Anti-vibration device

Abstract

To provide a vibration control device in a novel structure which enables the control of vibration control characteristics with excellent energy efficiency, by efficiently applying a control magnetic force to filled magnetic function fluid.SOLUTION: A vibration control device 10 controls vibration control characteristics by applying magnetic force from a magnetic field generation unit 56 to an orifice passage 40 communicating between fluid chambers 38, 38 filled with magnetic function fluid 39. An intermediate cylindrical member 24 to which an outer cylindrical member 16 formed of non-magnetic material is externally fitted and fixed is formed of a ferromagnetic material, and a magnetic field operation opening part 32 is provided in the intermediate cylindrical member 24 at its position corresponding to the orifice passage 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fluid-filled vibration-damping device that utilizes the flow action of a fluid sealed in an internal fluid chamber, and in particular to a fluid-filled vibration-damping device that employs a magnetic functional fluid whose flow characteristics change with changes in the magnetic field. [Background technology]

[0002] A known type of vibration isolation device is a fluid-filled type vibration isolation device that has a structure in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, and that uses the flow action of a fluid sealed inside to provide a vibration isolation effect against input vibration between the inner shaft member and the outer cylindrical member. Such fluid-filled type vibration isolation devices can be used not only in vehicle engine mounts, but also in a wide range of applications such as cab mounts, differential mounts, suspension mounts, and vibration isolation bushings.

[0003] However, since the vibration isolation characteristics required of a vibration isolation device vary depending on the input vibration and the vehicle's running conditions, it is desirable that the vibration isolation characteristics obtained by utilizing the flow action of the fluid be externally controllable.

[0004] Therefore, Japanese Patent Laid-Open Publication No. 3-009139 (Patent Document 1) proposes an electrorheological fluid-filled vibration-damping device that employs an electrorheological fluid whose viscosity changes when electricity is passed through it, and that makes it possible to switch vibration-damping characteristics by controlling the passage of electricity through the electrorheological fluid. However, with a vibration-damping device such as that described in Patent Document 1, electrodes for passing electricity must be provided inside so as to be in contact with the electrorheological fluid, and electricity must be supplied to these electrodes from the outside, which can easily make the structure and manufacturing complicated.

[0005] Meanwhile, German Patent Application Publication No. 102011117749 (Patent Document 2) proposes an anti-vibration device that uses a magnetorheological fluid, whose viscosity changes depending on the strength of the applied magnetic field. Because magnetorheological fluids can be controlled by applying a magnetic field from outside the fluid chamber, there is no need to place current-carrying electrodes inside the fluid chamber as with electrorheological fluids, and the manufacturing of the anti-vibration device structure can be simplified compared to electrorheological fluid-filled types. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 3-009139 [Patent Document 2] German Patent Application Publication No. 102011117749 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the magnetic field generating unit that applies a magnetic field to the magnetorheological fluid is provided outside the fluid chamber, it is difficult to efficiently apply the magnetic field generated by the magnetic field generating unit to the magnetorheological fluid.

[0008] Specifically, it is conceivable to attach a magnetic field generating unit in an extrapolated state to the outer peripheral surface of the outer cylindrical member, as shown in Figures 2 and 3 of Patent Document 2. However, no consideration has been given to how to efficiently apply the magnetic field generated by such a magnetic field generating unit to the orifice passage of the magnetorheological fluid sealed in the fluid chamber, and as a result, there have been problems such as the intended vibration damping characteristics not being fully exhibited and excessive magnetic field generation capacity being required of the magnetic field generating unit, resulting in poor energy efficiency.

[0009] The problem to be solved by the present invention is to provide a vibration-damping device with a novel structure that can efficiently apply the magnetic field from a magnetic field generating unit to the magnetorheological fluid sealed in the fluid chamber, thereby switching the vibration-damping characteristics with good energy efficiency. [Means for solving the problem]

[0010] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0011] A first aspect of the present invention is as follows. A fluid-filled vibration-damping device in which an inner shaft member and an intermediate cylindrical member are connected by a main rubber elastic body, an outer cylindrical member is fitted onto and fixed to the intermediate cylindrical member, a pocket-like portion provided in the main rubber elastic body and opening to the outer periphery of the intermediate cylindrical member is covered with the outer cylindrical member to form a plurality of fluid chambers spaced apart in the circumferential direction, and orifice passages are provided to communicate the plurality of fluid chambers, A magnetic functional fluid is sealed in the fluid chamber, a magnetic field generating unit that applies a magnetic field to the magnetic functional fluid flowing through the orifice passage is provided outside the fluid chamber; the outer cylindrical member is made of a non-magnetic material, the intermediate cylindrical member is made of a ferromagnetic material, The intermediate cylindrical member has a magnetic field action opening at a position corresponding to the orifice passage through which a magnetic field is applied to the magnetic functional fluid.

[0012] In the vibration-damping device according to this aspect, the fluid sealed in the fluid chamber is a magnetic functional fluid, and its viscosity changes depending on the magnetic field applied by the magnetic field generating unit. Therefore, by controlling the magnetic field applied by the magnetic field generating unit in response to, for example, input vibrations, the characteristics of the vibration-damping device can be changed, thereby achieving good vibration-damping performance.

[0013] In particular, in this type of vibration-damping device, the outer cylindrical member arranged to cover the outer periphery of the fluid chamber is made of a non-magnetic material, so that the magnetic field from the magnetic field generating unit is prevented from being blocked or reduced by the outer cylindrical member, and the magnetic field from the magnetic field generating unit can be effectively exerted on the magnetic functional fluid.

[0014] Furthermore, in this vibration-damping device, an intermediate cylindrical member made of a ferromagnetic material is used, and a magnetic field action opening is provided in the intermediate cylindrical member at a position corresponding to the orifice passage, so that the magnetic field from the magnetic field generating unit can be efficiently guided to the orifice passage through the intermediate cylindrical member. That is, for example, the magnetic field from the magnetic field generating unit can be efficiently guided to the vicinity of the orifice passage through the intermediate cylindrical member, and the guided magnetic field can be directed from the intermediate cylindrical member toward the orifice passage by the magnetic field action opening. Furthermore, even if a magnetic flux concentration member (described later) or the like is provided to improve magnetic flux concentration at the location where the orifice passage is formed, the magnetic field action opening prevents or reduces the escape of concentrated magnetic flux through the intermediate cylindrical member, which is advantageous for magnetic flux concentration in the orifice passage.

[0015] In this way, in this type of vibration-damping device, by cleverly utilizing the intermediate cylindrical member to secure the outer cylindrical member to the outer peripheral surface of the main rubber elastic body and ensure the liquid-tightness of the fluid chamber, it is possible to efficiently act the magnetic flux from the magnetic field generating unit on the magnetic functional fluid in the orifice passage, and as a result, a new vibration-damping device can be realized that can switch vibration-damping characteristics with good energy efficiency.

[0016] A second aspect of the present invention is the vibration isolation device according to the first aspect, The intermediate cylindrical member is a pair of axially opposite portions each having a large-diameter cylindrical shape that is continuous in the circumferential direction; a groove-shaped axial intermediate portion that is partially provided in the circumferential direction and extends circumferentially between the pair of axial side portions, The magnetic field action opening is provided in the axially intermediate portion.

[0017] In the vibration-damping device of this embodiment, the groove-shaped axial middle portion of the intermediate cylindrical member is utilized to form an orifice passage in the groove-shaped internal space, and deformation of the orifice passage caused by, for example, deformation of the main rubber elastic body due to input vibrations can also be suppressed by the axial middle portion of the intermediate cylindrical member.

[0018] A third aspect of the present invention is the vibration isolation device according to the second aspect, the intermediate cylindrical member is a single member in which the pair of axially opposite portions are connected at the axially intermediate portion, The magnetic field action opening is constituted by a window portion formed through the bottom of the groove in the axially intermediate portion of the groove.

[0019] In the vibration-damping device of this embodiment, a magnetic field action opening is provided in the intermediate cylindrical member, while the entire intermediate cylindrical member can be made into a single member, which makes it possible to manage the members and simplify the manufacture of the vibration-damping device.

[0020] A fourth aspect of the present invention is the vibration isolation device according to the second aspect, the intermediate cylindrical member has a structure in which it is divided into axially opposite sides at the axially intermediate portion, and the pair of axially opposite sides are separate members, The magnetic field action opening is formed between the divided portions spaced apart in the axial direction of the axially intermediate portion.

[0021] In the vibration damping device according to this aspect, the intermediate cylindrical member is separated from the other on both axial sides by the magnetic field action opening, and therefore the intermediate cylindrical member is essentially divided in the axial direction around the magnetic field action opening as well. Therefore, for example, it is possible to prevent the magnetic flux acting on the orifice passage from escaping due to the magnetic path being formed by a continuous portion of the intermediate cylindrical member around the magnetic field action opening.

[0022] A fifth aspect of the present invention is the vibration isolation device according to any one of the first to fourth aspects, The magnetic field generating unit is disposed on the outer circumferential side of the outer cylindrical member.

[0023] In the vibration-damping device according to this aspect, the arrangement space for the magnetic field generating unit can be set with a relatively large degree of freedom on the outer circumferential side of the outer cylindrical member while avoiding any influence on the fluid chamber, the main rubber elastic body, etc. In particular, in this aspect, by making the outer cylindrical member out of a non-magnetic material, it is possible to efficiently apply the magnetic field from the magnetic field generating unit arranged on the outer circumferential side of the outer cylindrical member to the orifice passage, for example, by forming the orifice passage to extend along the inner circumferential surface of the outer cylindrical member.

[0024] A sixth aspect of the present invention is the vibration isolation device according to any one of the first to fifth aspects, In the orifice passage, magnetic flux concentrating members made of ferromagnetic material are arranged opposite each other in the width direction of the orifice passage, and the magnetic field action opening in the intermediate cylindrical member is provided at a position corresponding to the space between the opposing portions of the magnetic flux concentrating members.

[0025] In the vibration damping device according to this aspect, by disposing the magnetic flux concentrating member at the location where the orifice passage is formed, it is possible to further concentrate the magnetic flux acting on the orifice passage.

[0026] A seventh aspect of the present invention is the vibration isolation device according to the sixth aspect, The intermediate Cylinder and the outer cylindrical member, an orifice member for forming the orifice passage is disposed so as to extend in the circumferential direction through an opening of the pocket-shaped portion provided in the main rubber elastic body, the orifice member is a ferromagnetic material; The magnetic flux concentrating members arranged opposite to each other in the width direction of the orifice passage are constituted by the orifice members.

[0027] In the vibration damping device according to this aspect, the orifice member extending to the opening of the pocket-shaped portion allows for a large degree of freedom in designing the length of the orifice passage, etc. Furthermore, by utilizing the orifice member, it becomes possible to efficiently apply magnetic flux to the magnetic functional fluid in the orifice passage.

[0028] An eighth aspect of the present invention is the vibration isolation device according to any one of the first to seventh aspects, The magnetic field generating unit comprises: a coil member that generates a magnetic field when energized; a yoke member that guides magnetic flux in the magnetic field generated by the coil member to the orifice passage; It includes the following.

[0029] In the vibration-damping device of this embodiment, it is possible to efficiently guide the magnetic flux from the magnetic field-generating coil member to the magnetic functional fluid in the orifice passage via the yoke member, and by controlling the current flowing through the coil member, it is also possible to easily control the magnetic flux density acting on the magnetic functional fluid and, therefore, the vibration-damping characteristics exhibited.

[0030] In this aspect, the yoke member may be partially or entirely made of an intermediate sleeve, or may be made of the magnetic flux concentrating member described in the sixth or seventh aspect, thereby enabling the yoke member to be constructed with a reduced number of parts and a simple structure. [Effects of the Invention]

[0031] According to the present invention, in an anti-vibration device in which the vibration-damping characteristics can be changed by controlling the magnetic field applied to the magnetorheological fluid sealed in the fluid chamber from a magnetic field generating unit provided outside the fluid chamber, the magnetic field from the magnetic field generating unit can be made to act efficiently on the magnetorheological fluid sealed in the fluid chamber, thereby realizing an anti-vibration device with a novel structure that can switch vibration-damping characteristics with good energy efficiency. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 3 is a cross-sectional view showing an engine mount according to a first embodiment of the present invention, which corresponds to cross section II of FIG. [Figure 2] II-II cross section of Figure 1 [Figure 3] FIG. 2 is a perspective view of a mount body that constitutes the engine mount shown in FIG. 1, with the outer cylindrical member removed; [Figure 4] 2A, 2B, and 2C are diagrams showing an intermediate sleeve constituting the engine mount shown in FIG. 1, in which (a) is a perspective view, (b) is a front view, and (c) is a vertical cross-sectional view. [Figure 5] FIG. 7 is a cross-sectional view showing an engine mount according to a second embodiment of the present invention, corresponding to the cross section IV-IV of FIG. [Figure 6] VI-VI cross section of Figure 5 [Figure 7] FIG. 6 is a perspective view of a mount body that constitutes the engine mount shown in FIG. 5, with the outer cylindrical member removed. [Figure 8] FIG. 6 is a plan view of an orifice member that constitutes the engine mount shown in FIG. 5. [Figure 9] FIG. 10 is a cross-sectional view showing an engine mount according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a plan view of an orifice member that constitutes the engine mount shown in FIG. [Figure 11] FIG. 10 is a cross-sectional view showing a portion of an engine mount according to a fourth embodiment of the present invention. [Figure 12] 1A to 1C are diagrams illustrating another example of an intermediate sleeve that can be used in the first to fourth embodiments of the present invention, in which (a) is a perspective view, (b) is a front view, and (c) is a vertical cross-sectional view. [Figure 13] 10A to 10C are diagrams illustrating another example of an intermediate sleeve that can be used in the first to fourth embodiments of the present invention, in which (a) is a perspective view, (b) is a front view, and (c) is a vertical cross-sectional view. [Figure 14] 10A to 10C are diagrams illustrating another example of an intermediate sleeve that can be used in the first to fourth embodiments of the present invention, in which (a) is a perspective view, (b) is a front view, and (c) is a vertical cross-sectional view. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0034] Figures 1 and 2 show an automotive engine mount 10 as a first embodiment of a vibration-damping device constructed in accordance with the present invention. Engine mount 10 is a fluid-filled vibration-damping device and has a mount body 12 in which an inner axial member 14 and an outer tubular member 16 are connected by a main rubber elastic body 18, and Figure 3 shows mount body 12 without outer tubular member 16. In the following description, as a general rule, the axial direction refers to the left-right direction in Figure 1, which is the direction of the mount's central axis, and the up-down direction refers to the up-down direction in Figure 2, which is the main vibration input direction.

[0035] The inner shaft member 14 has a small diameter, generally cylindrical shape, and extends linearly in the axial direction. The material of the inner shaft member 14 is not particularly limited, and a ferromagnetic material such as an iron-based metal can be used. However, if there is a concern that the inner shaft member 14 may be adversely affected by the magnetic field generated by the magnetic field generating unit (56), which will be described later, it is preferable that the inner shaft member 14 be made of a non-magnetic material such as stainless steel or an aluminum alloy.

[0036] A stopper member 20 is fixed to the axial center portion of the inner shaft member 14. The stopper member 20 is generally annular in shape and is fixedly attached to the inner shaft member 14 in an externally inserted state. As shown in FIG. 2, the inner shaft member 14 has two protrusions 22, 22 that protrude outward in the vertical direction. Note that the stopper member 20 is not essential, but if the stopper member 20 is used and there is concern about adverse effects on the magnetic field from the magnetic field generating unit (56), which will be described later, it is desirable to form the stopper member from a non-magnetic material such as synthetic resin, rubber elastic body, or aluminum alloy.

[0037] An intermediate sleeve 24 serving as an intermediate cylindrical member is disposed around the inner axial member 14. As shown in the single-item view of Fig. 4, the intermediate sleeve 24 has a generally cylindrical shape with a larger diameter than the inner axial member 14, and is disposed in an externally inserted state spaced apart from the inner axial member 14 in the radial direction. Note that the inner axial member 14 and the intermediate sleeve 24 (and the outer cylindrical member 16) may be eccentric in the radial direction, but in this embodiment they are disposed on approximately the same central axis.

[0038] The intermediate sleeve 24 is made of a ferromagnetic material, such as an iron-based metal, which can reduce manufacturing costs and simplify processing while maintaining the strength of the intermediate sleeve 24, as compared to using a non-magnetic material such as an aluminum alloy.

[0039] The intermediate sleeve 24 has window portions 26, 26 at two locations in the circumferential direction, and in this embodiment, the pair of window portions 26, 26 are positioned opposite each other in the vertical direction (the vertical direction in FIG. 1 ). Each window portion 26 penetrates the intermediate sleeve 24 in the thickness direction at the axial center of the intermediate sleeve 24, and has a generally rectangular shape that extends circumferentially with a predetermined width in the axial direction.

[0040] A groove portion 28 extending in the circumferential direction is provided between the two window portions 26, 26 in the intermediate sleeve 24, and is positioned opposite to each other in the left-right direction in Fig. 2. Each groove portion 28 is a recessed groove-shaped portion that has a small diameter in the axially middle portion of the intermediate sleeve 24 and opens to the outer circumferential surface, extends in the circumferential direction of the intermediate sleeve 24, and both circumferential ends reach one of the two window portions 26, 26.

[0041] In short, the intermediate sleeve 24 has a pair of axially opposite portions 29, 29 that are circumferentially continuous and have a large-diameter cylindrical shape, and the axially intermediate portion has integral groove-like portions 28, 28 that are partially provided in the circumferential direction and extend circumferentially between and connect the pair of axially opposite portions 29, 29.

[0042] Furthermore, in the intermediate sleeve 24, a magnetic field action opening 32 is formed in the form of a through-hole penetrating from the inside to the outside in the bottom wall portion 30 of each groove-like portion 28 constituting the axially intermediate portion. In this embodiment, the magnetic field action opening 32 is formed in a substantially rectangular shape in the central portion of the bottom wall portion 30 so that the bottom wall portion 30 of each groove-like portion 28 remains in the shape of a surrounding rectangular frame.

[0043] The inner shaft member 14 and intermediate sleeve 24 are connected by a main rubber elastic body 18. The main rubber elastic body 18 has a thick, generally cylindrical shape, and its inner peripheral portion is fixed to the inner shaft member 14 and its outer peripheral portion is fixed to the intermediate sleeve 24. The main rubber elastic body 18 also extends through the magnetic field action opening 32 of the intermediate sleeve 24 to the inner surface of the groove-shaped portion 28, and is also fixed to the outer peripheral surface of the intermediate sleeve 24 in the groove-shaped portion 28. This main rubber elastic body 18 can be formed as an integrally vulcanization-molded product comprising the inner shaft member 14 and the intermediate sleeve 24.

[0044] 2, the main rubber elastic body 18 is provided with two pocket-like portions 34. Each of the pocket-like portions 34 is a depression or recess that opens onto the outer peripheral surface of the main rubber elastic body 18, and in this embodiment, opens in one of the vertical directions. The pair of pocket-like portions 34 is provided at positions corresponding to the pair of window portions 26 of the intermediate sleeve 24, and the peripheral edges of the openings of the pocket-like portions 34 are fixed to the opening frames of the window portions 26, so that each pocket-like portion 34 opens outward through the corresponding window portion 26. Furthermore, protrusions 22 of the stopper member 20 protrude from approximately the center of the bottom of each of the pocket-like portions 34, at a height approximately midway in the depth direction of the pocket-like portions 34.

[0045] Furthermore, an outer cylindrical member 16 is fitted onto the integrally vulcanization-molded main rubber elastic body 18, and this outer cylindrical member 16 is fitted onto and fixed to the outside of the intermediate sleeve 24. The outer cylindrical member 16 has a generally cylindrical shape with a larger diameter than the inner shaft member 14. The outer cylindrical member 16 is made of a non-magnetic material, and may be made of, for example, stainless steel, aluminum alloy, or the like.

[0046] In this embodiment, the entire inner peripheral surface of the outer cylindrical member 16 is covered with a thin seal rubber layer 36. The outer cylindrical member 16 is fitted and fixed to the intermediate sleeve 24 by a diameter-reducing process such as eight-way drawing. The seal rubber layer 36 sandwiched between the outer cylindrical member 16 and the intermediate sleeve 24 provides a fluid-tight seal.

[0047] In this way, the mount body 12 is formed by fitting the outer tubular member 16 to the outer surface of the integrally vulcanized molded product of the main rubber elastic body 18 including the inner shaft member 14 and the intermediate sleeve 24, and a fluid-sealed area that is fluid-tightly separated from the external space is formed inside the mount body 12.

[0048] This fluid-sealed region includes two fluid chambers 38, 38 formed by covering a pair of pocket-like portions 34, 34 of the main rubber elastic body 18 with the outer cylindrical member 16. These fluid chambers 38, 38 are spaced apart from each other in the circumferential direction, and in this embodiment, a pair of fluid chambers 38, 38 are arranged on both sides in the vertical direction, sandwiching the inner shaft member 14 therebetween.

[0049] The partition wall between the two fluid chambers 38, 38 in the circumferential direction and the walls on both axial sides of each fluid chamber 38 are both formed by the main rubber elastic body 18. When vibration is input in the up-and-down direction in FIG. 1 , the inner shaft member 14 and the outer cylindrical member 16 are displaced relative to each other in the direction perpendicular to the axis, causing the main rubber elastic body 18 to elastically deform, resulting in relative pressure fluctuations between the two fluid chambers 38, 38. Furthermore, each fluid chamber 38 has a protrusion 22 of a stopper member 20 that protrudes from the radial inside to the radial outside, with the tip surface of the protrusion 22 facing the outer cylindrical member 16 at a predetermined distance. A stopper mechanism is formed by the abutment of each protrusion 22 with the outer cylindrical member 16, which limits the amount of elastic deformation of the main rubber elastic body 18 when vibration is input.

[0050] A magnetic functional fluid 39 is sealed in the fluid-sealed region including the pair of fluid chambers 38, 38. The magnetic functional fluid 39 may be any fluid whose viscosity changes in response to the action of a magnetic field. The magnetic functional fluid 39 may be, for example, a magnetorheological fluid (MRF), a magnetic fluid (MF), or a magnetic composite fluid (MCF) that is a mixture of a magnetorheological fluid and a magnetic fluid. The magnetic functional fluid 39 is preferably one whose viscosity changes significantly in response to changes in the magnetic flux density of the applied magnetic field, but a magnetic composite fluid, whose viscosity increase range can be easily adjusted by changing the mixing ratio of the magnetorheological fluid and the magnetic fluid, may also be used.

[0051] The magnetic functional fluid 39 may be a suspension or colloidal solution in which ferromagnetic particles are dispersed in a base liquid such as water or oil, and the surfaces of the ferromagnetic particles may be coated with a surfactant to prevent aggregation or sedimentation of the ferromagnetic particles in the base liquid. Alternatively, it is preferable that the ferromagnetic particles are dispersed in a base liquid to which a surfactant has been added, thereby preventing or reducing aggregation.

[0052] The ferromagnetic microparticles are, for example, metal particles such as iron, ferrite, and magnetite, and preferably have a particle diameter of approximately 8 nm to 10 μm. The base liquid is not particularly limited as long as it can disperse ferromagnetic microparticles, but examples of suitable liquids include water, isoparaffin, alkylnaphthalene, perfluoropolyether, polyolefin, and silicone oil. The base liquid is preferably an incompressible fluid. The surfactant is appropriately selected depending on the base liquid, and oleic acid is preferably used, for example. The difference between magnetorheological fluids and magnetic fluids is primarily the particle diameter of the ferromagnetic microparticles, with magnetorheological fluids having larger particle diameters than magnetic fluids.

[0053] However, as mentioned above, the above description of the magnetic functional fluid lists preferred examples of the magnetic functional fluid 39, and such description should not be interpreted in a limiting manner to the magnetic functional fluids that can be used in the present invention.

[0054] The fluid chambers 38, 38 containing such magnetic functional fluid 39 are connected to each other by orifice passages 40, 40 which form fluid-containing regions similar to the fluid chambers 38, 38. Each orifice passage 40 extends circumferentially from both circumferential ends of each fluid chamber 38, connecting the pair of fluid chambers 38, 38 to each other.

[0055] In this embodiment, in the pair of groove-like portions 28, 28 of the intermediate sleeve 24, an orifice groove 41 is formed in the main rubber elastic body 18 filled in each groove-like portion 28, and the orifice groove 41 is covered with the outer cylindrical member 16 to form an orifice passage 40. The orifice groove 41 extends in each groove-like portion 28 of the intermediate sleeve 24 over the entire circumferential length with a substantially constant cross-sectional shape.

[0056] Each orifice groove 41 is fitted with a magnetic flux concentrator 42 made of a ferromagnetic material such as iron. In this embodiment, a pair of magnetic flux concentrator members 42 is incorporated into both ends of the orifice groove 41 in the groove width direction (mount axial direction). The pair of magnetic flux concentrator members 42 extends circumferentially in an arc shape with a substantially constant rectangular cross section. They are fitted into both sides of the orifice groove 41 in the groove width direction, and are positioned and fixed within the orifice groove 41 by having their outer peripheral surfaces pressed by the outer cylindrical member 16. As a result, the magnetic flux concentrator members 42 are arranged in a filled state over the entire length of both sides of the orifice groove 41 in the groove width direction, and an orifice passage 40 that allows fluid to flow between the pair of fluid chambers 38 is formed between the opposing surfaces of the pair of magnetic flux concentrator members 42.

[0057] In this embodiment, a positioning protrusion 44, which is located at the center of the orifice groove 41 in the groove width direction, protrudes from the groove bottom surface, and extends in the circumferential direction, is formed by the main rubber elastic body 18 that is wound into the orifice groove 41 of the intermediate sleeve 24. This positioning protrusion 44 fits between the opposing surfaces of the pair of magnetic flux concentrating members 42, 42, so that the dimension between the opposing surfaces of the pair of magnetic flux concentrating members 42, 42, and therefore the flow path cross-sectional area of ​​the orifice passage 40, is set with high accuracy and stability. The magnetic flux concentrating members 42, 42 may be positioned by being connected to each other with a non-magnetic material or by being adhered to the rubber elastic body, and the positioning protrusion 44 is not essential.

[0058] Furthermore, a cylindrical cover member 46 is attached in an externally inserted state to the mount main body 12, and the outer cylindrical member 16 and the cylindrical cover member 46 form a housing for the magnetic field generating unit. The cylindrical cover member 46 has a generally cylindrical shape with a larger diameter than the outer cylindrical member 16, and is not limited to any particular material, with a metal material having high strength and rigidity being preferably used.

[0059] A magnetic field generating unit 56 is assembled between the outer cylindrical member 16 and the cylindrical cover member 46, which are positioned relative to each other in the axial and radial directions, while being positioned by the supporting elastic bodies 52, 54.

[0060] The magnetic field generating unit 56 has a generally annular shape and is configured with a yoke member 60 assembled around a coil 58. The coil 58 generates a magnetic field when current is applied, and a conventionally known coil may be used. Generally, the coil 58 has a winding structure in which an insulatingly coated current-carrying wire is wound around a bobbin, and the entire coil is coated with an insulating resin as needed. In this embodiment, for example, a large-diameter air-core coil structure in which the current-carrying wire is wound circumferentially around the outer peripheral surface of the outer tubular member 16 may be used. Both ends of the current-carrying wire of the coil 58 are axially extracted at one circumferential location and are electrically connected to a terminal portion 66 of a connector 64, so that the coil 58 is electrically connected to an external current-carrying control device (not shown) via the connector 64.

[0061] The yoke member 60 is made of a ferromagnetic material such as iron. The yoke member 60 has a U-shaped cross section that opens toward the inner periphery, and is disposed so as to cover both axial end faces and the outer periphery of the coil 58. The open end face on the inner periphery side of the yoke member 60 is assembled in abutting or close proximity to the outer periphery of the outer cylindrical member 16. The both axial end faces and the outer periphery of the yoke member 60 are positioned and fixedly supported by the magnetic field generating unit housing, which is made up of the outer cylindrical member 16 and the cylindrical cover member 46, via elastic support bodies 52, 54.

[0062] As a result, magnetic flux generated by energizing coil 58 is guided by yoke member 60, which is a ferromagnetic material, preventing leakage of magnetic flux axially outward or radially outward. The magnetic flux guided by yoke member 60 is released to the outside of yoke member 60 from both axially open ends on the inner circumferential side of yoke member 60. However, magnetic flux concentrating members 42, 42 made of a ferromagnetic material and intermediate sleeve 24 are disposed relatively close to the inner circumferential side of yoke member 60, via outer cylindrical member 16 and seal rubber layer 36 made of a nonmagnetic material. Therefore, magnetic flux generated by energizing coil 58 is guided from the inner circumferential side of yoke member 60 into magnetic flux concentrating members 42, 42 and intermediate sleeve 24, forming a magnetic path on the inner circumferential side of coil 58.

[0063] The magnetic flux concentrating members 42, 42 that form this magnetic path are divided by the orifice passage 40, and the axially opposing surfaces of the pair of magnetic flux concentrating members 42, 42 form magnetic pole faces that face each other across the orifice passage 40 on the magnetic path. The magnetic path is also divided in the intermediate sleeve 24 by the magnetic field action opening 32 at a position corresponding to the orifice passage 40. This prevents magnetic poles acting on the axially opposing surfaces (magnetic pole faces) of the magnetic flux concentrating members 42, 42 from escaping to the intermediate sleeve 24. Furthermore, even if there is magnetic flux guided from the yoke member 60 to the intermediate sleeve 24, the magnetic path resistance on the intermediate sleeve 24 is increased by the magnetic field action opening 32, making it easier for the magnetic flux to be guided to the magnetic flux concentrating members 42, 42. As a result, the magnetic flux density between the axially opposing surfaces of the magnetic flux concentrating members 42, 42 that form magnetic pole faces that face each other across the orifice passage 40 can be improved.

[0064] Furthermore, the intermediate sleeve 24 has cylindrical axial side portions 29, 29, and the groove-like portion 28 is formed integrally with these axial side portions 29, 29. Therefore, the magnetic flux emitted from the open ends on both axial sides of the yoke member 60 over the entire circumferential direction can also be captured by the axial side portions 29, 29 and guided from the groove-like portion 28 to the orifice passage 40 between the opposing surfaces of the magnetic flux concentration members 42, 42, making it possible to more efficiently apply magnetic force to the magnetic functional fluid 39.

[0065] Thus, in the engine mount 10 of this embodiment, the magnetic flux generated by energizing the coil 58 is concentrated on the orifice passage 40, and a large magnetic force can be exerted on the magnetic functional fluid 39 flowing through the orifice passage 40. In short, it is possible to efficiently obtain magnetic energy that is exerted on the magnetic functional fluid 39 in the orifice passage 40 in response to the energy supplied to the magnetic field generating unit 56.

[0066] The specific shape of the orifice passage 40, such as the passage cross-sectional area and length, is not limited and may be appropriately tuned so as to exhibit fluid flow characteristics corresponding to the required vibration damping performance.

[0067] Furthermore, by forming the orifice passage 40 between the opposing surfaces of the magnetic flux concentration members 42, 42 over the entire length as shown in this embodiment, it is possible to increase the magnetic force acting on the magnetic functional fluid 39 in the orifice passage 40, but this is not limitative. For example, the magnetic flux concentration members 42, 42 may be disposed partially in the length direction of the orifice passage 40. Furthermore, in addition to forming the entire surfaces of the pair of opposing surfaces in the passage cross section of the orifice passage 40 with the magnetic flux concentration members 42, 42, the pair of opposing surfaces in the passage cross section of the orifice passage 40 may also be formed partially with the magnetic flux concentration members 42, 42.

[0068] It is desirable that the axially outer end of each magnetic flux concentrator 42 be closer to the inner opening end of the corresponding yoke member 60 in the axial direction from the viewpoints of concentrating magnetic flux and reducing magnetic resistance in the magnetic path. For example, each magnetic flux concentrator 42 may be configured so that it at least partially overlaps with the inner opening end of the yoke member 60 in radial projection. In this embodiment, the axially outer end of each magnetic flux concentrator 42 is spaced axially inward from the inner opening end of the yoke member 60 so that the two components do not overlap in radial projection. However, it is desirable to make this axial separation amount D small, and preferably satisfy the relationship D≦(2 / 3)B, where B is the width of the inner opening of the yoke member 60.

[0069] In addition, the opposing surfaces between the magnetic flux concentrating members 42, 42 and the magnetic field action opening 32 of the intermediate sleeve 24 can also be considered to be approximately the same in that they are arranged in the area of ​​action of the magnetic field generated by the magnetic field generating unit 56 and have a magnetic gap-shaped magnetic path dividing portion at a position corresponding to the orifice passage 40, thereby improving the magnetic field action on the magnetic functional fluid 39 in the orifice passage 40.

[0070] Therefore, the magnetic field action opening 32 of the intermediate sleeve 24 is located on the inner circumferential side of the orifice passage and is formed at a position corresponding to the orifice passage so as to overlap the orifice passage when projected in the radial direction. The size and shape of the magnetic field action opening 32 are not particularly limited, but considering the rate of increase in magnetic flux acting on the orifice passage 40, it is desirable that the axial width of the magnetic field action opening 32 be equal to or greater than the passage width of the orifice passage 40. In particular, in this embodiment in which the orifice passage 40 is formed between the opposing surfaces of a pair of magnetic flux concentration members 42, 42, it is desirable that the axial width of the magnetic field action opening 32 be set greater than the distance between the opposing surfaces of the pair of magnetic flux concentration members 42, 42, in consideration of the concentration of magnetic flux on the magnetic flux concentration members 42, 42.

[0071] Furthermore, considering the rate of increase of the magnetic flux acting on the orifice passage 40, it is desirable that the magnetic field action opening 32 be formed to have a length spanning the entire length of the orifice passage 40 in the passage length direction of the orifice passage 40 (in the mount circumferential direction in this embodiment). However, the magnetic field action opening 32 does not necessarily have to span the entire length of the orifice passage, and may be located partially, and is preferably provided over more than half the length of the orifice passage in the length direction, more preferably over 60% or more, and even more preferably over 80% or more. Incidentally, in this embodiment, the magnetic field action opening 32 is provided in the central portion of the orifice passage excluding both end portions, over a length that is approximately 80% of the entire length of the orifice passage.

[0072] At both axial end portions of the magnetic field action opening 32, the intermediate sleeve 24 overlaps, in radial projection, each opening end on the inner periphery of the yoke member 60. In particular, in this embodiment, at least a portion (the axial inner end portions) of the large-diameter axial end portions 29, 29 of the intermediate sleeve 24 overlaps, in radial projection, each opening end on the inner periphery of the yoke member 60. This also reduces leakage magnetic flux that escapes from the yoke member 60 and escapes from the closed set magnetic path (the magnetic path passing through the magnetic flux concentration members 42, 42, the intermediate sleeve 24, and the orifice passage 40) to the outside.

[0073] The engine mount 10 of this embodiment having the above-described structure is mounted to a vehicle, for example, by attaching the inner axial member 14 to a power unit 68, which is one of the members in the vibration-damping connection, and by attaching the tubular cover member 46 fixed to the outer tubular member 16 to a vehicle body 70, which is the other member in the vibration-damping connection. The tubular cover member 46 is fixed to the vehicle body 70, for example, by being press-fitted into a mounting hole 72 in the vehicle body 70. The inner axial member 14 may be attached to the power unit 68 via an inner bracket (not shown). Similarly, the tubular cover member 46 may be attached to the vehicle body 70 via an outer bracket (not shown).

[0074] When engine mount 10 is mounted on a vehicle in this manner, and vertical vibrations are input to engine mount 10 with fluid chambers 38, 38 arranged opposite each other, a flow of the enclosed fluid (magnetic functional fluid 39) occurs between fluid chambers 38, 38 through orifice passage 40, and a vibration-damping effect is achieved based on the flow action of the fluid.

[0075] In the engine mount 10, the magnetic field generated by the magnetic field generating unit 56 is controlled by energizing the coil 58, thereby controlling the viscosity of the magnetic functional fluid 39. In particular, the magnetic field generated by the magnetic field generating unit 56 is generated around the coil 58 by energizing the coil 58, and is then applied to the inside of the mount body 12 through the yoke member 60. As described above, the magnetic flux concentrating members 42, 42 disposed at positions corresponding to the orifice passage 40 and the intermediate sleeve 24 having the magnetic field action opening 32 act efficiently and intensively on the magnetic functional fluid 39 in the orifice passage 40.

[0076] Since the viscosity of the magnetic functional fluid 39 changes depending on the strength of the applied magnetic field, it is possible to control the viscosity of the magnetic functional fluid 39 in the orifice passage 40 by, for example, turning on / off the power supply to the coil 58 or adjusting the amount of power supply in a stepwise or continuous manner, thereby controlling the flow characteristics of the magnetic functional fluid 39 through the orifice passage 40, thereby switching and controlling the performance (vibration damping characteristics) of the engine mount 10. The manner in which the performance of the engine mount 10 can be switched is not particularly limited, and the performance can be switched in two or more modes in a stepwise or continuously non-stepwise manner so as to meet the required vibration damping performance.

[0077] In particular, in this embodiment, as described above, it is possible to efficiently obtain the magnetic energy that is exerted on the magnetic functional fluid 39 in the orifice passage 40 in response to the power energy supplied to the magnetic field generating unit 56, making it easy to realize large characteristic changes with excellent energy efficiency when controlling the switching of the vibration damping characteristics of the engine mount 10.

[0078] Furthermore, in the engine mount 10 of this embodiment, the magnetic field generating unit 56 is arranged outside the fluid-enclosed area on the outer periphery of the outer cylindrical member 16, and is a separate structure from the mount main body 12. This simplifies the structure including the magnetic field generating unit 56, and the current-carrying structure for the magnetic field generating unit 56 can also be formed independently from the mount main body 12, facilitating manufacturing and management.

[0079] 5 and 6 show an engine mount 80 for an automobile as a second embodiment of a fluid-filled type vibration damping device constructed in accordance with the present invention. Engine mount 80 of this embodiment exemplifies one aspect that differs from the first embodiment in terms of the structure of the orifice passage and the passage length of the orifice passage, and components and parts that are substantially the same as those in the first embodiment are given the same reference numerals in the drawings as in the first embodiment, and description thereof will be omitted.

[0080] As can be seen from Figure 7, which shows the mount body 12 excluding the outer cylindrical member 16, the engine mount 80 of this embodiment is equipped with a pair of orifice members 82, 82 that are combined in series in the circumferential direction to form a single circumferentially long orifice passage 81, and this pair of orifice members 82, 82 is used in place of the pairs of magnetic flux concentration members 42, 42 in the engine mount 10 of the first embodiment.

[0081] That is, each orifice member 82 is made of the same material (ferromagnetic material) as the magnetic flux concentrating member of the first embodiment, and has a generally semi-cylindrical shape with a circumferential length slightly less than halfway around the circumference as a whole. The pair of orifice members 82, 82 are butted together at one circumferential end, and are assembled to the integrally vulcanization-molded main rubber elastic body 18 in a state where their outer circumferential portions extend a length slightly less than one circumference.

[0082] In this assembled state, one circumferential end of the pair of orifice members 82, 82 that are butted against each other is fitted into the groove portion 28 of one of the intermediate sleeves 24 (the right side in FIG. 6). The other circumferential end of the pair of orifice members 82, 82 is both fitted into the circumferential end of the groove portion 28 of the other of the intermediate sleeves 24 (the left side in FIG. 6). A partition rubber 84 is formed in the circumferential middle portion of the other groove portion 28 of the intermediate sleeve 24, protruding over the entire length in the groove width direction. The other circumferential end of the pair of orifice members 82, 82 is positioned on both sides of the partition rubber 84 in the circumferential direction, so that one circumferential end of the pair of orifice members 82, 82 is held in an butted state.

[0083] As shown in FIG. 8, each orifice member 82 is provided with wide protrusions 86, 86 that protrude in a width dimension (dimension in the mount axial direction) at the circumferential middle portion, and the circumferential middle portion is larger than both circumferential side portions.

[0084] Each orifice member 82 has a continuous hole 88 formed therein, which extends continuously in the circumferential direction from one circumferential end thereof to near the other circumferential end thereof, penetrating from the inside to the outside. Furthermore, a wide, generally rectangular through-hole 90 is formed at the other circumferential end of the orifice member 82, penetrating the inner and outer surfaces, with the terminal end of the continuous hole 88 opening into the through-hole 90. Furthermore, a bottom member 92 made of a non-magnetic material such as rubber elastic body or synthetic resin is fixed to the inner circumferential opening of the continuous hole 88, thereby sealing it fluid-tightly, so that the continuous hole 88 essentially has a recessed groove structure.

[0085] In this embodiment, a pair of such orifice members 82, 82 are fitted into and assembled to the groove portions 28, 28 of the intermediate sleeve 24, instead of the magnetic flux concentrating members 42, 42 in the first embodiment. As a result, the continuous holes 88, 88 of the pair of orifice members 82, 82 are connected in series in the circumferential direction, forming a single orifice passage 81 that extends circumferentially around the inner circumferential surface of the outer cylindrical member 16 for a length of at least halfway around the circumference. Note that both circumferential ends of the orifice passage 81 are in communication with one of the fluid chambers 38 via through holes 90 formed in each of the orifice members 82.

[0086] In the engine mount 80 of this embodiment, the orifice member 82, which is made up of a single component, is divided into two axially opposite sides (in the orifice width direction) by the continuous hole 88 at the portion where the orifice passage 81 is formed, thereby forming a pair of magnetic flux concentrating portions 94, 94 that are positioned facing each other a predetermined distance in the axial direction. The orifice passage 81 is formed between the facing surfaces of the pair of magnetic flux concentrating portions 94, 94 made of a ferromagnetic material.

[0087] Therefore, in the engine mount 80 of this embodiment, as in the engine mount of the first embodiment, it is possible to efficiently control the viscosity of the magnetic functional fluid 39 using the magnetic field from the magnetic field generating unit 56, and it is possible to achieve switching control of vibration-damping characteristics based on the fluid flow action through the orifice passage 81 with excellent energy efficiency.

[0088] In particular, in this embodiment, an orifice passage 81 having a longer passage length than the orifice passage 40 of the first embodiment is realized, which improves the degree of freedom in tuning the orifice passage 81, and also makes it possible to further change the vibration-damping characteristics by applying the magnetic field from the annular magnetic field generating unit 56 to the magnetic functional fluid 39 in the orifice passage 81 over a wide circumferential range.

[0089] In addition, in this embodiment, in the wide protrusions 86, 86 formed on the orifice member 82, a pair of magnetic flux concentration portions 94, 94 are arranged so as to overlap each opening end on the inner periphery of the yoke member 60 in radial projection, thereby suppressing leakage magnetic flux on the magnetic path, and making it possible to more efficiently apply the magnetic field from the yoke member 60 to the magnetic flux concentration portions 94, 94 and ultimately to the magnetic functional fluid 39 in the orifice passage 81.

[0090] In the orifice member 82 of this embodiment, the pair of magnetic flux concentrating portions 94, 94 separated by the continuous hole 88 are formed as a single component integrally connected to the outer periphery of the through hole 90 provided at one end in the circumferential direction, but for example, the pair of magnetic flux concentrating portions 94, 94 may be formed as separate components independent of each other and connected by the bottom member 92. In that case, there is no need to provide the through hole 90, and it is possible to avoid a decrease in the magnetic force acting on the magnetic functional fluid 39 in the orifice passage 82 due to magnetic flux detouring through the continuous portion of the outer periphery of the through hole 90.

[0091] Furthermore, the shapes of the surfaces on which magnetic force acts on the magnetic functional fluid in the orifice passage, i.e., the opposing surfaces of the pair of magnetic flux concentrating members 42, 42 in the first embodiment and the opposing surfaces of the pair of magnetic flux concentrating portions 94, 94 in the second embodiment, are not limited to parallel opposing flat surfaces as shown in the examples.

[0092] 9 and 10 show an engine mount 100 according to a third embodiment, in which non-parallel opposing surfaces can be used in a pair of magnetic flux concentrating portions 94, 94. In the engine mount 100 of this embodiment, members and parts having substantially the same structure as those in the second embodiment are denoted by the same reference numerals in the drawings as in the second embodiment, and detailed description thereof will be omitted.

[0093] That is, the orifice member 102 in the engine mount 100 of this embodiment has substantially the same structure as the orifice member 82 of the second embodiment, but the opposing surfaces 104, 104 of a pair of magnetic flux concentration sections 94, 94 that form both side wall surfaces of the orifice passage 81 have non-parallel opposing surfaces, and the shape of the cross section of the orifice passage 81 is other than rectangular.

[0094] In particular, in this embodiment, the opposing surfaces 104, 104 of the pair of magnetic flux concentration portions 94, 94 that form the side walls of the orifice passage 81 are inclined surfaces that gradually become more spaced apart from each other from the inner circumferential side toward the outer circumferential side, so that the cross-sectional shape of the orifice passage 81 is generally trapezoidal.

[0095] Incidentally, if the distance between the opposing surfaces 104, 104 of a pair of magnetic flux concentration portions 94, 94 is made larger on the outer periphery side than on the inner periphery side as in this embodiment, the magnetic flux exerted between the pair of opposing surfaces 104, 104 becomes more likely to be guided to the inner periphery side than the outer periphery side within the orifice passage 81, and a stronger magnetic field can be exerted on the magnetic functional fluid flowing on the inner periphery side within the orifice passage 112 than on the magnetic functional fluid flowing on the outer periphery side.

[0096] In this way, by varying the strength of the magnetic field applied to the magnetic functional fluid in the orifice passage 112 in the radial direction, it may be possible to control, for example, the flow state of the magnetic functional fluid in the orifice passage 112. Specifically, for example, if the viscosity of the magnetic functional fluid is made lower in the outer peripheral portion of the orifice passage 112, where the flow path of the magnetic functional fluid is longer, than in the inner peripheral portion, it is possible to expect an effect of suppressing the occurrence of turbulence due to differences in the flow path in the orifice passage 112.

[0097] However, the cross-sectional shape of the orifice passage 81 is not limited to the trapezoidal shape of this embodiment, and for example, only one of the passage wall surfaces in the opposing direction may be inclined, or the opposing surface 104 of the orifice passage 81 may be given any shape, such as a curved surface.

[0098] Furthermore, in the first to third embodiments, a single orifice passage 40, 81, 102 extending linearly in the circumferential direction is formed in the groove portion 28 of the intermediate sleeve 24, but the specific shape and structure of the orifice passage, including its length and cross-sectional area, are not limited. Also, as mentioned above, the magnetic flux concentrating member disposed in the orifice passage is not essential to the present invention, but the specific embodiment, including the shape and size of the magnetic flux concentrating member to be employed, is not limited.

[0099] For example, as shown in an engine mount 110 as a fourth embodiment in Figure 11, it is also possible to form two orifice passages 112, 112 extending substantially parallel to the orifice groove 41 formed in the groove-like portion 28 of the intermediate sleeve 24 and extending in the circumferential direction. Note that, since the engine mount 110 of this embodiment illustrates an aspect with respect to the orifice structure that is different from that of the first embodiment but has the same basic structure as that of the first embodiment, only a portion of a characteristic longitudinal cross section is shown, and in these drawings, members and parts that have substantially the same structure as those of the first embodiment are assigned the same reference numerals as those of the first embodiment, and detailed description thereof will be omitted.

[0100] That is, in the engine mount 110 of this embodiment, the magnetic flux concentrating member 114 serving as an orifice member forming the orifice passage 112 has a curved plate shape that extends in an arc in the circumferential direction with a substantially constant cross-sectional shape (substantially rectangular in this embodiment). The magnetic flux concentrating member 114 has substantially the same length in the circumferential direction as the orifice groove 41 formed in the groove-shaped portion 28 of the intermediate sleeve 24 and is disposed over the entire length of the orifice groove 41. The width dimension (dimension in the mount axial direction) of the magnetic flux concentrating member 114 is smaller than the groove width (groove inner dimension) of the orifice groove 41, and the magnetic flux concentrating member 114 is disposed at the widthwise center of the orifice groove 41. The thickness dimension (dimension in the mount radial direction) of the magnetic flux concentrating member 114 is the same as or slightly larger than the orifice groove 41.

[0101] As a result, the orifice groove 41 is partitioned in the groove width direction by the magnetic flux concentrating member 114, and a pair of orifice passages 112, 112 are formed located on both sides of the magnetic flux concentrating member 114 in the width direction and extending in the circumferential direction.

[0102] Of the two opposing wall surfaces of these paired orifice passages 112, 112 in the axial direction of the mount, only the wall surface located on the inner side in the axial direction of the mount is constructed of a magnetic flux concentration member 114, while the wall surface located on the outer side in the axial direction of the mount is constructed of the main rubber elastic body 18 within the groove-shaped portion 28.

[0103] In this way, even if only one wall surface of the orifice passage 112 in the passage width direction is formed by the magnetic flux concentrating member 114, the magnetic flux concentrating member 114 that forms the magnetic path of the magnetic field generated by the magnetic field generating unit 56 concentrates magnetic flux, and the end faces of the magnetic flux concentrating member 114 exposed to the orifice passages 112, 112 form magnetic pole faces, 116, 116. Therefore, magnetic force can be efficiently applied to the magnetic functional fluid 39 in each of the orifice passages 112, 112, and the same effect as in the above embodiment can be achieved.

[0104] In particular, in this embodiment, the intermediate sleeve 24 made of a ferromagnetic material is arranged axially outward of the orifice passage 112 in which the magnetic flux concentration member 114 is arranged axially inward of the mount. Therefore, the intermediate sleeve 24 also exerts a magnetic flux concentration effect on the magnetic functional fluid 39 in the orifice passage 112, and a synergistic magnetic flux concentration by the intermediate sleeve 24 and the magnetic flux concentration member 114 on the magnetic functional fluid 39 in the orifice passage 112 provided between the intermediate sleeve 24 and the magnetic flux concentration member 114 can also be expected.

[0105] In the engine mount 110 of this embodiment, in addition to the magnetic flux concentrating member 114 located in the axial center of the mount, magnetic flux concentrating members (42, 42) located at both ends in the axial direction of the mount as shown in the first embodiment may also be employed within the orifice groove 41, so that each of the opposing inner surfaces of the two orifice passages 112, 112 is constructed of a magnetic flux concentrating member.

[0106] Incidentally, in all of the first to fourth embodiments, the intermediate sleeve 24 is made of a single member formed by press molding or the like, but it is also possible to make the intermediate sleeve 24 have a divided structure consisting of two or more parts. By employing an intermediate sleeve 24 with a divided structure, it is possible to enjoy advantages in terms of manufacturing and assembly, and, for example, by dividing the intermediate sleeve at a position corresponding to the location where the orifice passage is formed and arranging the divided parts apart in the mount axial direction, it is also possible to suppress a decrease in the magnetic flux acting on the orifice passage due to the magnetic flux passing through the intermediate sleeve.

[0107] 12(a) to 12(c), the intermediate sleeve 24 may be configured as a pair of split sleeves 24a, 24a separated by a split line extending circumferentially through the axial center. In the drawings of other embodiments of the intermediate sleeve 24 shown below, the same reference numerals as in the above embodiment are used to designate the same components as in the above embodiment for ease of understanding.

[0108] In each split sleeve 24a, approximately half of the axial direction of the groove-shaped portion 28 is formed integrally with the large-diameter cylindrical axial side portions 29. The pair of split sleeves 24a, 24a are arranged on the outer peripheral surface of the main rubber elastic body, spaced a predetermined distance apart in the axial direction, with the end faces of the groove-shaped portions 28, 28 positioned axially opposite each other in the illustrated state.

[0109] In such split sleeves 24a, 24a, the same magnetic field action opening 32 as in the above embodiment may be formed so as to span between each bottom wall portion 30a, 30a, but in this embodiment, taking into consideration the strength, dimensional accuracy, and processing reasons of the split sleeves 24a, 24a, independent magnetic field action openings 32a, 32a are provided that penetrate approximately the center of each bottom wall portion 30a, 30a.

[0110] Even when a pair of split sleeves 24a, 24a split in the axial direction in this manner is used as the intermediate sleeve 24 of the above-described embodiments, the same effects as those of the above-described embodiments can be achieved. In particular, since the split sleeves 24a, 24a of this embodiment have both axial end portions spaced apart from each other, the escape (detour) of magnetic flux through the split sleeves 24a, 24a outside the orifice passage is suppressed compared to when a split sleeve 24 with an integral structure is used, and the magnetic flux can be more efficiently concentrated on the magnetic functional fluid in the orifice passage.

[0111] Furthermore, by adopting a pair of split sleeves 24b, 24b as illustrated in Figures 13(a) to (c), it is possible to set the axial separation distance between the pair of split sleeves 24b, 24b at the portion corresponding to the orifice passage even greater.

[0112] In the orifice member 24 of this embodiment, it is also possible to understand that the magnetic field action opening 32 is formed in the bottom wall portion 30 of the groove-shaped portion 28 in the orifice member 24 of the first embodiment with a predetermined dimension in the groove width direction (mount axial direction) of the groove-shaped portion 28 and with a length spanning the entire length in the circumferential direction (groove length direction) of the groove-shaped portion 28.

[0113] By employing such split sleeves 24b, 24b, it is possible to set the separation distance between the split sleeves 24b, 24b greater than that of the split sleeves 24a, 24a shown in Fig. 12, and more effectively prevent the magnetic flux from escaping (wandering around) through the split sleeves 24a, 24a outside the orifice passage. Also, compared to the split sleeve 24a shown in Fig. 12, the components can be made smaller, saving material, and manufacturing is easier because there is no need to form magnetic field action openings 32a in each split sleeve 24a.

[0114] Furthermore, as shown in Figures 14(a) to 14(c), the intermediate sleeve 24 may be configured as a pair of split sleeves 24c, 24c each having a semi-cylindrical shape, as if the intermediate sleeve 24 were divided along a parting line extending in the axial direction at radially opposing portions. The intermediate sleeve 24 of this embodiment is configured as a pair of split sleeves 24c, 24c, each divided along a parting line extending in the axial direction at both radially opposite portions perpendicular to the opposing direction of the groove-shaped portions 28, 28. Furthermore, although the intermediate sleeve of the embodiment shown in Figures 14(a) to 14(c) is divided into two in the circumferential direction, the intermediate sleeve may also be divided into three or more in the circumferential direction.

[0115] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific description. For example, a plurality of orifice passages may be provided, and in this case, it is sufficient that a magnetic field is applied from the magnetic field generating unit to the magnetic functional fluid in at least one of the orifice passages.

[0116] Although the orifice passage 40 in the above embodiment extends entirely in the circumferential direction, the orifice passage may extend, for example, partially in the axial or radial direction. In this case, it is desirable that the magnetic field of the magnetic field generating unit be applied to the magnetic functional fluid in the circumferentially extending portion of the orifice passage.

[0117] In the above embodiment, the coil 58 is disposed around the entire circumference of the outer cylindrical member 16 in an extrapolated state, but the coil 58 does not necessarily have to be disposed coaxially with the outer cylindrical member 16. Specifically, for example, the coil may be disposed partially around the outer periphery of the outer cylindrical member in the circumferential direction so that the central axis of the coil is located further outward than the outer cylindrical member. In this way, when current is applied to the coil, the position where the magnetic field acts on the magnetic functional fluid can be limited in the circumferential direction of the outer cylindrical member.

[0118] In the above embodiment, both of the two fluid chambers 38 are pressure-receiving chambers that generate internal pressure fluctuations when vibration is input, but for example, one of the fluid chambers may be an equilibrium chamber whose wall is partially formed of a flexible membrane. Also, the number of fluid chambers is not limited to two, and a structure having three or more fluid chambers may be adopted. [Explanation of symbols]

[0119] 10 Engine mount (vibration isolation device) (first embodiment) 12 Mount body 14 Inner shaft member 16 outer cylindrical member 18 Main body rubber elastic body 20 Stopper member 22 Protrusion 24 Intermediate sleeve (intermediate cylindrical member) 26 Window section 28 Groove 29 Axial direction both sides 30 Bottom wall part 32 Magnetic field action opening 34 Pocket-shaped part 36 Sealing rubber layer 38 Fluid chamber 39 Magnetic Functional Fluid 40 Orifice passage 41 Orifice groove 42 Magnetic flux concentrating member 44 Positioning protrusion 46 Cylindrical cover member 52,54 Support elastic body 56 Magnetic Field Generation Unit 58 Coil 60 Yoke member 62 Bobbin 64 connectors 66 Terminal section 68 Power Unit 70 Vehicle body 72 Mounting hole 80 Engine mount (vibration isolation device) (second embodiment) 81 Orifice passage 82 Orifice member 84 Partition rubber 86 Wide protrusion 88 continuous holes 90 Through hole 92 Bottom member 94 Magnetic flux concentration section 100 Engine mount (vibration isolation device) (third embodiment) 102 Orifice member 104 Opposite Surface 110 Engine mount (vibration isolation device) (fourth embodiment) 112 Orifice passage 114 Magnetic flux concentrating member 116 Magnetic pole face

Claims

1. A fluid-filled vibration-damping device in which an inner shaft member and an intermediate cylindrical member are connected by a main rubber elastic body, an outer cylindrical member is fitted and fixed onto the intermediate cylindrical member, a pocket-like portion provided in the main rubber elastic body and opening to the outer periphery of the intermediate cylindrical member is covered with the outer cylindrical member to form a plurality of fluid chambers spaced apart in the circumferential direction, and orifice passages are provided to communicate the plurality of fluid chambers, A magnetic functional fluid is sealed in the fluid chamber, a magnetic field generating unit that applies a magnetic field to the magnetic functional fluid flowing through the orifice passage is provided outside the fluid chamber; the outer cylindrical member is made of a non-magnetic material, the intermediate cylindrical member is made of a ferromagnetic material, The intermediate cylindrical member has a magnetic field action opening at a position corresponding to the orifice passage through which a magnetic field is applied to the magnetic functional fluid.

2. The intermediate cylindrical member is a pair of axially opposite portions each having a large-diameter cylindrical shape that is continuous in the circumferential direction; a groove-shaped axial intermediate portion that is partially provided in the circumferential direction and extends circumferentially between the pair of axial side portions, 2. The vibration isolation device according to claim 1, wherein the magnetic field action opening is provided in the axially intermediate portion.

3. the intermediate cylindrical member is a single member in which the pair of axially opposite portions are connected at the axially intermediate portion, 3. The vibration-damping device according to claim 2, wherein the magnetic field action opening is constituted by a window portion formed through the bottom of the groove in the axially intermediate portion of the groove.

4. the intermediate cylindrical member has a structure in which it is divided into axially opposite sides at the axially intermediate portion, and the pair of axially opposite sides are separate members, 3. The vibration isolation device according to claim 2, wherein the magnetic field action opening is formed between divided portions spaced apart in the axial direction of the axially intermediate portion.

5. 3. The vibration-damping device according to claim 1, wherein the magnetic field generating unit is disposed on the outer periphery of the outer cylindrical member.

6. 3. The vibration-damping device according to claim 1, wherein magnetic flux concentrating members made of ferromagnetic material are arranged in the orifice passage so as to face each other in the width direction of the orifice passage, and the magnetic field action opening in the intermediate cylindrical member is provided at a position corresponding to the space between the facing portions of the magnetic flux concentrating members.

7. an orifice member for forming the orifice passage is disposed between the intermediate cylindrical member and the outer cylindrical member, and extends circumferentially through an opening of the pocket-shaped portion provided in the main rubber elastic body; the orifice member is a ferromagnetic material; 7. An anti-vibration device according to claim 6, wherein the magnetic flux concentrating members arranged opposite to each other in the width direction of the orifice passage are constituted by the orifice members.

8. The magnetic field generating unit comprises: a coil member that generates a magnetic field when energized; a yoke member that guides magnetic flux in the magnetic field generated by the coil member to the orifice passage; 3. The vibration isolation device according to claim 1, further comprising:

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