JP2913668B2 - Drive device for piezoelectric actuator for vehicle - Google Patents

Description

Description: Object of the Invention [Industrial application field] The present invention relates to a drive device of a piezoelectric actuator for a vehicle that uses a piezoelectric body that expands and contracts according to an applied voltage as a drive source.

[Prior Art] Conventionally, a piezoelectric body such as a piezo element expands and contracts with extremely responsiveness to an applied voltage, and thus is suitable as a drive source of a piezoelectric actuator for a vehicle and has been widely used.

For example, in order to improve the riding comfort when the vehicle is running by switching control of the damping force of the shock absorber, a piezoelectric body is disposed on a piston in the shock absorber, and a passage in a communication passage between the first and second oil chambers. Providing a sliding member that changes the area, expanding the displacement of the piezoelectric body when a high voltage is applied, moving the sliding member, controlling the hydraulic oil flow rate in the communication path, and reducing the damping force of the shock absorber A control technique has been proposed (JP-A-61-85210).

In addition to such a variable damping force type shock absorber for a vehicle, a fuel injection device is used as a drive source for a so-called pilot injection fuel pressurizing piston which injects prior to main fuel injection.

[Problems to be Solved by the Invention] However, the following problems remain unsolved in the conventional driving device for a piezoelectric actuator for a vehicle.

For example, if the impedance of the piezoelectric body, that is, the load side changes, due to adhesion of water droplets or mud to the piezoelectric body, a failure in wiring connection in the piezoelectric body due to vibration of a vehicle, or the like,
The desired expansion and contraction of the piezoelectric body may not be obtained.
Further, when a circuit component in a power supply circuit for applying a high voltage to the piezoelectric body is damaged for some reason, the output voltage value fluctuates, and the desired expansion and contraction of the piezoelectric body cannot be obtained. Sometimes.

In such a situation, in the shock absorber, the switching of the damping force is not performed according to the traveling state of the vehicle and the like, and there is a possibility that the riding comfort and the maneuverability may be deteriorated. There is a possibility that the fuel pressure during the injection will fluctuate.

Alternatively, the withstand voltage of the piezoelectric body or the like must be increased more than necessary because the output voltage from the power supply circuit may exceed the allowable voltage at the time of designing the piezoelectric body and its wiring used. Further, in some cases, there is a possibility that leakage of a high-voltage current or breakage of a piezoelectric body or the like may occur.

The present invention has been made to solve the above problems, and has as its object to prevent various problems caused by abnormal voltage applied to the piezoelectric body.

Configuration of the Invention [Means for Solving the Problems] The means adopted by the present invention in order to achieve the above-mentioned object is, as shown in a block diagram of FIG. A piezoelectric actuator M1 that uses a piezoelectric body MP that expands and contracts, and a booster M2 that boosts an output voltage of a power supply mounted on a vehicle to generate a drive voltage for the piezoelectric actuator M1.
A driving device for a piezoelectric actuator for a vehicle, comprising: an application unit M3 for applying the drive voltage generated by the boosting unit M2 to the piezoelectric body MP. The driving unit is generated by the boosting unit M2 and output to the application unit M3. Abnormality detecting means M4 for detecting an abnormality in voltage; driving voltage output inhibiting means M5 for inhibiting output of the driving voltage boosted by the boosting means M2 when the abnormality detecting means M4 detects a voltage abnormality; In conjunction with the voltage output prohibiting means M5, the piezoelectric body MP
And a charge discharging means M6 for discharging the accumulated charge in the above.

[Operation] The driving device for a piezoelectric actuator for a vehicle having the above-described configuration is configured such that the boosting unit M2 boosts the output voltage of the power supply mounted on the vehicle to generate a driving voltage. The piezoelectric actuator M1 is driven by applying to the MP to expand and contract the piezoelectric body MP.

When driving the piezoelectric actuator M1, the abnormality detecting means M4 is stepped up by the step-up means M2, and when the abnormality detected in the voltage output to the applying means M3 is detected, the driving voltage output prohibiting means M5 operates to increase the step-up voltage. The output of the drive voltage in the means M2 is prohibited, and the charge accumulated in the piezoelectric body MP is discharged by the charge discharging means M6 which operates in conjunction with the drive voltage output prohibiting means M5.

Thus, the driving device for the piezoelectric actuator for vehicle uses the piezoelectric body MP of the piezoelectric actuator M1 to apply an abnormal driving voltage, that is, a driving voltage lower than the proper voltage and a driving voltage higher than the appropriate voltage.
, And an abnormal drive voltage is applied to quickly and forcibly discharge the electric charge accumulated in the piezoelectric body MP.

Prohibiting the output of the drive voltage by the booster M2 may be realized by prohibiting the booster itself of the booster M2.

Next, a driving device for a piezoelectric actuator for a vehicle as one embodiment of the present invention will be described with reference to the drawings. This drive device for a vehicle piezoelectric actuator is used in a damping force control device that adjusts the damping force of a variable damping force type shock absorber having a built-in piezoelectric body.

FIG. 2 is a schematic configuration diagram showing the configuration of the entire damping force control device, FIG. 3 (A) is an overall configuration diagram of the shock absorber partially cut away, and FIG. 3 (B) is a schematic diagram of the shock absorber. It is a principal part expanded sectional view.

As shown in FIG. 2, the vehicle damping force control device 1 of the present embodiment includes a variable damping force type shock absorber (hereinafter simply referred to as a shock absorber) 2FL, 2FR, 2RL, 2RR, and a connection with each of these shock absorbers. And an electronic control unit 4 for controlling the damping force.

As described later, the shock absorbers 2FL, 2FR, 2RL, and 2RR are a piezo load sensor that detects a damping force acting on the shock absorbers 2FL, 2FR, 2RL, and 2RR, and a damping force of the shock absorbers 2FL, 2FR, 2RL, and 2RR. And a piezo actuator for switching between them.

Each of the shock absorbers 2FL, 2FR, 2RL, 2RR has a coil spring 8FL, 8FR, 8RL between the suspension lower arms 6FL, 6FR, 6RL, 6RR of the left and right front and rear wheels 5FL, 5FR, 5RL, 5RR and the vehicle body 7, respectively. , 8RR.

Next, the structure of each of the shock absorbers 2FL, 2FR, 2RL, 2RR will be described. Each of the above shock absorbers 2FL, 2FR,
Since the structures of 2RL and 2RR are all the same, here the left front wheel 5
A description will be given using the shock absorber 2FL on the FL side as an example.
In the following description, the suffixes (F
L, FR, RL, RR) will be omitted as necessary.

As shown in FIG. 3 (A), the shock absorber 2 is fixed to the suspension lower arm 6 via an axle-side member 11a at the lower end on the cylinder 11 side, while the upper end of a rod 13 inserted into the cylinder 11 , Is fixed to the vehicle body 7 together with the coil spring 8 via the bearing 7a and the vibration isolating rubber 7b.

Inside the cylinder 11, an inner cylinder 15, a connecting member 16, a tubular member 17 connected to the lower end of the rod 13, and a main piston 18 slidable along the inner peripheral surface of the cylinder 11 are provided. I have.

A main piston 18 screwed to the cylindrical member 17 by a nut 19 partitions the inside of the cylinder 11 into a first liquid chamber 21 and a second liquid chamber 23, and a hydraulic oil between the two liquid chambers 21 and 23. The flow rate is regulated by the expansion or contraction side fixed orifices 18a, 18b, and the normal damping characteristic of the shock absorber 2 is set to a state of high damping force (hard).

Then, as shown in FIGS. 3A and 3B, a piezo charge sensor 25 and a piezo actuator 27, each of which is an electrostrictive element laminated body in which a thin plate of piezoelectric ceramic is laminated with electrodes interposed therebetween, are built in the inner cylinder 15. , The magnitude of the damping force acting on the shock absorber 2 and the piston 31
To move the plunger 37 and the spool 41 having an H-shaped cross section via the hydraulic oil in the oil-tight chamber 33.

When the spool 41 at the position (origin position) shown in FIG. 3B moves in the direction B in FIG. 3B, the sub flow path 16c connected to the first liquid chamber 21 and the bush 3 connected to the second liquid chamber 23 are moved.
The nine sub flow paths 39b and the flow path 17a in the tubular member 17 are communicated with each other, and the flow rate of the working oil flowing between the first liquid chamber 21 and the second liquid chamber 23 increases. That is, when the piezo actuator 27 expands due to the application of a high voltage, the shock absorber 2 switches its damping characteristic from a large damping force (hard) state to a small damping force (soft) side. Is returned to the state of large damping force (hard).

Note that a hydraulic oil supply path 38 is provided between the oil-tight chamber 33 and the first liquid chamber 21 together with a check valve 38a so as to keep the amount of hydraulic oil in the oil-tight chamber 33 constant.

Further, an oil passage 41d is provided on the partition wall 41a of the spool 41,
A lower communication hole 41e having a diameter larger than the diameter of the oil passage 41d is formed in the annular groove 40 of the 41.

The shock absorber 2 is provided with a slidable plate valve 45 in an end space 39c following the sub flow path 39b. The sliding speed of the main piston 18 in the cylinder 11 is controlled by an oil hole 45a formed in the plate valve 45. And large diameter oil hole 45b
And is adjusted according to the flow direction of the hydraulic oil passing through.

Next, an electronic control unit 4 for switching and controlling the damping force of the shock absorber 2 will be described with reference to FIG.

The electronic control unit 4 includes a steering sensor 50 for detecting a steering angle of a steering wheel (not shown), a vehicle speed sensor 51 for detecting a running speed of the vehicle, and a rotation of an engine as sensors for detecting a running state of the vehicle. A neutral switch 52 for detecting a neutral position of a transmission (not shown) that outputs after shifting, and a stop lamp switch that emits a signal when a brake pedal (not shown) is depressed.
The detection signal of each sensor and switch is input to the electronic control unit 4.

The electronic control unit 4 that outputs a control signal to the piezo actuator 27 based on these detection signals, the detection signal of the piezo load sensor 25 of each shock absorber 2, and the like,
U4a, ROM4b, and RAM4c are mainly configured as a logic operation circuit, and input / output with the outside is performed by an input unit 4e and an output unit 4f which are interconnected with these via a common bus 4d.

The electronic control unit 4 further includes a damping force detection circuit 55 connected to the piezo load sensor 25, a steering sensor 50,
A waveform shaping circuit 56 connected to a vehicle speed sensor 51, a neutral switch 52, and a stop lamp switch 53, an output circuit 58 that outputs a lighting current to a lamp 57 for abnormality notification, and a high voltage power supply circuit 60 connected to a battery (not shown). , A high voltage application circuit 61 connected to the piezo actuator 27, a rapid discharge circuit 62 connected to the high voltage power supply circuit 60 on the secondary side, and the like. Then, the damping force detection circuit 55 and the waveform shaping circuit 5
6, the A / D converter 59 is connected to the input section 4e, the output circuit 58, the high voltage power supply control circuit 60a of the high voltage power supply circuit 60, the high voltage application circuit 61, and the rapid discharge control circuit 62a of the rapid discharge circuit 62 are connected to the output section. 4f respectively. The A / D converter 59 includes a resistor 60b for detecting the current of the high-voltage power supply circuit 60,
0 secondary-side wiring and primary-side wiring are connected. Therefore, the CPU 4a calculates the battery voltage V8, the primary current i1 and the secondary voltages V500, V500 in the transformer 60c of the high-voltage power supply circuit 60.
-100 is read through an A / D converter 59, and a control signal is output to an output circuit 58 that supplies a current for lighting to a lamp 57 for abnormality notification to control the lighting of the lamp 57.

The damping force detection circuit 55 is composed of each piezo load sensor 25FL, 25FR, 25
RL and 25RR are provided corresponding to each other, and each of the detection circuits reduces the current flowing through the piezo load sensor 25 according to the acting force applied to the shock absorber 2 from the road surface by the damping of the shock absorber 2. It is configured to convert into a force and a damping force change rate and output to the CPU 4a.
Accordingly, the CPU 4a performs a waveform shaping circuit 56 for shaping the detection signal of the damping force detection circuit 55 and the detection signal of the steering sensor 50 and the like into a signal suitable for processing in the CPU 4a, and outputs the signal. And outputs a control signal to the corresponding high voltage application circuit 61 in order to switch the damping characteristic of the shock absorber 2 according to the result.

The high-voltage power supply circuit 60 periodically cuts off a current flowing through a primary coil of the transformer 60c based on an output signal from an oscillator (not shown) to generate a high voltage in a secondary coil of the transformer 60c. A periodic on / off control of a field effect transistor (hereinafter referred to as FET) 60d connected in series between the primary coil of the transformer 60c and the resistor 60b, and an on / off control based on a control signal from the CPU 4a. High-voltage power supply control circuit 60a for executing off control, diodes 60e and 60f for half-wave rectifying the secondary current, and capacitors 60g and 60h connected in parallel with the secondary coil and for smoothing and storing the electric charge
And so on. Therefore, the CPU 4a outputs a control signal to the high-voltage power supply control circuit 60a to
And whether or not boosting is possible. The intermediate tap of the secondary coil is grounded.

The high-voltage application circuit 61, which receives a high voltage from the high-voltage power supply circuit 60, changes the driving voltage for the piezo actuator output from the high-voltage power supply circuit 60 according to a control signal (a damping force switching signal) from the CPU 4a. The piezo actuator 27 is applied to drive the piezo actuator 27 to switch the damping force of the shock absorber 2 according to the damping force switching signal. More specifically, when a low-level signal is input as a damping force switching signal from the CPU 4a, the piezo actuator is applied by applying a high voltage V500.
When a high-level signal is input as a damping force switching signal, the voltage is switched to a negative voltage V-100 and applied to contract the piezo actuator 27. It should be noted that a diode is connected between each high voltage application circuit 61 and the piezo actuator 27 as shown in the figure.

Therefore, the damping force characteristic of each shock absorber 2 is such that when the piezo actuator 27 is extended by applying a high voltage, the first liquid chamber 21 in the shock absorber 2 is provided by the spool 40 (FIG. 3) described above. When the flow rate of the hydraulic oil flowing between the hydraulic fluid and the second liquid chamber 23 increases, the damping force becomes small (soft), and when the electric charge is discharged by the negative voltage and the piezo actuator 27 contracts, the hydraulic oil flow rate increases. Since it decreases, the damping force becomes large (hard).

Rapid discharge circuit connected to the secondary side of high voltage power supply circuit 60
62 is configured to rapidly and forcibly discharge the electric charge stored in each piezo actuator 27. An FET 62b and a resistor 62 are connected in parallel between both outputs of the secondary coil of the transformer 60c. 62c, and a rapid discharge control circuit 62a that performs on / off control of the FET 62b based on a control signal from the CPU 4a. Therefore, the CPU 4a outputs a control signal to the rapid discharge control circuit 62a to turn on the FET 62b, short-circuit the secondary side of the transformer 60c, and transfer the electric charge stored in each piezo actuator 27 to the resistor 62c.
Can be discharged quickly and forcibly.

Next, the damping force control performed by the vehicle damping force control device 1 of the present embodiment having the above-described configuration will be described with reference to the flowchart of FIG.

FIG. 5 shows a damping force control routine that is repeatedly executed by the electronic control unit 4 from when an ignition switch (not shown) is turned on until it is turned off.

As shown in FIG. 5, in the damping force switching routine,
Initial processing performed only when the ignition switch is turned on, that is, clearing the internal register of the CPU 4a,
The flags FING and FHVNG set in the processing described later are reset.

Thereafter, it is first determined whether or not the boosting in the high-voltage power supply circuit 60 is completed and is in a state sufficient to drive the piezo actuator 27 based on the elapsed time after the ignition switch is turned on (step 110). Wait for completion.

If it is determined that the boosting has been completed, step 250
And the high voltage abnormality flag FHVN whose value is set to 1 in step 200.
The set state of G is sequentially determined (steps 120 and 130).

In the first processing after the ignition switch is turned on, since both of the flags are reset to the value 0, it is determined that there is no abnormality in the power supply system and the battery voltage V
B, both output voltages V500 and V-100 of the high-voltage power supply circuit 60 are read via the A / D converter 59 (step 140). Thereafter, it is sequentially determined whether or not the battery voltage VB and the output voltages V500 and V-100 are within appropriate ranges defined by the following equations (1) to (3) (steps 150, 160 and 170).

VB ≧ VBL (1) V500L ≦ V500 ≦ V500H (2) V−100L ≦ V−100 ≦ V−100H (3) In the above equations, VBL is a lower limit judgment value of the battery voltage. , V500L and V500H are abnormality judgment values set as upper and lower limits of the normal value when the output voltage of the high-voltage power supply circuit 60 is 500 V, and V-100L and V-100H indicate that the output voltage is -10.
This is the abnormality determination value set as the upper and lower limit of the normal value when it is 0v.

If all of the equations corresponding to the steps are satisfied in the above steps 150, 160, 170, the drive voltage generation side (high-voltage power supply) is applied when applying the drive voltage to the piezo actuator 27 in addition to the determination in steps 120, 130. Circuit 6
Since it can be determined that there is no abnormality on the load side (0) and on the load side (piezo actuator 27), this process is terminated once after the damping force of the shock absorber 2 is switched (step 180).

It should be noted that the damping force switching processing in step 180 is well-known, and therefore only an outline of the processing will be described.

That is, based on the detection signals from the steering sensor 50, the vehicle speed sensor 51, etc., the traveling state (the steering angle θ, the vehicle speed S, etc.)
The road surface state is determined based on the detection signal from the damping force detection circuit 55, and a low-level or high-level control signal is output to the high-voltage application circuit 61 in accordance with the result to expand and contract the piezo actuator 27, and Switch the softening or hardening damping force.

While performing such normal damping force switching,
If it is determined in any of steps 160 and 170 that the output voltage is not within the appropriate range, the determination is made in steps 120, 130 and 150 that there is no abnormality in the power supply system, and the drive voltage generation side (high-voltage power supply circuit 60) ) Or that an abnormality has occurred on the load side (piezo actuator 27), prohibits boosting in the high-voltage power supply circuit 60, starts rapid discharge by the rapid discharge circuit 62, and further starts the high-voltage application circuit 61 The application of a high voltage to the piezo actuator 27 is prohibited (step 190). That is, the high-voltage power supply control circuit 60a is connected to the FET 60d so as to prevent the boosting from being continued while the drive voltage generation side or the load side is abnormal.
Is turned off to stop boosting in the high-voltage power supply circuit 60, and the rapid discharge control circuit 62a controls the FET 62b so that the charge stored in the piezo actuator 27 is forcibly discharged by the high voltage applied up to that time. In the ON state, rapid discharge in the rapid discharge circuit 62 via the resistor 62c is started.

As a result, when step 190 is executed, the piezo actuator 27 contracts, the spool 41 returns to the home position shown in FIG. 3B, and the damping force of the shock absorber 2 is fixed by hardware.

After execution of step 190, the piezo actuator 2
7 that the high voltage applied to 7 is abnormal
High voltage abnormality flag F indicating that boosting is prohibited in
HVNG is set to the value 1 (step 200), and then the CPU 4a
Then, a lighting command signal is output to the output circuit 58, and a current for lighting is supplied from the output circuit 58 to the lamp 57, the lamp 57 for abnormality notification is turned on (step 210), and the process is temporarily terminated.

Once the value 1 is set in the high-voltage abnormality flag FHVNG in this way, it is determined in step 130 that FHVNG = 0 is not satisfied, and then the primary current i1 of the transformer 60c is determined.
Is read via the A / D converter 59 (step 220), and it is determined whether or not the current i1 is within an appropriate range defined by the following equation (4) (step 230).

i1 ≦ i0 (4) where i0 is an overcurrent determination value of the primary current of the transformer 60c.

If it is determined in step 230 that the expression (4) is not satisfied and it is determined that the primary side current is excessive, the primary side current is prohibited in step 190 despite the prohibition of boosting in the high voltage power supply circuit 60. Since the current i1 is excessive, it is determined that the high-voltage power supply circuit 60 has a step-up abnormality such that the operation cannot be stopped, and the step-up / high-voltage output contrary to the step-up prohibition and the strong discharge occur. Is not performed at the same time, the boosting prohibition in the high-voltage power supply circuit 60 made in step 190 is canceled to return to the state before the boosting is prohibited,
The rapid discharge via the resistor 62c of the rapid discharge circuit 62 started in step 190 is prohibited by turning off the FET 62b. Further, in order to prevent the piezo actuator 27 from being driven by the application of the abnormal voltage, the application of the high voltage by the high voltage application circuit 61 is continuously prohibited (step 240).

As a result, when step 240 is executed, the damping force of the shock absorber 2 is fixed by hardware similarly to step 190 described above.

After the execution of step 240, a value 1 is set to a step-up prohibition abnormality flag FING indicating that the primary current i1 of the transformer 60c is excessive despite the step-up being prohibited (step 2).
50) Then, the process proceeds to step 210, where the abnormality notification lamp 57 is turned on, and the process is temporarily terminated.

On the other hand, in step 230, the primary side current i1 becomes the overcurrent determination value i0.
Even if it is determined that the voltage is below, since it is determined in step 130 that there is an abnormality in the voltage system applied to the piezo actuator 27, it can be determined that there is still some abnormality, and the process proceeds to step 190 and subsequent steps. As described above, the boosting prohibition and the like are executed.

If it is determined in step 150 that the battery voltage VB is lower than the lower limit determination value VBL, the output voltages V500 and V-100 of the high-voltage power supply circuit 60 are expressed by the following equations (5) and (100), respectively. It is sequentially determined whether or not 6) is satisfied (steps 260 and 270).

V500 ≦ V500H (5) V−100L ≦ V−100 (6) When both of the above equations are satisfied in the corresponding steps 260 and 270, the determination is made in step 150 that the battery voltage is insufficient. Since it can be determined that the output voltage of the high voltage power supply circuit 60 is not in a state sufficient to drive the piezo actuator 27, the application of the high voltage to the piezo actuator 27 by the high voltage application circuit 61 is prohibited (step 280). The process ends.

On the other hand, in either of steps 260 and 270, the high-voltage power supply circuit 6
When it is determined that the output voltage of 0 is higher than the upper limit value or lower than the lower limit value of the appropriate range, along with the determination of the battery voltage drop in step 150, some abnormality is still present on the drive voltage generation side or the load side. Is determined to have occurred, and the process proceeds to the above-described step 190 and subsequent steps to execute step-up prohibition in the high-voltage power supply circuit 60 and the like.

As described above, the drive device for the vehicle piezoelectric actuator of the present embodiment, that is, the damping force control device performs a damping force switching process of applying a high voltage to the piezo actuator 27 and switching the damping characteristics of the shock absorber 2. It is always determined whether or not the output voltage from the high-voltage power supply circuit 60 is within an appropriate range. If it is determined that the output voltage is abnormal, the high-voltage generation side (high-voltage power supply circuit 60) or the load side (Piezoactuator 27) assuming that some abnormality has occurred, prohibits boosting in high-voltage power supply circuit 60, starts rapid discharge by rapid discharge circuit 62, and applies high voltage to piezoactuator 27 by high-voltage application circuit 61. Is banned.

As a result, it is possible to reliably prevent the piezoelectric actuator 27 from being damaged due to the application of an excessively high voltage, and to prevent the heat generation and damage of the high-voltage power supply circuit 60 from being excessively boosted. 27 stretches can be avoided. Therefore, the piezo actuator 27
In the shock absorber 2 that switches its damping force by using the drive source, even if an abnormality occurs in the output voltage due to a breakage of a circuit element or the like, the damping force is not switched based on such an abnormality. There is no deterioration in ride comfort. Also, since excessive boosting is avoided, dielectric breakdown can be prevented without unnecessarily increasing the withstand voltage of the wiring and the like, and the reliability of avoiding leakage of high-voltage current can be increased.

Further, when the battery voltage drops, it is not determined whether or not the output voltage is within an appropriate range. Therefore, it is possible to erroneously detect a drop in the output voltage due to insufficient boosting of the battery voltage, and eventually the high-voltage power supply circuit 60, as an abnormality. In addition, it is possible to prevent an insufficient voltage from being applied to the piezo actuator 27. Thereby, the reliability of the switching of the damping force of the shock absorber 2 can be improved.

If the primary current i1 is excessive despite the prohibition of boosting in the high-voltage power supply circuit 60, the prohibition of boosting is canceled and the high-voltage power supply circuit 60 is brought into a state before the boosting is prohibited. At the same time, the rapid discharge by the rapid discharge circuit 62 is prohibited, so that the boosting / high voltage output contrary to the prohibition of boosting and the forced discharge are not performed at the same time, and the high voltage power supply circuit 60 and the rapid discharge circuit 62 are protected. can do.

Although an embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention. .

For example, in the present embodiment, the presence / absence of the primary side current abnormality of the transformer 60c is determined in parallel with the presence / absence of the output voltage abnormality. However, the primary side current abnormality determination is omitted, or the primary side current abnormality is determined. An abnormality in the output voltage from the high-voltage power supply circuit 60 can be determined only by the determination.

Further, once it is determined that an output voltage abnormality has occurred, the switching of the damping force is not performed until the ignition switch is turned off, and a flag indicating the voltage abnormality when the ignition switch is turned on again. And the damping force can be switched. However, even after the occurrence of the output voltage abnormality is determined, the state of the output voltage is continuously monitored, and the predetermined conditions such as the spontaneous disappearance of the voltage abnormality and the lapse of a predetermined time are determined. When the condition is satisfied, the damping force can be switched, or the upper and lower limits of the appropriate range of the output voltage and the like can be changed to change the abnormality determination condition itself according to the frequency of occurrence of the abnormality.

Further, it is needless to say that the present invention can be applied to not only a shock absorber of a vehicle but also a driving device of various actuators for a vehicle such as an actuator for pilot injection.

Effect of the Invention As described in detail above, the driving apparatus for a piezoelectric actuator for a vehicle according to the present invention, when a high voltage is applied to the piezoelectric body of the piezoelectric actuator for a vehicle to drive the piezoelectric actuator, abnormality is found in the driving voltage. If so, it is determined that some abnormality has occurred on the drive voltage generation side or the load side, the output of the drive voltage is prohibited, and the charge stored in the piezoelectric body is rapidly and forcibly discharged.

As a result, according to the drive device for a piezoelectric actuator for a vehicle of the present invention, it is possible to prevent damage to the piezoelectric actuator and the drive voltage generation source and inadvertent expansion and contraction of the piezoelectric body due to abnormal drive voltage. Also, since the excessively boosted high voltage current does not flow through the wiring and the like, the dielectric breakdown can be prevented without increasing the withstand voltage of the wiring and the like more than necessary, and the reliability of avoiding the leakage of the high voltage current is improved. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of the present invention, and FIG. 2 is a schematic configuration diagram showing an entire configuration of a damping force control device when one embodiment of the present invention is used in a damping force control device. 3 (A) is a partial cross-sectional view showing the structure of the shock absorber of the damping force control device, FIG. 3 (B) is an enlarged cross-sectional view of a main part of the shock absorber, and FIG. 4 is an electronic control device of the present embodiment. FIG. 5 is a flowchart showing a damping force switching routine. 2FL, 2FR, 2RL, 2RR ... Variable damping force type shock absorber 4 ... Electronic control unit 25FL, 25FR, 25RL, 25RR ... Piezo load sensor 27FL, 27FR, 27RL, 27RR ... Piezo actuator 60 ... High voltage power supply Circuit, 60c Transformer 61 High voltage application circuit, 62 Rapid discharge circuit

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Fukami 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Yutaka Suzuki 1-1-1, Showa-cho, Kariya-shi, Aichi Nihon Denso Co., Ltd. (72) Inventor Yuji Yokoya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yasuhiro Tsutsumi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP JP-A-61-85210 (JP, A) JP-A-64-21237 (JP, A) JP-A-63-133450 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16F 9 / 00-9/58 B60G 17/015 H02N 2/00

Claims (1)

(57) [Claims] 1. A piezoelectric actuator using a piezoelectric body that expands and contracts according to an applied voltage, a booster that boosts an output voltage of a power supply mounted on a vehicle to generate a drive voltage for the piezoelectric actuator, and a booster. A driving device for a piezoelectric actuator for a vehicle, comprising: an applying unit that applies the generated driving voltage to the piezoelectric body; and an abnormality detecting unit that detects an abnormality of a voltage generated by the boosting unit and output to the applying unit. A driving voltage output prohibiting unit that prohibits the output of the driving voltage boosted by the boosting unit when the abnormality detecting unit detects a voltage abnormality; A driving device for a piezoelectric actuator for a vehicle, comprising: a charge discharging unit configured to discharge a charge.