JP2004092674A - Dynamic damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic damper in which a spring ratio of a high spring part and a low spring part of an elastic support member can be tuned in a wider range. <P>SOLUTION: On both of shaft end parts of a mass member 2 positioned between a pair of fixed members 1 and coaxially arranged outside a rotary shaft at a distance, a recessed end face 23 recessed inward in an axial direction and a convex end face 24 positioned outer than the recessed end face 23 in the axial direction are alternately provided in the circumferential direction. A pair of ring-shaped elastic support members 3 which are respectively connected with each shaft end part of the mass member 2 and each fixed member 1 and elastically support the both of the shaft end parts in the direction of shearing are constituted so that the high spring part 31 one end of which is connected to the convex end face 24, having a spring constant in the shearing direction set higher than an objective specific value and the low spring part 32 the one end of which is connected to the recessed end face 23, having the spring constant in the shearing direction set lower than the specific value are alternately arranged in the circumferential direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dynamic damper that is attached to a rotating shaft such as a drive shaft of an automobile and suppresses harmful vibration generated on the rotating shaft.
[0002]
[Prior art]
Conventionally, on a rotating shaft such as a drive shaft or a propeller shaft of an automobile, bending vibration and torsional vibration due to rotational imbalance caused by the rotation, etc. A dynamic damper is used. This dynamic damper achieves its function by converting its natural frequency to the predominant frequency of the harmful vibration to be excited, and converting and absorbing the vibration energy of the rotating shaft as the vibration energy of the dynamic damper by resonance. It is.
[0003]
As such a dynamic damper, a cylindrical metal mass member coaxially arranged at a distance outside the rotation shaft, and attached to the outer peripheral surface of the rotation shaft located outside both shaft ends of the mass member A pair of ring-shaped rubber fixing members, and a pair of ring-shaped rubber members respectively connected to each fixing member and each shaft end of the mass member to elastically support both shaft ends of the mass member in the shearing direction. What consists of an elastic support member is known. The natural frequency of the dynamic damper is basically determined by the mass of the mass member and the spring constant of the elastic support member in the shear direction.
[0004]
By the way, the above-described vibration damping effect of the dynamic damper is maximized when the resonance frequency (natural frequency) of the rotating shaft to which the dynamic damper is attached matches the resonance frequency (natural frequency) of the dynamic damper, When the respective resonance frequencies deviate beyond a certain small range, the values suddenly decrease.
[0005]
However, the resonance frequency of the rotating shaft varies due to variations in the shaft diameter and the shaft length, and the resonance frequency of the dynamic damper changes in characteristics due to variations in rubber hardness of the rubber elastic body and environmental changes such as temperature. Therefore, it is extremely difficult to adjust not only a state in which both resonance frequencies are completely coincident with each other, but also an adjustment within a range that can satisfy all of the fluctuations.
[0006]
Therefore, as shown in FIGS. 6 and 7, the applicant has set the high spring portions 31a, 31a in which the spring constant in the shearing direction is set higher than the target specific value, and set the spring constant lower than the specific value. There has been proposed a dynamic damper including a pair of elastic support members 3a, 3a in which low spring portions 32a, 32a are alternately arranged in the circumferential direction (Japanese Patent Application Laid-Open No. 9-89047). According to this dynamic damper, as shown in FIG. 8, a plurality of resonance frequencies are set over a wide range so as to straddle one resonance frequency which is a target of the rotation axis. The reduction of the vibration suppression effect caused by the variation in the distance can be minimized.
[0007]
[Problems to be solved by the invention]
By the way, in the case of the dynamic damper disclosed in the above publication, the spring constants of the high spring portions 31a, 31a and the low spring portions 32a, 32a of the elastic support members 3a, 3a are determined by the respective free shear lengths L3, L4. Therefore, the spring ratio of the high spring portions 31a, 31a and the low spring portions 32a, 32a can be tuned. However, if the spring ratio is to be further increased, the free spring length of the high spring portions 31a, 31a and the low spring portions 32a, 32a increases steadily, and the spring constant of the entire elastic support members 3a, 3a decreases accordingly. Resulting in. Therefore, even if the target spring ratio is obtained, the spring constant that becomes the target resonance frequency of the dynamic damper cannot be obtained.
[0008]
The present invention has been made in view of the above circumstances, and a problem to be solved is to provide a dynamic damper capable of tuning a spring ratio of a high spring portion and a low spring portion of an elastic support member in a wider range. It is assumed that.
[0009]
Means for Solving the Problems, Functions and Effects of the Invention
The invention according to claim 1, which solves the above-mentioned problem, comprises a pair of ring-shaped fixing members attached to the outer peripheral surface of the rotating shaft at a distance in the axial direction, and the rotating shaft positioned between the pair of fixing members. A cylindrical mass member coaxially arranged at a distance outside of the mass member, and connected to the respective shaft ends of the mass member and the respective fixing members so that both shaft ends of the mass member are sheared in the shear direction. A dynamic damper comprising a pair of ring-shaped elastic support members for elastically supporting the mass member, wherein both axial ends of the mass member have axially inwardly concave concave end surfaces and axially outwardly more than the concave end surfaces. Are provided alternately in the circumferential direction, and the elastic support member has a high spring portion in which one end is connected to the convex end surface and a spring constant in a shear direction is set to be higher than a target specific value. One end is connected to the concave end face in the shearing direction. Definitive spring constant is adopted a structure that has a lower spring portion is set lower than the specified value.
[0010]
Note that the target specific value here corresponds to the target resonance frequency of the rotating shaft, when setting the resonance frequency of the dynamic damper determined by the mass of the mass member and the spring constant of the rubber elastic member. The value of the spring constant.
[0011]
In the dynamic damper of the present invention, one end of the high spring portion of the elastic support member is connected to the convex end surface of the mass member, and one end of the low spring portion of the elastic support member is connected to the concave end surface of the mass member. The free shear length of the spring portion can be made sufficiently longer than the free shear length of the high spring portion, and the free shear length of the high spring portion can be made shorter. Thus, the spring ratio of the high spring portion and the low spring portion can be tuned without lowering the spring constant of the entire elastic support member, and the tuning range of the spring ratio is expanded. In addition, the tuning range of the spring constant (target specific value) of the entire elastic support member at the target resonance frequency of the dynamic damper is expanded.
[0012]
Therefore, according to the dynamic damper of the present invention, the spring ratio of the high spring portion and the low spring portion of the elastic support member can be tuned in a wider range.
[0013]
The invention according to claim 2 adopts a configuration in which the concave end face and the convex end face of the mass member according to the invention according to claim 1 are arranged at axially symmetric positions.
[0014]
According to this means, since the high spring portion and the low spring portion of the elastic support member are arranged in a well-balanced manner in the circumferential direction, tuning of their spring ratio becomes easy, and a better vibration suppressing effect can be obtained. It becomes.
[0015]
According to a third aspect of the present invention, the mass member according to the first or second aspect is formed by winding a metal plate formed into a predetermined shape by press molding into a cylindrical shape, and joining opposing opposite ends. Is adopted.
[0016]
According to this means, the mass member having the concave portion and the convex portion at both shaft end portions can be easily manufactured while suppressing an increase in cost.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a cross-sectional view of the dynamic damper according to the present embodiment along the axial direction, which is a cross-sectional view taken along line II of FIG. 2, and FIG. 2 is a front view of the dynamic damper viewed from the axial direction. .
[0019]
As shown in FIGS. 1 and 2, the dynamic damper according to the present embodiment has a pair of ring-shaped fixing members 1 and 1 attached to the outer peripheral surface of a rotating shaft, and is formed in a cylindrical shape and has two shaft ends. The mass member 2 in which the concave end surfaces 23 and 23 and the convex end surfaces 24 and 24 are alternately provided in the circumferential direction is connected to each shaft end of the mass member 2 and each of the fixing members 1 and 1, respectively. , 31 and a pair of ring-shaped elastic support members 3, 3 alternately provided in the circumferential direction with low spring portions 32, 32.
[0020]
The fixing members 1 and 1 are formed in a ring shape from a rubber material such as natural rubber. A pair of the fixing members 1 and 1 is used, and is fitted to an outer peripheral surface of a rotating shaft such as a drive shaft and is attached at a distance in the axial direction. The fixing members 1 and 1 have an inner diameter slightly smaller than the outer diameter of the rotary shaft, and are attached to the outer peripheral surface of the rotary shaft when attached to the rotary shaft. A ring-shaped locking groove 11 to which a fixing band (not shown) is attached is formed on the outer peripheral surface of one fixing member 1.
[0021]
The mass member 2 includes a mass body 21 formed of a ferrous metal in a cylindrical shape, and a covering rubber 22 that covers the inner and outer peripheral surfaces of the mass body 21. The mass member 2 has an inner diameter that is larger than the outer diameter of the rotating shaft by a predetermined dimension, is located between the pair of fixed members 1, 1, and is coaxially arranged outside the rotating shaft at a distance. . Thus, the mass member 2 can be displaced relative to the rotating shaft in the radial direction. The two axial end portions of the mass member 2 are provided with two concave end surfaces 23, 23 recessed inward in the axial direction, and two convex end surfaces 24, 24 located outside the concave end surfaces 23, 23 in the axial direction. Are provided alternately in the circumferential direction. These concave end surfaces 23, 23 and convex end surfaces 24, 24 are arranged at axially symmetric positions, respectively.
[0022]
The mass body 21 used here is formed by winding a metal plate formed into a predetermined shape by press molding into a cylindrical shape, and joining opposite ends. That is, first, a metal plate material is press-formed to form a rectangular metal plate 21a as shown in FIG. At both ends on the long side of the metal plate 21a, concave end surfaces 23 that are concave inward and convex end surfaces 24 that are located axially outward from the concave end surface 23 are provided alternately. Further, a plurality of through-holes 25,... Penetrating in the thickness direction are provided in the central portion in the width direction of the metal plate 21a along the longitudinal direction.
[0023]
Next, the metal plate 21a is wound into a cylindrical shape so that both short-side end surfaces of the metal plate 21a face each other, and the opposite ends are joined together. At this time, the joint may be firmly joined using welding or the like. Thereby, the mass body 21 as shown in FIGS. 4 and 5 is formed. In addition, the coating rubber 22 is formed on the inner peripheral surface and the outer peripheral surface of the mass body 21 thus manufactured by integrally vulcanizing and molding a rubber material such as natural rubber with the mass body 21.
[0024]
As shown in FIGS. 1 and 2, the elastic support members 3, 3 are formed of a rubber material such as natural rubber in a substantially frustoconical ring shape, and the small diameter side thereof is connected to one of the fixed members 1. The large diameter side is connected to one shaft end of the mass member 2. The elastic support members 3, 3 are formed by integral vulcanization molding with the mass body 21, and at the time of the vulcanization molding, the pair of fixing members 1, 1 and the covering rubber 22 are also formed with the elastic support members 3, 3, respectively. They are formed simultaneously in a state of being integrally connected.
[0025]
The elastic support members 3, 3 have one ends connected to the convex end surfaces 24, 24 of the mass member 2 so that the spring constant in the shearing direction has a target specific value (the elastic support member 3 having a target resonance frequency of the dynamic damper). 3), and one end is connected to the concave end surfaces 23, 23 of the mass member 2 so that the spring constant in the shearing direction is lower than the specific value. It has two low spring portions 32, 32 set. These high spring portions 31, 31 and low spring portions 32, 32 are alternately arranged in the circumferential direction.
[0026]
One end of each of the high spring portions 31, 31 is connected to the convex end surfaces 24, 24 of the mass member 2 and the free shear length L1 thereof is shortened, so that the predetermined spring constant is set higher than the specific value. I have. In addition, the low spring portions 32, 32 are set to a predetermined spring constant lower than the specific value, because one end is connected to the concave end surfaces 23, 23 of the mass member 2 and the free shear length L2 is lengthened. Have been.
[0027]
The dynamic damper of the present embodiment configured as described above is used as follows. First, when the dynamic damper is mounted on the drive shaft of an automobile, before the drive shaft is mounted on the vehicle body, the inner holes of the fixing members 1 and 1 are expanded and the dynamic damper is inserted from the shaft end of the drive shaft. A dynamic damper is arranged at a predetermined position. Then, the fixing of the dynamic damper to the drive shaft is completed by mounting the fixing band in the locking groove 11 of the fixing member 1.
[0028]
Then, when harmful vibrations are excited with the rotation of the drive shaft, the mass member 2 of the dynamic damper whose natural frequency is adapted to the frequency of the harmful vibrations is caused by the shear deformation of the elastic support members 3. By resonating, the vibration energy of the drive shaft is absorbed, and the excited harmful vibration is suppressed. In this case, the resonance frequency of the dynamic damper is set over a wide range so as to have a plurality of resonance frequencies so as to straddle one resonance frequency targeted by the drive shaft. Even if there is some variation, there is little possibility that the resonance frequency of the drive shaft and the resonance frequency of the dynamic damper are largely shifted due to variation or the like. Therefore, the resonance frequency of the drive shaft coincides with the resonance frequency of the dynamic damper, and a state where the maximum vibration suppression effect of the dynamic damper can be exhibited is secured.
[0029]
As described above, in the dynamic damper of the present embodiment, a plurality of resonance frequencies are set in a wide range so as to straddle one resonance frequency that is a target of the rotation axis. The reduction of the vibration suppression effect caused by the variation can be minimized.
[0030]
In the dynamic damper of the present embodiment, one ends of the high spring portions 31, 31 of the elastic support members 3, 3 are connected to the convex end surfaces 24, 24 of the mass member 2, and the low spring portions 32 of the elastic support members 3, 3 are connected. , 32 is connected to the concave end surfaces 23, 23 of the mass member 2, so that the free shear length L2 of the low spring portions 32, 32 is sufficiently longer than the free shear length L1 of the high spring portions 31, 31. It is also possible to shorten the free shear length L1 of the high spring portions 31, 31. Thereby, the spring ratio of the high spring portions 31, 31 and the low spring portions 32, 32 can be tuned without lowering the spring constant of the entire elastic support members 3, 3, and the tuning range of the spring ratio is expanded. Is done. In addition, the tuning range of the spring constant (target specific value) of the entire elastic support members 3 and 3 at the target resonance frequency of the dynamic damper is expanded. Therefore, according to the dynamic damper of the present embodiment, the spring ratio of the high spring portions 31, 31 and the low spring portions 32, 32 of the elastic support members 3, 3 can be tuned in a wider range.
[0031]
In addition, since the concave end surfaces 23, 23 and the convex end surfaces 24, 24 of the mass member 2 in the present embodiment are arranged at axially symmetric positions, respectively, the high spring portions 31, 31 of the elastic support members 3, 3 are low. Since the spring portions 32 and 32 are arranged in a well-balanced manner in the circumferential direction, tuning of their spring ratios is facilitated, and a better vibration suppression effect can be obtained.
[0032]
Further, since the mass body 21 of the mass member 2 in the present embodiment is formed by winding a metal plate 21a formed into a predetermined shape by press molding into a tubular shape and joining opposite ends thereof, both of them are formed. The mass body 21 having the concave portions 23, 23 and the convex portions 24, 24 at the shaft end can be easily manufactured while suppressing an increase in cost. The mass body 21 can also be manufactured by another method conventionally used, such as forging.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view along an axial direction of a dynamic damper according to an embodiment of the present invention, which is a cross-sectional view taken along line II of FIG. 2;
FIG. 2 is a front view of the dynamic damper according to the embodiment of the present invention as viewed from an axial direction.
FIG. 3 is a development view of a mass member according to the embodiment of the present invention.
FIG. 4 is a front view of the mass member according to the embodiment of the present invention as viewed from the axial direction.
FIG. 5 is a side view of the mass member according to the embodiment of the present invention as viewed in the direction of arrow a in FIG.
6 is a cross-sectional view along the axial direction of the conventional dynamic damper, and is a cross-sectional view taken along line VI-VI in FIG. 7;
FIG. 7 is a front view of a conventional dynamic damper viewed from an axial direction.
FIG. 8 is a graph showing a relationship between an acceleration level and a frequency of a mass member of a conventional dynamic damper.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixed member 2 ... Mass member 3, 3a ... Elastic support member 11 ... Locking groove 21 ... Mass body 21a ... Metal plate 22 ... Rubber coating part 23 ... Concave end surface 24 ... Convex end surface 25 ... Through-hole 31, 31a ... High Spring portions 32, 32a: low spring portions L1, L2, L3, L4: free to shear

Claims (3)

A pair of ring-shaped fixing members attached to the outer peripheral surface of the rotating shaft at a distance in the axial direction, and coaxially disposed at a distance outside the rotating shaft between the pair of fixing members; A cylindrical mass member, and a pair of ring-shaped elastic support members connected to each shaft end of the mass member and each of the fixing members to elastically support both shaft ends of the mass member in a shearing direction; In a dynamic damper with
At both axial ends of the mass member, a concave end surface recessed inward in the axial direction and a convex end surface located axially outward from the concave end surface are provided alternately in the circumferential direction, and the elastic support member is A high spring portion, one end of which is connected to the convex end surface and the spring constant in the shear direction is set higher than a target specific value, and the spring constant in the shear direction where one end is connected to the concave end surface is higher than the specific value. And a low spring portion set low. 2. The dynamic damper according to claim 1, wherein the concave end surface and the convex end surface of the mass member are arranged at axially symmetric positions, respectively. 3. 3. The dynamic damper according to claim 1, wherein the mass member is formed by winding a metal plate formed into a predetermined shape by press molding in a cylindrical shape, and joining opposite ends thereof. 4.

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