor. Furthermore, a plurality of engagement protrusions 25a for engaging with the connecting member 28 are provided at the end of the shaft 25 on the first frame 21 side.

The connecting member 28 and the pair of cams 31a, 31b are arranged (inserted) between the bush 23b that constitutes the inner peripheral surface of the external gear 23 and the outer peripheral surface of the inner cylindrical portion 24e of the internal gear 24. With the internal gear 24 being eccentric with respect to the external gear 23, a part of the internal teeth 24c is meshed with the external teeth 23a.

As shown in FIGS. 4 and 5, the connecting member 28 is formed by pressing a bent plate material made of metal (for example, SK5), and has a constant thickness in the radial direction except for the gap 28a. It is formed into a thin cylindrical shape. The connecting member 28 is formed with a plurality of engagement recesses 28b on the first frame 21 side, into which the respective engagement protrusions 25a of the shaft 25 engage, and on the second frame 22 side, two recesses 28c are formed. . The connecting member 28 is formed so that its inner circumferential surface is slidable on the outer circumferential surface of the inner cylindrical portion 24e.

Since the pair of cams 31a, 31b shown in FIG. 3 and FIG. 6 have symmetrical shapes, the detailed shape of the cam 31a will be described below.
As shown in Fig. 6 and Fig. 7, the cam 31a is a wedge-shaped member made of metal (e.g., SCM415), and is formed in a wedge shape so that the radial thickness becomes thinner toward the tip side, except for the protruding portion 32 provided at the tip. For example, as shown in Fig. 7(A), the radial thickness t1 of the tip side portion of the cam 31a is thinner than the radial thickness t2 of the base end side (opposite tip side) portion of the cam 31a. The protruding portion 32 is inserted into the recessed portion 28c of the connecting member 28 through a gap in the interposed state described later, and is formed so that its circumferential length is shorter than that of the recessed portion 28c. A groove portion 33 is provided on the end surface on the base end side of the cam 31a to receive the urging force from the spring 29 functioning as a urging member.

The connecting member 28 and the pair of cams 31a, 31b configured as described above are connected to the bush 23b of the external gear 23 in the meshing state, as shown in FIGS. and the outer peripheral surface of the inner cylindrical portion 24e of the internal gear 24. The pair of cams 31a and 31b are urged by the spring 29 in directions away from each other. Further, as shown in FIG. 8, the connecting member 28 is engaged with the engaging protrusion 25a of the shaft 25 at the engaging recess 28b, and is in a state where it can rotate together with the shaft 25.

In this interposed state, the plate cover 26 is welded to the end of the outer cylinder portion 24a of the meshed internal gear 24, restricting the axial movement of the external gear 23. Then, with the shaft 25 and other parts positioned with the shaft cover 27, the external gear 23 is welded to the first frame 21 using the protrusion 23c, and the internal gear 24 is welded to the second frame 22 using the protrusion 24f, completing the assembly of the reclining device 20.

Next, the characteristic configuration of this embodiment will be explained with reference to FIGS. 9 to 11.
In the inserted state as described above, as shown in FIG. By receiving the force, the outer peripheral side comes into surface contact with the bush 23b, and the inner peripheral side comes into surface contact with the connecting member 28.

In this contact state, when the shaft 25 does not rotate, the pair of cams 31a, 31b are biased by the spring 29 to fit into the wedge space formed by the connecting member 28 and the bush 23b, thereby restricting the relative rotation between the external gear 23 and the internal gear 24 when the shaft 25 does not rotate.

In contrast, as shown in Figure 10, when shaft 25 rotates in the direction of arrow S, cam 31b receives a frictional force in the urging direction of spring 29 due to connecting member 28 rotating with shaft 25, and cam 31a receives frictional force F1 from the inner peripheral surface side against the urging direction of spring 29. At that time, cam 31a receives frictional force F2 from the outer peripheral surface side in contact with bush 23b, which tries to prevent rotation due to frictional force F1 from the inner peripheral surface side.

The connecting member 28 and the pair of cams 31a, 31b are made of metal, and the bushing 23b is made of resin with a low friction coefficient, so that the frictional force F1 from the inner peripheral surface (the force that causes rotation) is greater than the frictional force F2 from the outer peripheral surface (the force that prevents rotation). Therefore, even if the connecting member 28 has a constant radial thickness, the cam 31a can be rotated against the bias of the spring 29 so as to escape from the wedge space in which it was fitted. As a result, as shown in FIG. 11, the external gear 23, which receives a frictional force in the rotational direction from the cam 31b that rotates together with the connecting member 28, can be rotated in the direction of the arrow S together with the cam 31a and cam 31b.

Further, when the shaft 25 rotates in the opposite direction to the arrow S, the coupling member 28 rotating together with the shaft 25 causes the cam 31b to be biased by the spring 29 so as to come out of the wedge space in which it has been fitted. can be rotated in the opposite direction.

As described above, the reclining device 20 according to this embodiment is provided with a metal connecting member 28 that has a constant radial thickness and slides against the outer peripheral surface of the inner cylinder portion 24e of the internal gear 24 as the shaft 25 rotates, a pair of metal cams 31a, 31b that are wedge-shaped so that their radial thickness decreases toward the tip and are inserted between the connecting member 28 and the resin bushing 23b that constitutes the inner peripheral surface of the external gear 23 so that their tip sides move away from each other, and a spring 29 that biases the pair of cams 31a, 31b in a direction that moves them away from each other.

With this configuration, even if the connecting member 28 has a constant thickness in the radial direction, the cam 31a or the cam 31b can resist the urging by the spring 29 so as to come out of the wedge space in which it has been fitted. can be rotated. Therefore, the connecting member 28 can be formed using a processing method that is easy to work with and is inexpensive, such as press processing.

In particular, because the connecting member 28 is formed with a constant radial thickness, the frictional force generated between the connecting member 28 and the wedge-shaped cams (31a, 31b) is less likely to vary compared to when the connecting member 28 is formed with a radial thickness that increases toward the tip, which allows the external gear 23 to rotate smoothly and further stabilizes the behavior of the seat cushion 11 when tilting.

Further, the connecting member 28 is formed with two recesses 28c recessed in the axial direction on the second frame 22 side, and the pair of cams 31a and 31b are inserted into the recesses 28c with a predetermined gap therebetween. Convex portions 32 are respectively formed.

As a result, when the cam 31a (31b) rotates together with the connecting member 28 due to the frictional force F1 from the inner peripheral surface side via the connecting member 28, the recess 28c and the protrusion 32 that has entered the recess 28c rotate together so as to maintain a gap (see FIG. 11). Even if the rotation between the cam 31a (31b) and the connecting member 28 temporarily deviates, the edge of the recess 28c comes into contact with the protrusion 32, so that the contact state between the recess 28c and the protrusion 32 is maintained, and the cam 31a (31b) and the connecting member 28 can rotate together.

[Other embodiments]
Note that the present invention is not limited to the above-described embodiments and modifications, and may be embodied as follows, for example.
(1) The connecting member 28 and the shaft 25 are not limited to being connected so as to rotate coaxially by the engagement between the engaging recess 28b and the engaging protrusion 25a. The convex portion formed in the shaft 25 may be connected to rotate coaxially by fitting the convex portion formed in the shaft 25 with the concave portion formed in the shaft 25.

(2) The first frame 21 is not limited to being connected to the seat cushion frame 11a and the second frame 22 is connected to the seat back frame 12a, but the first frame 21 may be connected to the seat back frame 12a and the second frame 22 may be connected to the seat cushion frame 11a. In addition, the first frame 21 and the second frame 22 may be part of the seat cushion frame 11a or the seat back frame 12a.

REFERENCE SIGNS LIST 10: vehicle seat 11: seat cushion 12: seat back 20: reclining device 21: first frame 22: second frame 23: external gear 23a: external teeth 23b: bush 24: internal gear 24c: internal teeth 24e: inner tube portion (cylindrical portion)
25...Shaft (rotating shaft)
28: connecting member 28c: recess 29: spring (urging member)
31a, 31b... Cam 32... Convex portion

Claims (2)

A seat reclining device that tiltably holds a seat back relative to a seat cushion,
a first frame fixed to one of the seat cushion and the seat back, and a second frame fixed to the other;
an external gear that is connected to the first frame, has external teeth formed on its outer peripheral surface, and is assembled with a resin bush that forms its inner peripheral surface;
Internal teeth are formed that are connected to the second frame and can mesh with the external teeth and have a larger number of teeth than the external teeth, and have a cylindrical portion that faces the internal teeth on the outer circumferential surface. gears and
a rotating shaft;
A connecting member formed from a plate material made of SK5, which has a constant thickness in the radial direction and slides on the outer circumferential surface of the cylindrical portion as the rotating shaft rotates by being connected to the rotating shaft. and,
a pair of SCM415 cams formed in a wedge shape so that the thickness in the radial direction becomes thinner toward the distal end, and inserted between the connecting member and the bush so that the distal ends are separated from each other;
a biasing member that biases the pair of cams in a direction to separate them from each other;
Equipped with
A reclining device characterized in that the frictional force between the inner circumferential surface of the cam and the outer circumferential surface of the connecting member is greater than the frictional force between the outer circumferential surface of the cam and the inner circumferential surface of the bushing . The connecting member is formed with a recess that is recessed in the axial direction,
2. The reclining device according to claim 1, wherein the cam is formed with a protrusion that fits into the recess with a predetermined circumferential gap therebetween.

Images