JP2003314615A - Dynamic damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic damper 1 assuring a high productivity and structured suitably to reduce the torsion vibrations. <P>SOLUTION: The dynamic damper is equipped with a mass 11 with the center of gravity located eccentrical nearer one end 11a in the axial direction and inserted into a hollow shaft 22 of a propeller shaft, a first resilient piece 12 installed on the peripheral surface of the mass 11 in a position nearer the end 11a and consisting of a rubber-form resilient material to be put in pressure contact with the inner surface of the hollow shaft 22, and a second resilient piece 13 installed on the peripheral surface of the mass 11 in a position nearer the other end 11a in the axial direction and consisting of a rubber-form resilient material to be put in pressure contact with the inner surface of the hollow shaft 22. The first resilient piece 12 is formed split in a plurality of segments in the circumferential direction and thereby is equipped with a lower spring constant than the second resilient piece 13. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic damper, which is incorporated in a hollow shaft such as a propeller shaft and reduces vibration and noise of the hollow shaft.

[0002]

2. Description of the Related Art In a vehicle, a propeller shaft for transmitting a driving force output from an engine via a transmission to a rear wheel has a dynamic damper built therein for the purpose of reducing vibration and noise.

FIG. 5 is a cross-sectional view showing a dynamic damper of this type according to the prior art, along with a part of a propeller shaft, taken along a plane passing through an axis. As shown in FIG. 5, a conventional propeller shaft dynamic damper 100 includes a metal sleeve 101 having an elastic film 102 formed of a rubber-like elastic material on the outer peripheral surface thereof, and a movable inner sleeve. It is composed of a metallic mass body 103 arranged and an elastic body 104 formed of a rubber-like elastic material and radially connecting the sleeve 101 and the mass body 103 at a plurality of circumferential positions.

In this dynamic damper 100, the outermost elastic film 102 is pressed against the inner peripheral surface of the hollow shaft 110 of the propeller shaft with an appropriate tightening margin, and the mass body 103 and the elastic body 104 in a predetermined vibration frequency range. The spring-mass system (sub-vibration system) configured by means to reduce the vibration and noise of the propeller shaft by a dynamic vibration absorbing action that resonates in a phase opposite to the input vibration.

[0005]

However, according to the conventional dynamic damper 100, it is necessary to vulcanize and bond a rubber-like elastic material to the outer peripheral surface of the sleeve 101 and between the sleeve 101 and the mass body 103, respectively. Therefore, the number of parts was large, and accordingly, many steps were required for manufacturing.

Further, a propeller shaft (hollow shaft 110)
Is generated in a twisting direction having a node at one point on the axial center as indicated by an arrow V in the drawing. However, FIG.
The conventional dynamic damper 100 shown in (1) has a structure that corresponds to vibration in the axial direction and the longitudinal direction, and does not have a structure that corresponds to gouging vibration.

The present invention has been made in view of the above problems, and a technical problem thereof is to provide a dynamic damper having a high productivity and a structure suitable for reducing gouging vibration. .

[0008]

As a means for effectively solving the conventional technical problems, the dynamic damper according to the invention of claim 1 has a center of gravity unevenly distributed toward one end in the axial direction and a hollow shaft to be subjected to vibration reduction. A mass body to be inserted into the inner periphery of the hollow body, and an elastic body made of a rubber-like elastic material provided on the outer peripheral surface of the mass body near the one end in the axial direction and the other end in the axial direction and pressed against the inner peripheral surface of the hollow shaft. With. Therefore, the resonance motion of the spring-mass system composed of the mass body and the elastic body can be generated in the gouging direction.

According to a second aspect of the present invention, there is provided a dynamic damper, wherein a mass body to be inserted into an inner circumference of a hollow shaft whose vibration is to be reduced and an outer peripheral surface of the mass body which is located at one end in the axial direction are provided. A first elastic body made of a rubber-like elastic material that is pressed against the peripheral surface, and a rubber-like elastic material that is provided on the outer peripheral surface of the mass body near the other end in the axial direction and pressed against the inner peripheral surface of the hollow shaft. A second elastic body is provided, and spring constants of the first elastic body and the second elastic body are different from each other. Therefore, the resonance motion of the spring-mass system composed of the mass body and the first elastic body can be generated in the rubbing direction.

[0010]

1 is a sectional view showing a preferred embodiment of a dynamic damper according to the present invention by cutting along with a part of a propeller shaft along a plane passing through an axis.
FIG. 3 is a cross-sectional view showing a preferred embodiment of the dynamic damper according to the present invention by cutting along a plane passing through the axis, and FIG. 3 is cutting along a plane perpendicular to the axis at the III-III ′ position in FIG. 4 is a sectional view cut along a plane perpendicular to the axis at the IV-IV 'position in FIG.

First, in FIG. 1, reference numeral 1 is a dynamic damper, and 2 is a propeller shaft of a vehicle. The propeller shaft 2 includes a stem 21 and a hollow shaft 22 integrally fixed to the end portion of the stem 21, and the dynamic damper 1 is built in the hollow shaft 22. As shown in FIG. 2, the dynamic damper 1 includes a mass body 11 inserted into the inner circumference of the hollow shaft 22 of the propeller shaft 2.
And a first elastic body 12 and a second elastic body made of a rubber-like elastic material which are provided on the outer peripheral surfaces of the mass body 11 near the one end in the axial direction and near the other end in the axial direction and are in pressure contact with the inner peripheral surface of the hollow shaft 22. 13 and 13.

Mass body 11 in dynamic damper 1
Is made of a metal material, has a diameter appropriately smaller than the hollow shaft 22 of the propeller shaft 2, and has a circular cross section perpendicular to the axis, as shown in FIG.

The mass body 11 has one end 11 in the axial direction with an annular step portion 113 formed on the outer peripheral surface of the intermediate portion in the axial direction as a boundary.
Large-diameter portion 111 in which a portion near a is formed to have a relatively large diameter
And a small diameter portion 112 having a relatively small diameter in a portion near the other end 11b in the axial direction. Therefore, the center of gravity G of the mass body 11 is located near the one end 11a in the axial direction, that is, on the large diameter portion 111 side.

The first elastic body 12 is integrally vulcanized and bonded to the outer peripheral surface of the large-diameter portion 111 of the mass body 11 near the one end 11a in the axial direction, and the second elastic body 13 is the small-diameter portion 112 of the mass body 11. Is integrally vulcanized and bonded to the outer peripheral surface near the other end 11b in the axial direction. And of these, the first elastic body 1
As shown in FIG. 3, a plurality of 2 is formed in a spoke shape at equal intervals in the circumferential direction, and the spring constant is set to a low value by such a divided shape in the circumferential direction.
On the other hand, the second elastic body 13 has an annular shape that is continuous in the circumferential direction as shown in FIG. 4, and has a thickness in the axial direction larger than that of the first elastic body 12. With a relatively large tightening margin of about 10 to 20% with respect to the wall thickness in the longitudinal direction,
The propeller shaft 2 is pressed against the inner peripheral surface of the hollow shaft 22. Therefore, the first elastic body 12
Let k1 be the spring constant of and k2 be the spring constant of the second elastic body 13, then k1 <k2.

The difference in the spring constant is due to the difference in the first elastic body 1.
Alternatively, the second elastic body 13 and the second elastic body 13 may be formed by molding rubber-like elastic materials different from each other.

Further, as described above, the first elastic body 1
2 has a lower spring constant than the second elastic body 13, and since the center of gravity G of the mass body 11 is located relatively closer to the first elastic body 12, the first and second elastic bodies 12, The resonance frequency of the spring-mass system composed of 13 and the mass body 11 is
It is sufficiently lower than the resonance frequency of the spring-mass system composed of the second elastic body 13 and the mass body 11, whereby the frequency at which the amplitude of the gouging vibration of the propeller shaft 2 becomes maximum. Is set to the area.

In the dynamic damper 1 of the present embodiment configured as described above, the mass body 11 is set in a vulcanization molding die (not shown), and the space between the outer circumference of the mass body 11 and the inner surface of the die. By filling the formed molding space with a molding rubber material, the first elastic body 12 and the second elastic body 13 are
It is manufactured by vulcanizing and adhering to the mass body 11 simultaneously with vulcanization molding. Therefore, since there is no metal sleeve as in the conventional structure of FIG. 5 described above, the number of parts is small, and the first elastic body 12 and the second elastic body 13 can be simultaneously molded by one mold. Also, the number of manufacturing steps is small, and the productivity can be improved.

The dynamic damper 1 is mounted by press-fitting the small diameter portion 112 of the mass body 11 into the inner periphery of the hollow shaft 22 of the propeller shaft 2 shown in FIG. Therefore, as described above, the outer peripheral end portion of the second elastic body 13 has a relatively large interference of about 10 to 20% with respect to the wall thickness in the longitudinal direction.
Since it is pressed against the inner peripheral surface of the dynamic damper 1, the dynamic damper 1 is prevented from being easily displaced due to vibration or the like.
Is firmly fixed.

Further, as in the conventional structure of FIG. 5 described above, the elastic film 10 formed on the outer peripheral surface of the metal sleeve 101.
Since the radial thicknesses of the first elastic body 12 and the second elastic body 13 can be made larger than those of No. 2, the propeller shaft 2 can be easily press-fitted into the hollow shaft 22.

When the propeller shaft 2 rotates, the vibration accompanying the rotation is generated around the joint portion at the tip of the stem 21 in the gouging direction indicated by arrow V ₂ in FIG. Then, in such a frequency range in which the amplitude of the gouging vibration V ₂ increases, the spring-mass system composed of the first elastic body 12 and the mass body 11 in the dynamic damper 1 resonates, and the phase of the vibration waveform is Since the input vibration has a phase opposite to the waveform of the gouging vibration, the peak of the amplitude of the input vibration can be reduced and the vibration and noise of the propeller shaft 2 can be effectively reduced by the dynamic vibration absorbing action.

Here, in the resonance frequency range of the spring-mass system composed of the first elastic body 12 having a high spring constant and the mass body 11, the second elastic body 13 having a high spring constant and the small diameter portion of the mass body 11 are provided. Since the spring-mass system due to the mass on the 112 side does not resonate,
The vibration displacement of the mass body 11 does not become a translational motion in the radial direction, and as shown by an arrow V ₁ in FIG.
It is vibrated and displaced in the gouging direction centered on the neighborhood. And
This dynamic damper 1 includes a small-diameter portion 11 of a mass body 11.
Since 2 is attached so as to face the stem 21 side, the resonance direction V ₁ corresponds to the input vibration direction V _2, and therefore, the dynamic vibration absorbing action can be efficiently exhibited.

In the illustrated embodiment, the mass body 11
Has a large-diameter portion 111 and a small-diameter portion 112 with the annular step portion 113 as a boundary so that the center of gravity G is eccentrically located toward the one end portion 11a in the axial direction. Not limited. For example, by forming the outer peripheral surface of the mass body 11 into a conical surface shape, or by forming the mass body 11 into a columnar shape and forming a hole in the inner circumference of the other end portion 11b, the center of gravity G can be formed at one end in the axial direction by another method. It may be unevenly distributed near the portion 11a.

In the illustrated embodiment, the first elastic body 12 is formed into a plurality of pieces which are completely separated in the circumferential direction. However, for example, the inner peripheral portion covers the outer peripheral surface of the mass body 11 in a film shape. It may be partially continuous in the circumferential direction, such as a continuous shape or a shape in which only the outer peripheral portion is circumferentially separated by a slit or a recess.

Further, even if the center of gravity G exists in the axial center, the mass body 11 resonates by making the spring constants of the first elastic body 12 and the second elastic body 13 different from each other. It is possible to cause the movement in the gouging direction, and conversely, when the mass body 11 is shaped such that the center of gravity G is displaced from the central portion in the axial direction as shown in the figure, the first elastic body 12 and the first elastic body 12 Even if the spring constants of the two elastic bodies 13 are the same, it is possible to cause resonance motion in the gouging direction.

[0025]

According to the dynamic damper of the first aspect of the present invention, since the elastic body made of the rubber-like elastic material is provided on the outer peripheral surface of the mass body, the number of parts is small,
The number of manufacturing steps can be reduced, productivity can be improved, and cost can be reduced. Further, since the center of gravity of the mass body is unevenly distributed toward one end in the axial direction, the resonance motion of the mass body is generated in the moulding direction, so that an efficient dynamic vibration absorbing action is exerted against the inputted mowing vibration. be able to.

According to the dynamic damper of the second aspect of the present invention, since the elastic body made of the rubber-like elastic material is provided on the outer peripheral surface of the mass body, the number of parts is small and the manufacturing process is also reduced. The productivity can be improved and the cost can be reduced. In addition, the resonance of the mass body is different due to the difference in spring constant between the first elastic body provided on the outer peripheral surface of the mass body near the one end in the axial direction and the second elastic body provided on the outer peripheral surface of the mass body near the other end in the axial direction. Since the motion is generated in the gouging direction, an efficient dynamic vibration absorbing action can be exerted against the gouging vibration input.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a preferred embodiment of a dynamic damper according to the present invention along with a part of a propeller shaft taken along a plane passing through an axis.

FIG. 2 is a cross-sectional view showing a preferred embodiment of a dynamic damper according to the present invention, taken along a plane passing through an axis.

3 is a cross-sectional view taken along line III-III ′ in FIG. 2 and taken along a plane perpendicular to the axis.

4 is a cross-sectional view taken along line IV-IV ′ in FIG. 2 and taken along a plane perpendicular to the axis.

FIG. 5 is a cross-sectional view showing a dynamic damper according to a conventional technique, along with a part of a propeller shaft, taken along a plane passing through an axis.

[Explanation of symbols]

1 Dynamic damper 11 mass 11a One end in the axial direction 11b Axial other end 111 Large diameter part 112 Small diameter part 113 annular step 12 First elastic body 13 Second elastic body 2 Propeller shaft 21 stem 22 hollow shaft G center of gravity

Claims (2)

[Claims] 1. A mass body (11) in which a center of gravity (G) is eccentrically located near one axial end (11a) and is inserted into the inner circumference of a hollow shaft (22) whose vibration is to be reduced, and a mass body (11) of this mass body (11). An elastic body (12, 13) made of a rubber-like elastic material, which is provided on the outer peripheral surface near the one end (11a) in the axial direction and near the other end (11b) in the axial direction and is pressed against the inner peripheral surface of the hollow shaft (22); , A dynamic damper characterized by including. 2. A mass body (11) to be inserted into the inner circumference of a hollow shaft (22) whose vibration is to be reduced, and the hollow body provided on an outer peripheral surface of the mass body (11) near one axial end (11a). The first elastic body (12) made of a rubber-like elastic material that is brought into pressure contact with the inner peripheral surface of the shaft (22), and the hollow provided on the outer peripheral surface near the other axial end (11b) of the mass body (11). Axis (2
2) a second elastic body (12) made of a rubber-like elastic material that is pressed against the inner peripheral surface of the second elastic body, and the first elastic body (12) and the second elastic body (13) have different spring constants. A dynamic damper characterized by that.