JPH01114522A - Engine mounting device - Google Patents

Abstract

PURPOSE:To permit the proper vibration damping corresponding to the revolution speed by increasing the electric charge and discharge speed according to the increase of the engine revolution speed, in a vibration damping device which performs electric charge and discharge for an electric strain element in an engine mount part, synchronized with an engine crankshaft. CONSTITUTION:An electric strain element such as plate-shaped piezoelectric element is inserted in horizontal layered form between the rubber elastic members in an engine mount part, and electric charge and discharge are executed by an electric charge controlling transistor 54 and an electric discharge controlling transistor 56, and the damping of the engine vibration is performed. The control of the electric charge and discharge is carried out through the ON/OFF duty ratio control of each amplification control circuit 58, 60 by a microcomputer 62 on the basis of the detection values of a crank position sensor 68 and a crank angle sensor 70, and when the engine revolution speed increases, control is performed so that the electric charge and discharge speed is increased. Therefore, the extension quantity of the electric strain element is prevented from being short of in high speed revolution and prevented from being excessive in low speed revolution, and the proper vibration damping effect can be always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an engine mounting device for vibration-proofly supporting an engine (internal combustion engine) from a vehicle body, and particularly to an engine mounting device including an electrostrictive element such as a piezo element.

BACKGROUND ART In vehicles such as automobiles, an electrostrictive element such as a piezo element is included as one of the engine mounting devices for supporting the engine from the vehicle body in a vibration-proof manner. Engine mounting devices configured to damp vibrations transmitted from the engine to the vehicle body have already been proposed, and are disclosed in, for example, JP-A-59-23139, JP-A-59-23140, and JP-A-59-65640.
No. 60-86645.

Problems to be Solved by the Invention Electrostrictive elements such as piezo elements generally elongate in proportion to an increase in the amount of electric charge stored therein, that is, an increase in the amount of charge.
It exhibits an electro-strain characteristic in which the amount of elongation decreases in accordance with the decrease in the amount of charge due to discharge, and therefore, the charging and discharging of the electrostrictive element is simply controlled in synchronization with the crank angle of the engine. The amount of elongation of the electrostrictive element fluctuates as the engine speed changes, and the amount of elongation of the electrostrictive element is insufficient at high speed rotations where the rate of change of crank angle becomes faster.On the other hand, at low speed rotations where the crank angular speed is slow, the amount of elongation of the electrostrictive element is insufficient. The amount of elongation of the electrostrictive element becomes excessive. As a result, the vibration damping characteristics change as the engine speed changes, the amount of muffled sound reduction decreases at high speeds, and the electrostrictive element becomes a new source of vibration at low speeds, causing the vibration damping characteristics to significantly deteriorate. It starts to get worse.

In view of the above-mentioned problems, the present invention aims to provide an improved engine mounting device that can give an electrostrictive element a predetermined amount of elongation in synchronization with the crank angle regardless of changes in engine speed. The purpose is

Means for Solving the Problems According to the present invention, in an engine mounting device including an electrostrictive element, a charge/discharge switching means for charging and discharging the electrostrictive element, and a crankshaft of the engine are provided. Achieved by an engine mounting device having charge/discharge control means for switching and controlling charging and discharging of the electrostrictive element by the charge/discharge switching means in synchronization with the angle of rotation, and increasing the charging/discharging speed in accordance with an increase in engine rotation speed. be done.

The charging/discharging control means may be configured to control discharging and charging of the electrostrictive element in synchronization with the timing of the primary explosion of the engine.

The charge/discharge control means may be configured to start discharging the electrostrictive element when the piston of each cylinder is located at a top dead center position or a bottom dead center position.

Effects and Effects of the Invention According to the above-described configuration, the charging and discharging speed of the electrostrictive element increases as the engine speed increases, so that
The amount of elongation of the electrostrictive element does not become insufficient during high-speed rotation.
In addition, the amount of expansion of the electrostrictive element does not become excessive during low speed rotation, and as a result, the amount of expansion of the electrostrictive element remains approximately constant regardless of the engine rotation speed. The required vibration damping characteristics can now be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 shows the general arrangement of the engine mounting arrangement. In FIG. 1, reference numeral 10 indicates an engine, and reference numeral 12 indicates a transaxle connected to the engine 10. These are arranged along the width direction of the vehicle, that is, placed horizontally, and their rolling inertia main axis Vibration-proof support is provided from the vehicle body by four mounts: a front mount 14 and a rear mount 16 located on both sides of the rolling inertia main axis, and a right mount 18 and a left mount 20 located on an extension of or near the rolling inertia main axis. .

The engine mounting device according to the present invention is applied to mounts where the load shared by the engine 10 and the transaxle 12 is large, and in the embodiment shown in FIG. 1, the right mount 18 and the left mount 20.

2 to 4 each show a vibration isolating rubber device including an electrostrictive element. In FIGS. 2 to 4, reference numerals 30 and 32 denote mounting fittings, 34 a rubber-like elastic member provided to connect the fittings 30 and 32, and 36 a plate-shaped piezo element. A laminated body of electrostrictive elements 38 as shown in FIG. The electrostrictive element stack 36 is configured to expand in the stacking direction of the electrostrictive elements 38 by applying a voltage to the electrostrictive elements 38, and the direction of expansion is approximately coincident with the reciprocating direction of the piston of the engine 10. It is preferable that the

FIGS. 5 and 6 show other examples of vibration-proof Bohm devices made of electrostrictive material suitable for use in the engine mounting device according to the present invention. In addition, in Figures 5 and 6,
Portions corresponding to FIGS. 2 to 4 are designated by the same reference numerals as those shown in FIGS. 2 to 4. The electrostrictive element laminate 36 is located between the two mounting brackets 30 and 32 and is fixedly connected to one of the mounting brackets 32, and is provided extending between the two mounting brackets 30 and 32 so as to connect the two mounting brackets 30 and 32. are embedded in a rubber-like elastic member 34 that connects the two to each other.

The surface 40 of the electrostrictive element laminate 36 facing the mounting bracket 30 is
The rubber-like elastic member 34 is in close contact with the opposing surface 42 of the electrostrictive element laminate 36, but is not bonded to it and can be peeled off from the other. A hole 42 for guiding air is provided between the contact surface 40 of the rubber-like elastic member 34 and the rubber-like elastic member 34 .

As a result, when the mounting brackets 30 and 32 are largely displaced in the direction away from each other, the rubber-like elastic member 3
4 is tensed, but the opposing surface 40 of the electrostrictive element laminate 36 and the opposing surface 42 of the rubber-like elastic member 34 are separated from each other, which causes an excessive tensile force to act on the electrostrictive element laminate 36. is avoided.

It will be done.

FIG. 7 shows a control system in an engine mounting device according to the present invention. The control system includes a control unit 50, which includes a charge control transistor 54 that selectively connects the electrostrictive element stack 36 to a battery power source 52, and a charge control transistor 54 that selectively connects the electrostrictive element stack 36 to ground. A discharge control transistor 56 to be connected,
An amplification control circuit 58 that turns on and off the charge control transistor 54, an amplification control circuit 60 that turns on and off the discharge control transistor 56, and two amplification control circuits 58.
and 60, and two waveform shaping circuits 64 and 66. The waveform shaping circuit 64 is given a signal indicating the crank angle from the crank position sensor 68, and another waveform shaping circuit 66
A signal indicating the crank angle is input from a crank angle sensor 70 to the crank angle sensor 70.

When the charging control transistor 54 is in the on state, a voltage is applied to the electrostrictive element stack 36 by the battery power supply 52, that is, charging is performed, whereas when the discharge controlling transistor 56 is in the on state, the electrostrictive element Laminated body 3
6 of the charge is discharged, that is, a discharge occurs.

The microcomputer 62 has a crank position sensor 68
Information regarding the crank position and crank angle sensor 7
Based on the information regarding the crank angle from 0, in a four-cylinder engine, as shown in FIG. The strain element stack 36 is repeatedly charged and discharged every 90 degrees of the crank angle,
Further, the charging/discharging timing is set so that charging starts when the piston of each cylinder is located at the top dead center position or the bottom dead center position.

As a result, the electrostrictive element stack 36 is repeatedly charged and discharged in synchronization with the timing of the primary explosion of the engine.

The microcomputer 62 finds the rate of change in the crank angle, that is, the engine speed, from the information regarding the crank angle from the crank angle sensor 70, and when the engine speed is high, the charging speed and the discharging speed are increased. .

As a result, the charging and discharging characteristics of the electrostrictive element stack 36 during low speed rotation become as shown in FIG. 8(A), and during high speed rotation as shown in FIG. 8(B). become.

As described above, the charging and discharging speed of the electrostrictive element stack 36 is increased as the engine speed increases, so that the charge accumulated in the electrostrictive element stack 36 becomes almost constant regardless of changes in the engine speed. Accordingly, the amount of elongation of the electrostrictive element laminate 36 also becomes substantially constant regardless of changes in engine speed, so that the required vibration damping characteristics can always be obtained regardless of changes in engine speed.

The charging and discharging speed of the electrostrictive element stack 36 is controlled by the transistor 5.
This may be done by controlling the on-off duty ratio of 4 and 56, and as shown in FIG. 9, this duty ratio may be increased as the engine speed increases.

Further, the charge/discharge control of the electrostrictive element stack 36 as described above is prohibited when the starter signal is on, that is, when the starter is activated, as shown in FIG. 10, considering the charge/discharge balance of the battery power source 52. As a result, charging of the electrostrictive element stack 36 may be stopped, thereby providing sufficient power to the starter and improving engine startability.

In addition, when the voltage of the battery power source 52 is below a predetermined value, the eleventh
As shown in the figure, an electrostrictive element stack 36 as described above
The charge/discharge control may be stopped and charging of the electrostrictive element stack 36 may be prohibited.

In addition, using two crank angle sensors, the microcomputer 62 determines whether or not there is a contradiction between the crank angles detected by both sensors. When a contradiction occurs, it is determined that an abnormality has occurred in the sensor and the In order to avoid the problem of charging and discharging being performed, as shown in FIG. 12, at this time, the charging and discharging control of the electrostrictive element stack 36 is stopped and charging of the electrostrictive element stack 36 is prohibited. It's okay to be.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto, and it is understood that various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the general arrangement of an engine mounting device, FIGS. 2 to 4 are longitudinal cross-sectional views each showing a vibration isolating rubber device including an electrostrictive element, and FIG. 5 is an engine according to the present invention. A vertical cross-sectional view of a vibration-proof rubber device with an electrostrictive element suitable for use in a mounting device, FIG. 6 is a line V in FIG.
7 is a block diagram showing an example of the control system of the engine mounting device according to the present invention, and FIG. 8 (A) and (B) are the charging and discharging characteristics of the electrostrictive element stack. FIG. 9 is a graph showing duty ratio characteristics for charge/discharge speed control, and FIGS. 10 to 12 are time charts showing examples of ancillary control suitable for being incorporated into the engine mounting device according to the present invention. . 10...Engine, 12...Transaxle, 1
4...Front mount, 16...Rear mount, 1
8...Right mount, 20...Left mount,
30.32... Mounting bracket, 34... Rubber-like elastic member, 36... Electrostrictive element laminate, 38... Electrostrictive element, 4
0... Opposing surface. 42... Contact surface, 44... Hole, 50... Control unit. 52...Battery power supply, 54...Charging control transistor, 56...Discharging control transistor, 58.6
0...Amplification control circuit, 62...Microcomputer. 64.66...Waveform shaping circuit, 68...Crank position sensor, 70...Crank angle sensor Patent applicant: Toyota Motor Corporation representative
Patent Attorney Masaki AkashiFigure 5, Figure 6, Figure 8 (B) No. 1 cylinder ,,A, corner
Top dead center Figure 9 Engine rotating machine → Figure 10 Crank angle → Figure 11 Crank angle → Figure 12 Crank angle →

Claims (3)

[Claims] (1) In an engine mounting device including an electrostrictive element, a charging/discharging switching means for charging and discharging the electrostrictive element, and a charging/discharging switching means for charging the electrostrictive element in synchronization with a crank angle of the engine. and charging/discharging control means that switches and controls discharge and increases the charging/discharging speed according to an increase in engine rotational speed. (2) In the engine mounting device according to claim 1, the charging/discharging control means is configured to control charging and discharging of the electrostrictive element in synchronization with the timing of the primary explosion of the engine. An engine mounting device characterized by: (3) In the engine mounting device according to claim 1 or 2, the charge/discharge control means controls the electrostrictive element when the piston of each cylinder is located at the top dead center position or the bottom dead center position. An engine mounting device configured to initiate a discharge of.