WO2004067992A1 - Liquid-seal vibration isolating device - Google Patents

Abstract

A suspension type liquid-seal vibration isolating device, wherein a support load is exerted to a second installation member (12) disposed inside a tubular first installation member (10) in such a direction that the member (12) is extracted in axial direction, a partition part (30) partitioning a lower side main liquid chamber (32) from an upper side auxiliary liquid chamber (34) is formed of a piston-like member (36) and a cylinder-like member (38) displaceable so as to vary the volumes of both liquid chambers (32) and (34) according to the elastic deformation of a vibration isolating base body (14) when vibration is applied thereto to develop a vibration isolating performance in a wide frequency range, MR fluid (40) having a viscosity varying according to the intensity of a magnetic field is sealingly held between both the piston-like member (36) and the cylinder-like member (38), and an electromagnet (46) capable of controlling the intensity of the magnetic field is installed in the piston-like member (36).

Description

 Description Liquid-filled anti-vibration device [Technical field]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid filled type vibration damping device mainly used for supporting a vibration body such as an automobile engine in a vibration damping manner.

 (Background technology)

 In general, a liquid-filled type vibration damping device includes two mounting brackets respectively attached to a support side of a vehicle body frame or the like and a vibration generator side of an engine or the like, a vibration isolating base made of a rubber material connecting the both mounting brackets, A main liquid chamber in which a part of the chamber wall is formed by the vibration isolating base; and a sub liquid chamber in which a part of the chamber wall is formed by the diaphragm and connected to the main liquid chamber through an orifice. The orifice is configured to perform a vibration damping function by the liquid flow effect between the two liquid chambers and the vibration damping effect of the vibration isolating base.

 Conventionally, there has been proposed such a liquid-filled type vibration damping device provided with a plurality of orifices so as to cope with vibrations in different frequency ranges such as shake vibration and idle vibration. For example, in the liquid-sealed type vibration damping device disclosed in Japanese Patent Application Laid-Open No. 2001-20992, a main liquid chamber and a sub liquid chamber are provided in a partition section that separates the main liquid chamber and the sub liquid chamber. A first orifice connecting the chambers is provided, and a second sub-liquid chamber and a second orifice communicating with the second sub-liquid chamber are provided. The first orifice absorbs, for example, shake vibration, and the second orifice, for example, absorbs shake vibration. It is configured to absorb idle vibration.

 However, in recent automobiles, the frequency range of idle vibration tends to be lower, and the difference from the frequency range of shake vibration is becoming smaller.Therefore, simply providing multiple orifices as described above is not sufficient. However, each orifice has a limit to effectively absorb each vibration.

On the other hand, liquid-filled vibration isolators that can absorb fluctuations in the liquid pressure in the main liquid chamber due to the effect of the liquid flowing through the orifice against vibrations in the low frequency range. However, for vibrations in the high frequency range, the state is the same as when the orifice is closed, so that fluctuations in hydraulic pressure in the main fluid chamber cannot be absorbed, and therefore vibrations in the high frequency range are good. There is a problem that it is not possible to secure an excellent vibration isolation performance.

 In order to solve such a problem, Japanese Patent Publication No. 2002-2609691 discloses a vibration isolator as shown in FIG. In this vibration isolator, a cylindrical lower mounting bracket 101 and an upper mounting bracket 102 arranged on the axis thereof are connected via a vibration isolating base 103 to form a lower mounting bracket. A diaphragm 104 is provided at the lower side of 101, and a liquid chamber between the vibration-proof base 103 and the upper main liquid chamber 106 and a lower auxiliary liquid chamber 1 are separated by a partition 105. And the two liquid chambers 106 and 107 are connected by an orifice 108 so that a supporting load is applied in the direction in which the main liquid chamber 106 is compressed. It is a vibration isolator. The partition 105 is configured to be displaceable in a direction in which the volumes of the upper and lower liquid chambers 106 and 107 are relatively variable, and the ease of displacement of the partition 105 is adjusted. In order to achieve this, a flow path 109 that holds the MR fluid whose viscosity can be increased or decreased according to the magnetic field strength, and an electromagnet 110 that can control the magnetic field strength are provided. By controlling the dynamic range, the dynamic spring constant of the partition portion 105 can be made variable so that vibration-proof performance against vibration in a wide frequency range can be exhibited.

In this anti-vibration device, the electromagnet 110 is integrated with the partition portion 105 to reduce the overall size of the device. In this way, the partition portion 105 is provided with the electromagnet 110. In this case, it is necessary to devise a way to draw out the lead wire 111 for the electromagnet 110 without passing through the inside of the auxiliary liquid chamber 107. For this reason, an opening is provided in the center of the diaphragm 104, the opening periphery 104A is connected to the lower surface of the partition 105, and the lead wire 111 is drawn out from the inside of the connection. Thus, the lead wire 111 is connected without passing through the inside of the auxiliary liquid chamber 107. However, when the central portion of the diaphragm 104 is connected to the partition portion 105 in this way, it is difficult to secure a radius allowance for the diaphragm 104. In order to secure a sufficient radius allowance, if the diaphragm 104 is formed in a folded shape in a bellows cross-section as shown by a two-dot chain line X in FIG. Excessive downward displacement of 102 Occasionally, there is a concern that the middle bent portion 104B may be inverted downward as indicated by the two-dot chain line Y, thereby impairing the durability of the diaphragm.

 [Disclosure of the Invention]

 The present invention has been made in view of the above points, and provides a liquid-sealed type vibration damping device that can exhibit vibration damping performance in a wide frequency range without impairing the durability of the diaphragm. The purpose is to:

 The liquid-filled type vibration damping device of the present invention includes: a first cylindrical mounting member; a second mounting member disposed inside the first mounting member; and a second mounting member interposed between the mounting members. A suspension type vibration isolating base comprising a rubber material for joining members, wherein a supporting load is applied in a direction in which the second mounting member is pulled out in the axial direction from the first mounting member. An apparatus, wherein a diaphragm is attached to the first mounting member so as to face the vibration-proof substrate, and a liquid sealing chamber is provided between the vibration-proof substrate and the diaphragm inside the first mounting member. The enclosing chamber is partitioned by a partition into a main liquid chamber on the vibration-isolating base side and a sub-liquid chamber on the diaphragm side, and both liquid chambers are connected via an orifice. The volume of both liquid chambers changes in a direction that can be relatively varied due to the elastic deformation of the vibration base. It consists of a piston-like member and a cylinder-like member surrounding the outer periphery of the piston-like member. The MR fluid whose viscosity changes according to the magnetic field strength is sealed between the piston-like member and the cylinder-like member in a flowable state. An MR flow path for holding is formed, and an electromagnet capable of controlling a magnetic field strength for forming a magnetic path crossing the MR flow path and changing the viscosity of the MR fluid is provided.

In the liquid filled type vibration damping device of the present invention, by turning on / off the energization of the electromagnet or controlling the energization current to increase or decrease the viscosity of the MR fluid, the piston-like member can be fixed at a fixed position, The volume of the liquid chamber and the sub-liquid chamber can be displaced in a direction that can be relatively varied, thereby controlling and controlling the dynamic panel constant and damping coefficient of the vibration isolator. The anti-vibration performance can be exhibited. In particular, according to the present invention, since the suspension type vibration damping device is used, the auxiliary liquid chamber on the diaphragm side expands when excessive displacement in the direction in which the supporting load exerts. It is not in the direction but in the contraction direction, so that it is possible to prevent reverse deformation of the middle bent portion of the diaphragm. Therefore, even if the electromagnet is fixedly supported on the piston-like member, an opening is provided in the center of the diaphragm, the periphery of the opening is connected to the biston-like member, and a lead wire for the electromagnet is drawn out from the inside of the connection portion. In this case, the durability of the diaphragm is not impaired.

 In the vibration damping device according to the present invention, the MR flow path is orthogonal to the displacement direction so that the flow path portions located parallel to each other along the displacement direction of the piston-like member and the flow path portions communicate with each other. Alternatively, it is preferably formed to have a crank-shaped cross section having a flow path portion that is located along a direction substantially orthogonal to and forms a transverse portion of the magnetic path. As described above, by adopting a configuration in which the flow path of the MR fluid has a crank-shaped cross section and the magnetic path crosses the flow path portion of the crank-shaped flow path that is substantially perpendicular to the displacement direction of the piston-like member, By increasing the viscosity of the MR fluid in the flow path corresponding to the crossing point of the magnetic path with the energization, the flow of the MR fluid can be blocked and the rigidity of the piston-like member can be rapidly increased. More specifically, for example, by forming the MR fluid flow path in a straight line and traversing a magnetic path through a part of the linear flow path, the MR fluid depends on the internal frictional force of the MR fluid, which increases in viscosity with energization. It is possible to increase the rate of change of the rigidity (spring constant) with respect to the flowing current, compared to the configuration that increases the rigidity. Therefore, the switching of the anti-vibration damping performance can be performed with less power consumption, thereby reducing the running cost and speeding up the switching.

 [Brief description of drawings]

 FIG. 1 is a longitudinal sectional view of a liquid filled type vibration damping device according to one embodiment of the present invention,

 Fig. 2 is an enlarged sectional view of the main part of the vibration isolator,

 FIG. 3 is a graph showing the relationship between the frequency, the dynamic spring constant and the damping coefficient of the vibration isolator, and FIG. 4 is a longitudinal sectional view of a conventional liquid-filled vibration isolator.

 [Best mode for carrying out the invention]

A liquid-filled type vibration damping device according to an embodiment of the present invention will be described with reference to FIGS. The anti-vibration device of the present embodiment is an engine mount that supports an automobile engine in an anti-vibration manner, and includes a cylindrical first metal mounting member 10 mounted on a vehicle body side and an inner axial center. A metal second mounting member 12 disposed on the engine side and mounted on the engine side, and a vibration-proof base 14 made of a rubber material interposed between the mounting members 10 and 12 and connecting the two. A suspension-type liquid-filled type vibration damping device comprising a second mounting member 12 and a supporting load applied in a direction in which the second mounting member 12 is drawn downward in the axial direction from the first mounting member 10.

 More specifically, the vibration-proof base 14 has a substantially truncated conical outer shape, and a substantially cylindrical second mounting member 12 is embedded so as to penetrate the center axis thereof. The outer periphery of the lower end is adhesively fixed to the inner peripheral surface of the lower part of the first mounting member 10 by vulcanization molding means. The first mounting member 10 is formed by fastening the upper cylindrical member 16 and the lower cylindrical member 18 at both ends by caulking, and the lower cylindrical member 18 is provided with the second mounting member 18. The member 12 is fitted into the cup-shaped bracket 22 having an opening 20 through which the member 12 is fitted.

 A flexible diaphragm 24 made of a thin rubber film is attached to the upper end opening of the first mounting member 10 so as to face the vibration isolating base 14. On the inner side of the first mounting member 10, a liquid filling chamber 26 sealed between the diaphragm 24 and the vibration-proof base 14 is formed, and the first mounting inside the liquid filling chamber 26 is formed. A disk-shaped partition portion 30 forming an orifice 28 on the outer periphery is liquid-tightly fitted on the inner periphery of the member 10. The liquid filling chamber 26 is vertically partitioned by the partition 30. A main liquid chamber 32 in which a part of the chamber wall is formed by the vibration-proof base 14 is provided on the vibration-proof base side of the partition 30, that is, on the lower side, and the diaphragm side of the partition 30, that is, On the upper side, a sub-liquid chamber 34 in which a part of the chamber wall is formed by a diaphragm 24 is provided, and the two liquid chambers 32 and 34 are connected via an orifice 28.

The partition part 30 is a disk that can be displaced in the direction in which the volumes of the two liquid chambers 32 and 34 are relatively varied in accordance with the elastic deformation of the vibration isolating base 14 when vibration is applied, that is, in the vertical direction (axial direction). A piston-like member 36 and an annular cylindrical member 38 surrounding the outer periphery thereof. The orifice 28 is formed on the outer periphery of the cylindrical member 38. I have. Between the piston-like member 36 and the cylinder-like member 38, there is formed an MR flow path 42 for hermetically holding the MR fluid 40, whose viscosity changes according to the magnetic field strength, in a flowable state. The MR flow path 42 is provided over the entire circumference by a thin cover rubber 44 attached between the outer peripheral portion of the piston-like member 36 and the inner peripheral portion of the cylindrical member 38.

 As shown in FIG. 2, the piston-like member 36 forms a magnetic path mp that traverses the MR flow path 42 and is an annular coil capable of controlling the magnetic field strength for changing the viscosity of the MR fluid 40. An electromagnet 46 composed of: a bobbin 48 holding the electromagnet 46; and a case 52 holding the bobbin 48 so as to be sandwiched vertically using fastening bolts 50. The outer peripheral surface of the case 52 is cut out over the entire circumference, whereby the piston-like member 36 is formed in a short cylindrical shape having a concave portion 54 extending in the circumferential direction on the outer peripheral surface.

 The cylindrical member 38 is made of a non-magnetic or weak magnetic material, and an inner peripheral surface thereof is provided with an annular yoke portion 56 made of a ferromagnetic material protruding toward the inner biston-shaped member 36. I have.

 The MR flow path 42 is composed of a pair of upper and lower vertical flow paths 42 A, 42 A and an intermediate vertical flow path located parallel to each other along the relative displacement direction of the piston-like member 36 and the cylinder-like member 38. The portion 42B and the pair of upper and lower vertical flow passages 42A, 42A and the intermediate flow passage portion 42B in a direction orthogonal or substantially orthogonal to the relative displacement direction so as to communicate with each other. It has a pair of upper and lower horizontal flow passage portions 42 C, 42 C located along the same, and is formed in a crank shape in cross section as a whole. More specifically, a passage 42 having a crank-shaped cross section is formed by inserting the inner peripheral end of the yoke portion 56 of the cylindrical member 38 into the concave portion 54 of the piston member 36 from the outside thereof. The vertical flow path portions 42A and 42A are provided on both upper and lower sides of the yoke portion 56, respectively, and an intermediate vertical flow path portion 42B is provided along the inner peripheral end of the yoke portion 56. Horizontal flow path portions 42 C and 42 C communicating these components are provided along the upper and lower surfaces of the yoke portion 56.

The electromagnet 46 crosses a pair of upper and lower horizontal flow paths 42 C and 42 C of the MR flow path. It is arranged inside the concave portion 54 of the biston-shaped member 36 so as to form a magnetic path mp as follows. A lead wire 58 is connected to the electromagnet 46, and the lead wire 58 is connected to the control unit 60. In detail, an opening is provided at the center of the diaphragm 24, the peripheral edge 24A of the opening is connected to the upper surface of the piston-like member 36, and the lead wire 58 is drawn out from the inside of the connecting portion. The lead wire 58 is connected without passing through the liquid chamber 34. The diaphragm 24 is formed in a bellows-like cross section having a middle bent portion 24B which is folded in a direction toward the partition portion 30, that is, downward so as to secure a bending allowance.

 Then, based on a signal from the control unit 60, by controlling the current supplied to the electromagnet 46, the magnetic field strength flowing in the magnetic path mp traversing the horizontal flow path portion 42C of the MR flow path is controlled. The viscosity of the MR fluid 40 can be increased or decreased by controlling the viscosity. The MR fluid 40 is a Bingham fluid in which ferromagnetic metal particles having a particle diameter of about 1 to 10 / m are dispersed in a high-concentration suspension. It has an operating temperature range of C and its viscosity changes according to the magnitude of the magnetic field strength. It is called a magnetorheological fluid or a magnetorheological fluid.

 In the vibration damping device of the present embodiment configured as described above, when the power to the electromagnet 46 is turned on, the viscosity of the MR fluid 40 increases, and the piston-like member 36 becomes hard to be displaced and is fixed at a fixed position. You. On the other hand, when the energization of the electromagnet 46 is turned off, the viscosity of the MR fluid 40 decreases, and the piston-like member 36 is easily displaced, and the displacement causes the main liquid chamber 32 and the sub liquid chamber 34 to move. Can be varied. Further, by adjusting the viscosity of the MR fluid 40 by controlling the energizing current, the vibration can be attenuated by the viscous effect of the MR fluid 40.

As shown in Fig. 3, when the power is turned off, the peak frequency of the damping coefficient (the resonance frequency of the orifice 28) shifts to a lower frequency than when the power is turned off. Also, when the power is turned off, the dynamic spring constant is lower in the high frequency range than when it is turned on. Therefore, it is preferable to control as follows using this phenomenon. First, it is assumed that the resonance frequency of the orifice 28 is 設定 Make settings so as to attenuate vibrations (for example, around 12 Hz) and idle vibrations (for example, 15 to 21012) when power is on. When the vehicle is idling, the power is turned on, and when the vehicle is running, the power is turned off. As a result, at idle, for example, idle vibration of 17 Hz can be attenuated by the orifice 28. In addition, by turning off the power during traveling, the resonance frequency of the orifice 28 decreases to about 12 Hz, so that the shake vibration can be attenuated.

Vibration damping effect can be exerted against vibrations in a high frequency range exceeding 20 Hz (for example, 40 to 300 Hz). By performing such control, it is possible to reduce the amount of electric power consumed while the vehicle is running, and to contribute to a reduction in fuel consumption of the entire vehicle.

 The control method is not limited to the above, and may be controlled, for example, as follows. Under the condition where vibrations in the low frequency range are applied, energization is turned on, the piston-like member 36 is fixed in place, and the orifice 28 is connected between the main liquid chamber 32 and the sub liquid chamber 34. The liquid is caused to flow to absorb fluctuations in the liquid pressure in the main liquid chamber 32, thereby attenuating vibration in the low frequency region. Then, under the condition where the vibration in the high frequency region acts, the energization is turned off, or the energization current is increased or decreased to adjust the magnitude of the magnetic field strength, thereby reducing the dynamic panel constant of the piston-like member 36. Makes it smaller than when energized, and exhibits a vibration proof effect against vibrations in the high frequency range.

 As described above, the liquid-filled type vibration damping device of the present embodiment can exhibit the vibration damping performance in a wide frequency range, but also has improved durability of the diaphragm 24. In other words, in such a suspension type vibration damping device, when the support load is excessively displaced in the direction in which the supporting load is exerted (the direction in which the second mounting member 12 moves downward, that is, the direction in which the main liquid chamber 32 expands), Sub liquid chamber 3 4 is not in the expansion direction, so the partition

No reverse deformation occurs in the middle bent portion 24 B of the diaphragm 24 protruding to the 30 side, and therefore, there is no problem in the durability of the diaphragm 24.

 [Industrial applicability]

According to the present invention, it is possible to cover a wide frequency range without deteriorating the durability of the diaphragm. Thus, a liquid-filled type vibration damping device capable of exhibiting vibration damping performance can be obtained.

Claims

A first mounting member having a cylindrical shape, a second mounting member disposed inside the first mounting member, and a rubber material interposed between the mounting members and connecting the two mounting members. A suspension-type vibration isolator including a vibration isolating base, wherein a supporting load is applied in a direction in which the second mounting member is pulled out in the axial direction from the first mounting member, wherein the vibration isolating base is provided. A diaphragm is attached to the first mounting member facing the first mounting member, a liquid sealing chamber is provided between the vibration-proof base and the diaphragm inside the first mounting member, and the liquid sealing chamber is separated by a partition. The liquid chamber is divided into a main liquid chamber on the side and a sub liquid chamber on the diaphragm side, and both liquid chambers are connected via an orifice.  The partition portion is composed of a piston-like member that can be displaced in a direction in which the volumes of the two liquid chambers can be relatively varied along with elastic deformation of the vibration-proof base when vibration is applied, and a cylinder-like member that surrounds the outer periphery thereof. , _  An MR flow path is formed between the piston-like member and the cylinder-shaped member, the MR flow path having a viscosity that changes according to the magnetic field strength, and hermetically holding the MR fluid in a flowable state, and a magnetic path traversing the MR flow path. And an electromagnet that can control the magnetic field strength to change the viscosity of the MR fluid  A liquid filled type vibration damping device characterized by the above-mentioned. The MR flow path is arranged along a direction orthogonal or substantially orthogonal to the displacement direction so that the flow path portions located parallel to each other along the displacement direction of the piston-like member and the flow path portions communicate with each other. 2. The liquid-filled type vibration damping device according to claim 1, wherein the device is formed in a crank-shaped cross section having a flow path portion that is positioned and forms a transverse portion of the magnetic path. 2. The liquid-filled type vibration damping device according to claim 1, wherein the electromagnet is fixedly supported by the piston-shaped member.