JP2672270B2 - Anti-vibration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration device for use in vehicles, general industrial machines and the like, which absorbs and damps vibrations from a vibration generator.

[0002]

2. Description of the Related Art A vibration isolator as an engine mount is arranged between an engine of an automobile and a vehicle body to prevent the vibration of the engine from being transmitted to the vehicle body.

Vibrations generated in the engine include so-called shake vibrations that occur when the vehicle is traveling at high speed,
There are so-called idle vibrations that occur during idling and when the vehicle is traveling at about 5 km / h.

Generally, the frequency of the shake vibration is 1
The frequency of idle vibration is 2 while it is less than 5 Hz.
The frequency is 0 to 50 Hz, and the shake vibration and the idle vibration have different frequencies.

A liquid-filled type vibration damping device has been proposed as a vibration damping device for absorbing the shake vibration and the idle vibration. As this vibration isolation device, for example, a vibration isolation device has been proposed which can change the characteristics of the vibration isolation device by utilizing negative suction pressure generated in the intake system of the engine.

[0006]

By the way, when the engine is started, the idling speed is increased to 900 to 1200 rpm, which is higher than the idling speed of about 700 rpm shown in FIG. The vibration frequency may be higher than the idle frequency of. For this reason, even if the anti-vibration device is tuned in advance for idle vibration, the dynamic spring constant K rises and vibration of the liquid in the anti-resonance region is generated at engine start-up, which is less than the idle speed. Until, the vibration will worsen.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an anti-vibration device capable of varying anti-vibration characteristics in order to solve the above-mentioned drawbacks in consideration of the above facts.

[0008]

According to a first aspect of the present invention, there is provided a vibration isolating device comprising:
A mounting member, a second mounting member connected to the other of the vibration generating unit and the vibration receiving unit, the first mounting member and the second mounting member.
An elastic body that is provided between the mounting member and the mounting member and that is deformed when vibration occurs, a main liquid chamber that is expandable and contractible by using the elastic body as a part of a partition wall, and a liquid is sealed therein; A first auxiliary liquid chamber that is in communication through the restriction passage and is expandable and contractible;
A second sub-liquid chamber communicating with the main liquid chamber via a second restriction passage; a deformable diaphragm forming a part of a partition wall of the second sub-liquid chamber; An air chamber, which is arranged so as to face the liquid chamber with the diaphragm interposed therebetween and in which a gas is sealed, and an open state in which the air chamber communicates with the atmosphere, and a space between the air chamber and the atmosphere is closed to close the air chamber. Closed
A switching valve that can take a closed state, a sensor that can detect the frequency of the vibration generated by the vibration generating unit, and a set frequency in which the frequency of the vibration generated by the vibration generating unit is preset based on the information from the sensor. If it is determined that the following, the switching valve is opened, and if it is determined that the frequency of the vibration generated by the vibration generator exceeds the set frequency, the switching valve is closed. It is characterized by that.

According to a second aspect of the present invention, in a vibration isolator, a first mounting member connected to one of the engine and the vehicle body, a second mounting member connected to the other of the engine and the vehicle body, and the first mounting member. An elastic body that is provided between the mounting member and the second mounting member and that deforms when vibration occurs; a main liquid chamber that is expandable and contractible using the elastic body as a part of a partition wall and that contains a liquid;
A first sub-liquid chamber that is in communication with the main liquid chamber via a first restriction passage and is expandable and contractible, and a second sub-liquid chamber that communicates with the main liquid chamber via a second restriction passage. A deformable diaphragm forming a part of a partition wall of the second sub liquid chamber, and an air chamber in which the second sub liquid chamber and the diaphragm are arranged so as to face each other with the diaphragm interposed therebetween and in which a gas is sealed. A switching valve that can take an open state in which the air chamber communicates with the atmosphere and a closed state in which the air chamber and the atmosphere are closed to close the air chamber, and a sensor that can detect the frequency of vibration generated by the engine. According to the information from the sensor, if the frequency of vibration generated by the engine is determined to be equal to or lower than the idle frequency, the switching valve is opened, and the frequency of vibration generated by the engine exceeds the idle frequency. If judged, switch the switching valve And control means for the chain state, characterized by comprising a.

[0010]

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

The vibration from the vibration generating section is transmitted to the elastic body via the first mounting member or the second mounting member.
At this time, the vibration is absorbed by the resistance based on the internal friction of the elastic body, and the main liquid chamber having the elastic body as a part of the partition wall is expanded / contracted so that the liquid flowing in the first restricted passage and the second restricted passage is It is absorbed by passage resistance or liquid column resonance.

In the first limiting passage and the second limiting passage, when a high-frequency vibration that cannot be absorbed occurs, that is, when a preset set frequency is exceeded, the sensor detects it. The control means operates the switching valve to close the air chamber and the atmosphere, which are located opposite to the second auxiliary liquid chamber with the diaphragm in between, by the switching valve to be in a closed state. By doing so, the rigidity of the diaphragm is increased as compared with the case where the air in the air chamber acts as an air spring and the switching valve is opened to open the air chamber and the atmosphere.

As a result, the frequency at which the liquid resonates in the second restriction passage moves to the high frequency side, and the dynamic spring constant of the vibration isolator decreases in the frequency range of high frequency vibration. That is, the characteristic of the vibration isolator can be changed by the switching valve depending on whether or not the air chamber is opened to the atmosphere, and the vibration can be absorbed over a wide frequency range.

The operation of the vibration isolator according to claim 2 will be described below. Shake vibration generated by the engine is transmitted to the elastic body via the first mounting member or the second mounting member. At this time, the shake vibration is absorbed by the resistance based on the internal friction of the elastic body, and the main liquid chamber having the elastic body as a part of the partition wall is expanded / contracted, so that the liquid flowing through the first restricted passage or the second restricted passage is It is absorbed by the passage resistance or liquid column resonance.

When an idle vibration having a frequency higher than that of the shake vibration is input to the vibration isolator, the first restriction passage becomes clogged, but at this time, the liquid resonates in the second restriction passage and the vibration isolator occurs. The dynamic spring constant of is reduced, and idle vibration can be absorbed.

In the first limiting passage and the second limiting passage, when vibration of a higher frequency than the idle vibration which cannot be absorbed occurs in the engine, the sensor detects it and the control means operates the switching valve. Then, the air chamber and the atmosphere, which are opposed to each other with the diaphragm interposed between the second auxiliary liquid chamber and the atmosphere, are closed by a switching valve to be in a closed state. By doing so, the rigidity of the diaphragm is increased as compared with the case where the air in the air chamber acts as an air spring and the switching valve is opened to open the air chamber and the atmosphere.

As a result, the frequency at which the liquid resonates in the second restriction passage moves to the high frequency side, and the dynamic spring constant of the vibration isolator decreases in the frequency range of high frequency vibration. That is, the characteristic of the vibration isolator can be changed by the switching valve depending on whether or not the air chamber is opened to the atmosphere, and the vibration can be absorbed over a wide frequency range.

As described above, when the engine is started, the engine speed increases above the engine speed set as the idle speed, but in accordance with this, the switching valve is closed to close the air chamber and the atmosphere. And Therefore, the characteristics of the anti-vibration device are changed so that the vibration in the anti-resonance region of the liquid does not occur even when the engine is started, and the vibration is absorbed even when the idling speed is exceeded.

That is, when the switching valve is opened, the dynamic spring constant of the vibration isolator decreases in the frequency range of idle vibration. Further, when the switching valve is closed, the dynamic spring constant of the vibration isolator decreases in the frequency range of high-frequency vibration having a higher frequency than idle vibration, for example, muffled noise.

[0020]

【Example】

[First Embodiment] A first embodiment of a vibration isolator according to the present invention is shown in FIGS. 1 to 4, and this embodiment will be described with reference to these drawings.

As shown in FIG. 1, a vibration isolator 1 of this embodiment.
0 is provided with a bottom plate 12 as a first mounting member. A mounting bolt 14 is projected from the lower center of the bottom plate 12, and as an example, the vibration isolator 10 is fixed to the body of an automobile (not shown) using the mounting bolt 14. Bottom plate 12
The circumference of is a cylindrical standing wall portion 12A bent at a right angle, and a flange portion 12B bent at a right angle is continuously formed at the upper end of the standing wall portion 12A.

A lower end portion of a cylindrical outer cylinder 16 is caulked and fixed to the flange portion 12B of the bottom plate 12, and a peripheral portion of the first diaphragm 18 is provided between the flange portion 12B and the lower end portion of the outer cylinder 16. Are pinched. A space between the first diaphragm 18 and the bottom plate 12 is a first air chamber 20, and the first air chamber 20 and the outside are communicated with each other through an air hole 21 formed in the standing wall portion 12A.

The upper end of the inner peripheral surface of the outer cylinder 16 is formed as a widened portion 16B having an enlarged inner diameter.
The outer periphery of the elastic body 22 that closes the opening of the outer cylinder 16 is vulcanized and bonded. Further, a part of the elastic body 22 is extended to the lower end of the inner periphery of the outer cylinder 16, and the outer peripheral side of the elastic body 22 is vulcanized and bonded to the outer cylinder 16.

A supporting base 24 as a second mounting member is vulcanized and adhered to the center of the elastic body 22. The support 24 is a mounting portion of an engine (not shown), and mounting bolts 26 for fixing the engine are provided upright.

A liquid chamber 28 is formed here by the inner peripheral portion of the outer cylinder 16, the lower end portion of the elastic body 22, the first diaphragm 18, and the like, and the liquid chamber 28 is filled with a liquid 29 such as ethylene glycol. Has been done.

A cylindrical partition member 30 made of synthetic resin or the like is arranged in the liquid chamber 28, and the liquid chamber 28 is divided into the main liquid chamber 32.
And a first sub liquid chamber 34. A concave portion 30A is formed on the first sub liquid chamber 34 side of the partition member 30.

A thin groove 44A having a rectangular cross section is formed on the outer periphery of the partition member 30 along the circumferential direction. 44A
At one end of the narrow groove 44B extending to the upper surface of the partition member 30.
And the opening 44C penetrating into the recess 30A is connected to the other end of the narrow groove 44A. Fine groove 44A, 44
The outer cylinder 16 side of B is closed by the extension of the elastic body 22 and serves as a first limiting passage 52 that connects the main liquid chamber 32 and the first sub liquid chamber 34.

Further, the partition member 30 is formed with a rectangular hole 42 from the outer periphery toward the center of the partition member 30.
As shown in FIG. 1, the tip of the rectangular hole 42 is bent upward and communicates with the main liquid chamber 32 through the opening 42A to form a second restriction passage 46.

A through hole 48 is formed in a side surface of the outer cylinder 16 at a position corresponding to the rectangular hole 42 of the partition member 30, and a block 50 is formed on the outer peripheral surface of the outer cylinder 16 corresponding to the through hole 48. Is attached.

A recess 54 is formed in the block 50, and a through hole 55 coaxial with the through hole 48 of the outer cylinder 16 is formed in the center of the bottom of the recess 54. The outer cylinder 1
A frame-shaped communication member 49 that penetrates a part of the elastic body 22 and connects the through hole 55 of the block 50 and the rectangular hole 42 of the partition member 30 is inserted into the through hole 48 of 6.

An annular recess 76 is formed in the block 50 outside the opening of the recess 54, and the peripheral edge of the second diaphragm 68 is sandwiched between the annular recess 76 and the block 78. The second diaphragm 68 projects substantially hemispherically toward the concave portion 54 in the free state. Therefore, the recess 54 is closed by the second diaphragm 68 to form the second auxiliary liquid chamber 70.

Further, the second diaphragm 6 of the block 78
On the surface facing 8, a substantially hemispherical concave portion 78 </ b> A is formed. A second air chamber 74 is provided between the concave portion 78A and the second diaphragm 68.

A main body 82A of a switching valve 82 as shown in FIGS. 1 to 3 is attached to the opposite side of the block 78 from the block 50 via a connecting pipe 80.
A coil housing 90 housing a coil 84 is connected to A via a tube 88. A plunger 86 is movably arranged in the tube 88, and a spring 92 is arranged between the proximal end side of the plunger 86 and the suction element 96 installed in the coil housing 90. . A packing 86A is attached to the tip of the plunger 86, and the block 78 and the connecting pipe 8 are attached.
0 and the main body 82A of the switching valve 82 to penetrate the second air chamber 7
4 and the L-shaped passage 94 that communicates with the atmosphere.
It can be shut off at 6A.

Therefore, when no voltage is applied to the coil 84, the plunger 86 is biased by the spring 92 and the packing 86A closes the passage 94, as shown in FIG. On the other hand, when a predetermined voltage is applied to the coil 84,
As shown in FIG. 3, the plunger 86 is attracted to the attractor 96 side by the electromagnetic force generated by the coil 84, the packing 86A at the tip of the plunger 86 escapes, and the passage 94 is opened.

The coil 84 is connected to the control circuit 60 which is a control means for turning on / off the applied voltage. The control circuit 60 is driven by the vehicle power supply, and can receive the detection signals from at least the vehicle speed sensor 98 and the engine speed sensor 99 to detect the vehicle speed and the engine speed. This allows the control circuit 60 to determine whether the vehicle is idling or shaking.

The passage length of the first limiting passage 52 is longer than the passage length of the second limiting passage 46, and the passage cross-sectional area of the first limiting passage 52 is the second limiting passage 46. It is smaller than the passage cross-sectional area.

The rigidity of the first diaphragm 18 and the second diaphragm 68 is different from each other, and the rigidity of the second diaphragm 68 is higher than that of the first diaphragm 18.

Here, the liquid column resonance frequency in the limiting passage is determined by the size of the limiting passage and the rigidity of the diaphragm, and the liquid column resonance frequency in the second limiting passage 46 is determined by the second diaphragm 68. It can be changed by changing the value of rigidity.

Next, the operation of the embodiment will be described. When the bottom plate 12 of the vibration isolator 10 is fixed to the body of a vehicle such as an automobile as an example, and the engine is mounted on the support 24 and fixed,
The vibration of the engine is supported on the vehicle body via the support 24, the elastic body 22, the outer cylinder 16 and the bottom plate 12, and the elastic body 2
The vibration is absorbed by the resistance based on the internal friction of No. 2.

Shaking vibration (for example, frequency less than 15 Hz) may occur when the vehicle travels at 70-80 km / h, for example. At this time, the liquid 29 moves back and forth between the main liquid chamber 32 and the first auxiliary liquid chamber 34 through the first restriction passage 52, and the resistance of the liquid 29 when the liquid 29 passes through the first restriction passage 52. A damping force is generated and the shake vibration is effectively absorbed. In the shake vibration, the second diaphragm 68 having high rigidity hardly deforms, and the flow of the liquid 29 hardly occurs in the second restriction passage 46.

Further, when the engine is idling or when the vehicle speed is 5 km / h or less, idle vibration (for example, a frequency of 20 to 50 Hz) occurs. Therefore, the set frequency can be preset to, for example, 50 Hz.

At the time of this idle vibration, the first restriction passage 52 is clogged. The control circuit 60 determines from the vehicle speed sensor 98 and the engine speed sensor 99 that idle vibration is occurring, and applies a voltage to the coil 84 of the switching valve 82 to attract the plunger 86. As a result, the second air chamber 74 is opened to the atmosphere, and the dynamic spring constant of the vibration isolator 10 in the vibration frequency range of idle vibration is reduced, so that idle vibration is reliably absorbed.

Further, when the engine is started, the engine speed set as the idle engine speed (for example, 700 rpm).
Although the engine speed increases more than m), the control circuit 60 determines that the engine is at high speed based on the information sent from the vehicle speed sensor 98 and the engine speed sensor 99. The application of voltage to the coil 84 is stopped. As a result, the plunger 8
The tip of 6 closes the passage 94, and the switching valve 82 is in a closed state that closes between the second air chamber 74 and the atmosphere.

As a result, the air in the second air chamber 74 serves as an air spring, so that the rigidity of the second diaphragm 68 is increased, and as a result, the second limiting passage 46 is increased.
The liquid column resonance frequency in (1) moves to the high frequency side, the dynamic spring constant in the frequency range of vibration at the time of high engine rotation decreases, and the vibration is reliably absorbed.

More specifically, the characteristic of the vibration isolator 10 changes from the solid line state shown in FIG. 4 to the dotted line state, so that 900-1200 rpm at the time of starting the engine.
Even if the engine is rotated at a high speed to some extent, the dynamic spring constant K is lowered and the vibration of the liquid in the anti-resonance region does not occur. Therefore, even if the idle speed is exceeded, vibration is absorbed.

That is, when the switching valve 82 is opened,
The dynamic spring constant of the vibration isolator 10 decreases in the frequency range of normal idle vibration. In addition, when the switching valve 82 is closed, the dynamic spring constant of the vibration isolator 10 decreases in the frequency range of high-frequency vibration having a higher frequency than the idle vibration at the time of starting the engine, which causes, for example, muffled noise.

Further, when the vehicle speed is 100 km / h or more and the engine speed is 3000 rpm or more, high frequency vibration (for example, a frequency of around 80 Hz) that causes muffled noise occurs. In this case as well, the control circuit 60 determines from the vehicle speed sensor 98 and the engine speed sensor 99 that the engine is in high frequency vibration, and the control circuit 60 causes the coil 84 to move.
Stop applying voltage to.

As a result, the plunger 8
Since the tip of 6 blocks the passage 94 and closes the second air chamber 74, the rigidity of the second diaphragm 68 is increased.

As described above, in the vibration damping device 10 of this embodiment, the vibration damping characteristics can be varied depending on whether the second air chamber 74 is opened to the atmosphere. Further, since the air in the second air chamber 74 facing the liquid is not sucked in by the intake system of the engine, even if the second diaphragm 68 is cut, the engine is not affected at all. Further, since the second diaphragm 68 is not sucked, the volume of the main liquid chamber 32 does not change, and the height of the vibration isolator 10 does not change.

[Second Embodiment] A second embodiment of the present invention is shown in FIG.
It is explained according to. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 5, the anti-vibration device 1 of the present embodiment.
The 0 outer cylinder 16 has a thick cylindrical shape, and a part of the lower part has a thin wall shape. A flange 30A is provided below the partition member 30 of the vibration isolator 10.

Further, the flange 30A of the partition member 30 and the peripheral portion of the first diaphragm 18 are sandwiched between the flange portion 12B of the bottom plate 12 and the lower end of the thick portion of the outer cylinder 16, and the outer cylinder 16 is thin-walled. It is fixed by caulking at the part.

A recess 62 is formed at a position on the outer peripheral side of the outer cylinder 16 corresponding to the rectangular hole 42 of the partition member 30.
The recess 62 is closed by a block 64.
A through hole 72 is formed at the bottom of the recess 62, and the through hole 72 communicates with the rectangular hole 42.

The bottom of the recess 62 and the through hole 72
An annular recess 66 is formed on the outer peripheral side of the second diaphragm 6 between the annular recess 66 and the block 64.
The peripheral portion of 8 is clamped. Second diaphragm 68
In the free state, the protrusions are formed in a substantially hemispherical shape toward the through hole 72 side, and the through hole 72 is closed by the second diaphragm 68 to form the second sub liquid chamber 70. Further, a concave portion 64A is formed on the side of the block 64 that faces the second diaphragm 68. A second air chamber 74 is formed between the recess 64A and the second diaphragm 68.
The second air chamber 74 and the switching valve 82 communicate with each other through a hole 64B formed in the block 64.

On the other hand, the partition member 30 has a recess 300 formed at the center on the main liquid chamber 32 side, and a diaphragm fixing pipe 302 is inserted and fixed in the recess 300.

On the inner peripheral surface of the diaphragm fixing pipe 302, an outer periphery of a disk-shaped third diaphragm 304 is vulcanized and bonded at an axially intermediate portion, and a space between the third diaphragm 304 and the bottom of the recess 300 is formed. Is the third air chamber 306. The third air chamber 306 does not communicate with the atmosphere.

Further, in this embodiment, the first diaphragm 1
The rigidity increases in the order of 8, the second diaphragm 68, and the third diaphragm 304.

Next, the operation of this embodiment will be described. During the shake vibration, the shake vibration is effectively absorbed by the resistance when the liquid 29 passes through the first restriction passage 52. In the shake vibration, the second diaphragm 6 having high rigidity is used.
8 and the third diaphragm 304 are hardly deformed, and the flow of the liquid 29 is hardly generated in the second restriction passage 46.

Further, at the time of idling vibration, the first restriction passage 52 becomes clogged. Therefore, the liquid 29
The main liquid chamber 32 and the second sub liquid chamber 7 pass through the second restriction passage 46.
Thus, the liquid column resonates in the second restriction passage 70. Note that the third diaphragm 304 having high rigidity is hardly deformed by idle vibration.

Then, similarly to the first embodiment, the control circuit 6
0 is determined by the vehicle speed sensor 98 and the engine speed sensor 99 that idle vibration is occurring, and the switching valve 82
A voltage is applied to the coil 84 to attract the plunger 86. As a result, the second air chamber 74 is opened to the atmosphere, and the dynamic spring constant of the vibration isolator 10 in the vibration frequency range of idle vibration is reduced, so that idle vibration is reliably absorbed.

Further, even when the engine is started, the same operation as in the first embodiment is performed, and therefore, the duplicated description will be omitted below.

When the vehicle speed is 100 km / h or more and the engine speed is 3000 rpm or more, high frequency vibration (for example, a frequency of around 80 Hz) that causes muffled noise occurs. In this case as well, the control circuit 60 determines from the vehicle speed sensor 98 and the engine speed sensor 99 that the engine is in high frequency vibration, and the control circuit 60 causes the coil 84 to move.
Stop applying voltage to.

As a result, the plunger 8
Since the tip of 6 closes the passage 94 and closes the second air chamber 74, the rigidity of the second diaphragm 68 increases, and
It works together with the diaphragm 304 to reduce the dynamic spring. [Third Embodiment] A third embodiment of the present invention will be described with reference to FIGS. The same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 6 and 7, the vibration isolator 10 of this embodiment is provided with a mounting frame 112 for mounting on a vehicle body (not shown).
An outer cylinder 116 is inserted into the annular portion 114 of 12.
A thin rubber layer 118 is vulcanized and adhered to the inside of the outer cylinder 116, and a part of the upper side of the thin rubber layer 118 is the outer cylinder 1.
The first diaphragm 120 is separated from the inner peripheral surface of 16, and the second diaphragm 121 is formed so that a part of the lower side thereof is separated from the inner peripheral surface of the outer cylinder 116 and is convex in a substantially spherical shape.

The space between the first diaphragm 120 and the outer cylinder 116 serves as a first air chamber 131, which is communicated with the outside if necessary. A second air chamber 137 is formed between the second diaphragm 121 and the outer cylinder 116.

An intermediate block 122 is provided inside the outer cylinder 116.
And an intermediate block 124 are inserted. Flange portions 122A are provided on both axial end portions of the intermediate block 122, respectively.
Are formed, and the outer peripheral surfaces of the flange portions 122A are in close contact with the thin rubber layer 118. The intermediate block 124 is fitted between the flange portions 122A. The intermediate block 124 has a substantially semicircular block shape when viewed from the axial direction of the outer cylinder 116, and has an outer peripheral surface in close contact with the thin rubber layer 118.

A notch 122B is formed in the central portion of the intermediate block 122 facing the intermediate block 124, and an inner cylinder 126 penetrates therethrough. The inner cylinder 126 is arranged coaxially with the outer cylinder 116, and an elastic body 128 is stretched between the inner cylinder 126 and the intermediate block 122. This allows the inner cylinder 126 to move relative to the outer cylinder 116.

A part of the outer peripheral surface of the elastic body 128 is in close contact with the top surface 124A of the intermediate block 124.
The main liquid chamber 13 is provided between the intermediate block 124 and the intermediate block 124.
A cutout 128A forming 0 is formed. Also,
The intermediate block 122, the intermediate block 124, and the thin rubber layer 11 are provided between the flange portions 122A of the intermediate block 122.
8 and a first diaphragm 120 which is partitioned by the first diaphragm 120.
A sub liquid chamber 132 is formed.

A passage 135 is provided on the outer periphery of the intermediate block 124.
Are formed. One end of the passage 135 is connected to the first sub-liquid chamber 132 and the other end is connected to the main liquid chamber 130 through the opening 135A. The passage 135 is surrounded by the outer cylinder 116 and has a first restriction for absorbing shake vibration. A passage 136 is formed.

A cutout portion 124B is formed in the lower portion of the intermediate block 124, and the cutout portion 124B is surrounded by the thin rubber layer 118 and the second diaphragm 121 to form a second auxiliary liquid chamber 133. . Further, one end of the intermediate block 124 is connected to the second auxiliary liquid chamber 133, and the other end is connected to the main liquid chamber 130 through an opening 134A formed in the inner peripheral portion of the intermediate block 124. A second limiting passage 134 for absorption is formed.

The main liquid chamber 130, the first auxiliary liquid chamber 132, the second auxiliary liquid chamber 33, the second limiting passage 134 and the first limiting passage 136 are filled with a liquid 29 such as ethylene glycol. Has been done.

The outer cylinder 11 corresponding to the second air chamber 137.
6 is formed with a circular hole 140 as an opening communicating with the inside and outside of the outer cylinder 116. The circular portion 114 has a circular hole 1
A circular hole 141 having the same diameter as the circular hole 140 is formed coaxially with the circular hole 40. A switching valve 82 is connected to the circular holes 140 and 141 via a connecting pipe 80.

On the other hand, in this embodiment, the passage length of the first limiting passage 136 is longer than that of the second limiting passage 134.
The passage cross-sectional area of the second limiting passage 134 is larger than that of the first limiting passage 136. In addition, the second diaphragm 121
Has a higher rigidity than the first diaphragm 120.

In this embodiment, the liquid column resonance frequency in the second limiting passage 134 can be changed by changing the rigidity value of the second diaphragm 121.

Next, the operation of this embodiment will be described. In the shake vibration, the shake when the liquid 29 passes through the first restriction passage 136 is effectively absorbed. In addition,
In the shake vibration, the second diaphragm 121 having high rigidity
Hardly deforms, and the liquid 29
There is almost no flow of.

Further, at the time of idling vibration, the first limiting passage 136 is clogged. Therefore, the liquid 29
Communicates with the main liquid chamber 132 through the second restriction passage 134
It will move back and forth with the sub liquid chamber 133.

At this time, the control circuit 60 determines from the vehicle speed sensor 98 and the engine speed sensor 99 that the idle vibration is occurring, and the coil 84 of the switching valve 82.
Is applied to attract the plunger 86. As a result, the second air chamber 137 is opened to the atmosphere, and the vibration control device 10 in the vibration frequency range of idle vibration is opened.
The dynamic spring constant of is reduced and the idle vibration is reliably absorbed.

Further, when the engine is started, the engine speed set as the idle engine speed (for example, 700 rp).
Although the engine speed increases more than m), the control circuit 60 determines that the engine is at high speed based on the information sent from the vehicle speed sensor 98 and the engine speed sensor 99. The application of voltage to the coil 84 is stopped. As a result, the plunger 8
The tip of 6 closes the passage 94, and the switching valve 82 is in a closed state that closes between the second air chamber 137 and the atmosphere.

As a result, the air in the second air chamber 137 acts as an air spring, so that the rigidity of the second diaphragm 121 is increased, and the liquid column resonance frequency in the second limiting passage 46 is increased. Moving to the high frequency side, the dynamic spring constant in the frequency range of the vibration at the time of high engine rotation is reduced, and the vibration is reliably absorbed.

That is, when the switching valve 82 is opened as in the first embodiment, the dynamic spring constant of the vibration isolator 10 decreases in the frequency range of normal idle vibration. In addition, the switching valve 8
When 2 is closed, the dynamic spring constant of the vibration isolator 10 decreases in the frequency range of high-frequency vibration that causes a muffled noise, which has a higher frequency than the idle vibration when the engine is started.

Further, when the vehicle speed is 100 km / h or more and the engine speed is 3000 rpm or more, high-frequency vibration (for example, a frequency of about 80 Hz) that causes muffled noise occurs. In this case as well, the control circuit 60 determines from the vehicle speed sensor 98 and the engine speed sensor 99 that the engine is in high frequency vibration, and the control circuit 60 causes the coil 84 to move.
Stop applying voltage to.

As a result, the plunger 8
Since the tip of 6 blocks the passage 94 and closes the second air chamber 137, the rigidity of the second diaphragm 121 is increased.

Further, in the above-mentioned embodiment, the construction in which the vibration isolator 10 is used as an engine mount is shown, but the present invention is not limited to this, and the vibration isolator 10 is used for a cab mount, a body mount, a support for general industrial machines, etc. Of course, it may be used for.

[0084]

As described above, the antivibration device of the present invention has an effect that the antivibration characteristics can be made variable.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vibration isolator according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a switching valve used in the vibration isolator according to the first embodiment of the present invention, showing a closed state.

FIG. 3 is an enlarged cross-sectional view of a switching valve used in the vibration isolator according to the first embodiment of the present invention, showing an open state.

FIG. 4 is a diagram showing a graph showing characteristics of the image stabilization device according to the first example of the present invention.

FIG. 5 is a cross-sectional view of a vibration control device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a vibration isolation device according to a third embodiment of the present invention.

FIG. 7 is an exploded perspective view of a vibration control device according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a graph showing the characteristics of a conventional image stabilization device.

[Explanation of symbols]

 10 Vibration Isolator 12 Bottom Plate (First Mounting Member) 18 First Diaphragm 22 Elastic Body 24 Supporting Base (Second Mounting Member) 32 Main Liquid Chamber 34 First Sub-Liquid Chamber 46 Second Limited Passage 52 First Restriction passage 60 Control circuit (control means) 68 Second diaphragm 70 Second auxiliary liquid chamber 74 Second air chamber 82 Switching valve 98 Vehicle speed sensor 99 Engine speed sensor 116 Outer cylinder (first mounting member) 120 First diaphragm 121 Second diaphragm 126 Inner cylinder (second mounting member) 128 Elastic body 132 First sub-liquid chamber 133 Second sub-liquid chamber 134 Second limiting passage 136 First limiting passage

Claims (2)

(57) [Claims] 1. A first mounting member connected to one of the vibration generating portion and the vibration receiving portion, a second mounting member connected to the other of the vibration generating portion and the vibration receiving portion, and the first mounting member. An elastic body that is provided between a member and the second mounting member and that deforms when vibration occurs; a main liquid chamber that is expandable and contractible using the elastic body as a part of a partition wall; A first sub-liquid chamber that communicates with the chamber via a first restriction passage and is expandable and contractible; a second sub-liquid chamber that communicates with the main liquid chamber via a second restriction passage; A deformable diaphragm forming a part of the partition wall of the second sub-liquid chamber; an air chamber that is arranged to face the second sub-liquid chamber with the diaphragm in between and is filled with a gas; the closed between an open state and the air chamber and the atmosphere to communicate with the atmosphere by sealing the air chamber A switching valve which can take a closed state, and a sensor capable of detecting the frequency of vibration generated from the vibration generating portion, the information of from the sensor, the following setting frequency whose frequency is preset by the vibration generating portion is generated If it is determined that the switching valve is opened, and the frequency of the vibration generated by the vibration generator exceeds the set frequency, the switching valve is closed. Anti-vibration device characterized by the above. 2. A first mounting member connected to one of the engine and the vehicle body, a second mounting member connected to the other of the engine and the vehicle body, the first mounting member and the second mounting member. An elastic body that is deformed when vibration occurs, a main liquid chamber that is expandable and contractible using the elastic body as a part of a partition wall, and liquid is sealed; A first sub-liquid chamber that is in communication with the main liquid chamber via a second restriction passage, and a partition wall of the second sub-liquid chamber. A deformable diaphragm forming a part, an air chamber arranged to face the second auxiliary liquid chamber with the diaphragm sandwiched therebetween and filled with gas, and an open state in which the air chamber communicates with the atmosphere, a closed state for sealing the air chamber closed between the air chamber and the atmosphere Switch valve, a sensor that can detect the frequency of the vibration generated by the engine, and the information from the sensor, if the frequency of the vibration generated by the engine is determined to be equal to or lower than the idle frequency, the switch valve is opened. And a control means for closing the switching valve when it is determined that the frequency of the vibration generated by the engine exceeds the idling frequency.