JPH0434018B2 - - 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 automobile engine mount to absorb vibrations from the automobile engine and prevent them from being transmitted to the vehicle body.

Two vibration damping liquid chambers are provided as this vibration isolator, and the vibration from the vibration source is transmitted as a contraction force to one liquid chamber, and the liquid in this liquid chamber is moved to the other liquid chamber via a restriction passage. A structure has been proposed in which vibrations are absorbed by a resistance force based on internal friction.

However, in this vibration isolator, when the input vibration is high frequency, the amplitude is small and the restriction passage becomes clogged, the internal pressure rises and the spring constant becomes high. As a result, the transmission rate of vibration increases, causing the ride comfort of the vehicle to deteriorate.

As a countermeasure to this problem, a vibration isolator that absorbs high-frequency vibrations has been proposed, but it is difficult to obtain a large loss factor with this vibration isolator.

[Object of the Invention] Taking the above-mentioned facts into consideration, an object of the present invention is to provide a vibration isolating device that can appropriately attenuate even high-frequency vibrations and obtain a large loss factor.

[Summary of the Invention] In the vibration isolating device according to the present invention, a hollow chamber mainly for vibration absorption made of a hollow molded body of an elastic material is used as a liquid chamber. It is divided into small liquid chambers arranged in series.
These restriction passages have annular longitudinal axes. Further, one of the plurality of restriction passages has a larger cross-sectional area than the other one, and is arranged closer to the vibration source than the other one. As a result, the restriction passage with a small cross-sectional area attenuates large low-frequency amplitudes due to resistance during fluid flow, and the restriction passage with a large cross-sectional area absorbs small high-frequency amplitudes with a large loss factor due to liquid column resonance within the restriction passage. I'm starting to be able to do it. By changing the shape and volume of this restriction passage with a large cross-sectional area, the frequency of the vibration to be damped can be adjusted as desired.

In particular, in the present invention, since the restriction passages for absorbing low-frequency vibrations and high-frequency vibrations have an annular longitudinal axis, they are more effective than short restriction passages that are simply formed with through holes in the partition plate. Can absorb low frequency vibrations and high frequency vibrations. When restricting passages with long axes are provided in series like this, vibrations are transmitted to the other liquid chamber through the control passage placed on the vibration source side, that is, the restriction passage facing the liquid chamber that expands and contracts due to vibration. In some cases, vibrations are difficult to transmit or not transmitted at all. Therefore, in the present invention, a restriction passage for absorbing high-frequency vibrations with a large cross-sectional area is arranged on the side of the vibration source, and when low-frequency vibrations occur, the vibration is reliably transmitted to the restriction passage for absorbing low-frequency vibrations with a small cross-section area, thereby absorbing the vibration. People are starting to do this.

[Embodiments of the Invention] FIG. 1 shows a sectional view of a vibration isolator to which the present invention is applied. This vibration isolator has come to be used in automobiles as an engine mount.

The bottom cylinder 10 of this vibration isolator is caulked and fixed to the peripheral edge of an inner herring plate 12 at an axially intermediate portion. This ring plate 12 holds the periphery of the lower diaphragm 14 between it and a stepped portion 10A formed directly below. This lower diaphragm 14 forms an air chamber 16 between it and the bottom plate 10B of the bottom cylinder 10. The air vertebra 16 may communicate with the outside by forming a through hole in the bottom plate 10B.

The upper end of the bottom tube 10 is brought into contact with the lower surface of the ring plate 18, and is fixed together with the ring plate 18 by caulking to the lower end of the connecting tube 20.

The upper end of the connecting tube 20 is widened, and the lower end of rubber 22, which is the main vibration absorber, is vulcanized and bonded. It is also possible to use other elastic materials in place of rubber 22. The upper end of this rubber 22 is connected to the base plate 24.
The bolt 2 is attached to the base plate 24 by vulcanization.
6 is fixed. The base plate 24 is used to mount an engine (not shown), and the engine is fixed to the base plate 24 with bolts 26.

A flange 28 is fixed to the outer circumference of the connecting tube 20, and a circular hole 3 formed in the flange 28
0, the flange 28 is supported on the vehicle body by passing through a bolt (not shown) that stands upright from the vehicle body and then screwing into the nut.

The ring plate 12 and the ring plate 18
Both upper and lower ends of a cylindrical diaphragm 32 are vulcanized and bonded between the cylindrical diaphragm 32 and the inner periphery of the bottom cylinder 10, and an air chamber 34 is formed between the cylindrical diaphragm 32 and the inner periphery of the bottom cylinder 10. Like the air chamber 16, this air chamber 34 may be communicated with the outside by forming a through hole in the bottom tube 10.

A sealed space formed by the base plate 24, the rubber 22, the cylindrical diaphragm 32, and the lower diaphragm 14 is a liquid chamber into which liquid such as water is injected.

The periphery of the upper partition plate 36 is clamped and fixed between the ring plate 18 and the connecting cylinder 20. This upper partition plate 36 is made of a steel plate having a cylinder part 38 and a ceiling part 40 rising at right angles to the center thereof, and divides the liquid chamber into an upper liquid chamber 37A and a middle liquid chamber 37B.

An abutment plate 42, which is also shown in detail in FIG. 2, is fixed to the inside of the upper partition plate 36. This abutment plate 42 has a circular hole 44 bored in the center thereof, and a cylindrical body 46 is connected at right angles to the outer circumference thereof. The connecting portion between the abutment plate 42 and the cylindrical body 46 is bent to have an L-shaped cross section, and forms a recess 48 formed around the axis of the abutment plate 42 over almost the entire circumference. This recessed portion 48 is approximately C-shaped when viewed in the axial direction of the contact plate 42, and when the cylindrical body 46 is fixed to the inner circumference of the cylindrical portion 38, a ring is formed between the cylindrical portion 38 and the ceiling portion 40. form a space. This space communicates with the upper liquid chamber 37A and the middle liquid chamber 37B via communicating holes 50 and 52 formed in the ceiling part 40 and a part of the recessed part 48, respectively.

Therefore, the C-shaped space formed between the upper partition plate 36 and the recess 48 serves as an orifice 54 that is a restriction passage that allows communication between the upper liquid chamber 37A and the middle liquid chamber 37B.

The periphery of a lower partition plate 56 is clamped and fixed between the lower diaphragm 14 and the cylindrical diaphragm 32. This lower partition plate 56 has a cylindrical part 58 and a ceiling part 60 like the upper partition plate 36, and divides the liquid chamber into an intermediate liquid chamber 37B and a lower liquid chamber 37C. As a result, the upper liquid chamber 37A, the middle liquid chamber 37B, and the lower liquid chamber 37C are arranged in series. Further, a contact plate 62 similar to the contact plate 42 is fixed to the lower partition plate 56, and an orifice 64 is formed and a communication hole 66 bored in the lower partition plate 56 and the contact plate 62 are fixed to the lower partition plate 56.
It communicates with the middle liquid chamber 37B and the lower liquid chamber 37C via a communication hole 68 bored into the middle liquid chamber 37B and the lower liquid chamber 37C.

Here, the orifice 54 is disposed closer to the vibration source than the orifice 64, that is, closer to the base plate 24, and the orifice 54 has a larger cross-sectional area than the orifice 64.

Next, the operation of this embodiment will be explained.

The flange 28 is fixed to the vehicle body via bolts (not shown) that stand upright from the vehicle body, and the assembly is completed by mounting the automobile engine onto the base plate 24 with the bolts 26.

When the engine is installed, the weight of the engine acts on the base plate 24, so the pressure in the upper liquid chamber 37A increases. This increased pressure is transmitted to the middle liquid chamber 37B via the orifice 54 and to the lower liquid chamber 37C via the orifice 64, so that the cylindrical diaphragm 32 or the lower diaphragm 14
Alternatively, the air chamber 16 is displaced in a direction that reduces the size of the air chamber 16.

When the engine is in operation, vibrations generated in the engine are transmitted through the base plate 24. The rubber 22 can absorb vibrations by a damping function based on internal friction.

When the frequency of vibration is low, the amplitude is large;
The vibration damping effect is improved by the damping effect based on the viscous resistance generated when passing through the restricted passage having a small cross-sectional area, that is, the orifice 64. In this case, orifice 5
4 has a large cross-sectional area, so there is almost no damping effect in this part.

This low frequency and large amplitude vibration absorption is achieved through the orifice 6.
4 is C-shaped and a long restricted passage is formed, so the vibration absorption effect is large. Further, when attaching the contact plate 62 to the lower partition plate 56 by welding or the like, the length of the orifice 64 can be adjusted as desired by changing the relative angle around the axis.

Also, if the engine vibration is high frequency,
The amplitude is small and the orifice 64 may become clogged. However, since the orifice 54 has a large cross-sectional area, the liquid inside the orifice 54 causes liquid column resonance without causing clogging, thereby appropriately absorbing high frequency vibrations.

FIG. 3 shows the size of the loss factor with respect to frequency when using the vibration isolator according to this embodiment, and characteristic 70 is a low frequency large amplitude;
2 is the size of the loss factor at high frequency and small amplitude. Further, FIG. 4 shows the dynamic spring constant with respect to frequency when the vibration isolator of this embodiment is used. In FIG. 4, a characteristic 74 indicates a dynamic spring constant at low frequency and large amplitude, and a characteristic 76 indicates a dynamic spring constant at high frequency and low amplitude.

In FIGS. 3 and 4, characteristics 70 and 74 are achieved by orifice 64, characteristics 72 and 76 are achieved by orifice 54, and characteristic 78 shown by a broken line in FIG. 4 is achieved only by orifice 64. It shows the dynamic spring constant when provided.

In this way, this embodiment makes it possible to obtain a large loss factor even during high-frequency vibrations, dampen the vibrations, and improve the ride comfort of the automobile.

Although the above embodiment shows a structure in which the liquid chamber is divided into three small liquid chambers, the present invention can also be applied to a case having four or more small liquid chambers, and in this case also, the liquid chamber can be divided into three small liquid chambers. One of the restriction passages connecting the two may have a larger cross-sectional area than the other one, and may be placed closer to the vibration source than the other one.

[Effects of the Invention] As explained above, in the vibration isolating device according to the present invention, a hollow chamber is divided into three or more small liquid chambers arranged in series by a plurality of restriction passages each having an annular longitudinal axis. , one of the plurality of restriction passages has a larger cross-sectional area than the other one, and is placed closer to the vibration source than the other one, so low frequency large amplitude By using the restriction passage, it is possible to attenuate vibrations of small high-frequency waves with a large cross-sectional area, and by changing the size of the restriction passage, it is possible to attenuate vibrations of any frequency.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of the vibration isolator according to the present invention, FIG. 2 is an exploded perspective view showing an upper partition plate and an abutment plate, and FIG. Diagram showing the relationship with loss factors, 4th
The figure is a diagram showing the relationship between frequency and dynamic spring constant. 14...Lower diaphragm, 22...Rubber, 24
... Base plate, 32 ... Cylindrical diaphragm, 36 ...
Upper partition plate, 37A... Upper liquid chamber, 37B... Middle liquid chamber, 37C... Lower liquid chamber, 42... Contact plate, 50...
... Communication hole, 52 ... Communication hole, 54 ... Orifice, 56 ... Lower bulkhead plate, 62 ... Contact plate, 64 ...
...Orifice, 66...Communication hole, 68...Communication hole.

Claims (1)

[Claims] 1 A hollow chamber mainly made of a hollow molded body of an elastic material that mainly acts as a vibration absorber is used as a liquid chamber, and the hollow chamber is arranged in three or more series in series by a plurality of restriction passages whose longitudinal axes are annular. One of the plurality of restriction passages is defined as a restriction passage having a larger cross-sectional area than the other one, and is arranged closer to the vibration source than the other one. Anti-vibration device.