JPH0249420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vibration isolator for reducing vibrations from a vibration source.

[Background Art] A vibration isolating device, generally called a vibration isolating rubber, is used, for example, in an engine mount of an automobile to absorb vibrations from an automobile engine and prevent the vibrations from being transmitted to the vehicle body.

As this vibration isolator, a structure has been proposed in which a hollow chamber of an elastic body is used as a liquid chamber, and this liquid chamber is divided through a passage restricting the flow of liquid filled inside the liquid chamber. The elastic body used in this case has a low dynamic spring constant, and the loss of the elastic body itself is low, but there is a resistance force based on internal friction when the liquid moves through the restricted passage to another liquid chamber during vibration. It has become possible to obtain large losses.

However, in such a vibration isolator, the elastic body that regulates the amount of displacement in the direction perpendicular to the axis, that is, in the rolling direction of the engine, is also made of a low-loss material. Therefore, this lateral damping was small, and vibration absorption was insufficient. Furthermore, if the elastic body provided with the hollow chamber is also made of a high-loss material, the dynamic spring constant at high frequencies will increase, and the transmission of noise will increase.

[Object of the Invention] Taking the above-mentioned facts into account, the present invention aims to provide a vibration isolating device that can sufficiently absorb vibrations in a direction perpendicular to the vibrations acting on the main elastic body.

[Summary of the Invention] In the vibration isolating device according to the present invention, the main elastic body in which the liquid chamber is provided is made of a low-loss material, and the secondary elastic body that receives vibrations in a direction perpendicular to the vibration absorption direction of the main elastic body is made of a main elastic body. It is made of a high-loss material with a loss coefficient larger than that of the body, which ensures the absorption of lateral vibrations.

[Embodiments of the Invention] FIG. 1 shows a first example of a vibration isolator to which the present invention is applied.
An example is shown.

A base plate 10 of this vibration isolator has a mounting bolt 12 hanging down from the center thereof, and is used for fixing to a cross member 14 of a vehicle body shown in FIG.

A main elastic body 16 whose axis is perpendicular is vulcanized and bonded on the base plate 10, and a flange 18, which is a hollow plate, is similarly vulcanized and bonded to the upper end of this main elastic body 16. A peripheral portion of a top plate 20 is fixed to the upper part of this flange 18. This top plate 20 and flange 18
A peripheral portion of the diaphragm 22 is sandwiched between the two. As a result, the diaphragm 22 forms an air chamber 23 between it and the central protrusion of the top plate 20, and the diaphragm 22 and the main elastic body 1
6 forms a liquid chamber 24 filled with liquid, for example, water.

Furthermore, the peripheral edge of a partition plate 26 is held between the upper end of the main elastic body 16 and the lower side of the diaphragm 22 . Therefore, the liquid chamber 24 is divided by the partition plate 26 into an upper liquid chamber 24A and a lower liquid chamber 24B. A cylindrical body 28 is fixed to the center of the partition plate 26, and its hollow hole is connected to the upper liquid chamber 24A and the lower liquid chamber 24A.
This is an orifice 30 that is a restricted passage that communicates with B.

A mounting hole 21 is formed in the top plate 20, and as shown in FIG. 2, an automobile engine 32 is mounted via a bracket 34 and fixed through the mounting hole 21.

A portion of the flange 18 is a connecting portion 36 that is bent vertically after protruding laterally, and a connecting portion 38 that is erected in the lateral direction of the base plate 10.
A sub-elastic body 40 is vulcanized and bonded between them. This secondary elastic body 40 receives vibration in a direction (direction of arrow Q) substantially perpendicular to the axial direction (direction of arrow P) of the vibration isolator, which is the main absorption direction of the main elastic body 16, and regulates its displacement. It's summery.

In addition, a displacement adjustment plate 41 is provided at the middle part of the main elastic body 1.
is buried.

Here, the hardness of the main elastic body 16 according to JIS is Hs = 35 ~
The secondary elastic body 40 is made of high elasticity rubber (tan δ = 0.1 to 0.3) with Hs = 60 to 75. Therefore, since the main elastic body 16 is a low-loss material, its dynamic spring constant is low, and because the secondary elastic body 40 is a high-loss material with a larger loss coefficient (tan δ) than the main elastic body, its dynamic spring constant is high. ing.

Next, the operation of this embodiment will be explained.

The base plate 10 is mounted on the cross member 14 and attached to the cross member 14 with mounting bolts 12.
is fixed to. The engine 32 is mounted on the top plate 20 via a bracket 34, and bolts (not shown) are applied to the mounting holes 21 to secure the engine 32.

When installing the engine 32,
Since its own weight acts on the top plate 20, the main elastic body 16 is deformed and the pressure in the lower liquid chamber 24B increases. This increased pressure is transmitted to the upper liquid chamber 24A via the orifice 30, and the diaphragm 22 is displaced in a direction that reduces the air chamber 23.

When the engine 32 is in operation, vibrations generated in the engine 32 mainly act in the direction of arrow P via the top plate 20. Therefore, the main elastic body 16 can absorb vibrations by a damping function based on internal friction. Since the main elastic body 16 is made of a low-loss material, it has a low dynamic spring constant and does not transmit large vibrations to the cross member 14.

The orifice 30 of the liquid chamber 24 has an improved vibration damping effect due to the damping effect based on the viscous resistance generated when the liquid passes through, and can absorb large vibrations even though it is made of a low-loss material.

Also, the lateral direction that occurs in the engine 32, that is, the arrow Q
For rolling vibration in the direction, the secondary elastic body 40
Since it is a high-loss material, it can absorb this accurately. Since the secondary elastic body 40 is made of a high-loss material, it has a large dynamic spring constant, but since no large dynamic spring is generated in the direction of the arrow Q, large vibration noises are not transmitted to the vehicle body.

As a specific experimental example, the main elastic body 16 has a composition of 100 natural rubber (NR), 50 FT carbon, 50 naphthenic process oil, 2 sulfur, and an accelerator (CBS: N-dichlorohexyl 2-benzothiazyl-
Sulfenamide) 1, secondary elastic body 40 is synthetic rubber (SBR) 100, HAF carbon 50, aromatic process oil 10, Sulfur 2, accelerator (CBS)
It was set to 1. This was used as a test piece with a cross-sectional area of 2 x 5 mm and a length of 30 mm. As a result of measurement at a temperature of 20 to 30°C, a frequency of 10 to 15 Hz, an amplitude of ±2%, and an initial strain of 15%, the tan δ of the main elastic body 16 was 0.07. The JIS hardness of the secondary elastic body 40 was 0.26, and the JIS hardness was Hs = 60, making it possible to effectively absorb vibrations.

Next, FIG. 3 shows a vibration isolating device according to a second embodiment of the present invention. In this vibration isolator, a cylindrical body 42 whose axis is perpendicular to the periphery of the base plate 10
is fixed, and the outer periphery of the main elastic body 16 is vulcanized and bonded to the upper end tapered portion 42A of this cylinder 42. The inner circumference of the main elastic body 16 is vulcanized and bonded to the block 44. This block 44 is fixed to the top plate 20.

Further, a partition plate 46 sandwiched between the cylindrical body 42 and the base plate 10 forms a liquid chamber 24 between the cylindrical body 42 and the main elastic body 16. Furthermore, a partition plate 46 whose periphery is sandwiched between the diaphragm 22 and the cylindrical body 42 separates the liquid chamber 24 between the upper liquid chamber 24A and the lower liquid chamber 24A.
A circular plate 48 is fixed to the lower surface of the partition plate 46 and has a stepped portion around the circumference, forming a ring-shaped orifice 30. This orifice 30 is connected to the upper liquid chamber 2 through a circular hole 50 formed in the partition plate 46 and a circular hole 52 formed in the disc 48.
4A and the lower liquid chamber 24B, forming a long orifice.

Furthermore, a diaphragm 60 is attached to the circular holes 58 formed in the partition plate 46 and the disc 48, so that vibrations generated during high frequency vibration can be absorbed by the volume change of the liquid chamber 24.

A secondary elastic body 40 is attached between the connecting portion 54 of the top plate 20 and a block 56 fixed to the outer periphery of the cylinder body 42.

In this embodiment as well, the main elastic body 16 is made of a low-loss material, and the auxiliary elastic body 40 is made of a high-loss material, so that vibrations not only in the direction of arrow P but also in the direction of arrow Q can be reliably absorbed. There is.

[Effects of the Invention] As explained above, the vibration isolator according to the present invention uses a main elastic body made of a low-loss material and a sub-elastic body made of a high-loss material, so that vibrations in a direction perpendicular to the vibration absorption direction of the main elastic body can be suppressed. It has an excellent effect that allows for reliable absorption.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of the vibration isolator according to the present invention, FIG. 2 is a front view showing the vibration isolator installed on a vehicle body, and FIG.
It is a sectional view showing an example. 10... Base plate, 16... Main elastic body, 20
...Top plate, 22...Diaphragm, 24...
Liquid chamber, 26... Partition plate, 30... Orifice, 32...
Engine, 40... Sub-elastic body, 42... Cylindrical body, 46...
Partition board.

Claims (1)

[Claims] 1. The hollow chamber of the main elastic body made of a low-loss material interposed between the vibration generating part and the vibration receiving part is used as a liquid chamber, and this liquid chamber is used as a passageway for restricting the flow of the liquid filled inside the liquid chamber. A secondary elastic body made of a high-loss material having a larger loss coefficient than the main elastic body is provided, and the main elastic body receives vibration in a direction perpendicular to the main elastic body to restrict displacement exceeding a predetermined value. Shaking device.