JP2001041277A - Liquid-sealed type vibration control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably reduce the generation of vibration having low frequency high amplitude and vibration having high frequency low amplitude. SOLUTION: First - third liquid chambers 19-21 are situated between inner and outer cylinders 1 and 2. The first and second liquid chambers 19 and 20 are caused to intercommunicate through a first orifice 26 having a large equivalent mass and the first and third liquid chambers 19 and 21 are caused to intercommunicate through a second orifice 27 having a small equivalent mass. The two orifices 26 and 27 are formed along the inner peripheral surface of the outer cylinder 2. A rubber sheet 29 to close a space between the second and third liquid chambers 20 and 21 during input of vibration having amplitude exceeding a given value is provided on the chamber wall of the third liquid chamber 21. During input of vibration of low frequency high amplitude, a flow of liquid in the second orifice 27 is regulated by the rubber sheet 29 and only the first orifice 26 is operated. During input of vibration having high frequency low amplitude, the second orifice 27 is also operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolator used for a support portion of a vehicle engine and the like, and more particularly to a liquid filled type vibration isolator in which ethylene glycol, silicone oil or the like is sealed.

[0002]

2. Description of the Related Art A liquid-filled type vibration damping device of this kind is generally provided with a pair of elastically deformable liquid chambers and an orifice communicating these liquid chambers between an inner cylinder and an outer cylinder. The vibration is reduced by the resonance effect of the expanded elasticity of the orifice and the equivalent mass of the orifice.

However, in the case of an engine mount or the like, vibration reduction characteristics with respect to low-frequency, large-amplitude vibration such as an engine shake (vibration frequency range around 10 Hz) and idle vibration (vibration frequency range around 20 to 30 Hz). In some cases, vibration reduction characteristics with respect to high-frequency, small-amplitude vibrations are required. In such a case, the above-mentioned vibration damping device cannot sufficiently cope with such vibrations.

Therefore, conventionally, a liquid-filled type vibration damping device as shown in FIG. 11 has been developed to cope with this.

The liquid-filled type vibration damping device comprises a first liquid chamber 3 elastically deformed between the inner cylinder 1 and the outer cylinder 2 with the relative displacement between the inner cylinder 1 and the outer cylinder 2. First orifice 4 having a large equivalent mass (small cross section and long length) in liquid chamber 3
A second liquid chamber 5 communicating with the first liquid chamber 3 and a third liquid chamber 7 communicating with the same first liquid chamber 3 through a second orifice 6 having a small equivalent mass (a large cross-sectional area and a short overall length). The orifice (the first orifice 4) that resonates when a large-frequency vibration is input and when a high-frequency small amplitude vibration is input.
And the second orifice 6). That is, the chamber wall (diaphragm) constituting the third liquid chamber 7
8 is set to have a greater elasticity (thickness) than a chamber wall (diaphragm) 9 constituting the second liquid chamber 5, and when the vibration of low frequency and large amplitude is input, the first liquid chamber 3 and the chamber wall The liquid flows between the second liquid chamber 5 having a small elasticity 9 and the passage resistance of the first liquid chamber 3 and the orifice (the second orifice 6) communicating therewith when vibration of high frequency and small amplitude is input. The liquid flows between the third liquid chamber 7 and the small liquid chamber 7.

Incidentally, this similar technique is disclosed in, for example,
No. 7341 and the like.

[0007]

By the way, it is effective to reduce the vibration for a low-frequency, large-amplitude vibration, and to reduce the dynamic spring constant for a high-frequency, small-amplitude vibration. Is known to be effective. For this reason, even in the liquid-filled type vibration damping device, it is necessary to increase the loss factor in the low frequency vibration region and decrease the dynamic spring constant in the high frequency vibration region in order to improve the vibration reduction characteristics. But,
In the case of the liquid-filled type vibration damping device, if the equivalent mass of the first orifice 4 and the elasticity of the chamber wall 8 of the third liquid chamber 7 are increased in order to increase the loss factor in the low-frequency vibration region, dynamic vibration in the high-frequency vibration region is If the elasticity of the chamber wall 8 of the third liquid chamber 7 is reduced to reduce the dynamic spring constant in the high-frequency vibration region, the loss factor in the low-frequency vibration region is reduced. There is a defect.

Accordingly, an object of the present invention is to provide a liquid-filled type vibration damping device which can reliably reduce both low-frequency, large-amplitude vibration and high-frequency, small-amplitude vibration.

[0009]

According to the present invention, there is provided a liquid-filled type vibration damping device for reducing two kinds of vibrations having different amplitudes.
A first liquid chamber elastically deformed with the relative displacement of the inner cylinder and the outer cylinder, a second liquid chamber communicating with the first liquid chamber through a first orifice having a large equivalent mass, and an equivalent mass A third liquid chamber that communicates with a second orifice having a smaller diameter, both the first orifice and the second orifice along the inner peripheral surface of the outer cylinder, and the first liquid chamber and the second,
The third liquid chamber is formed so as to be connected in parallel with each other, and the third liquid chamber, or one end of the second orifice,
A movable plate for restricting the flow of the liquid in the second orifice at the time of vibration of a predetermined amplitude or more is provided.

[0010]

When the vibration of the low frequency and large amplitude is input, the movable plate regulates the flow of the liquid in the second orifice, so that the liquid flows mainly between the first liquid chamber and the second liquid chamber. The vibration is reduced by the resonance effect of the expansion elasticity of the liquid chamber and the equivalent mass of the first orifice. During the input of high-frequency small-amplitude vibration, the movable plate does not restrict the flow of the liquid in the second orifice, so that the liquid flows between the first liquid chamber and the second and third liquid chambers. Is reduced by the resonance effect of the expansion elasticity of the liquid chamber and the equivalent mass of the first and second orifices.

[0011]

Next, an embodiment of the present invention will be described with reference to FIGS. It is to be noted that the same parts as those of the conventional one shown in FIG.

First, a first embodiment will be described.

1 to 3, reference numeral 1 denotes an inner cylinder mounted on the vehicle body via a rod (not shown), and reference numeral 2 denotes an outer cylinder mounted on the engine via a bracket (not shown). The outer cylinder 2 has a pair of openings formed at an upper portion, and a thin (thin elastic) diaphragm 1 is formed therein.
0a and 10b are additionally provided. A metal tube 12 having a window 11 on the upper side is fitted and fixed to the inner peripheral side of the outer cylinder 2, and a rubber elastic body 13 is interposed between the metal tube 12 and the inner cylinder 1. . The rubber elastic body 13 extends upward so as to cover both end surfaces of the outer cylinder 12, and has a liquid sealing portion 14 above the outer cylinder 2 together with the diaphragms 10 a and 10 b.
Is formed, and a cavity 16 is formed in the lower part thereof to allow relative displacement of the inner cylinder 1 and the outer cylinder 2 in the radial direction.

A first partition plate 17 for vertically partitioning the liquid sealing portion 14 is fitted into the concave portion 15 of the rubber elastic body 13. A second partition plate 18 having a substantially U-shaped cross section for vertically partitioning a space above the partition plate 17 is fixed. In the liquid filling part 14,
The first partition plate 17 and the second partition plate 18 partition the liquid into three liquid chambers. The lower side of the first partition plate 17 is the first liquid chamber 19, the upper side of the second partition plate 18 is the second liquid chamber 20, A third liquid chamber 21 is provided between the first partition plate 17 and the second partition plate 18. Both ends of the first partition plate 17 extending in the tangential direction of the rubber elastic body 13 (the left-right direction in FIG. 1)
1 is joined to the inner peripheral surface of the outer cylinder 2, and an opening 22 facing the second liquid chamber 20 is provided at a portion near one end of the outer cylinder 2.
And an opening 23 facing the third liquid chamber 21. still,
The first liquid chamber 19 includes a rubber elastic body 13 whose center side is connected to the inner cylinder 1 and a first partition plate 17 whose both ends are joined to the outer cylinder 2.
And the inner wall 1 and the outer cylinder 2
Is relatively displaced in the radial direction, the chamber wall (the rubber elastic body 13) elastically deforms with the displacement.

Further, a groove 24 having a predetermined width which is continuous with the window 11 is formed on the outer peripheral surface of the cylindrical metal 12, and a semi-cylindrical member 25 is fitted in the groove 24. The semi-cylindrical member 25 has a first orifice 26 formed on its outer peripheral surface side, having a small cross-sectional area and meandering along the peripheral surface (formed so as to increase the equivalent mass). A second orifice 27 having a large area and formed linearly along the peripheral surface (formed so as to reduce the equivalent mass) is provided. One end of the first orifice 26 and the second orifice 27 both communicate with the first liquid chamber 19, and the other ends of the second orifice 27 and the second liquid chamber 20 communicate with each other through the openings 22 and 23 of the first partition plate 17. 21. Therefore, the first liquid chamber 19 and the second liquid chamber 20 communicate with each other through the first orifice 26 having a large equivalent mass.
And the third liquid chamber 21 have a second orifice 27 having a small equivalent mass.
Through.

On the other hand, a fluctuation regulating plate 28 having a substantially U-shaped cross section is attached to the second partition plate 18.
A rubber plate 29 as a movable plate is accommodated in the space defined by the second partition plate 18 and the fluctuation regulating plate 28 with a predetermined fluctuation margin d in the vertical direction. Through holes 30 and 31 are formed at positions of the fluctuation regulating plate 28 and the second partition plate 18 facing the rubber plate 29, respectively, and the upper and lower surfaces of the rubber plate 29 are passed through the through holes 30 and 31. Room 20
And the liquid pressure of the third liquid chamber 21 respectively acts. Here, the first liquid chamber 19 and the second and third liquid chambers 20, 21
The first orifice 26 and the second orifice 27 which communicate with the first and second orifices 27, respectively, have different cross-sectional areas and total lengths, so that the first liquid chamber 19 is elastically deformed with the relative displacement between the inner cylinder 1 and the outer cylinder 2. Then, each time, the second liquid chamber 20 and the third liquid chamber 2
There is a pressure difference between one. For this reason, the rubber plate 29 moves up and down with the elastic deformation of the first liquid chamber 19. In addition, the variation d of the rubber plate 29 is determined when the amplitude of the input vibration is equal to or greater than a predetermined amplitude (or greater than the amplitude during idle vibration).
9 is set so as to come into contact with the fluctuation regulating plate 28 and the second partition plate 18 during the fluctuation, and the rubber plate 29 is connected to the second liquid chamber 20 through the through holes 30 and 31 while the amplitude of the input vibration is small. When the flow of the liquid between the three liquid chambers 21 is allowed and the amplitude of the input vibration becomes larger than a predetermined amplitude, the rubber plate 29 substantially closes the gap between the second liquid chamber 20 and the third liquid chamber 21. Therefore, the flow of the liquid in the second orifice 27 is regulated by the rubber plate 29 when the input vibration is equal to or more than the predetermined amplitude.

Since the liquid-filled type vibration damping device is configured as described above, low-frequency large-amplitude vibration such as engine shake and high-frequency small-amplitude vibration such as idle vibration are reduced as follows. .

That is, when low-frequency, large-amplitude vibration is input, the rubber plate 29 regulates the flow of the liquid in the second orifice 27. The vibration mainly occurs between the first liquid chamber 19 and the third liquid chamber 20, and the vibration is caused by the expansion elasticity of the chamber walls of the first liquid chamber 19 and the second liquid chamber 20 and the equivalent mass of the first orifice 26. It is reduced by action. At this time, since the equivalent mass of the first orifice 26 is set to be large, the vibration is reliably reduced with a large loss factor.

When a high-frequency small-amplitude vibration is input to the outer cylinder 2, the rubber plate 29 is moved up and down within a range allowing the flow of the liquid between the second liquid chamber 20 and the third liquid chamber 21. Therefore, the flow of the liquid accompanying the elastic deformation of the first liquid chamber 19 occurs between the first liquid chamber 19 and the second and third liquid chambers 20 and 21 through the first orifice 26 and the second orifice 27. ,
The vibration is reduced by the resonance effect of the expanded elasticity of the chamber walls of the first liquid chamber 19 and the second liquid chamber 20 and the combined equivalent mass of the first and second orifices 26 and 27. At this time,
Diaphragms 10a, 1 constituting the chamber wall of the second liquid chamber 20
Since the elasticity of Ob is set to be small, the vibration is reliably reduced with a small dynamic spring constant.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the following, the same portions as those of the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description of the overlapping portions will be omitted.

This liquid filled type vibration damping device differs from that shown in the first embodiment only in the structure of the second partition plate 18 portion.
Other parts have the same structure. That is, the second partition plate 1
8, a window 32 is formed substantially in the center.
, A rubber elastic body 34 as a movable plate is attached via a retainer plate 33. This rubber elastic body 34
Has a substantially spherical shape that gradually increases in thickness toward the center, and is easily deformed by a thin portion at a peripheral portion thereof, and can be slightly changed in the vertical direction. In the case of the rubber elastic body 34, the second partition plate 18 and the retainer plate 33 allow the vertical margin d ′.
Is regulated.

In this liquid filled type vibration damping device, the space between the second liquid chamber 20 and the third liquid chamber 21 is always closed by the rubber elastic body 34. However, when the amplitude of the input vibration is small, Due to the fluctuation of the rubber elastic body 34 corresponding to the amplitude, the same pressure transmission as the liquid flow between the second liquid chamber 20 and the third liquid chamber 21 occurs, and the liquid can flow in the second orifice 27. become. When the amplitude of the input vibration is large, the fluctuation of the rubber elastic body 34 is regulated by the second partition plate 18 and the retainer 33, so that the flow of the liquid in the second orifice 27 is regulated.

Therefore, when low-frequency, large-amplitude vibration is inputted, the resonance effect of the expanded elasticity of the chamber walls of the first liquid chamber 19 and the second liquid chamber 20 and the equivalent mass of the first orifice 26 causes When the vibration is reduced and vibration of high frequency and small amplitude is input, the expanded elasticity of the chamber walls of the first and second liquid chambers 19 and 20 and the combined equivalent of the first and second orifices 26 and 27 are combined. Vibration is reduced by the resonance effect of the mass. Also at this time, the vibration of low frequency and large amplitude has a large loss factor, and the vibration of high frequency and small amplitude can be reliably reduced with a small dynamic spring constant.

The liquid-filled type vibration damping device of this embodiment differs from that of the first embodiment in that when the rubber elastic body 34 moves up and down, an elastic action of its peripheral portion acts. However, there is also an advantage that vibration noise or the like is less likely to occur when abutment against the second partition plate 18 or the retainer plate 33.

Next, a third embodiment of the present invention will be described with reference to FIG.

In this liquid-filled type vibration damping device, a rubber elastic body 36 is interposed between a tube 35 fitted to the outer tube 2 and the inner tube 1, and a tube metal is provided above the inner tube 1. 35 and the concave portion 37 of the rubber elastic body 36 form the first liquid chamber 19, and the second liquid chamber 19 is formed below the inner cylinder 1 by the cylinder metal 35 and the diaphragms 38 and 39 having small elasticity attached to the cylinder metal 35. A liquid chamber 20 and a third liquid chamber 21 are formed. And the first liquid chamber 1
9 and the second liquid chamber 20, and the first liquid chamber 19 and the third liquid chamber 21 are respectively provided on the outer peripheral side of the cylindrical metal 35 with a first orifice 26 having a large equivalent mass and a second orifice 27 having a small equivalent mass.
And communicate with each other. The diaphragms 38, 39
Is provided facing the cavity 16 formed in the rubber elastic body 36.

The third liquid chamber 21 of the second orifice 27
A rubber plate 29 as a movable plate similar to that used in the first embodiment is provided at the end facing the side, and this rubber plate 29 fluctuates substantially in the vertical direction due to a differential pressure between before and after the movable plate. It is supposed to. In this vibration isolator, the second liquid chamber 20 and the third liquid chamber 21 are elastically deformed independently by the diaphragms 38 and 39, respectively. It fluctuates with the fluctuation of the liquid pressure between the liquid chambers 21. Then, the rubber plate 29 is moved by the cylindrical metal 35 and the retainer plate 33 in a substantially vertical variation d.
Is regulated, whereby the flow of the liquid in the second orifice 27 when the amplitude of the input vibration is equal to or more than the predetermined amplitude is regulated.

In the above configuration, when vibration of low frequency and large amplitude is input to the outer cylinder 2, the flow of the liquid in the second orifice 27 is restricted by the rubber plate 29 and mainly the first liquid chamber 19 and the second The liquid flows between the liquid chambers 20, and the vibration is reduced by the resonance effect of the expanded elasticity of the chamber walls of the first liquid 19 and the second liquid chamber 20, and the equivalent mass of the first orifice 26. At this time, since the equivalent mass of the first orifice 26 is large, the vibration is reduced with a large loss factor. When high-frequency, small-amplitude vibration is input, the flow of the liquid in the second orifice 27 is not restricted by the rubber plate 29, so that the flow of the liquid flows through the first and second orifices 26 and 27, respectively. And the second liquid chamber 20, the first liquid chamber 19
Between the first and third liquid chambers 21 and the vibration is generated between the liquid chambers 19 and 2.
The expansion elasticity of the chamber walls 0, 21 and the first and second orifices 2
It is reduced by the resonance effect due to the combined equivalent mass of 6, 27. At this time, since the diaphragm 39 of the third liquid chamber 21 is set to have a small elasticity, the vibration is reliably reduced with a small dynamic spring constant.

Also, in the case of this vibration isolator, unlike the first and second embodiments, the second liquid chamber 20 and the third liquid chamber 21 are different from each other.
Can be independently elastically deformed by the diaphragms 38 and 39. In addition to the above-described basic effects, the dynamic spring constant at the time of inputting vibration of low frequency and large amplitude, There is an advantage that it is possible to separately set the dynamic spring constants at the time of inputting high-frequency small-amplitude vibration.

FIG. 8 shows a fourth embodiment of the present invention. In this liquid filled type vibration damping device, a rubber plate 29 as a movable plate is provided on the side of the first liquid chamber 19 of the second orifice 27. Only the point provided at the end is different from that of the third embodiment. Although this vibration isolator differs from that of the third embodiment in the place where the rubber plate 29 is provided, it works in the same manner for low-frequency, large-amplitude input vibration and high-frequency, small-amplitude input vibration.

In the third and fourth embodiments, the second liquid chamber 20 and the third liquid chamber 21 do not necessarily have to be elastically deformed independently. May be communicated.

FIGS. 9 and 10 show the loss factor-vibration frequency characteristic and the dynamic spring constant-vibration frequency characteristic of the vibration isolator according to the present invention and the conventional vibration isolator, respectively. The characteristics of the vibration isolator are indicated by solid lines, and the characteristics of the conventional vibration isolator are indicated by broken lines.) As is clear from these figures, the vibration isolator according to the present invention has a large loss factor in a low-frequency vibration range (around a frequency of 10 Hz) and a small dynamic spring constant in a high-frequency vibration range (around a frequency of 30 Hz). Become.

Here, the rapid increase of the loss factor in the low frequency range is caused by the first orifice 2 caused by a large amplitude vibration input.
6. The drop in the dynamic spring constant in the high frequency range is caused by the combined equivalent mass of the first orifice 26 and the second orifice 27 due to the small amplitude vibration input. Although caused by the resonance of the vibration system, the vibration isolator according to the present invention is:
Since the first orifice 26 is formed along the inner peripheral surface of the outer cylinder 2 having a sufficient circumferential length and width, the length is ensured to be sufficiently long so that the peak of the loss factor at the time of large amplitude vibration input can be further improved. Can be larger. And the second orifice 27
Is also formed along the inner peripheral surface of the outer cylinder 2, so that the width is wide and the length is sufficiently long to further reduce the drop of the dynamic spring constant when a small amplitude vibration is input. I can do it. In addition to this, the first orifice 26 and the second orifice 27 are formed by the first liquid chamber 19 and the second and third liquid chambers 2.
Since 0 and 21 are connected in parallel, when a small amplitude vibration is input, a sufficient width is secured by the two orifices 26 and 27 so that the dynamic spring constant in the intended frequency range can be further reduced.

[0034]

As described above, the present invention provides a first liquid chamber between an inner cylinder and an outer cylinder which is elastically deformed in accordance with the relative displacement between the inner cylinder and the outer cylinder, and is equivalent to the first liquid chamber. A second liquid chamber communicating with the first orifice having a large mass, and a third liquid chamber communicating with the second liquid orifice having a small equivalent mass in the first liquid chamber, both the first orifice and the second orifice,
The first liquid chamber and the second and third liquid chambers are formed along the inner peripheral surface of the outer cylinder so as to be connected in parallel with each other, and the third liquid chamber or the second orifice is formed. On one side,
A movable plate that regulates the flow of the liquid in the second orifice at the time of vibration of a predetermined amplitude or more is provided. Since two orifices with different equivalent masses can be selectively used when inputting vibration, a large loss factor is used for low-frequency, large-amplitude vibrations, and a small dynamic spring constant is used for high-frequency, small-amplitude vibrations. Can be reduced.

In particular, according to the present invention, both the first orifice and the second orifice for connecting the first liquid chamber and the second and third liquid chambers in parallel, respectively, are formed of an outer cylinder having a sufficient circumference and width. Since it is formed along the inner peripheral surface, the first orifice is set to a sufficient length so that a low frequency (10
(Frequency around Hz) Large amplitude vibration can be reliably reduced with a large loss factor peak, and the second orifice is made thick and long enough to reduce vibration like idle vibration. High-frequency (frequency around 20 to 30 Hz) small-amplitude vibration can be reliably reduced with a smaller dynamic spring constant.

In the present invention, the first liquid chamber is connected in parallel to the second and third liquid chambers via the first and second orifices, respectively. When a high-frequency small-amplitude vibration that does not restrict the flow of the liquid in the orifice is input, the liquid flows between the first liquid chamber and the second and third liquid chambers. As a result, the diameter of the first and second orifices is increased. Can be ensured and the orifice length can be increased without deviating from the target resonance frequency range, and the dynamic spring constant in that frequency range can be sufficiently reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a partially broken side view as viewed in the direction of arrow A in FIG. 1;

FIG. 3 is a plan view as viewed in the direction of arrow B in FIG. 1;

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a sectional view taken along the line CC of FIG. 4;

FIG. 6 is a plan view as seen in the direction of arrow D in FIG. 4;

FIG. 7 is a sectional view showing a third embodiment of the present invention.

FIG. 8 is a sectional view showing a fourth embodiment of the present invention.

FIG. 9 is a graph showing a loss factor-vibration frequency characteristic of the vibration isolator of the present invention and a conventional vibration isolator.

FIG. 10 is a graph showing dynamic spring constant-vibration frequency characteristics of the vibration isolator of the present invention and a conventional vibration isolator.

FIG. 11 is a sectional view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner cylinder 2 ... Outer cylinder 19 ... First liquid chamber 20 ... Second liquid chamber 21 ... Third liquid chamber 26 ... First orifice 27 ... Second orifice 29 ... Rubber plate (movable plate) 34 ... Rubber elastic body ( Movable plate)

Claims (1)

[Claims] In a liquid filled type vibration damping device for reducing two kinds of vibrations having different amplitudes, a first liquid elastically deformed between an inner cylinder and an outer cylinder with a relative displacement between the inner cylinder and the outer cylinder. Chamber, a second liquid chamber communicating with the first liquid chamber through a first orifice having a large equivalent mass, and a third liquid chamber communicating with the first liquid chamber through a second orifice having a small equivalent mass. Both the one orifice and the second orifice are formed along the inner peripheral surface of the outer cylinder, and are formed so as to connect the first liquid chamber and the second and third liquid chambers respectively in parallel. A liquid-sealed vibration isolator, wherein a movable plate is provided at one end of the third liquid chamber or at one end of the second orifice to restrict the flow of liquid in the second orifice when the vibration has a predetermined amplitude or more.