JP2013245802A - Dynamic damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic damper which changes a resonance frequency of a spring-mass resonance system in accordance with an increase in the number of revolutions and damps vibration over a wide range of the number of revolutions as a result, and also does not need to secure a space for moving a mass body in a radial direction.SOLUTION: A damper is mounted inside hollow shaft and includes a mounting and a plurality of elastic body springs and mass bodies on the circumference. The elastic body spring has an axial sectional shape which is inclined obliquely to a direction which is orthogonal to a center axial line of the damper. A rotary mass body which is rotated radially by a centrifugal force is assembled to the elastic body spring. When the rotary mass body is rotated radially by the centrifugal force, the elastic body spring is elastically deformed and the obliquely inclined shape of the elastic body spring rises toward the orthogonal direction. Thus, a spring constant becomes high by increasing a compression spring component of the elastic body spring.

Description

  The present invention relates to a dynamic damper according to a vibration damping technique. The dynamic damper according to the present invention is mounted, for example, inside a hollow propeller shaft in a vehicle such as an automobile, and attenuates bending vibration generated in the propeller shaft by the dynamic vibration absorbing action.

  Conventionally, as shown in FIG. 4, the dynamic damper 52 is mounted on the inner side of the hollow shaft 51, and is provided on the inner peripheral side of the mounting portion 53. There is known a dynamic damper 52 having an elastic body 54 and a mass body 55 provided on the inner peripheral side of the elastic body 54 (see Patent Document 1).

In the dynamic damper 52, a resonance system composed of a spring-mass having an elastic body 54 as a spring and a mass body 55 as a mass is set, and the resonance frequency of the spring-mass resonance system is set to a hollow shaft 51 as shown in FIG. It is possible to reduce the bending vibration by making it coincide with the resonance frequency f ₀ of the bending vibration occurring in the region, but in the regions f ₁ and f ₂ deviating from the resonance frequency, the vibration level is worsened (increased). There is.

  To solve the above problem, as shown in FIG. 6, the annular mass body 55 is divided on the circumference, and the spring constant of the elastic body 54 is changed by the radial movement of the mass body 55 due to the centrifugal force. ) Has been developed to change the resonance frequency of the spring-mass resonance system in response to an increase in the above), but this structure requires a space for moving the mass body 55 in the radial direction. Accordingly, there is a problem that a space for freely designing the elastic body 54 disposed on the outer peripheral side is reduced (see Patent Document 2).

Japanese Patent Laying-Open No. 2003-314615 (FIG. 5) JP-A-6-94075

  In view of the above points, the present invention can change the resonance frequency of the spring-mass resonance system in accordance with the increase in the number of rotations (frequency), and thereby can attenuate the vibration in a wide rotation number region. Another object of the present invention is to provide a dynamic damper that does not require a space for moving the mass body in the radial direction.

  In order to achieve the above object, a dynamic damper according to claim 1 of the present invention is a dynamic damper mounted on the inner side of a hollow shaft, the mounting portion being mounted on the inner peripheral side of the hollow shaft, In a dynamic damper having a plurality of circumferentially provided elastic spring portions provided on an inner peripheral side and a mass body provided on an inner peripheral side of the elastic spring portion, the elastic spring portion includes the dynamic damper. A rotating mass body having an axial cross-sectional shape inclined obliquely with respect to a direction perpendicular to the central axis of the rotating body, and a rotating mass body that rotates in a radial direction by centrifugal force is assembled to the elastic body spring portion. The elastic spring portion is elastically deformed when it is rotated in the radial direction by centrifugal force, and the slanted shape of the elastic spring portion is raised in the orthogonal direction. Wherein the more the compression spring component of the elastic body spring portion is increased at increased spring constant.

  The dynamic damper according to a second aspect of the present invention is the dynamic damper according to the first aspect, wherein the shape of the elastic spring portion inclined is a parallel four side whose upper side is displaced in one axial direction with respect to the bottom side. The rotating mass body has a weight portion provided at one end in the axial direction of the embedded portion embedded in the elastic body spring portion.

  The dynamic damper according to claim 3 of the present invention is the dynamic damper according to claim 2, wherein the weight portion is covered with an elastic body covering portion integrated with the elastic body spring portion. To do.

  In the dynamic damper of the present invention having the above-described configuration, each of the plurality of elastic spring portions on the circumference arranged between the mounting portion and the mass body is inclined with respect to a direction orthogonal to the central axis of the dynamic damper. That is, an inclination angle is set with respect to a direction perpendicular to the central axis of the dynamic damper. In addition, a rotating mass body that rotates in the radial direction by centrifugal force is assembled to the elastic spring portion.

  The spring component K of the elastic body spring portion in the initial state is divided into a compression spring component Kc and a shear spring component Ks depending on the setting of the inclination angle. When the rotating mass body rotates in the elastic body spring portion due to centrifugal force as the number of rotations increases, the inclination angle decreases and becomes close to vertical (right angle to the axis), so that Kc becomes Kc ′ and Ks becomes Ks ′. Respectively have a relationship of Kc <Kc ′, Ks> Ks ′. Originally, since the relationship between the compression and shear springs is Kc> Ks, K <K ′ (K ′ is the spring component of the elastic spring portion in the elastically deformed state), and the spring constant increases with the increase in the rotational speed. As a result, a higher action is obtained, and as a result, the resonance frequency of the spring-mass resonance system increases with the rotational speed. Accordingly, since the resonance frequency rises even in a region that deviates from the resonance frequency at the beginning, it is possible to attenuate the vibration in the region deviating from the initial.

  The slanted shape of the elastic spring part is typically a parallelogram or a substantially parallelogram in which the upper side is displaced in one axial direction with respect to the base, and the rotating mass body by centrifugal force as the number of rotations increases. Rotating behavior within the elastic body spring portion decreases the inclination angle of the left and right sides of the parallelogram and approaches the vertical (right angle to the axis), so that the parallelogram is elastically deformed to approach a rectangle. In order to elastically deform the elastic body spring portion in this way, the rotating mass body is provided with a weight portion at one end in the axial direction of the embedded portion embedded in the elastic body spring portion.

  That is, when the centrifugal force is applied, the weight portion provided at one end portion in the axial direction of the rotating mass body is displaced outward in the radial direction. Therefore, the rotating mass body behaves so that one end portion in the axial direction is displaced outward in the radial direction and the other end portion in the opposite axial direction is displaced inward in the radial direction. On the other hand, the parallelogram is a shape in which the upper side is displaced in one axial direction with respect to the bottom side. Therefore, when the rotating mass body rotates in the above direction, the parallelogram is elastically deformed in the form of approaching a rectangle.

  When the weight portion provided at one end of the rotating mass body in the axial direction protrudes from the elastic body spring portion in the axial direction, a mounting portion is disposed at an interval outward in the radial direction of the weight portion. In some cases, mass bodies are arranged at intervals inward in the radial direction. The attachment portion is attached to the inner peripheral surface of the hollow shaft. Therefore, in such a case, the weight portion also functions as a radial stopper that restricts the radial displacement of the attachment portion and the mass body to a certain amount. Accordingly, it is possible to prevent the elastic spring portion from being excessively compressed due to a large radial displacement of the mounting portion and the mass body, thereby extending the life of the elastic spring portion as a spring. The

  Further, at this time, by covering the weight portion with the elastic body covering portion integral with the elastic body spring portion, it is possible to suppress the weight portion from directly contacting the mounting portion and damaging the mounting portion. Is done. The rotating mass body including the weight portion is generally a part made of a rigid material such as metal in order to secure a predetermined mass.

  The present invention has the following effects.

  That is, in the present invention, as described above, if the rotating mass body behaves in the elastic spring portion due to centrifugal force as the number of rotations increases, the inclination angle of the elastic spring portion decreases and becomes nearly vertical. The constant increases, and the resonance frequency of the spring-mass resonance system increases with the rotational speed. Therefore, since the resonance frequency rises even in a region that deviates from the resonance frequency at the beginning, it is possible to attenuate the vibration in the region deviating from the initial. Further, the mass body is not divided on the circumference like the above-described prior art, and does not move in the radial direction even when centrifugal force is applied, and therefore, no space for movement is required. The rotating mass body is installed within the radial height of the elastic spring portion. Therefore, according to the present invention, the resonance frequency of the spring-mass resonance system can be changed in accordance with the increase in the number of rotations (frequency) according to the intended purpose. It is possible to provide a dynamic damper that can be damped and does not require a space for moving the mass body in the radial direction. Further, by covering the weight portion of the rotating mass body with the elastic body covering portion integral with the elastic spring portion, it is possible to suppress the weight portion from directly contacting the mounting portion and damaging the mounting portion.

1 is a partially cutaway perspective view of a dynamic damper according to an embodiment of the present invention. FIG. 2A is a half cut sectional view of the dynamic damper, wherein FIG. 2A is a half cut sectional view showing an initial state of the dynamic damper, and FIG. 2B is a half cut sectional view showing an operating state of the dynamic damper. Sectional sectional view of a dynamic damper according to another embodiment of the present invention Sectional view of a dynamic damper according to a conventional example A graph showing the relationship between frequency and vibration level Sectional view of a dynamic damper according to another conventional example

The present invention includes the following embodiments.
(1) In a dynamic damper composed of an elastic body spring part and a mass body divided and installed on the circumference, the elastic body spring part is inclined in the longitudinal section of the propeller shaft, and in the radial direction in the spring part by centrifugal force in the middle. A dynamic damper characterized by having a centrifugal mass that can rotate.
(2) The dynamic damper, wherein the centrifugal mass body is covered with a covering portion made of the same member as the elastic spring portion.

  Next, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a dynamic damper 11 according to an embodiment of the present invention. 2A shows an initial state of the dynamic damper 11 (a state where centrifugal force is not acting on the dynamic damper 11), and FIG. 2B shows an operating state of the dynamic damper 11 (the dynamic damper 11). Shows a state in which centrifugal force is acting.

  As shown in FIG. 2A, the dynamic damper 11 according to this embodiment is mounted on the inner side (inner peripheral side) 51 of a hollow shaft (for example, a hollow propeller shaft in a vehicle such as an automobile), and its dynamic vibration absorbing action. Thus, the bending vibration generated in the hollow shaft 51 is attenuated. The bending vibration is vibration in a direction orthogonal to or substantially orthogonal to the central axis 0 of the hollow shaft 51 (axis perpendicular direction).

  The dynamic damper 11 according to the embodiment includes an attachment portion 12 attached to the inner peripheral surface of the hollow shaft 51, and a plurality of elastic spring portions 16 on the circumference provided on the inner periphery side of the attachment portion 12. And a mass body 17 provided on the inner peripheral side of the elastic body spring portion 16.

  Of these, the mounting portion 12 has an annular mounting reinforcing member (fixing reinforcing member) 13 made of a rigid material such as metal, and an elastic body mounting made of a rubber-like elastic body on the outer peripheral surface of the mounting reinforcing member 13. A portion (elastic body fixing portion) 14 is adhered (vulcanized and bonded) over the entire circumference. The attachment portion 12 is fitted (fixed) to the inner peripheral surface of the hollow shaft 51 with a predetermined fitting allowance.

  The mass body 17 is formed into a cylindrical shape by a rigid material such as a metal, and is arranged so that the central axis 0 of the cylinder coincides with the central axis 0 of the hollow shaft 51 or the dynamic damper 11. The mass body 17 has a predetermined mass.

  As described above, a plurality of elastic body spring parts 16 are arranged on the circumference (for example, three on the circumference), each made of a rubber-like elastic body, and the inner circumferential surface of the mounting reinforcing member 13 and the mass body 17. Are connected to the reinforcing member for mounting 13 and the mass body 17 via annular elastic body connecting portions 15 and 18 respectively attached to the outer peripheral surface of each of them. The elastic body spring portion 16 and the elastic body connecting portions 15 and 18 are integrally formed, and in addition to these, the elastic body attaching portion 14 may be integrally formed. The elastic body spring portion 16 has a predetermined spring constant.

  The elastic body spring portion 16 is formed so as to extend in the radial direction when viewed from the axial direction, and the axial cross-sectional shape thereof is the center axis 0 of the dynamic damper 11 as shown in FIG. In other words, the inclination angle θ toward the one axial direction (to the right in the figure) with respect to the direction perpendicular to the central axis 0 of the dynamic damper 11 is inclined. Is set. Specifically, the inclined shape is a parallelogram or a substantially parallelogram in which the upper side 16b is displaced in one axial direction with respect to the base 16a.

  Each elastic spring portion 16 is assembled with a rotating mass body (centrifugal mass body) 21 that receives a centrifugal force and rotates in the radial direction.

  That is, this rotating mass body 21 is formed by integrally forming a weight portion 23 at one end 22a in the axial direction of the embedded portion 22 formed in a planar shape by a rigid material such as metal, and the embedded portion 22 is elastically formed. By being embedded in the body spring portion 16, the elastic body spring portion 16 is assembled. The embedded portion 22 is a flat plate having a planar rectangular shape, and a weight portion 23 having a predetermined weight is formed by rolling one side of the embedded portion into a roll shape over the entire width.

  One end portion 22a in the axial direction of the embedded portion 22 protrudes from the elastic spring portion 16 in one axial direction, and the other end portion 22b in the axial direction (left side in the figure) of the embedded portion 22 is an elastic spring portion. 16 protrudes from the other side in the axial direction. Accordingly, the axial length of the embedded portion 22 is set slightly larger than the axial length of the elastic spring portion 16, and the circumferential width of the embedded portion 22 is also the circumferential width of the elastic spring portion 16. It is set a little larger than. Therefore, since the embedded portion 22 divides the elastic spring portion 16 in the radial direction, the elastic spring portion 16 is separated from the outer peripheral side spring portion 16A disposed on the outer peripheral side by the embedded portion 22 and the inner peripheral side. And the inner peripheral side spring portion 16 </ b> B disposed on the embedded portion 22. The spring portions 16A and 16B may be integrally formed by providing a through hole (not shown) in the embedded portion 22.

  As shown in FIG. 2A, in the initial state before the rotation of the rotating mass body 21, one end portion 22a in the axial direction of the embedded portion 22 is more radially inward than the other end portion 22b in the axial direction. In other words, the rotating mass body 21 is disposed in an obliquely inclined direction with respect to the central axis 0 of the dynamic damper 11. The obliquely inclined direction may be a direction orthogonal to the obliquely inclined shape of the elastic body spring portion 16.

  In the dynamic damper 11 having the above-described configuration, a resonance system including a spring-mass in which the elastic body spring portion 16 is a spring having a predetermined spring constant and the mass body 17 is a mass having a predetermined mass is set. It is possible to reduce the bending vibration by matching the resonance frequency of the mass resonance system with the resonance frequency of the bending vibration generated in the hollow shaft 51, but the dynamic damper 1 is centrifuged as the hollow shaft 51 rotates. When the force is applied and increases, the weight portion 23 provided at one end portion in the axial direction of the rotating mass body 21 is displaced outward in the radial direction as indicated by an arrow X. Therefore, as shown in FIGS. 2A to 2B, the rotary mass body 21 has one end in the axial direction displaced radially outward (arrow X) and the other end in the opposite axial direction. Behaves in the radial direction so as to be displaced radially inward (arrow Y). On the other hand, the parallelogram which is the axial cross-sectional shape of the elastic body spring portion 16 is a shape in which the upper side 16b is displaced in one axial direction with respect to the base 16a. The inclination angle θ is reduced, and the parallelogram is elastically deformed in the form of a rectangle. Therefore, the radial compression spring component in the elastic body spring portion 16 is increased and the spring constant is increased. As a result, the resonance frequency of the spring-mass resonance system increases with the rotational speed. Therefore, since the resonance frequency rises even in a region that deviates from the resonance frequency at the beginning, it is possible to attenuate the vibration in the region deviating from the initial.

  Moreover, the mass body 17 is not divided on the circumference like the said prior art, and even if a centrifugal force acts, it does not move to radial direction, and the space for movement is not required. The rotating mass body 21 is installed within the radial height of the elastic body spring portion 16.

  Therefore, the resonance frequency of the spring-mass resonance system can be changed according to the increase in the rotation speed (frequency), and the vibration can be damped in a wide rotation speed region. Thus, it is possible to provide the dynamic damper 11 that does not need to secure a space for moving the shaft in the radial direction.

  Further, in the dynamic damper 11 having the above-described configuration, the weight portion 23 provided at one end portion in the axial direction of the rotating mass body 21 protrudes from the elastic body spring portion 16 in the axial direction, and the weight portion 23 is radially outside. Since the elastic body connecting portion 15 of the mounting portion 12 is arranged with a gap in the direction and the elastic body connecting portion 18 of the mass body 17 is arranged with a gap inward in the radial direction, the weight portion 23 is It functions as a radial stopper that regulates the radial displacement of the mounting portion 12 and the mass body 17 to a certain amount. Therefore, it is possible to suppress the attachment portion 12 and the mass body 17 from being greatly displaced in the radial direction and excessively compressing the elastic spring portion 16, thereby extending the life of the elastic spring portion 16 as a spring. Is possible.

  In this case, when there is a possibility that the weight portion 23 made of a rigid material such as a metal may come into contact with the elastic body connecting portions 15 and 18 and damage the elastic body connecting portions 15 and 18, the weight portion 23 is connected to the elastic spring as shown in FIG. It is conceivable to cover with the elastic body covering portion 24 integral with the portion 16, thereby suppressing the weight portion 23 from directly contacting the elastic body connecting portions 15 and 18 and damaging the elastic body connecting portions 15 and 18. It is possible to do. In the illustrated example, not only the weight portion 23 but also the other end portion 22 b in the axial direction of the embedded portion 22 is covered with an elastic body covering portion 25 integrated with the elastic body spring portion 16.

DESCRIPTION OF SYMBOLS 11 Dynamic damper 12 Mounting part 13 Mounting reinforcement member 14 Elastic body mounting part 15,18 Elastic body connection part 16 Elastic body spring part 16a Bottom 16b Upper side 16A Outer peripheral side spring part 16B Inner peripheral side spring part 17 Mass body 21 Rotating mass body 22 Embedded portion 22a One end portion in the axial direction 22b The other end portion in the axial direction 23 Weight portion 24, 25 Elastic body covering portion 51 Hollow shaft 0 Center axis θ Inclination angle

Claims (3)

A dynamic damper mounted on the inner side of the hollow shaft, the mounting portion mounted on the inner peripheral side of the hollow shaft, and a plurality of elastic spring portions on the circumference provided on the inner peripheral side of the mounting portion; In the dynamic damper having a mass body provided on the inner peripheral side of the elastic body spring portion,
The elastic body spring portion has an axial cross-sectional shape that is obliquely inclined with respect to a direction orthogonal to the central axis of the dynamic damper,
A rotating mass body that rotates in a radial direction by centrifugal force is assembled to the elastic spring portion,
When the rotating mass body behaves in a radial direction due to centrifugal force, the elastic spring portion is elastically deformed, and the obliquely inclined shape of the elastic spring portion is raised in the orthogonal direction. A dynamic damper, wherein a compression spring component of the elastic body spring portion is increased and a spring constant is increased. The dynamic damper according to claim 1,
The slanted shape of the elastic spring portion is a parallelogram or a substantially parallelogram in which the upper side is displaced in one axial direction with respect to the base.
The dynamic damper according to claim 1, wherein the rotating mass body is provided with a weight portion at one end in the axial direction of the embedded portion embedded in the elastic body spring portion. The dynamic damper according to claim 2,
The dynamic damper, wherein the weight portion is covered with an elastic body covering portion integral with the elastic body spring portion.

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