Reclining device

Abstract

To provide a reclining device that enables an internal tooth gear and an external tooth gear to move in an eccentric direction so that sides of the external tooth gear and of the internal tooth gear surely engage with each other at the time of locking, so that members contact cylindrical bosses of the gears, in many areas, at the time of sliding, which can stabilize the sliding.SOLUTION: A reclining device 100 according to the present invention comprises: an external tooth gear 10; an internal tooth gear 20; a U-shaped partial-ring 40 in which a center of an outer peripheral surface formed in a circular shape and a center of an inner peripheral surface formed in a circular shape are mutually eccentrically formed and a through-hole for an elastic body is formed; a rotary shaft 30 having an extended pressing part that presses the U-shaped partial-ring 40; a pair of wedge-shaped cams 50 arranged at a back surface side of the U-shaped partial-ring 40; and an elastic body 60 that energizes the pair of wedge-shaped cams 50 in a direction in which the cams separate from each other, through the through-hole for the elastic body of the U-shaped partial-ring 40.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a reclining device. [Background technology]

[0002] BACKGROUND ART Various seat reclining devices that hold a seat back tiltably relative to a seat cushion have been proposed (for example, Patent Document 1, etc.). As shown in FIG. 8, one such recliner 300 includes an external gear 310 having a through hole 312 on its inner circumferential surface that is coaxial with the axial direction; an internal gear 320 having internal teeth on its outer circumferential surface that can mesh with the external teeth and a cylindrical boss 322 on its inner circumferential surface that is coaxial with the axial direction; a rotating shaft 330 that is coaxially and rotatably fitted to the external gear 310 and rotates either the external gear 310 or the internal gear 320 around the gear axis of the other; a bushing 340 that is provided between the through hole 312 and the cylindrical boss 322; and a pair of wedge-shaped cams 350 that are provided on the bushing 340 and that simultaneously contact the cylindrical boss 322 and the bushing 340 to restrict rotation between the cylindrical boss 322 and the bushing 340 and slide at least one of the cylindrical boss 322 and the bushing 340, thereby allowing rotation between the cylindrical boss 322 and the bushing 340.

[0003] In the reclining device 300 configured as described above, when the external gear 310 and the internal gear 320 are eccentrically meshed, the contact point (μ) between the bushing 340 on the side opposite to the meshed side and the through hole 312 of the external gear 310 requires a gap because the external gear 310 must move slightly up and down relative to the internal gear 320 in order for the external gear 310 to rotate relative to the internal gear 320. Even in the locked state, a gap is required to efficiently and reliably mesh the external gear 310 and the internal gear 320 and prevent rattle. However, during sliding, contact around the entire circumference of the bushing allows for efficient transmission of force and serves as a bearing, stabilizing sliding and ensuring smooth rotation, so it is preferable not to leave a gap at this contact point (μ).

[0004] In this way, there was a problem in that a technical contradiction occurred in that a gap was necessary from the viewpoint of the need for rotation and preventing rattle, but no gap was desired for stability during sliding. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-127210 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the present invention has been made in consideration of these problems, and aims to provide a reclining device that allows the internal gear and the external gear to move eccentrically to the extent that the meshing sides of the external gear and the internal gear are securely meshed when locked, and that can stabilize sliding even when sliding by having a large area of contact between the member and the cylindrical boss of the gear. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs the following means.

[0008] The reclining device of the present invention is a seat reclining device that tiltably holds a seat back frame that constitutes a seat back relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having external teeth formed on an outer peripheral surface and a through hole formed coaxially with the axial direction on an inner peripheral surface; an internal gear attached directly or indirectly to the other of the seat cushion frame and the seat back frame, the internal gear having internal teeth on an inner circumferential surface that are capable of meshing with the external teeth, the internal teeth being at least one more than the external teeth, and the internal gear having a cylindrical boss formed thereon that is coaxial with the axial direction; a U-shaped ring disposed between the inner periphery of the through hole of the external gear and the outer periphery of the cylindrical boss of the internal gear, the center of the circularly formed outer periphery and the center of the circularly formed inner periphery being eccentric, and the U-shaped ring having an elastic body through hole formed therein; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear, that extends into the open portion of the U-shaped ring, and that has a pressing extension that presses the U-shaped ring; a pair of wedge-shaped cams that are arranged on the back side of the U-shaped ring and that restrict relative rotation between the external gear and the internal gear by contacting the outer circumferential surface of the cylindrical boss of the internal gear with the inner circumferential surface of the through hole of the external gear, and that allow relative rotation between the external gear and the internal gear by rotating the rotating shaft so that the outer circumferential surface of the cylindrical boss of the internal gear slides on the inner circumferential surface of the through hole of the external gear; and an elastic body that biases the pair of wedge-shaped cams in directions separating them from each other via the elastic body through-holes of the U-shaped ring.

[0009] In this invention, by arranging a wedge-shaped cam on the back side of the U-shaped ring and stacking them in two stages, the U-shaped ring, which ensures contact with the cylindrical boss, and the wedge-shaped cam, which moves the external gear in the direction to mesh with the internal gear, are separated, allowing the external gear to move toward the internal gear and mesh effectively while keeping the U-shaped ring in contact with most of the bearing of the cylindrical boss. This prevents rattle in the locked state and stabilizes sliding during sliding, ensuring smooth rotation.

[0010] Furthermore, the reclining device according to the present invention may be characterized in that it is provided with an approximately U-shaped bushing on the outer periphery of the wedge-shaped cam, and the wedge-shaped cam restricts the relative rotation between the external gear and the internal gear by contacting the outer periphery of the cylindrical boss of the internal gear with the inner periphery of the bushing, and allows the relative rotation between the external gear and the internal gear by sliding the bushing against the cylindrical boss of the internal gear or the bushing against the inner periphery of the through hole of the external gear.

[0011] By adopting such a configuration, the U-shaped ring ensures contact with the cylindrical boss, and the wedge-shaped cam ensures meshing between the internal gear and the external gear, ensuring a two-tiered configuration, while reducing the time lag for movement of the wedge-shaped cam and enabling quick operation.

[0012] Further, in the reclining device according to the present invention, a seat reclining device is provided which tiltably holds a seat back frame constituting a seat back relative to a seat cushion frame constituting a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having external teeth formed on an outer peripheral surface and a cylindrical boss formed coaxially with the axial direction on an inner peripheral surface; an internal gear attached directly or indirectly to the other of the seat cushion frame and the seat back frame, the internal gear having internal teeth on an inner circumferential surface that are capable of meshing with the external teeth, the internal teeth being at least one more than the external teeth, and having a through hole formed therein that is coaxial with the axial direction; a U-shaped ring disposed between the inner periphery of the through hole of the internal gear and the outer periphery of the cylindrical boss of the external gear, the center of the circularly formed outer periphery and the center of the circularly formed inner periphery being eccentric, and the U-shaped ring having an elastic body through hole formed therein; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear, that extends into the open portion of the U-shaped ring, and that has a pressing extension that presses the U-shaped ring; a pair of wedge-shaped cams that are arranged on the back side of the U-shaped ring and that restrict relative rotation between the external gear and the internal gear by contacting the outer circumferential surface of the cylindrical boss of the external gear with the inner circumferential surface of the through hole of the internal gear, and that allow relative rotation between the external gear and the internal gear by rotating the rotating shaft so that the outer circumferential surface of the cylindrical boss of the external gear slides against the outer circumferential surface of the through hole of the internal gear; and an elastic body that biases the pair of wedge-shaped cams in directions separating them from each other via the elastic body through-holes of the U-shaped ring.

[0013] This invention differs from the above-mentioned invention in that a cylindrical boss is provided on the external gear and a through hole is formed in the internal gear, but similarly, by using a two-tiered configuration with a wedge-shaped cam positioned on the back side of the U-shaped ring, the functions of the U-shaped ring, which ensures contact with the cylindrical boss, and the wedge-shaped cam, which moves the external gear in the direction of meshing with the internal gear, are separated, thereby preventing rattling in the locked state and stabilizing sliding during sliding, ensuring smooth rotation.

[0014] In addition, in the reclining device according to the present invention, A substantially U-shaped bush is provided on the outer periphery of the wedge-shaped cam, The wedge-shaped cam may be characterized in that it regulates the relative rotation between the external gear and the internal gear by contacting the outer peripheral surface of the cylindrical boss of the external gear with the inner peripheral surface of the bush, and allows the relative rotation between the external gear and the internal gear by sliding the bush against the cylindrical boss of the external gear or the bush against the inner peripheral surface of the through hole of the internal gear.

[0015] With this configuration, the U-shaped ring ensures contact with the cylindrical boss, and the wedge-shaped cam ensures meshing between the internal gear and external gear, ensuring a two-tiered configuration, while reducing the time lag for movement of the wedge-shaped cam and enabling quick operation. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a vehicle seat 200 to which a reclining device 100 according to the first embodiment is attached. [Figure 2] FIG. 2 is a front view showing the internal structure of the reclining device 100 according to the first embodiment. [Figure 3] FIG. 3 is an exploded perspective view of the reclining device 100 according to the first embodiment. [Figure 4] FIG. 4 is a front view of the U-shaped ring 40 according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the reclining device 100 taken along line AA according to the first embodiment. [Figure 6] FIG. 6 is an exploded perspective view of the reclining device 100 according to the second embodiment. [Figure 7] FIG. 7 is an exploded perspective view of the reclining device 100 according to the third embodiment. [Figure 8] FIG. 8 is a front view of a conventional reclining device 300. DETAILED DESCRIPTION OF THE INVENTION

[0017] A reclining device 100 according to an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram of a vehicle seat 200, FIG. 2 is a front view showing the internal structure of the reclining device 100, FIG. 3 is an exploded perspective view of the reclining device 100, and FIG. 5 is a cross-sectional view taken along line AA in FIG. 2. Note that the embodiments and drawings described below exemplify some of the embodiments of the present invention and are not intended to limit the present invention to these configurations. Note that corresponding components in each drawing are denoted by the same or similar reference numerals. Also, in FIG. 3, as indicated by the arrows in the drawing, the direction toward the external gear 10 is referred to as the "front" and the direction toward the internal gear 20 is referred to as the "rear."

[0018] (First embodiment) 1, the reclining device 100 according to the first embodiment is a device attached to a seat cushion 210 of a vehicle seat 200 at a tilting center position of a seat back 220 that is tiltably attached to the seat cushion 210, and provides a tilting function to the seat back 220. Specifically, the reclining device 100 is attached between a seat cushion frame disposed inside the seat cushion 210 and a seat back frame disposed inside the seat back 220, either directly or indirectly via another attachment plate 230 (hereinafter referred to as "attachment plate or the like").

[0019] 2 and 3, the reclining device 100 according to the present invention mainly comprises an external gear 10, an internal gear 20, a rotating shaft 30, a U-shaped ring 40, a wedge-shaped cam 50, a spring 60 as an elastic body, a spring cover 70, and a plate cover 80. Note that in FIG. 2, the spring 60, spring cover 70, and plate cover 80 are omitted to make the internal structure easier to see.

[0020] 3, the external gear 10 is formed in a disk shape, with external teeth 11 formed on its outer circumferential surface and a cylindrical through-hole 12 formed in its center. The external gear 10 has a protrusion 13 on its front surface 10b, which is fitted into a fitting hole formed in a mounting plate or the like 230 and is attached to the vehicle seat by welding or the like.

[0021] The internal gear 20 is formed in a disk shape with a larger diameter than the external gear 10. A cylindrical recess is formed so that the external gear 10 can be mounted inside, and internal teeth 21 are formed on the inner circumferential surface of this recess. The number of internal teeth 21 is at least one more than the number of external teeth 11 of the external gear 10. As shown in FIG. 2, the external gear 10 and the internal gear 20 mesh with the internal teeth 21 and the external teeth 11 so that the center C1 of the external gear 10 and the center C2 of the internal gear 20 are eccentric, respectively. Therefore, the external gear 10 and the internal gear 20 form a differential gear, and when the internal gear 20 makes one revolution around the external teeth 11, it rotates by the difference in the number of teeth between the internal teeth 21 and the external teeth 11. In other words, for example, if there is only one tooth difference, when the external gear 10 makes one revolution around the internal gear 20, it rotates by one tooth. A cylindrical boss 22 is provided at the center of the internal gear 20, as shown in FIG. 3. A protrusion 23 is provided on the back surface of the internal gear 20, and is attached to the vehicle seat by welding or the like in a state where it fits into a fitting hole provided in a mounting plate or the like 230.

[0022] The rotating shaft 30 is coaxially rotatably inserted into the cylindrical boss 22 of the internal gear 20. The rotating shaft 30 is rotated when adjusting the tilt of the seat back 220, and serrations 31 are provided on the inner cylindrical surface to receive the rotational force of the tilting motor. The rotating shaft 30 also has a pressing extension 32 extending between the spaced-side ends 54 of a pair of wedge-shaped cams 50a, 50b (described later). The pressing extension 32 is disposed with a width substantially equal to or slightly larger than the distance between the spaced-side ends 54 of the pair of wedge-shaped cams 50a, 50b and the rotating shaft 30, so that the wedge-shaped cams 50 can be pressed by rotating the rotating shaft 30. The inner surface 32a of the pressing extension 32 on the cylindrical boss 22 side is preferably fabricated to contact the cylindrical boss 22. By forming it to contact the cylindrical boss 22, the pressed and extended portion 32 of the rotating shaft 30 and the U-shaped ring 40 can be in contact with each other over almost the entire circumference of the outer surface 22a of the cylindrical boss 22, thereby stabilizing sliding and ensuring smooth rotation.

[0023] The U-shaped ring 40 is disposed between the inner peripheral surface of the through hole 12 of the external gear 10 and the outer peripheral surface 22a of the cylindrical boss 22 of the internal gear 20. As shown in FIG. 4 , the U-shaped ring 40 is formed by partially opening an annular member eccentrically formed so that the center of the circular outer peripheral surface 41 and the center of the circular inner peripheral surface 42 are equal to the eccentricity between the centers of the external gear 10 and the internal gear 20. An elongated through hole 43 for an elastic body is formed to include the widest portion d. The portion that would be the narrowest in a circular ring shape is also open. The U-shaped ring 40 is formed to contact the cylindrical boss 22 of the internal gear 20 as little as possible, but is fabricated with a gap relative to the through hole 12 of the external gear 10 that allows the external gear 10 to move in the eccentric direction between the centers of the external gear 10 and the internal gear 20.

[0024] The wedge-shaped cams 50a and 50b are formed symmetrically with respect to a plane, as shown in Fig. 3, with the concave surface 51 (inner surface) of the wedge-shaped cam 50 having the same curve as the curved surface of the outer peripheral surface 22a of the cylindrical boss 22, and the convex surface 52 (outer surface) being formed so that the thickness gradually decreases from the opposing side. The wedge-shaped cams 50a and 50b are arranged so that their thicker near-side ends 53 face each other, and are disposed on the back side of the U-shaped ring 40 so as to be in contact with the inner peripheral surface 12a of the through hole 12 of the external gear 10 and the outer peripheral surface 22a of the cylindrical boss 22 of the internal gear 20, as shown in Fig. 5, with the far-side end 54 opposite the near-side end 53 being located near the open portion of the U-shaped ring 40. Preferably, the remote end 54 is arranged to slightly protrude from the open portion of the U-shaped ring 40. By forming it to protrude slightly, the pressing extension 32 can directly press the wedge-shaped cam 50 when the rotating shaft 30 is rotated.

[0025] 3, the spring 60 is made of an elastic body and has an annular portion 61 and end portions 62a, 62b that rise up so as to be bent at 90 degrees from the annular portion 61. The end portions 62a, 62b are in contact with the proximal end portion 53 of the wedge-shaped cam 50 via the elastic body through-holes 43 of the U-shaped ring 40, and urge the pair of wedge-shaped cams 50a and 50b in directions that move them apart.

[0026] The reclining device 100 thus manufactured operates as follows: When no force is applied to the rotating shaft 30 and the rotating shaft 30 is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in directions separating them, and are in contact with the inner circumferential surface 12a of the through hole 12 of the external gear 10 and the outer circumferential surface 22a of the cylindrical boss 22 of the internal gear 20. As a result, the relative movement between the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0027] From this locked state, when the rotating shaft 30 is rotated counterclockwise, for example, in FIG. 2, the wedge-shaped cam 50b is pressed by the pressed extension 32 of the rotating shaft 30. A wedge angle is set between the wedge-shaped cam 50b and the inner peripheral surface 12a of the through hole 12 of the external gear 10. The pressure of the wedge-shaped cam 50b creates a gap between the wedge-angle inner peripheral surface and the wedge-shaped cam 50b, causing the wedge to disengage. This creates gaps between the wedge-shaped cam 50 and the cylindrical boss 22 and between the wedge-shaped cam 50 and the through hole 12 of the external gear 10, allowing the external gear 10 to rotate relative to the internal gear 20. Furthermore, the U-shaped ring 40 rotates counterclockwise relative to the internal gear 20, and the biasing force of the spring 60 causes the wedge-shaped cam 50a to rotate counterclockwise to fill the gap. The wedge-shaped cam 50 rotates counterclockwise while sliding together with the rotating shaft 30 and the U-shaped ring 40. In this way, the external gear 10, the internal gear 20, and the rotating shaft 30 constitute a differential gear mechanism. Clockwise rotation can also be achieved in the same way.

[0028] The reclining device 100 thus manufactured is in a state in which the U-shaped ring 40 is in contact with most of the outer surface 22a of the cylindrical boss 22 (generally 80% or more of the outer surface 22a), which stabilizes the sliding and ensures smooth rotation during sliding, and since the wedge-shaped cam 50 urges the external gear 10 to move in an eccentric direction relative to the internal gear 20, it is possible to prevent rattling when in the locked state.

[0029] (Second embodiment) An exploded perspective view of the reclining device 100 according to the second embodiment is shown in Figure 6. The reclining device 100 according to the second embodiment has the same configuration as the first embodiment except for the addition of a bushing 90 and the shape and arrangement of the wedge-shaped cam 50, so a description thereof will be omitted.

[0030] The reclining device 100 according to the second embodiment differs in that it includes a substantially U-shaped bushing 90 on the convex surface 52 (outer surface) side of the wedge-shaped cam 50. As shown in FIG. 6, the substantially U-shaped bushing 90 is formed in a substantially U-shape, and both bushing ends 91a and 91b forming the annular opening are disposed so as to extend from the annular opening of the U-shaped ring 40. In other words, the annular opening of the bushing 90 is formed with a narrower spacing than the annular opening of the U-shaped ring 40. The wedge-shaped cam 50 is formed smaller than that of the first embodiment so as to fit within the inner circumference of the bushing 90. Note that the wedge-shaped cam 50 moves in conjunction with the movement of the bushing 90, and therefore the remote-side end 54 does not need to extend to the annular opening of the U-shaped ring 40 as in the first embodiment. The wedge-shaped cam 50 restricts the relative rotation between the external gear 10 and the internal gear 20 by contacting the outer surface 22a of the cylindrical boss 22 of the internal gear 20 with the inner surface of the bush 90, and allows the relative rotation between the external gear 10 and the internal gear 20 by sliding the bush 90 against the cylindrical boss 22 of the internal gear 20 or the bush 90 against the inner surface of the through hole 12 of the external gear 10.

[0031] In the reclining device 100 manufactured as described above, when no force is applied to the rotating shaft 30 and the rotating shaft 30 is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in directions separating them, and the inner peripheral surface of the bushing is in contact with the outer peripheral surface 22a of the cylindrical boss 22 of the internal gear 20. Therefore, the relative movement between the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0032] When the rotating shaft 30 is rotated counterclockwise from this locked state, the pressed and extended portion 32 of the rotating shaft 30 presses the bushing 90, causing it to rotate in the same manner. A wedge angle is set between the inner wall surface of the bushing 90, and the inner wall of the wedge angle is in contact with the wedge-shaped cam 50. As the bushing 90 rotates, a gap is created between the inner wall of the wedge angle and the wedge-shaped cam 50, causing the wedge to disengage. The rotating shaft 30 and the bushing 90 rotate counterclockwise relative to the internal gear 20. As a result, gaps are created between the bushing 90 and the cylindrical boss 22 and between the bushing 90 and the through hole 12 of the external gear 10, allowing the external gear 10 to rotate relative to the internal gear 20. Accordingly, the wedge-shaped cam 50a rotates counterclockwise due to the biasing force of the spring 60, filling the gap. The wedge-shaped cam 50 rotates counterclockwise, sliding along with the rotating shaft 30 and the bushing 90. Clockwise rotation can also be achieved in the same manner.

[0033] The U-shaped ring 40 ensures contact with the cylindrical boss 22, and the wedge-shaped cam 50 ensures meshing between the internal gear 20 and the external gear 10 in a two-tiered configuration. This provides the same effects as the first embodiment, while reducing the time lag for the movement of the wedge-shaped cam 50 and enabling quick operation in response to the rotational movement of the rotating shaft 30.

[0034] (Third embodiment) A reclining device 100 according to a third embodiment is shown in FIG. 7. The reclining device 100 according to the third embodiment differs from the reclining device 100 according to the first embodiment in that a cylindrical boss 14 is provided at the center of the external gear 10 and a through-hole 25 is provided at the center of the internal gear 20. Also, a spring cover 70 that prevents axial movement of the rotating shaft 30, U-shaped ring 40, wedge-shaped cam 50, and spring 60 is provided on the back side of the internal gear 20, and this spring cover 70 has a protrusion 71 that fits into a fitting hole in a mounting plate or the like 230. Meanwhile, a plate cover 80 is made of an annular metal plate, is positioned on the front side of the external gear 10, and is fixed to the outer peripheral end of the internal gear 20 by welding or the like to restrict axial movement of the external gear 10.

[0035] The rotating shaft 30, U-shaped ring 40, wedge-shaped cam 50, and spring 60 are arranged symmetrically with respect to the first embodiment. The U-shaped ring 40 is arranged between the outer peripheral surface 14a of the cylindrical boss 14 of the external gear 10 and the through hole 25 of the internal gear 20, with the cylindrical boss 14 inserted into the inner peripheral surface of the U-shaped ring 40. The rotating shaft 30 is arranged inside the cylindrical boss 14 so as to rotate coaxially with the central axis of the cylindrical boss 14, and as in the first embodiment, a pressing extension 32 is provided that presses the wedge-shaped cam 50, allowing the wedge-shaped cam 50 to rotate either clockwise or counterclockwise.

[0036] The reclining device 100 thus manufactured operates as follows: When no force is applied to the rotating shaft 30 and the rotating shaft 30 is not rotating, the pair of wedge-shaped cams 50a and 50b are biased by the spring 60 in directions separating them, and are in contact with the inner circumferential surface 25a of the through hole 25 of the internal gear 20 and the outer circumferential surface 14a of the cylindrical boss 14 of the external gear 10. As a result, the relative movement between the internal gear 20 and the external gear 10 is locked, and the seat back 220 is in a locked state.

[0037] When the rotating shaft 30 is rotated counterclockwise from this locked state, the wedge-shaped cam 50b is pressed by the pressed extension 32 of the rotating shaft 30. A wedge angle is set between the wedge-shaped cam 50b and the inner peripheral surface 25a of the through hole 25 of the internal gear 20. The pressure of the wedge-shaped cam 50b creates a gap between the wedge-angle inner peripheral surface and the wedge-shaped cam 50b, causing the wedge to disengage. This creates gaps between the wedge-shaped cam 50 and the cylindrical boss 14 and between the wedge-shaped cam 50 and the through hole 25 of the internal gear 20, allowing the external gear 10 to rotate relative to the internal gear 20. Furthermore, the U-shaped ring 40 rotates counterclockwise relative to the internal gear 20, and the biasing force of the spring 60 causes the wedge-shaped cam 50a to rotate counterclockwise to fill the gap. The wedge-shaped cam 50 rotates counterclockwise so as to slide together with the rotary shaft 30 and the U-shaped ring 40. It should be noted that the wedge-shaped cam 50 can also be rotated clockwise in the same manner.

[0038] The reclining device 100 thus manufactured is in a state in which the U-shaped ring 40 is in contact with most of the outer surface 14a of the cylindrical boss 14 (generally 80% or more of the outer surface 14a), which stabilizes the sliding and ensures smooth rotation during sliding, and since the wedge-shaped cam 50 urges the external gear 10 to move in an eccentric direction relative to the internal gear 20, it is possible to prevent rattling when in the locked state.

[0039] In the third embodiment, similarly to the second embodiment, a substantially U-shaped bushing 90 may be provided on the convex surface 52 (outer surface) side of the wedge-shaped cam 50.

[0040] The present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention. [Industrial Applicability]

[0041] As shown in the above-described embodiment, the present invention is industrially applicable mainly as a reclining device for a vehicle seat. [Explanation of symbols]

[0042] 10...externally toothed gear, 10b...front surface, 11...external teeth, 12...through hole, 12a...inner peripheral surface, 13...protrusion, 14...cylindrical boss, 14a...outer peripheral surface, 20...internal gear, 21...internal teeth, 22...cylindrical boss, 22a...outer peripheral surface, 23...protrusion, 25...through hole, 25a...inner peripheral surface, 30...rotating shaft, 31...serration, 32...pressed extension portion, 32a...inner surface, 40...U-shaped ring, 41...outer peripheral surface, 42...inner peripheral surface, 43...through hole for elastic body, 50...wedge-shaped cam, 50a...wedge-shaped cam, 50b...wedge-shaped cam, 51...concave surface, 52...convex surface, 53...proximal end, 54...remote end, 60...spring, 61...annular portion, 62a, 62b ...end portion, 70...spring cover, 71...protrusion portion, 80...plate cover, 90...bush, 91a, 91b...bush end portion, 100...recliner device, 200...vehicle seat, 210...seat cushion, 220...seat back, 230...mounting plate,

Claims

1. A seat reclining device that tiltably holds a seat back frame that constitutes a seat back relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having external teeth formed on an outer peripheral surface and a through hole formed coaxially with the axial direction on an inner peripheral surface; an internal gear attached directly or indirectly to the other of the seat cushion frame and the seat back frame, the internal gear having internal teeth on an inner circumferential surface that are capable of meshing with the external teeth, the internal teeth being at least one more than the external teeth, and the internal gear having a cylindrical boss formed coaxially with the axial direction; a U-shaped ring disposed between the inner periphery of the through hole of the external gear and the outer periphery of the cylindrical boss of the internal gear, the center of the circularly formed outer periphery and the center of the circularly formed inner periphery being eccentric, and the U-shaped ring having an elastic body through hole formed therein; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the internal gear, that extends to an open portion of the U-shaped ring, and that has a pressing extension that presses the U-shaped ring; a substantially U-shaped bushing that is disposed on the back side of the U-shaped ring and that is provided so as to come into contact with an inner peripheral surface of a through hole of the external gear; a pair of wedge-shaped cams that are arranged on the back side of the U-shaped ring and that restrict relative rotation between the external gear and the internal gear by contacting the outer circumferential surface of the cylindrical boss of the internal gear with the inner circumferential surface of the bushing, and that allow relative rotation between the external gear and the internal gear by rotating the rotating shaft and sliding the bushing against the cylindrical boss of the internal gear or the bushing against the inner circumferential surface of the through hole of the external gear; and an elastic body that biases the pair of wedge-shaped cams in directions separating them from each other via the elastic body through-holes of the U-shaped ring.

2. A seat reclining device that tiltably holds a seat back frame that constitutes a seat back relative to a seat cushion frame that constitutes a seat cushion, an externally toothed gear attached directly or indirectly to one of the seat cushion frame and the seat back frame, the externally toothed gear having external teeth formed on an outer peripheral surface and a cylindrical boss formed coaxially with the axial direction on an inner peripheral surface; an internal gear attached directly or indirectly to the other of the seat cushion frame and the seat back frame, the internal gear having internal teeth on an inner circumferential surface that are capable of meshing with the external teeth, the internal teeth being at least one more than the external teeth, and having a through hole formed therein that is coaxial with the axial direction; a U-shaped ring disposed between the inner periphery of the through hole of the internal gear and the outer periphery of the cylindrical boss of the external gear, the center of the outer periphery surface formed in a circle and the center of the inner periphery surface formed in a circle being eccentric, and the U-shaped ring having an elastic body through hole formed therein; a rotating shaft that is coaxially and rotatably inserted into the cylindrical boss of the external gear, that extends into the open portion of the U-shaped ring, and that has a pressing extension that presses the U-shaped ring; a substantially U-shaped bushing disposed on a back surface side of the U-shaped ring and provided so as to come into contact with an inner peripheral surface of a through hole of the internal gear; a pair of wedge-shaped cams that are arranged on the back side of the U-shaped ring and that restrict relative rotation between the external gear and the internal gear by contacting the outer circumferential surface of the cylindrical boss of the external gear with the inner circumferential surface of the bushing, and that allow relative rotation between the external gear and the internal gear by rotating the rotating shaft and sliding the bushing and the cylindrical boss of the external gear or the bushing and the inner circumferential surface of the through hole of the internal gear; and an elastic body that biases the pair of wedge-shaped cams in directions separating them from each other via the elastic body through-holes of the U-shaped ring.

Images