JP3761605B2 - Vibration isolator - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a vibration isolator that is used in vehicles, general industrial machines, and the like and absorbs and attenuates vibration from a vibration generating unit.
[0002]
[Prior art]
A vibration isolator as an engine mount is disposed between the engine and the vehicle body of the automobile so as to prevent the vibration of the engine from being transmitted to the vehicle body.
[0003]
The vibration generated by the engine includes so-called shake vibration that occurs when the vehicle is traveling at high speed, and so-called idle vibration that occurs when the vehicle is idling and when the vehicle is traveling at about 5 km / h. . In general, the frequency of the shake vibration is less than 15 Hz, whereas the frequency of the idle vibration is 20 to 50 Hz. The frequency is different between the shake vibration and the idle vibration.
[0004]
As an anti-vibration device that absorbs vibrations in a wide range of frequencies, the main liquid chamber and sub-liquid chamber are connected by an orifice, and a liquid-filled anti-vibration device that reduces vibration by the damping action associated with the flow of liquid in the orifice. The device is known.
[0005]
Further, as the liquid-filled vibration isolator, as shown in FIG. 7, a sub liquid chamber 212 is provided in a liquid chamber forming member 210 attached to the outer peripheral side of the vibration isolator, and the liquid chamber forming member 210 is provided. An air chamber 216 is provided in an air chamber forming member 214 connected to the screw 222, and the air pressure in the air chamber 216 disposed opposite the sub liquid chamber 212 via the diaphragm 218 is switched by a solenoid valve or the like. A vibration isolator that can be changed by the valve 220 to change the characteristics has been proposed.
[0006]
[Problems to be solved by the invention]
However, in the structure as shown in FIG. 7, the air chamber 216 and the outside air communicate with each other via the atmosphere side port 220A of the switching valve 220, so there is a risk that dust, foreign matter, etc. may enter the air chamber 216. there were.
[0007]
For this reason, a filter unit 230 having a filter 232 made of non-woven fabric or the like is attached to the switching valve 220 as a countermeasure against dust, foreign matter and the like entering the air chamber 216 via the switching valve 220. However, when such a filter unit 230 is mounted, an air resistance is generated by the filter 232, and the anti-vibration performance of the anti-vibration device is deteriorated compared to the case without a filter.
[0008]
That is, the minimum value of the dynamic spring constant K is higher and the frequency at which the dynamic spring constant K is the lowest when there is a filter indicated by the dotted line than when there is no filter indicated by the solid line in FIG. The band will shift and the anti-vibration performance will deteriorate.
[0009]
An object of the present invention is to provide an anti-vibration device that prevents foreign matter and the like from entering from the outside while preventing performance degradation due to air resistance, in order to solve the above-mentioned drawbacks.
[0010]
[Means for Solving the Problems]
The vibration isolator according to claim 1 is a first attachment member connected to one of the vibration generating unit and the vibration receiving unit;
A second attachment member coupled to the other of the vibration generating portion and the vibration receiving portion;
An elastic body provided between the first mounting member and the second mounting member and deformed when vibration occurs;
A main liquid chamber in which the elastic body can be expanded and contracted as a part of a partition wall and a liquid is enclosed;
A secondary liquid chamber communicated with the main liquid chamber via a restriction passage;
A deformable diaphragm constituting a part of the partition wall of the sub liquid chamber;
An air chamber disposed opposite to the sub liquid chamber and the diaphragm and filled with gas;
An air tank connected to the air chamber for accumulating gas, and performing intake and exhaust only between the air chamber;
The fluid chamber is disposed in a fluid path connecting the air chamber and the air tank, and the fluid passage is opened to open the air chamber in communication with the air tank; and the fluid passage is closed to close the air chamber and the air tank. And a switching valve that can be in a closed state that increases the rigidity with respect to the fluid pressure received from the liquid in the sub liquid chamber of the diaphragm, as compared with the case of being in the open state .
It is provided with.
[0011]
The vibration isolator according to claim 2 is characterized in that a wall portion defining a space in the air tank is formed of a tube-like elastic material.
[0012]
[Action]
The operation of the vibration isolator according to claim 1 will be described below.
[0013]
The vibration from the vibration generating unit 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 is also absorbed by the passage resistance of the liquid flowing through the restriction passage or the liquid column resonance by expanding and contracting the main liquid chamber using the elastic body as a part of the partition wall. The
[0014]
In this restricted passage, when high-frequency vibration that cannot be absorbed occurs, that is, when a preset set frequency is exceeded, an air chamber and an air tank that are located opposite to each other with the sub liquid chamber and the diaphragm interposed therebetween Is closed by a switching valve. In this way, the air in the air chamber separated from the space in the air tank acts as an air spring, and the switching valve is opened to open the communication between the air chamber and the air tank . The rigidity of the diaphragm with respect to the fluid pressure received from the liquid increases.
[0015]
As a result, the frequency at which the liquid resonates in the restricted passage moves to the high frequency side, and the dynamic spring constant of the vibration isolator decreases in the frequency region of high frequency vibration. That is, the characteristics of the vibration isolator can be arbitrarily changed by the switching valve depending on whether the air chamber is opened to the air tank side, and vibration can be absorbed over a wide frequency range.
[0016]
On the other hand, an air tank for storing gas is connected to the air chamber via a switching valve, and since this air tank performs intake and exhaust only between the air chamber, the air chamber and the switching valve are not communicated with outside air, No dust, foreign matter, etc. enter the air chamber and the switching valve from the outside.
[0017]
Further, since the air chamber and the switching valve are not in communication with the outside air, it is not necessary to install a filter. As a result, no air resistance is generated and the performance of the vibration isolator is not deteriorated.
[0018]
The operation of the vibration isolator according to claim 2 will be described below.
According to the present claim, the same effect as in the first aspect is obtained. However, since the wall that divides the space in the air tank is made of a tube-shaped elastic material, the air tank wall can be expanded and contracted even when the gas in the air tank expands and contracts as the temperature changes. can do.
[0019]
【Example】
A first embodiment of a vibration isolator according to the present invention is shown in FIGS. 1 to 5, and the present embodiment will be described based on these drawings.
[0020]
As shown in FIG. 1, a bottom plate 12 is provided in the lower part of the vibration isolator 10 of the present embodiment. A mounting bolt 14 projects from the bottom lower portion of the bottom plate 12 and, as an example, the vibration isolator 10 is fixed to a vehicle body (not shown) using the mounting bolt 14. The periphery of the bottom plate 12 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 portion of the standing wall portion 12A.
[0021]
The lower end portion of the cylindrical outer cylinder 16 is caulked and fixed to the flange portion 12B of the bottom plate 12, and the peripheral portion of the first diaphragm 18 is sandwiched between the flange portion 12B and the lower end portion of the outer cylinder 16. ing. A space between the first diaphragm 18 and the bottom plate 12 is a first air chamber 20, and the first air chamber 20 communicates with the outside through an air hole 21 formed in the standing wall portion 12A.
[0022]
The upper end portion of the inner peripheral surface of the outer cylinder 16 is an expanded portion 16B having an enlarged inner diameter. The outer periphery of the elastic body 22 that closes the opening portion of the outer cylinder 16 is vulcanized and bonded to the expanded portion 16B. Has been. 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 extended elastic body 22 is vulcanized and bonded to the outer cylinder 16.
[0023]
A support base 24 is vulcanized and bonded to the upper center of the elastic body 22. The support 24 is an engine mounting portion (not shown), and mounting bolts 26 for fixing the engine are provided upright.
[0024]
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 such as ethylene glycol.
[0025]
A cylindrical partition member 30 formed of synthetic resin or the like is disposed in the liquid chamber 28, and the liquid chamber 28 is partitioned into a main liquid chamber 32 and a first sub liquid chamber 34. A recess 30 </ b> A is formed on the partition member 30 on the first sub liquid chamber 34 side.
[0026]
On the outer periphery of the partition member 30, a narrow groove 44A having a rectangular cross section is formed along the circumferential direction. A narrow groove 44B extending to the upper surface of the partition member 30 is connected to one end of the narrow groove 44A, and an opening 44C penetrating to the recess 30A is connected to the other end of the narrow groove 44A. The narrow grooves 44 </ b> A and 44 </ b> B are closed on the outer cylinder 16 side by an extension of the elastic body 22, and serve as a first restriction passage 52 that communicates between the main liquid chamber 32 and the first sub liquid chamber 34.
[0027]
Furthermore, a rectangular hole 42 is formed in the partition member 30 from the outer periphery toward the center of the partition member 30, and as shown in FIG. 1, the tip of the rectangular hole 42 is bent upward to open the opening 42 </ b> A. The second restriction passage 46 is configured to communicate with the main liquid chamber 32 through the second restriction passage 46.
[0028]
A through hole 48 is formed at a position corresponding to the rectangular hole 42 of the partition member 30 on the side surface of the outer cylinder 16, and a block 50 is attached to the outer peripheral surface of the outer cylinder 16 corresponding to the through hole 48. ing.
[0029]
A concave portion 54 is formed in the block 50, and a through hole 55 that is coaxial with the through hole 48 of the outer cylinder 16 is formed at the bottom center of the concave portion 54. A frame-like communication member 49 that passes through a part of the elastic body 22 and communicates 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 the outer cylinder 16. ing.
[0030]
An annular recess 76 is formed in the portion of 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 protrudes in a substantially hemispherical shape toward the concave portion 54 in the free state. For this reason, the concave portion 54 is closed by the second diaphragm 68 to constitute the second sub liquid chamber 70.
[0031]
Further, a substantially hemispherical concave portion 78 </ b> A is formed on the surface of the block 78 facing the second diaphragm 68. A space between the recess 78A and the second diaphragm 68 is a second air chamber 74.
[0032]
As shown in FIGS. 1 to 4, a switching valve 82, which is an electromagnetic valve, is disposed at a position of the block 78 on the side opposite to the block 50. At the center of the switching valve 82 is a body 90 that is formed of a resin material in a cylindrical shape and around which a coil 84 is wound. A connecting pipe 90A that protrudes from the upper side of the body 90 to the right in the figure is blocked. It is fitted in 78 through holes 78B. An O-ring 91 is interposed between the connecting pipe 90A and the through hole 78B of the block 78 to seal between them.
[0033]
Further, an upper portion of the switching valve 82 is formed with a supply / exhaust pipe 90B protruding upward, and the passage in the connecting pipe 90A and the passage in the supply / exhaust pipe 90B are connected to bend the fluid. A flow path 94 is configured.
[0034]
Further, the coil case 102 forming the outer wall of the switching valve 82 houses the coil 84 which is a wire, and a connection terminal 98 is provided on the lower side of the coil case 102 to be connected to the coil 84 and energize the coil 84. ing.
[0035]
On the other hand, in the body 90, a plunger 86, which is a valve body formed in a columnar shape from a ferromagnetic steel material, is arranged so as to be movable in the vertical direction in the figure, and the base end side of the plunger 86 is A yoke iron core 96 is disposed oppositely, and a spring 92 is disposed between the plunger 86 and the yoke iron core 96.
[0036]
A packing 88 formed of rubber or the like is attached to the distal end side of the plunger 86 with an adhesive and attached to the body 90 in a cylindrical shape when the plunger 86 enters the fluid flow path 94. The packing 88 abuts on a receiving seat 90 </ b> C that is formed and serves as the inner wall surface of the fluid flow path 94. Therefore, the fluid flow path 94 that penetrates the connecting pipe 90 </ b> A and the supply / discharge pipe 90 </ b> B can be blocked by the plunger 86 and the packing 88.
[0037]
Further, as shown in FIG. 4, a coil cover 104 formed in a U shape so as to cover the lower side of the coil 84 is disposed on the outer peripheral portion of the switching valve 82. Further, as shown in FIGS. 2 and 3, a disk-like yoke plate 106 having a hole in the center is embedded at a position near the upper side of the body 90, and the yoke plate 106 protruding from the body 90 is The outer peripheral portion 106A is connected to the upper end portion of the coil cover 104 by welding or the like.
[0038]
The yoke iron core 96, the yoke plate 106, the coil cover 104, and the like are each formed of a ferromagnetic steel material, and thus form a magnetic path M surrounding the coil 84 when the coil 84 is energized. A yoke body is constituted by the yoke iron core 96, the yoke plate 106, the coil cover 104, and the like.
[0039]
As described above, the plunger 86 moves downward against the biasing force of the spring 92 by the electromagnetic force generated by the formation of the magnetic path M, and rises by the biasing force of the spring 92 as the magnetic path M disappears. Will move in the direction. For this reason, as the magnetic path M is formed and the magnetic path M disappears, the fluid flow path 94 is opened and closed by the plunger 86 entering and leaving the fluid flow path 94.
[0040]
In other words, when no voltage is applied to the coil 84, the plunger 86 is urged by the spring 92 as shown in FIG. Block. 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 yoke iron core 96 side by the electromagnetic force generated by the coil 84, and the packing 88 at the tip of the plunger 86 escapes and fluid The flow path 94 is opened, and air flows as indicated by an arrow A.
[0041]
The coil 84 is connected to a control circuit 60 that turns on and off the applied voltage. The control circuit 60 is driven by a vehicle power supply, and can detect the vehicle speed and the engine speed by receiving at least detection signals from the vehicle speed sensor 62 and the engine speed sensor 64. Thus, the control circuit 60 can determine whether the vehicle is idling or shaking.
[0042]
On the other hand, an opening 112 of an air tank 110 having a space 114 that is formed in a cylindrical shape and can store air is fitted in the supply / discharge pipe 90B of the switching valve 82 via a packing 116, and the switching is performed. An air tank 110 is installed above the valve 82.
[0043]
Therefore, the air that has flowed from the second air chamber 74 through the fluid flow path 94 of the switching valve 82 as shown by the arrow A in FIG. 3 flows into the space 114 in the air tank 110, and from the space 114 in the air tank 110. The air that has flowed out flows in the fluid flow path 94 as indicated by an arrow A, and air travels between the air tank 110 side and the second air chamber 74.
[0044]
The internal volume of the air tank 110 is larger than the internal volume of the second air chamber 74, and hopefully the internal volume of the air tank 110 is much larger than the internal volume of the second air chamber 74.
[0045]
The passage length of the first restriction passage 52 is longer than the passage length of the second restriction passage 46, and the passage cross-sectional area of the first restriction passage 52 is longer than the passage restriction of the second restriction passage 46. It is smaller than the area. Further, the rigidity of the first diaphragm 18 and the rigidity of the second diaphragm 68 are different from each other.
[0046]
Here, the liquid column resonance frequency in the restriction passage is determined by the size of the restriction passage and the rigidity of the diaphragm, and the liquid column resonance frequency in the second restriction passage 46 is determined as the rigidity value of the second diaphragm 68. It can be changed by changing.
[0047]
Next, the operation of the embodiment will be described.
Since the air tank 110 for storing air is connected to the second air chamber 74 via the switching valve 82, the second air chamber 74 and the switching valve 82 are not communicated with the outside air, and the second air chamber 74 and the switching are switched. No dust, foreign matter or the like enters the valve 82 from the outside.
[0048]
Further, since the second air chamber 74 and the switching valve 82 are not in communication with the outside air, it is not necessary to install a filter, and as a result, no air resistance is generated and the performance of the vibration isolator 10 is not deteriorated.
[0049]
On the other hand, the operation of the vibration isolator 10 according to this embodiment when vibration is generated will be described below.
[0050]
When the bottom plate 12 of the vibration isolator 10 is fixed to the body of a vehicle such as an automobile and the engine is mounted on the support base 24 and fixed, the vibrations of the engine are transmitted to the elastic body 22 via the support base 24. The vibration is absorbed by the resistance based on the internal friction of 22.
[0051]
Further, when the vehicle travels at, for example, 70 to 80 km / h, shake vibration (for example, frequency less than 15 Hz) may occur. At this time, the liquid goes back and forth between the main liquid chamber 32 and the first sub liquid chamber 34 through the first restriction passage 52, and the damping force due to the resistance when the liquid passes through the first restriction passage 52. And shake vibration is effectively absorbed. In shake vibration, the highly rigid second diaphragm 68 is hardly deformed, and almost no liquid flows in the second restricting passage 46.
[0052]
Further, when the engine is idling, or when the vehicle speed is 5 km / h or less, idle vibration (for example, frequency 20 to 50 Hz) occurs.
[0053]
During this idle vibration, the first restriction passage 52 is clogged. The control circuit 60 determines that the idling vibration is generated by the vehicle speed sensor 62 and the engine speed sensor 64 and applies a voltage to the coil 84 of the switching valve 82 to suck the plunger 86. As a result, the second air chamber 74 is brought into an open state in communication with the air tank 110, and the dynamic spring constant of the vibration isolator 10 in the vibration frequency region of idle vibration is reduced, so that idle vibration is reliably absorbed.
[0054]
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, around a frequency of 80 Hz) that causes a booming noise occurs. Also in this case, the control circuit 60 determines that the engine is in high-frequency vibration based on information sent from the vehicle speed sensor 62 and the engine speed sensor 64, and the control circuit 60 stops applying a voltage to the coil 84. As a result, the distal end of the plunger 86 closes the fluid flow path 94, and the switching valve 82 enters a closed state in which the space between the second air chamber 74 and the air tank 110 is closed.
[0055]
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, whereby the liquid column resonance frequency in the second restriction passage 46 is increased. And the dynamic spring constant in the frequency domain of vibration at the time of high engine rotation is reduced, and the vibration is reliably absorbed.
[0056]
Specifically, since the characteristic of the vibration isolator 10 changes from the solid line state shown in FIG. 5 to the dotted line state, even if a high rotation of 3000 rpm or more occurs in the engine, the dynamic spring constant K decreases, Vibrations in the antiresonance region of the liquid will not occur.
[0057]
That is, when the switching valve 82 is opened, the dynamic spring constant of the vibration isolator 10 decreases in the normal idle vibration frequency range. Further, when the switching valve 82 is closed, the dynamic spring constant of the vibration isolator 10 decreases in a frequency region of high frequency vibration that causes a higher noise frequency than idle vibration, for example.
[0058]
At this time, since the internal volume of the air tank 110 is larger than the internal volume of the second air chamber 74, the vibration isolation characteristics of the vibration isolation device 10 are affected by a change in the atmospheric pressure in the second air chamber 74. There is no.
[0059]
Next, a second embodiment of the vibration isolator according to the present invention is shown in FIG. 6, and this embodiment will be described based on this figure. In addition, the same code | symbol is attached | subjected to the member same as the member demonstrated in 1st Example, and the duplicate description is abbreviate | omitted.
[0060]
As shown in FIG. 6, an air tank 120 having a space 124 in which a wall 126 is formed of an elastic material such as rubber in a tube shape whose upper end is closed and in which air can be stored is provided in the switching valve 82. Installed at the top, the opening 122 of the air tank 120 is fitted into the supply / discharge pipe 90B of the switching valve 82.
[0061]
For this reason, the air that has flowed from the second air chamber 74 into the fluid flow path 94 of the switching valve 82 as indicated by arrow A flows into the space 124 in the air tank 120, and the air that has flowed out of the space 124 in the air tank 120. Flows in the fluid flow path 94 as indicated by an arrow A, and air travels between the air tank 120 side and the second air chamber 74.
[0062]
The inner volume of the air tank 120 is larger than the inner volume of the second air chamber 74, but can vary depending on the amount of air in the air tank 120.
[0063]
This embodiment also has the same effect as that of the first embodiment. Further, since the wall portion 126 that defines the space 124 in the air tank 120 is formed of a tube-like elastic material, it is accompanied by a change in the external temperature. Even if the gas in the air tank 120 expands and contracts, the wall 126 of the air tank 120 can be expanded and contracted.
[0064]
In addition, although the structure which uses the vibration isolator 10 as an engine mount was shown in the said Example, this invention is not limited to this, The vibration isolator 10 is used for the support of a cab mount, a body mount, a general industrial machine, etc. Of course, it is also good.
[0065]
【The invention's effect】
As described above, the vibration isolator of the present invention has the effect of preventing foreign matters and the like from entering from the outside while preventing performance degradation due to air resistance.
[Brief description of the drawings]
FIG. 1 is a cross-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 employed in the vibration isolator according to the first embodiment of the present invention, showing a closed state of the switching valve.
FIG. 3 is an enlarged cross-sectional view of the switching valve employed in the vibration isolator according to the first embodiment of the present invention, showing the open state of the switching valve.
FIG. 4 is a partial front sectional view of a switching valve employed in the vibration isolator according to the first embodiment of the present invention.
FIG. 5 is a graph showing characteristics of the vibration isolator according to the first embodiment of the present invention.
FIG. 6 is an enlarged cross-sectional view of a switching valve employed in a vibration isolator according to a second embodiment of the present invention.
FIG. 7 is an exploded perspective view around a switching valve employed in a conventional vibration isolator.
FIG. 8 is a graph showing characteristics of a conventional vibration isolator.
[Explanation of symbols]
10 Vibration isolator 12 Bottom plate (first mounting member)
22 Elastic body 24 Support base (second mounting member)
32 Main liquid chamber 46 Second restriction passage 68 Second diaphragm 70 Second sub liquid chamber 74 Second air chamber 82 Switching valve 110 Air tank 120 Air tank

Claims (2)

A first attachment member coupled to one of the vibration generator and the vibration receiver;
A second attachment member coupled to the other of the vibration generating portion and the vibration receiving portion;
An elastic body provided between the first mounting member and the second mounting member and deformed when vibration occurs;
A main liquid chamber in which the elastic body can be expanded and contracted as a part of a partition wall and a liquid is enclosed;
A secondary liquid chamber communicated with the main liquid chamber via a restriction passage;
A deformable diaphragm constituting a part of the partition wall of the sub liquid chamber;
An air chamber disposed opposite to the sub liquid chamber and the diaphragm and filled with gas;
An air tank connected to the air chamber for accumulating gas, and performing intake and exhaust only between the air chamber;
The fluid chamber is disposed in a fluid path connecting the air chamber and the air tank, and the fluid passage is opened to open the air chamber in communication with the air tank; and the fluid passage is closed to close the air chamber and the air tank. And a switching valve that can be in a closed state that increases the rigidity with respect to the fluid pressure received from the liquid in the sub liquid chamber of the diaphragm, as compared with the case of being in the open state .
An anti-vibration device comprising:   The anti-vibration device according to claim 1, wherein a wall portion defining a space in the air tank is formed of a tube-shaped elastic material.

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