JPH10227333A - Dynamic damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the torsional vibration of the rotary section of an apparatus and suppress the generation of noises from a dynamic damper hub itself. SOLUTION: A first fitting section 121 and a tapered second fitting section 122 are formed bordering a circular step having the diameter larger than it on the peripheral tubular section 12 of a hub 10. A first damper unit 20 provided with a first mass body 21 and a first elastomer member 22 is provided on the outer periphery of the first fitting section 121. A second damper unit 30 provided with a second mass body 31 and a second elastomer member 32 is provided on the outer periphery of the second fitting section 30. The torsional direction characteristic frequency of the second damper unit 30 is set higher than the torsional direction characteristic frequency of the first damper unit 20.

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 dynamically absorbs torsional vibration generated in a rotating part of a device such as a sprocket and various types of rotating shafts by a resonance operation in a torsional direction.

[0002]

2. Description of the Related Art A rotating part of a device generates torsional vibration (vibration in a rotating direction) due to rotation due to various causes. For example, a camshaft or an injection pump in an internal combustion engine of an automobile or the like has a rotating body including a sprocket due to a lifting operation by a cam and a change in an internal pressure of the pump. To form a resonance system based on the spring constant due to the tension of the transmitting and receiving belt, a torsional resonance phenomenon occurs in a certain rotation speed range, which adversely affects the operation of the internal combustion engine, such as the combustion process, and changes in the load of the belt. There is a problem that becomes large. Therefore, conventionally, in order to reduce such torsional vibration of a sprocket or the like, it is known to mount a dynamic damper having a structure in which a hub and an annular mass body arranged on the outer periphery thereof are connected by an elastic body. With this dynamic damper, the resonance system consisting of a mass body and an elastic body resonates in the torsional direction at a phase angle different from the input vibration due to the input of torsional vibration in a predetermined frequency range, thereby exhibiting a dynamic vibration absorbing effect. Is what you do.

[0003]

However, this kind of dynamic damper has the following problems. (1) The frequency range in which vibration can be effectively absorbed is narrow. (2) A hub formed of a metal plate acts like a loudspeaker by transmitting vibrations and the like in the axial direction of a rotating shaft, and may generate radiated sound.

[0004] The present invention has been made under such circumstances, and its main technical problems are to effectively suppress torsional vibration of a rotating portion of equipment and to effectively suppress generation of noise. It is in.

[0005]

The above-mentioned conventional technical problems can be effectively solved by the present invention. That is, the dynamic damper according to the present invention has a first mounting portion formed on the base end side of the outer peripheral cylindrical portion and a larger diameter than the first mounting portion, and is provided on the open end side of the outer peripheral cylindrical portion. A cup-shaped hub having a formed second attachment portion, an annular first mass body concentrically arranged on the outer periphery of the first attachment portion, and the first mass body, A first damper unit made of a first elastomer member elastically connected to the mounting portion, an annular second mass body concentrically arranged on the outer periphery of the second mounting portion, and the second mass The first damper unit includes a second elastomer member elastically connecting a body to the second mounting portion, and includes a second damper unit having a different natural frequency. According to this configuration, the first and second damper units having different natural frequencies can absorb torsional vibration in a wide frequency range.

In a further preferred configuration of the present invention, a sliding member slidable between one or both of the opposing end surfaces between the opposing end surfaces of the first mass body and the second mass body. Intervened. As described above, since the first damper unit and the second damper unit have natural frequencies different from each other, the first damper unit and the second damper unit at the time of the torsional resonance of the first damper unit or at the time of the torsional resonance of the second damper unit. The first mass body and the second mass body are relatively displaced from each other in the circumferential direction, and accordingly, sliding with the sliding member occurs. For this reason, in addition to the damping action due to the internal friction of the first elastomer member or the second elastomer member, the damping action due to the sliding resistance is exhibited, and the damping force against vibration is increased.

According to another preferred configuration of the present invention, the outer peripheral cylindrical portion of the hub has a folded shape on the second mounting portion side toward the outer peripheral side and the first mass body side, and the folded portion and the first damper are provided. An annular space surrounded by the unit is opened to the outside of the hub through a small hole. Such a configuration is effective in absorbing sound emitted from the hub and noise from other sound sources, and is also effective in improving heat radiation from the first and second elastomer members.

[0008]

FIG. 1 shows a first embodiment of a dynamic damper according to the present invention, which is used as a means for reducing the torsional vibration of a sprocket of an internal combustion engine. In FIG. 1, reference numeral 1 denotes a sprocket whose inner peripheral portion 1a is fixed to a shaft end of a camshaft 2 of an internal combustion engine by a bolt 3, and a rotational driving force from a crankshaft of the internal combustion engine forms a chain or a belt 4. The rotation of the camshaft 2 is transmitted through the camshaft 2. The dynamic damper 5 of the present embodiment includes a hub 10 made of a metal plate, and first and second damper units 20 and 30 provided on the outer periphery of the hub 10 in the axial direction. The inner circumferential radial portion 11 is attached to the shaft end of the camshaft 2 by the bolt 3 so that the inner circumferential portion 1
It is fixed together with a.

The hub 10 has a cup shape having an inner peripheral radial portion 11 and an outer cylindrical portion 12 extending from the outer peripheral end thereof. Is formed with an annular stepped portion 123, with the annular stepped portion 123 as a boundary, a first mounting portion 121 on the base end 12 a side (the inner peripheral radial direction portion 11 side), and a larger diameter than the first mounting portion 121. A second mounting portion 122 on the side of the open end 12b (front side) is formed.

The first damper unit 20 is a metal sleeve 2 fitted on the outer peripheral surface of the first mounting portion 121.
A structure in which an annular first elastomer member 22 is integrally vulcanized and formed between opposed peripheral surfaces of an annular first mass body 21 and an annular first mass body 21 concentrically arranged on the outer peripheral side thereof. Have.
The second damper unit 30 is provided between the second mounting portion 122 and the peripheral surface of the annular second mass body 31 concentrically arranged on the outer periphery thereof. It has a structure in which the member 32 is integrally vulcanized.

The second mounting portion 122 of the outer cylindrical portion 12 of the hub 10 has a tapered shape whose diameter gradually increases toward the open end 12b of the outer cylindrical portion 12, and the second mounting portion 122 is provided on the outer circumferential side. Second mass body 31 in the damper unit 30 of FIG.
Has a tapered shape substantially corresponding to the second mounting portion 122, so that the second elastomer member 32 interposed therebetween also has a tapered shape. The second elastomer member 32 has a shear spring constant in the torsional direction higher than that of the first elastomer member 22 due to the fact that the second elastomer member 32 is on the outer peripheral side as a whole and the shape is different from the first elastomer member 22. The second mass body 31 has a smaller mass than the first mass body 21. For this reason, the torsional natural frequency of the second damper unit 30 is set higher than the torsional natural frequency of the first damper unit 20. Further, these natural frequencies are set in accordance with a frequency range in which torsional resonance occurs in a rotating body including the sprocket 1 and the camshaft 2 to be reduced.

According to the first embodiment, the sprocket 1 is provided by giving the first damper unit 20 and the second damper unit 30 different natural frequencies.
And the torsional resonance of the rotating body including the camshaft 2 is absorbed in a wide rotational speed range. Therefore, it is possible to suppress an adverse effect on operations such as a combustion stroke of the internal combustion engine and a load variation of the chain or the belt 4.

Further, even if the first elastomer member 22 of the first damper unit 20 is damaged due to excessive deformation, heat load, or the like, the tapered second mounting portion on the outer peripheral cylindrical portion 12 of the hub 10. Since the 122 and the second damper unit 30 function as stoppers for the first damper unit 20, the first mass body 31 does not fall off. Further, even if the second elastomer member 22 in the second damper unit 30 is damaged due to excessive deformation or the like, the second mounting portion 122 and the second mass body 31 in the outer cylindrical portion 12 of the hub 10 are not damaged. Since the opposed peripheral surface has a tapered shape whose diameter increases toward the open end 12b, the second mass body 31 does not drop off to the left in the drawing.

Next, FIG. 2 shows a second embodiment of the dynamic damper 5 according to the present invention. In addition to the same configuration as the above-described first embodiment, the first damper unit 20 Sliding member 40 between second damper units 30
Is provided. The sliding member 4
Numeral 0 denotes a disk made of a hard elastomer, synthetic resin or metal, and both sides of the outer peripheral portion 41 in the thickness direction (axial direction) are the first damper unit 2.
The first mass body 21 and the second mass body 31 of the second damper unit 30 are in slidable contact with the mutually facing end surfaces 21a, 31a of the second mass body 31. The hub 10 is held with an appropriate gap between the annular step portion 123 of the outer cylindrical portion 12 of the hub 10 and the sleeve 23 of the first damper unit 20.

According to the above configuration, when torsional vibration in a predetermined frequency range is input, the first damper unit 20 or the second damper unit 30 resonates in the torsional direction at a phase angle different from the input vibration. By doing so, dynamic vibration absorption for the torsional vibration is performed, and the vibration energy is attenuated by internal friction due to the repeated deformation of the first elastomer member 22 or the second elastomer member 33. At the same time, the outer peripheral portion 41 of the sliding member 40 is moved by the relative movement of the first damper unit 20 and the second damper unit 30 in the circumferential direction due to the resonance motion, so that the first and second mass bodies 21 and 31 slides in the circumferential direction with one or both of the opposing end faces 21a, 31a of the first elastomer member 22.
Alternatively, in addition to the internal damping action of the second elastomer member 33, a damping action due to sliding is provided, and excellent vibration damping properties are realized.

Next, FIG. 3 shows a third embodiment of the dynamic damper 5 according to the present invention. That is, instead of the disk-shaped sliding member 40 in the above-described second embodiment, an axial center is used. The configuration is such that an elastomeric sliding member 50 having a plurality of lips 52 extending concentrically around O is provided. The sliding member 50 has an end surface 31 of the second mass body 31 on the first damper unit 20 side of the second damper unit 30.
a, and a plurality of lips 52 protruding from the base portion 51 are circumferentially slidable with the end surface 21a of the first mass body 21 of the first damper unit 20 on the side of the second damper unit 30. It is movably contacted. Grease 53 is interposed between the lips 52.

According to the above configuration, at the same time as the dynamic damping by the first damper unit 20 or the second damper unit 30 is performed, each lip 51 of the sliding member 50 is moved by the first damper unit due to the resonance motion. With the relative displacement of the damper unit 20 and the second damper unit 30 in the circumferential direction, the end face 2 of the first mass body 21 of the first damper unit 20 is changed.
1a in the circumferential direction and the torsional vibration is attenuated.

In FIG. 3, the base 51 of the sliding member 50 is shown.
Is fixed to the second mass body 31 side, and the lip 52 is in sliding contact with the first mass body 21. Conversely, the base portion 51 is fixed to the first mass body 21 side, Even if the lip 52 is brought into sliding contact with the second mass body 31, the same effect can be obtained.

Next, FIG. 4 shows a fourth embodiment of the dynamic damper 5 according to the present invention. In this embodiment, the second mounting portion 122 of the outer peripheral tubular portion 12 of the hub 10 is connected to the open end 12 b of the outer peripheral tubular portion 12.
From the outer peripheral radial direction part 124 which is developed to the outer peripheral side,
It is formed so as to be folded back to the first mass body 21 side,
As in the first to third embodiments, the tapered shape gradually increases in diameter toward the front side. And a folded back portion including the second mounting portion 122 and the outer peripheral radial portion 124;
An annular space S surrounded by the first damper unit 20
Are opened to the front side of the hub 10 through a plurality of small holes 124a formed in the outer peripheral radial portion 124 at predetermined intervals in the circumferential direction.

First and second damper units 20, 30
Has the same configuration as the above-described first to third embodiments. That is, in the first damper unit 20, the sleeve 23 is fitted on the outer peripheral surface of the first mounting portion 121 on the base end 12a side of the outer cylindrical portion 12 of the hub 10, and the second damper unit Reference numeral 30 denotes a tapered shape in which the inner peripheral surface of the second mass body 31 substantially corresponds to the second mounting portion 122 of the hub 10, and the second elastomer member 32 is formed by the outer peripheral surface of the second mounting portion 122. And the second mass body 3
1 is integrally vulcanized and bonded to the inner peripheral surface.

The first damper unit 20 and the second damper unit 30 are given different natural frequencies, so that the resonance of the rotating body including the sprocket 1 and the camshaft 2 in the torsional direction is performed in a wide rotational speed range. Can absorb vibration. Also, even if the first elastomer member 22 of the first damper unit 20 is broken, the second mounting portion 122 and the second damper unit 30 of the hub 10 serve as a stopper for the first damper unit 20. Since the first mass body 31 does not fall off, even if the second elastomer member 22 of the second damper unit 30 is damaged, the outer cylindrical portion 12 of the hub 10 is damaged. Since the opposed peripheral surface between the second mounting portion 122 and the second mass body 31 in the above has a tapered shape in which the diameter increases toward the open end 12b side, the second mass body 31 may fall off. There is no.

According to the fourth embodiment, the second mounting portion 122 and the outer peripheral radial portion 12
An annular space S surrounded by a folded portion including the first damper unit 20 and the first damper unit 20 is connected to the hub through a plurality of small holes 124a formed in the outer peripheral radial portion 124 at predetermined intervals in the circumferential direction. By being open to the front side of 10, the sound radiated from the hub 10 and noise from other sound sources can be effectively absorbed. This is because a plurality of small holes 124a
Opening reduces the amount of sound radiation when the hub 10 vibrates in the axial direction, and reduces the space S and the small holes 124a.
This is because a kind of Helmholtz resonator can be configured to perform a sound absorbing function based on Helmholtz's resonance theory.

Further, as described above, the first elastomer member 22 and the second elastomer member 32 convert a part of kinetic energy into heat by internal friction, that is, the first and second damper units. Although the heat is generated due to the repeated deformation due to the resonance motion of the hubs 20 and 30, the small holes 124 a formed in the outer peripheral radial portion 124 of the hub 10 allow the air to flow between the first and second damper units 20 and 30. As a result, the heat is efficiently released to the outside. For this reason,
The deterioration of the first and second elastomer members 22, 32 due to heat is effectively prevented.

As shown in the fifth embodiment in FIG. 5, a plurality of rows of the small holes 124a of the outer peripheral radial portion 124 of the hub 10 may be formed at different positions in the radial direction.

In the sixth embodiment shown in FIG. 6, the second mounting portion 122 has a tapered shape in which the inclination direction is opposite to that in FIGS. 4 and 5, that is, a tapered shape in which the diameter gradually decreases toward the front side. The sound pressure of radiated sound is reduced by reducing the area of the outer peripheral radial portion 124 itself, in addition to the sound reducing effect based on the above-described principle.

Further, the seventh embodiment shown in FIG. 7 has features of both the embodiment shown in FIG. 4 and the embodiment shown in FIG. That is, the annular space S surrounded by the folded portion of the hub 10 including the outer peripheral radial portion 124 and the second mounting portion 122 and the first damper unit 20 is provided at the outer peripheral radial portion 124 at a predetermined circumferential interval. The disk-shaped sliding member 40 is opened to the front side of the hub 10 through a plurality of small holes 124a formed in the first damper unit 20 and the second damper unit 30. Of the outer peripheral portion 41 of the first damper unit 20
The first mass body 21 and the second mass body 31 of the second damper unit 30 are in slidable contact with the mutually facing end surfaces 21a, 31a.

Therefore, in this embodiment, the first and second damper units 20 having different natural frequencies are used.
30 to increase the vibration absorbing area and increase the sliding member 4
Thus, the vibration attenuation is improved by zero, and the noise reduction effect and the heat radiation effect by the small holes 124a are realized. Sliding member 4 in this case
0 may be replaced by a lip-shaped sliding member 50 as shown in FIG.

The dynamic damper 5 according to each of the illustrated embodiments is typically mounted on the sprocket 1 as shown in FIG. 1, but the present invention is not limited to this.
For example, the present invention can be applied as a vibration reducing unit for various rotating bodies that generate torsional vibration such as a pulley.

[0029]

According to the dynamic damper of the present invention, the following effects are realized. (1) The frequency range in which vibration can be effectively absorbed is widened, and the vibration absorption performance is improved. (2) The sound radiated from the hub due to the transmission of the vibration in the axial direction of the rotating shaft or the like can be reduced by the small holes formed in the hub. (3) The damping force against vibration is improved by the sliding member. (4) Due to the small holes formed in the hub, heat radiation from the elastomer member is good, and deterioration of the elastomer member is suppressed.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a first embodiment of a dynamic damper according to the present invention, cut along a plane passing through an axis together with a sprocket and a camshaft of an internal combustion engine.

FIG. 2 is a half sectional view showing a second embodiment of the dynamic damper according to the present invention by cutting along a plane passing through an axis.

FIG. 3 is a half sectional view showing a third embodiment of the dynamic damper according to the present invention by cutting along a plane passing through an axis.

FIG. 4 is a half sectional view showing a fourth embodiment of the dynamic damper according to the present invention by cutting along a plane passing through an axis.

FIG. 5 is a half sectional view showing a fifth embodiment of the dynamic damper according to the present invention by cutting along a plane passing through an axis.

FIG. 6 is a half sectional view showing a sixth embodiment of the dynamic damper according to the present invention by cutting along a plane passing through an axis.

FIG. 7 is a half sectional view showing a seventh embodiment of the dynamic damper according to the present invention by cutting along a plane passing through an axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sprocket 2 Camshaft 3 Bolt 4 Chain or belt 5 Dynamic damper 10 Hub 11 Inner diameter part 12 Outer part cylindrical part 121 First attachment part 122 Second attachment part 123 Annular step part 124 Outer diameter part 124a Small Hole 20 First damper unit 21 First mass body 21a, 31a Opposing end face 22 First elastomer member 23 Sleeve 30 Second damper unit 31 Second mass body 32 Second elastomer member 40, 50 Sliding member 41 outer peripheral part 51 base part 52 lip 53 grease S space

Claims (4)

[Claims] 1. A first mounting portion (121) formed on the base end (12a) side of an outer peripheral cylindrical portion (12), and a diameter larger than the first mounting portion (121), and Tubular part (1
2) a cup-shaped hub (10) having a second mounting portion (122) formed on the open end (12b) side, and concentrically arranged on the outer periphery of the first mounting portion (121). A first damper comprising an annular first mass body (21) and a first elastomer member (22) for elastically connecting the first mass body (21) to the first mounting portion (121); A unit (20), an annular second mass body (31) concentrically arranged on the outer periphery of the second attachment part (122), and the second mass body (31) is attached to the second attachment part by the second attachment part. A second elastomer member (32) elastically connected to the portion (122); and a second damper unit (30) having a different natural frequency from the first damper unit (20). Dynamic damper. 2. The device according to claim 1, wherein the first mass body (21) and the second mass body (31) are provided between the opposed end faces (21a, 31a) of the first mass body (21) and the second mass body (31).
A dynamic damper comprising a sliding member (40, 50) interposed between one or both of 1a and 31a). 3. The second mounting portion (1) of the outer cylindrical portion (12) of the hub (10) according to claim 1 or 2,
22) has a folded shape toward the outer peripheral side and toward the first mass body (21), and an annular space (S) surrounded by the folded portion and the first damper unit (20) has a small hole (1).
24. A dynamic damper characterized by being open to the outside of the hub (10) via 24a). 4. A dynamic damper according to claim 1, wherein the hub (10) is mounted concentrically on the sprocket (1).