JP5069200B2 - Vibration isolator - Google Patents

Description

  The present invention relates to a fluid-filled vibration isolator that prevents transmission of vibration from a member that generates vibration, and more particularly, to a vibration isolator that is suitably used for an engine mount of an automobile.

  For example, in a vehicle such as a passenger car, a vibration isolator as an engine mount is disposed between an engine serving as a vibration generating unit and a vehicle body serving as a vibration receiving unit, and the vibration isolating device generates vibration generated from the engine. It is structured to absorb and prevent transmission to the vehicle body side. This type of anti-vibration device is provided with a main liquid chamber and a sub liquid chamber, and a plurality of restricting passages communicating with each of these liquid chambers in order to cope with vibrations of a wide range of frequencies, depending on the frequency of the input vibration. Thus, the plurality of restriction passages are selectively selected by a switching mechanism using the hydraulic pressure of the main liquid chamber so that the main liquid chamber and the sub liquid chamber communicate with each other through one restriction passage among the plurality of restriction passages. An anti-vibration device for switching is known (see, for example, Patent Documents 1 and 2).

In addition, when high-frequency vibration (for example, humming noise) in a high frequency range is input and the restriction passage becomes clogged, the fluid pressure in the main fluid chamber increases and the dynamic spring constant increases, that is, high-frequency vibration is effective. There is a problem that cannot be absorbed.
For this reason, the vibration isolator described in Patent Document 2 includes a piston that moves in the cylinder by the hydraulic pressure of the main liquid chamber as a switching mechanism, and at the time of high-frequency vibration input in which the restriction passage is clogged. A mechanism is provided that can elastically deform the membrane facing the main liquid chamber to suppress an increase in the liquid pressure in the main liquid chamber and suppress an increase in the dynamic spring.

Japanese Patent Laid-Open No. 2004-3615 JP 2007-120666 A

Incidentally, in recent years, vibration isolation devices have been required to effectively absorb vibrations in a wide frequency range (particularly on the high frequency range side such as booming noise). The vibration device has a problem in that it cannot effectively absorb vibration in a high frequency range that becomes a booming sound.
By providing a membrane as in the vibration isolator described in Patent Document 2, it has become possible to absorb vibrations in a high frequency range that could not be accommodated by the restricted passage. It has been.

Increasing the area of the membrane makes it easier for the membrane to vibrate when high-frequency vibration is input, so that the high-frequency vibration can be effectively absorbed, leading to improved performance of the vibration isolator.
Therefore, in order to more effectively absorb vibration in a high frequency range that causes a booming noise, it is necessary to secure a large area of the membrane. However, in the vibration isolator of Patent Document 2, a circular partition member is used. A rectangular cylinder chamber is arranged in the center of the cylinder, and membranes are arranged on both sides in the width direction, and a large-area membrane cannot be arranged.

  In other words, the cylinder chamber is arranged in the center of the partition surface, and the membranes are arranged in spaces opened on both sides in the width direction of the cylinder chamber, so that two membranes having a small area are arranged. The space that was opened in the room could not be used effectively for the membrane.

However, simply increasing the membrane area has the problem of increasing the size of the vibration isolator (increasing the diameter), and reducing the cylinder chamber cross-sectional area can increase the membrane area. If it is made smaller, the area of the piston becomes smaller, and there is a problem that the piston cannot be moved by the hydraulic pressure in the main liquid chamber, that is, the restriction passage cannot be switched.
The vibration isolator of Patent Document 1 has a configuration in which a circular cylinder chamber is provided in the center of a circular partition member. When a membrane is to be disposed, it is disposed in a narrow annular space around the cylinder chamber. Inevitably, it is difficult to effectively use the open space for the membrane.

  Further, as another problem, when the cylinder chamber is rectangular like the vibration isolator of Patent Document 2, the shape of the piston disposed therein is also rectangular. There is a concern that the restriction passage may not be switched well because it is inclined indoors and easily caught on the inner wall surface of the cylinder.

In view of the above fact, the object of the present invention is to switch the restriction passage with a piston that moves with the hydraulic pressure of the main liquid chamber, and to suppress the increase of the hydraulic pressure in the main liquid chamber during high-frequency vibration by elastic deformation of the membrane. In the vibration isolator, the first object is to improve the performance during high-frequency vibration by increasing the area of the membrane.
Further, in addition to the first object, the second object is to surely switch the restriction passage.

  As a result of various studies by the inventor, in the configuration in which the cylinder chamber is arranged in the center of the partition member and the membrane is arranged in the remaining empty space, there is a limit in securing a large membrane area by effectively using the empty space. The present inventors have found that by locating the cylinder chamber at a position displaced from the center of the partition member, it is possible to effectively utilize the empty space and secure a large membrane area.

  In order to achieve the above object, a vibration isolator according to claim 1 of the present invention includes a first attachment member connected to one of the vibration generating portion and the vibration receiving portion, and the other of the vibration generating portion and the vibration receiving portion. A second mounting member coupled to the first mounting member, an elastic body disposed between the first mounting member and the second mounting member, and a liquid sealed with the elastic body as a part of a partition, It is disposed between the main liquid chamber whose internal volume changes with elastic deformation of the elastic body, the sub liquid chamber in which the liquid is enclosed and the internal volume can be expanded and contracted, and the main liquid chamber and the sub liquid chamber. A partition member, a plurality of restricting passages having different anti-vibration characteristics for communicating the main liquid chamber and the sub liquid chamber with each other, a partition member, a cylinder chamber, and a cylinder chamber disposed inside the cylinder chamber, A piston that moves by the pressure of the main liquid chamber and switches the plurality of restriction passages. And a liquid liquid enclosed in the main liquid chamber when the restriction passage is clogged by vibration input, disposed on the surface of the partition member facing the main liquid chamber facing the main liquid chamber. A cylinder that elastically deforms so as to expand and contract the internal volume of the main liquid chamber according to a pressure change, and suppresses a pressure increase in the main liquid chamber, and the cylinder chamber when the main liquid chamber facing surface is viewed from the front The center portion of the main liquid chamber is displaced in a first direction from the center portion of the main liquid chamber facing surface toward the end portion of the main liquid chamber facing surface, and the membrane is arranged in the first direction with respect to the cylinder chamber. It is provided in a direction opposite to the direction.

The operation of the vibration isolator according to claim 1 of the present invention will be described below.
In the vibration isolator of claim 1, basically, when vibration is transmitted to one of the first and second mounting members, the elastic body disposed between the first and second mounting members is elastic. The vibration is absorbed by the vibration absorbing action based on the internal friction or the like of the elastic body, and the vibration transmitted to the vibration receiving portion side is reduced.

In the vibration isolator according to claim 1, the main liquid chamber and the sub liquid chamber communicate with each other through a plurality of restricting passages having different vibration isolating characteristics. In the vibration isolator according to the first aspect, the piston of the cylinder chamber is moved in accordance with the pressure of the main liquid chamber, and the restriction passage is switched.
Therefore, if the flow resistance of the liquid in a certain restricted passage is set (tuned) so as to correspond to the frequency and amplitude of the low-frequency vibration, the space between the main liquid chamber and the sub liquid chamber passes through the restricted passage. A resonance phenomenon (liquid column resonance) occurs in the liquid that comes and goes, and the action of the liquid column resonance can particularly effectively absorb the low-frequency vibration. In addition, if the passage resistance of the liquid in the other restricted passage is set so as to correspond to the vibration in the higher frequency range, the vibration in the higher frequency range can be absorbed particularly effectively by the other restricted passage.

  According to the vibration isolator according to the first aspect, the restriction passage is formed according to the pressure of the main liquid chamber without using a valve mechanism that operates in response to external control and power supply such as an electromagnetic solenoid or a pneumatic solenoid. The vibration can be effectively absorbed by the switched and switched restricted passages.

In the vibration isolator according to claim 1, the membrane is elastically deformed so as to expand and contract the internal volume of the main liquid chamber in accordance with a change in the liquid pressure of the liquid sealed in the main liquid chamber, so that elasticity at the time of vibration input is obtained. If the fluid pressure in the main fluid chamber changes periodically as the body deforms, the change in fluid pressure in the main fluid chamber can be suppressed by the membrane that elastically deforms according to this fluid pressure change, so the direction in which the main fluid chamber of the membrane expands or contracts If the rigidity along (stretching / reducing direction) is set so as to correspond to vibrations in a frequency range higher than the vibration frequency corresponding to the restriction passage, the restriction passage is clogged when high-frequency vibration is input. Thus, although it is difficult for the liquid to flow in the restriction passage, the membrane is elastically deformed in the expansion / contraction direction in synchronization with the high-frequency vibration, and the increase in the liquid pressure in the main liquid chamber can be suppressed.
As a result, the vibration isolator according to claim 1 can suppress an increase in the dynamic spring constant of the device (elastic body) due to an increase in the hydraulic pressure in the main liquid chamber even when high-frequency vibration is input. The dynamic spring constant of the elastic body is kept low, and high-frequency vibration can be effectively absorbed by the elastic deformation of the elastic body.

  Further, when the main liquid chamber facing surface is viewed from the front, the center portion of the cylinder chamber is displaced in the first direction from the central portion of the main liquid chamber facing surface toward the end of the main liquid chamber facing surface. Therefore, since a single vacant space is vacated in the direction opposite to the first direction with respect to the cylinder chamber on the surface facing the main liquid chamber, the membrane can be arranged by effectively using this vacant space. It becomes possible to arrange a membrane with one large area, and when a high frequency vibration is input, the membrane is easily elastically deformed, and the increase in the hydraulic pressure in the main liquid chamber can be effectively suppressed. .

  According to a second aspect of the present invention, in the vibration isolator according to the first aspect, when the main liquid chamber facing surface is viewed from the front, the shape of the main liquid chamber facing surface, the shape of the cylinder chamber, and the piston Each of the membranes is circular, and the membrane is formed in a curved shape along an arc portion of the outer peripheral edge of the main liquid chamber facing surface and an arc portion of the outer peripheral edge of the cylinder chamber.

  In the vibration isolator according to claim 2, since the shape of the cylinder chamber and the shape of the piston are each circular, the piston can be moved more smoothly in the cylinder chamber than when each is square, and the restricted passage Can be reliably switched.

In addition, when the main liquid chamber facing surface is circular, and the circular cylinder chamber is displaced in one direction from the center, the opposite side of the cylinder chamber from the displacement direction is a substantially crescent shape (the main liquid chamber facing surface). Along the arc part of the outer peripheral edge of the main liquid chamber facing surface and the arc part of the outer peripheral edge of the cylinder chamber (the radius of curvature is relatively small relative to the outer peripheral edge of the main liquid chamber facing surface) The curved shape)) is freed up.
In the vibration isolator according to claim 2, the membrane formed in the same shape (substantially crescent shape) as the vacant space is formed in the space vacated in the substantially crescent shape, so that the vacant space is used to the maximum extent. A large-area membrane that is easily elastically deformed by a change in hydraulic pressure can be disposed.

  According to a third aspect of the present invention, in the vibration isolator according to the first or second aspect, the hydraulic space defined on the main liquid chamber side of the piston by disposing the piston in the cylinder chamber; A check valve arranged between the main liquid chamber and capable of flowing liquid only in one direction between the main liquid chamber and the hydraulic pressure space in accordance with a change in hydraulic pressure in the main liquid chamber; An elastic member provided between the partition member and the main liquid chamber, in which the membrane is formed in part and the valve body of the check valve is formed in the other part of the valve body, An arc-shaped cut having a center of curvature at the center of the valve body is formed around the periphery.

In the vibration isolator according to claim 3, since the membrane member and the valve body of the check valve are integrally provided on the elastic member, the number of parts and the number of assembling steps can be reduced as compared with the case where they are formed individually. .
Further, since the arc-shaped cut having the center of curvature at the center of the valve body is formed around the valve body, the valve body can be easily moved.

As described above, since the vibration isolator according to claim 1 has the above-described configuration, it has an excellent effect that the membrane area can be increased to improve the performance during high-frequency vibration.
Since the vibration isolator according to claim 2 has the above configuration, it has an excellent effect that the restriction passage can be switched reliably.
In addition, since the vibration isolator according to claim 3 has the above-described configuration, the membrane and the valve body are integrated, so that the number of parts can be reduced.

Hereinafter, a vibration isolator 10 according to an embodiment of the present invention will be described with reference to the drawings. In the figure, symbol S represents the axial center of the apparatus, and the following description will be made with the direction along the axial center S as the axial direction of the apparatus.
As shown in FIG. 1 and FIG. 2, the vibration isolator 10 is provided with a cylindrical first outer cylinder 12 on the upper end side of the outer peripheral portion, and a cylindrical shape on the lower side of the first outer cylinder 12. The second outer cylinder 14 is connected and fixed. Note that the axis S coincides with the axis of the first outer cylinder 12 and the axis of the second outer cylinder 14.

The first outer cylinder 12 is formed with a bent flange portion 16 extending at the outer peripheral side at the lower end thereof.
The second outer cylinder 14 is formed with a bent flange portion 24 at the upper end thereof that extends outward. In the vibration isolator 10, the first outer cylinder 12 and the second outer cylinder 14 are caulked and fixed to each other by bending the outer peripheral side of the flange portion 24 toward the inner peripheral side so as to sandwich the outer peripheral side of the flange portion 16. .
In the vibration isolator 10, the first outer cylinder 12 or the second outer cylinder 14 is attached to a bracket 18, and is connected and fixed to the vehicle body side of the vehicle via the bracket 18.

The outer peripheral portion of the rubber elastic body 26 formed in a substantially cylindrical shape is vulcanized and bonded to the inner peripheral surface on the lower end side of the second outer cylinder 14 and extends upward from the upper end of the outer peripheral portion of the rubber elastic body 26. The thin-walled cylindrical covering portion 28 is vulcanized and bonded.
The rubber elastic body 26 is formed in a substantially inverted V shape whose cross-sectional shape is inclined upward from the outer peripheral side toward the inner peripheral side.

In the vibration isolator 10, a cylindrical mounting bracket 30 is disposed at the center portion of the second outer cylinder 14, and the inner peripheral surface of the rubber elastic body 26 is vulcanized and bonded to the outer peripheral surface of the mounting bracket 30. ing.
A screw hole 32 is formed in the mounting bracket 30 along the axis. In the vibration isolator 10, the mounting bracket 30 is connected and fixed to the engine-side mounting member 22 via the bolt 20 screwed into the screw hole 32.

As shown in FIGS. 1 and 3, a partition metal fitting 34 formed in a disc shape as a whole is fitted into the inner side of the outer cylinder 12 in the vibration isolator 10.
As shown in FIGS. 1 and 2, the partition fitting 34 divides the space on the inner peripheral side of the outer cylinders 12, 14 into two small spaces along the axial direction, and these two small spaces Are a main liquid chamber 36 and a sub liquid chamber 38 in which a liquid such as water or ethylene glycol is enclosed.
Here, the main liquid chamber 36 has the rubber elastic body 26 as a part of the partition wall, and its internal volume changes (expands / contracts) with the elastic deformation of the rubber elastic body 26.
The sub-liquid chamber 38 has a diaphragm 40 described later as a part of the partition wall, and the inner volume can be expanded and contracted by the deformation of the diaphragm 40.

  A rubber covering portion 42 formed in a thin film shape is vulcanized and bonded to the inner peripheral surface and the outer peripheral surface of the first outer cylinder 12, and the upper end portion of the covering portion 42 faces downward. The peripheral part of the rubber diaphragm 40 formed in an open inverted bowl shape is integrally joined over the entire circumference. The diaphragm 40 closes the upper end side of the first outer cylinder 12, and can be deformed so as to expand and contract the sub liquid chamber 38 with a sufficiently small load (hydraulic pressure).

As shown in FIGS. 1 to 3, a substantially cylindrical orifice member 44 made of a metal material such as a resin material or aluminum is provided on the upper side of the partition metal fitting 34.
On the main liquid chamber side of the orifice member 44, a cylinder chamber 60 that is recessed in a concave shape is formed at a position displaced from the axis S to one direction side of the radially outer peripheral side (arrow A direction side in FIG. 5). ing.
The cylinder chamber 60 has a circular cross-sectional shape orthogonal to the axis S, and a disc-shaped piston 78 described later is accommodated in the cylinder chamber 60 so as to be movable in the axial direction.

Further, a circular guide pin 50 extending in parallel with the axis S toward the cylinder chamber side is fixed to the bottom wall portion 60A of the cylinder chamber 60 toward the cylinder chamber side. And a plurality of (two) fixing holes 56 for fixing buffer rubber 54 described later.
The flow opening 48 allows the auxiliary liquid chamber 38 to communicate with a hydraulic space 112 of a cylinder chamber 60 described later.

  As shown in FIG. 4, the buffer rubber 54 has an annular shape, and a pair of protrusions 54 </ b> A for press-fitting into the fixing hole 56 of the bottom wall portion 60 </ b> A is formed. As shown in FIG. 1, the buffer rubber 54 is fixed to the bottom wall portion 60A by press-fitting the protrusion 54A into the fixing hole 56, so that the piston 78 does not contact the bottom wall portion 60A and generate sound. ing. The buffer rubber 54 is formed with a relief (notch) 54 </ b> B so as not to block the flow opening 48.

In the orifice member 44, a crescent recess 58 having a substantially crescent cross-sectional shape perpendicular to the axis S is formed on the side opposite to the cylinder chamber 60 when viewed from the axis S. It is formed to open. A plurality of through holes 62 are formed in the bottom 58 </ b> A of the crescent moon recess 58.
The orifice member 44 is formed with an annular flange portion 52 that extends to the outer peripheral side at the lower end side of the outer peripheral surface thereof.

  As shown in FIG. 1, the outer peripheral portion of the partition fitting 34, the flange portion 16 of the first outer cylinder 12, and the flange portion 52 of the orifice member 44 are caulked and fixed (clamped) by the flange portion 24 of the second outer cylinder 14. Is done. Thereby, the orifice member 44 and the partition fitting 34 are fixed and integrated with each other, and the orifice member 44 and the partition fitting 34 are fixed to the first outer cylinder 12 and the second outer cylinder 14.

As shown in FIG. 3, the lower end side of the orifice member 44 is closed by the partition metal fitting 34, whereby the cylinder chamber 60 of the orifice member 44 is partitioned from the outside, and the main liquid chamber 36 and the cylinder chamber 60 are also included in the cylinder chamber 60. The same liquid as the sub liquid chamber 38 is filled.
As shown in FIG. 5, an outer peripheral groove 66 extending in the circumferential direction is formed on the outer peripheral surface of the orifice member 44. The outer circumferential groove 66 circulates the outer circumferential surface of the orifice member 44 for a little less than one round, and has a substantially C-shape when viewed from the axial direction.

As shown in FIGS. 3 and 5, the orifice member 44 is formed with an upper communication hole 72 penetrating between one end portion of the outer peripheral groove 66 and the upper surface portion (sub liquid chamber side) of the orifice member 44. A lower communication hole 74 that penetrates between the other end portion of the outer peripheral groove 66 and the lower surface portion (main liquid chamber side) of the orifice member 44 is formed.
As shown in FIGS. 1 and 6, the orifice member 44 has an intermediate portion in the longitudinal direction of the outer peripheral groove 66 between the inner bottom surface of the outer peripheral groove 66 and the inner peripheral wall surface of the cylinder chamber 60. A penetrating orifice opening 76 is formed.
The orifice opening 76 opens to an inner wall surface (narrow wall surface) on one end side along the longitudinal direction of the cylinder chamber 60, and the opening shape is formed in a long and narrow slot shape along the circumferential direction of the cylinder chamber 60. Has been.

As shown in FIG. 1, in the vibration isolator 10, the outer peripheral surface of the orifice member 44 is covered in a state where the partition fitting 34 is fitted and inserted into the inner peripheral side of the first outer cylinder 12 and the second outer cylinder 14. It is press-contacted to the inner peripheral surface of the first outer cylinder 12 via the portion 42.
As a result, the outer peripheral side of the outer peripheral groove 66 of the orifice member 44 is closed by the inner peripheral surface of the covering portion 42 to form a shake orifice 118 that is one elongated space. One end of the shake orifice 118 serving as the first restriction passage is connected to the auxiliary liquid chamber 38 through the upper communication hole 72 of the orifice member 44, and the other end communicates with the main liquid chamber 36 through the lower communication hole 74. To do.
Here, the shake orifice 118 has a path length and a cross-sectional area, that is, a flow resistance of liquid so as to correspond to a shake vibration (for example, 9 to 15 Hz) which is a relatively low frequency vibration of the input vibration. It is set (tuned).

As shown in FIGS. 1 and 3, a piston 78 formed in a substantially disc shape is accommodated in the cylinder chamber 60 of the orifice member 44.
A boss 78B having a guide hole 78A penetrating in the axial direction is formed at the center of the piston 78, and the guide pin 50 of the cylinder chamber 60 is inserted into the guide hole 78A. The piston 78 is movable within a predetermined range (between an open position and a closed position described later) along the axial direction inside the cylinder chamber 60 while being guided by the guide pin 50.
The piston 78 divides the cylinder chamber 60 along the axial direction into a hydraulic space 112 which is a small space on the main liquid chamber 36 side and an orifice space 114 which is a small space on the sub liquid chamber 38 side.
The piston 78 is configured as a seal region 132 whose outer peripheral surface is in liquid-tight contact with the inner peripheral wall surface of the cylinder chamber 60 and is opposed with a minute gap.

The seal region 132 is formed such that the axial width thereof is larger than the axial width of the orifice opening 76 so that the orifice opening 76 can be closed.
The piston 78 is provided with a hydraulic pressure release passage 126 penetrating in the axial direction.
In the cylinder chamber 60, a compressed coil spring 86 is interposed between the piston 78 and the bottom wall portion 60A. The coil spring 86 moves the piston 78 to the main liquid chamber side (lower side). ).

In the partition metal fitting 34, a portion (two-dot chain line portion in FIG. 3) facing the cylinder chamber 60 is configured as a valve seat portion 88 of a check valve 116 described later. A guide hole 64 is drilled in the central portion, and a plurality of valve seat openings 90 are drilled on the outer peripheral side thereof. The partition member 34 is formed with a substantially crescent-shaped membrane opening 138 at a position facing the crescent recess 58 of the partition member 34, and a communication hole at a position facing the lower communication hole 74 of the orifice member 44. 100 is formed.
Here, the membrane opening 138 faces the crescent moon recess 58.

As shown in FIG. 3, a rib-shaped membrane pressing frame 140 is formed on the orifice member 44 along the peripheral edge portion of the membrane opening 138 of the partition metal 34 on the partition metal 34 side. .
A substantially disc-shaped elastic member 95 made of a rubber material such as NR or NBR is sandwiched between the partition fitting 34 and the orifice member 44.
The elastic member 95 is formed with a substantially crescent-shaped membrane (movable film) 146 at a position facing the crescent-shaped recess 58 and the membrane opening 138, and the lower communication hole 74 of the orifice member 44 and A communication hole 102 is formed at a position facing the communication hole 100. The membrane 146 is sandwiched and fixed between the membrane pressing frame 144 of the orifice member 44 and the partition fitting 34.

A circular valve body 98 is formed in the elastic member 95 at a position facing the cylinder chamber 60. A pair of substantially semicircular arc-shaped notches 98A are formed around the valve body 98, and the valve body 98 is connected to the outer peripheral side portion of the notch 98A via a pair of narrow support portions 98B. Yes.
The valve body 98 includes a protrusion 98 </ b> C that is inserted into the guide hole 64 of the partition member 34, and has an outer diameter that can abut against the valve seat portion 88 and close all the valve seat openings 90.
The central portion of the valve main body 98 is sandwiched and fixed between the end portion of the guide pin 50 and the partition fitting 34.

  A check valve 116 is constituted by the valve seat portion 88 of the partition member 34 and the valve main body 98 that contacts the valve seat portion 88. Normally, the valve main body 98 contacts the valve seat portion 88 and the cylinder chamber. The movement of the liquid from the 60 side to the main liquid chamber 36 side is blocked, and the movement of the liquid from the main liquid chamber 36 side to the cylinder chamber 60 side is allowed.

  As shown in FIGS. 1 and 5, the orifice space 114 of the cylinder chamber 60 is always in communication with the auxiliary liquid chamber 38 through a plurality of flow openings 48 formed on the upper surface side of the orifice member 44.

In the vibration isolator 10 of the present embodiment, the flow opening 48 of the partition metal 34, the orifice space 114 of the cylinder chamber 60, the orifice opening 76, and the outer peripheral groove 66 from the orifice opening 76 to the lower communication hole 74 are resistant to shake vibration. Thus, the idling orifice 120 corresponds to idling vibration (for example, 18 to 30 Hz) which is relatively high-frequency vibration.
That is, in this embodiment, a part of the shake orifice 118 (orifice opening 76 to lower communication hole 74) is common with a part of the idle orifice 120.

The idle orifice 120, which is the second restriction passage, is set (tuned) so that its path length and cross-sectional area, that is, the flow resistance of the liquid corresponds to idle vibration.
Here, the flow resistance of the liquid in the idle orifice 120 is smaller than the flow resistance of the liquid in the shake orifice 118.

  In the vibration isolator 10 of the present embodiment, as shown in FIG. 7, when the piston 78 moves (rises) to the closed position, the orifice opening 76 of the orifice member 44 is closed by the seal region 132 of the piston 78 and the orifice space. 114 is not in communication with the orifice portion of the outer peripheral portion of the orifice member 44. As a result, the main liquid chamber 36 and the sub liquid chamber 38 communicate with each other only through the shake orifice 118.

  The thickness (axial dimension) of the seal region 132 of the piston 78 is sufficiently thicker than the axial dimension of the orifice opening 76 on the inner peripheral surface of the cylinder chamber 60, and the liquid in the main liquid chamber 36 is formed. Even if the piston 78 vibrates along the axial direction as the pressure changes, the piston 78 can reliably maintain the orifice opening 76 in the closed state.

  On the other hand, as shown in FIG. 2, when the piston 78 moves (lowers) to the open position, the seal area 132 of the piston 78 moves away from the orifice opening 76 in the axial direction, the orifice opening 76 is opened, and the orifice space 114 becomes the orifice. The member 44 is in communication with the orifice (the common part of the shake orifice 118 and the idle orifice 120) in the outer peripheral portion of the member 44.

  Further, the hydraulic pressure release path 126 of the piston 78 causes the liquid in the hydraulic pressure space 112 closed from the outside to flow into the orifice space 114 when the piston 78 moves to the open position side by the biasing force of the coil spring 86. The hydraulic pressure in the hydraulic space 112 is prevented from increasing, and the piston 78 can be moved to the open position side.

As shown in FIG. 1, the membrane 146 of the elastic member 95 closes the lower end side of the crescent recess 58 of the orifice member 44, and faces the main liquid chamber 36 through the membrane opening 138 of the partition member 34.
Accordingly, when the hydraulic pressure in the main liquid chamber 36 changes, the membrane 146 elastically deforms so as to expand and contract the internal volume of the main liquid chamber 36 according to the change in the hydraulic pressure.

(Function)
Next, the operation of the vibration isolator 10 will be described.
In the vibration isolator 10, for example, when an engine in a vehicle is operated, vibration generated by the engine is transmitted to the rubber elastic body 26 via the mounting bracket 30, and the rubber elastic body 26 is elastically deformed. At this time, the rubber elastic body 26 acts as a main vibration absorber, and the vibration is absorbed by the vibration absorbing action based on the internal friction of the rubber elastic body 26 and the vibration transmitted to the vehicle body via the outer cylinders 12 and 14 is reduced. The

  In vehicles such as automobiles, the engine generates idle vibrations that are relatively high-frequency vibrations during idling, and the engine generates shake vibrations that are relatively low-frequency vibrations when traveling at a predetermined speed or higher. appear.

  Furthermore, in the vibration isolator 10, when the piston 78 moves from the open position to the closed position against the urging force of the coil spring 86 by the hydraulic pressure in the hydraulic space 112 of the cylinder chamber 60, the orifice opening 76 is closed. The orifice opening 76 is opened when the coil spring 86 is returned from the closed position to the open position by the biasing force of the coil spring 86. Therefore, when the piston 78 in the open position moves to the closed position when the shake vibration is input, the elasticity of the rubber elastic body 26 is reached. With the deformation, the liquid moves back and forth between the main liquid chamber 36 and the sub liquid chamber 38 only through the shake orifice 118, and when the piston 78 in the closed position returns to the open position when the idle vibration is input. Both the shake orifice 118 and the idle orifice 120 are opened, but with the elastic deformation of the rubber elastic body. Te, the back and forth of liquid between the flow resistance of the liquid is relatively small idle orifice 120 and preferentially through the main liquid chamber 36 and the auxiliary liquid chamber 38.

  That is, in the vibration isolator 10, when a shake vibration having a relatively low frequency and a large amplitude is input, the rubber elastic body 26 is elastically deformed by the shake vibration, and a relatively large liquid is contained in the main liquid chamber 36. As the pressure changes, the liquid flows from the main fluid chamber 36 into the hydraulic space 112 through the check valve 116 when the hydraulic pressure in the main fluid chamber 36 periodically increases, and the hydraulic pressure in the hydraulic space 112 is also main. The pressure rises to an equilibrium pressure that is substantially in equilibrium with the fluid pressure during the rise in the liquid chamber 36.

  Here, in the vibration isolator 10, the urging force of the coil spring 86 against the piston 78 is set to be smaller than a value corresponding to the hydraulic pressure (equilibrium pressure) in the hydraulic pressure space 112 when the shake vibration is input. Thus, when shake vibration is input, the piston 78 moves intermittently from the open position to the closed position against the urging force of the coil spring 86 and is held in the closed position by the hydraulic pressure in the hydraulic pressure space 112 ( The state of FIG.

  Therefore, in the vibration isolator 10, when shake vibration is input, the liquid moves back and forth between the main liquid chamber 36 and the sub liquid chamber 38 only through the shake orifice 118 in accordance with the elastic deformation of the rubber elastic body 26. Shake vibration transmitted from the vehicle side to the vehicle body side can be reduced. At this time, since the flow resistance of the liquid in the shake orifice 118 is set (tuned) so as to correspond to the frequency and amplitude of the shake vibration, the main liquid chamber 36 and the sub liquid chamber 38 pass through the shake orifice 118. A resonance phenomenon (liquid column resonance) occurs in the liquid flowing back and forth, and shake vibration can be absorbed particularly effectively by the action of the liquid column resonance.

  Further, in the vibration isolator 10, when an idle vibration having a relatively high frequency and a small amplitude is input, the rubber elastic body 26 is elastically deformed by the idle vibration and is relatively small in the main liquid chamber 36. Since the hydraulic pressure changes, in this case as well, liquid flows from the main hydraulic chamber 36 into the hydraulic pressure space 112 through the check valve 116 when the hydraulic pressure in the main hydraulic chamber 36 periodically increases, and the hydraulic pressure space 112 The fluid pressure in 112 rises to reach an equilibrium pressure that is substantially in equilibrium with the fluid pressure (maximum value) at the time of ascent in the main fluid chamber 36.

  However, in the vibration isolator 10, the urging force of the coil spring 86 is set to be larger than the value corresponding to the equilibrium pressure in the hydraulic pressure space 112 at the time of input of idle vibration, so that the piston 78 is in the open position. Is held in the open position by the biasing force of the coil spring 86, and when in the closed position, it is moved (returned) from the closed position to the open position by the biasing force of the coil spring 86 (state of FIG. 2). .

  Note that when the piston 78 moves to the open position side, the hydraulic pressure release passage 126 formed in the piston 78 causes the liquid in the hydraulic pressure space 112 closed from the outside to flow out into the orifice space 114. The piston 78 can be moved smoothly to the open position side with low movement resistance by preventing the hydraulic pressure in the hydraulic space 112 from increasing.

  Accordingly, in the vibration isolator 10, when the idle vibration is input, the main liquid chamber 36 is preferentially passed through the idle orifice 120 having a small liquid flow resistance with respect to the shake orifice 118 in accordance with the elastic deformation of the rubber elastic body 26. Since the liquid moves between the auxiliary liquid chamber 38 and the auxiliary liquid chamber 38, idle vibration transmitted from the engine side to the vehicle body side can be reduced.

  At this time, since the flow resistance of the liquid in the idle orifice 120 is set (tuned) so as to correspond to the frequency and amplitude of the idle vibration, the main liquid chamber 36 and the sub liquid chamber 38 pass through the idle orifice 120. A resonance phenomenon (liquid column resonance) occurs in the liquid flowing back and forth, and idle vibration can be absorbed particularly effectively by the action of the liquid column resonance.

  As a result, according to the vibration isolator 10, the main liquid chamber 36 and the sub liquid chamber 38 are communicated with each other without using a valve mechanism that operates in response to external control and power supply such as an electromagnetic solenoid or a pneumatic solenoid. The orifice to be switched can be switched to either the shake orifice 118 or the idle orifice 120 as a driving force in accordance with the frequency of the input vibration.

  In the vibration isolator 10 according to the present embodiment, a communication path 130 and a membrane opening 138 are provided on the outer peripheral side of the cylinder chamber 60 so as to communicate with the main liquid chamber 36 and the sub liquid chamber 38, respectively. Between the opening 138, a membrane 146 that is elastically deformed so as to expand and contract the internal volume of the main liquid chamber 36 in accordance with a change in the liquid pressure in the main liquid chamber 36 is provided, so that the vehicle has a peak of occurrence of shake vibration. If the vibration traveling at a speed higher than the speed and the vibration transmitted to the vibration isolator 10 is a vibration in a frequency range higher than the idle vibration and becomes a high-frequency vibration such as a booming sound having a small amplitude, the shake orifice 118 and the idle orifice 120 becomes clogged and the shake orifice 118 and the idle orifice 120 are difficult to flow liquid. 146 is elastically deformed so as to expand and contract the internal volume of the main liquid chamber 36 in synchronization with the input vibration, so that an increase in the liquid pressure in the main liquid chamber 36 can be suppressed. The rise of the dynamic spring constant of the device (rubber elastic body 26) due to the above can be suppressed, and the dynamic spring constant of the rubber elastic body 26 is kept low even when such high-frequency vibrations such as a booming sound are input. High-frequency vibrations can also be effectively absorbed by the elastic deformation of the elastic body 26.

  In the vibration isolator 10 of the present embodiment, the piston 78 having a circular cross section is disposed in the cylinder chamber 60 having a circular cross section, and therefore, the piston is smoother than when a piston having a rectangular cross section is disposed in the cylinder chamber having a rectangular cross section. 78 movements can be performed. Furthermore, in the vibration isolator 10 of this embodiment, since the center part of the piston 78 is supported by the guide pin 50, the inclination of the piston 78 can be further suppressed as compared with the case where the guide pin 50 is not provided.

  Moreover, in the vibration isolator 10 of this embodiment, since the shape of the cylinder chamber 60 and the shape of the piston 78 are each circular, the piston 78 is basically smoothly moved in the cylinder chamber in contrast to the configuration in which each is square. It is a structure that can be moved, and the switching of the restricted passage can be performed reliably.

  Further, as shown in FIG. 5, the main liquid chamber facing surface of the orifice member 44 is circular, and the cylinder chamber 60 having a circular cross section is displaced in one direction from the center, and is opposite to the displacement direction of the cylinder chamber 60. Since the membrane 146 formed in a substantially crescent shape similar to the vacant space is disposed in the vacant substantially crescent-shaped space, the large-area membrane 146 is formed using the vacant space on the opposite surface of the main liquid chamber to the maximum. I was able to place it. The membrane 146 having a large area is easily elastically deformed by a change in hydraulic pressure when high-frequency vibration is input, and can absorb high-frequency vibration such as a booming sound more effectively than before.

  In the vibration isolator 10, the mounting bracket 30 is connected to the engine side and the outer cylinders 12 and 14 are connected to the vehicle body side. Conversely, the mounting bracket 30 is connected to the vehicle body side. In addition to the connection, the outer cylinders 12 and 14 may be connected to the engine side. The vibration isolator 10 can also be used upside down.

It is sectional drawing along the axial direction which shows the structure of the vibration isolator which concerns on embodiment of this invention, and has shown the state which has a piston in an open position. It is sectional drawing along the axial direction which shows the structure of the vibration isolator made into a cross section in the position different from FIG. 1, and has shown the state which has a piston in an open position. It is a disassembled perspective view of the member which is arrange | positioned between the main liquid chamber and the subliquid chamber, and has divided both. It is a perspective view of a buffer rubber. It is the top view seen from the sub liquid chamber side of the orifice member. It is a perspective view of an orifice member and a partition metal fitting. It is sectional drawing along the axial direction which shows the structure of the vibration isolator which showed the state which has a piston in the obstruction | occlusion position.

Explanation of symbols

10 Vibration isolator 12 First outer cylinder (first mounting member)
14 Second outer cylinder (first mounting member)
26 Rubber elastic body (elastic body)
30 Mounting bracket (second mounting member)
34 Partition bracket (partition member)
36 Main liquid chamber 38 Sub liquid chamber 40 Diaphragm 44 Orifice member (partition member)
48 Distribution opening (switching means)
60 Cylinder chamber (switching means)
76 Orifice opening (switching means)
78 Piston (switching means)
86 Coil spring (switching means)
88 Valve seat (check valve)
98 Valve body (check valve: valve body)
98A notch
116 Check valve 118 Shake orifice (restricted passage)
120 Idle orifice (restricted passage)
146 membrane

Claims (3)

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 disposed between the first mounting member and the second mounting member;
A main liquid chamber in which a liquid is sealed with the elastic body as a part of a partition wall, and the internal volume changes with elastic deformation of the elastic body;
A secondary liquid chamber in which liquid is enclosed and the internal volume can be expanded and contracted;
A partition member disposed between the main liquid chamber and the sub liquid chamber;
A plurality of restricting passages having different anti-vibration characteristics communicating the main liquid chamber and the sub liquid chamber with each other;
A switching means provided in the partition member, comprising: a cylinder chamber; and a piston that is disposed inside the cylinder chamber and moves by the pressure of the main liquid chamber to switch the plurality of restriction passages;
When the restriction passage is clogged due to vibration input, the partition member is disposed on a surface facing the main liquid chamber facing the main liquid chamber, and according to a change in the liquid pressure of the liquid sealed in the main liquid chamber A membrane that elastically deforms so as to expand and contract the inner volume of the main liquid chamber and suppresses the pressure increase in the main liquid chamber;
With
When the main liquid chamber facing surface is viewed from the front, the center portion of the cylinder chamber is displaced in the first direction from the central portion of the main liquid chamber facing surface toward the end of the main liquid chamber facing surface. An anti-vibration device is provided, wherein the membrane is provided in a direction opposite to the first direction with respect to the cylinder chamber.   When the main liquid chamber facing surface is viewed from the front, the shape of the main liquid chamber facing surface, the shape of the cylinder chamber, and the shape of the piston are each circular, and the membrane is formed on the surface of the main liquid chamber facing surface. The vibration isolator according to claim 1, wherein the vibration isolator is formed in a curved shape along an arc portion of the outer peripheral edge and an arc portion of the outer peripheral edge of the cylinder chamber. By disposing the piston in the cylinder chamber, the piston is disposed between a hydraulic space partitioned on the main fluid chamber side of the piston and the main fluid chamber, and the main fluid chamber changes with a change in the fluid pressure in the main fluid chamber. A check valve capable of flowing liquid in only one direction between the liquid chamber and the hydraulic space;
An elastic member provided between the partition member and the main liquid chamber, wherein the membrane is formed in part and the valve body of the check valve is formed in the other part;
With
The anti-vibration device according to claim 1 or 2, wherein an arc-shaped cut having a center of curvature at the center of the valve body is formed around the valve body.

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