Patent Publication Number: US-9897160-B2

Title: Vibration isolator

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/JP2015/057486 filed Mar. 13, 2015, claiming priority based on Japanese Patent Application Nos. 2014-122439 filed Jun. 13, 2014, the contents of all of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a vibration isolator which is applied to, for example, vehicles, industrial machines, etc. and absorbs and attenuates vibrations of vibration-generating parts such as engines. 
     Priority is claimed on Japanese Patent Application No. 2014-122439, filed Jun. 13, 2014, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     Constitutions such as that disclosed in, for example, Patent Document 1 are known as this type of vibration isolator. This vibration isolator includes a first tubular attachment member coupled to one of a vibration-generating part and a vibration-receiving part, a second attachment coupled to the other part, an elastic body configured to couple the attachment members to each other, a partition member configured to divide a liquid chamber in the first attachment member in which a liquid is sealed into a main liquid chamber having the elastic body as a portion of a wall surface and a subsidiary liquid chamber, and a movable member accommodated in an accommodating chamber provided at the partition member deformably in the axial direction of the first attachment member. A plurality of communicating holes extending outward in the axial direction from a portion of a wall surface of the accommodating chamber facing the movable member in the axial direction and configured to communicate the accommodating chamber with the main liquid chamber or the subsidiary liquid chamber are provided in the partition member. The communicating hole configured to communicate the accommodating chamber with the main liquid chamber among the plurality of communicating holes directly couples the accommodating chamber and the main liquid chamber in the axial direction. 
     DOCUMENT OF RELATED ART 
     Patent Document 
     Patent Document 1 
     Japanese Unexamined Patent Application, First Publication No. 2011-185291 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, the movable member may be deformed in the axial direction to come into contact with the wall surface of the accommodating chamber when the liquid pressure of the main liquid chamber varies based on the input from the vibration-generating part in the conventional vibration isolator, thereby generating large abnormal noise due to, for example, vibrations of the partition member, etc. 
     The present invention was made in view of the above-described circumstances, and an object of the present invention is to suppress abnormal noise occurring with input from the vibration-generating part. 
     Solution to Problem 
     A vibration isolator related to the present invention in which a plurality of communicating holes extending outward in an axial direction from a portion of a wall surface of an accommodating chamber facing a movable member in the axial direction and configured to communicate the accommodating chamber with a main liquid chamber or a subsidiary liquid chamber are provided in a partition member, and at least one of the plurality of communicating holes is a direct coupling hole configured to directly couple the accommodating chamber with the main liquid chamber or the subsidiary liquid chamber in the axial direction, the vibration isolator including: a first tubular attachment member coupled to one of a vibration-generating part and a vibration-receiving part and a second attachment member coupled to the other part; an elastic body configured to couple the attachment members to each other; the partition member configured to divide a liquid chamber in the first attachment member in which a liquid is sealed into the main liquid chamber having the elastic body as a portion of a wall surface and the subsidiary liquid chamber; the movable member accommodated in the accommodating chamber provided at the partition member deformably or displaceably in the axial direction of the first attachment member; and a flow control member positioned closer to an outside in the axial direction than the direct coupling hole and disposed to overlap the movable member in the axial direction through the direct coupling hole, wherein the flow control member does not come into contact with the movable member deformed or displaced in the axial direction when a liquid pressure of the main liquid chamber varies based on an input from the vibration-generating part. 
     In this case, the movable member is affected by a dynamic pressure of the liquid of the main liquid chamber or the subsidiary liquid chamber through the direct coupling holes when the liquid pressure of the main liquid chamber varies based on the input from the vibration-generating part, and a pressure difference occurs between the main liquid chamber and the subsidiary liquid chamber. At this time, the movable member is not directly affected by the dynamic pressure, but the movable member is affected by the dynamic pressure through the flow control member so that a direction and a size of a pressure gradient of the liquid in the vicinity of the movable member are changed due to the flow control member. Thus, for example, a deformation rate, a displacement rate, etc. of the movable member is suppressed when the movable member is deformed or displaced in the axial direction to come into contact with the wall surface of the accommodating chamber so that kinetic energy of the movable member can be suppressed. Also, in this case, since the movable member does not come into contact with the flow control member, abnormal noise can be suppressed. 
     As described above, abnormal noise can be suppressed by simply providing the flow control member, and abnormal noise can be suppressed without changing sizes of the direct coupling holes or a positional relationship between the partition member and the movable member. Therefore, abnormal noise can be suppressed while effects caused in characteristics of the vibration isolator such as, for example, frequency characteristics, attenuation characteristics, and cavitation characteristics are suppressed. 
     The movable member may include a fixed portion fixed to the partition member in the axial direction and may be formed deformably in the axial direction, and the flow control member may overlap a portion that is farthest from the fixed portion in a planar view of the partition member when viewed from the axial direction in an exposed area exposed from the direct coupling hole in the axial direction in the movable member in the axial direction. 
     In this case, since the movable member includes the fixed portion, a portion of the movable member which is farther from the fixed portion in the planar view is easily deformed in the axial direction. Here, since the flow control member overlaps the portion that is farthest from the fixed portion in the planar view in the exposed area of the movable member in the axial direction, a portion that is most easily deformed in the axial direction in the exposed area can be suppressed from being directly affected by the dynamic pressure of the liquid. Thus, abnormal noise can be effectively suppressed. 
     The exposed area of the movable member may be disposed on a hole axis of the direct coupling hole, the fixed portion may be provided at a portion other than the exposed area, and the flow control member may overlap a portion that is positioned at an opposite side of the fixed portion surrounding the hole axis in the exposed area in the axial direction and extend in a direction around the hole axis. 
     In this case, the flow control member overlaps the portion that is positioned at the opposite side of the fixed portion surrounding the hole axis of the direct coupling hole in the exposed area of the movable member in the axial direction and extends in the direction around the hole axis. Thus, a portion that is easily deformed in the axial direction in the exposed area of the movable member can be covered by the flow control member over a wide range so that abnormal noise can be more effectively suppressed. 
     Effects of Invention 
     According to the present invention, abnormal noise occurring with input from the vibration-generating part can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a longitudinal cross-sectional view of a vibration isolator according to an embodiment of the present invention. 
         FIG. 2  is a perspective view of a partition member constituting the vibration isolator shown in  FIG. 1 . 
         FIG. 3  is an enlarged view of a major part in the vibration isolator shown in  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described based on the drawings. 
     As shown in  FIG. 1 , a vibration isolator  10  includes a first tubular attachment member  11  coupled to one of a vibration-generating part and a vibration-receiving part, a second attachment member  12  coupled to the other part, an elastic body  13  configured to elastically couple the first attachment member  11  and the second attachment member  12 , and a partition member  15  disposed inside the first attachment member  11  and configured to divide a liquid chamber  16  formed inside the first attachment member  11  into a main liquid chamber  16   a  and a subsidiary liquid chamber  16   b.    
     Note that such members are provided coaxially with a central axis O. Hereinafter, a direction along the central axis O is referred to as an axial direction (an axial direction of the first attachment member), a direction perpendicular to the central axis O is referred to as a radial direction, and a direction around the central axis O is referred to as a circumferential direction. 
     Here, the above-described liquid chamber  16  is divided into the main liquid chamber  16   a  of one side in the axial direction (the upper side of  FIG. 1 ) having the elastic body  13  as a portion of a wall surface and the subsidiary liquid chamber  16   b  of the other side in the axial direction (the lower side of  FIG. 1 ) by the partition member  15 . 
     A liquid L such as, for example, ethylene glycol, water, or silicone oil is sealed in the main liquid chamber  16   a  and the subsidiary liquid chamber  16   b.    
     The vibration isolator  10  is mounted on, for example, a vehicle, etc. and suppresses vibration of an engine from being transferred to a vehicle body. In the vibration isolator  10 , the second attachment member  12  is coupled to the engine (not shown) serving as the vibration-generating part, and the first attachment member  11  is coupled to the vehicle body serving as the vibration-receiving part via a bracket (not shown). 
     The first attachment member  11  includes a first cylinder portion  11   a  formed at the one side in the axial direction, a second cylinder portion  11   b  formed at the other side in the axial direction, and a stepped portion  11   c  configured to couple the first cylinder portion  11   a  and the second cylinder portion  11   b . The first cylinder portion  11   a , the second cylinder portion  11   b , and the stepped portion  11   c  are disposed coaxially with the central axis O and formed as a single body. An end of the first attachment member  11  of the one side in the axial direction is closed by the elastic body  13  in a liquid-tight state and an end of the first attachment member  11  of the other side in the axial direction is closed by a diaphragm  14  in a liquid-tight state so that the liquid L can be sealed inside the first attachment member  11 . 
     The second attachment member  12  is disposed at the one side in the axial direction relative to the first cylinder portion  11   a  of the first attachment member  11 . 
     The elastic body  13  is a member made of, for example, a rubber material, etc. The elastic body  13  includes a deformation portion  13   a  protruding toward the one side in the axial direction from the end of the first attachment member  11  of the one side in the axial direction and having a truncated conical shape whose diameter is gradually decreased toward the one side in the axial direction and a covered portion  13   b  extending toward the other side in the axial direction along an inner circumferential surface of the first attachment member  11  from the deformation portion  13   a.    
     The covered portion  13   b  is vulcanization-adhered to the inner circumferential surface of the first attachment member  11 , and the inner circumferential surface of the first attachment member  11  is covered with the elastic body  13  over the entire area. The deformation portion  13   a  and the covered portion  13   b  are formed as a single body. 
     As shown in  FIGS. 1 and 2 , the partition member  15  is formed as a single body using, for example, an aluminum alloy, a resin, etc. The partition member  15  is formed in a discoid shape and is fitted into the first attachment member  11  (into the covered portion  13   b ). A first outer end surface  15   a  of the partition member  15  facing the one side in the axial direction faces the main liquid chamber  16   a , and the partition member  15  forms a portion of a partition of the main liquid chamber  16   a . A second outer end surface  15   b  of the partition member  15  facing the other side in the axial direction faces a side of the subsidiary liquid chamber  16   b , and the partition member  15  forms a portion of a partition of the subsidiary liquid chamber  16   b.    
     First and second concave portions  17   a  and  17   b , respectively, recessed inward in the axial direction are formed at the first outer end surface  15   a  and the second outer end surface  15   b . The first concave portion  17   a  which is the concave portion formed at the first outer end surface  15   a  and the second concave portion  17   b  which is the concave portion formed at the second outer end surface  15   b  are both disposed coaxially with the central axis O. 
     An accommodating chamber  18 , a thin portion  19 , and a restriction passage  20  are provided at the partition member  15 . The accommodating chamber  18 , the thin portion  19 , and the restriction passage  20  are independent of each other. 
     The accommodating chamber  18  is positioned between the first concave portion  17   a  and the second concave portion  17   b  in the axial direction. The accommodating chamber  18  is disposed to be shifted with respect to the central axis O. The accommodating chamber  18  is eccentric to the central axis O and intersects the central axis O. A part of the accommodating chamber  18  in the circumferential direction is open to the outside in the radial direction from an outer circumferential surface of the partition member  15 , and the remaining part thereof in the circumferential direction is closed from the outside in the radial direction. 
     An opening  21  which opens outward in the radial direction and a closed portion  22  positioned at the opposite side of the opening  21  surrounding the central axis O are provided at the accommodating chamber  18 . The closed portion  22  is surrounded by the first concave portion  17   a  and the second concave portion  17   b  in the axial direction. A size of the accommodating chamber  18  in the axial direction differs according to a position in forward and rearward directions along an opening axis of the opening  21 . The accommodating chamber  18  gradually becomes smaller in the axial direction from a rear side which is a side of the opening  21  in the forward and rearward directions toward a front side which is a side of the closed portion  22 . 
     End surfaces  18   a  and  18   b  in wall surfaces of the accommodating chamber  18  facing the inner side in the axial direction are both inclined with respect to the central axis O. The first inner end surface  18   a  at a side of the main liquid chamber  16   a  between the end surfaces  18   a  and  18   b  gradually extends toward the lower side (the other side in the axial direction) as it goes toward the front side, and the second inner end surface  18   b  at a side of the subsidiary liquid chamber  16   b  gradually extends toward the upper side (the one side in the axial direction) as it goes toward the front side. 
     The thin portion  19  is recessed toward the one side in the axial direction from the second concave portion  17   b  and is disposed to avoid the accommodating chamber  18 . 
     The restriction passage  20  communicates the main liquid chamber  16   a  with the subsidiary liquid chamber  16   b . The restriction passage  20  extends along the outer circumferential surface of the partition member  15  in the circumferential direction and is disposed to avoid the accommodating chamber  18  and the thin portion  19 . The restriction passage  20  is tuned such that resonance (liquid column resonance) occurs, for example, when engine shake vibrations with frequencies of approximately 10 Hz are input. 
     Here, a movable member  23  (a movable plate or a membrane) is disposed in the accommodating chamber  18 . The movable member  23  is accommodated in the accommodating chamber  18  deformably in the axial direction. For example, the movable member  23  is inserted into the accommodating chamber  18  toward the front side in the forward and rearward directions from the opening  21  of the accommodating chamber  18  so that the movable member  23  is accommodated in the accommodating chamber  18 . The movable member  23  is formed in a plate shape whose front and rear surfaces face the axial direction using, for example, a rubber material, etc. and can be elastically deformed. The movable member  23  is deformed in the axial direction according to a pressure difference between the main liquid chamber  16   a  and the subsidiary liquid chamber  16   b.    
     The movable member  23  has a shape similar to that of the accommodating chamber  18 . A thickness which is a size of the movable member  23  in the axial direction gradually becomes smaller toward the front side in the forward and rearward directions. An end of the movable member  23  of the rear side in the forward and rearward directions is a fixed end  24  (a fixed portion) fixed to the partition member  15  in the axial direction. The fixed end  24  is fitted into the opening  21  in a liquid-tight manner throughout the entire circumference of the opening  21  and regulates the liquid L in the accommodating chamber  18  from being leaked from the opening  21 . 
     A gap is formed between a deformation portion  25  positioned closer to the front side than the fixed end  24  in the movable member  23  and the wall surfaces of the accommodating chamber  18  over the entire area. A gap in the axial direction is formed between both surfaces facing the axial direction in the movable member  23  and the end surfaces  18   a  and  18   b  of the accommodating chamber  18 . 
     An end of the movable member  23  of the front side in the forward and rearward directions is a free end  26  which is farthest from the fixed end  24  in a planar view of the partition member  15  when viewed from the axial direction. The free end  26  is an end of the movable member  23  at an opposite side of the fixed end  24 . 
     Here, a plurality of communicating holes  27   a  and  27   b  (direct coupling holes) are further provided in the partition member  15 . The plurality of communicating holes  27   a  and  27   b  extend outward in the axial direction from a portion facing the movable member  23  in the axial direction in the wall surface of the accommodating chamber  18  and communicate the accommodating chamber  18  with the main liquid chamber  16   a  or the subsidiary liquid chamber  16   b . In the embodiment, the first communicating hole  27   a  configured to communicate the accommodating chamber  18  with the main liquid chamber  16   a  and the second communicating holes  27   b  configured to communicate the accommodating chamber  18  with the subsidiary liquid chamber  16   b  are provided as the communicating holes  27   a  and  27   b.    
     The first communicating hole  27   a  directly couples the accommodating chamber  18  and the main liquid chamber  16   a  in the axial direction and is open in the main liquid chamber  16   a  outward in the axial direction. One first communicating hole  27   a  is provided. 
     The first communicating hole  27   a  is provided at a bottom of the first concave portion  17   a . A hole axis O 1  of the first communicating hole  27   a  is shifted with respect to the central axis O. The first communicating hole  27   a  is larger in the axial direction than a gap between the surface of the movable member  23  and the first inner end surface  18   a  of the accommodating chamber  18  in the axial direction. 
     The first communicating hole  27   a  exposes a portion which is positioned closer to the rear side than the free end  26  in the deformation portion  25  of the movable member  23  toward the main liquid chamber  16   a  in the axial direction so that the fixed end  24  is not exposed. The movable member  23  is exposed over the entire area of the first communicating hole  27   a , and an exposed area  28  exposed in the axial direction from the first communicating hole  27   a  in the movable member  23  is disposed on the hole axis O 1  of the first communicating hole  27   a.    
     Regulating parts  29  protrude from an inner circumferential surface of the first communicating hole  27   a . The regulating parts  29  suppress the movable member  23  from being separated from the accommodating chamber  18  via the first communicating hole  27   a . The regulating parts  29  come into contact with the deformed movable member  23  and regulate further deformation of the movable member  23 . The plurality of regulating parts  29  are disposed at an interval in a direction around the hole axis O 1  of the first communicating hole  27   a . The regulating parts  29  do not protrude toward the outside in the axial direction from the first communicating hole  27   a.    
     A plurality of the second communicating holes  27   b  are provided. All of the second communicating holes  27   b  directly couple the accommodating chamber  18  and the subsidiary liquid chamber  16   b  in the axial direction and are open in the subsidiary liquid chamber  16   b  outward in the axial direction. The plurality of second communicating holes  27   b  are provided in a bottom of the second concave portion  17   b  at an interval. The second communicating holes  27   b  expose a portion positioned closer to the rear side than the free end  26  in the deformation portion  25  of the movable member  23  in the axial direction toward the subsidiary liquid chamber  16   b . The second communicating holes  27   b  are larger in the axial direction than a gap between the surface of the movable member  23  and the second inner end surface  18   b  of the accommodating chamber  18  in the axial direction. 
     Here, the vibration isolator  10  further includes a flow control member  30  (a flow control plate). The flow control member  30  is positioned at the outside in the axial direction relative to the first communicating hole  27   a  and is disposed to overlap the movable member  23  in the axial direction via the first communicating hole  27   a . Front and rear surfaces of the flow control member  30  are formed in a plate shape which faces the axial direction. The flow control member  30  is formed by a rigid body and has the same rigidity as the partition member  15 . Rigidity of the flow control member  30  is set to an extent that the flow control member  30  is not deformed, for example, when a dynamic pressure of the liquid L is exerted on the flow control member  30  based on an input from the vibration-generating part. 
     The flow control member  30  is disposed in the first concave portion  17   a  and is fixed to the partition member  17 . The flow control member  30  is smaller in the axial direction than the first concave portion  17   a  and the first communicating hole  27   a . The flow control member  30  is fixed to the bottom of the first concave portion  17   a  and is accommodated in the first concave portion  17   a . The flow control member  30  overlaps a portion of the exposed area  28  of the movable member  23  which is farthest from the fixed end  24  in the planar view in the axial direction. The flow control member  30  overlaps a portion of the exposed area  28  at the front side (the opposite side of the fixed end  24  surrounding the hole axis O 1  of the first communicating hole  27   a ) in the axial direction and extends in a direction around the hole axis O 1  of the first communicating hole  27   a.    
     The flow control member  30  continuously extends around the hole axis O 1  and covers a portion of the exposed area of the movable member  23  at the front side over the entire area around the hole axis O 1 . 
     A part of the flow control member  30  covers the exposed area  28  of the movable member  23  in the axial direction, and the remaining part thereof is fixed to the partition member  15 . In the embodiment, a rear portion of the flow control member  30  at the rear side covers the exposed area  28  in the axial direction, and a front portion thereof at the front side is fixed to the bottom of the first concave portion  17   a . The front portion of the flow control member  30  is fixed to the bottom of the first concave portion  17   a  using bolts  31 . The rear portion of the flow control member  30  is adjacent to the first communicating hole  27   a  in the axial direction. The rear portion of the flow control member  30  does not come into contact with the movable member  23  deformed in the axial direction when a liquid pressure of the main liquid chamber  16   a  varies based on the input of the vibration-generating part. The flow control member  30  is away from the movable member  23  regardless of the presence or absence of the input from the vibration-generating part. 
     Next, an action of the vibration isolator  10  with such a constitution will be described. 
     The movable member  23  is deformed in the accommodating chamber  18  in the axial direction when vibrations (e.g., idle vibrations with frequencies of approximately 30 Hz) with minute amplitudes (e.g., ±0.2 mm or less) are exerted on the vibration isolator  10 , and pressure of the liquid L in the main liquid chamber  16   a  varies. Thus, the vibrations can be absorbed and attenuated. 
     The movable member  23  comes into contact with the end surfaces  18   a  and  18   b  of the accommodating chamber  18  in the partition member  15  to close the communicating holes  27   a  and  27   b  when vibrations with greater amplitudes than the above-described minute amplitudes (e.g., engine shake vibrations with frequencies of approximately 10 Hz) are exerted on the vibration isolator  10 , and the pressure of the liquid L in the main liquid chamber  16   a  varies. In this case, the liquid L flows between the main liquid chamber  16   a  and the subsidiary liquid chamber  16   b  through the restriction passage  20 , and liquid column resonance occurs. Thus, the vibrations can be absorbed and attenuated. 
     As described above, according to the vibration isolator  10  related to the embodiment, the movable member  23  is affected by a dynamic pressure of the liquid L of the main liquid chamber  16   a  through the first communicating hole  27   a  when the liquid pressure of the main liquid chamber  16   a  varies based on the input from the vibration-generating part, and a pressure difference occurs between the main liquid chamber  16   a  and the subsidiary liquid chamber  16   b . In this case, as shown by arrows in  FIG. 3 , the movable member  23  is not directly affected by the dynamic pressure, but the movable member  23  is affected by the dynamic pressure through the flow control member  30  so that a direction and a size of a pressure gradient of the liquid L in the vicinity of the movable member  23  are changed due to the flow control member  30 . Thus, for example, a deformation rate, etc. of the movable member  23  is suppressed when the movable member  23  is deformed in the axial direction to come into contact with the wall surface of the accommodating chamber  18  so that kinetic energy of the movable member  23  can be suppressed. Also, in this case, since the movable member  23  does not come into contact with the flow control member  30 , abnormal noise can be suppressed. 
     As described above, abnormal noise can be suppressed by simply providing the flow control member  30 , and abnormal noise can be suppressed without changing sizes of the communicating holes  27   a  and  27   b  or a positional relationship between the partition member  15  and the movable member  23 . Therefore, abnormal noise can be suppressed while effects caused in characteristics of the vibration isolator  10  such as, for example, frequency characteristics, attenuation characteristics, and cavitation characteristics are suppressed. 
     Since the movable member  23  includes the fixed end  24 , a portion of the movable member  23  which is farther from the fixed end  24  in the planar view is easily deformed in the axial direction. Here, since the flow control member  30  overlaps a portion of the exposed area  28  of the movable member  23  which is farthest from the fixed end  24  in the planar view in the axial direction, a portion of the exposed area  28  which is most easily deformed in the axial direction can be suppressed from being directly affected by the dynamic pressure of the liquid L. Thus, abnormal noise can be effectively suppressed. 
     Also, the flow control member  30  overlaps a portion of the exposed area  28  of the movable member  23  at the front side in the axial direction and extends in a direction around the hole axis O 1  of the first communicating hole  27   a . Thus, a portion of the exposed area  28  of the movable member  23  which is easily deformed in the axial direction can be covered by the flow control member  30  over a wide range so that abnormal noise can be effectively suppressed. 
     Note that the technical scope of the present invention is not limited to the embodiments and can be modified in various ways without departing from the gist of the present invention. 
     For example, while the first concave portion  17   a , the second concave portion  17   b , the thin portion  19 , and the restriction passage  20  are provided in the embodiment, they may be omitted. 
     The flow control member  30  overlaps the portion of the exposed area  28  of the movable member  23  which is farthest from the fixed end  24  in the planar view in the axial direction in the embodiment, but the present invention is not limited thereto. 
     The flow control member  30  is disposed to overlap the movable member  23  in the axial direction through the first communicating hole  27   a  in the embodiment, but the present invention is not limited thereto. For example, the flow control member  30  may be disposed to overlap the movable member  23  in the axial direction through the second communicating holes  27   b . In this case, the flow control member  30  may not be disposed to overlap the movable member  23  in the axial direction through the first communicating hole  27   a.    
     A size, a material, rigidity, etc. of the flow control member  30  can also be appropriately changed. A surface of the flow control member  30  may be even or uneven. The flow control member  30  can also be integrally formed with the partition member  15 . 
     The second communicating holes  27   b  directly couple the accommodating chamber  18  and the subsidiary liquid chamber  16   b  in the axial direction in the embodiment, but the present invention is not limited thereto. For example, ends of the second communicating holes  27   b  of the outside in the axial direction may be communicated with the subsidiary liquid chamber  16   b  through another flow path extending in a direction perpendicular to the central axis O. An end of the first communicating hole  27   a  of the outside in the axial direction can also be communicated with the main liquid chamber  16   a  through the other flow path extending in the direction perpendicular to the central axis O when the flow control member  30  is not disposed to overlap the movable member  23  in the axial direction through the first communicating hole  27   a.    
     A different constitution from the embodiment may be adopted as the accommodating chamber  18 . For example, the accommodating chamber  18  may have the same size in the axial direction over the entire length of the forward and rearward directions. The accommodating chamber  18  may be open toward both sides in the radial direction surrounding the central axis O and may be closed throughout the entire circumference. 
     A different constitution from the embodiment may be adopted as the movable member  23 . For example, a central portion (the fixed portion) in the planar view in the movable member  23  may be fixed in the axial direction. The movable member  23  may be displaceably accommodated in the accommodating chamber  18  in the axial direction, and another constitution in which the movable member  23  is accommodated in the accommodating chamber  18  deformably or displaceably in the axial direction can also be appropriately adopted. 
     The case in which the second attachment member  12  and the engine are connected and the first attachment member  11  and the vehicle body are connected has been described in the embodiment. However, the present invention is not limited thereto, a constitution in which these connections are reversed is also possible, and the vibration isolator  10  may be installed at another vibration-generating part or vibration-receiving part. 
     In addition, the constituent elements of the above-described embodiment can be appropriately replaced with well-known constituent elements without departing from the gist of the present invention, and appropriately combined with the modified example described above. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, abnormal noise occurring with input from the vibration-generating part can be suppressed. 
     REFERENCE SIGNS LIST 
     
         
           10 : vibration isolator 
           11 : first attachment member 
           12 : second attachment member 
           13 : elastic body 
           15 : partition member 
           16 : liquid chamber 
           16   a : main liquid chamber 
           16   b : subsidiary liquid chamber 
           18 : accommodating chamber 
           23 : movable member 
           24 : fixed end (fixed portion) 
           27   a : first communicating hole (direct coupling hole) 
           27   b : second communicating hole (direct coupling hole) 
           28 : exposed area 
           30 : flow control member 
         L: liquid 
         O 1 : hole axis