JPH0632513Y2 - Anti-vibration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a vibration damping device that can be applied to a structure such as a cover that resonates and oscillates with an oscillating internal combustion engine.

[Prior art]

Of the noise generated from the engine mounted on a bicycle, etc.
It is conventionally known that the contribution of vibration noise from the cylinder head cover to the noise from the top is very high, and the contribution of vibration noise from the front cover to the noise from the front is very high. As a vibration isolation device for the cover, for example, in addition to providing a rib or the like on the vibrating surface of the front cover to provide rigidity, Japanese Patent Laid-Open No. 57-73330 has been proposed.

Even in the case of this publication, to the extent that it can be dealt with by changing the material of the front cover to a soft material with large vibration dipping such as nylon 66 and changing the rigidity of the material,
No more effective noise control measures have been taken.

Further, a structure such as a front cover is forcibly or resonatingly vibrated by the vibration generated by the engine itself. For example, a portion such as an engine block skirt has conventionally been internally provided with a ladder frame or the like. Although measures have been taken to increase the rigidity by providing a gearbox, when a transmission mechanism is installed inside such as the front cover, and various valve operating mechanisms are installed inside such as the head cover. However, since there is no space for providing such a reinforcing member, there is a problem in that vibration cannot be suppressed by such means.

[Problems to be solved by the invention]

By the way, according to an experiment conducted by the present inventor on each surface of the front cover, it was observed that the vibration mode having a strong influence on vibration and noise is the secondary bending vibration mode. Therefore, as in the above-mentioned publication, even if the material is changed to a soft material having a large vibration dipping, a sufficient vibration damping effect cannot be obtained, and the development of an effective vibration damping means is required. It's a reality.

In view of the above-mentioned conventional circumstances, the present invention was devised to solve the above problems. The frictional action between the vibration absorbing elastic bodies made up of a plurality of blocks and the vibration absorbing elastic body added to the frictional action. The purpose of the present invention is to provide a vibration damping device capable of reducing vibration and noise by a damping function as a dynamic damper composed of a weight and a weight.

[Means for solving problems]

In the vibration isolator according to the present invention which achieves the above object, the vibration absorbing elastic bodies divided into a plurality of blocks along the longitudinal direction of the vibrating surface are arranged in parallel so that the ends of adjacent blocks contact each other. Each block is pressed against the vibrating surface by a mounting bolt that fastens the block and the weight provided on the surface together.

[Action]

Therefore, in the vibration-absorbing elastic body 5, the bending vibration in a relatively low range, which is mainly the secondary bending vibration that affects the noise most, is divided into a plurality of blocks 4a, 4b, 4b, 4b along the longitudinal direction. It can be taken in and attenuated.

Moreover, due to the combined action of the vibration damping action due to the friction of the contact surface 9 where the ends of a plurality of adjacent blocks come into contact with each other, and the damping action of the weight 6 which independently presses each block 4 as a dynamic damper. It is possible to efficiently absorb the vibration of the vibrating surface 3 and suppress the generation of noise.

〔Example〕

Hereinafter, the drawings showing the present invention as an embodiment will be described.

As shown in the schematic perspective view of FIG. 3, a front cover 2 mounted on the front portion of the engine body 1 is provided at the front portion of the engine body 1 to drive the camshaft from the crankshaft, although not shown. It is configured to cover the transmission mechanism.

As shown in FIGS. 1 and 2, a vibration absorbing elastic body 5 divided into a plurality of blocks 4a, 4b, 4b, 4a in the longitudinal direction is linearly provided outside the plane portion 3 of the front cover 2. The vibration-absorbing elastic body 5 is provided by being arranged side by side.
Is divided into a plurality of blocks 4a, 4b, 4b, 4a that cover the antinodes of the secondary bending vibration of the vibrating surface 3 (planar portion). In order to divide into the plurality of blocks 4a, 4b, ..., Depending on the state of vibration, the vibrating surface can be treated as one-dimensionally vibrating. Further, it is preferable that the part divided into the blocks 4a and 4b is a part where the vibration damping action due to the friction generated at the contact surface 9 of each of the divided blocks becomes large. However, the present invention is not limited to this.

Each of the blocks 4a, 4b, 4b, 4a is formed of a vibration damping material (damping material) such as rubber having a predetermined elastic coefficient into a substantially square shape in a plan view, and is provided at a substantially central portion of the mounting bolt. A mounting hole through which 7 penetrates and a fitting hole that fits into the outer diameter of the boss portion 3a described later are provided. Each block 4 is a weight 6 provided on the surface of the block.
And the block 4 are tightened together by the mounting bolts 7 that are independently pressed against the vibrating surface 3 (flat surface portion) of the front cover for each block 4. The mounting bolts 7 are mounted on the flat surface portion 3 of the front cover. It is adapted to be screwed into each of the boss portions 3a protrudingly provided.

The blocks 4a, 4b, 4b, 4a are arranged side by side so that the ends of adjacent blocks come into contact with each other at a contact surface 9 with a predetermined frictional force, and the corners of the contact surface 9 are rounded. Since the side portions are prevented from being turned over due to friction, a substantially central portion in the thickness direction is formed on the contact surface 9 that comes into contact with a predetermined pressure.

That is, as shown in detail in FIGS. 1 and 2, the blocks 4a set on both ends are provided with the contact surface 9 only on one side,
Since the blocks 4b set on the center side are provided with the contact surfaces 9 on both sides, it is easy to set the number of blocks 4b that can be set on the center side according to the length of the front cover 2 in the longitudinal direction. is there. And each block 4a, 4b, 4
On the surfaces of b and 4a, weights 6 which also serve as pressing plates for pressing each block against the flat surface portion 3 with a predetermined pressure are provided, so that a pressing plate dedicated to the block pressure contact is omitted. There is an advantage that only the weight 6 can be provided so that the blocks can be pressed against each other. Moreover, the weight of the weight 6 is changed so that the central portion of the flat portion 3 having a large amplitude becomes heavy and becomes lighter as it goes to both sides having a small amplitude, and the weight becomes the most efficient over the longitudinal direction of the flat portion 3. Can be configured as
Further, the pressure on the contact surface 9 of each block is also changed so that the central side of the flat portion 3 having a large amplitude becomes strong and decreases toward both sides having a small amplitude, and the efficiency is most efficient over the longitudinal direction of the flat portion 3. It can be set to be pressure.

In addition, the weight 6 has a second weight when the weight is light and thin.
As shown in the figure, the surface of the block 4 may be integrally embedded in the upper surface of the block 4 without being provided separately from the block, but in this case as well, the volume of the vibration damping elastic body 5 forming the block 4 is It is necessary to secure a predetermined amount.

Further, each block 4 presses the weight 6 by the mounting bolt 7 and presses against the flat surface portion 3 so as to have a predetermined thickness, thereby increasing the vibration absorption rate and increasing the rigidity rate of itself to increase the vibration damping rate. When the weight 6 is formed in a circular shape as in the embodiment, the pressure on the contact surface 9 is highest at the position on the center line C of each block 4, and the weight from the center line C is increased. The pressure of the contact surface 9 can be made lower as the distance from the block 4 increases. Further, in the case of the quadrangular weight 6 along the quadrangle shape of the block 4, the contact surfaces 9 contacting each other can be widened. Contact surface 9 over a long distance along the direction
The pressure can be maintained substantially constant, and the rectangular blocks 4 can be pressed into contact with each other substantially uniformly.

Therefore, as shown in Fig. 4, block 4a and block 4b are
In the secondary bending vibration mode of the vibrating surface 3, the contact surfaces 9 where the ends of the blocks 4a and 4b come in contact with each other have their movement directions opposite to each other, and the friction energy of the contact surfaces 9 absorbs the vibration energy. Since the action is performed, the action of damping the vibration caused by this friction, the action of damping the vibration energy absorbed inside both blocks 4a and 4b, and the dynamic damper of the weight 6 that presses each block 4 independently. Fig. 5A
Since it is possible to absorb higher-order vibration modes including the first-order bending vibration mode shown in FIG. 5 and the second-order bending vibration mode shown in FIG. 5B, it is possible to suppress the vibration of the vibrating surface 3 and effectively prevent the generation of noise. .

Further, as shown in FIG. 6, a vibration damping elastic body 15 (damping material) made of rubber or the like having a predetermined elastic coefficient is adhered over the entire outer surface of the flat surface 3 of the front cover 2, and the vibration damping elastic body is A plurality of weight pieces 16 (iron material, etc.) having a predetermined weight are embedded in the front cover 2.
When the metal piece 16 vibrates in the vibration damping elastic body 15 as it vibrates, the metal piece 16 acts as a dynamic damper that absorbs the vibration energy of the front cover 2, and the primary vibration mode and the first vibration mode shown in FIG. 5 Vibration and noise can be reduced by absorbing higher order vibration modes including the secondary vibration mode shown in FIG. 5B.

7A and 7B, the front cover 17 is formed of a synthetic resin such as 66 nylon V, and the flat portion 19 of the resin front cover 17 is formed.
20 which is extremely rigid and lighter than metal
In this ceramic 20, the shape with the highest vibration damping effect can be selected according to the area and shape of the flat surface portion 19 of the front cover 17 and the size and type of the internal combustion engine. It is desirable to have a skeleton structure as shown in FIG.

As in this example, in the resin front cover 17, by embedding the ceramic 20 having extremely high rigidity in the flat surface portion 19 (vibration surface) where the vibration is largest, the resin front cover 17 can be By improving the rigidity of the flat portion 19, the primary vibration mode and the fifth vibration mode shown in FIG.
Vibration and noise can be reduced by absorbing higher-order vibration modes including the secondary vibration mode shown in FIG.

Although the above description has been made mainly for the front cover 2, the vibration isolator of the present invention has the same effect even if it is applied to the cylinder head cover.

[Effect of device]

In the vibration isolator according to the present invention, the vibration absorbing elastic bodies divided into a plurality of blocks along the longitudinal direction of the vibrating surface are arranged in parallel so that the ends of adjacent blocks contact each other, and are provided on the block and the surface. Since each block is pressed against the vibrating surface by the mounting bolts that tighten the
Bending vibration in a relatively low range, which is mainly secondary bending vibration that affects the most noise, can be taken in and damped by the vibration absorbing elastic body divided into a plurality of blocks along the longitudinal direction of the vibrating surface. Moreover, the vibration damping effect due to the friction of the contact surface where the ends of the adjacent blocks contact each other and the damping effect of the weight that independently presses each block as the dynamic damper are combined to effectively vibrate. The vibration of the surface can be absorbed and the generation of noise can be suppressed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a plan view of a front cover equipped with a vibration isolator of the present invention, FIG. 2 is a partially cutaway side view of FIG. FIG. 4 is a schematic perspective view showing the relationship between the engine body and the front cover, FIG. 4 is an operation explanatory view, FIG. 5A is a side view of the front cover showing a primary bending vibration mode, and FIG. 5B is a secondary bending. It is a side view of a front cover showing a vibration mode. 6 to 7 show another example, FIG. 6 is a side view of the front cover with a part thereof cut away, FIG. 7A is a plan view of the front cover, and FIG. 7B is FIG. 7A. FIG. 1 ... Engine body, 2 ... Front cover, 3 ... Flat surface (vibrating surface) 3a ... Boss portion, 4 ... Block, 5 ...
Vibration absorbing elastic body, 6 ... Weight, 7 ... Mounting bolt, 9 ...
… Contact surface.

Claims (1)

[Scope of utility model registration request] 1. A vibration absorbing elastic body divided into a plurality of blocks along the longitudinal direction of a vibrating surface is arranged in parallel so that the ends of adjacent blocks contact each other, and a weight provided on the block and the surface. An anti-vibration device in which each block is pressed against the vibrating surface with a mounting bolt that tightens together.