JPH11101297A - Fluid-filled vibration control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid-filled vibration control device, having simple structure, to produce a vibration control effective to input vibration, having a plurality of frequency areas, by changing the tuning characteristics of a single orifice passage. SOLUTION: In this device, a part of the wall part of an auxiliary liquid chamber 70 communicated with a main liquid chamber 42 through an orifice passage 81 is formed of an elastic film 50 having an elastic restoration force, and a working air chamber 82 is formed at the back of the elastic film 50. An air pressure is exerted on the working air chamber 82 to elastically deform the elastic film 50. By maintaining a part thereof in a state to make contact with a constraint member 72, the spring characteristics of the elastic film 50 are hardened by maintaining a part thereof in a state to make contact with the constraint member 72, whereby wall spring rigidity of the auxiliary chamber 70 is increased. This constitution varies the tuning frequency of the orifice passage 81 to a high frequency area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid filled type vibration damping device using a vibration damping effect based on a flow action such as a resonance action of an incompressible fluid sealed therein, and more particularly to a vibration damping device using air pressure. The present invention relates to a fluid-filled type vibration damping device capable of changing a vibration frequency range in which a vibration damping effect based on a fluid flow action is exhibited by controlling characteristics.

[0002]

2. Description of the Related Art Conventionally, as a kind of a vibration isolating support or a vibration isolating connecting body such as an engine mount for an automobile, a first mounting member and a second mounting member which are separately arranged are connected by a rubber elastic body. On the other hand, a main liquid chamber in which a part of a wall is formed by the main rubber elastic body and a sub liquid chamber in which a part of the wall is formed of a movable film are formed independently of each other. 2. Description of the Related Art A fluid-filled type vibration damping device having a structure in which an incompressible fluid is sealed in a chamber and a sub-liquid chamber and an orifice passage communicating the main liquid chamber and the sub-liquid chamber with each other is provided. In such an anti-vibration device, an excellent anti-vibration effect, which is difficult to obtain by using only the rubber elastic body, is exhibited based on the resonance action of the fluid caused to flow through the orifice passage.

[0003] Since a plurality of types of vibrations having different frequencies are generally input to a vibration isolation device, an effective vibration isolation effect is required for the plurality of types of vibrations. For example, an engine mount for an automobile is required to have an anti-vibration effect against low-frequency vibration such as a shake and a high-frequency vibration such as a muffled sound during traveling, while requiring an anti-vibration effect against a medium-frequency vibration such as an idle vibration when the vehicle is stopped. The Rukoto. However, in the conventional fluid-filled type vibration damping device, the vibration damping effect exerted based on the resonance action of the fluid flowing through the orifice passage is limited only to the input vibration in the tuned limited frequency range of the orifice passage. It was not effective, and it was difficult to obtain a sufficient anti-vibration effect for a plurality of types of input vibration.

[0004] In order to deal with such a problem,
For example, by forming a plurality of orifice passages that are differently tuned from each other and selectively communicating them with each other by a valve body, a vibration damping effect based on a resonance action of a fluid that is caused to flow through each orifice passage can be selectively performed. There has been proposed a vibration isolator which can be used in such a case. However, in such a vibration isolator, the structure is complicated due to the assembly of the valve element, and it is inevitable that the production becomes difficult. In addition, since it is necessary to form a plurality of orifice passages independently of each other, in addition to being difficult to design, the flow passage cross-sectional area of each orifice passage is sufficiently secured, and it becomes difficult.
There is also a problem that the vibration damping effect based on the resonance action of the fluid is reduced.

[0005]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to change a tuning characteristic of one orifice passage with a simple structure. To provide a novel fluid-filled type vibration damping device capable of effectively exhibiting a vibration damping effect based on a resonance action of a fluid flowing through an orifice passage against a plurality of types of input vibrations. It is in.

[0006]

In order to solve such a problem, a feature of the present invention is that a first mounting member and a second mounting member which are separately arranged are connected by a main rubber elastic body. A main liquid chamber in which a part of a wall is formed by the main rubber elastic body and a sub liquid chamber in which a part of the wall is formed of a movable film are formed independently of each other; And an incompressible fluid sealed in the auxiliary liquid chamber and a first orifice passage communicating the main liquid chamber and the auxiliary liquid chamber with each other. Constructed of an elastic film having a restoring force, and on one side of the elastic film, a restraining member for restricting deformation of the elastic film is arranged, and on the opposite side to the main liquid chamber across the elastic film. A closed working air chamber is formed, and air pressure is applied to the working air chamber from outside to form the working air chamber. By elastically deforming the elastic film, a part of the elastic film is maintained in contact with the restraining member, so that the wall spring rigidity of the sub liquid chamber defined by the elastic film is increased. I did it.

In the fluid-filled type vibration damping device having the structure according to the present invention, the elastic membrane is not in contact with the restraining member, and the elastic membrane is in contact with the restraining member. By changing the spring characteristic of the elastic film, the rigidity of the wall spring of the sub liquid chamber defined by the elastic film is changed. The frequency range in which the vibration damping effect based on the resonance action of the fluid caused to flow through the orifice passage is exhibited is a ratio of the cross-sectional area of the orifice passage: A to the length of the passage: L: A / L, and the sealing. Since it is determined according to the specific gravity and viscosity of the fluid, the wall spring rigidity of the main liquid chamber and the sub liquid chamber, if the wall spring rigidity of the sub liquid chamber changes, the tuning of the orifice passage will change. As a result, the frequency range in which the vibration damping effect based on the resonance action of the fluid flowing through the orifice passage is changed.

Therefore, in such a fluid-filled type vibration damping device, the air pressure applied to the working air chamber is adjusted according to the input vibration, so that the elastic film is separated from the restraining member and the elastic film is restrained by the restraining member. By selectively expressing the state maintained in contact with the orifice, the tuning of the single orifice passage is changed, and thus, the vibration damping effect based on the resonance action of the fluid caused to flow through the orifice passage, All of them can be effectively exerted on input vibrations in different frequency ranges. In particular, in such a fluid-filled type vibration damping device, it is not necessary to mount a switching valve for the orifice passage, and a plurality of vibration damping characteristics can be exhibited by a single orifice passage. An anti-vibration device capable of exhibiting an effective anti-vibration effect with respect to a plurality of types of input vibrations while securing it can be advantageously realized.

The air pressure applied to the working air chamber is
Positive pressure or negative pressure may be applied, and the elastic membrane is deformed against its own elastic restoring force and has a pressure enough to maintain the contact state with the restraining member. Is fine. Also, in a state where the elastic film is separated from the restraining member, the working air chamber is preferably connected to the atmosphere, whereby a soft wall spring rigidity is realized in the sub liquid chamber. Further, as the elastic film, a film formed of a rubber elastic body is preferably used. In addition to a film made of a single material rubber elastic body, a laminate of a rubber elastic body of an appropriate material, a rubber elastic body, or the like. A composite of a resin layer, a canvas, a reinforcing material, and the like may be employed.

In order for the wall spring stiffness of the auxiliary liquid chamber to be advantageously increased by bringing the elastic membrane into contact with the restraining member, for example, the elastic membrane is pressed by air pressure applied to the working air chamber. By being elastically deformed,
The surface of the elastic member is partially and directly in close contact with the restraining member, and is brought into contact with the restricting member. The deformable area of the elastic film is reduced, so that the spring characteristic of the elastic film is hardened. A configuration in which the wall spring stiffness of the sub liquid chamber defined by the elastic film is increased can be suitably adopted.

The contact form of the elastic film with the restraining member may be any of a variety of forms in which a part of the elastic film is in contact with the elastic film, such as a peripheral portion or a central portion of the elastic film or a lattice portion. In addition, a plurality of discontinuous portions or a continuous specific portion of the elastic film can be brought into contact with the restricting member. Specifically, for example, in the elastic film, the center portion is made thicker than the outer peripheral portion to make the spring characteristics harder, and the elastic film is elastically deformed by the air pressure exerted on the working air chamber, so that the restraining member On the other hand, a configuration in which the outer peripheral portions are overlapped and brought into contact with each other is suitably adopted. If such a configuration is adopted, under a state where the elastic film is separated from the restraining member,
Due to the elastic deformation of the outer peripheral portion of the elastic film, a soft wall spring stiffness in the sub liquid chamber is developed, and in a state where the elastic film is kept in contact with the restraining member, the central portion of the elastic film causes Hard wall spring stiffness is exerted, and as a result, the tuning frequency of the orifice passage is effectively changed.

In order to advantageously increase the wall spring stiffness of the auxiliary liquid chamber by bringing the elastic film into contact with the restraining member, for example, the elastic film projects on the surface facing the restraining member. When the elastic film is elastically deformed by the air pressure exerted on the working air chamber, the distal end of the elastic protrusion is brought into contact with the restraining member, whereby the elastic film is formed. A configuration in which the spring characteristics are hardened so that the wall spring rigidity of the sub liquid chamber defined by the elastic film is increased can also be suitably adopted. The elastic projection does not need to be formed over the entire surface of the elastic film, and the specific shape of the elastic projection may be radial, scattered, spiral, lattice, or the like. As long as elastic deformation of the elastic film under the contact state can be substantially tolerated, various forms can be adopted in consideration of required spring characteristics.

Further, the shape of the elastic film is not particularly limited. For example, the thickness of the central portion is made thicker than that of the outer peripheral portion so that the spring characteristics are hardened, and the outer peripheral portion is formed of the working air chamber. An elastic film having a structure formed to have a tapered shape that protrudes in a tapered shape toward a side opposite to a side that is elastically deformed by air pressure exerted on the elastic film is preferably adopted. If such an elastic film is adopted, the elastic restoring force based on the elasticity of the elastic film itself when the air pressure is released is effectively exerted, and the set is also effectively reduced, so that good durability is obtained. Can be achieved.

In the present invention, preferably, when a part of the elastic film is maintained in a state of contact with the restraining member by air pressure applied to the working air chamber, the elastic film has a deformable portion. The air pressure in the working air chamber is exerted. Accordingly, a restraining force by air pressure is also exerted on the elastic film brought into contact with the restraining member, so that the wall spring rigidity of the sub liquid chamber can be more advantageously increased.

In the present invention, preferably, an equilibrium chamber in which a part of the wall is defined by a flexible film which is easily deformed is formed independently of the main liquid chamber and the sub liquid chamber. A second orifice passage communicating the balance chamber with the main liquid chamber is formed, and the second orifice passage is tuned to a lower frequency than the first orifice passage. When such a second orifice passage is formed, two different frequencies at which the vibration damping effect based on the resonance action of the fluid caused to flow through the first orifice passage is exhibited by changing the wall spring rigidity of the sub liquid chamber. In addition to the input vibration in the frequency range, an anti-vibration effect against the input vibration in another frequency range is exerted based on the resonance action of the fluid caused to flow through the second orifice passage. Therefore, an effective vibration damping effect can be obtained for input vibrations in a wider or three or more frequency ranges.

Further, in the present invention, for example, a first mounting member is arranged on one opening side of a cylindrical second mounting member, and the first mounting member and the second mounting member are arranged. One opening of the second mounting member is closed in a fluid-tight manner by the main rubber elastic body connecting the members, and the other opening of the second mounting member is closed in a fluid-tight manner by the flexible membrane. Thereby, a fluid chamber in which an incompressible fluid is sealed is defined between the main rubber elastic body and the flexible film, and the fluid chamber is fixedly supported by the second mounting member. By being divided into two by the partition member, a main liquid chamber and an equilibrium chamber are formed on both sides of the partition member,
Further, a space is formed inside the partition member, and the elastic film is accommodated and arranged in the space, and the space is fluid-tightly divided by the elastic film. A structure in which a liquid chamber and a working air chamber are formed, and an air supply / discharge hole for applying air pressure to the working air chamber from the outside is formed in the partition member is preferably employed.
By adopting such a structure, the main liquid chamber, the sub liquid chamber, the equilibrium chamber, and the working air chamber can be formed with a small number of parts and a simple structure with good space efficiency. In addition, by forming the second orifice passage on the outer peripheral portion of the partition member and forming the first orifice passage on the inner peripheral side thereof, the space for forming the two orifice passages, and hence the cross-sectional area and the length of the flow passage are reduced. The first and second orifice passages can be efficiently secured. In particular, by forming the first and second orifice passages so as to extend in the circumferential direction, the flow path length can be more advantageously and easily secured. Becomes

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, one embodiment of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows an engine mount 10 according to one embodiment of the present invention. The engine mount 10 includes a first mounting member 12 as a first mounting member and a second mounting member 14 as a second mounting member, which are opposed to each other with a predetermined distance therebetween. The first mounting bracket 12 is mounted on the power unit side and the second mounting bracket 14 is mounted on the body side, so that the power unit is vibration-isolated with respect to the body. It is designed to be supported. In the engine mount 10, the first mounting bracket 12 and the second mounting bracket 14 are substantially opposed to each other (see FIG. 1).
The power unit load and the vibration to be damped are input in the middle, substantially vertical direction, respectively, and the main rubber elastic body 16 is compressed and deformed by a predetermined amount by the power unit load. In the following description, the up-down direction refers to the up-down direction in FIG. 1 in principle.

More specifically, the first mounting member 12 has a substantially circular solid block shape extending in the up-down direction, and a plate-like stopper extending radially outward is provided at the axial middle portion. The part 18 is integrally formed. Further, the first mounting bracket 12 has a lower portion in the axial direction than the stopper portion 18,
While the holding portion 20 has an inverted truncated cone shape whose diameter gradually decreases downward, a bolt hole 22 extending in the axial direction is provided in a portion axially above the stopper portion 18. The first mounting bracket 12 is provided with the bolt holes 2.
2 is fixedly attached to a power unit (not shown) by an attachment bolt screwed to the power unit 2. The stopper portion 18 is provided with an annular buffer rubber 28 protruding upward in the axial direction. Through the buffer rubber 28, the stopper portion 18 is brought into contact with a body-side contact portion (not shown). , The relative displacement of the power unit with respect to the body is limited.

A rubber elastic body 16 is bonded to the first mounting member 12 by vulcanization. Body rubber elastic body 16
Has a large diameter substantially frustoconical shape as a whole, and is provided with a recess 24 which is open at the large diameter side end face. And
The holding portion 20 of the first mounting member 12 is vulcanized and bonded to the small-diameter end portion of the main rubber elastic body 16 while being inserted in the axial direction. A cylindrical connecting fitting 26 is vulcanized and bonded to the outer peripheral surface of the large-diameter end of the main rubber elastic body 16.

On the other hand, the second mounting member 14 has a large-diameter portion 32 on the upper side in the axial direction and a small-diameter portion 34 on the lower side in the axial direction, with the step portion 30 formed in the middle portion in the axial direction interposed therebetween. Has a stepped large diameter cylindrical shape, and is fixedly attached to the body side of the vehicle via a bracket (not shown). On the inner peripheral surfaces of the large-diameter portion 32 and the small-diameter portion 34, thin seal rubber layers 35 and 36 are provided over substantially the entire surface, respectively. An easily deformable thin-walled rubber diaphragm 38 as a flexible film, which is formed integrally with the layer 36, is provided. The opening on the small-diameter portion 34 side is closed in a fluid-tight manner by the diaphragm 38. .

The large-diameter portion 3 of the second mounting member 14 is
2 is externally inserted into the connection fitting 26 and the large-diameter portion 32 is subjected to drawing or the like, so that the large-diameter portion 32 is externally fixed to the connection fitting 26 in a fluid-tight manner. Thus, the first mounting member 12 and the second mounting member 14 are elastically connected by the main rubber elastic body 16. The opening of the second mounting member 14 on the large diameter portion 32 side is covered with the main rubber elastic body 16 in a fluid-tight manner, so that the main rubber elastic body 16 inside the second mounting bracket 14 is provided. A fluid chamber in which a predetermined incompressible fluid is sealed is formed between the opposed surfaces of the diaphragm and the diaphragm. In order to effectively obtain an anti-vibration effect based on the resonance action of the fluid, water or a low-viscosity fluid such as alkylene glycol, polyalkylene glycol, or silicone oil having a viscosity of 0.1 Pa · s or less is used as the sealed fluid. Adopted advantageously.

Furthermore, the small diameter portion 34 of the second mounting member 14
Is provided with a partition member 40 having a substantially circular block shape as a whole. And this partition member 40
As a result, the fluid chamber formed inside the second mounting member 14 is partitioned on both sides in the axial direction.
On the upper side in the axial direction of 0, a part of the wall is
The main liquid chamber 42 in which an internal pressure change is caused based on the elastic deformation of the main rubber elastic body 16 at the time of vibration input is formed. A part of the diaphragm 38 is formed, and an equilibrium chamber 44 in which a change in volume is easily allowed based on the deformation of the diaphragm 38 is formed.

Here, the partitioning member 40 has a substantially cylindrical bottomed outer wall member 48 provided with a central concave portion 46 opened at the center of the upper end surface in the axial direction. A rubber elastic film 50 as a movable film is accommodated and arranged at the bottom of the central recess 46, and a thick disk-shaped lid member 52 is fitted and fixed in the opening of the central recess 46, thereby opening the central recess 46. The portion is covered with a cover member 52. The partition member 40 is inserted into the second mounting member 14 from the large-diameter portion 32 side, and the outward flange portion 53 integrally formed on the opening side peripheral portion of the outer wall member 48 has the second direction. The small-diameter portion 34 of the second mounting member 14 is positioned on the second mounting member 14 by being superposed on the step portion 30 of the mounting member 14 and sandwiched between the main rubber elastic body 16. The outer peripheral surface of the partitioning member 40 is pressed against the inner peripheral surface of the small-diameter portion 34 with the seal rubber layer 36 interposed therebetween by performing drawing processing such as octagonal drawing and reducing the diameter. And is fixedly fitted.

The outer wall member 48 is formed with a concave groove 56 which is open to the outer peripheral surface and extends a predetermined length in the circumferential direction. The concave groove 56 is formed in the small diameter portion 34 of the second mounting member 14. The two ends are connected to the main liquid chamber 42 and the equilibrium chamber 44 through the communication holes 60 and 62, respectively, so that the two chambers 42 and 44 communicate with each other, and the internal pressure between the two chambers 42 and 44 is increased. A low-frequency side orifice passage 58 is formed as a second orifice passage that allows fluid flow between the two chambers 42 and 44 based on the difference. In the present embodiment, based on the resonance action of the fluid flowing through the low-frequency side orifice passage 58, an effective vibration damping effect against low-frequency vibration such as a shake of about 10 Hz is exerted. The length, cross-sectional area, and the like of the low-frequency side orifice passage 58 are set.

On the other hand, as shown in FIGS. 2 to 4, the rubber elastic film 50 housed and arranged in the partition member 40 is
It has a central portion 63 having a disk shape, and a tapered outer peripheral portion 64 extending obliquely downward from the outer peripheral edge of the central portion 63 in the axial direction. Further, the outer peripheral portion 64 is thinner than the central portion 63, so that elastic deformation is easily allowed. Furthermore,
The central portion 63 is integrally formed with eight elastic lips 63 protruding from the lower surface thereof and extending radially outward from the central portion, respectively. 63 has a hard spring characteristic. Further, an annular fitting ring 66 is fixed to the outer peripheral surface of the rubber elastic film 50 by vulcanization bonding or the like.

Further, the inner peripheral surface of the central concave portion 46 of the outer wall member 48 in which the rubber elastic film 50 is housed has an annular shape located at a middle portion in the depth direction and expanding radially inward from the outer peripheral surface. The stepped surface 72 is formed with a large-diameter concave portion 74 on the opening side of the stepped surface 72 and a small-diameter concave portion 76 on the bottom side of the stepped surface 72. Then, the fitting ring 6 adhered to the outer peripheral surface of the rubber elastic film 50.
6 is press-fitted into the central concave portion 46 of the outer wall member 48, and is fitted and fixed to the large-diameter concave portion 74 in a fluid-tight manner while being positioned and superimposed on the step surface 72, so that the large-diameter concave portion 74 At the bottom, it is arranged in a state of being spread in the direction perpendicular to the axis. Further, under such an arrangement state, the rubber elastic film 5
0 is located within the outer wall member 48 in a state where elastic deformation is allowed in both the central portion 63 and the outer peripheral portion 64 by being separated from the step surface 72 by a predetermined distance upward based on its own elasticity. It is located. As shown in FIG. 1, the step surface 72 of the central concave portion 46 is large enough to be axially opposed to the outer peripheral portion 64 of the rubber elastic film 50 over substantially the entirety thereof. The rubber elastic film 50 is formed so as not to face the central portion 63 of the rubber elastic film 50. In other words, the small-diameter concave portion 76 of the central concave portion 46 is formed to have substantially the same or slightly larger internal diameter as the central portion 63 of the rubber elastic film 50.

The opening of the central concave portion 46 of the outer wall member 48 in which the rubber elastic film 50 is accommodated and arranged is covered with the lid member 52 in a fluid-tight manner, so that the central concave portion 46 has
A sub-liquid chamber 70 in which the same incompressible fluid as the main liquid chamber 42 and the equilibrium chamber 44 is filled is formed between the rubber elastic film 50 and the facing surface of the lid member 52. The sub liquid chamber 70 is allowed to change in volume based on the elastic deformation of the rubber elastic film 50.

The cover member 52 has a circumferential groove 78 formed in the outer circumferential surface and extending in the circumferential direction.
By covering the outer wall member 48 with the peripheral wall portion 68 of the outer wall member 48, both ends are connected to the main liquid chamber 42 and the sub liquid chamber 70 through the communication holes 79 and 80, respectively, so that the two chambers 42 and 70 communicate with each other. A high-frequency side orifice passage 81 is formed as a first orifice passage that allows fluid flow between the two chambers 42 and 70 based on the internal pressure difference between the two chambers 42 and 70. In the present embodiment, the high frequency side orifice passage 81 is tuned to a higher frequency range than the low frequency side orifice passage 58, and based on the resonance action of the fluid caused to flow through the high frequency side orifice passage 81, Such a high frequency side orifice passage is provided so as to exhibit an effective vibration damping effect against vibrations in a high frequency region at which the vibration isolating effect of the low frequency side orifice passage 58 cannot be effectively exerted, such as idle vibration. The length, cross-sectional area, etc. of 81 are set.

On the other hand, in the bottom portion of the central concave portion 46, which is located on the opposite side of the sub liquid chamber 70 with the rubber elastic film 50 therebetween, the central concave portion 46 is fluid-tightly partitioned by the rubber elastic film 50. Thus, a working air chamber 82 is formed as an air chamber that is sealed from the external space. In the working air chamber 82, a step surface 72 is located.
The step surface 72 and the rubber elastic film 50 are opposed to each other with a space therebetween, and a part of the working air chamber 82 is also formed between the opposed surfaces. The outer wall member 48 is formed with an air supply / discharge passage 84 extending radially from the working air chamber 82 through the peripheral wall of the small-diameter concave portion 76, and the air supply / discharge passage 84 is formed in the second mounting member 14. Through the small diameter portion 34. Although not explicitly shown in the drawings, an air pipe 86 is fluid-tightly connected to the external opening of the air supply / discharge path 84 in a state where the engine mount 10 is mounted on the vehicle. The working air chamber 82 can be selectively connected to and communicated with the negative pressure source 90 and the atmosphere through a pipe 86 via a switching valve 88. In addition, as the negative pressure source 90, for example,
A negative pressure or the like generated in the intake system of the internal combustion engine can be advantageously used.

By switching the switching valve 88 while the engine mount 10 is mounted on the vehicle, the anti-vibration characteristics of the engine mount 10 can be switched.

That is, when the working air chamber 82 is connected to the atmosphere, the rubber elastic film 50 has a stepped surface 72 based on its own elastic force or the like as shown in FIG.
, And the whole of the central portion 63 and the outer peripheral portion 64 allows elastic deformation in a portion over the entire diameter: D. In particular, the outer peripheral portion 64
Is thinner than the central portion 63 and has a softer spring characteristic, so that the rubber elastic film 50 exhibits a softer spring characteristic as a whole. On the other hand, the working air chamber 8
2 is connected to a negative pressure source 90, and when a negative pressure is applied to the working air chamber 82, as shown in FIG. The elastic film 50 is deformed and displaced downward (toward the working air chamber 82) against its elastic force, and the lower surface of the outer peripheral portion 64 is continuously superimposed over the step surface 72 over the entire circumference. Be abutted. As a result, the outer peripheral portion 64 is
And the deformation is prevented, and only the central portion 63 allows the elastic deformation only in the portion having the diameter: D '. In particular, the central portion 63 is
Because the rubber elastic film 50 has a substantially smaller outer diameter as a whole, since the rubber elastic film 50 has a substantially smaller outer diameter, it has a harder spring characteristic. It is advantageously expressed. In short, by switching the connection between the working air chamber 82 to the atmosphere and the negative pressure source 90, the spring characteristic of the rubber elastic film 50 constituting a part of the wall of the sub liquid chamber 70 is changed between a soft state and a hard state. Can be switched. As is apparent from this, in the present embodiment, the stepped surface 72 constitutes a restricting member that restricts the deformation of the rubber elastic film 50.

On the other hand, the tuning frequency of the high frequency side orifice passage 81 (the vibration frequency range in which the vibration damping effect based on the resonance action of the fluid is effectively exerted) is the same as the cross-sectional area of the flow path of the high frequency side orifice passage 81: A Road length: ratio of L: A
/ L and the specific gravity and viscosity of the sealed fluid, as well as the wall spring rigidity of the main liquid chamber 42 and the sub liquid chamber 70. The wall spring rigidity of the main liquid chamber 42 and the sub liquid chamber 70 is
, The spring characteristic of the main liquid chamber 42 is mainly determined by the main rubber elastic body 16.
On the other hand, the wall spring stiffness of the sub liquid chamber 70 is exhibited mainly based on the spring characteristic of the rubber elastic film 50.

Accordingly, as described above, the connection between the working air chamber 82 in the atmosphere and the connection to the negative pressure source 90 is switched, and the spring characteristic of the rubber elastic film 50 is switched between a soft state and a hard state, whereby the auxiliary liquid chamber is changed. The rigidity of the wall spring 70 is switched between a soft state and a hard state, and the tuning frequency of the high frequency side orifice passage 81 is changed accordingly. Here, in particular, in the present embodiment, the spring characteristic of the rubber elastic film 50 is defined by the outer peripheral portion 64 restrained by the contact with the stepped surface 72 and the central portion 63 not restrained when the negative pressure acts on the working air chamber 82. Of the outer peripheral portion 6
The negative pressure suction force is also continuously exerted on the central portion 63 at the time of restraining by the step surface 72 of FIG. 4, so that the restraining force by the air spring action is exerted.
According to the switching of the connection to the atmosphere and the negative pressure source 90 for
The spring characteristics of the rubber elastic film 50 and, consequently, the wall spring stiffness of the sub liquid chamber 70 are greatly changed, so that the tuning frequency of the high frequency side orifice passage 81 is effectively changed.

Thus, in this embodiment, for example,
In the state shown in FIG. 1 in which the working air chamber 82 is connected to the atmosphere, the vibration is reduced to about 20 to 40 Hz by idle vibration or the like due to the vibration damping action based on the resonance action of the fluid flowing through the high frequency side orifice passage 81. An effective vibration damping effect against the corresponding medium-frequency vibration is exhibited, while the working air chamber 82 is connected to a negative pressure source. In the state shown in FIG. 5, the working air chamber 82 is caused to flow through the high-frequency side orifice passage 81. By vibration damping action based on resonance action of fluid,
An effective anti-vibration effect is exhibited against high-frequency vibration corresponding to muffled sound of about 50 to 80 Hz.

Therefore, in the engine mount 10 having the above-described structure, the high frequency side orifice passage 81 is provided.
By utilizing the above, it is possible to obtain an effective anti-vibration effect against input vibrations in a wide frequency range or a plurality of frequency ranges. In particular, there is no need to incorporate a complicated mechanism such as a switching valve inside, Since it is not necessary to form the orifice passage, it is possible to realize a control for changing the vibration isolation characteristics according to the input vibration with a simple and compact structure.

Further, the engine mount 10 of the present embodiment
In the above, the low frequency side orifice passage 58 is arranged in parallel, and the two orifice passages 58 and 81 effectively provide the vibration damping effect based on the resonance action of the fluid against the input vibration in substantially three frequency ranges. You can get
In addition, in the state where the working air chamber 82 is connected to the negative pressure source, the spring rigidity of the rubber elastic film 50 is increased, so that it is exerted based on the resonance action of the fluid caused to flow through the low frequency side orifice passage 58. Thus, the vibration-proof effect against low-frequency vibration is more advantageously exhibited.

As described above, one embodiment of the present invention has been described in detail, but this is a literal example.
It is not to be construed that the invention is limited only to such specific examples.

For example, in the above-described embodiment, the step surface 72 as a restraining member for partially restraining the rubber elastic film 50 by the action of the negative pressure is formed in an annular shape so as to face the outer peripheral portion 64 of the rubber elastic film 50. However, the constraining member may be any member that can restrict the deformation of a part of the rubber elastic film 50 and harden the spring characteristics. It is not limited at all.
In addition, the restraining member is moved with respect to the rubber elastic
The rubber elastic film 50 is partially constrained by applying a positive pressure to the working air chamber 82 to swell the rubber elastic film 50 toward the auxiliary liquid chamber 70 and abut against the restricting member. You may do it.

Further, in the above embodiment, the rubber elastic film 5
0 is brought into contact with the step surface 72 as a restraining member, whereby the outer diameter dimension is substantially reduced and the spring characteristics are hardened. In addition, the outer diameter dimension of the rubber elastic film 50 is changed. Without doing so, it is also possible to harden the spring characteristics of substantially the whole. Specifically, for example, as shown in FIG. 6, by forming the central concave portion 46 only by the large-diameter concave portion 74, the flat bottom surface 92 of the central concave portion 46 is placed below the rubber elastic film 50. The rubber elastic film 5 is positioned so as to face substantially the entire surface (the state shown by the phantom line in FIG. 6), and
The elastic elastic film 50 is elastically deformed so that the protruding distal end of the elastic lip 65 formed on the lower surface of the central portion 63 is kept in contact with the bottom surface 92 so that the rubber elastic film 50 is formed.
It is possible to harden the spring characteristics of substantially the whole without changing the outer diameter of the spring. That is, in such a state, the rubber elastic film 50 is
Because it is elastically supported by the elastic lip 65,
Due to the elastic deformation of the rubber elastic film 50 and the elastic lip 65,
In the rubber elastic film 50, a hard spring characteristic is advantageously exhibited.

The tuning of the low-frequency orifice passage 58 and the high-frequency orifice passage 81 can be appropriately changed according to the characteristics required for the vibration isolator, and is not limited at all. Specifically, for example, in the above embodiment, the low-frequency orifice passage 58 is tuned to idle vibration or the like, and the high-frequency orifice passage 81 is further tuned to a low-frequency muffled sound and a high-frequency muffled sound in a higher frequency range. Tuning is also possible.

Further, in the engine mount 10 in the above embodiment, the outer peripheral portion 64 of the rubber elastic film 50 has a substantially constant size that can keep the outer peripheral portion 64 of the rubber elastic film 50 in contact with the stepped surface 72 with respect to the working air chamber 82. Although the negative pressure is applied, the engine mount 10 can be protected by, for example, increasing or decreasing the negative pressure applied to the working air chamber 82 to vibrate the rubber elastic film 50 at an appropriate frequency. It is also possible to control the vibration characteristics. In particular,
For example, the engine mount 10 shown in the above embodiment
In this case, the negative pressure applied to the working air chamber 82 is increased or decreased within an appropriate range to maintain the state in which the outer peripheral portion 64 is in contact with the stepped surface 72 or the outer peripheral portion 64 is
2 while maintaining the state separated from the rubber elastic film 50,
Suction force due to negative pressure in working air chamber 82 and rubber elastic film 50
It is possible to reciprocate up and down (vibrate) up and down by the restoring force based on the elasticity of the rubber itself. By vibrating the rubber elastic film 50 in this manner, the internal pressure of the sub liquid chamber 70 can be controlled. . Therefore, at the time of vibration input, the rubber elastic film 50 is vibrated at a frequency corresponding to the input vibration to cause an internal pressure fluctuation in the sub liquid chamber 70, whereby the orifice passage between the sub liquid chamber 70 and the main liquid chamber 42 is formed. Fluid flow through 81 and 58 is positively generated, and a vibration damping effect using a fluid action such as a fluid resonance action or a vibration damping effect based on the internal pressure control of the main liquid chamber 42 is extremely effectively achieved. Will be demonstrated. The magnitude and phase of the air pressure exerted on the working air chamber 82 to vibrate the rubber elastic film 50 are determined by the main liquid chamber 4.
By controlling in accordance with the input vibration while taking into account the delay time of the pressure transmission to 2, the switching control of the mount anti-vibration characteristics can also be performed.

Further, in the above embodiment, the rubber elastic film 5
As 0, an approximately shallow bottom dish shape with a tapered outer peripheral portion 64 was adopted, but the shape is not limited at all. For example, a rubber elastic film having a generally flat plate shape is used. It is also possible to employ.

In the above-described embodiment, the equilibrium chamber 44 communicated with the main liquid chamber 42 through the low-frequency orifice passage 58 is provided. However, such a low-frequency orifice passage 58 and the equilibrium chamber 44 are provided. The anti-vibration device can also be configured without providing the device.

Further, in the above-described embodiment, a specific example is shown in which the present invention is applied to a vibration isolator having a structure in which the first mounting member and the second mounting member are opposed to each other in only one direction. In addition, according to the present invention, a first mounting member and a second mounting member are configured by a shaft member and an outer cylindrical member disposed at a predetermined distance radially outward of the shaft member. At the same time, the main rubber elastic body is interposed between the radially opposed surfaces of the shaft member and the cylindrical member, so that it is suitable as an engine mount, body mount, suspension bush, or the like for an FF type automobile, which is formed in a cylindrical shape as a whole. The present invention is also applicable to a fluid-filled type vibration damping device and the like used in the above.

In addition, in the above-described embodiment, a specific example in which the present invention is applied to an automobile engine mount is shown. However, the present invention is also applicable to an automobile body mount, a differential mount, and various devices other than automobiles. It goes without saying that any of them can be similarly applied to the anti-vibration device and the like.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, various changes, modifications, improvements, and the like can be made, and unless such embodiments depart from the spirit of the present invention.
Both are included in the scope of the present invention,
Needless to say.

[0048]

As is apparent from the above description, in the fluid-filled type vibration damping device having the structure according to the present invention, one orifice passage (the first orifice passage) can be operated only by switching the air pressure applied to the working air chamber. The tuning frequency of one orifice passage is changed to change the vibration damping effect exerted by the orifice passage. Therefore, a complicated mechanism such as a switching valve is incorporated in the apparatus, or a large number of orifices are used. Without having to provide a passage,
An anti-vibration device capable of exhibiting an effective anti-vibration effect against a plurality of types of vibrations can be advantageously realized with a simple and compact structure.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an engine mount as one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a rubber elastic film constituting the engine mount shown in FIG. 1, and is a view corresponding to a II-II cross section in FIG.

FIG. 3 is a bottom view of the rubber elastic film shown in FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is an explanatory longitudinal sectional view showing another operation state of the engine mount shown in FIG. 1;

FIG. 6 is an explanatory longitudinal sectional view showing a main part of an engine mount as another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 engine mount 12 first mounting bracket 14 second mounting bracket 16 main rubber elastic body 40 partition member 42 main liquid chamber 50 rubber elastic film 63 central part 64 outer peripheral part 70 sub liquid chamber 72 step surface 81 high frequency side orifice passage 82 Working air chamber 84 Air supply / discharge path

Claims (8)

[Claims] 1. A main liquid chamber in which a first mounting member and a second mounting member which are separately arranged are connected by a main rubber elastic body, and a part of a wall portion is constituted by the main rubber elastic body. The sub liquid chambers, each of which has a part of a wall formed of a movable membrane, are formed independently of each other, and the main liquid chamber and the sub liquid chamber are filled with an incompressible fluid, and the main liquid chamber and the sub liquid chamber are sealed. In a fluid-filled type vibration damping device provided with a first orifice passage communicating the sub liquid chambers with each other, the movable film is formed of an elastic film having elastic restoring force, and on one side of the elastic film, While a restraining member for restricting deformation of the elastic film is provided, a closed working air chamber is formed on the opposite side of the elastic film from the main liquid chamber, and an external air pressure is applied to the working air chamber. To cause the elastic film to elastically deform, so that a part of the elastic film Is maintained in abutment, the fluid filled type vibration damping device, characterized in that said defined by elastic membrane wall spring rigidity of the auxiliary liquid chamber is to be made to increase. 2. The elastic film is elastically deformed by the air pressure applied to the working air chamber, so that the surface thereof is partially overlapped with the restraining member and is brought into contact with the restraining member. 2. The fluid filling according to claim 1, wherein the deformable area of the elastic film is reduced, so that the spring characteristic of the elastic film is hardened, and the wall spring rigidity of the sub liquid chamber defined by the elastic film is increased. Type anti-vibration device. 3. The elastic film has a thicker portion at a central portion than an outer peripheral portion and has a high spring characteristic. The elastic film is elastically deformed by air pressure applied to the working air chamber, whereby the restraint is achieved. 3. The fluid filled type vibration damping device according to claim 2, wherein an outer peripheral portion of the member is overlapped and brought into contact with the member. 4. The elastic film has an elastic projection protruding on a surface facing the restraining member, and the elastic film is elastically deformed by air pressure applied to the working air chamber, and the elastic projection is formed. 2. The spring characteristic of the elastic film is hardened by contacting the distal end portion of the elastic member with the restraint member, and the wall spring rigidity of the sub liquid chamber defined by the elastic film is increased. The fluid filled type vibration damping device according to any one of claims 1 to 3. 5. The elastic film according to claim 1, wherein a thickness of a central portion is thicker than that of an outer peripheral portion so that a spring characteristic is hardened.
The fluid according to any one of claims 1 to 4, wherein the outer peripheral portion has a tapered shape that protrudes in a tapered shape toward a side opposite to a side that is elastically deformed by air pressure applied to the working air chamber. Enclosed vibration damping device. 6. An air pressure applied to the working air chamber keeps a part of the elastic film in contact with the restraining member, and applies a force to the deformable portion of the elastic film. The fluid filled type vibration damping device according to any one of claims 1 to 5, wherein air pressure of the chamber is applied. 7. An equilibrium chamber in which a part of a wall portion is defined by a flexible membrane which is easily deformed is formed independently of the main liquid chamber and the sub liquid chamber, and the equilibrium chamber is formed by the flexible chamber. The fluid according to any one of claims 1 to 6, wherein a second orifice passage communicating with the main liquid chamber is formed, and the second orifice passage is tuned to a lower frequency than the first orifice passage. Enclosed vibration damping device. 8. The method according to claim 8, wherein the first mounting member is disposed on one opening side of the cylindrical second mounting member, and connects the first mounting member and the second mounting member. One opening of the second mounting member is closed in a fluid-tight manner by the main rubber elastic body, and the other opening of the second mounting member is closed in a fluid-tight manner by the flexible film. Thereby, a fluid chamber filled with an incompressible fluid is defined between the main rubber elastic body and the flexible film,
By dividing the fluid chamber into two by a partition member fixedly supported by the second mounting member, the main liquid chamber and the equilibrium chamber are formed on both sides of the partition member. A void is formed inside the partition member,
The elastic film is housed and arranged in the space, and the space is fluid-tightly divided by the elastic film, whereby the auxiliary liquid chamber and the working air chamber are formed on both sides of the elastic film. 8. The fluid filled type vibration damping device according to claim 7, wherein an air supply / discharge hole for externally applying air pressure to the working air chamber is formed in the partition member.