Active anti-vibration device and method for manufacturing same

Abstract

The invention provides an active anti-vibration device capable of suppressing performance degradation caused by precipitation of magnetic powder based on a magneto-viscoelastic fluid in a liquid chamber without increasing the volume of the liquid chamber filled with the magneto-viscoelastic fluid. In the active anti-vibration device (1), an electromagnetic coil (12) as a magnetic field generating unit, an outer member (61) as a magnetic body, an inner member (62) as a magnetic body, a first liquid chamber (15), and a second liquid chamber (21) are provided between an inner cylinder (3) and an outer cylinder (2) in the radial direction. The first liquid chamber (15) and the second liquid chamber (21) are separated by a flexible member (14) extending in the axial direction of the inner cylinder (3), and the flexible member (14) is supported by an outer member (61) that is a magnetic body.

Description

Technical Field

[0001] The present invention relates to an active vibration isolation device and a manufacturing method thereof. Background Art

[0002] In recent years, there has been a push to integrate vulnerable groups such as the elderly, the disabled, and children into sustainable transportation systems. To achieve this goal, the inventors of this application have dedicated themselves to research and development related to vehicle rideability to further improve traffic safety and convenience.

[0003] In the past, with the purpose of improving the ride quality of a vehicle by suppressing sound and vibration in the vehicle cabin, an active vibration isolation device for use on a subframe mounting seat, a suspension bushing, etc. has been proposed (for example, see Patent Document 1). Specifically, the active vibration isolation device connects two liquid chambers filled with a magnetic viscoelastic fluid to each other through a flow path, and has an excitation coil that forms a magnetic circuit in a direction intersecting with the flow path. According to the active vibration isolation device, the magnetic viscoelastic fluid flows from one liquid chamber to the other liquid chamber in the flow path in accordance with the magnitude of the input vibration amplitude. At this time, the active vibration isolation device controls the flow of the magnetic viscoelastic fluid by making the magnetic flux density generated by the excitation coil variable. Thus, the active vibration isolation device exhibits an attenuation characteristic that corresponds freely to the magnitude of the input vibration amplitude.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-71117 Summary of the Invention

[0007] In previous active vibration isolation devices (e.g., see Patent Document 1), the volume of the liquid chamber can be increased to improve responsiveness to input vibration amplitudes. However, this increases the amount of heavy and expensive magnetic viscoelastic fluid containing magnetic powder that is required to fill the liquid chamber. This leads to new problems with active vibration isolation devices, such as increased manufacturing costs and increased vehicle weight. Furthermore, increasing the amount of magnetic viscoelastic fluid used raises the risk of the absolute amount of magnetic powder precipitated within the magnetic viscoelastic fluid increasing the active vibration isolation device's performance.

[0008] The present invention aims to provide an active vibration isolation device and a method for manufacturing the same, which can improve responsiveness to input external forces such as vibration and loads without increasing the volume of the liquid chamber filled with a magnetic viscoelastic fluid, while also suppressing performance degradation caused by sedimentation of magnetic powder in the magnetic viscoelastic fluid within the liquid chamber. Furthermore, the present invention contributes to the development of sustainable transport systems.

[0009] The active vibration isolation device of the present invention comprises: an outer cylinder; an inner cylinder arranged on the inner circumferential side of the outer cylinder; a magnetic field generating part that generates a magnetic field; a magnetic body that forms a magnetic circuit based on the magnetic field; a first liquid chamber filled with a magnetic viscoelastic fluid; and a second liquid chamber adjacent to the first liquid chamber and filled with liquid. The active vibration isolation device is characterized in that the magnetic field generating part, the magnetic body, the first liquid chamber and the second liquid chamber are arranged between the inner cylinder and the outer cylinder in the radial direction, the first liquid chamber and the second liquid chamber are separated by a flexible component, the flexible component extends in the axial direction of the inner cylinder, and a part of the first liquid chamber forms a flow path of the magnetic viscoelastic fluid located on the magnetic circuit.

[0010] In addition, the manufacturing method of the present invention is a manufacturing method of the above-mentioned active vibration isolation device, characterized in that it has the following steps: a manufacturing step of a second liquid chamber forming part, in which the elastomer is integrally molded on the outer surface of the inner cylinder to form the second liquid chamber; a manufacturing step of a first liquid chamber forming part, in which the magnetic field generating part, the magnetic body and the flexible component are combined in a liquid material composed of the magnetic viscoelastic fluid to form the first liquid chamber filled with the magnetic viscoelastic fluid; a manufacturing step of an assembly, in which the first liquid chamber and the second liquid chamber are separated by the flexible component extending along the axial direction of the inner cylinder and supported by the magnetic body, and the magnetic body and the inner cylinder are connected by the elastomer, and the first liquid chamber forming part and the second liquid chamber forming part are assembled; and a fixing step, in which the second liquid chamber is filled with the liquid by inserting the assembly into the inner side of the outer cylinder in the liquid material composed of the liquid, and the assembly is fixed in the outer cylinder.

[0011] Effects of the Invention

[0012] According to the active vibration isolation device and its manufacturing method of the present invention, the volume of the liquid chamber filled with the magnetic viscoelastic fluid will not be increased, and the response performance relative to the input external forces such as vibration and load can be improved, and the performance degradation caused by the precipitation of magnetic powder based on the magnetic viscoelastic fluid in the liquid chamber can also be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A It is a partially enlarged perspective view of a rear suspension equipped with an active anti-vibration device according to an embodiment of the present invention.

[0014] Figure 1B It is an overall perspective view of an active vibration isolation device according to an embodiment of the present invention.

[0015] Figure 2A yes Figure 1B IIA-IIA cross-sectional view.

[0016] Figure 2B yes Figure 1B IIB-IIB cross-sectional view.

[0017] Figure 3 yes Figure 1B An exploded perspective view of the active vibration isolation device shown.

[0018] Figure 4 This is an overall perspective view of an assembly of a first liquid chamber forming portion and a second liquid chamber forming portion constituting the active vibration isolation device.

[0019] Figure 5 yes Figure 1B V-V cross-sectional view.

[0020] Figure 6 This is an overall perspective view of the cage box buried in the second liquid chamber forming portion.

[0021] Figure 7 This is an exploded perspective view of the first liquid chamber forming portion constituting the active vibration isolation device.

[0022] Figure 8 is included Figure 2B A partially enlarged perspective view of the active vibration isolation device in section VIII-VIII.

[0023] Figure 9 This is a schematic diagram showing the behavior of magnetic powder when a magnetic field is applied to the hole portion of the first liquid chamber.

[0024] Figure 10A It is an overall perspective view of an active vibration isolation device according to another embodiment of the present invention.

[0025] Figure 10B yes Figure 10A XB-XB cross-sectional view.

[0026] Description of Reference Numerals

[0027] 1Active anti-vibration device

[0028] 2 outer cylinder

[0029] 3 inner tube

[0030] 6. First liquid chamber forming portion

[0031] 7 Second liquid chamber forming portion

[0032] 9 cages

[0033] 12 electromagnetic coil (magnetic field generating unit)

[0034] 14 Flexible components

[0035] 151st liquid chamber

[0036] 15a Hole

[0037] 20a liquid

[0038] 20b Magnetoviscoelastic fluid

[0039] 21 Second liquid chamber

[0040] 61 outer member (magnetic body)

[0041] 62a1 core material (magnetic material)

[0042] 62b flange (magnetic body)

[0043] Mc magnetic circuit DETAILED DESCRIPTION

[0044] Next, a mode (embodiment) for implementing the active vibration isolating device of the present invention will be described in detail with appropriate reference to the drawings.

[0045] The following description uses an active vibration isolation device applied to a vehicle suspension as an example, but the present invention is not limited thereto and can also be applied to a vehicle sound and vibration isolation device such as a mounting bushing arranged between components connected to a vehicle body frame (including a subframe).

[0046] First, after describing the overall structure of a rear suspension to which the active vibration isolator of the present embodiment is applied, the active vibration isolator will be described in further detail.

[0047] Rear Suspension

[0048] Figure 1A This is a partially enlarged perspective view of the rear suspension 30 having the active anti-vibration device 1 of this embodiment. In addition, the up, down, left, right, front, and back directions in the following description are consistent with the up, down, left, right, front, and back directions of the vehicle. Figure 1A The direction indicated by the arrow is the reference.

[0049] like Figure 1A As shown, the rear suspension 30 is a semi-trailing arm suspension, which mainly includes a suspension arm 31, a rear shock absorber 32 with one end mounted on the suspension arm 31 and the other end supported on the vehicle body frame (not shown), and a coil spring 33 supported on the suspension arm 31.

[0050] The suspension arm 31 includes a trailing arm 34 , a cross member 35 , and a knuckle 36 that supports a rear wheel (not shown) provided on the trailing arm 34 .

[0051] A bushing 37 is attached to the front end of the trailing arm 34 for swingably attaching the trailing arm 34 to a vehicle body frame (not shown).

[0052] The bushing 37 is an active vibration isolation device of the present embodiment, and is hereinafter referred to as an active vibration isolation device 1 .

[0053] The front end of the trailing arm 34 is attached to the outer cylinder 2 (see FIG. Figure 2A ). In addition, the active anti-vibration device 1 is mounted on a predetermined bracket (not shown) provided on a vehicle body frame (not shown) via a support shaft 38. Incidentally, the support shaft 38 is inserted into the inner tube 3 (see Figure 2A ).

[0054] "Active anti-vibration device"

[0055] Figure 1B It is an overall perspective view of the active vibration isolation device 1 according to the present embodiment. Figure 2A yes Figure 1B IIA-IIA cross-sectional view. Figure 2B yes Figure 1B IIB-IIB cross-sectional view. In addition, Figure 1B For the convenience of drawing, the outer cylinder 2 of the components of the active vibration isolation device 1 is depicted by a solid line, and the inner cylinder 3, the first liquid chamber forming portion 6, and the second liquid chamber forming portion 7 arranged inside the outer cylinder 2 are depicted by a dotted line. Figure 1B In the drawings, reference numeral 14 denotes a flexible member of the first liquid chamber forming portion 6 that faces the outer side of the second liquid chamber forming portion 7 with a slit 7 b 1 (described later) of the second liquid chamber forming portion 7 interposed therebetween.

[0056] like Figure 1B As shown, the active vibration isolating device 1 has a cylindrical outer shape.

[0057] like Figure 2A as well as Figure 2B As shown, the active vibration isolator 1 includes an outer cylinder 2 and an inner cylinder 3 disposed substantially coaxially on the inner circumference of the outer cylinder 2 .

[0058] In addition, between the outer tube 2 and the inner tube 3, a first liquid chamber 15 (see Figure 5 ) of the first liquid chamber forming portion 6 (see Figure 5 ), and forming the second liquid chamber 21 (refer to Figure 5 ) of the second liquid chamber forming portion 7 (see Figure 5 ).

[0059] And, as Figure 2B As shown in FIG. 1 , a hole portion 15a is formed in the first liquid chamber forming portion 6 as a part of the first liquid chamber 15. The hole portion 15a is formed to be larger than Figure 2A The cross-sectional area of ​​the first liquid chamber 15 shown as the common portion is narrow, and the throttling portion is formed. Figure 2BWhen a magnetic circuit Mc is formed by the magnetic field generated by the electromagnetic coil 12 (magnetic field generating unit), the hole portion 15a is located on the magnetic circuit Mc.

[0060] <Outer cylinder>

[0061] like Figure 2A as well as Figure 2B As shown, the outer cylinder 2 is formed of a cylindrical body with a bottom.

[0062] The outer tube 2 includes a cylindrical outer tube body 24 and a lid 25 that closes one open end of the outer tube body 24 .

[0063] The cover 25 includes a disk portion 25a disposed so as to abut against one end surface of the inner tube 3, and a cylindrical elastic portion 25b made of synthetic rubber that vulcanization-bonds the end of the outer tube body 24 to the cover 25. The disk portion 25a also has an opening 25a1 at its center that has the same diameter as the hole 3a of the inner tube 3.

[0064] In this embodiment, the outer cylinder body 24 and the disk portion 25 a of the lid 25 are assumed to be made of a non-magnetic material.

[0065] Examples of the non-magnetic material include aluminum alloy, non-ferrite SUS, copper, etc., but the non-magnetic material is not limited thereto.

[0066] <Inner tube>

[0067] like Figure 2A as well as Figure 2B As shown, the inner tube 3 is formed longer in the axial direction than the outer tube body 24. Furthermore, the axial end of the inner tube 3 slightly protrudes axially outward from the end of the outer tube body 24. Furthermore, the inner tube 3 of this embodiment is assumed to be formed of a non-magnetic material.

[0068] The support shaft 38 (see FIG. 2 ) is inserted into the hole 3a of the inner tube 3 and the opening 25a1 of the disk portion 25a. Figure 1A The active vibration isolator 1 is connected to the support shaft 38 (see Figure 1A ) is supported on the vehicle body frame (not shown).

[0069] <First Liquid Chamber Forming Portion and Second Liquid Chamber Forming Portion>

[0070] Next, the first liquid chamber forming portion 6 ( Figure 2A ) and the second liquid chamber forming portion 7 ( Figure 2A Here, in describing the second liquid chamber forming portion 7 ( Figure 2A ) Next, the first liquid chamber forming portion 6 ( Figure 2A ).

[0071] Figure 3 It is an active vibration isolation device 1 (refer to Figure 2A ) is an exploded perspective view of the .

[0072] like Figure 3 As shown, the second liquid chamber forming portion 7 has a substantially gyro shape with the inner tube 3 as an axis.

[0073] Specifically, the second liquid chamber-forming portion 7 comprises a generally cylindrical portion 7a that is press-fitted into the interior of the outer tube body 24, and a cylindrical portion 7b that is fitted into the small-diameter cylindrical portion 61a of the first liquid chamber-forming portion 6, described later. The generally cylindrical portion 7a and the cylindrical portion 7b have the same outer diameter and are coaxially formed integrally with each other. Furthermore, the cylindrical portion 7b is press-fitted into the interior of the outer tube body 24 together with the generally cylindrical portion 7a.

[0074] Figure 3 In the figure, reference numeral R denotes ribs formed on the outer peripheral surface of the second liquid chamber forming portion 7. These ribs R serve as a rib filled with the liquid 20a described later when the second liquid chamber forming portion 7 is pressed into the inner side of the outer tube body 24 (see Figure 5 ) of the second liquid chamber 21 (refer to Figure 5 ) to function as a sealing component.

[0075] like Figure 3 As shown, a pair of grooves 7a1 are formed in the substantially cylindrical portion 7a. The pair of grooves 7a1 extend along the circumference of the substantially cylindrical portion 7a at positions sandwiching the inner cylinder 3. The pair of grooves 7a1 are formed so as to face each other at 180 degrees with the inner cylinder 3 interposed therebetween.

[0076] That is, a pair of groove portions 7a1 are formed in the substantially cylindrical portion 7a so as to sandwich the partition wall 7a2 extending in the radial direction of the substantially cylindrical portion 7a.

[0077] A pair of slits 7b1 is formed in the cylindrical portion 7b. Each of the pair of slits 7b1 extends in the circumferential direction of the cylindrical portion 7b so as to be aligned in the axial direction with respect to each of the pair of grooves 7a1.

[0078] Furthermore, as described below, the opening of the slit 7b1 facing the inner surface of the cylindrical portion 7b is closed liquid-tightly by the flexible member 14 when the small-diameter cylindrical portion 61a of the first liquid chamber forming portion 6 is fitted inside the cylindrical portion 7b.

[0079] Figure 4 It is an overall perspective view of the assembly As of the second liquid chamber forming portion 7 and the first liquid chamber forming portion 6 .

[0080] like Figure 4 As shown, the assembly As is a small diameter cylindrical portion 61a of the first liquid chamber forming portion 6 (see Figure 3 ) is pressed into the inner side of the cylindrical portion 7b of the second liquid chamber forming portion 7.

[0081] As a result, the opening of the slit 7b1 facing the inner peripheral side of the cylindrical portion 7b is closed liquid-tightly by the flexible member 14 described in detail later.

[0082] The slit 7b1 thus forms a groove 7c extending in the circumferential direction of the cylindrical portion 7b with the flexible member 14 as the bottom. In other words, the groove 7c is formed to correspond to the groove 7a1 of the substantially cylindrical portion 7a.

[0083] Furthermore, the second liquid chamber forming portion 7 includes a groove portion 7d connecting the groove portion 7a1 and the groove portion 7c.

[0084] In this embodiment, a pair of grooves 7d are formed, extending from both circumferential ends of groove 7c toward groove 7a1. Specifically, grooves 7d are formed within the second liquid chamber-forming portion 7, extending from the substantially cylindrical portion 7a to the cylindrical portion 7b. These grooves 7d are formed by partially recessing the outer circumferences of the substantially cylindrical portion 7a and the cylindrical portion 7b radially inward.

[0085] Figure 5 yes Figure 1B The V-V cross-sectional view of the Figure 5 The figure shows an assembly As in which the second liquid chamber forming portion 7 and the first liquid chamber forming portion 6 are arranged inside the outer tube 2 .

[0086] like Figure 5 As shown, the groove portion 7a1 of the second liquid chamber forming portion 7 is closed by the inner peripheral surface of the outer tube 2 to form the main liquid chamber 21a.

[0087] Furthermore, the groove portion 7 c of the second liquid chamber forming portion 7 is closed by the inner peripheral surface of the outer tube 2 to form an adjacent liquid chamber 21 b adjacent to the main liquid chamber 21 a .

[0088] Furthermore, the groove portion 7d of the second liquid chamber forming portion 7 is closed by the inner peripheral surface of the outer tube 2 to form a connecting passage 21c connecting the main liquid chamber 21a and the adjacent liquid chamber 21b.

[0089] The main liquid chamber 21 a , the adjacent liquid chamber 21 b , and the connecting passage 21 c are integrated to form the second liquid chamber 21 .

[0090] Specifically, the second liquid chamber 21 includes an adjacent liquid chamber 21b located radially outward from the flexible member 14, and a main liquid chamber 21a located axially opposite the adjacent liquid chamber 21b across the elastic body 8. Furthermore, the active vibration isolation device 1 includes a connecting passage 21c connecting the main liquid chamber 21a and the adjacent liquid chamber 21b between the cage case 9 and the outer tube 2.

[0091] The second liquid chamber 21 is filled with a liquid 20a that is a medium for transmitting vibrations, etc. As the liquid 20a, for example, a well-known hydraulic oil such as silicone oil or grease oil can be appropriately used.

[0092] like Figure 5 As shown, the structure of this second liquid chamber forming part 7 includes: an elastomer 8, which forms a roughly cylindrical part 7a and a cylindrical part 7b arranged between the outer tube main body 24 of the outer tube 2 and the inner tube 3; and a roughly cylindrical cage box 9, which is buried in the elastomer 8 in a manner along the inner circumferential surface of the outer tube 2.

[0093] The elastic body 8 of this embodiment is assumed to be a molded product of synthetic rubber and is bonded to the outer peripheral surface of the inner tube 3 by vulcanization.

[0094] And, as Figure 5 As shown, the elastic body 8 includes a tubular covering portion 8a that supports the substantially cylindrical portion 7a and the cylindrical portion 7b on the inner tube 3. The tubular covering portion 8a covers substantially the entire outer peripheral surface of the inner tube 3.

[0095] This elastic body 8 elastically supports the second liquid chamber forming portion 7 and the first liquid chamber forming portion 6, which is integrated with the second liquid chamber forming portion 7 via the outer tube 2, on the outer peripheral surface of the inner tube 3. In other words, the elastic body 8 cooperates with the cylindrical elastic portion 25b constituting the outer tube 2 to allow relative displacement of the inner tube 3 with respect to the outer tube main body 24 in a direction perpendicular to the axis.

[0096] The cage case 9 is embedded in the elastic body 8 by insert molding. Figure 6 It is an overall three-dimensional view of the cage box 9.

[0097] like Figure 6 As shown, the cage box 9 has a main liquid chamber 21a (refer to Figure 5 ) corresponding to the two cutout portions 9a; with the adjacent liquid chamber 21b (reference Figure 5 ) two cutout portions 9b formed in a corresponding manner.

[0098] The cage 9 is a generally cylindrical body formed of a thin metal plate. Figure 2B As shown, the cage 9 encloses the elastic body 8 radially inward.

[0099] As will be described in detail later, the cage box 9 is formed by reducing the diameter of the cage box 9 so as to be used as a support for the elastic body 8 (see Figure 2B ) is formed by vulcanizing to release the residual strain generated by the strain relief component and function.

[0100] As the material of the cage box 9, for example, steel plate, aluminum plate, copper plate, titanium plate, etc. can be cited, but it is not limited to these as long as it can be processed into a diameter reduction. Among them, as the material of the cage box 9, steel plate is preferable.

[0101] Next, the first liquid chamber forming portion 6 (see Figure 3 ).

[0102] like Figure 3 As shown, the first liquid chamber forming portion 6 includes the flexible member 14 , an outer member 61 to which the flexible member 14 is attached, and an inner member 62 housed inside the outer member 61 .

[0103] Figure 7 It is an exploded perspective view of the first liquid chamber forming portion 6 .

[0104] like Figure 7 As shown, the outer member 61 includes a small-diameter cylindrical portion 61 a and a large-diameter cylindrical portion 61 b ​​having a larger diameter than the small-diameter cylindrical portion 61 a .

[0105] A pair of slit-shaped cutouts 61a1 extending in the circumferential direction are formed in the small-diameter cylindrical portion 61a. The circumferential length of the cutouts 61a1 corresponds to the second liquid chamber forming portion 7 (see Figure 4 ) in the groove 7c (see Figure 4 ) circumferential length.

[0106] Furthermore, the cutout portion 61a1 allows the inside and outside of the small-diameter cylindrical portion 61a to communicate with each other.

[0107] Incidentally, the outer member 61 is formed of a magnetic body such as iron, cobalt, nickel, or an alloy of these elements.

[0108] like Figure 7 As shown, the flexible member 14 is attached to the small-diameter cylindrical portion 61 a so as to close the cutout portion 61 a 1 from the outside of the small-diameter cylindrical portion 61 a .

[0109] The flexible member 14 is formed of an elongated plate body made of synthetic rubber that is curved along the outer peripheral surface of the small-diameter cylindrical portion 61 a .

[0110] Locked rings 14a are formed at both ends in the longitudinal direction of the flexible member 14. The locked rings 14a fit into locking protrusions 61a2 formed on the outer peripheral surface of the small-diameter cylindrical portion 61a, thereby attaching the flexible member 14 to the outer peripheral surface of the small-diameter cylindrical portion 61a.

[0111] By the way, if Figure 2A As shown, the flexible member 14 is arranged so that the plate width direction of the flexible member 14 extends along the axial direction of the inner tube 3 .

[0112] Furthermore, the flexible member 14 of this embodiment is sandwiched between the inner peripheral surface of the cylindrical portion 7 b in the second liquid chamber forming portion 7 and the outer peripheral surface of the small-diameter cylindrical portion 61 a in the first liquid chamber forming portion 6 .

[0113] However, the support structure of the flexible member 14 is not limited to this, and the flexible member 14 may be configured to be integrally connected to at least one of the cylindrical portion 7 b and the small-diameter cylindrical portion 61 a .

[0114] like Figure 7 As shown, the inner member 62 includes an insert cylindrical portion 62a inserted into the inner side of the small diameter cylindrical portion 61a of the outer member 61, and a flange portion 62b formed at one axial end of the insert cylindrical portion 62a.

[0115] And, as Figure 2B As shown, the outer diameter of the flange portion 62 b is set so as to be accommodated on the inner peripheral side of the large-diameter cylindrical portion 61 b ​​in the outer member 61 .

[0116] like Figure 2B As shown, the fitting cylindrical portion 62a of the inner member 62 is configured such that a coating 62a2 made of synthetic rubber is provided on the surface of a cylindrical core material 62a1 made of a magnetic body.

[0117] And, as Figure 2B As shown, the entire surface of the insertion cylindrical portion 62a is provided with a coating 62a2 except for a portion where a hole portion 15a, which will be described in detail later, is formed.

[0118] The flange portion 62b of the inner member 62 is formed of a magnetic material and is formed to continuously extend from one axial end portion of the core material 62a1 toward the outer circumference. Examples of the magnetic material forming the core material 62a1 and the flange portion 62b include iron, cobalt, nickel, and alloys of these elements.

[0119] like Figure 5 As shown, when the inner member 62 is pressed into the inner side of the outer member 61, the coating 62a2 of the embedded cylindrical portion 62a in the inner member 62 comes into close liquid-tight contact with the inner circumferential surface of the small-diameter cylindrical portion 61a in the outer member 61. The slit-like notch 61a1 formed in the small-diameter cylindrical portion 61a forms the first liquid chamber 15 between the flexible member 14 and the embedded cylindrical portion 62a.

[0120] The first liquid chamber 15 is filled with a magneto-rheological fluid 20b. As the magneto-rheological fluid 20b, a known MRF (Magneto-Rheological Fluid) or MRC (Magneto-Rheological Compound) obtained by dispersing magnetic powder in mineral oil or synthetic oil can be used as appropriate.

[0121] Next, the structure of the first liquid chamber 15 (see Figure 5 ) of a portion of the hole portion 15a (see Figure 2B ).

[0122] Figure 8 is included Figure 2B A partially enlarged perspective view of the active vibration isolation device 1 at section VIII-VIII.

[0123] like Figure 8 As shown, the first liquid chamber 15 extends in an annular shape along the circumferential direction of the first liquid chamber forming portion 6 , except for a separation portion 15 c provided at a position opposing the hole portion 15 a across the inner tube 3 .

[0124] The hole portion 15 a as a part of the first liquid chamber 15 is formed to have a cross-sectional area smaller than a cross-sectional area in the radial direction of the common portion 15 b of the first liquid chamber 15 .

[0125] As described above, the common portion 15 b of the first liquid chamber 15 is formed between the inner side surface of the flexible member 14 and the outer peripheral surface of the fitting cylindrical portion 62 a .

[0126] In contrast, the hole portion 15a does not have Figure 7 The gap between the rectangular area Ar of the coating film 62a2 shown in FIG. 1 and the small diameter cylindrical portion 61a of the outer member 61 opposite to the rectangular area Ar is formed. Figure 8 As shown, the hole portion 15a is formed by a gap corresponding to the thickness of the coating film 62a2 embedded in the cylindrical portion 62a.

[0127] Furthermore, when the active vibration isolation device 1 of this embodiment is installed Figure 1A When the rear suspension 30 is shown, Figure 8 As shown, the hole portion 15a is located vertically downward.

[0128] also, Figure 5 The connection passage 21c in the second liquid chamber forming portion 7 shown is set so that the resistance of the liquid 20a when flowing in the connection passage 21c is smaller than the resistance of the magnetic viscoelastic fluid 20b when the magnetic field from the electromagnetic coil 12 (magnetic field generating portion) is not applied. Figure 8 The cross-sectional area of ​​the hole portion 15a shown represents the resistance to flow.

[0129] In addition, if Figure 7 As shown, the first liquid chamber forming portion 6 is configured such that the electromagnetic coil 12 (magnetic field generating portion) is housed inside the large-diameter cylindrical portion 61 b ​​of the outer member 61 .

[0130] Specifically, if Figure 2B As shown, the electromagnetic coil 12 is arranged in an annular space portion surrounded by a large-diameter cylindrical portion 61 b ​​of an outer member 61 and a flange portion 62 b of an inner member 62 to be described below.

[0131] And, as Figure 2B As shown, when the inner member 62 is press-fitted into the inner side of the outer member 61 , the large-diameter cylindrical portion 61 b ​​of the outer member 61 and the inner member 62 are magnetically coupled.

[0132] Furthermore, the coating film 62a2 magnetically insulates the small-diameter cylindrical portion 61a of the outer member 61 from the core material 62a1 fitted into the cylindrical portion 62a, except for the portion where the hole portion 15a is formed.

[0133] Thus, the outer member 61 , the core 62 a 1 of the inner member 62 , and the flange portion 62 b of the inner member 62 form a magnetic path Mc passing through the magneto-viscoelastic fluid 20 b in the hole 15 a due to the magnetic field generated by the electromagnetic coil 12 .

[0134] The outer member 61 , the core material 62 a 1 of the inner member 62 , and the flange portion 62 b of the inner member 62 constitute what is referred to as a “magnetic body” in the claims.

[0135] like Figure 5 As shown, the first liquid chamber forming portion 6 is not directly connected to the elastic body 8. Specifically, the first liquid chamber forming portion 6 is embedded in the second liquid chamber forming portion 7 and embedded in the outer tube 2. In other words, the first liquid chamber forming portion 6 is separated from the inner tube 3 and arranged radially outward.

[0136] 《Operation of active vibration isolation device》

[0137] First, the operation of the active vibration isolation device 1 in a state where no power is supplied to the electromagnetic coil 12 will be described.

[0138] like Figure 5 As shown, in the active vibration isolation device 1 , if an external force L such as a load or vibration amplitude is input to the inner cylinder 3 in a direction perpendicular to the axis, the relative positions of the inner cylinder 3 and the outer cylinder 2 are displaced.

[0139] exist Figure 5 In the case shown, the inner cylinder 3 is displaced toward the outer cylinder 2, thereby Figure 5 The hydraulic pressure of the liquid 20a in the second liquid chamber 21 on the P side increases. In addition, in the second liquid chamber 21 on the Q side opposite to the inner tube 3, the inner tube 3 is displaced away from the outer tube 2, thereby reducing the hydraulic pressure of the liquid 20a.

[0140] When the hydraulic pressure of the liquid 20a in the second liquid chamber 21 on the P side increases, the flexible member 14 on the P side is pressed toward the first liquid chamber 15, that is, toward the inner tube 3. On the other hand, when the hydraulic pressure of the liquid 20a in the second liquid chamber 21 on the Q side decreases, the flexible member 14 is pulled away from the inner tube 3.

[0141] That is, in the active vibration isolation device 1, Figure 8 As shown, the magnetic viscoelastic fluid 20b in the common portion 15b of the first liquid chamber 15 on the P side moves toward the common portion 15b of the first liquid chamber 15 on the Q side. The magnetic viscoelastic fluid 20b generates a flow F passing through the hole portion 15a.

[0142] And, in Figure 5 On the P side shown, when the flexible member 14 is pressed toward the inner tube 3, the liquid 20a flows from the main liquid chamber 21a to the adjacent liquid chamber 21b via the connecting passage 21c.

[0143] When the liquid 20a flows in the connecting passage 21c, flow resistance is generated.

[0144] The active vibration isolation device 1 exhibits a damping characteristic of input vibration and the like by the flow resistance of the liquid 20 a .

[0145] In addition, if Figure 8 As shown, when the magnetic viscoelastic fluid 20b flows from the common portion 15b in the first liquid chamber 15 on the P side to the common portion 15b in the first liquid chamber 15 on the Q side via the hole portion 15a, flow resistance is generated.

[0146] The active vibration isolation device 1 exhibits a damping characteristic of input vibration and the like by the flow resistance of the magneto-viscoelastic fluid 20 b .

[0147] Next, the operation of the active vibration isolation device 1 in a state where the electromagnetic coil 12 is energized will be described.

[0148] like Figure 2B As shown, the magnetic field generated by the electromagnetic coil 12 after energization forms a magnetic path Mc passing through the magneto-viscoelastic fluid 20 b in the hole portion 15 a.

[0149] Figure 9 Schematic diagram showing the behavior of the magnetic powder Mp when a magnetic field is applied to the hole portion 15 a of the first liquid chamber 15 .

[0150] Figure 9 As shown in the left figure, the magneto-viscoelastic fluid 20b in the hole portion 15a of the first liquid chamber 15 maintains the dispersed state of the magnetic powder Mp and exhibits desired fluidity when no magnetic field is applied.

[0151] In contrast, Figure 9 As shown in the figure on the right, if the magnetic field generated forms a magnetic circuit Mc (see Figure 2B ), the magnetic powder Mp is aligned along the magnetic flux ML. As a result, the apparent viscosity of the magnetic viscoelastic fluid 20b increases, and the aligned magnetic powder Mp becomes a valve body, thereby generating flow resistance in the hole portion 15a.

[0152] The active vibration isolation device 1 exhibits a characteristic of damping input vibrations and the like due to the flow resistance of the magneto-viscoelastic fluid 20 b in the hole portion 15 a .

[0153] Furthermore, by controlling the value of the current flowing in the electromagnetic coil 12 according to the magnitude of the input vibration or the like, the attenuation characteristics of the vibration or the like can be made variable.

[0154] The active vibration isolation device 1 of this embodiment is configured such that, when a load and vibration amplitude are externally input to at least one of the inner tube 3 or the outer tube 2, a flow of the magneto-viscoelastic fluid 20b within the first liquid chamber 15 is generated in response to changes in the hydraulic pressure of the liquid 20a within the second liquid chamber 21. Furthermore, the active vibration isolation device 1 controls the vibration damping characteristics by adjusting the magnitude of the magnetic field (magnetic flux density) applied to the hole portion 15a of the first liquid chamber 15.

[0155] According to this active vibration isolation device 1, unlike previous active vibration isolation devices (for example, refer to patent document 1) that directly convert input such as vibration from the outside into the flow of magneto-viscoelastic fluid, the flow of magneto-viscoelastic fluid 20b in the first liquid chamber 15 is generated by the hydraulic pressure change of the liquid 20a in the second liquid chamber 21.

[0156] Manufacturing Method

[0157] Next, while mainly referring to Figure 5 A method for manufacturing the active vibration isolator 1 will be described while referring to the reference numerals shown in FIG.

[0158] The manufacturing method includes the following steps: a manufacturing step of the second liquid chamber forming portion 7, wherein the elastic body 8 is integrally formed on the outer surface of the inner cylinder 3 to form the second liquid chamber 21; a manufacturing step of the first liquid chamber forming portion 6, wherein the electromagnetic coil 12 as the magnetic field generating portion, the outer member 61 as the magnetic body, the inner member 62 as the magnetic body, and the flexible member 14 are combined in a liquid material composed of the magnetic viscoelastic fluid to form the first liquid chamber 15 filled with the magnetic viscoelastic fluid 20b; an assembly As (see Figure 4 ) manufacturing process, which is to assemble the first liquid chamber forming part 6 and the second liquid chamber forming part 7 in such a manner that the first liquid chamber 15 and the second liquid chamber 21 are separated by the flexible member 14 extending in the axial direction of the inner tube 3 and supported by the magnetic body, and the magnetic body and the inner tube 3 are connected by the elastic body 8; and a fixing process, which is to assemble the assembly As (refer to Figure 4 ) is inserted into the inner side of the outer tube 2 in the liquid material composed of the liquid 20a and the second liquid chamber 21 is filled with the liquid 20a, and the assembly As (refer to Figure 4 ) is fixed in the outer tube 2.

[0159] In addition, the fixing step in this manufacturing method further includes a step of reducing the diameter of the outer tube body 24 of the outer tube 2 toward the radial inner side.

[0160] In this diameter-reducing process, the outer cylinder body 24 is plastically deformed so as to be slightly reduced in diameter.

[0161] Furthermore, as the outer tube body 24 is reduced in diameter, the cage case 9 disposed inside the outer tube body 24 is also slightly reduced in diameter.

[0162] The elastic body 8 disposed between the outer tube main body 24 and the inner tube 3 is compressed. The residual strain generated in the elastic body 8 that has shrunk after vulcanization is released by this diameter reduction process.

[0163] Effects

[0164] Next, the effects achieved by the active vibration isolation device 1 of the present embodiment will be described.

[0165] The active vibration isolation device 1 of this embodiment is different from the previous active vibration isolation device (for example, refer to patent document 1) that directly converts input such as vibration from the outside into the flow of magnetic viscoelastic fluid. As mentioned above, the flow of magnetic viscoelastic fluid 20b in the first liquid chamber 15 is generated by the hydraulic pressure change of the liquid 20a in the second liquid chamber 21.

[0166] According to the active vibration isolation device 1 of this embodiment, the volume of the first liquid chamber 15 filled with the magnetic viscoelastic fluid 20b will not be increased. By increasing the volume of the second liquid chamber 21 filled with the liquid 20a, it is possible to seek to improve the response performance relative to the input external forces such as vibration and load.

[0167] In addition, according to the active vibration isolation device 1, unlike previous active vibration isolation devices (for example, refer to patent document 1), the volume of the liquid chamber (first liquid chamber 15) filled with the magnetic viscoelastic fluid 20b can be made relatively smaller, thereby reducing the use of the magnetic viscoelastic fluid 20b containing the relatively heavy and expensive magnetic viscoelastic fluid Mp.

[0168] In addition, according to the active vibration isolation device 1, unlike previous active vibration isolation devices (for example, refer to patent document 1), the volume of the liquid chamber (first liquid chamber 15) filled with the magnetic viscoelastic fluid 20b can be made relatively smaller, thereby reducing the absolute amount of magnetic powder Mp precipitated in the magnetic viscoelastic fluid 20b.

[0169] In addition, according to the active vibration isolation device 1, the volume of the liquid chamber (first liquid chamber 15) filled with the magnetic viscoelastic fluid 20b can be made relatively small, so that the magnetic powder Mp can be redispersed by the rolling action of the precipitated magnetic powder Mp generated based on the flow F of the magnetic viscoelastic fluid 20b.

[0170] Furthermore, according to the active vibration isolator 1 , it is possible to suppress the sedimentation of the magnetic powder Mp due to the passage of time, and to maintain good vibration and other damping performance.

[0171] Furthermore, in the active vibration isolation device 1 , the first liquid chamber 15 , the second liquid chamber 21 , and the flexible member 14 extend in the circumferential direction.

[0172] According to such an active vibration isolation device 1 , it is possible to achieve a compact device while maintaining good response performance to input vibrations and the like.

[0173] In the active vibration isolation device 1, the electromagnetic coil 12 serving as the magnetic field generator, the outer member 61 serving as a magnetic body, the inner member 62 serving as a magnetic body, the first liquid chamber 15, and the second liquid chamber 21 are provided radially between the inner cylinder 3 and the outer cylinder 2. Furthermore, the first liquid chamber 15 and the second liquid chamber 21 are separated by a flexible member 14.

[0174] According to the active vibration isolation device 1 , the liquid 20 a in the second liquid chamber 21 can efficiently generate the flow F of the magneto-viscoelastic fluid 20 b in the first liquid chamber 15 in response to vibration or the like input from either the inner tube 3 or the outer tube 2 .

[0175] Furthermore, in the active vibration isolation device 1 , the flexible member 14 extends in the axial direction of the inner tube 3 .

[0176] According to this active vibration isolation device 1, for example, unlike the case where the flexible member 14 extends in a direction perpendicular to the axis of the inner cylinder 3 and the width of the flexible member 14 is limited to being less than the distance between the outer cylinder 2 and the inner cylinder 3, the width of the flexible member 14 can be ensured to be large in the axial direction of the inner cylinder 3.

[0177] In other words, the active vibration isolator 1 can be configured with the hole 15a widened in the axial direction without increasing the outer diameter of the active vibration isolator 1. This allows the active vibration isolator 1 to increase the liquid column resonance frequency without generating a magnetic field from the electromagnetic coil 12. This increases the low spring frequency range of the active vibration isolator 1.

[0178] Furthermore, according to the active vibration isolation device 1 , the width of the hole portion 15 a can be increased in the axial direction, and thus the film rigidity of the flexible member 14 can be reduced when the magnetic field by the electromagnetic coil 12 is not generated.

[0179] In the active vibration isolation device 1 , the flexible member 14 is held by the cage 9 located radially outward and the magnetic outer member 61 located radially inward relative to the cage 9 . The elastic body 8 is connected to the cage 9 but not to the outer member 61 .

[0180] According to this active vibration isolation device 1, the elastic body 8 is not directly connected to the outer member 61 but is connected only to the cage 9, thereby extending the elastic body 8 (rubber leg). This improves the durability of the elastic body 8 that expands and contracts due to vibrations.

[0181] In the active vibration isolation device 1 , the outer cylinder 2 is subjected to a diameter reduction process toward the radial inner side in a state where the cage case 9 is located inside.

[0182] According to such an active vibration isolation device 1 , the outer cylinder 2 and the cage case 9 can be more reliably integrated.

[0183] Furthermore, according to the active vibration isolation device 1 , the outer tube 2 and the cage 9 can be reduced in diameter radially inward, thereby reducing the residual strain of the elastic body 8 during vulcanization molding.

[0184] In the active vibration isolation device 1 , the cage 9 is formed only of the cylindrical portion extending along the outer cylinder 2 .

[0185] According to the active vibration isolation device 1 , the cage 9 is composed of only the cylindrical portion, and thus the diameter reduction process is easy.

[0186] Furthermore, in the active vibration isolator 1, the second liquid chamber 21 includes an adjacent liquid chamber 21b located radially outwardly of the flexible member 14, and a main liquid chamber 21a located axially opposite to the adjacent liquid chamber 21b across the elastic body 8. Furthermore, the active vibration isolator 1 includes a connecting passage 21c connecting the main liquid chamber 21a and the adjacent liquid chamber 21b between the cage case 9 and the outer tube 2.

[0187] Although it is envisaged that the capacity of the adjacent liquid chamber 21b decreases when the flexible member 14 is brought closer to the outer tube 2, according to the active vibration isolation device 1, the main liquid chamber 21a and the adjacent liquid chamber 21b are connected via the connecting passage 21c, thereby ensuring a greater overall capacity of the second liquid chamber 21.

[0188] In addition, in the active vibration isolation device 1, the connecting passage 21c is set so that the resistance of the liquid 20a when flowing in the connecting passage 21c is smaller than the cross-sectional area of ​​the resistance when the magnetic viscoelastic fluid 20b flows from the hole portion 15a in the state where no magnetic field from the electromagnetic coil 12 (magnetic field generating unit) acts.

[0189] If the flow resistance in the connecting passage 21c of the liquid 20a is greater than the flow resistance in the hole 15a of the magnetic viscoelastic fluid 20b, the amplitude of the change in rigidity when the magnetic field is changed by the electromagnetic coil 12 (magnetic field generator) decreases. In other words, the controllable frequency band is narrowed. In contrast, the active vibration isolation device 1 can prevent the controllable frequency band from narrowing.

[0190] In the active vibration isolation device 1 , the first liquid chamber 15 is provided between the flexible member 14 and the outer member 61 , which is a magnetic body, and the second liquid chamber 21 is provided between the flexible member 14 and the outer tube 2 .

[0191] According to the active vibration isolation device 1 , after forming the first liquid chamber 15 filled with the magnetic viscoelastic fluid 20 b , the filling process of the second liquid chamber 21 filled with the liquid 20 a with the magnetic viscoelastic fluid 20 b and the liquid 20 a can be easily performed.

[0192] The manufacturing method of the active vibration isolation device 1 includes the following steps: a manufacturing step of the second liquid chamber forming portion 7, in which the elastic body 8 is integrally molded on the outer surface of the inner cylinder 3 to form the second liquid chamber 21; a manufacturing step of the first liquid chamber forming portion 6, in which the electromagnetic coil 12 (magnetic field generating portion), the outer member 61 as a magnetic body, the inner member 62 as a magnetic body, and the flexible member 14 are combined in a liquid material composed of a magnetic viscoelastic fluid to form a first liquid chamber filled with a magnetic viscoelastic fluid 20b. 15; a manufacturing process of the assembly As, which assembles the first liquid chamber forming portion 6 and the second liquid chamber forming portion 7 in such a manner that the first liquid chamber 15 and the second liquid chamber 21 are separated by a flexible member 14 extending axially along the inner tube 3 and supported by the magnetic body, and the magnetic body and the inner tube 3 are connected by the elastic body 8; and a fixing process, which fills the second liquid chamber 21 with the liquid 20a by inserting the assembly As into the inner side of the outer tube 2 in a liquid substance composed of the liquid 20a, and fixes the assembly As in the outer tube 2.

[0193] In conventional methods for manufacturing active vibration isolation devices (e.g., see Patent Document 1), after the active vibration isolation device is assembled, a magnetic viscoelastic fluid is filled into the liquid chamber through a predetermined filling hole. This conventional manufacturing method has the potential to reduce vibration damping performance due to bubbles remaining in the liquid chamber.

[0194] In contrast, in the method for manufacturing the active vibration isolation device 1 , before assembling the entire device, the assembly As is preliminarily combined in a liquid substance composed of the magnetic viscoelastic fluid 20 b , thereby filling the first liquid chamber 15 with the magnetic viscoelastic fluid 20 b .

[0195] According to the manufacturing method of this embodiment, it is possible to prevent bubbles from remaining in the magneto-viscoelastic fluid 20 b in the first liquid chamber 15 .

[0196] In the method for manufacturing the active vibration isolator 1 , the fixing step further includes a step of reducing the diameter of the outer cylinder 2 toward the radial inner side.

[0197] According to the manufacturing method of the active vibration isolation device 1, the outer cylinder 2 and the cage case 9 can be more reliably integrated.

[0198] Furthermore, according to the method for manufacturing the active vibration isolation device 1 , it is possible to reduce the residual strain of the elastic body 8 during vulcanization molding.

[0199] The active anti-vibration device 1 of the present embodiment can be appropriately used as a substitute for various conventional mount bushes and suspension bushes that need to be carefully determined in consideration of safety performance, sportiness, comfort performance, and ride performance.

[0200] As mentioned above, although this embodiment was described, this invention is not limited to the said embodiment, It can be implemented in various forms.

[0201] like Figure 8 As shown, the active vibration isolating device 1 of the above embodiment assumes a case where the hole portion 15 a is provided only at the lower portion in the vertical direction, but the present invention is not limited thereto.

[0202] Figure 10A It is an overall perspective view of an active vibration isolating device 1A according to another embodiment of the present invention. Figure 10B yes Figure 10A XB-XB cross-sectional view.

[0203] In the active vibration isolator 1A, the same components as those of the active vibration isolator 1 of the above-described embodiment are denoted by the same reference numerals and their detailed descriptions are omitted. Figure 10A In FIG, the outer cylinder 2 is indicated by an imaginary line (two-dot chain line).

[0204] like Figure 10A As shown, the active anti-vibration device 1A is mounted on the rear suspension 30 (see Figure 1A ) of the trailing arm 34 (refer to Figure 1A ), the main liquid chamber 21a is formed into a pair by sandwiching a partition wall 72a2 (first partition wall) extending in the up-down direction.

[0205] Furthermore, a pair of adjacent liquid chambers 21 b are formed so as to sandwich a partition wall 72 a 3 (second partition wall) extending in a direction intersecting the extending direction of the partition wall 72 a 2 (first partition wall) when viewed from the axial direction of the inner tube 3 .

[0206] On the other hand, Figure 10B As shown, the common portion 15b of the first liquid chamber 15 and the adjacent liquid chamber 21b (see Figure 10A ) are correspondingly provided above and below the active vibration isolation device 1A.

[0207] Furthermore, the hole portion 15a of the first liquid chamber 15 and the partition wall 72a3 (see Figure 10A ) is correspondingly provided in the active vibration isolation device 1A.

[0208] And, as Figure 10A As shown, the partition wall 72 a 2 (first partition wall) and the partition wall 72 a 3 (second partition wall) are connected to each other in the axial direction of the inner tube 3 .

[0209] That is to say, if Figure 10B As shown, it is mounted on the rear suspension 30 (refer to Figure 1A ) of the active vibration isolation device 1A, a pair of holes 15a are provided at positions 90 degrees out of phase with respect to the common portion 15b of the first liquid chamber 15, which is provided with a pair of upper and lower portions. In other words, the pair of holes 15a are arranged so as to face each other in the horizontal plane.

[0210] According to this active vibration isolation device 1A, the positions of the main liquid chamber 21a and the adjacent liquid chamber 21b are offset so that a pair of hole portions 15a are arranged relative to each other in the horizontal plane. Therefore, even when the magnetic powder of the magnetic viscoelastic fluid 20b is settled to the bottom in the vertical direction, the rigidity can be made variable.

Claims

1. An active vibration isolation device comprising: outer cylinder; an inner cylinder disposed on the inner circumference of the outer cylinder; a magnetic field generating unit for generating a magnetic field; a magnetic body forming a magnetic circuit based on the magnetic field; a first liquid chamber filled with a magneto-viscoelastic fluid; and a second liquid chamber adjacent to the first liquid chamber and filled with liquid, The active vibration isolation device is characterized in that: The magnetic field generating portion, the magnetic body, the first liquid chamber, and the second liquid chamber are provided between the inner tube and the outer tube in a radial direction. The first liquid chamber and the second liquid chamber are separated by a flexible member. The flexible member extends in the axial direction of the inner cylinder. A portion of the first liquid chamber forms a flow path of the magneto-viscoelastic fluid located on the magnetic path.

2. The active vibration isolation device according to claim 1, wherein: The flexible member is held by a cage located radially outward and the magnetic body located radially inward relative to the cage. The elastic body is connected to the cage box but not to the magnetic body.

3. The active vibration isolation device according to claim 2, wherein: The outer cylinder is processed to be reduced in diameter radially inward in a state where the cage is located inside.

4. The active vibration isolation device according to claim 3, wherein: The cage is formed only of a cylindrical portion extending along the outer cylinder.

5. The active vibration isolation device according to claim 2, wherein: The second liquid chamber includes an adjacent liquid chamber located radially outward of the flexible member and a main liquid chamber located on the opposite side of the adjacent liquid chamber across the elastic body in the axial direction. A connecting passage is provided between the cage box and the outer tube, connecting the main liquid chamber and the adjacent liquid chamber.

6. The active vibration isolation device according to claim 5, wherein: Active anti-vibration devices are bushings that connect the trailing arms to the vehicle body. The main liquid chamber is formed with a pair of first partition walls extending in the vertical direction sandwiched therebetween. The adjacent liquid chambers are formed as a pair with a second partition wall extending in a direction intersecting with the extending direction of the first partition wall when viewed from the axial direction. The first liquid chamber and the adjacent liquid chamber are arranged correspondingly up and down, The hole portion of the first liquid chamber is provided at a position corresponding to the second partition wall.

7. The active vibration isolation device according to claim 6, wherein: The connecting passage is set so that the resistance of the liquid when flowing through the connecting passage is smaller than the cross-sectional area of ​​the resistance when the magnetic viscoelastic fluid flows through the hole portion in a state where no magnetic field from the magnetic field generating unit acts.

8. The active vibration isolation device according to claim 2, wherein: The first liquid chamber is provided between the flexible member and the magnetic body. The second liquid chamber is provided between the flexible member and the outer tube.

9. A method for manufacturing an active vibration isolation device, characterized in that: The method for manufacturing the active vibration isolation device according to claim 1 comprises the following steps: a manufacturing step of a second liquid chamber forming portion, wherein the elastic body is integrally formed on the outer surface of the inner tube to form the second liquid chamber; a manufacturing step of the first liquid chamber forming portion, comprising combining the magnetic field generating portion, the magnetic body, and the flexible member in a liquid substance composed of the magnetic viscoelastic fluid to form the first liquid chamber filled with the magnetic viscoelastic fluid; a manufacturing step of assembling the first liquid chamber forming portion and the second liquid chamber forming portion so that the first liquid chamber and the second liquid chamber are separated by the flexible member extending in the axial direction of the inner tube and supported by the magnetic body, and the magnetic body and the inner tube are connected by the elastic body; and The fixing step includes inserting the assembly into the inner side of the outer tube in a liquid substance composed of the liquid so that the second liquid chamber is filled with the liquid, and fixing the assembly in the outer tube.

10. The method for manufacturing an active vibration isolation device according to claim 9, wherein: The step of fixing the assembly in the outer cylinder further includes a step of reducing the diameter of the outer cylinder toward the radial inner side.

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