JP7327723B2 - Vibration absorbing mechanism - Google Patents

Description

TECHNICAL FIELD The present invention relates to a mechanism for suppressing vibration generated in a shaft member such as a propeller shaft.

2. Description of the Related Art A shaft-inserted dynamic damper that is installed on the inner peripheral side of a hollow propeller shaft in a vehicle such as an automobile has been conventionally proposed. A dynamic damper is a structure in which a ring-shaped mounting portion and a mass body located on the inner peripheral side of the mounting portion are connected by a plurality of elastic bodies. Patent Literature 1 discloses a dynamic damper having a structure in which a plurality of stoppers for restricting radial movement of a mass body are provided between a mounting portion and the mass body.

JP 2007-139041 A

Particularly in an environment where the shaft member rotates at high speed, there is a possibility that the eccentricity of the mass body due to the rotation of the shaft member will become significant. Therefore, it may not be possible to sufficiently reduce the vibration of the shaft member due to the unbalanced amount of the shaft member or bending resonance. In consideration of the above circumstances, a preferred aspect of the present invention aims to effectively reduce the vibration of the shaft member.

A vibration absorbing mechanism according to one aspect of the present invention includes a first dynamic damper and a second dynamic damper installed at different positions on the inner peripheral side of a hollow shaft member in the direction of the central axis of the shaft member. In the mechanism, each of the first dynamic damper and the second dynamic damper includes an annular mounting portion mounted on the inner peripheral side of the shaft member and a central axis of the mounting portion on the inner peripheral side of the mounting portion. and a plurality of elastic bodies connecting the mounting portion and the mass body on the inner peripheral side of the mounting portion, the first center of the mass body of the first dynamic damper The shaft and the second central axis of the mass body of the second dynamic damper are located on opposite sides of each other with respect to the central axis of the shaft member.

ADVANTAGE OF THE INVENTION According to this invention, the vibration of the shaft member by bending resonance can be reduced, suppressing the deterioration of the imbalance amount of a shaft member.

4 is a cross-sectional view illustrating the configuration of a vibration absorbing mechanism; FIG. 1A and 1B are a front view and a cross-sectional view of a dynamic damper; FIG.

Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the dimensions and scale of each element in each drawing are appropriately different from those of the actual product.

A: Embodiment FIG. 1 is a cross-sectional view of a vibration absorbing mechanism 100 according to a preferred embodiment of the present invention. The vibration absorbing mechanism 100 of this embodiment is a mechanism for reducing vibrations generated in the shaft member 10 . The shaft member 10 is, for example, a propeller shaft that is installed in a vehicle such as an automobile and transmits power from a prime mover. The shaft member 10 is a hollow elongated member formed in a cylindrical shape, and rotates around a central axis (hereinafter referred to as “rotational axis”) C. As shown in FIG. FIG. 1 shows the structure of a longitudinal section including the rotation axis C. As shown in FIG.

The vibration absorbing mechanism 100 includes a first dynamic damper 20a and a second dynamic damper 20b. Each of the first dynamic damper 20a and the second dynamic damper 20b is a shaft-insertion type dynamic vibration absorber installed on the inner peripheral side (that is, the internal space) of the shaft member 10, and suppresses vibration of the shaft member 10 due to bending resonance. to reduce

Specifically, the first dynamic damper 20a and the second dynamic damper 20b are arranged side by side on the inner peripheral side of the shaft member 10 with a space therebetween in the direction of the rotation axis C. As shown in FIG. That is, the first dynamic damper 20a and the second dynamic damper 20b are installed at different positions in the rotation axis C direction.

The structure of the first dynamic damper 20a and the structure of the second dynamic damper 20b are common. Therefore, in the following description, the first dynamic damper 20a and the second dynamic damper 20b will be collectively referred to as the "dynamic damper 20", and the individual description of each will be omitted as appropriate.

2A and 2B are a front view and a cross-sectional view illustrating the structure of the dynamic damper 20. FIG. The front view (left view) of FIG. 2 is a front view of the dynamic damper 20 as seen from the central axis X direction. The cross-sectional view (right view) of FIG. 2 is a cross-sectional view illustrating the structure of a vertical cross section (a cross section taken along the line aa) including the central axis X. As shown in FIG. As illustrated in FIG. 2, the dynamic damper 20 of this embodiment includes a mounting portion 21, a mass body 22, a plurality of elastic bodies 23, and a plurality of restricting portions 24. As shown in FIG.

The attachment portion 21 is an annular portion attached to the inner peripheral side of the shaft member 10, and is formed of an elastic material such as rubber. The dynamic damper 20 is fitted to the shaft member 10 with the outer peripheral surface of the mounting portion 21 in close contact with the inner peripheral surface of the shaft member 10 . A cylindrical outer pipe 25 is embedded in the mounting portion 21 . The outer pipe 25 is a reinforcing ring for securing the fitting force of the mounting portion 21 with respect to the shaft member 10, and is made of a highly rigid material such as metal. A central axis of the mounting portion 21 corresponds to the central axis X of the dynamic damper 20 .

The mass body 22 is a damper mass located on the inner peripheral side of the mounting portion 21 . The mass body 22 of this embodiment is a columnar structure made of a highly rigid material such as metal. The outer peripheral surface of the mass body 22 is covered with a coating film 26 made of an elastic material such as rubber. The outer peripheral surface of the coating film 26 faces the inner peripheral surface of the mounting portion 21 with a gap therebetween.

The plurality of elastic bodies 23 are damper springs (so-called rubber feet) that connect the mounting portion 21 and the mass body 22 on the inner peripheral side of the mounting portion 21, and are made of an elastic material such as rubber. The plurality of elastic bodies 23 are arranged side by side in the circumferential direction about the central axis X with a space therebetween. Specifically, each elastic body 23 extends radially across the inner peripheral surface of the mounting portion 21 and the coating film 26 that covers the mass body 22 . As can be understood from the above description, the mass body 22 is connected to the inner peripheral side of the mounting portion 21 via a plurality of elastic bodies 23 .

A plurality of restricting portions 24 are installed on the inner peripheral side of the mounting portion 21 . For example, each restricting portion 24 is formed of an elastic material such as rubber. Specifically, each restricting portion 24 is a protrusion protruding from the inner peripheral surface of the mounting portion 21 within the interval between two elastic bodies 23 adjacent to each other in the circumferential direction. Therefore, the plurality of restricting portions 24 are positioned around the mass body 22 when viewed from the central axis X direction.

The top surface of each restricting portion 24 faces the surface of the coating film 26 with a gap therebetween. In the above configuration, when the mass body 22 is eccentric due to the rotation of the shaft member 10, the surface of the coating film 26 covering the mass body 22 comes into contact with the restricting portion 24, and the displacement of the mass body 22 in the radial direction stops. . By restricting the displacement of the mass body 22 as described above, the possibility of breakage of each elastic body 23 is reduced. That is, each restricting portion 24 is a stopper that restricts radial movement of the mass body 22 .

In this embodiment, the mounting portion 21, the plurality of elastic bodies 23, the plurality of restricting portions 24, and the coating film 26 are integrally formed. However, each element may be formed separately and joined to each other.

As illustrated in FIG. 2, the central axis Y of the mass body 22 is eccentric (that is, offset) with respect to the central axis X of the mounting portion 21 by a predetermined eccentricity amount δ. That is, in the initial state where the dynamic damper 20 is not installed on the shaft member 10 , the mass body 22 is eccentric with respect to the mounting portion 21 . As exemplified in FIG. 2, the central axis Y of the mass body 22 is an axial line extending parallel to the central axis X with an eccentricity .delta. As can be understood from the above description, the plurality of elastic bodies 23 support the mass body 22 with the central axis Y eccentric to the central axis X of the mounting portion 21 .

Further, the central axis Y of the mass body 22 in this embodiment also corresponds to the central axis of the plurality of restricting portions 24 . In other words, the plurality of restricting portions 24 are eccentric with respect to the central axis X of the mounting portion 21 by the amount of eccentricity δ. In other words, the plurality of restricting portions 24 are installed concentrically with the mass body 22 .

FIG. 1 shows a central axis Y of the mass body 22 in the first dynamic damper 20a (hereinafter referred to as "first central axis Y1") and a central axis Y of the mass body 22 in the second dynamic damper 20b (hereinafter referred to as "second center axis Y1"). Axis Y2") is shown. The first central axis Y1 coincides with the central axis of the plurality of restricting portions 24 in the first dynamic damper 20a, and the second central axis Y2 coincides with the central axis of the plurality of restricting portions 24 in the second dynamic damper 20b.

As illustrated in FIG. 1 , the first dynamic damper 20 a and the second dynamic damper 20 b are concentrically installed on the inner peripheral side of the shaft member 10 . That is, the center axis X of the mounting portion 21 of the first dynamic damper 20a and the center axis X of the mounting portion 21 of the second dynamic damper 20b coincide with the rotation axis C of the shaft member 10. As shown in FIG.

On the other hand, the first central axis Y1 of the mass body 22 in the first dynamic damper 20a and the second central axis Y2 of the mass body 22 in the second dynamic damper 20b do not coincide with the rotation axis C of the shaft member 10. Specifically, the first central axis Y1 and the second central axis Y2 are located on opposite sides of each other with the rotation axis C of the shaft member 10 interposed therebetween. For example, in the step of press-fitting the first dynamic damper 20a and the second dynamic damper 20b into the shaft member 10, each direction of the first dynamic damper 20a and the second dynamic damper 20b (specifically, about the central axis X) angle in the circumferential direction) is adjusted.

For example, assume a Z-axis perpendicular to the rotation axis C as illustrated in FIG. The first central axis Y1 is an axis line separated from the rotation axis C by an eccentric amount δ in the first direction z1 along the Z axis. On the other hand, the second central axis Y2 is an axis line separated from the rotation axis C by an eccentric amount δ in a second direction z2 opposite to the first direction z1. As can be understood from the above description, the rotation axis C can also be said to be an axis equidistant from the first central axis Y1 and the second central axis Y2.

By the way, the natural frequency of the dynamic damper 20 in the direction perpendicular to the rotation axis C tends to decrease due to recent weight reduction of vehicles. Therefore, in a configuration in which a plurality of restricting portions 24 are not provided, there is a possibility that the mass body 22 will be excessively eccentric under the rotation speed in the normal range, resulting in breakage of each elastic body 23 . In this embodiment, since the movement of the mass body 22 in the radial direction is restricted by the restricting portion 24 as described above, damage to the elastic bodies 23 can be effectively prevented.

On the other hand, in order to realize a sufficient vibration absorbing action by the dynamic damper 20, it is necessary to secure a sufficient distance between the mass body 22 (coating film 26) and each regulation portion 24. FIG. However, in the configuration in which the distance between the mass body 22 and each of the restricting portions 24 is large, the deterioration of the overall unbalance amount of the shaft member 10 becomes significant when the shaft member 10 rotates at high speed. In this embodiment, as described above, the first central axis Y1 and the second central axis Y2 are positioned opposite to each other with the rotation axis C interposed therebetween. According to the above configuration, the unbalanced amount of the shaft member 10, which becomes particularly conspicuous during high-speed rotation, is offset by the first dynamic damper 20a and the second dynamic damper 20b. Therefore, vibration of the shaft member 10 due to bending resonance can be reduced while suppressing deterioration of the unbalance amount of the shaft member 10 .

B: Modifications Specific modification modes added to the above-exemplified forms are exemplified below. Two or more aspects arbitrarily selected from the following examples may be combined as appropriate within a mutually consistent range.

(1) In the above embodiment, the mass body 22 is covered with the coating film 26, but the coating film 26 may be omitted. In a configuration in which the coating film 26 is omitted, the outer peripheral surface of the mass body 22 comes into contact with the restricting portion 24 when the mass body 22 is eccentric.

(2) In the above embodiment, the configuration in which the structure of the first dynamic damper 20a and the structure of the second dynamic damper 20b are common was exemplified. There is no need to strictly match the structure. As long as the above-described effect of reducing the vibration of the shaft member 10 due to bending resonance while suppressing the deterioration of the unbalance amount of the shaft member 10 is realized, the structure of the first dynamic damper 20a and the second dynamic damper 20a can be changed. The structure of the damper 20b may be slightly different.

In addition, although the above-described form in which the eccentricity δ of the first central axis Y1 and the eccentricity δ of the second central axis Y2 with respect to the rotation axis C are basically suitable, the above-described effect is realized. The eccentricity .delta. of the first central axis Y1 and the eccentricity .delta. of the second central axis Y2 may differ slightly within the range.

(3) In the above embodiment, the shaft member 10 to which the vibration absorbing mechanism of the present invention is applied is illustrated as a propeller shaft of a vehicle such as an automobile, but the mechanism to which the present invention is applied is not limited to the above examples. The vibration absorbing mechanism of the present invention is applied to any mechanism that rotates a hollow shaft member.

100... Vibration absorbing mechanism,
10... Shaft member,
20 dynamic damper,
20a... first dynamic damper,
20b ... second dynamic damper,
21 ... Mounting portion,
22 ... mass body,
23... elastic body,
24... regulatory department,
25 ... outer pipe,
26 ... Coating film,
C... Rotating shaft,
X... central axis,
Y... central axis,
Y1... first central axis,
Y2 . . . second central axis.

Claims (2)

A vibration absorbing mechanism comprising a first dynamic damper and a second dynamic damper installed at different positions on the inner peripheral side of a hollow shaft member in the direction of the central axis of the shaft member,
each of the first dynamic damper and the second dynamic damper,
an annular attachment portion attached to the inner peripheral side of the shaft member;
a mass body that is eccentric with respect to the central axis of the mounting portion on the inner peripheral side of the mounting portion;
a plurality of elastic bodies that connect the mounting portion and the mass body on the inner peripheral side of the mounting portion,
A first center axis of the mass body of the first dynamic damper and a second center axis of the mass body of the second dynamic damper are positioned on opposite sides of each other with respect to the center axis of the shaft member. mechanism. each of the first dynamic damper and the second dynamic damper,
a plurality of stoppers installed on the inner peripheral side of the mounting portion and facing the outer peripheral surface of the mass body with a gap therebetween;
The vibration absorption according to claim 1, wherein central axes of said plurality of stoppers in said first dynamic damper coincide with said first central axis, and central axes of said plurality of stoppers in said second dynamic damper coincide with said second central axis. mechanism.

Images