JPH07293634A - Vibration isolator - Google Patents

Abstract

PURPOSE:To provide vibration isolating performance excellent even for vibration having high frequency and small amplitude. CONSTITUTION:The lower side of a cylindrical rubber film 16 is fixed on a lower part attaching tool 10, and the upper side of the rubber film 16 is fixed on an upper part attaching tool 18. A main liquid chamber 30 in which a bulkhead is to be formed by the inner wall surfaces of the attaching tools 10, 18 and the rubber film 16 is provided. A first sub liquid chamber 56 communicated with the main liquid chamber 30 through a passage 26 is formed by recessed parts 32, 34 of metallic blocks 22, 24. A first sub liquid chamber 56 and an air chamber 60 is so formed as to pinch the diaphragm 42, and it is communicated with a pressurizing source 64. An annular groove 10B recessed into a ring shape is formed on the lower part attaching tool 10, and an elastic film body 14 is arranged so as to cover the annular groove 10B. One end side of a pipe 28 is connected to the bottom surface of the annular groove 10B, and the other end side of the pipe 28 is connected to the metallic block 22 so as to be connected to the recessed part 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping device for preventing the transmission of vibrations from a member that generates vibrations, and is applicable to, for example, a cab mount, a seat suspension, an air suspension and the like arranged in a vehicle. Is.

[0002]

2. Description of the Related Art For example, a vehicle is provided with an anti-vibration device as a cab mount between a vehicle body serving as a vibration generating portion and a cab serving as a vibration receiving portion. An air spring as a spring element and a shock absorber as a damping element incorporated in the vibration isolator absorb the oil and prevent it from being transmitted to the cab side.

Therefore, when the engine mounted on the vehicle body operates or the vehicle travels and vibration occurs on the vehicle body side, the air spring can provide a soft spring property and a shock absorber. The damping force of suppresses resonance and accelerates damping of vibration.

[0004]

However, in such a structure, when a vibration with a high frequency and a small amplitude is generated on the vehicle body side, the vibration is transmitted to the cab side via the shock absorber. Without fully utilizing the effect of the spring,
It has a drawback that the vibration damping effect is insufficient.

Here, this defect will be specifically described below by taking a cab mount for a truck as an example.

Vibration of a low amplitude (several Hz) and a large amplitude (amplitude of several mm) input from the vehicle body side while the truck is running is sufficient due to the soft spring property of the air spring and the damping force of the shock absorber. Controlled to realize extremely good vibration isolation performance.

However, high frequency (10
When a small amplitude vibration (Hz or more) is input from the vehicle body side of the truck, compared with the vibration transmission force transmitted via the air spring due to the vibration, the vibration transmission force transmitted via the shock absorber. Is about 20 times larger. That is,
With respect to such high frequency and small amplitude vibration, the damping force of the shock absorber has the opposite effect, and the effect of the air spring cannot be fully utilized, and the vibration damping effect is insufficient.

Therefore, at the time of idle vibration or the like, a sufficient vibration isolation effect cannot be obtained, and vibration is transmitted to the cab, which causes muffled noise in the cab or makes the riding comfort in the cab worse. It was a cause of such a bad effect.

In consideration of the above facts, an object of the present invention is to provide a vibration damping device which can obtain good vibration damping performance even at high frequency and with small amplitude vibration.

[0010]

According to a first aspect of the present invention, there is provided a vibration isolator having a first mounting member connected to one of a vibration generating portion and a vibration receiving portion and a vibration detecting portion and a vibration receiving portion connected to the other. A second mounting member, a cylindrical film body that connects the mounting members and is deformable with the displacement of the vibration generating part, and a liquid is enclosed with the film body as a part of the inner wall. And a main liquid chamber whose internal volume changes due to deformation of the film body,
A sub liquid chamber that is connected to the main liquid chamber via a passage and at least a part of the inner wall of which is a diaphragm that is expandable and contractible, and an air chamber that is arranged to face the sub liquid chamber with the diaphragm interposed therebetween. A gas supply / discharge means connected to the air chamber to change the air pressure in the air chamber, and interposed between the main liquid chamber and the sub liquid chamber, and with a change in the liquid pressure in the main liquid chamber. And an elastic film body that is deformed.

[0011]

The operation of the invention according to claim 1 will be described below.

The gas supply / exhaust means changes the atmospheric pressure in the air chamber which is arranged to face the sub-liquid chamber with the diaphragm interposed therebetween.
Keep the diaphragm deformable. When the diaphragm is deformable and vibration is transmitted from the vibration generator side connected to one of the mounting members, the inner volume of the main liquid chamber changes as the film body deforms. The liquid flows between the sub liquid chamber and the main liquid chamber, which communicate with the main liquid chamber via the passage.

Therefore, when a vibration with a low frequency and a large amplitude is transmitted from the vibration generating portion side, the diaphragm is deformed and the liquid flows between the main liquid chamber and the sub liquid chamber, so that the liquid in the passage of the liquid is flown. Resonance is suppressed by the damping accompanying the viscous resistance due to the flow.

On the other hand, since the elastic film body interposed between the main liquid chamber and the sub liquid chamber is deformed in accordance with the fluctuation of the liquid pressure in the main liquid chamber, a vibration of a high frequency and a small amplitude is generated. When transmitted from the side, the elastic film body is deformed so that the pressure increase of the liquid hardly occurs, and the liquid does not flow and is less likely to be attenuated. Then, the pressure fluctuation in the sub-liquid chamber due to the deformation of the elastic film body is absorbed by the deformation of the diaphragm. Therefore, the increase of the dynamic spring constant hardly occurs, and according to the vibration isolator of the present invention, effective vibration isolation performance can be obtained even for vibration of high frequency and small amplitude.

That is, an air spring is constituted by the air chamber, the gas supply / discharge means, the diaphragm and the like, and a shock absorber is constituted by the main liquid chamber, the sub liquid chamber and the passage. As a result, the elastic film body suppresses the damping by the shock absorber.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a vibration isolator according to the present invention is shown in FIGS. 1 to 3, and one embodiment will be described based on this drawing.

As shown in FIG. 1 which is a sectional view of the present embodiment, the lower side of the cylindrical lower mounting member 10 which is the first mounting member and constitutes the lower side of the vibration isolator 100 is A fitting cylinder portion 10A for fitting and fixing the vibration damping device 100 to the vehicle body 40 is formed.

On the outer peripheral surface on the upper side of the lower fixture 10, the lower side of the rubber film 16 (for example, a rolling diaphragm) having a tubular shape and having a reinforcing polyester or nylon cord embedded therein is a metal band. It is fixed by tightening with 19A. This rubber film 16
Hangs downward from this tightened portion to form a rolling portion 16A, and extends further upward. The upper side of the rubber film 16 is fixed to the outer peripheral surface of a disk-shaped upper mounting member 18 serving as a second mounting member by tightening with a metal band 19B. As described above, the rubber film 16 interposed between the lower fixture 10 and the upper fixture 18 and connected to each of them serves as a film body.

A hole 18A that closes the upper portion is provided in the central portion of the upper mounting member 18, and a cab (not shown) for passengers to board is connected to the upper portion of the upper mounting member 18. A screw hole 18B used for the purpose is provided.

Further, the lower mount 10 and the upper mount 18
A main liquid chamber 30 in which a partition wall is formed by the inner wall surfaces of the lower fixture 10, the upper fixture 18, and the rubber film 16 and the like.
Is provided, and a liquid such as antifreeze or oil is sealed in the main liquid chamber 30.

On the other hand, at different positions in the vehicle body 40 apart from the lower mount 10, the upper mount 18, the rubber film 16 and the like,
A pair of metal blocks 22, 24 whose outer circumferences are screwed with bolts 20 are installed. The metal block 2 located on the upper side of the pair of metal blocks 22 and 24
A concave portion 32 is formed on the lower surface side of No. 2 and a portion corresponding to the concave portion 32 is provided on the upper surface side of the metal block 24 located on the lower side and opposite to the concave portion 32 of the upper metal block 22. A concave portion 34 having a spherical shape is formed.

A rubber diaphragm 42 is located between the pair of recesses 32 and 34, with its outer peripheral portion sandwiched between the pair of metal blocks 22 and 24.
That is, the diaphragm 42 vertically divides the space formed by the recesses 32 and 34 into two parts. Further, a pipe 46 communicating with a pressure source 64, which is a gas supply / discharge means composed of a compressor or the like, is connected to the bottom of the recess 34.

The pressure source 64 is connected to the control means 68, and the operation thereof is controlled by the control means 68. The control means 68 is operated by the vehicle power source, receives the detection signals from at least the vehicle speed sensor and the engine speed detection sensor (not shown), detects the vehicle speed and the engine speed, and can determine whether the engine is idling or running. ing.

On the other hand, one end of a small-diameter pipe 26 is connected to the lower attachment 10 so as to penetrate the lower attachment 10, and the other end of the pipe 26 has a recess 32.
It is connected to the metal block 22 so as to be connected to.

As described above, the upper side of the space formed by the recesses 32 and 34 becomes the first sub-liquid chamber 56 which is communicated with the main liquid chamber 30 via the pipe 26 and in which the liquid is sealed, and the diaphragm of this space. The lower side across 42 is the air chamber 60
Becomes The pipe 26 constitutes a passage, and this passage serves as an orifice which has a large liquid passage resistance and is used in a traveling state of the vehicle.

Further, by applying an air pressure that balances the liquid pressure to the air chamber 60 from the pressurizing source 64, the diaphragm 42 can be deformed, and the diaphragm constituting at least a part of the inner wall of the first sub liquid chamber 56. 42 can be expanded and contracted.

Further, since the metal blocks 22 and 24 having the sub liquid chamber 56 are separated from the rubber film 16 and the like to have a separate structure, the length of the pipe 26 can be freely set and the vehicle body 40 can be set. It is possible to install the first sub liquid chamber 56 by utilizing an arbitrary space therein.

On the other hand, on the upper surface side of the lower fixture 10, an annular groove 10 which surrounds the connecting portion of the pipe 26 and is recessed in a ring shape.
B is formed, and a pair of support fittings 12A and 12B each having a ring shape and an L-shaped cross section are fitted and arranged on the inner and outer peripheral surfaces of the annular groove 10B. There is. Then, the pair of support fittings 1
The inner and outer peripheral sides of a ring-shaped elastic film body 14 made of rubber are attached to 2A and 12B by means such as vulcanization adhesion. Therefore, the elastic film body 14 is arranged so as to cover the annular groove 10B between the pair of support fittings 12A and 12B.

Further, one end of a pipe 28 having an inner diameter larger than the inner diameter of the pipe 26 is connected to the bottom surface of the annular groove 10B, and the other end of the pipe 28 is connected to the recess 32. Thus, it is connected to the metal block 22.

The ring-shaped space formed by the annular groove 10B and the elastic film body 14 serves as a second sub liquid chamber 58, and at least the inner wall of the second sub liquid chamber 58 is formed by the elastic film body 14. A part is configured, and the second sub liquid chamber 58 and the main liquid chamber 30 are located opposite to each other with the elastic film body 14 interposed therebetween.

Next, assembly of the cab to the vehicle body 40 will be described. When the cab to be supported is mounted on the upper part of the upper fixture 18, the liquid pressure in the main liquid chamber 30 increases due to the weight of the cab, and the liquid causes the orifice 52 to flow from the main liquid chamber 30 to the first sub liquid chamber 56. The rubber film 16 is deformed at a rolling portion 16A while flowing in through a certain amount. Then, the diaphragm 42 forming a part of the inner wall of the first sub liquid chamber 56 is inverted from the position shown in FIG. 1 and is crimped to the concave portion 34 formed in a spherical shape. Sub liquid chamber 5
It may be difficult to change the internal volume of 6.

However, after that, a gas that can withstand the liquid pressure is sent from the pressurizing source 64 to the air chamber 60 to pressurize the diaphragm 42 so that it can be expanded and contracted. It can be in a state when it acts on.

Next, the operation of this embodiment will be described. The pressure source 64 changes the atmospheric pressure in the air chamber 60, which is arranged so as to face the first sub liquid chamber 56 with the diaphragm 42 interposed therebetween, and maintains the diaphragm 42 in a deformable state. Therefore,
The air chamber 60, the diaphragm 42, and the rubber film 16 in which the liquid is sealed elastically support a heavy object such as a cab on the vehicle body 40.

An engine (not shown) mounted on the vehicle body 40 with the diaphragm 42 deformable.
When the vehicle is running or the vehicle is running and vibration is transmitted from the side of the vehicle body 40 connected to the lower mounting member 10, the lower mounting member 10 is displaced and the rubber film 16 is deformed, so that the main liquid The internal volume of the chamber 30 changes, and the liquid flows between the main liquid chamber 30 and the first sub-liquid chamber 56 that communicates with the main liquid chamber 30 via the pipe 26.

Therefore, when the vehicle is running and vibrations of low amplitude and large amplitude are transmitted from the vehicle body 40 side, the diaphragm 42 is deformed to cause a gap between the main liquid chamber 30 and the first sub liquid chamber 56. A characteristic of tan δ (shown in FIG. 3) is shown in which the liquid flows through the pipe 26 and the attenuation is maximized at a predetermined vibration frequency that is tuned in advance. Therefore, the resonance is suppressed by the attenuation caused by the viscous resistance and the like due to the flow of the liquid in the pipe 26.

On the other hand, the elastic film body 14 interposed between the main liquid chamber 30 and the first sub-liquid chamber 56 with the pipe 28 and the second sub-liquid chamber 58 interposed therebetween is the liquid in the main liquid chamber 30. It deforms with changes in pressure. Therefore, when the engine is idling, idle vibration, which is high-frequency and small-amplitude vibration, is generated and transmitted from the vehicle body 40 side. In this case, however, the elastic film body 14 is deformed and the inside of the main liquid chamber 30 is deformed. Almost no increase in the pressure of the liquid occurs, and the liquid does not flow and is less likely to decay.

Then, the first deformation caused by the deformation of the elastic film body 14
The pressure fluctuation in the sub liquid chamber 56 is absorbed by the deformation of the diaphragm 42. Therefore, as shown in FIG. 3, the dynamic spring constant Kd when the elastic film body 14 indicated by the chain double-dashed line does not exist.
The dynamic spring constant Kd indicated by the solid line hardly rises in comparison with the characteristics of No. 1, and the vibration damping device 100 of the present embodiment has effective vibration damping performance even for vibrations of high frequency and small amplitude. Will be obtained.

Even when a large-amplitude vibration at a low frequency is transmitted from the vehicle body 40 side, the elastic film body 14 is deformed, but it hits the bottom surface of the annular groove 10B and is suppressed from being deformed to a certain value or more. . Therefore, the main liquid chamber 30 and the first sub-liquid chamber 56
The liquid actively flows through the pipe 26 between and.

Further, for example, when the static load due to the weight of the cab changes, the height of the cab can be adjusted to a constant value by further increasing the atmospheric pressure of the gas applied to the air chamber 60.

Further, in the above-described embodiment, the lower mount 10 serving as the first mounting member is connected to the vehicle body 40 serving as the vibration generating unit, and the upper mounting serving as the second mounting member is mounted to the cab serving as the vibration receiving unit. Although the configuration is such that the tool 18 side is connected, the configuration may be reversed. Further, as the film body, a bellows type film body may be used instead of the rubber film 16 as in the embodiment, and may be replaced with another well-known structure.

Further, in the above embodiment, the elastic film body 1
The pipe 28 and the second sub-liquid chamber 58 were installed between the No. 4 and the first sub-liquid chamber 56.
The elastic film body 14 may be arranged so as to be a part of the partition wall of No. 6.

On the other hand, in the above-mentioned embodiment, the purpose is to prevent the vibration of the cab mounted on the vehicle, but it goes without saying that the vibration-proof device of the present invention can be used for other purposes.
The shape and the like are not limited to those of the embodiment.

[0043]

As a result of the structure described above, the vibration isolator of the present invention can obtain good vibration isolation performance even at high frequencies and with small amplitude vibration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a vibration isolation device according to the present invention.

FIG. 2 is a view taken along arrow 2-2 of FIG.

FIG. 3 is a diagram showing a graph showing a vibration isolation performance according to an embodiment of the vibration isolation device according to the present invention.

[Explanation of symbols]

 10 Lower Attachment (First Attachment) 14 Elastic Membrane 16 Rubber Membrane (Membrane) 18 Upper Attachment (Second Attachment) 26 Pipe (Passage) 30 Main Liquid Chamber 42 Diaphragm 56 First Sub-Liquid Chamber (sub liquid chamber) 60 Air chamber 64 Pressurizing source (gas supply / discharge means) 100 Vibration isolation device

Claims (1)

[Claims] 1. A first mounting member connected to one of the vibration generating unit and the vibration receiving unit, a second mounting member connected to the other of the vibration generating unit and the vibration receiving unit, and a space between these mounting members. A tubular film body that is connected and can be deformed with the displacement of the vibration generating part, and a liquid is enclosed with the film body as a part of an inner wall, and the internal volume is changed by the deformation of the film body. A main liquid chamber, a sub liquid chamber communicating with the main liquid chamber via a passage, and at least a part of an inner wall of which is configured to be expandable / contractible, and a sub liquid chamber facing the sub liquid chamber with the diaphragm interposed therebetween. An air chamber arranged, a gas supply / discharge means connected to the air chamber for changing the atmospheric pressure in the air chamber, a liquid interposed between the main liquid chamber and the sub liquid chamber and in the main liquid chamber And an elastic film body that deforms with a change in pressure, Anti-vibration apparatus according to symptoms.