Dynamic Damper

Abstract

The purpose of the present invention is to provide a dynamic damper which, when installed in a hollow rotation shaft, facilitates achieving a uniform compression ratio of the outer periphery-side rubber part, decreases the load on a sleeve and mount rubber, and in which, when cleaning by flushing a cleaning liquid through the hollow rotation shaft, the cleaning liquid is not prone to remain therein. This dynamic damper, which is attached to the inner periphery-side of the hollow rotation shaft, is provided with an outer periphery-side rubber part which is arranged on the outer diameter side and which adheres to the inner peripheral surface of the hollow rotation shaft, a sleeve which is arranged on the inner periphery side of the outer periphery-side rubber part, an inner weight which is arranged so as to contain the rotation shaft, and a mount rubber which supports the inner weight; an outer peripheral groove is formed along the entire circumference in the center of the outer peripheral surface of the outer periphery-side rubber part, and the dynamic damper is configured such that, when attached to the inner peripheral surface of the hollow rotation shaft, the two sections of the outer peripheral surface of the outer periphery-side rubber part that are separated by an outer peripheral groove move in directions away from each other, and thereby, the two lateral surfaces of the outer periphery-side rubber part are provided with a tapered shape.

Description

[Technical field]

[0001] The present invention relates to a dynamic damper, and more particularly to a dynamic damper that is attached to the inner peripheral surface of a hollow rotating shaft, such as a propeller shaft of an automobile, to suppress vibrations and noise generated in the hollow rotating shaft. [Background technology]

[0002] Conventionally, a dynamic damper is pressed into the propeller shaft, which constitutes part of the power transmission system used in front-wheel drive or four-wheel drive automobiles, to reduce bending resonance.

[0003] A conventional dynamic damper will be described with reference to the drawings. Figure 3(a) is a side view (schematic diagram) of a conventional dynamic damper, and Figure 3(b) is a cross-sectional view (schematic diagram) of the conventional dynamic damper taken along line BB' passing through the central axis ω in Figure 3(a).

[0004] As shown in Figure 3, the dynamic damper 101 is arranged on the outer diameter side and has an outer rubber part 102 that is in close contact with the inner surface of the hollow rotating shaft, a metal sleeve 103 attached to the inner surface, a metal inner weight 104 that is arranged near the central axis of the hollow rotating shaft, and a mounting rubber 105 that is provided between the sleeve 103 and the inner weight 104 and connects them. The mount rubber 105 is usually provided with a plurality of slits 105b penetrating in the axial direction, and a plurality of connecting portions 105a connect the sleeve 103 and the inner weight 104. The inner weight 104 is supported by the connecting portions 105a of the mount rubber 105.

[0005] When the dynamic damper 101 is pressed and fixed into a hollow rotating shaft such as a propeller shaft, the dynamic damper 101 acts as a secondary vibration system, resonating in antiphase with the input vibration in a specified vibration frequency range, thereby providing a dynamic vibration absorption effect and suppressing vibrations and noise that may occur in the hollow rotating shaft such as a propeller shaft. Summary of the Invention [Problem to be solved by the invention]

[0006] When the conventional dynamic damper 101 as described above is press-fitted and fixed into a hollow rotating shaft such as a propeller shaft, the outer circumferential rubber portion 102 is compressed in the radial direction. Here, since the inner diameter of the hollow rotating shaft is not constant, it is difficult to achieve a completely uniform compression ratio at each portion of the outer circumferential rubber portion 102. If the compression ratios at each portion of the outer circumferential rubber portion 102 differ significantly, there is a risk that the vibration characteristics of the dynamic damper will not match the design values. Therefore, it is preferable that the compression ratio be as close to uniform as possible at each portion of the outer circumferential rubber portion 102. In addition, when the outer circumferential rubber portion 102 is compressed in the radial direction by being pressed into the hollow rotating shaft, a certain amount of load may also be applied to the sleeve 103 and the mount rubber 105 located inside. If this load is too large, there is a risk that the vibration characteristics of the dynamic damper will not match the design values. Therefore, it is preferable that the degree of this load is as small as possible.

[0007] Furthermore, in some cases where the inside of the hollow rotating shaft is washed, it is preferable that the washing water poured into the hollow rotating shaft does not remain inside the hollow rotating shaft after washing.

[0008] The present invention has an object to solve the above-mentioned problems, that is, to provide a dynamic damper which, when installed in a hollow rotating shaft, tends to have a uniform compression rate for each portion of the outer circumferential rubber portion, reduces the load on the sleeve and the mount rubber, and is less likely to leave cleaning liquid behind when cleaning is performed by pouring cleaning liquid into the hollow rotating shaft. [Means for solving the problem]

[0009] In order to solve the above problems, the present inventors have conducted intensive research and have completed the dynamic damper of the present invention. The dynamic damper of the present invention is a dynamic damper attached to an inner peripheral side of a hollow rotating shaft, a cylindrical outer circumferential rubber portion disposed on an outer diameter side and in close contact with an inner circumferential surface of the hollow rotating shaft; a cylindrical sleeve disposed on an inner peripheral side of the outer peripheral rubber portion; a cylindrical or columnar inner weight disposed at a position including a central axis of the hollow rotating shaft; a mount rubber provided between the sleeve and the inner weight and supporting the inner weight; having an outer circumferential groove is formed around the entire periphery of the outer circumferential surface of the outer circumferential rubber portion at a center in the central axis direction, When the outer rubber portion is attached to the inner surface of the hollow rotating shaft and compressed radially, two portions separated in the central axis direction by the outer groove on the outer surface of the outer rubber portion move away from each other in the central axis direction, so that the outer surface side of the two side surfaces of the outer rubber portion is positioned further outward in the central axis direction than the inner surface side, and the two side surfaces of the outer rubber portion are configured to have a tapered shape with an inner diameter gradually decreasing from the outer surface side toward the inner surface side. Effect of the Invention

[0010] According to the present invention, a dynamic damper can be provided which, when installed inside a hollow rotating shaft, tends to have a uniform compression rate for each part of the outer rubber portion, reducing the load on the sleeve and mount rubber, and further, when cleaning liquid is poured into the hollow rotating shaft for cleaning, is less likely to leave cleaning liquid behind afterwards. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1(a) is a side view (schematic diagram) of a dynamic damper of the present invention, and FIG. 1(b) is a cross-sectional view (schematic diagram) taken along line AA' in FIG. 1(a). [Diagram 2] 2 is a schematic cross-sectional view showing the dynamic damper of the present invention shown in FIG. 1 mounted inside a hollow rotating shaft. [Diagram 3]FIG. 3(a) is a side view of a conventional dynamic damper, and FIG. 3(b) is a cross-sectional view (schematic diagram) taken along line BB' in FIG. 3(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The dynamic damper of the present invention will now be described. The dynamic damper of the present invention is a dynamic damper that is attached to the inner peripheral side of a hollow rotating shaft and suppresses vibrations and noise generated in this hollow rotating shaft. An example of a hollow rotating shaft is a propeller shaft for an automobile.

[0013] A preferred embodiment of the dynamic damper of the present invention will be described with reference to the drawings. Figure 1(a) is a side view (schematic diagram) of the preferred embodiment of the dynamic damper of the present invention, and Figure 1(b) is a cross-sectional view (schematic diagram) of the dynamic damper taken along line AA' passing through the central axis ω in Figure 1(a). The dynamic damper of the present invention described below with reference to the drawings is a preferred embodiment, and the dynamic damper of the present invention is not limited thereto.

[0014] As shown in FIG. 1, a dynamic damper 1 of the present invention has an outer circumferential rubber portion 3, a sleeve 5, an inner weight 7, and a mount rubber 9.

[0015] <Outer rubber part> In the dynamic damper 1 of the present invention, the outer periphery side rubber portion 3 is disposed on the outermost side. The outer periphery surface of the outer periphery side rubber portion 3 is in close contact with the inner periphery surface of the hollow rotating shaft.

[0016] The outer circumferential rubber portion 3 is cylindrical, and its central axis essentially coincides with the central axis ω of the dynamic damper 1 of the present invention. 1(b), a groove is formed around the entire circumference of the outer circumferential surface of the outer rubber portion 3 in the center in the direction parallel to the central axis ω. This groove is also referred to as the outer circumferential groove 3a in the present invention. The outer circumferential surface is divided into two portions 31 and 33 in the direction parallel to the central axis ω by the outer circumferential groove 3a. The role and function of the outer circumferential groove 3a will be described in detail later.

[0017] The outer rubber portion 3 has a cylindrical shape and has an outer circumferential groove 3a as described above, but other shapes are not particularly limited. For example, it may be the same as a conventionally known shape. For example, it is preferable that the corners at the boundary between the outer circumferential surface and the side surface of the outer rubber portion 3 are rounded off to make it easier to press the dynamic damper of the present invention into the inner circumferential side of the hollow rotating shaft.

[0018] The size and material of the outer circumferential rubber portion 3 are not particularly limited and may be the same as those known in the art. Examples of the material of the outer circumferential rubber portion 3 include natural rubber (NR), ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), butadiene rubber (BR), and acrylonitrile butadiene rubber (NBR).

[0019] <Sleeve> In the dynamic damper 1 of the present invention, the sleeve 5 is disposed on the inner circumferential side of the outer circumferential rubber part 3. Although there may be something else between the sleeve 5 and the outer circumferential rubber part 3, it is preferable that the outer circumferential surface of the sleeve 5 is attached to the inner circumferential surface of the outer circumferential rubber part 3, and it is more preferable that the outer circumferential surface of the sleeve 5 and the inner circumferential surface of the outer circumferential rubber part 3 are bonded, and it is even more preferable that they are vulcanization bonded. If the outer circumferential surface of the sleeve 5 and the inner circumferential surface of the outer circumferential rubber part 3 are bonded, when the dynamic damper 1 of the present invention is attached to the inner circumferential surface of the hollow rotating shaft, the outer circumferential rubber part 3 is easily deformed into an intended shape and maintained in that shape. This will be described in detail later.

[0020] The sleeve 5 is cylindrical, and the length of the sleeve 5 in the direction parallel to the central axis ω preferably coincides with the length of the inner circumferential surface of the outer circumferential rubber portion 3 in the direction parallel to the central axis ω.

[0021] The size and material of the sleeve 5 are not particularly limited and may be the same as those known in the art. The sleeve 5 is preferably made of a material that is difficult to deform, and specifically, is preferably made of metal, for example.

[0022] <Inner weight> In the dynamic damper 1 of the present invention, the inner weight 7 is disposed at a position including the central axis ω of the hollow rotation shaft. That is, the central axis ω of the hollow rotation shaft passes through the inner weight 7. Moreover, the inner weight 7 is cylindrical or columnar, and its central axis basically coincides with the central axis ω of the hollow rotating shaft.

[0023] There are no particular limitations on the size or material of the inner weight 7, as long as it can provide the desired resonant frequency characteristics. The inner weight 7 is preferably made of, for example, metal.

[0024] <Mount rubber> In the dynamic damper 1 of the present invention, the mount rubber 9 is provided between the sleeve 5 and the inner weight 7. The mount rubber 9 supports the inner weight 7. Although there may be something else between the sleeve 5 and the inner weight 7, it is preferable that there is no other thing between the sleeve 5 and the inner weight 7 and that the mount rubber 9 connects the sleeve 5 and the inner weight 7. It is more preferable that the mount rubber 9 is bonded to the sleeve 5 and the inner weight 7, and it is even more preferable that it is bonded by vulcanization.

[0025] It is preferable that the mount rubber 9 has a plurality of slits 9b penetrating in the axial direction, and a plurality of connecting portions 9a connect the sleeve 5 and the inner weight 7. The inner weight 7 is supported by the connecting portions 9a in the mount rubber 9 and held in the vicinity of the central axis ω.

[0026] The shape, size, material, etc. of the mount rubber 9 are not particularly limited and may be the same as those known in the art. Examples of the material of the mount rubber 9 include natural rubber (NR), ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), butadiene rubber (BR), and acrylonitrile butadiene rubber (NBR).

[0027] <effect> As described above, in the dynamic damper 1 of the present invention, the outer circumferential groove 3a is formed over the entire periphery at the center in the direction of the central axis ω on the outer circumferential surface of the outer circumferential rubber portion 3. Here, the central portion means a position including the center. Therefore, the outer circumferential groove 3a includes the center in the direction of the central axis ω on the outer circumferential surface of the outer circumferential rubber portion 3. Further, the outer circumferential surface of the outer circumferential rubber portion 3 is divided into two portions 31 and 33 in a direction parallel to the central axis ω by an outer circumferential groove 3a in the outer circumferential surface.

[0028] When the dynamic damper 1 of the present invention is attached to the inner peripheral surface of a hollow rotating shaft, it becomes in the state shown in Figure 2. Figure 2 is a cross-sectional view (a cross-sectional view cut by a plane including the central axis ω) showing the state in which the dynamic damper 1 of the present invention is attached to the inner peripheral surface of a hollow rotating shaft.

[0029] 2, when the outer circumferential surface of the outer circumferential rubber part 3 of the dynamic damper 1 of the present invention is brought into close contact with the inner circumferential surface 10a of the hollow rotating shaft 10 and attached, the outer circumferential rubber part 3 is compressed in the radial direction (perpendicular to the central axis ω). At this time, two portions 31, 33 on the outer circumferential surface of the outer circumferential rubber part 3 move away from each other in a direction parallel to the central axis ω, centered on the outer circumferential groove 3a. As a result, the outer peripheral surface side 35a of one side surface 35 of the outer peripheral rubber portion 3 is positioned outwardly of the inner peripheral surface side 35b in the direction parallel to the central axis ω. Similarly, the outer peripheral surface side 37a of the other side surface 37 is positioned outwardly of the inner peripheral surface side 37b in the direction parallel to the central axis ω. As a result, the two side surfaces 35, 37 of the outer peripheral rubber portion 3 have a tapered shape in which the inner diameter gradually decreases from the outer peripheral surface sides 35a, 37a to the inner peripheral surface sides 35b, 37b.

[0030] Since the dynamic damper of the present invention has an outer peripheral groove 3 as shown in Fig. 1, when it is installed on the inner peripheral side of a hollow rotating shaft, the outer peripheral rubber part 3 deforms so that its side has a tapered shape as shown in Fig. 2. Therefore, the compression ratio of each part of the outer peripheral rubber part 3 tends to be constant, and the sleeve 5 and the mount rubber 9 are less likely to be subjected to load.

[0031] Furthermore, when the dynamic damper of the present invention is installed on the inner periphery of a hollow rotating shaft, the two side surfaces 35, 37 of the outer periphery rubber part 3 have a tapered shape as shown in Fig. 2, so that when cleaning liquid is poured into the hollow rotating shaft to clean it, the cleaning liquid is less likely to remain. In particular, cleaning liquid is likely to remain in the area of ​​the outer periphery side 35a, 37a of the side surfaces 35, 37 of the outer periphery rubber part 3, which is the boundary between the inner periphery of the hollow rotating shaft and the outer periphery of the outer periphery rubber part 3, but since the two side surfaces 35, 37 of the outer periphery rubber part 3 have the above-mentioned tapered shape, cleaning liquid is less likely to remain in this area.

[0032] The shape, size, depth, etc. of the outer peripheral groove in the dynamic damper of the present invention may be such that, when the dynamic damper of the present invention is attached to the inner surface of a hollow rotating shaft and the outer peripheral rubber portion is compressed radially, the two portions 31, 33 separated in the direction of the central axis ω by the outer peripheral groove 3a on the outer peripheral surface of the outer peripheral rubber portion 3 move away from each other in the direction of the central axis ω, so that the outer peripheral surface sides 35a, 37a of the two side surfaces 35, 37 of the outer peripheral rubber portion 3 are positioned outside in the direction of the central axis ω relative to the inner peripheral surface sides 35b, 37b, and the two side surfaces 35, 37 of the outer peripheral rubber portion 3 have a tapered shape in which the inner diameter gradually decreases from the outer peripheral surface sides 35a, 37a toward the inner peripheral surface sides 35b, 37b. [Explanation of symbols]

[0033] 1. Dynamic Damper of the Present Invention 3 Outer rubber part 3a Outer groove 31, 33 Outer rubber part 35, 37 Side of outer rubber part 35a, 37a: Outer peripheral surface side of the side of the outer peripheral rubber portion 35b, 37b: Inner surface side of the outer rubber portion 5 Sleeve 7 Inner Weight 9 Mounting rubber 9a Connecting part 9b Slit 10 Hollow rotating shaft 10a Inner surface of hollow rotating shaft 101 Conventional Dynamic Damper 102 Outer periphery rubber part 103 Sleeve 104 Inner Weight 105 Mount rubber 105a Connection part 105b Slit ω center axis

[0034] This application claims priority to Japanese Patent Application No. 2020-194077, filed on November 24, 2020, the disclosure of which is incorporated herein in its entirety.

Claims

[Claim 1] A dynamic damper attached to an inner peripheral side of a hollow rotating shaft, a cylindrical outer circumferential rubber portion disposed on an outer diameter side and in close contact with an inner circumferential surface of the hollow rotating shaft; a cylindrical sleeve disposed on an inner peripheral side of the outer peripheral rubber portion; a cylindrical or columnar inner weight disposed at a position including a central axis of the hollow rotating shaft; a mount rubber provided between the sleeve and the inner weight and supporting the inner weight; having the outer circumferential rubber portion is cylindrical, and an outer circumferential groove is formed around the entire periphery at the center in the central axis direction of the outer circumferential surface of the outer circumferential rubber portion, a length of the sleeve in a direction parallel to the central axis coincides with a length of an inner peripheral surface of the outer peripheral rubber portion in a direction parallel to the central axis, and an outer peripheral surface of the sleeve and an inner peripheral surface of the outer peripheral rubber portion are entirely bonded to each other, When the outer rubber portion is attached to the inner surface of the hollow rotating shaft and compressed in the radial direction, two portions separated in the central axis direction by the outer groove on the outer surface of the outer rubber portion move in a direction away from each other in the central axis direction, so that the outer surface side of the two side surfaces of the outer rubber portion is positioned outward in the central axis direction than the inner surface side, and the two side surfaces of the outer rubber portion have a tapered shape in which the inner diameter gradually decreases from the outer surface side to the inner surface side (excluding those in which the center of gravity of the inner weight is offset to one side in the central axis direction of the sleeve with respect to the center of gravity of the sleeve, and the mounting rubber extends from the outer surface to the inner surface at an angle to one side in the central axis direction of the sleeve with respect to the radial direction of the sleeve).

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