JPH08210441A - Dynamic damper - Google Patents

Abstract

PURPOSE: To provide a dynamic damper whereby a natural frequency in an axial orthogonal direction and in an axial line direction can be reduced while ensuring strength and durability. CONSTITUTION: A device comprises a fixed member 11 mounted in a rotary shaft S, mass member 12 arranged so as to surround the rotary shaft with a prescribed space apart and an elastic member 13 of connecting these fixed member and mass member, and by providing a pair of the mass member and the elastic member with a space apart in an axial line direction of the rotary shaft, two system vibrating systems 14, 15 are formed in the fixed member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic damper mounted on a rotary shaft such as a drive shaft or a propeller shaft of a vehicle so as to suppress vibrations generated on these rotary shafts.

[0002]

2. Description of the Related Art Generally, it is known that vibrations due to unbalanced mass, vibrations such as bending vibrations and torsional vibrations are generated on a rotating shaft such as a drive shaft or a propeller shaft of a vehicle. Has been.

Especially, in a front-wheel drive vehicle, since the drive shaft is connected to the front wheels to which the steering mechanism is connected, the vibration generated in the drive shaft is transmitted to the driver via the steering mechanism. Easy to be transmitted to.

In order to solve such a problem, in the conventional example, a dynamic damper is attached to the rotary shaft,
The vibration is suppressed by absorbing the vibration energy generated in the rotating shaft.

FIG. 4 shows a conventional dynamic damper. The dynamic damper 1 includes a fixed member 2 fitted on the rotating shaft S and a mass member 3 arranged so as to surround the fixed member 2. And an elastic member 4 that connects the fixing member 2 and the mass member 3 to each other, and the elastic member 4 is arranged along a direction orthogonal to the axis of the rotation axis S.

Such a dynamic damper 1 resonates with respect to vibration in a direction orthogonal to the axis of the rotary shaft S,
The rotating shaft S and the mass member 3 are moved relative to each other in the direction orthogonal to the axis, and the elastic member 4 is elastically deformed in the compression / pulling direction.
It absorbs the vibration energy in the direction orthogonal to the axis and attenuates the vibration.

Further, due to the resonance of the rotating shaft S in the axial direction, the rotating shaft S and the mass member 3 are relatively moved in the axial direction, and the elastic member 4 is elastically deformed in the shearing direction. The elastic deformation absorbs the vibration energy of the rotating shaft S in the axial direction and attenuates the vibration.

In order to resonate the rotary shaft S and the dynamic damper 1 described above, it is necessary to match the natural frequency of the dynamic damper 1 with the frequency that is the target of vibration suppression of the rotary shaft S. The natural frequency of the dynamic damper 1 is adjusted by adjusting the mass of the mass member 3 and adjusting the spring constant by changing the shape of the elastic member 4.

[0009]

By the way, when the dynamic damper 1 is applied to a vehicle or the like, it is desired to reduce the natural frequencies of the dynamic damper 1 in the axial direction and the axis-perpendicular direction.

Since the natural frequency in the axial direction described above is set based on the shear deformation of the elastic member 4 as described above, its spring constant is small and the natural frequency can be relatively easily reduced. However, since the natural frequency in the direction orthogonal to the axis is set based on the compression / tensile deformation of the elastic member 4, in order to reduce the natural frequency in the direction orthogonal to the axis, It is necessary to make a large shape change such as reducing the axial length or increasing the axial orthogonal length.

However, if the length of the elastic member 4 in the axial direction is reduced, there is a problem that the strength of the elastic member 4 is reduced. If the length of the elastic member 4 in the direction orthogonal to the axis is increased, the dynamic damper is increased. Therefore, there arises a problem that the occupied volume of No. 1 becomes large and the installation space is expanded.

On the other hand, the deformation mode of the elastic member 4 at the time of vibration in the axial direction is shearing as described above, and when the amplitude increases, the spring constant hardly changes and the natural frequency hardly changes.

Therefore, the resonance state is maintained even when an excessive amplitude is generated in the axial direction, and as a result, the above-mentioned excessive amplitude cannot be attenuated and the elastic member 4 exceeds the fatigue limit. It is easy to cause deterioration of durability.

Further, in the above-mentioned dynamic damper 1, once the specifications of the mass member 3 and the elastic member 4 are set, the natural frequency is uniquely determined by the set specifications, which is applicable. The versatility is narrow due to the limited rotation axis.

The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide a dynamic damper capable of reducing the natural frequency in the axis orthogonal direction and the axis direction while ensuring strength and durability. The first purpose.

A second object of the present invention is to provide a dynamic damper capable of suppressing an excessive amplitude in the axis orthogonal direction or the axis direction.

A third object of the present invention is to provide a dynamic damper applicable to a plurality of rotating shafts having different natural frequencies.

[0018]

In order to achieve the first object, a dynamic damper according to a first aspect of the present invention has a fixed member attached to a rotary shaft and a predetermined distance between the rotary shaft. A mass member disposed so as to surround the elastic member and an elastic member connecting the fixing member and the mass member, and the mass member and the elastic member are provided as a pair at intervals in the axial direction of the rotation shaft. Thus, two vibration systems are formed in the fixing member.

According to a second aspect of the present invention, in order to achieve the first and second objects, each of the elastic members in the first aspect has an end portion of the fixing member. A first deformable portion extending from the end of the first deformable portion in a direction orthogonal to the axis of the rotary shaft and connected to an inner surface of the mass member. It is characterized by being constituted by.

Further, in order to achieve the second object and the third object, the dynamic damper according to a third aspect of the present invention has one vibration system and the other vibration system according to the first or second aspect. The system is characterized by having different natural frequencies.

[0021]

According to the dynamic damper of the first aspect of the present invention, since the mass members are distributed and arranged in the two vibration systems, one elastic member can be used without reducing the mass of the mass member as a whole. The mass of the mass member supported by the member is reduced, and along with this, it is possible to reduce the thickness of each elastic member, and it is possible to set a low natural frequency while ensuring the strength of the elastic member.

Further, according to the dynamic damper of the second aspect of the present invention, the spring constant based on the shear deformation in the first deforming portion of the elastic member provided along the axial direction, and the mass of the mass member. The natural frequency of the rotary shaft in the direction perpendicular to the axis is set by the spring constant based on the shear deformation of the second deformable portion provided along the direction orthogonal to the shaft, and the mass of the mass member. The natural frequency in the axial direction is set.

Therefore, since both the natural frequency in the direction orthogonal to the axis and the natural frequency in the axial direction of this dynamic damper are set by the spring constant based on the shear deformation of the elastic member, the respective spring constants are suppressed to be small. As a result, the natural frequency in both directions is suppressed to be low in a state where the shape of the elastic member sufficient to support the mass member is secured.

On the other hand, when an excessive amplitude occurs in the direction orthogonal to the axis, the mass member is allowed to move due to shear deformation in the first deforming portion in the axial direction at the initial stage of deformation of the elastic member, but the amplitude is predetermined. When the value becomes equal to or more than the value, the second deformable portion is brought into contact with the rotary shaft to be compressed / pulled and deformed.

As a result, the spring constant that determines the natural frequency of the dynamic damper in the direction orthogonal to the axis is compressed.
The spring constant changes to a large spring constant due to tensile deformation, and the natural frequency of the dynamic damper increases accordingly, resonance is blocked, and excessive amplitude in the direction orthogonal to the axis is suppressed.

Further, according to the dynamic damper of the third aspect of the present invention, when one vibration system is in a resonance state, the other vibration system is non-resonant because the resonance points of the respective vibration systems are different. The vibration is stopped.

When an excessive amplitude in the axial direction occurs in the vibrating system in the resonance state, the mass member constituting this vibrating system contacts the mass member constituting the other vibrating system, The vibration energy in one vibration system is absorbed by the elastic member of the other vibration system, and thereby the excessive amplitude in the axial direction of the vibration system in the resonance state is suppressed.

Further, since the natural frequencies of the two vibration systems are different, it is possible to selectively use the rotary shafts having different natural frequencies.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 10 indicates a dynamic damper according to the present embodiment.
Reference numeral 0 denotes a fixing member 11 attached to the rotating shaft S, a mass member 12 arranged so as to surround the rotating shaft S at a predetermined interval, and these fixing members 11 and 12
And an elastic member 13 for connecting the
And a pair of elastic members 13 are provided at intervals in the axial direction of the rotating shaft S, so that two ends of the fixing member are provided.
It has a schematic configuration in which vibration systems 14 and 15 of the system are formed.

Next, these details will be described.
The one vibration system 14 and the other vibration system 15 have the same configuration except that the directions thereof are opposite to each other. Therefore, in the following description, the one vibration system 14 will be described.
Will be described.

The fixing member 11 is made of, for example, an elastic material such as natural rubber in a cylindrical shape, and has an inner diameter smaller than the outer diameter of the rotating shaft S so that the outer circumference of the rotating shaft S is small. By being fitted in the press-fitted state, the rotary shaft S is fixed at a predetermined position.

Further, an annular groove 11a having a predetermined depth is formed on the outer peripheral surface of the fixing member 11 over the entire circumference, and for example, the fixing member 11 and the rotary shaft S are firmly fixed to each other. A metal band or the like for wearing is attached.

The mass member 12 is formed, for example, by cutting a metal pipe such as a steel pipe having a predetermined wall thickness to a predetermined length, and the surface thereof is covered with a coating layer 16 made of natural rubber or the like. It is covered and shielded from the outside air.

As the mass member 12, other metals or materials other than metals can be used as long as a predetermined mass can be obtained.

The elastic member 13 is made of, for example, an elastic material such as natural rubber like the fixing member 11, and has an inner diameter larger than the outer diameter of the rotating shaft S in this embodiment. Further, as shown in FIG. 1, a cylindrical first deformable portion 13a having a predetermined length L is provided, and one end of this first deformable portion 13a is connected to one end of the fixing member 11 in the axial direction. The rotation axis S
A predetermined space is provided between the and, and they are held coaxially.

At the other end of the first deformable portion 13a, a second deformable portion 13b extending a distance M in a direction orthogonal to the axis of the rotary shaft S is integrally formed over the entire circumference. The second deformable portion 13b is continuously provided, and the tip portion of the second deformable portion 13b is the coating layer 1
When the mass member 12 is connected to the inner surface of the rotary shaft S through the elastic member 13 and the fixed member 11,
It is fixed to and is held coaxially with the rotation axis S.

Each of the vibration systems 14 and 15 having such a configuration is formed so as to be line-symmetrical with respect to a line orthogonal to the rotation axis S in the longitudinal sectional shape.

In the dynamic damper 10 of this embodiment having the above-described structure, when vibration occurs on the rotary shaft S, the resonance between the rotary shaft S and the respective vibration systems 14 and 15 of the dynamic damper 10 is generated as in the conventional case. Thereby, the elastic member 13 of each of the vibration systems 14 and 15 is elastically deformed, the vibration energy of the rotating shaft S is absorbed, and the vibration of the rotating shaft S is suppressed.

Then, the dynamic damper 1 of this embodiment
0 has a configuration in which the mass member 12 is divided into two vibration systems 14 and 15 and is supported by different elastic members 13, so that the mass supporting load of each elastic member 13 is reduced. Thus, the thickness of each elastic member 13 can be reduced without lowering the strength.

Therefore, the spring constant of the elastic member 13 can be reduced, and the natural frequency of the dynamic damper 10 can be suppressed to a small value.

Further, in this embodiment, the elastic member 13
Is constituted by the first deformable portion 13a extending in the axial direction and the second deformable portion 13b extending in the axis orthogonal direction, and therefore, due to shear deformation of the first deformable portion 13a against vibration in the axis orthogonal direction, With respect to the vibration in the axial direction, the vibration energy in each direction is absorbed by the shear deformation of the second deformable portion 13b.

Therefore, the spring constants of the respective vibration systems 14 and 15 in the respective directions are set based on the shear deformation, whereby the natural frequencies in the respective directions are set low.

On the other hand, when an excessive amplitude is generated in each of the vibrating systems 14 and 15 during the vibration in the direction perpendicular to the axis, the second deformable portion 13b of the elastic member 13 is reached when the amplitude exceeds a predetermined value. The inner end portion of the second deformation portion 13b is brought into contact with the surface of the rotation shaft S, and the second deformation portion 13b is compressed and deformed accordingly.

Since the spring constant at the time of compressive deformation is extremely larger than the spring constant at the time of shearing deformation, the natural vibration of the dynamic damper 10 in the state where the second deformable portion 13b is brought into contact with the rotating shaft S. It is moved to the higher number.

As a result, when the excessive amplitude is generated due to the resonance, the natural frequency is changed and the resonance state is released, whereby the occurrence of the excessive amplitude is suppressed, and the durability of the elastic member due to fatigue is reduced. Sexual deterioration is suppressed.

Next, another embodiment of the present invention will be described with reference to FIGS. In the following explanation,
The same parts as those in the previous embodiment are designated by the same reference numerals and the description is simplified.

Dynamic damper 20 shown in this embodiment
Is characterized in that the natural frequencies of the two vibration systems 14 and 15 are different from each other, and the rest of the configuration is almost the same as that of the previous embodiment.

In order to make the natural frequency different, in this embodiment, as shown in FIG. 2, the shape of the elastic member 21 constituting the other vibration system 15 is changed,
The spring constant of the other vibration system 15 is set to be large, and the projections 22 projecting along the axial direction of the rotation axis S are provided on the respective facing surfaces of the coating layer 16 of each of the mass members 12. The projections 22 are formed at predetermined intervals in the direction (at intervals of 90 degrees in this embodiment), and the projections 22 projecting from each coating layer 16 are opposed to each other at a predetermined distance (D). ing.

The dynamic damper 20 of the present embodiment thus constructed has two different resonance points because the natural frequencies of the two vibration systems 14 and 15 are different, and therefore a plurality of different natural frequencies are provided. It can be selectively used with respect to the rotation axis S of, and its versatility is enhanced.

On the other hand, in the present embodiment, at the time of vibration in the axial direction, one of the vibration systems, for example, the one vibration system 14 is in a resonance state, and the mass member 12 has an excessive amplitude in the axial direction. Also in this case, the other vibration system 15 is in a non-resonant state, and the mass member 12 is held in a state where the vibration is stopped.

Therefore, the mass member 12 is brought into contact with the other mass member 12 in the stopped state by the movement of the one mass member 12 in the axial direction due to the excessive amplitude described above.

The vibration of the one vibrating system 14 is caused by elastic deformation of the projections 22 of the mass members 12 when the mass members 12 come into contact with each other, elastic deformation of the elastic member 21 supporting the other mass member 12, or the like. The excessive amplitude is attenuated by absorbing the energy.

Alternatively, after both mass members 12 come into contact with each other, both vibration systems 14 and 15 are integrally vibrated, so that the mass and the spring constant are changed and the natural frequency is changed. It is also expected that the damping action of excessive amplitude due to the release of is.

Here, in the present embodiment, the contact of both mass members 12 is performed via the projection 22,
The elastic deformation of the protrusions 22 alleviates the impact at the time of contact and prevents the generation of impact noise.

It should be noted that the shapes, dimensions, etc. of the constituent members shown in the above embodiments are merely examples, and can be variously changed based on design requirements and the like.

For example, in each of the above-described embodiments, an example in which the elastic member 13 is constituted by the first deformable portion 13a and the second deformable portion 13b has been shown, but the first deformable portion 13a may be omitted.

As a method for making the natural frequencies of the two vibration systems 14 and 15 different, a method of changing the shape of the elastic member 21 to make the spring constant different has been described.
It is also possible to deal with it by changing the mass of 2.

[0058]

As described above, according to the first aspect of the present invention.
According to the dynamic damper described in (1), the mass member is divided into two vibration systems, and the elastic members are respectively supported by different elastic members to reduce the mass supporting load on each elastic member. The thickness can be reduced.

Therefore, it is possible to reduce the spring constant of the elastic member and suppress the natural frequency of the dynamic damper while suppressing the decrease in strength of the elastic member.

According to the dynamic damper of the second aspect of the present invention, in particular, the elastic member of each vibration system extends from the end of the fixed member along the axial direction of the rotary shaft. And a second deforming portion that extends from the end of the first deforming portion in a direction orthogonal to the axis of the rotating shaft and is connected to the inner surface of the mass member. The vibration energy is absorbed by the shear deformation of the first deformable portion and by the shear deformation of the second deformable portion with respect to the axial vibration.

Therefore, the spring constant of each vibration system in both directions is low, and the natural frequency can be lowered in any direction.

Further, when an excessive amplitude is generated in each vibration system during vibration in a direction perpendicular to the axis, when the amplitude exceeds a predetermined value, the second deformable portion of the elastic member and the rotary shaft are The second deformed portion is compressed and deformed by the contact, and the resonance state is released by shifting the natural frequency to the higher side due to the large spring constant at the time of this compressed deformation, thereby suppressing the occurrence of the excessive amplitude. It is possible to suppress deterioration of durability due to fatigue of the elastic member.

Further, according to the dynamic damper of the third aspect of the present invention, in particular, by setting the one vibration system and the other vibration system at different natural frequencies, the rotary shaft having different natural frequencies can be obtained. Can be used selectively, and its versatility can be enhanced.

When an excessive amplitude is generated in the axial direction in one of the vibration systems, the other vibration system is held in a non-resonant state so that the mass member that moves due to the excessive amplitude becomes a non-resonant mass member. The vibration energy is brought into contact with each other to absorb the vibration energy, whereby the excessive amplitude in the axial direction can be attenuated, and deterioration due to fatigue of the elastic member can be suppressed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a dynamic damper according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a dynamic damper according to another embodiment of the present invention.

FIG. 3 is a side view of a dynamic damper according to another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing one structural example of a conventional dynamic damper.

[Explanation of symbols]

 10 ・ 20 Dynamic damper 11 Fixing member 12 Mass member 13 ・ 21 Elastic member 13a ・ 21a First deformation part 13b ・ 21b Second deformation part 14 (One) vibration system 15 (Other) vibration system 16 Coating layer 22 Protrusion

Claims (3)

[Claims] 1. A fixed member attached to a rotary shaft, a mass member arranged so as to surround the rotary shaft at a predetermined interval, and an elastic member connecting the fixed member and the mass member. A dynamic damper characterized in that a pair of the mass member and the elastic member are provided at intervals in the axial direction of the rotating shaft so that two vibration systems are formed in the fixed member. 2. The elastic member includes a first deformable portion extending from an end portion of the fixed member along an axial direction of the rotating shaft, and a direction perpendicular to the axial line of the rotating shaft from the end portion of the first deforming portion. 2. The dynamic damper according to claim 1, wherein the dynamic damper includes a second deformable portion that extends to the inner surface of the mass member and is connected to the inner surface of the mass member. 3. The dynamic damper according to claim 1, wherein the one vibration system and the other vibration system have different natural frequencies.