JPH04302729A - Mount for power unit - Google Patents

Abstract

PURPOSE:To provide a mount for power unit furnishing a damper means to attenuate the vibration of the power unit, which can suppress the vibration effectively to both a low-frequency vibration and a high-frequency vibration. CONSTITUTION:A fluid chamber in which a fluid is sealed is partitioned into a main chamber 12 and a sub-chamber 13, and a damper means is composed of a partition wall 11 furnishing a movable part 17, and a fluid passage 15 for damping provided to the partition wall 11. At the same time, a G sensor 18 to detect the acceleration of the power unit in the up and down direction, and an actuator 6 which consists of a piezoelectric element 5 to vibrate the movable part 17 are provided, and the actuator 6 is driven depending on the signal from the G sensor 18.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mount for a power unit that elastically supports the power unit with respect to a vehicle body and is provided with damper means for damping vibrations of the power unit by the flow of fluid sealed therein.

0002

2. Description of the Related Art In automobiles, a mounting device is disposed between the vehicle body and a power unit consisting of an engine, a transmission, etc. in order to suppress vibrations of the power unit or transmission of the vibrations to the vehicle body.
For example, according to Japanese Unexamined Patent Publication No. 59-23140, a vibration-proof rubber and a laminate of electrostrictive elements whose thickness changes when energized are arranged in series between the engine and the vehicle body. A mounting device (vibration absorption method) is disclosed that suppresses engine vibrations by causing vibrations to synchronize with engine vibrations and have an opposite phase. Further, as one type of this type of mounting device, a liquid-filled mounting device is known. This partitions a liquid chamber filled with liquid into a main chamber and a sub-chamber by a partition wall, and forms a liquid passage communicating with the main chamber and sub-chamber, so that when vibrations are transmitted from the power unit, The liquid is caused to flow between the main chamber and the auxiliary chamber through the liquid passage, and the damping force generated thereby suppresses vibrations of the power unit and transmission of the vibrations to the vehicle body.

0003

[Problems to be Solved by the Invention] However, in the liquid-filled mounting device as described above, when the frequency of vibration transmitted from the power unit is relatively low, it is necessary to The liquid flows between the chamber and the auxiliary chamber, which suppresses the vibrations of the power unit, but as the frequency of vibrations transmitted from the power unit increases, the flow between the main chamber and the auxiliary chamber increases. The flow of liquid between the
As a result, the damping force is significantly reduced, and the high frequency vibrations of the power unit are not suppressed and are transmitted to the vehicle body.

Therefore, the present invention provides a mount for a power unit that elastically supports the power unit with respect to the vehicle body and is equipped with a damper means that damps vibrations of the power unit by the flow of fluid sealed inside. It is an object of the present invention to provide a power unit mount that can effectively suppress both high-frequency vibrations and high-frequency vibrations.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the present invention is characterized by the following structure.

First, the invention according to claim 1 of the present application (hereinafter referred to as
The first invention) provides a mount for a power unit that elastically supports a power unit with respect to a vehicle body and is provided with a damper means that damps vibrations of the power unit by the flow of fluid sealed therein. an actuator made of a stack of piezoelectric elements whose plate thickness changes when energized and which is operated in synchronization with the power unit; a vibration detection means for detecting vibrations of the power unit; and a drive for the actuator based on a signal from the vibration detection means. The invention is characterized in that it is provided with a control means for controlling.

[0007] Furthermore, the invention according to claim 2 of the present application (hereinafter,
A second invention) provides a mount for a power unit that is equipped with a damper means for damping vibrations of the power unit by the flow of a fluid sealed therein, similar to the first invention, in which a liquid chamber filled with the liquid is the main part. an actuator that is connected via an elastic body to a partition wall that partitions a chamber and a sub-chamber, is actuated in synchronization with the vibrations of the power unit, and is made of a laminate of piezoelectric elements whose plate thickness changes when energized; The present invention is characterized in that it includes a vibration detection means for detecting vibration, and a control means for driving the actuator based on a signal from the vibration detection means.

Furthermore, the invention according to claim 3 of the present application (hereinafter,
A third invention) provides a power unit mount including a damper means for damping vibrations of the power unit by the flow of a fluid sealed therein, as in the first and second inventions. A movable member provided in the room, an actuator that is connected to the movable member and is a stack of piezoelectric elements that is activated in synchronization with the vibrations of the power unit and whose plate thickness changes when energized, and detects the vibrations of the power unit. The present invention is characterized in that it includes a vibration detection means for detecting vibration, and a control means for driving the actuator based on a signal from the vibration detection means.

[0009]

[Operation] In both the first and second inventions, when the entire power unit vibrates at low frequency with large amplitude during idling, etc., due to the damping force generated by the flow of liquid by the damper means of the power unit mount, Low frequency vibrations of the power unit and transmission of the vibrations to the vehicle body are effectively suppressed. Also,
When the power unit makes high-frequency slight vibrations during deceleration, etc., the actuator is vibrated in synchronization with the high-frequency vibrations of the power unit based on a signal from the vibration detection means that detects the vibrations of the power unit.
Fluid pressure fluctuations in the fluid chamber of the power unit mount are suppressed during high-frequency vibrations of the power unit, suppressing high-frequency minute vibrations of the power unit and transmission of those vibrations to the vehicle body, and reducing both low-frequency vibrations and high-frequency vibrations. will also be effectively suppressed.

According to the third aspect of the present invention, when the entire power unit vibrates at a large amplitude and low frequency during idling, etc., the damping force generated by the flow of liquid by the damper means of the power unit mount causes the power unit to This effectively suppresses low-frequency vibrations and transmission of such vibrations to the vehicle body, and when the power unit causes high-frequency slight vibrations during deceleration, etc., the vibration detection means for detecting the vibrations of the power unit Based on the signal, the movable member is vibrated via the actuator in synchronization with the high-frequency vibration of the power unit, and this suppresses fluid pressure fluctuations in the fluid chamber of the power unit mount during high-frequency vibration of the power unit, and suppresses the high-frequency vibration of the power unit. Vibrations and their transmission to the vehicle body are suppressed, and both low-frequency vibrations and high-frequency vibrations are effectively suppressed. In particular, according to the third invention, the movable member is driven by the actuator in synchronization with the high frequency vibration of the power unit, and the liquid actively flows in the liquid chamber, thereby preventing a decrease in damping force. As a result, high frequency vibrations of the power unit can be suppressed more effectively.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

As shown in FIGS. 1 and 2, a plurality of power unit mounts 3...3 are provided between a power unit 1 consisting of an engine, a transmission, etc., and a vehicle body side member 2.
is arranged, and this mount 3 has a rubber 4 as an elastic body integrally attached to the upper end of the upper casing 3a.
and an actuator 6 which is arranged in the lower casing 3b and is made of a stacked body of a large number of piezoelectric elements 5...5 whose plate thickness changes when energized. Mounting bolts 8 are integrally attached to the upper mounting member 7 fixed to the upper surface of the rubber 4, and mounting bolts 9 are integrally attached to the lower surface of the lower casing 3b.
, 9 to the mounting bracket 1a integral with the power unit 1 and the vehicle body side member 2 via nuts 8a, 9a, the power unit mount 3 is coupled to the vehicle body side member 2 and the power unit 1.

Further, a liquid chamber 10 filled with a predetermined liquid is formed below the rubber 4, and this liquid chamber 10 is located at the outer peripheral edge between the mating surfaces of the upper casing 3a and the lower casing 3b. is sandwiched therein, and is divided into an upper main chamber 12 and a lower sub-chamber 13 by a partition wall 11 whose inner peripheral edge is fixed to the outer surface of the casing 6a of the actuator 6, and the sub-chamber 13 is separated from the partition wall 11. and a bellows 14 made of rubber. Furthermore, the partition wall 11
A liquid passage 15 made of a ring-shaped body is formed on the lower surface of the partition wall 1, as shown in FIGS. 2 and 3.
A pair of communication holes 16a, 16b are formed in the main chamber 12 and the liquid passage 15, and liquid flows between the main chamber 12 and the sub chamber 13 through these communication holes 16a, 16b and the liquid passage 15. As a result, vibrations of the power unit 1 are damped. Further, a movable part 17 is connected to the partition wall 11, which is made up of a rubber 17a integrally fixed to the partition wall 11 and a plate member 17b connected to the rubber 17a, and an actuator 6 is connected to the plate member 17b. This actuator 6 is connected to each piezoelectric element 5...
By applying a predetermined voltage between the piezoelectric elements 5...5, the plate thickness of these piezoelectric elements 5...5 changes, and as a result, the movable part 17
is set to vibrate.

Furthermore, the mounting member 1a is provided with a G sensor 1 for detecting the vertical acceleration of the power unit 1 and detecting the vibration state of the power unit 1 based on this.
8 is attached.

As shown in FIG. 4, a control unit 19 is provided for controlling the operation of the actuator 6, and this control unit 19 has the following functions:
A signal from the G sensor 18, a signal from the rotation sensor 20 that detects the engine speed, and a signal from the temperature sensor 21 that detects the temperature around the location where the power unit mount 3 is installed are input, and The control unit 19 includes a high-pass processing section 22 that cuts signals indicating low-frequency vibrations from among the signals from the G sensor 18 and passes signals indicating high-frequency vibrations of a predetermined frequency or higher.
, the signal from the high-pass processing section 22 and each of the above-mentioned sensors 1
a calculation section 23 that receives signals from the temperature sensors 8 and 20 and calculates the output voltage to the actuator 6; and a temperature correction section that corrects the output voltage calculated by the calculation section 23 based on the signal from the temperature sensor 21. 24, and the operation of the actuator 6 is controlled by a control signal output from the temperature correction section 24.

Next, the control operation of the actuator 6 by the control unit 19 will be explained based on the flow chart shown in FIG. vertical acceleration of
That is, a signal indicating vertical vibration is subjected to high-pass processing, and in step S2, a gain value of the output voltage to the actuator 6, that is, an acceleration gain KG, which is set based on the high-pass processed signal from the G sensor 18, is calculated. This acceleration gain KG is calculated using the vertical acceleration (frequency) G of the power unit 1 detected by the G sensor 11 and the vehicle speed v detected by the rotation sensor 20 as parameters.
The characteristics shown in FIG. 6 are set in advance, and a plurality of acceleration gains KG are set so that the gain value increases as the vehicle speed v increases, and these are recorded in the control unit 19 as a map. There is. Thereafter, in step S3, the temperature correction section 24 corrects the acceleration gain KG set in step S2. This is because, as shown in FIG. 7, the rate of change in the plate thickness of the piezoelectric element 5 that constitutes the actuator 6, that is, the strain rate, is affected by temperature. Therefore, the strain rate remains constant regardless of the temperature. The applied voltage is corrected according to the characteristics shown in FIG. 8 so that Then, in step S4, a control signal (applied voltage) that has been temperature-corrected so as to have a predetermined gain value is output to the actuator 6.

Therefore, when the entire power unit vibrates with large amplitude and low frequency, such as during idling, the liquid flows between the main chamber 12 and the auxiliary chamber 13 through the liquid passage 15, which causes vibrations to occur. The damping force effectively suppresses low frequency vibrations of the power unit 1 and transmission of the vibrations to the vehicle body. In addition, when the power unit 1 causes high-frequency slight vibrations during deceleration, etc., the actuator 6 is activated based on a signal obtained by high-pass processing the signal from the G sensor 18 that detects the vertical acceleration (vertical vibration) of the power unit 1. Through the movable part 17
is vibrated in synchronization with the high-frequency vibration of the power unit, thereby suppressing fluid pressure fluctuations in the fluid chamber 10 in the power unit mount 3 during high-frequency vibration of the power unit 1, thereby suppressing high-frequency micro-vibration or The transmission of the vibration to the vehicle body is suppressed. In this way, both low frequency vibrations and high frequency vibrations are effectively suppressed.

Furthermore, the vibration load of the power unit 1 does not directly act on the actuator 6 made of the piezoelectric element 5, which improves the accuracy of control by the actuator 6 and allows the actuator 6 to be made smaller. Therefore, the entire power unit mount 3 can be configured more compactly. Moreover, as described above, low-frequency vibrations are effectively suppressed by the damping effect caused by the flow of the liquid, and high-frequency vibrations are effectively suppressed by the actuator 6 and the movable part 17, which are made of a stack of piezoelectric elements 5. Therefore, compared to the case where low frequency vibrations and high frequency vibrations are suppressed using, for example, a hydraulic control device that actively supplies and discharges liquid from the outside to the liquid chamber 10, the power unit mount 3 as a whole is can be configured simply and compactly.

9 to 11 show other embodiments of the power unit mount. The mount 33 shown in FIG. 9 includes a ring-shaped rubber 34 as an elastic body and a lower casing 33b. The actuator 36 is made of a laminate of a large number of piezoelectric elements 35...35 whose plate thickness changes when energized. A mounting bolt 38 is attached to the upper mounting member 37 fixed to the upper surface of the rubber 34.
However, mounting bolts 39 are each integrally attached to the lower surface of the lower casing 33b, and these mounting bolts 38, 39 are attached to a mounting bracket 31a integrated with the power unit and a nut 38 to the vehicle body side member 32.
a, 39a, the power unit mount 33 is connected to the vehicle body side member 32 and the mounting bracket 3.
1a.

Further, a liquid chamber 40 in which a predetermined liquid is sealed is formed inside the rubber 34, and this liquid chamber 40 is located between the mating surfaces of the upper mounting member 37 and the rubber 34 at the outer peripheral edge thereof. It is divided into a main chamber 42 and a sub-chamber 43 by a partition wall 41 having a portion sandwiched therebetween, and the sub-chamber 43 is formed by the partition wall 41 and a bellows 44 made of rubber. Further, in the center of the partition wall 41, an orifice 4 having a predetermined diameter is provided.
5 is formed, and liquid flows between the main chamber 42 and the sub chamber 43 through this orifice 45, thereby damping vibrations of the power unit. Further, an actuator 36 is connected to a partition wall 47 constituting the bottom surface of the main chamber 42, and this actuator 36 is driven and controlled in the same manner as in the first embodiment, and a predetermined distance is set between each piezoelectric element 35...35. By applying a voltage, the plate thicknesses of these piezoelectric elements 35...35 change, thereby causing the partition wall 47 to vibrate.

Therefore, when the entire power unit vibrates with large amplitude and low frequency, such as during idling, liquid flows between the main chamber 42 and the auxiliary chamber 43 through the orifice 45, which causes vibrations to occur. The damping force effectively suppresses low frequency vibrations of the power unit and transmission of the vibrations to the vehicle body. Furthermore, when the power unit undergoes high-frequency slight vibrations during deceleration, etc., the partition wall 47 is vibrated via the actuator 36 in synchronization with the high-frequency vibrations of the power unit, thereby causing the power unit mount 33 to vibrate during high-frequency vibrations of the power unit. Fluctuations in the fluid pressure within the fluid chamber 40 are reduced, suppressing high-frequency micro-vibrations of the power unit and transmission of those vibrations to the vehicle body, which is effective against both low-frequency vibrations and high-frequency vibrations. can be suppressed to

Furthermore, the vibration load of the power unit does not directly act on the actuator 36 made of the piezoelectric element 35, which improves the accuracy of control by the actuator 36 and allows the actuator 36 to be made smaller. The power unit mount 3
3 can be configured more compactly. Furthermore, as described above, low-frequency vibrations are effectively suppressed by the damping effect accompanying the flow of liquid, and high-frequency vibrations are effectively suppressed by the actuator 36 made of a stack of piezoelectric elements 35. Compared to the case where low-frequency vibrations and high-frequency vibrations are suppressed using a hydraulic control device or the like that actively supplies and discharges liquid from the outside to the liquid chamber 40, the entire power unit mount 33 can be simplified and It can be configured compactly.

The mount 53 shown in FIG. 10 also includes a ring-shaped rubber 54 as an elastic body and an upper casing 5.
3a, and an actuator 56 made of a laminate of a large number of piezoelectric elements 55...55 whose plate thickness changes when energized. Mounting bolts 58 are integrally attached to the upper surface of the upper casing 54a, and mounting bolts 59 are integrally attached to the lower surface of the lower casing 53b. The power unit mount 53 is coupled to the vehicle body side member 52 and the mounting bracket 51a by fastening to the bracket 51a and the vehicle body side member 52 via nuts 58a, 59a.

A liquid chamber 60 filled with a predetermined liquid is formed inside the rubber 54. The main chamber 62 is separated by the partition wall 61 in which the
and a subchamber 63, and the subchamber 63 is formed by the partition wall 61 and a bellows 64 made of rubber. Furthermore, an orifice 65 having a predetermined diameter is formed in the center of the partition wall 61, and liquid flows between the main chamber 62 and the sub chamber 63 through this orifice 65, thereby The vibration of the power unit is damped. In addition, an actuator 56 is provided in the main chamber 62.
A movable member 67 is connected to and driven by the actuator 56, and the actuator 56 is driven and controlled in the same manner as in the first embodiment, and a predetermined voltage is applied between each piezoelectric element 55...55. By applying this, the plate thickness of these piezoelectric elements 55...55 changes, and as a result, the movable member 47 is vibrated.

Therefore, when the entire power unit vibrates with large amplitude and low frequency, such as during idling, liquid flows between the main chamber 62 and the sub chamber 63 through the orifice 65, which causes vibrations to occur. The damping force effectively suppresses low frequency vibrations of the power unit and transmission of the vibrations to the vehicle body. Further, when the power unit undergoes high-frequency slight vibrations during deceleration, etc., the movable member 67 is vibrated within the main chamber 62 in synchronization with the high-frequency vibrations of the power unit via the actuator 56.
As a result, fluid pressure fluctuations in the fluid chamber 60 in the power unit mount 53 are suppressed during high-frequency vibrations of the power unit, and the fluid actively flows in the main chamber 62 as the movable member 67 vibrates. As a result, transmission of high-frequency micro-vibrations of the power unit to the vehicle body is suppressed, and both low-frequency vibrations and high-frequency vibrations can be effectively suppressed.

Furthermore, the vibration load of the power unit does not directly act on the actuator 56 made of the piezoelectric element 55, which improves the accuracy of control by the actuator 56 and allows the actuator 56 to be made smaller. Mount 5 for the power unit
3 can be configured more compactly. Furthermore, as described above, low frequency vibrations are effectively suppressed by the damping effect accompanying the flow of the liquid, and high frequency vibrations are effectively suppressed by the actuator 56 made of a stack of piezoelectric elements 55. Compared to the case where low-frequency vibrations and high-frequency vibrations are suppressed using a hydraulic control device or the like that actively supplies and discharges liquid from the outside to the liquid chamber 60, the entire power unit mount 53 can be simplified and It can be configured compactly.

The mount 73 shown in FIG. 11 also includes a ring-shaped rubber 74 as an elastic body and an upper casing 7.
3a, and an actuator 76 made of a laminate of a large number of piezoelectric elements 75...75 whose plate thickness changes when energized. Mounting bolts 78 are integrally attached to the upper surface of the upper casing 73a, and mounting bolts 79 are integrally attached to the lower surface of the lower casing 73b. The power unit mount 73 is coupled to the vehicle body side member 72 and the mounting bracket 71a by fastening to the bracket 71a and the vehicle body side member 72 via nuts 78a, 79a.

A liquid chamber 80 filled with a predetermined liquid is formed inside the rubber 74, and the bottom surface of the liquid chamber 80 is formed by a bellows 84 made of rubber. Further, a movable member 87 connected to and driven by the actuator 76 is provided in the liquid chamber 80, and the actuator 76 is drive-controlled in the same manner as in the first embodiment. By applying a predetermined voltage between the piezoelectric elements 75...75, the plate thicknesses of the piezoelectric elements 75...75 change, thereby causing the movable member 87 to vibrate.

Therefore, when the entire power unit vibrates with large amplitude and low frequency during idling, etc., the liquid in the liquid chamber 80 flows, and the damping force generated thereby causes the low frequency vibration of the power unit or its vibration. transmission to the vehicle body is effectively suppressed. Furthermore, when the power unit undergoes high-frequency slight vibrations during deceleration, etc., the movable member 87 is vibrated within the liquid chamber 80 in synchronization with the high-frequency vibrations of the power unit via the actuator 76. Fluctuations in the fluid pressure in the fluid chamber 80 in the power unit mount 73 are suppressed, and the fluid actively flows in the fluid chamber 80 due to the vibration of the movable member 87, thereby reducing high-frequency micro-vibration of the power unit. The transmission of the vibrations to the vehicle body is thereby suppressed, and both low-frequency vibrations and high-frequency vibrations can be effectively suppressed.

Furthermore, the vibration load of the power unit does not directly act on the actuator 76 made of the piezoelectric element 75, which improves the precision of control by the actuator 76 and allows the actuator 76 to be made smaller. The power unit mount 7
3 can be configured more compactly. Moreover, as described above, low-frequency vibrations are effectively suppressed by the damping effect accompanying the liquid flow, and high-frequency vibrations are effectively suppressed by the actuator 76 made of a stack of piezoelectric elements 75. Compared to the case where low-frequency vibrations and high-frequency vibrations are suppressed using a hydraulic control device or the like that actively supplies and discharges liquid from the outside to the liquid chamber 80, the entire power unit mount 83 can be simplified and It can be configured compactly.

[0031]

As described above, in both the first and second inventions, when the entire power unit vibrates with large amplitude and low frequency during idling, etc., the damper means of the power unit mount prevents the liquid from flowing. The generated damping force effectively suppresses low frequency vibrations of the power unit and transmission of the vibrations to the vehicle body. Furthermore, when the power unit undergoes high-frequency slight vibrations during deceleration, etc., the actuator is vibrated in synchronization with the high-frequency vibrations of the power unit based on a signal from a vibration detection means that detects vibrations of the power unit. Fluid pressure fluctuations in the fluid chamber of the power unit mount are suppressed during high-frequency vibrations, suppressing high-frequency minute vibrations of the power unit and transmission of those vibrations to the vehicle body, and reducing both low-frequency vibrations and high-frequency vibrations. will be effectively suppressed.

Further, according to the third invention, when the entire power unit vibrates at low frequency with a large amplitude during idling, etc., the damping force generated by the flow of liquid by the damper means of the power unit mount causes the power unit to vibrate at low frequencies. Low-frequency vibrations and their transmission to the vehicle body are effectively suppressed, and when the power unit causes high-frequency slight vibrations during deceleration, etc., the vibration detection means for detecting the vibrations of the power unit is suppressed. Based on the signal, the movable member is vibrated via the actuator in synchronization with the high-frequency vibration of the power unit, thereby suppressing fluid pressure fluctuations in the fluid chamber of the power unit mount during high-frequency vibration of the power unit, and suppressing high-frequency minute vibrations of the power unit. This means that the transmission of the vibrations to the vehicle body is suppressed, and both low-frequency vibrations and high-frequency vibrations are effectively suppressed. In particular, according to the third invention, the movable member is driven by the actuator in synchronization with the high frequency vibration of the power unit, and the liquid actively flows in the liquid chamber, thereby preventing a decrease in damping force. As a result, high frequency vibrations of the power unit can be suppressed more effectively.

[Brief explanation of drawings]

FIG. 1 is an overall front view showing the arrangement of a power unit mounting device.

[Fig. 2] An enlarged vertical cross-sectional view of the power unit mount.

FIG. 3 is a sectional view taken along the line A--I in FIG. 2;

FIG. 4 is an overall system diagram of the control system of the actuator that constitutes the power unit mount.

FIG. 5 is a flowchart showing the control operation of the actuator by the control unit.

FIG. 6 is a map showing the characteristics of acceleration gain.

[Figure 7] Strain characteristic diagram of the piezoelectric element.

FIG. 8 is a graph showing the output characteristics of the voltage applied to the piezoelectric element.

FIG. 9 is an enlarged vertical cross-sectional view of a power unit mount according to a second embodiment.

FIG. 10 is an enlarged vertical cross-sectional view of a power unit mount according to a third embodiment.

FIG. 11 is an enlarged vertical cross-sectional view of a power unit mount according to a fourth embodiment.

[Explanation of symbols]

1 Power unit 3, 33, 53, 73 Power unit mount 5, 35, 55, 75 Piezoelectric element 6
, 36, 56, 76 actuator 10, 40
,60,80 Liquid chamber

Claims (3)

[Claims] 1. A mount for a power unit, comprising a damper means for resiliently supporting a power unit with respect to a vehicle body and damping vibrations of the power unit by the flow of fluid sealed inside, the mount for a power unit elastically supporting the power unit against a vehicle body, and comprising damper means for damping vibrations of the power unit by the flow of fluid sealed inside. an actuator made of a stack of piezoelectric elements whose plate thickness changes when energized and which is operated in synchronization with the power unit; a vibration detection means for detecting vibrations of the power unit; and a drive for the actuator based on a signal from the vibration detection means. A mount for a power unit, characterized in that a control means for controlling the power unit is provided. 2. A power unit mount comprising damper means for elastically supporting a power unit with respect to a vehicle body and damping vibrations of the power unit by the flow of a fluid sealed therein, wherein the liquid is sealed The piezoelectric element is connected via an elastic body to a partition wall that divides the liquid chamber into a main chamber and an auxiliary chamber, and is actuated in synchronization with the vibration of the power unit, and the thickness of the piezoelectric element changes when energized. A power unit mount comprising an actuator, vibration detection means for detecting vibrations of the power unit, and control means for driving the actuator based on a signal from the vibration detection means. 3. A mount for a power unit, comprising a damper means for resiliently supporting a power unit with respect to a vehicle body and damping vibrations of the power unit by the flow of a fluid sealed inside the power unit, wherein the fluid is sealed inside the power unit. a movable member provided in the liquid chamber, an actuator connected to the movable member and made of a stack of piezoelectric elements that is operated in synchronization with the vibration of the power unit and whose plate thickness changes when energized; and the power unit. 1. A mount for a power unit, comprising: vibration detection means for detecting vibrations of the actuator; and control means for driving the actuator based on a signal from the vibration detection means.