JPH0694075A - Dynamic damper of rotator - Google Patents

Abstract

PURPOSE:To provide a dynamic damper capable of controlling a vibrational amplification by means of a resonant phenomenon of a rotator in a wide frequency area. CONSTITUTION:A dynamic damper 6 is composed of an elastic body 17 and an inertia body 18 annularly installed. In this case, the inertial body 18 is plurally divided in the circumferential direction, while an axial sectional form of the elastic body 17 is formed into a trapezoid where the axial direction varies along the radial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimic damper mounted on a rotating body such as a drive shaft of an automobile, and more particularly, to an improved elastic body structure capable of obtaining a damping effect in a wide frequency range. Regarding

[0002]

2. Description of the Related Art Generally, a rotating body has a vibration amplification phenomenon due to a resonance phenomenon, and its resonance frequency f is determined by the mass (m) and the spring constant (k) of the rotating body, and the following equation (A ) Is required. f = 1 / 2π × (k / m) ^0.5 (A) Therefore, in the above drive shaft, for example, FIG.
The vibration indicated by the curve a is generated at 6.

Therefore, a rotating body such as a drive shaft of an automobile may be equipped with a dynamic damper in order to reduce vibration amplification due to a resonance phenomenon. As such a dynamic damper, conventionally, for example, FIGS.
There is one shown in 3. This has a structure in which a cylindrical boss portion 2 is attached to a drive shaft 1 with a pin 3, an elastic body 4 is fixed to the boss portion 2, and an inertial body 5 is fixed around the elastic body 4. The elastic body 4 has a rectangular cross section in the axial direction as shown in FIG. 14, and its spring constant is equivalently similar to that of the spring shown in FIG. 15, and is substantially constant even when compressed. The inertial body 5 is composed of a ring-shaped simple substance.

A vibration damping device as shown in Japanese Utility Model Laid-Open No. 59-3041 has also been proposed. This damping device
A boss portion fitted on the drive shaft, a ring-shaped weight arranged concentrically with the boss portion via an elastic coupling member, and a space between the adjacent elastic coupling members in the boss portion direction. It is composed of a stopper that projects and restricts the amount of expansion and contraction of the elastic coupling member, and a closing member that connects the space between the stopper and the boss portion with a thin elastic member.

In the conventional device shown in FIGS. 12 and 13 or the above publication, the vibration reducing effect shown in FIG. 16 is obtained.
In the figure, the curve a is the curve b when the damper is not provided.
Is a vibration characteristic when the damper is provided. As is clear from the figure, the vibration level is attenuated when the frequency is f0, and the vibration reduction effect is recognized in the hatched portion A surrounded by the curves a and b centering on f0.

[0006]

However, in the case of the above-mentioned conventional apparatus, although the effect is recognized in the vicinity of the frequency f0, in the hatched portion B surrounded by the curves a and b near the frequencies f1 and f2, on the contrary, the vibration level is As a result, the vibration is increased due to the rise of the damper.
This is the mass of the inertial body in the dynamic damper (m)
This is because the resonance point obtained from the above equation A is invariant from the spring constant (k) of the elastic body, and antiresonance points f1 and f2 exist.

The present invention has been made in view of the above-mentioned conventional problems, and it is possible to suppress the deterioration portion due to the anti-resonance point as described above and suppress the vibration amplification due to the resonance phenomenon of the rotating body in a wide frequency range. The purpose is to provide a damper.

[0008]

According to a first aspect of the present invention, there is provided a dimic damper having an elastic body and an inertial body around a rotating body, wherein the elastic body and the inertial body are provided around the rotating body. It is concentrically and annularly provided, the inertial body is divided into a plurality of pieces in the circumferential direction, and the cross-sectional shape of the elastic body in the axial direction has a modified shape in which the axial dimension changes in the radial direction. I am trying.

According to a second aspect of the present invention, in a dimic damper having an elastic body and an inertial body around a rotating body, the elastic body and the inertial body are concentric with each other around the rotating body, and It is characterized in that it is provided in an annular shape, the inertial body is divided into a plurality in the circumferential direction, and a portion having a small spring constant is provided in the elastic body. Here, the portion having a small spring constant includes a space.

[0010]

According to the diamic damper for a rotating body of the present invention, the inertia body is divided into a plurality of pieces in the circumferential direction and the elastic body has a different cross-sectional shape. Therefore, the rotating body and the dynamic damper rotate. Then, the inertial body is displaced outward by the centrifugal force to change the cross-sectional shape of the elastic body, which causes the spring constant of the elastic body to change, for example, as shown by characteristic curves B and C in FIG. As a result, as can be seen from the above formula A, the resonance point changes with the frequency (the rotation speed of the drive shaft), and by appropriately setting the above-mentioned variant, vibration deterioration due to anti-resonance is suppressed and a damping effect in a wide frequency range is obtained. Will be done.

Further, according to the second aspect of the invention, since the inertial body is divided into a plurality of pieces in the circumferential direction and the elastic body is provided with a portion having a small spring constant, the displacement of the inertial body causes a change in the spring constant of the elastic body. When the small portion is deformed to the limit, the spring constant of the entire elastic body changes stepwise as shown by the characteristic line (a) in FIG. As a result, the resonance point changes with the frequency in two steps, for example, and the vibration amplification can be reduced in a wider frequency range.

As described above, according to the present invention, since the spring constant is changed according to the rotational speed of the drive shaft, it is possible to obtain a damper in which the vibration level does not deteriorate due to anti-resonance.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 7 are views for explaining a dynamic damper of a drive shaft according to a first embodiment of the present invention. FIG. 1 is an arrangement view showing a mounting state of a dynamic damper of this embodiment, FIGS. 2 and 3 are axial sectional views and front views of the dynamic damper, FIG. 4 is an axial sectional view of an elastic body, and FIG. It is a side view of a spring equivalent to the elastic body of FIG.

In FIG. 1, reference numeral 7 denotes a front wheel drive system, which drives the power of an engine 8 from a transmission 9 via left and right drive shafts 10 and 11 to left and right front wheels 12 and 13.
It is structured to transmit to. The dynamic damper 6 of this embodiment is attached to the left drive shaft 10.

In the dynamic damper 6, as shown in FIGS. 2 and 3, the boss portion 15a of the dish-shaped casing 15 is attached to the drive shaft 14 with the pin 16, and the elastic body 17 is fixed to the inner surface of the peripheral wall 15b of the casing 15. However, the inertial body 18 is fixed to the inner surface of the elastic body 17. The inertial body 18 is an arcuate body formed by dividing an annular body into three in the circumferential direction as shown in FIG. Further, the elastic body 17 is a rubber annular body, and its axial cross-sectional shape is, as shown in FIG. 4, a deformed shape in which the axial dimension X becomes smaller toward the axial center along the radial direction, that is, a trapezoidal shape. Has become.

Since the elastic body 17 has a trapezoidal cross section, its spring constant is equivalent to that of a spring having the shape shown in FIG. 5, for example. That is, the spring constant increases as the radial compression amount increases.

Next, the function and effect of this embodiment will be described. When the drive shaft 14 rotates, the elastic body 17 and the inertial body 18 also rotate accordingly, and a centrifugal force corresponding to the rotation speed acts outwardly on the inertial body 18.
In this case, since the inertial body 18 is divided in the circumferential direction, it is moved outward by the centrifugal force, and thereby the elastic body 17 is compressed and deformed into the shape shown by the broken line in FIG.

The rotational speed of the drive shaft 10 is r1.
The trapezoidal elastic body 17 is transformed into a shape shown by a broken line in FIG. Along with this, the spring constant changes from k1 to k5, as shown by the characteristic line B in FIG. Note that such a change in the spring constant is similar to the change in the spring constant when the spring having the shape shown in FIG. 5 is compressed. Therefore, as can be seen from the above formula A, the resonance frequency changes to f1 to f5 along with the frequency (the rotation speed of the drive shaft).

FIG. 6 is a diagram for explaining the damping effect. In the figure, 6a is the vibration characteristic of the drive shaft itself, and characteristic lines 6b to 6d show the damping characteristics when the rotational speeds of the drive shaft are r2, r3, and r4, respectively. For example, at a rotation speed r2, the spring constant is k2, and therefore the resonance frequency is f2. As a result, the damping effect as shown by the curve 6b is obtained, the resonance frequency becomes f3 at the rotational speed r3 and the damping effect shown by the curve 6c is obtained, and the resonant frequency becomes f4 at the rotational speed r4 as shown by the curve 6d. A damping effect is obtained. In this way, the resonance frequency is f2
As a result of changing to f4, the damping characteristic as a whole becomes the vibration level shown by the curve 7 in FIG.

Here, the change characteristic of the spring constant shown by the characteristic line B in FIG. 11 is, for example, a characteristic when the sectional shape of the elastic body 17 in the axial direction approaches the rectangular shape shown in FIG. 14 from the above trapezoidal shape. The characteristic indicated by the characteristic line 2 is reached through the change characteristic indicated by the line C. In this way, by changing the cross-sectional shape of the elastic body, it is possible to change the changing characteristic of the spring constant with respect to the rotational speed, so that it is possible to make a fine adjustment to the resonance frequency.

FIG. 8 and FIG. 9 show a second aspect of the invention of claim 2.
FIG. 9 is a diagram for explaining the embodiment, FIG. 8 is a sectional view in the direction perpendicular to the axis, and FIG. 9 is a sectional view taken along line VIII-VIII of FIG. 8.

In the figure, 19 is an inertia body divided into three in the circumferential direction, and 20 is an annular elastic body.
9 is fixed to the inner surface of the elastic body 20. Although not shown, the elastic body 20 is fixed to the inner surface of the casing similar to that of the first embodiment. The elastic body 2
Inside 0, a space 21 is provided as a portion having a small spring constant. The elastic body 20 in this embodiment has a rectangular cross section in the axial direction as shown in FIG. 9, and the outer and inner elastic portions 20a and 20b are formed by the space 21.
It has a separate shape.

Next, the function and effect of this embodiment will be described. When the drive shaft 22 rotates, the inertial body 1
A centrifugal force according to the number of rotations acts on 9 outwardly, the elastic body 20 is pressed outward by this centrifugal force, and the inner elastic portion 20b is deformed outward in particular. The space 21 is pressed and narrowed as the inner elastic portion 20b is deformed, and when the drive shaft 22 reaches a certain rotational speed r0, the inner elastic portion 20b comes into contact with the outer elastic portion 20a. The change in the spring constant at this time is shown by the characteristic line (a) in FIG. That is, when the rotational speed exceeds r0, the spring constant changes stepwise from k0 to k0 '. This is the outer and inner elastic portions 20.
This is because a and 20b are brought into contact with each other to be integrated, and the spring constant in this integrated state is changed.

As described above, in this embodiment, since the space 21 is provided inside the elastic body 20, the spring constant can be changed stepwise, and the damping effect can be obtained at two resonance frequencies.

Although the space 21 is provided as a portion having a small spring constant in the above embodiment, the portion having a small spring constant in the present invention may be realized by changing the constituent material. Also in this case, the spring constant can be changed stepwise according to the rotation speed of the drive shaft 22.

FIG. 10 shows the third aspect of the invention according to claims 1 and 2.
An example is shown. In this embodiment, an annular elastic body 23 is fixed around the drive shaft 25, and an inertial body 24 divided into three in the circumferential direction is attached to the outer circumference of the elastic body 23. In the case of the present embodiment, centrifugal force due to rotation acts on the inertial body 24, and the elastic body 23 is deformed by pulling the elastic body 23 outward.

The scope of application of the present invention is not limited to the dynamic damper for a drive shaft of an automobile in the above-mentioned embodiment, and any point is required as long as it is necessary to suppress the vibration due to the resonance phenomenon of the rotating body. Applicable.

[0028]

As described above, according to the dynamic damper of the rotating body of the present invention, the inertial body is divided into a plurality of pieces in the circumferential direction, and the elastic body is deformed or the elastic body has a small spring constant. Since, the spring constant can be changed according to the rotation speed of the drive shaft,
This has the effect of reducing vibration amplification in a wide frequency range.

[Brief description of drawings]

FIG. 1 is a front view showing a mounted state of a dynamic damper of a drive shaft according to a first embodiment of the present invention.

FIG. 2 is a sectional side view of the first embodiment.

FIG. 3 is a sectional front view of the first embodiment.

FIG. 4 is an enlarged sectional view in the axial direction of the elastic body of the first embodiment.

FIG. 5 is a schematic side view of a spring equivalent to the elastic body of the first embodiment.

FIG. 6 is a characteristic diagram showing a vibration reduction effect of the first embodiment.

FIG. 7 is a characteristic diagram showing a vibration reduction effect of the first embodiment.

FIG. 8 is a sectional front view of a dynamic damper of a drive shaft according to a second embodiment of the present invention.

9 is an enlarged cross-sectional view taken along line VIII-VIII of FIG.

FIG. 10 is a front sectional view of a dynamic damper of a drive shaft according to a third embodiment of the present invention.

FIG. 11 is a characteristic diagram showing changes in spring constant of the elastic body with respect to displacement of the inertial body in the first to third examples.

FIG. 12 is a cross-sectional side view in the axial direction of a conventional dynamic damper.

13 is a sectional front view of the dynamic damper of FIG.

FIG. 14 is an enlarged cross-sectional view in the axial direction of the conventional elastic body.

FIG. 15 is a schematic side view of a spring equivalent to the elastic body of the conventional example.

FIG. 16 is a characteristic diagram showing a vibration reduction effect when a conventional damper is used.

[Explanation of symbols]

 6 Dimic damper 10,22,25 Drive shaft (rotating body) 17,20,23 Elastic body 18,19,24 Inertial body

Claims (2)

[Claims] 1. A dimic damper having an elastic body and an inertial body around a rotating body, wherein the elastic body and the inertial body are provided concentrically and annularly around the rotating body, A dimming damper for a rotating body, characterized in that the inertial body is divided into a plurality of pieces in the circumferential direction, and the elastic body has a cross-sectional shape in the axial direction which is a shape whose axial dimension changes in the radial direction. 2. A dimic damper comprising an elastic body and an inertial body around a rotating body, wherein the elastic body and the inertial body are concentrically and annularly provided around the rotating body, A dynamic damper for a rotating body, characterized in that the inertial body is divided into a plurality of pieces in the circumferential direction, and a portion having a small spring constant is provided in the elastic body.