JPS591829A - Liquid-enclosing vibration-proof device - Google Patents

Abstract

PURPOSE:To prevent the wide-range transmission of vibration in a device to be used for the mount of an engine by keeping a dynamic spring constant and a damping coefficient together at a high level in the vibration-damping area of low frequency, and at a low level in the vibration-proof area of high frequency. CONSTITUTION:On the basis of the output signal of a control device 12 receiving the signal of the relative displacement between an engine and a car body, a change-over switch 11 switches over a battery 10 connected to a coil 9 between positive and negative poles. In the vibration-damping area of low frequency, an actuator 14 composed of a permanent magnet is moved downward by the coil 9 when an elastic wall 1 is contracted, and upward when extended for increasing the pressure difference between fluid chambers A and B to increase the effect of damping. In the vibration-proof are of high frequency, the actuator 14 is moved oppositely to the above, and the pressure difference between fluid chambers A and B is reduced to reduce the effect of damping.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a vibration isolating device for use in a vehicle engine mount, which has first and second fluid chambers independent of each other and made of a rubber elastic wall, and is not subject to vibrations. The present invention relates to a liquid-filled vibration isolating device that damps vibrations by causing the sealed liquid to flow through a throttle hole formed in a partition between the two fluid chambers when the two fluid chambers are deformed.

The resonant frequency of the engine is usually between 10 Hz and 20 H.
It is in the low frequency range of about Z, and engine vibration is greatest at low speeds. In order to reduce the transmission of this low frequency vibration to the vehicle body and improve ride comfort, the vibration isolator needs to have a large damping coefficient in the low frequency range, that is, the vibration damping region. Furthermore, in order to prevent low-frequency vehicle body vibrations received from the road surface while driving from being transmitted to the engine, it is better to have a large damping coefficient in the damping region. For the same purpose, it is also necessary to increase the spring constant of the device in the damping region.

Engine vibrations during high-speed rotation are small, but since these high-frequency vibrations are in the audible range, when the vibrations are transmitted to the car body, the noise inside the car increases. In order to prevent the transmission of vibrations in this high frequency range, that is, the vibration isolation region, it is necessary to reduce the damping coefficient in the vibration isolation region of the vibration isolator. For the same purpose, it is also necessary to reduce the spring constant of the device in the vibration isolation area.

Here, a conventional liquid-filled vibration isolator is shown in FIG.

In the conventional example shown in the figure, l is a thick rubber elastic wall that constitutes the chamber wall of the first fluid chamber A and receives the load of the engine. This rubber elastic wall 1 has a truncated conical outer shape,
A conical recess is formed in its upper surface. The wall thickness gradually decreases upward. Further, a through hole 2 is formed in the rubber elastic body wall 1 and serves as a restricting hole along an axis connecting the apex of the recess and the center of the lower surface.

An upper plate 3 is provided on the upper part of the rubber elastic wall 1 in which a recess is formed so as to cover the recess, and a bolt 31 is provided protruding from the center of the upper plate 3. The engine body (not shown) is fixed to the device using this port 31. On the other hand, a bottom plate 4 is joined to the bottom surface of the rubber elastic body wall 1, and a through hole 41 is provided in the center thereof, which matches the aperture hole 2 described above.

6 is a rubber elastic sheet which can be deformed into a dome shape to increase its volume. A second fluid chamber B is formed by the elastic sheet 6 and the bottom plate 4.

A stopper member 5 is mounted in contact with the upper plate 3.

Both left and right ends of the stopper member 5 are bent downward to form a vertical portion 51.
The lower end faces the upper surface of the bottom plate 4 covered with a rubber elastic body at a predetermined interval, and comes into contact with the top surface of the bottom plate 4 when the rubber elastic body wall 1 is deformed beyond a set range. acts as a stopper. A hole 52 for passing the bolt 3 is formed in the center of the stopper member 5.

Reference numeral 7 denotes a protective cover, the central part of which has a dome shape that covers the chamber wall of the second fluid chamber B and the rubber elastic sheet 6, and the peripheral part of which is formed to cover the bottom plate 4. Then, the poles 41a and 41b are set up in advance and are in close contact with the bottom plate 4.

This device is fixed to the vehicle body using the above-mentioned ports 41a and 41b.

In the saliva-filled vibration isolator configured as described above and supporting the engine, when the engine vibrates, the first fluid chamber A
The rubber elastic wall l forming the chamber wall is elastically deformed. As a result, the volume of the first fluid chamber A changes and the hydraulic pressure changes, and the sealed liquid flows between the two fluid chambers A and B through the throttle hole 2.

Due to the flow resistance at this time, a large attenuation coefficient can be obtained in the low frequency droop control region, as shown by the line in FIG. However, in this structure, as shown by the line in FIG. 6, the dynamic spring constant increases rapidly in the vibration isolation region, which is a high frequency region.

It is an object of the present invention to solve the above-mentioned problems of the conventional device, and to provide a vibration isolator in which both the dynamic spring constant and the damping coefficient are large in the vibration damping region, and the dynamic spring constant and the damping coefficient are both small in the vibration damping region. A part of the upper plate 3 forming the chamber wall of the first fluid chamber A of the vibration isolator is formed into a bellows which is expandable and contractible and whose volume is variable, and an actuator such as a permanent magnet attached to the bellows is used. The above object is achieved by applying a magnetic field to actuate the bellows to increase the absolute value of the internal pressure of the first fluid chamber A in the vibration damping area, and vice versa in the vibration isolation area. It is.

FIG. 2 shows a first embodiment of the present invention, the basic structure of which is the same as the conventional device. A hole is provided in the center of the upper plate 3, and one open portion of the bellows 13 is connected to this hole.

The actuator 14 has disks with different diameters formed at both ends of the shaft, and the lower disk, which has a T-shaped cross section with the shaft vertical, seals the other opening of the bellows 13 and opens the first fluid chamber. A
It forms a movable wall. The upper disk is made of a permanent magnet with N and S poles formed on the upper and lower surfaces, respectively. A coil/I/9 is arranged concentrically around the axis of the actuator 14, and this coil/I/9 is attached to a button protruding from the upper plate 3.
) 31a, 311) VC fitted and fixed placket sa
, sb. The coil 7L'9 is also connected to the battery 7L'9 through the lead wires 16a and 16b and the changeover switch 11. The changeover switch 11 is configured to switch between positive and negative electrodes of the battery 10 connected to the coil 1v9 in response to an output signal from a control device 12 that receives a signal from a sensor (not shown) that detects relative displacement between the engine and the vehicle body due to vibrations. It has become.

The operation of the vibration isolator having the above configuration will be described below.

In the low frequency vibration damping region, when the vibration special plate 5 is pushed down and the elastic wall 1 contracts, the volume of the first fluid chamber A becomes smaller and its internal pressure increases, the changeover switch 11 A current is supplied from the battery 10 so that the magnetic field generated by the coil/L/9 forms N7 upward. Then, the actuator 14 moves downward, and the bellows 1 and 3 contract to reduce their volume, and the internal pressure of the first fluid chamber A is further increased. As a result, both fluid chambers A and B
As the pressure difference increases, the sealing liquid is forced to flow through the restrictor υ hole 2 at high speed, and as a result of the increased flow resistance, the damping effect increases. On the other hand, when the upper plate 3 is pulled upward and the elastic wall l is extended, the volume of the first fluid chamber A increases and the internal pressure of the first fluid chamber A decreases, the direction of the magnetic field generated by the coil 9 changes. is reversed to move actuator 14 upwards, extending bellows 13 and increasing its capacity. As a result, the internal pressure of the first fluid chamber A is further lowered, so that the pressure difference between the two fluid chambers A and B increases, the flow resistance increases, and the damping effect similarly increases.

In both of the above cases, since the absolute value of the internal pressure of the first fluid chamber A is large, the dynamic spring constant is large.@In the high frequency vibration isolation area, contrary to the vibration damping area, when the elastic wall 1 contracts, the actuator 14 is moved upward. Furthermore, when the elastic wall 1 is extended, the actuator 14 is moved downward. As a result, the pressure difference between the two fluid chambers A1B is reduced, the flow resistance is reduced, and the damping effect is reduced. In this case, since the absolute value of the internal pressure of the first fluid chamber A is small, the dynamic spring constant becomes small.

Dynamic spring constants and damping coefficients in both vibration damping and vibration isolation regions by the vibration isolating device of the present invention are shown by line M in FIGS. 6 and 7. According to this, both the dynamic spring constant and the damping coefficient are larger in the vibration damping region and smaller in the vibration isolating region than in the conventional device, and exhibit ideal characteristics as a vibration isolating device.

As described above, the liquid-filled vibration isolator of the present invention operates the bellows forming the movable wall of the first fluid chamber A so that the absolute value of the internal pressure of the first fluid chamber increases in the vibration damping region, thereby damping the vibration. Both the coefficient and the dynamic spring constant are increased, and the absolute value of the above-mentioned internal pressure is decreased in the vibration isolation region.By reducing both the damping coefficient and the dynamic spring constant, the It reduces vibration transmission to the vehicle body and exhibits excellent effects as a vibration isolator.

3 to 5 show second to fortieth embodiments of the vibration isolating device of the present invention, which are equipped with a sensor for detecting the relative position between the engine and the vehicle body due to vibration.

In FIG. 3, an electrode plate 17 having a punched hole corresponding to the aperture hole 2 is in contact with the bottom surface of the rubber elastic body 61, and an elastic body wall is placed between the electrode plate 17 and the bottom plate 4. A conductive rubber 18 having a constriction hole of the same shape as 1 is interposed. One ends of lead wires 15a and 15b are connected to the electrode plate 17 and the bottom plate 4 in order to measure the resistance change of the conductive rubber 18, and the other end of the lead wires reaches the controller 12.

In the above configuration, the elastic wall 1 is caused by vibration.
When the conductive rubber 18 is compressed, the conductive rubber 18 is also compressed, and its resistance value decreases.

When the elastic wall 1 is expanded, the conductive rubber 18 is also expanded and its resistance value increases. The controller 12 detects this change in resistance value and changes the direction of the magnetic field generated by the coil/L/9 via the changeover switch 11. The actuator 14 is actuated up and down to further increase the internal pressure and, conversely, to decrease the internal pressure to the first fluid chamber in the vibration isolation region. As a result, the damping coefficient and spring constant of this device both become large in the vibration damping region, and both become small in the vibration isolation region.

As described above, by incorporating a sensor that detects liquefaction in the relative distance between the engine and the vehicle body into the vibration isolating device of the present invention, in addition to its excellent performance, the entire device can be made compact.

FIG. 4 shows a third embodiment of the present invention in which a conductive rubber 18, which serves as a relative distance detection sensor, is formed on the outer periphery of the elastic wall l.

Since the conductive rubber 18 expands and contracts together with the rubber elastic wall 1, this change in resistance is measured by the lead wire 15a.

151) to the controller 12.

This embodiment also provides the same effects as the second embodiment.

FIG. 5 shows a fourth embodiment in which a piezoelectric sensor 19 is embedded in the lower part of the rubber elastic wall 1.

The piezoelectric sensor 19 detects stress changes in the elastic wall 1 due to expansion and contraction of the elastic wall 1 subjected to vibration, and the lead wire 15
The change in the generated voltage is input to the controller 12 via the terminals a and 115b. This embodiment also provides the same effects as the second embodiment.

As described above, the liquid-filled vibration isolator of the present invention detects changes in the relative position of the engine and the vehicle body due to engine vibration, and increases the internal pressure of the first fluid chamber of the vibration isolator in the vibration damping region, which is a low frequency range. In the vibration isolation frequency range, by operating the bellows that forms the movable wall of the first fluid chamber to lower the internal pressure of the fluid chamber, vibrations are transmitted to the vehicle body from low speed rotation to high speed rotation of the engine. This results in improved vehicle comfort and a significant improvement in driving performance.

[Brief explanation of the drawing]

FIG. 1 is an overall cross-sectional view of a conventional liquid-filled vibration isolator, FIGS. 2 to 5 are overall cross-sectional views of the vibration isolator according to the first to fourth embodiments of the present invention, and FIGS. Figure 7-1 is a diagram comparing the frequency characteristics of the dynamic spring constant and damping coefficient of the conventional vibration isolator and the vibration isolator of the present invention. A: First fluid chamber B: Second fluid chamber 1: Thick rubber elastic wall 2: Throttle hole 6: ... Rubber elastic sheet 9 ... Coil 1.0 ... Battery 11 ... Changeover switch 12 ... Controller 13 ... Bellows 14... Actuator 18... Conductive rubber (sensor) 19...
・Piezoelectric sensor (sensor) Figure 1

Claims (1)

[Claims] The first fluid chamber includes a first fluid chamber made of a thick rubber elastic wall, a second fluid chamber made of a thin rubber elastic wall, and a restriction hole that communicates between the two fluid chambers. The volumes of the two fluid chambers change due to the vibration of the supported body supported by the rubber elastic wall of the chamber, and the sealed liquid flows through the throttle hole. In the liquid-filled vibration isolator according to the present invention, a part of the chamber wall of the first fluid chamber is constituted by a bellows integrally provided with a permanent magnet, and the expansion and contraction of the bellows causes the first fluid chamber to open. A sensor is provided, the volume of which is variable, and which detects the relative displacement between the supported body and the supporting body due to vibration, and a magnetic field is applied to the signal of the sensor to cause the bellows to move into the first position in the vibration damping area. To encourage changes in the internal pressure of the fluid chamber,
A liquid-filled vibration isolator characterized in that the liquid-filled vibration isolator is actuated in the vibration isolator region to alleviate changes in the internal pressure of the first fluid chamber.