Gear damper and gear structure

Abstract

To generate damage or deterioration caused by shear deformation of an elastic body when a prying load acts on a gear damper.SOLUTION: A gear damper 200 comprises an inner ring 20, an outer ring 40, and a rubber elastic body 30. The inner ring 20 includes a first cylindrical part 21 and a first flange part 22 protruding radially from an outer peripheral surface of the first cylindrical part 21. The outer ring 40 includes a second cylindrical part 41 arranged outside the outer peripheral surface of the first cylindrical part 21, and an outer peripheral surface of the second cylindrical part 41 is in contact with an inner peripheral surface of a housing 50. The rubber elastic body 30 includes a first portion 31 located between the outer peripheral surface of the first cylindrical part 21 and an inner peripheral surface of the second cylindrical part 41, and a second portion 32 located between the first flange part 22 and the housing 50.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gear damper and a gear structure. [Background technology]

[0002] For example, gear dampers are installed in transfer cases and the like in vehicles such as automobiles to reduce vibrations and suppress gear rattle noise. Patent Document 1, an example of prior art, discloses a gear damper configuration in which an elastic body such as rubber is interposed between a boss and a gear ring concentrically arranged on the outer periphery of the boss, and the elastic body is pressed against the opposing circumferential surfaces of the boss and the gear ring with a predetermined compression allowance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 63-178654 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a load in the prying direction acts on the gear damper, the axial load causes shear deformation of the elastic body, which may lead to damage to the elastic body. In consideration of the above circumstances, one aspect of the present disclosure aims to suppress shear deformation of the elastic body caused by a load in the prying direction while maintaining vibration-damping performance. [Means for solving the problem]

[0005] In order to solve the above problems, a gear damper according to one embodiment of the present disclosure comprises an inner ring, an outer ring, and a rubber elastic body, wherein the inner ring includes a first cylindrical portion and a first flange portion protruding radially from the outer peripheral surface of the first cylindrical portion, the outer ring includes a second cylindrical portion arranged outside the outer peripheral surface of the first cylindrical portion, the outer peripheral surface of the second cylindrical portion contacts the inner peripheral surface of the housing, and the rubber elastic body includes a first portion located between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion, and a second portion located between the first flange portion and the housing.

[0006] Furthermore, a gear structure according to one embodiment of the present disclosure includes a shaft, a housing, and a gear damper, wherein the gear damper has an inner ring, an outer ring, and a rubber elastic body, wherein the inner ring includes a first cylindrical portion and a first flange portion protruding radially from the outer peripheral surface of the first cylindrical portion, the outer ring includes a second cylindrical portion arranged outside the outer peripheral surface of the first cylindrical portion, the outer peripheral surface of the second cylindrical portion contacts the inner peripheral surface of the housing, and the rubber elastic body includes a first portion located between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion, and a second portion located between the first flange portion and the housing. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view showing a plane parallel to the axis of the gear structure according to the embodiment. [Figure 2] FIG. 2 is a plan view showing a plane perpendicular to the axis of the gear structure according to the embodiment. [Figure 3] FIG. 10 is a cross-sectional view showing a plane parallel to the axis of a gear structure in a comparative example. [Figure 4] FIG. 10 is a cross-sectional view showing a plane parallel to the axis of a gear structure in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] The embodiments for carrying out the present disclosure will be described with reference to the drawings. Note that the dimensions and scale of each element in each drawing may differ from those of the actual product. Furthermore, the embodiment described below is an exemplary embodiment that may be envisioned when carrying out the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiment described below.

[0009] A: Embodiment Fig. 1 is a cross-sectional view of a gear structure 100 according to an embodiment of the present disclosure. The gear structure 100 is used in a drive mechanism (e.g., a transmission or a differential) that transmits power generated by a power source such as an internal combustion engine or an electric motor in a moving body such as an automobile. As illustrated in Fig. 1, the gear structure 100 includes a shaft 10, a gear damper 200, a housing 50, and a helical gear 60.

[0010] The shaft 10 is a rotating body centered on the rotation axis X. In the following description, the direction along the rotation axis X will be referred to as the axial direction. The axial direction is divided into the Z1 direction and the Z2 direction. The Z1 direction is one direction along the rotation axis X, and the Z2 direction is the direction opposite to the Z1 direction. Furthermore, the direction along the circumference of an imaginary circle of any diameter centered on the rotation axis X will be referred to as the circumferential direction, and the direction of the radius of the imaginary circle will be referred to as the "radial direction." In the radial direction, the direction toward the rotation axis X will be referred to as the "inner side," and the direction away from the rotation axis X will be referred to as the "outer side."

[0011] 2 is a plan view of the gear structure 100 as viewed in the axial direction. As illustrated in FIGS. 1 and 2, the housing 50 is an annular structure located on the outside of the shaft 10. The housing 50 is disposed coaxially with the shaft 10. Because the inner diameter of the housing 50 is larger than the outer diameter of the shaft 10, an annular gap exists between the housing 50 and the shaft 10.

[0012] The helical gear 60 is a structure located outside the housing 50. The helical gear 60 is arranged coaxially with the shaft 10. The inner peripheral surface of the helical gear 60 surrounds the outer peripheral surface of the housing 50. The helical gear 60 is a gear in which the tooth traces of the multiple teeth arranged in the circumferential direction are inclined at a predetermined angle with respect to the rotation axis X. Note that the helical gear 60 and the housing 50 may be provided integrally.

[0013] The gear damper 200 is an annular vibration-isolating device located in the annular gap between the housing 50 and the shaft 10. The gear damper 200 is arranged coaxially with the shaft 10. The gear damper 200 includes an inner ring 20 located closer to the shaft 10, an outer ring 40 located closer to the housing 50, and a rubber elastic body 30 between the inner ring 20 and the outer ring 40.

[0014] The inner ring 20 is an annular structure that surrounds the shaft 10. The inner ring 20 is disposed coaxially with the shaft 10. The inner ring 20 includes a first cylindrical portion 21 and a first flange portion 22.

[0015] The first cylindrical portion 21 is a cylindrical portion that is installed coaxially with the shaft 10. The inner diameter of the first cylindrical portion 21 is slightly smaller than the outer diameter of the shaft 10, and the first cylindrical portion 21 is inserted with pressure. In other words, the inner circumferential surface of the first cylindrical portion 21 and the outer circumferential surface of the shaft 10 are fixed. Therefore, the inner ring 20 rotates integrally with the shaft 10 around the rotation axis X.

[0016] The first flange portion 22 is an annular portion that protrudes radially from the outer peripheral surface of the first cylindrical portion 21. Specifically, the end of the first cylindrical portion 21 in the Z1 direction protrudes at a right angle relative to the outer peripheral surface of the first flange portion 22. However, the angle at which the first flange portion 22 protrudes relative to the outer peripheral surface is not limited to a right angle. Because the first flange portion 22 is located further in the Z1 direction than the housing 50, a gap exists between the first flange portion 22 and the housing 50.

[0017] 1, the axial length of the first cylindrical portion 21 is greater than the radial length of the first flange portion 22. However, the relationship between the axial length of the first cylindrical portion 21 and the radial length of the first flange portion 22 is not limited to the above example. For example, a configuration in which the length of the first cylindrical portion 21 is less than the length of the first flange portion 22, or a configuration in which the length of the first cylindrical portion 21 and the length of the first flange portion 22 are equal, is also possible.

[0018] 1, the thickness (radial dimension) of the first cylindrical portion 21 is equal to the thickness (axial dimension) of the first flange portion 22. However, the relationship between the thickness (radial dimension) of the first cylindrical portion 21 and the thickness (axial dimension) of the first flange portion 22 is not limited to the above example. For example, a configuration in which the thickness (radial dimension) of the first cylindrical portion 21 exceeds the thickness (axial dimension) of the first flange portion 22, or a configuration in which the thickness (radial dimension) of the first cylindrical portion 21 is smaller than the thickness (axial dimension) of the first flange portion 22, is also possible.

[0019] A metal material (or a resin material) having higher rigidity than an elastic body can be used as the material for the inner ring 20. Examples of materials that can be used for the inner ring 20 include stainless steel, SPCC (Steel Plate Cold Commercial), and SPHC (Steel Plate Hot Commercial). The inner ring 20 can be manufactured by any method, but may be formed, for example, by pressing a plate-shaped member that has been formed into an annular shape.

[0020] The outer ring 40 is an annular structure disposed on the outside of the outer peripheral surface of the first cylindrical portion 21. The outer ring 40 is disposed coaxially with the shaft 10. The outer ring 40 includes a second cylindrical portion 41 and a second flange portion 42.

[0021] The second cylindrical portion 41 is a cylindrical portion that is installed coaxially with the shaft 10. Because the inner diameter of the second cylindrical portion 41 exceeds the outer diameter of the first cylindrical portion 21, an annular gap exists between the second cylindrical portion 41 and the first cylindrical portion 21. Because the outer diameter of the second cylindrical portion 41 is slightly larger than the inner diameter of the housing 50, the second cylindrical portion 41 is inserted with pressure. In other words, the outer peripheral surface of the second cylindrical portion 41 and the inner peripheral surface of the housing 50 are fixed together.

[0022] The second flange portion 42 is an annular portion that protrudes radially from the outer circumferential surface of the second cylindrical portion 41. Specifically, the second flange portion 42 located at the end of the second cylindrical portion 41 in the Z1 direction protrudes at a right angle to the outer circumferential surface of the second cylindrical portion 41 in the gap between the first flange portion 22 and the housing 50. However, the angle at which the second flange portion 42 protrudes from the outer circumferential surface is not limited to a right angle.

[0023] The Z2 direction surface of the second flange portion 42 and the Z1 direction surface of the housing 50 (hereinafter referred to as "end surface 50a") are in contact with each other. On the other hand, the Z1 direction surface of the second flange portion 42 and the Z2 direction surface of the first flange portion 22 are not in contact with each other. Therefore, a gap exists between the second flange portion 42 and the first flange portion 22.

[0024] 1, the axial length of the second cylindrical portion 41 is greater than the radial length of the second flange portion 42. However, the relationship between the axial length of the second cylindrical portion 41 and the radial length of the second flange portion 42 is not limited to the above example. For example, a configuration in which the axial length of the second cylindrical portion 41 is less than the radial length of the second flange portion 42, or a configuration in which the axial length of the second cylindrical portion 41 and the radial length of the second flange portion 42 are equal to each other is also conceivable.

[0025] 1, the plate thickness (radial dimension) of the second cylindrical portion 41 is equal to the plate thickness (axial dimension) of the second flange portion 42. However, the relationship between the plate thickness (radial dimension) of the second cylindrical portion 41 and the plate thickness (axial dimension) of the second flange portion 42 is not limited to the above example. For example, a configuration in which the plate thickness (radial dimension) of the second cylindrical portion 41 exceeds the plate thickness (axial dimension) of the second flange portion 42, or a configuration in which the plate thickness (radial dimension) of the second cylindrical portion 41 is smaller than the plate thickness (axial dimension) of the second flange portion 42, is also conceivable.

[0026] A metal material (or a resin material) having higher rigidity than an elastic body can be used as the material for the outer ring 40. Examples of materials for the outer ring 40 include stainless steel, SPCC (Steel Plate Cold Commercial), and SPHC (Steel Plate Hot Commercial). The outer ring 40 can be manufactured by any method, but may be formed, for example, by pressing a plate-shaped member formed into an annular shape.

[0027] 1, the axial positions of the Z2-direction end of the first cylindrical portion 21 and the Z2-direction end of the second cylindrical portion 41 are equal. However, the axial positional relationship between the end of the first cylindrical portion 21 and the end of the second cylindrical portion 41 is not limited to the above example. A configuration in which the axial position of the end of the first cylindrical portion 21 is further in the Z1 direction than the axial position of the end of the second cylindrical portion 41, or a configuration in which the axial position of the end of the first cylindrical portion 21 is further in the Z2 direction than the axial position of the end of the second cylindrical portion 41, is also conceivable.

[0028] In FIG. 1 , the radial positions of the outer peripheral edge of the first flange portion 22 and the outer peripheral edge of the second flange portion 42 are equal. That is, the outer diameter of the first flange portion 22 and the outer diameter of the second flange portion 42 are equal. However, the radial positions of the outer peripheral edges of the first flange portion 22 and the second flange portion 42 are not limited to the above example. It is also possible to configure the outer peripheral edge of the first flange portion 22 to be radially positioned more inward than the outer peripheral edge of the second flange portion 42, or to configure the outer peripheral edge of the first flange portion 22 to be radially positioned more outward than the outer peripheral edge of the second flange portion 42. It is desirable that neither outer peripheral edge interferes with the helical gear 60.

[0029] 1, the axial length of the first cylindrical portion 21 is greater than the axial length of the second cylindrical portion 41. However, the relationship between the axial length of the first cylindrical portion 21 and the axial length of the second cylindrical portion 41 is not limited to the above example. For example, a configuration in which the axial length of the first cylindrical portion 21 is less than the axial length of the second cylindrical portion 41, or a configuration in which the axial length of the first cylindrical portion 21 and the axial length of the second cylindrical portion 41 are equal to each other is also conceivable.

[0030] 1, the radial length of the first flange portion 22 is greater than the radial length of the second flange portion 42. However, the relationship between the radial length of the first flange portion 22 and the radial length of the second flange portion 42 is not limited to the above example. For example, a configuration in which the radial length of the first flange portion 22 is less than the radial length of the second flange portion 42, or a configuration in which the radial length of the first flange portion 22 and the radial length of the second flange portion 42 are equal to each other is also possible.

[0031] 1, the angle at which the first flange portion 22 protrudes from the outer peripheral surface is equal to the angle at which the second flange portion 42 protrudes from the outer peripheral surface. However, the relationship between the angle at which the first flange portion 22 protrudes from the outer peripheral surface and the angle at which the second flange portion 42 protrudes from the outer peripheral surface is not limited to the above example. For example, a configuration in which the angle at which the first flange portion 22 protrudes from the outer peripheral surface is tilted 45 degrees in the Z1 direction with respect to the angle at which the second flange portion 42 protrudes from the outer peripheral surface is also possible.

[0032] As illustrated in FIGS. 1 and 2, the rubber elastic body 30 is an elastic body located between the inner ring 20 and the outer ring 40.

[0033] The rubber elastic body 30 may be manufactured by any method, but for example, the rubber elastic body 30 is formed by vulcanization molding, in which uncured rubber material is filled between the inner ring 20 and the outer ring 40 and crosslinked and cured.

[0034] Examples of rubber materials used for the rubber elastic body 30 include chloroprene rubber (CR), silicone rubber (SR), acrylic rubber (ACM), urethane rubber (U), polyurethane rubber (PUR), vinyl methyl silicone rubber (VMQ), ethylene propylene diene rubber (EPDM), and fluororubber (FKM).

[0035] The rubber elastic body 30 includes a first portion 31, a second portion 32, and a third portion 33. The first portion 31, the second portion 32, and the third portion 33 are integrally formed.

[0036] The first portion 31 is a portion located between the outer peripheral surface of the first cylindrical portion 21 and the inner peripheral surface of the second cylindrical portion 41. Specifically, the outer peripheral surface of the first cylindrical portion 21 and the inner peripheral surface of the first portion 31 are in contact with each other. Furthermore, the inner peripheral surface of the second cylindrical portion 41 and the outer peripheral surface of the first portion 31 are in contact with each other. A surface of the first portion 31 in the Z2 direction (hereinafter referred to as a "first exposed surface 31a") is exposed from the first cylindrical portion 21 and the second cylindrical portion 41. As shown in FIG. 1, a first groove portion 31b is formed in the first exposed surface 31a of the first portion 31.

[0037] The first exposed surface 31a is located at the same axial position as the end of the first cylindrical portion 21 and the end of the second cylindrical portion 41. However, the first exposed surface 31a may be located in the Z1 direction relative to the end of the first cylindrical portion 21 or the end of the second cylindrical portion 41.

[0038] The first groove 31b is a recess recessed in the Z1 direction relative to the first exposed surface 31a. Specifically, the first groove 31b is an annular recess formed in the first exposed surface 31a over the entire circumference of the first portion 31. The depth and width of the first groove 31b are adjusted as appropriate during design and manufacturing depending on the type of rubber material used and the magnitude of the load.

[0039] The first portion 31 expands in the axial Z2 direction by being compressed in the radial direction. The formation of the first groove portion 31b prevents a part of the first portion 31 from protruding in the Z2 direction from the space between the first cylindrical portion 21 and the second cylindrical portion 41 even when the first portion 31 is compressed in the radial direction.

[0040] The second portion 32 is located between the Z2-direction surface of the first flange portion 22 and the Z1-direction surface of the second flange portion 42. Specifically, the Z2-direction surface of the first flange portion 22 and the Z1-direction surface of the second portion 32 are in contact with each other. Furthermore, the Z1-direction surface of the second flange portion 42 and the Z2-direction surface of the second portion 32 are in contact with each other. A radially outer surface of the second portion 32 (hereinafter referred to as a "second exposed surface 32a") is exposed from the first flange portion 22 and the second flange portion 42. As shown in FIG. 1, a second groove portion 32b is formed in the second exposed surface 32a of the second portion 32.

[0041] The second exposed surface 32a is located at the same radial position as the end of the first flange portion 22 and the end of the second flange portion 42. However, the second exposed surface 32a may be located radially inward relative to the end of the first flange portion 22 or the end of the second flange portion 42.

[0042] The second groove 32b is a recess recessed radially inward relative to the second exposed surface 32a. Specifically, the second groove 32b is an annular recess formed in the second exposed surface 32a around the entire circumference of the second portion 32. The depth and width of the second groove 32b are adjusted as appropriate during design and manufacturing depending on the type of rubber material used and the magnitude of the load.

[0043] The second portion 32 expands radially outward when compressed in the axial direction. The formation of the second groove portion 32b prevents a portion of the second portion 32 from protruding radially outward from the space between the first flange portion 22 and the second flange portion 42, even when the second portion 32 is compressed in the axial direction.

[0044] The third portion 33 is a portion that connects the first portion 31 and the second portion 32. Specifically, the third portion 33 is present in a gap surrounded by the inner ring 20, the outer ring 40, the first portion 31, and the second portion 32.

[0045] 1, the thickness (radial dimension) of the first portion 31 is equal to the thickness (axial dimension) of the second portion 32. However, the relationship between the thickness (radial dimension) of the first portion 31 and the thickness (axial dimension) of the second portion 32 is not limited to the above example. For example, a configuration in which the thickness (radial dimension) of the first portion 31 exceeds the thickness (axial dimension) of the second portion 32, or a configuration in which the thickness (radial dimension) of the first portion 31 is smaller than the thickness (axial dimension) of the second portion 32, is also possible.

[0046] In the above configuration, the gear structure 100 rotates about the rotation axis X in conjunction with the rotation of the external gear (not shown) that meshes with the helical gear 60. Collisions between the teeth of the helical gear 60 and the teeth of the external gear can generate gear rattle noise. According to the configuration of the embodiment, vibrations of the helical gear 60 caused by collision with the external gear are absorbed by the rubber elastic body 30. Therefore, gear rattle noise can be suppressed.

[0047] 3 is a cross-sectional view of a gear damper having a configuration (hereinafter referred to as the "comparative example") that is compared with the embodiment described above. In the comparative example, a gear damper 200 is composed of a first cylindrical portion 21, a second cylindrical portion 41, and a rubber elastic body 30 therebetween. In other words, the comparative example has a configuration in which the first flange portion 22, the second flange portion 42, and the second portion 32 (and the third portion 33) of the rubber elastic body 30 in this embodiment are omitted.

[0048] In the comparative gear structure, when an external gear (not shown) meshing with the helical gear 60 rotates, a prying load α is transmitted from the external gear to the housing 50 via the helical gear 60. The prying load α is further transmitted from the housing 50 via the second cylindrical portion 41 to the rubber elastic body 30. The transmitted prying load α includes an axial component β and a circumferential component. Therefore, when the prying load α acts on the rubber elastic body 30, a shear stress is generated in a direction parallel to a certain surface of the rubber elastic body 30, causing the rubber elastic body 30 to slide against that surface, resulting in shear deformation of the rubber elastic body 30. This may result in damage or deterioration of the rubber elastic body 30 due to shear deformation.

[0049] 1, in this embodiment, when an external gear (not shown) meshing with the helical gear 60 rotates, a prying load α is transmitted from the external gear to the housing 50 via the helical gear 60. The prying load α is further transmitted from the housing 50 to the rubber elastic body 30 via the outer ring 40.

[0050] In contrast to the comparative example, in this embodiment, the second flange portion 42 is pressed in the Z1 direction by the axial component β of the prying load α, resulting in the axial compression of the second portion 32 of the rubber elastic body 30. That is, the axial component β of the prying load α is absorbed by the axial compression of the second portion 32. As described above, a portion of the prying load α (axial component β) is absorbed by the compression of the rubber elastic body 30, and as a result, the shear stress acting on the rubber elastic body 30 in this embodiment is reduced compared to the shear stress acting on the rubber elastic body 30 in the comparative example. In general, the load capacity of the rubber elastic body 30 during compression deformation is higher than the load capacity of the rubber elastic body 30 during shear deformation. Therefore, damage and deterioration of the rubber elastic body 30 due to the prying load α can be suppressed.

[0051] B: Modified example Specific modified embodiments that can be added to the above-described embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate within the scope of not mutually contradicting each other.

[0052] (1) In the above embodiment, a configuration in which the helical gear 60 is located outside the housing 50 has been exemplified. However, the helical gear 60 may be replaced with other types of gears, such as a spur gear or a double-helical gear. However, in a configuration in which the helical gear 60 is located outside the housing 50, a prying load α that includes an axial component β is likely to occur, as described above. Therefore, the configuration of the present disclosure in which the second portion 32 absorbs the axial component β to suppress shear deformation of the rubber elastic body 30 is particularly effective in a configuration in which the helical gear 60 is located outside the housing 50 (i.e., a configuration in which a prying load α may occur).

[0053] (2) In the above embodiment, the first flange portion 22 is connected to the end portion of the first cylindrical portion 21 in the Z1 direction, but the position of the first flange portion 22 in the axial direction is not limited to the end portion of the first cylindrical portion 21 in the Z1 direction. For example, a configuration in which the position of the first flange portion 22 is located further in the Z2 direction than the end portion of the first cylindrical portion 21 in the Z1 direction is also conceivable.

[0054] (3) In the above-described embodiment, the outer ring 40 includes the second cylindrical portion 41 and the second flange portion 42. However, as shown in FIG. 4, the second flange portion 42 may be omitted. In a configuration in which the second flange portion 42 is omitted, the end surface 50a of the housing 50 contacts the surface of the second portion 32 of the rubber elastic body 30 facing in the Z2 direction. In the above-described configuration, the axial component β of the prying load α is absorbed by compression of the second portion 32. Therefore, the same effect as that of the embodiment can be achieved with the configuration of FIG. 4.

[0055] (4) In the above embodiment, the second flange portion 42 is connected to the Z1-direction end of the second cylindrical portion 41, but the position of the second flange portion 42 in the axial direction is not limited to the Z1-direction end of the second cylindrical portion 41. For example, a configuration in which the position of the second flange portion 42 is located further in the Z2 direction than the Z1-direction end of the second cylindrical portion 41 is also conceivable.

[0056] (5) In the above embodiment, the rubber elastic body 30 includes the first portion 31, the second portion 32, and the third portion 33. However, the third portion 33 may be omitted. In a configuration in which the third portion 33 is omitted, the first portion 31 and the second portion 32 are formed independently.

[0057] (6) In the above embodiment, the first portion 31 and the second portion 32 are integrally formed from a common material. However, the first portion 31 and the second portion 32 may be formed from different materials. As described above, when a prying load α acts on the gear structure 100, the first portion 31 is mainly subjected to a circumferential component of the load α, and the second portion 32 is mainly subjected to an axial component β. As described above, a configuration in which the first portion 31 and the second portion 32 are formed from different materials is exemplified to accommodate the difference in the directional components of the load α.

[0058] (7) In the above embodiment, the first groove 31b is formed in the first exposed surface 31a of the first portion 31, but the first groove 31b may be omitted. That is, the first exposed surface 31a may be a flat surface without any irregularities. Similarly, in the above embodiment, the second groove 32b is formed in the second exposed surface 32a of the second portion 32, but the second groove 32b may be omitted. That is, the second exposed surface 32a may be a flat surface without any irregularities.

[0059] (8) The term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantive meaning. Therefore, there is no room for restrictive interpretation of the position of each element or the order of manufacture, etc., based on the term "nth."

[0060] C: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0061] A gear damper according to one aspect (aspect 1) of the present disclosure includes an inner ring, an outer ring, and a rubber elastic body. The inner ring includes a first cylindrical portion and a first flange portion protruding radially from an outer peripheral surface of the first cylindrical portion. The outer ring includes a second cylindrical portion disposed outside the outer peripheral surface of the first cylindrical portion. The outer peripheral surface of the second cylindrical portion contacts an inner peripheral surface of a housing. The rubber elastic body includes a first portion located between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion, and a second portion located between the first flange portion and the housing. In the above-described embodiment, vibrations generated in the gear damper are absorbed by the rubber elastic body, thereby suppressing gear rattle noise. In addition, the axial component of the prying load is absorbed by compression of the second portion of the rubber elastic body. This suppresses shear deformation of the rubber elastic body caused by the prying load compared to a configuration in which the rubber elastic body does not include the second portion. Therefore, damage or deterioration of the rubber elastic body caused by shear deformation is suppressed.

[0062] In a specific example (Aspect 2) of Aspect 1, the outer ring further has a second flange portion protruding radially from the outer peripheral surface of the second cylindrical portion, the second flange portion contacting the end face of the housing, and the second portion being located between the first flange portion and the second flange portion. In the above aspect, the second flange portion is located between the second portion and the housing. This prevents direct contact between the second portion and the housing. This makes it possible to reduce wear of the rubber elastic body caused by contact of the housing with the second portion.

[0063] A gear structure according to one aspect (Aspect 3) of the present disclosure includes a shaft, a housing, and a gear damper. The gear damper includes an inner ring, an outer ring, and a rubber elastic body. The inner ring includes a first cylindrical portion and a first flange portion protruding radially from the outer peripheral surface of the first cylindrical portion. The outer ring includes a second cylindrical portion disposed outside the outer peripheral surface of the first cylindrical portion. The outer peripheral surface of the second cylindrical portion contacts the inner peripheral surface of the housing. The rubber elastic body includes a first portion located between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion, and a second portion located between the first flange portion and the housing. In this aspect, vibrations generated in the gear damper are absorbed by the rubber elastic body, thereby suppressing gear rattle noise. In addition, the axial component of a prying load is absorbed by compression of the second portion of the rubber elastic body. This suppresses shear deformation of the rubber elastic body due to a prying load, compared to a configuration in which the rubber elastic body does not include the second portion. Therefore, damage or deterioration of the rubber elastic body due to shear deformation is suppressed.

[0064] A specific example of Aspect 3 (Aspect 4) further includes a second flange portion protruding radially from the outer peripheral surface of the second cylindrical portion, the second flange portion contacting the end face of the housing, and the second portion being located between the first flange portion and the second flange portion. In the above aspect, the second flange portion is located between the second portion and the housing. This prevents direct contact between the second portion and the housing. This makes it possible to reduce wear of the rubber elastic body caused by the housing contacting the second portion.

[0065] In a specific example (Aspect 5) of either Aspect 3 or Aspect 4, a helical gear is provided on the outer peripheral surface of the housing. In these aspects, a prying load is particularly likely to occur, and shear deformation due to the prying load is likely to occur in the rubber elastic body. Therefore, the present invention, in which the axial component is absorbed by compression of the second portion of the rubber elastic body, is particularly effective. [Explanation of symbols]

[0066] 100...gear structure, 200...gear damper, 10...shaft, 20...inner ring, 21...first cylindrical portion, 22...first flange portion, 30...rubber elastic body, 31...first portion, 31a...first exposed surface, 31b...first groove portion, 32...second portion, 32a...second exposed surface, 32b...second groove portion, 33...third portion, 40...outer ring, 41...second cylindrical portion, 42...second flange portion, 50...housing, 50a...end surface, 60...helical gear.

Claims

1. A gear damper including an inner ring, an outer ring, and a rubber elastic body, the inner ring includes a first cylindrical portion and a first flange portion that protrudes radially from an outer circumferential surface of the first cylindrical portion, the outer ring includes a second cylindrical portion disposed outside an outer peripheral surface of the first cylindrical portion, an outer peripheral surface of the second cylindrical portion contacts an inner peripheral surface of the housing; the rubber elastic body includes a first portion located between an outer peripheral surface of the first cylindrical portion and an inner peripheral surface of the second cylindrical portion, and a second portion located between the first flange portion and the housing, Gear damper.

2. the outer ring further includes a second flange portion protruding radially from an outer peripheral surface of the second cylindrical portion, the second flange portion contacts an end surface of the housing, The second portion is located between the first flange portion and the second flange portion. The gear damper according to claim 1 .

3. A shaft, Housing and a gear damper; The gear damper is The bearing includes an inner ring, an outer ring, and a rubber elastic body, the inner ring includes a first cylindrical portion and a first flange portion that protrudes radially from an outer circumferential surface of the first cylindrical portion, the outer ring includes a second cylindrical portion disposed outside an outer peripheral surface of the first cylindrical portion, an outer circumferential surface of the second cylindrical portion contacts an inner circumferential surface of the housing; the rubber elastic body includes a first portion located between an outer peripheral surface of the first cylindrical portion and an inner peripheral surface of the second cylindrical portion, and a second portion located between the first flange portion and the housing, Gear structure.

4. the outer ring further includes a second flange portion protruding radially from an outer peripheral surface of the second cylindrical portion, the second flange portion contacts an end surface of the housing, The second portion is located between the first flange portion and the second flange portion. The gear structure according to claim 3 .

5. A helical gear is provided on the outer circumferential surface of the housing. The gear structure according to claim 3 or 4.

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