Gear structure

Abstract

The invention relates to a gear structure. The gear structure includes: a gear member including an outer peripheral surface provided with a plurality of gear teeth and an inner peripheral surface provided in an inward direction from the outer peripheral surface; an annular mass body provided in an inward direction from the inner peripheral surface; and an elastic body interposed between the gear member and the mass body.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority from Japanese patent application No. 2023-122301 filed on July 27, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to gear structures. Background Art

[0004] For example, a drive mechanism mounted on a movable body such as a car may have the disadvantage of emitting gear noise, such as gear rattling noise caused by the impact of the gear teeth of a plurality of gears and gear meshing noise caused by the deformation of the gear teeth. Japanese Patent Application Publication No. 2014-134230 discloses a structure in which a gear includes two annular grooves, each of which accommodates an annular elastomer for absorbing vibration. One of the two annular grooves is formed on the surface of the gear in the axial direction, and the other of the two annular grooves is formed on the surface of the gear in the direction opposite to the axial direction. However, in the structure disclosed in Japanese Patent Application Publication No. 2014-134230, since the annular groove is formed on the surface of the gear, the rigidity of the gear is reduced. As a result, there is a disadvantage that the reliability of torque transmission is reduced. In addition, vibration cannot be sufficiently damped only by the elastomer accommodated in the annular groove. Summary of the invention

[0005] An object according to one aspect of the present disclosure is to effectively reduce gear noise.

[0006] A gear structure according to one aspect of the present disclosure includes: a gear member including an outer peripheral surface provided with a plurality of gear teeth and an inner peripheral surface provided inwardly from the outer peripheral surface; an annular mass body provided inwardly from the inner peripheral surface; and an elastic body interposed between the gear member and the mass body. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a plan view of a gear mechanism according to an embodiment.

[0008] Figure 2 For along Figure 1 The cross section is taken along line II-II.

[0009] Figure 3 : is a graph which shows the frequency characteristic of the operation sound produced|generated by the operation of a gear mechanism.

[0010] Figure 4 : is a graph showing the frequency characteristics of the operation sound generated according to the operation of the gear mechanism. DETAILED DESCRIPTION

[0011] Now, embodiments according to the present disclosure will be described with reference to the accompanying drawings. In each figure, the size and ratio of the elements may be different from the size and ratio of the actual product. In addition, the embodiments described below are exemplary embodiments assumed in the case of implementing the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiments described below.

[0012] Figure 1 is a plan view of a gear mechanism 100 according to an embodiment of the present disclosure. Figure 2 is along Figure 1 The cross section is shown along line II-II. The gear mechanism 100 is used in a drive mechanism (eg, a transmission or a differential) for transmitting power from a power source such as an internal combustion engine or an electric motor to wheels in a movable body such as an automobile.

[0013] like Figure 1 and Figure 2 As shown, the gear mechanism 100 includes a shaft member 11 and a gear structure 12. The shaft member 11 is a cylindrical shaft rotatable about a rotation axis C. The gear structure 12 is a rotatable body fixed to the shaft member 11. The shaft member 11 can be understood as an element of the gear structure 12.

[0014] In the following description, it is assumed that the virtual circle has a freely selected diameter and a center set on the rotation axis C. The direction of the circumference of the virtual circle is referred to as the "circumferential direction", and the direction of the radius of the virtual circle is referred to as the "radial direction". The direction along the radial direction and toward the rotation axis C is referred to as the "inward direction". The direction along the radial direction and away from the rotation axis C is referred to as the "outward direction".

[0015] like Figure 1 and Figure 2 As shown, the gear structure 12 includes a gear member 20, a mass body 60 and an elastic body 70. Figure 1 In the figure, for convenience, shadows are added to the mass body 60 and the elastic body 70.

[0016] The gear member 20 is a disc-shaped spur gear. Specifically, the gear member 20 includes a first portion 30, a second portion 40, and a connecting portion 50. For example, the first portion 30, the second portion 40, and the connecting portion 50 are integrally formed of a material having a high mechanical strength, such as carbon steel (S45C), chrome-molybdenum alloy steel (SCM440, SCM415), and stainless steel (SUS303) for mechanical structural purposes.

[0017] The first portion 30 is an annular portion including an outer peripheral surface 31 and an inner peripheral surface 32. The first portion 30 is rotatable about the rotation axis C. The outer peripheral surface 31 is a wall surface of the first portion 30 facing in an outward direction, and the inner peripheral surface 32 is a wall surface disposed in an inward direction from the outer peripheral surface 31. Figure 1 As shown, the outer peripheral surface 31 of the first part 30 is provided with a plurality of gear teeth 21, and the gear teeth are equally spaced from each other in the circumferential direction. It can be understood from the above description that the gear member 20 is a structure including an outer peripheral surface 31 and an inner peripheral surface 32, wherein the outer peripheral surface is provided with a plurality of gear teeth 21, and the inner peripheral surface is provided inwardly from the outer peripheral surface.

[0018] like Figure 1 and Figure 2 As shown, the second part 40 is an annular part including an outer peripheral surface 41 and an inner peripheral surface 42. The second part 40 can rotate around the rotation axis C. The outer peripheral surface 41 is a wall surface of the second part 40 facing in the outward direction, and the inner peripheral surface 42 is an inner wall surface arranged in the inward direction from the outer peripheral surface 41. The outer diameter of the second part 40 is smaller than the inner diameter of the first part 30. The second part 40 is arranged in the inward direction from the first part 30. In other words, the inner peripheral surface 32 of the first part 30 faces the outer peripheral surface 41 of the second part 40 across a predetermined space.

[0019] The connecting portion 50 is an annular portion between the first portion 30 and the second portion 40. The connecting portion 50 connects the first portion 30 and the second portion 40 to each other. The thickness of the connecting portion 50 is smaller than the thickness of the first portion 30 (in the direction of the rotation axis C) and smaller than the thickness of the second portion 40. Figure 2 As shown, an annular space S surrounded by the inner peripheral surface 32 of the first portion 30 , the outer peripheral surface 41 of the second portion 40 , and the surface 51 of the connecting portion 50 is formed.

[0020] The mass body 60 and the elastic body 70 are accommodated in the space S. In other words, the mass body 60 and the elastic body 70 are interposed between the first portion 30 and the second portion 40. Figure 2 As shown, the mass body 60 and the elastic body 70 are arranged within the range of the direction of the rotation axis C, and the range of the direction of the rotation axis C is between the top surface 35 of the first part 30 and the surface 51 of the connecting part 50. Specifically, the mass body 60 and the elastic body 70 face the surface 51 of the connecting part 50 across a gap. According to the above-mentioned configuration, the probability of contact between the mass body 60 and the gear member 20 can be reduced. Therefore, the noise (click noise) caused by the contact between the mass body 60 and the gear member 20 can be substantially prevented. The elastic body 70 can be in contact with the connecting part 50.

[0021] The mass body 60 is a mass damper provided inwardly from the inner peripheral surface 32 of the gear member 20. Specifically, the mass body 60 is a structure made of a highly rigid metal material such as iron and stainless steel. The mass body 60 is annular and includes an outer peripheral surface 61 and an inner peripheral surface 62.

[0022] Specifically, the mass body 60 is a structure in which a main body 66 and a protrusion 67 are integrally formed. The main body 66 is an annular portion that is rectangular when viewed in a cross section. The main body 66 includes a bottom surface that is not in contact with the surface 51 of the connecting portion 50. However, the bottom surface of the main body 66 may be in contact with the surface 51 of the connecting portion 50. The protrusion 67 is an annular portion that protrudes from the outer peripheral edge of the main body 66 in the direction of the rotation axis C. The outer peripheral surface 61 is a wall surface extending from the main body 66 to the protrusion 67, and the inner peripheral surface 62 is a wall surface of the main body 66 facing the inward direction. According to the configuration in which the mass body 60 includes the protrusion 67, the area of ​​the outer peripheral surface 61 can be easily ensured compared to the configuration in which the mass body 60 is composed only of the main body 66.

[0023] The outer diameter of the mass body 60 is smaller than the inner diameter of the first portion 30. The outer peripheral surface 61 of the mass body 60 faces the inner peripheral surface 32 of the first portion 30 across a space. In other words, the entire circumference of the mass body 60 is surrounded by the first portion 30. The inner diameter of the mass body 60 is larger than the outer diameter of the second portion 40. The inner peripheral surface 62 of the mass body 60 faces the outer peripheral surface 41 of the second portion 40 across a space. As described above, the mass body 60 is interposed between the first portion 30 and the second portion 40 of the gear member 20.

[0024] For example, the elastic body 70 is a damping spring made of an elastic material such as rubber and resin. Specifically, the elastic body 70 is an annular structure including an outer peripheral surface 71 and an inner peripheral surface 72. The elastic body 70 is rotatable around the rotation axis C. The outer peripheral surface 71 is a wall surface of the elastic body 70 facing in an outward direction, and the inner peripheral surface 72 is an inner wall surface set in an inward direction from the outer peripheral surface 71.

[0025] The elastomer 70 is interposed between the gear member 20 and the mass body 60. Specifically, the elastomer 70 is interposed between the first portion 30 of the gear member 20 and the mass body 60. In other words, the elastomer 70 is interposed between the inner circumferential surface 32 of the gear member 20 and the outer circumferential surface 61 of the mass body 60. More specifically, the outer circumferential surface 71 of the elastomer 70 is in close contact with the inner circumferential surface 32 of the gear member 20, and the inner circumferential surface 72 of the elastomer 70 is in close contact with the outer circumferential surface 61 of the mass body 60. As described above, the gear member 20 and the mass body 60 are elastically connected to each other via the elastomer 70. Specifically, the mass body 60 is elastically connected to the first portion 30 of the gear member 20 via the elastomer 70.

[0026] In the above configuration, the mass body 60 and the elastic body 70 constitute a dynamic vibration absorber D (dynamic damper). The dynamic vibration absorber D is interposed between the first portion 30 and the second portion 40 of the gear member 20. Specifically, the dynamic vibration absorber D is connected to the inner peripheral surface 32 of the first portion 30. The dynamic vibration absorber D absorbs the vibration of the shaft member 11 and the vibration of the gear structure 12 (especially the natural vibration component in the radial direction). In other words, the movement of the shaft member 11 in the radial direction and the movement of the gear structure 12 in the radial direction can be substantially prevented. Therefore, the gear noise caused by the rotation of the gear structure 12 can be effectively reduced.

[0027] For example, when the shaft member 11 vibrates in the radial direction, the gear rattling noise becomes noticeable due to the impact of the gear teeth 21 of the gear member 20 on the gear teeth of the gear (not shown) meshing with the gear structure 12. In addition, when the shaft member 11 vibrates in the radial direction in a state where the gear structure 12 is meshed with the gear, the gear teeth 21 of the gear member 20 are deformed by the force applied to the gear teeth 21. As a result, the gear meshing noise caused by the deformation of the gear teeth 21 becomes noticeable. According to the present embodiment, the dynamic damper D composed of the mass body 60 and the elastic body 70 absorbs the natural vibration of the shaft member 11 in the radial direction and the natural vibration of the gear structure 12 in the radial direction. Therefore, gear noise, such as gear rattling noise and gear meshing noise, can be effectively reduced.

[0028] Figure 3 and Figure 4 These are graphs showing frequency characteristics of operation sounds generated according to the operation of the gear mechanism 100 . Figure 3 and Figure 4 1 and 2 show the frequency characteristics of the operation sound generated by the operation of the gear mechanism 100 according to the present embodiment, in which the dynamic damper D is provided. Figure 3 and Figure 4 Frequency characteristics of operation sounds generated according to operation of a configuration in which the dynamic damper D is not provided (hereinafter referred to as a “comparative example”) are respectively shown.

[0029] Figure 3 1 is a graph showing the frequency characteristics of the operation sound caused by the vibration of the gear mechanism 100 in the radial direction. Figure 3 It is understood that, according to this embodiment including the dynamic damper D, the peak value of the operation sound caused by each order vibration mode in the direction along the radial direction is reduced compared with the comparative example. In other words, according to this embodiment, as described above, gear noise such as gear rattling noise and gear meshing noise, which are caused by vibration in the radial direction, can be effectively reduced. As described above, the dynamic damper D according to the present embodiment is configured to reduce the vibration of the gear mechanism 100 in the radial direction.

[0030] Figure 4 FIG. 4 is a graph showing the frequency characteristics of operation sounds caused by different vibration modes. Figure 4 As shown, in the comparative example, a local peak caused by each of the different vibration modes of the gear member 20 is detected by the operation sound. Figure 4 The peak P1 shown in FIG. 1 is a component caused by a vibration mode (bending mode) in which the gear member 20 bends so that the middle position of the gear member 20 in the rotation axis C direction is different from the position of the peripheral portion of the gear member 20 in the rotation axis C direction. Figure 4 The peak value P2 shown in FIG. 1 is a component caused by a vibration mode (expansion and contraction mode) in which the gear member radially expands and contracts in a plane perpendicular to the rotation axis C. Figure 4 It is understood that, according to this embodiment including the dynamic damper D, the peak value P1 caused by the bending mode and the peak value P2 caused by the expansion and contraction mode are reduced compared to the comparative example. In other words, according to this embodiment, the gear noise caused by the bending mode and the tooth noise caused by the expansion and contraction mode can be effectively reduced. As described above, the dynamic damper D according to the present embodiment is configured to reduce the vibration of the gear member 20 in the bending mode and the vibration of the gear member 20 in the expansion and contraction mode.

[0031] In the present embodiment, the inner peripheral surface 32 of the gear member 20 is arranged in the inward direction from the outer peripheral surface 31 provided with the plurality of gear teeth 21, and the mass body 60 is elastically connected to the inner peripheral surface 32 via the elastic body 70. Specifically, the mass body 60 is elastically connected to the inner peripheral surface 32 of the first portion 30 via the elastic body 70. Therefore, compared with the configuration in which the mass body 60 is elastically connected to the second portion 40 or the connecting portion 50, the advantage of reducing gear noise is significant.

[0032] B: Deformation

[0033] Specific variations that can be applied to the above-described embodiment are described below. Two or more variations freely selected from the following variations can be combined as long as such combination does not cause a contradiction.

[0034] (1) The shape of the mass body 60 can be freely selected and is not limited to the above-mentioned examples. For example, the protrusion 67 of the mass body 60 can be omitted. The mass body 60 can be composed of a combination of a plurality of elements made of different materials.

[0035] (2) The shape of the elastic body 70 can be freely selected and is not limited to the above examples. For example, the elastic body 70 can be composed of a stack of multiple layers made of different materials. The elastic body 70 can be composed of multiple different separate elements. For example, the elastic body 70 can be composed of multiple elements arranged in the annular space between the inner circumferential surface 32 of the first part 30 and the outer circumferential surface 61 of the mass body 60, and the multiple elements are spaced apart from each other in the circumferential direction.

[0036] (3) In the above embodiment, the configuration in which the elastic body 70 is interposed between the mass body 60 and the first portion 30 is described. However, the setting position of the elastic body 70 is not limited to the above example. For example, it is assumed that the elastic body 70 is interposed between the mass body 60 and the second portion 40. Alternatively, it is assumed that the elastic body 70 is interposed between the mass body 60 and the connecting portion 50. The elastic body 70 may be interposed between the mass body 60 and each of two or more selected from the first portion 30, the second portion 40 and the connecting portion 50.

[0037] (4) In the above embodiment, the gear structure 12 is described as a spur gear. However, the present disclosure can be applied to any type of gear, such as a bevel gear and a helical gear. The purpose of the gear mechanism 100 can be freely selected and is not limited to a drive mechanism of a movable body such as an automobile.

[0038] C: Additional information

[0039] The following configurations can be derived from the aforementioned embodiments.

[0040] According to one aspect (first aspect) of the present disclosure, a gear structure includes: a gear member including an outer peripheral surface provided with a plurality of gear teeth and an inner peripheral surface provided in an inward direction from the outer peripheral surface; an annular mass body provided in an inward direction from the inner peripheral surface; and an elastic body interposed between the gear member and the mass body. According to this aspect, the mass body and the elastic body constitute a dynamic damper. The dynamic damper absorbs the vibration of the gear structure (especially the natural vibration component in the radial direction). In other words, the movement of the gear structure in the radial direction can be substantially prevented. Therefore, the gear noise caused by the rotation of the gear structure can be effectively reduced.

[0041] In a specific example of the first aspect (second aspect), the elastic body is interposed between the inner peripheral surface of the gear member and the outer peripheral surface of the mass body. According to this aspect, the mass body is elastically connected to the inner peripheral surface set inward from the outer peripheral surface provided with a plurality of gear teeth via the elastic body. Therefore, compared with a configuration in which the mass body is elastically connected to a portion other than the inner peripheral surface of the gear member, the advantage of reducing gear noise is significant.

[0042] In a specific example of the first aspect (the third aspect), the gear member includes: an annular first part including an outer peripheral surface and an inner peripheral surface; an annular second part arranged in an inward direction from the first part; and an annular connecting portion between the first part and the second part, the annular connecting portion connecting the first part and the second part to each other, a mass body between the first part and the second part, and an elastomer between the first part and the mass body. According to this aspect, the mass body is elastically connected to the inner peripheral surface of the first part provided with a plurality of gear teeth via the elastomer. Therefore, compared with the configuration in which the mass body is elastically connected to the second part, a significant advantage is that gear noise is reduced.

[0043] Description of Reference Numerals

[0044] 100…gear mechanism, 11…shaft member, 12…gear structure, 20…gear member, 21…gear teeth, 30…first portion, 31…outer peripheral surface, 32…inner peripheral surface, 40…second portion, 41…outer peripheral surface, 42…inner peripheral surface, 50…connecting portion, 51…surface, 60…mass body, 61…outer peripheral surface, 62…inner peripheral surface, 66…main body, 67…protrusion, 70…elastic body, 71…outer peripheral surface, 72…inner peripheral surface, D…dynamic damper.

Claims

1. A gear structure, comprising: A gear member comprising: an outer peripheral surface provided with a plurality of gear teeth; and an inner peripheral surface disposed inwardly from the outer peripheral surface; an annular mass body disposed along the inward direction from the inner circumferential surface; and An elastic body is interposed between the gear member and the mass body.

2. The gear structure according to claim 1, wherein: The elastic body is interposed between the inner peripheral surface of the gear member and the outer peripheral surface of the mass body.

3. The gear structure according to claim 1, in, The gear member comprises: an annular first portion, comprising the outer peripheral surface and the inner peripheral surface; an annular second portion disposed in the inward direction from the first portion; and an annular connecting portion, which is interposed between the first portion and the second portion, the annular connecting portion connecting the first portion and the second portion to each other, wherein the mass body is between the first part and the second part, and Wherein, the elastic body is between the first part and the mass body.

Images