Gear system for vehicle seats

Abstract

An example of a gear system capable of suppressing increased rotational resistance is disclosed. [Solution] On the side opposite the cage 16, with the planetary gear 15 in between, there is a sliding contact portion 20 that can slide against only a portion of the side surface of the planetary gear 15. As a result, the sliding contact portion 20 in the gear device 5 functions as a thrust bearing that restricts the displacement of the planetary gear 15 in the axial direction. Furthermore, since the sliding contact portion 20 can slide against only a portion of the side surface of the planetary gear 15, the rotational resistance of the planetary gear 15 can be reduced in the gear device 5 compared to a configuration in which the sliding contact portion 20 contacts the entire side surface of the planetary gear 15.

Description

Technical Field

[0001] The present disclosure relates to a gear device that transmits rotational force to a movable part of a vehicle seat.

Background Art

[0002] For example, in the planetary gear device described in Patent Document 1, it includes a sun gear, an internal gear, a planetary gear that meshes with the sun gear and the internal gear, and a carrier plate (also referred to as a "retainer") that holds the planetary gear. An annular protrusion is provided on the inner peripheral side of the contact surface between the side surface of the planetary gear and the carrier plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to regulate the axial direction (also referred to as the "thrust direction") load and displacement acting on the gear, if a thrust bearing that makes sliding contact over the entire axial end face of the gear is provided, the rotational resistance may increase. In view of the above points, the present disclosure discloses an example of a gear device capable of suppressing an increase in rotational resistance.

Means for Solving the Problems

[0005] The gear device that transmits rotational force to the movable part of the vehicle seat preferably includes at least one of the following constituent requirements, for example. In other words, the constituent elements are a sun gear (14) to which the driving force of an electric motor (3) is input, a planetary gear (15) that rotates on its own axis while meshing with the sun gear (14) and revolves and rotates around the sun gear (14), a cage (16) that supports the planetary gear (15) so that it can rotate on its own axis and supports the planetary gear (15) so that it can revolve around the sun gear (14), the cage (16) being rotatably arranged coaxially with the rotational axis of the sun gear (14), an output shaft (18) that rotates by obtaining rotational force from the cage (16), an internal gear (17) that meshes with the planetary gear (15), and a sliding contact portion (20) that is arranged on the opposite side of the cage (16) with the planetary gear (15) in between, and is capable of sliding contact with only a part of the side surface of the planetary gear (15), the sliding contact portion (20) being an annular sliding contact portion (20) centered on the rotational axis of the sun gear (14).

[0006] As a result, the sliding contact portion (20) in the gear device functions as a thrust bearing that restricts the axial displacement of the planetary gear (15). Furthermore, since the sliding contact portion (20) can only slide against a portion of the side surface of the planetary gear (15), the rotational resistance of the planetary gear (15) can be reduced in this gear device compared to a configuration in which the sliding contact portion (20) contacts the entire side surface of the planetary gear (15).

[0007] The gear mechanism may have, for example, the following configuration. In other words, on the planetary gear (15) opposite the cage (16), there is a boss portion (15B) that protrudes toward the sliding contact portion (20), and it is desirable that the central axis of the boss portion (15B) coincides with the rotational centerline of the planetary gear (15), and that the sliding contact portion (20) is capable of sliding contact only with a portion of the tip surface (15C) of the boss portion (15B). Furthermore, it is desirable that the sliding contact portion (20) is composed of a ridge that protrudes toward the planetary gear (15).

[0008] Furthermore, the retainer (16) is provided with a convex shaft portion (16A) that fits into a shaft hole (15A) located at the rotation center of the planetary gear (15), and it is desirable that the planetary gear (15) is prevented from falling out of the shaft portion (16A) while being held between the retainer (16) and the sliding contact portion (20).

[0009] Furthermore, the sliding contact portion (20) is configured to have at least a first protrusion (21) and a second protrusion (22) arranged concentrically, and it is desirable that the first protrusion (21) is located on the opposite side from the second protrusion (22) across the trajectory traced by the rotation center of the planetary gear (15). This makes it possible to suppress a large tilt in the orientation of the planetary gear (15) in the gear device.

[0010] Furthermore, the gear system includes a worm (11) that is rotationally driven by an electric motor (3), and a worm wheel (12) that meshes with the worm (11), which is arranged coaxially with the sun gear (14) and connected to the sun gear (14), and it is preferable that the sliding contact portion (20) is provided on the side surface of the worm wheel (12).

[0011] In this gear system, the direction of rotation of the worm wheel (12) and the direction of rotation of the planetary gear (15) are opposite. That is, if we consider a virtual circle with the orbital (rotation) center, i.e., the rotation center of the sun gear (14), as the center and passing through the rotation center of the planetary gear (15), the relative velocity of the planetary gear (15) with respect to the sliding contact portion (20) differs significantly between one side and the other side of the virtual circle.

[0012] In contrast, since the sliding contact portion (20) of the gear device can only slide in contact with a portion of the side surface of the planetary gear (15), the rotational resistance of the planetary gear (15) can be reduced compared to a configuration in which the entire side surface of the planetary gear (15) slides in contact with the side surface of the worm wheel (12).

[0013] Incidentally, the symbols in each of the parentheses above are just examples showing the correspondence with the specific configurations etc. described in the embodiments described later, and this disclosure is not limited to the specific configurations etc. indicated by the symbols in the parentheses above. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram showing an electric actuator according to the first embodiment. [Figure 2] This is a diagram showing the structure of a gear mechanism according to the first embodiment. [Figure 3] This is a diagram showing the structure of a gear mechanism according to the first embodiment. [Figure 4] This is a diagram showing the structure of a gear mechanism according to the first embodiment. [Figure 5] This is a diagram showing the structure of a gear mechanism according to the first embodiment. [Figure 6] This is a diagram showing the structure of a gear mechanism according to the first embodiment. [Figure 7] This is a diagram showing a worm wheel according to the first embodiment. [Modes for carrying out the invention]

[0015] The following "Embodiments of the Invention" are examples of embodiments that fall within the technical scope of this disclosure. In other words, the features defining the invention as described in the claims are not limited to the specific configurations and structures shown in the embodiments below.

[0016] This embodiment is an example in which the gear device for a vehicle seat according to this disclosure (hereinafter referred to as the gear device) is applied to a seat mounted on a vehicle or other vehicle (hereinafter referred to as the vehicle seat). The arrows and diagonal lines indicating direction in each figure are included to facilitate understanding of the relationships between the figures and the shapes of the members or parts.

[0017] Therefore, the gear device is not limited to the directions shown in the respective figures. The directions shown in the respective figures are the directions in the state where the vehicle seat according to the present embodiment is assembled to the vehicle. The figures with slashes do not necessarily show cross-sectional views.

[0018] At least the members or parts described with reference numerals are provided with at least one, unless otherwise specified such as "one". That is, when there is no such specification as "one", two or more of such members may be provided. The gear device disclosed herein includes at least one of the components such as the members or parts described with reference numerals and the structural parts shown in the drawings.

[0019] (First Embodiment) <1. Outline of Gear Device> The gear device according to the present embodiment is applied to the electric actuator 1 shown in FIG. 1. The electric actuator 1 is an integrated unit of an electric motor 3 and a gear device 5. The electric motor 3 is a drive source that generates a rotational force.

[0020] The gear device 5 according to the present embodiment constitutes a speed reducer. Then, the gear device 5 decelerates and transmits the rotational force of the electric motor 3 to the movable part of the vehicle seat. The movable part of the vehicle seat is, for example, a lifter link that raises and lowers the seat body or a tilt arm that raises and lowers the front end side of the seat cushion.

[0021] <2. Schematic Configuration of Gear Device> As shown in FIG. 2, the gear device 5 includes a gear casing 7, a gear mechanism 10, and the like. The gear casing 7 is a casing that houses the gear mechanism 10. The electric motor 3 is fixed to the gear casing 7 with bolts (not shown).

[0022] The gear casing 7 includes at least a casing body 71 and a casing cover 72. The casing body 71 and the casing cover 72 are fastened and secured to each other by a plurality of bolts (two in this embodiment) (not shown).

[0023] <2.1 Gear Mechanism Configuration> As shown in Figure 3, the gear mechanism 10 is composed of at least a worm 11, a worm wheel 12, and a planetary gear mechanism 13. The worm 11 is a male screw-shaped gear fixed to the output shaft (not shown) of the electric motor 3.

[0024] The worm wheel 12 is a gear that rotates in mesh with the worm 11. The worm wheel 12 is a helical gear in which the tooth trace direction is inclined with respect to the rotational axis Lo (see Figure 2).

[0025] <Planetary gear mechanism> As shown in Figure 4, the planetary gear mechanism 13 is composed of at least a sun gear 14, planetary gears 15, a cage 16, and an internal gear 17 (see Figure 3). The sun gear 14 is the gear to which the driving force of the electric motor 3 is input.

[0026] Specifically, the sun gear 14 is positioned coaxially with the worm wheel 12 and connected to the worm wheel 12. Therefore, the sun gear 14 rotates integrally with the worm wheel 12.

[0027] As shown in Figure 5, the sun gear 14 is provided with a fitting portion 14A that engages with the worm wheel 12. This fitting portion 14A is fitted into a fitting hole 12A (see Figure 7) provided in the worm wheel 12.

[0028] The worm wheel 12 and the sun gear 14 are rotatably supported on the orbital axis 19. The orbital axis 19 is supported and fixed to the casing body 71. Incidentally, the fitting portion 14A and the fitting hole 12A according to this embodiment are configured in a gear shape (see Figures 3 and 6).

[0029] As shown in Figures 3 to 5, the planetary gear 15 is a gear that rotates on its own axis while meshing with the sun gear 14, and revolves and rotates around the sun gear 14. In this embodiment, multiple (specifically, three) planetary gears 15 are provided.

[0030] The three planetary gears 15 are all congruent. Therefore, when "planetary gear 15" is mentioned below, it refers to either all three planetary gears 15 collectively or to any one of the planetary gears 15.

[0031] The retainer 16 is a carrier that supports the planetary gear 15 so that it can rotate on its own axis and also supports the planetary gear 15 so that it can revolve around the sun gear 14. The retainer 16 is rotatably positioned coaxially with the rotational axis Lo of the sun gear 14.

[0032] As shown in Figure 5, a shaft hole 15A is provided at the rotation center of the planetary gear 15. The shaft hole 15A is a through hole that penetrates the planetary gear 15 along the rotation center axis L1 of the planetary gear 15. The retainer 16 is provided with a convex shaft portion 16A that fits into the shaft hole 15A.

[0033] As a result, the planetary gear 15 can rotate on its own axis L1 while revolving and orbiting around the sun gear 14's rotation axis Lo. The cage 16 is provided with an output shaft 18 (see Figure 4). As a result, the output shaft 18 rotates by obtaining rotational force from the cage 16.

[0034] As shown in Figure 3, the internal gear 17 is a ring-shaped gear that meshes with the planetary gear 15. In this embodiment, the internal gear 17 is integrally molded with the inner wall of the casing cover 72 and is configured as an integrated part with the casing cover 72.

[0035] <Support structure for planetary gears> On the side opposite the cage 16, with the planetary gear 15 in between, a sliding contact portion 20 is provided, as shown in Figure 6. The sliding contact portion 20 is a part that can slide-contact only a portion of the side surface of the planetary gear 15. The sliding contact portion 20 is configured in an annular shape centered on the rotational axis Lo of the sun gear 14 (see Figure 7).

[0036] Specifically, a boss portion 15B is provided on the planetary gear 15 opposite the cage 16 (the lower side of the planetary gear 15 in Figure 6). The boss portion 15B is a cylindrical protrusion that projects toward the sliding contact portion 20 side (the lower side in Figure 6). The central axis of the boss portion 15B coincides with the rotational axis L1 of the planetary gear 15.

[0037] The sliding contact portion 20 is capable of sliding contact only with a portion of the tip surface 15C of the boss portion 15B (the lower end surface of the boss portion 15B in Figure 6). Furthermore, the sliding contact portion 20 according to this embodiment is composed of a ridge that protrudes toward the planetary gear 15 side.

[0038] Specifically, the sliding contact portion 20 is configured to have at least a first protrusion 21 and a second protrusion 22 arranged concentrically (see Figure 7). The first protrusion 21 is located on the opposite side of the trajectory traced by the rotation center of the planetary gear 15 from the second protrusion 22.

[0039] Furthermore, the "trajectory traced by the rotation center of the planetary gear 15" is a circle that passes through the rotation center of the sun gear 14, with the rotation center of the sun gear 14 as the center of rotation. The first protrusion 21 is located inside this circle, and the second protrusion 22 is located outside this circle.

[0040] As shown in Figure 6, the planetary gear 15 is held in place by the retainer 16 and the sliding contact portion 20, preventing it from falling off the shaft portion 16A of the retainer 16. In this embodiment, the sliding contact portion 20 is provided on the side surface of the worm wheel 12, as shown in Figure 7.

[0041] <3. Features of the gear apparatus according to this embodiment> On the side opposite the cage 16, with the planetary gear 15 in between, there is a sliding contact portion 20 that can slide against only a portion of the side surface of the planetary gear 15. As a result, the sliding contact portion 20 in the gear device 5 functions as a thrust bearing that restricts the axial displacement of the planetary gear 15.

[0042] Furthermore, since the sliding contact portion 20 can only slide-contact a portion of the side surface of the planetary gear 15, the rotational resistance of the planetary gear 15 can be reduced in the gear device 5 compared to a configuration in which the sliding contact portion 20 contacts the entire side surface of the planetary gear 15.

[0043] Incidentally, if the sliding contact portion 20 is configured to contact the entire side surface of the planetary gear 15, then the sliding contact surface of the sliding contact portion 20 will inevitably have to have a large surface area. Also, in this embodiment, the worm wheel 12 including the sliding contact portion 20 is made of resin by injection molding.

[0044] Furthermore, when molding a sliding surface with a large area using resin molding, it is difficult to ensure high flatness. In addition, since the ejector pin of the injection molding machine must be set to a part corresponding to the side of the worm wheel 12, it is difficult to mold a sliding surface with a large area using resin molding.

[0045] In contrast, in this embodiment, the sliding contact portion 20 slides against only a part of the side surface of the planetary gear 15, making it possible to reduce the sliding contact surface. Therefore, the degree of freedom in the placement of the ejector pin is increased, and the flatness of the sliding contact surface can be improved.

[0046] Furthermore, of the first protrusion 21 and the second protrusion 22 that constitute the sliding contact portion 20, the first protrusion 21 is located on the opposite side from the second protrusion 22, with the trajectory traced by the rotation center of the planetary gear 15 in between. As a result, the gear mechanism 5 makes it possible to reduce the size of the sliding contact surfaces of the first protrusion 21 and the second protrusion 22, and even if the sliding contact surfaces are reduced in size, it is possible to suppress a large tilt in the orientation of the planetary gear 15.

[0047] In this embodiment, the sliding contact portion 20 is provided on the side surface of the worm wheel 12. Furthermore, the direction of rotation of the worm wheel 12 and the direction of the planetary gear 15 are opposite.

[0048] Therefore, when a virtual circle is defined as having the orbital center as its center and passing through the rotational center of the planetary gear 15, the relative velocity of the planetary gear 15 with respect to the sliding contact portion 20 differs significantly between one side and the other side of the virtual circle.

[0049] In contrast, since the sliding contact portion 20 of the gear device 5 can only slide in contact with a part of the side surface of the planetary gear 15, the rotational resistance of the planetary gear 15 can be reduced compared to a configuration in which the entire side surface of the planetary gear 15 slides in contact with the side surface of the worm wheel 12.

[0050] (Other embodiments) In the embodiment described above, the internal gear 17 was integrally formed with the inner wall of the casing cover 72. However, this disclosure is not limited thereto. That is, for example, the internal gear 17 may be formed separately from the casing cover 72 using a different material.

[0051] The sliding contact portion 20 in the above-described embodiment was composed of a protrusion projecting toward the planetary gear 15. However, the disclosure is not limited thereto. That is, the disclosure may have, for example, the following configuration.

[0052] In other words, the disclosure may be "a configuration in which an annular groove is provided on the side surface of the worm wheel 12, and the opening edge of the groove functions as a sliding contact portion 20", or "a configuration in which the sliding contact portion 20 is a simple plane, and a projection is provided on the boss portion 15B that slides into contact with the sliding contact portion 20, or a groove is provided on the tip surface 15C of the boss portion 15B".

[0053] The sliding contact portion 20 according to the above embodiment was configured to have a first protrusion 21 and a second protrusion 22. However, the disclosure is not limited thereto. That is, the disclosure may, for example, configure the sliding contact portion 20 with a single protrusion.

[0054] In the embodiment described above, the sliding contact portion 20 was configured to slide in contact with only a portion of the tip surface 15C of the boss portion 15B. However, the disclosure is not limited thereto. That is, the disclosure may also be configured such that the sliding contact portion 20 slides in contact with a portion other than the boss portion 15B.

[0055] The sliding contact portion 20 according to the above embodiment was provided on the side surface of the worm wheel 12. However, the disclosure is not limited thereto. In the embodiments described above, the vehicle seat according to this disclosure was applied to a vehicle. However, the application of the invention disclosed herein is not limited to this. That is, the disclosure can be applied, for example, to seats used in vehicles such as railway cars, ships and aircraft, as well as to stationary seats used in theaters, homes, etc.

[0056] Furthermore, this disclosure is not limited to the embodiments described above, but is sufficient to be consistent with the intent of the disclosures described in the embodiments described above. Therefore, it may be a configuration in which at least two of the embodiments described above are combined, or a configuration in which any of the illustrated components or components described with reference numerals in the embodiments described above are omitted. [Explanation of symbols]

[0057] 1… Electric actuator 3… Electric motor 5… Gear mechanism 7… Gear casing 10… Gear mechanism 11… Worm 12… Worm wheel 12A… Mating hole 13… Planetary gear mechanism 14… Sun gear 14A… Mating part 15… Planetary gear 15A… Shaft hole 15B… Boss section 15C… Tip surface 16… Retainer 16A… Shaft section 17… Internal gear 18… Output shaft 19… Orbital shaft 20… Sliding contact part 21… First protrusion 22… Second protrusion 71… Casing body 72… Casing cover

Claims

1. In a gear system that transmits rotational force to the movable part of a vehicle seat, The sun gear receives the driving force of the electric motor, A planetary gear that rotates while meshing with the aforementioned sun gear, and revolves and rotates around the sun gear, A retainer that supports the planetary gear so that it can rotate and supports the planetary gear so that it can revolve around the sun gear, the retainer being rotatably arranged coaxially with the rotational axis of the sun gear, An internal gear that meshes with the aforementioned planetary gear, An output shaft that rotates by obtaining rotational force from the aforementioned retainer, A sliding contact portion provided on the opposite side of the retainer from the planetary gear, which is capable of sliding contact only a portion of the side surface of the planetary gear, and having an annular sliding contact portion centered on the rotational axis of the sun gear A gear mechanism equipped with a gear system.

2. On the planetary gear opposite the retainer, there is a boss portion that protrudes toward the sliding contact portion, and whose central axis coincides with the rotational centerline of the planetary gear. Furthermore, the gear device according to claim 1, wherein the sliding contact portion is capable of sliding contact only with a portion of the tip surface of the boss portion.

3. The gear apparatus according to claim 2, wherein the sliding contact portion is configured with a protrusion that extends toward the planetary gear side.

4. The retainer is provided with a convex shaft portion that fits into a shaft hole located at the rotation center of the planetary gear. Furthermore, the gear apparatus according to claim 3, wherein the planetary gear is prevented from falling off the shaft while being held between the retainer and the sliding contact portion.

5. The sliding contact portion is configured to have at least a first protrusion and a second protrusion arranged concentrically, Furthermore, the gear apparatus according to claim 4, wherein the first protrusion is located on the opposite side from the second protrusion, straddling the trajectory traced by the rotation center of the planetary gear.

6. A worm gear that is driven by an electric motor, A worm wheel that meshes with the worm, comprising a worm wheel arranged coaxially with the sun gear and connected to the sun gear, The gear apparatus according to any one of claims 1 to 5, wherein the sliding contact portion is provided on the side surface of the worm wheel.

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