JPH039135A - Driving gear of or piezoelectric actuator for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a drive device for a piezoelectric actuator for a vehicle that uses a piezoelectric material that expands and contracts in response to an applied voltage as a drive source.

[Prior Art] Piezoelectric bodies such as piezo elements have been widely used and are suitable as drive sources for piezoelectric actuators for vehicles because they expand and contract with extremely high responsiveness to applied voltage.

For example (Dai), in order to improve the riding comfort of a vehicle by switching and controlling the damping force of a shock absorber, a piezoelectric body is disposed on the piston in the shock absorber, and the communication passage between the first and second oil chambers is A sliding member is provided to change the area of the passage, and the extraction member is moved by an amount that increases the displacement of the piezoelectric body when high voltage is applied to control the flow rate of hydraulic oil in the communication passage, thereby controlling the damping force of the shock absorber. A technique has been proposed (Japanese Unexamined Patent Publication No. 85210/1983).

In addition, it is used not only in variable damping force shock absorbers for vehicles, but also in fuel injection devices (as a driving source for a fuel pressurizing piston for so-called pilot injection, which injects fuel prior to main fuel injection).

Then, the driving device of the piezoelectric actuator for a vehicle applies a voltage of several hundred volts to the piezoelectric body over a period of time required depending on the detected road surface condition, etc., and stretches the piezoelectric body during that period. , change the damping force of the shock absorber from hard to soft, reverse 1:
The damping force is hard restored by applying a negative voltage for a short period of time to discharge the accumulated charges in the piezoelectric body and contract the piezoelectric body. In this way, the vehicle piezoelectric actuator drive device controls the shock absorber round fuel injection system, such as damping force switching and pilot injection, while the vehicle is running.

The quality of the expansion and contraction behavior of the piezoelectric body directly affects the reliability of shock absorber damping force switching, pilot injection, etc. when the vehicle is running. For this reason, drive tests of the piezoelectric body are essential, and drive tests are periodically conducted in a test mode in which a high voltage is applied to the piezoelectric body to experimentally expand and contract it.
Or it is carried out irregularly.

This drive test tests whether the piezoelectric body can properly expand and contract. Execute the extension test mode to test whether the damping force of the shock absorber can actually be quickly switched from hard to soft. We are testing whether the damping force quickly returns to its hard state.

[Problems to be Solved by the Invention] However, the following problems remain unsolved in conventional piezoelectric actuator drive devices for vehicles.

If the vehicle starts running after the above-mentioned shock absorber extension test is completed, judging from the road surface condition, the damping force of the shock absorber should automatically switch to the hard state. The actual damping force remained in the soft state, or when the contraction test mode remained, the damping force remained in the hard state even though it should have switched to the soft state. As a result, the damping force does not match the road surface condition. As a result, ride comfort may deteriorate.

Additionally, care is normally taken to prevent high voltage from being applied to the piezoelectric body when the vehicle is stopped; however, in the drive test mode described above, high voltage was applied even when the vehicle was stopped. Occurrence of such malfunctions, which may cause electrical leakage or, in some cases, inconveniently expose maintenance workers to electrical stimulation. (This occurs regardless of the results of other tests.)

SUMMARY OF THE INVENTION The present invention was made to solve the above-mentioned problems, and it is an object of the present invention to avoid problems associated with conducting drive tests of piezoelectric plates.

[Means for Solving the Problem] The means adopted by the present invention to achieve the above object (as shown in the block diagram of FIG. 1 illustrating its basic configuration), a piezoelectric actuator M1 using a piezoelectric body MP that expands and contracts depending on the applied voltage; and a booster M2 that boosts the output voltage of a power source mounted on the vehicle to generate a driving voltage for the piezoelectric actuator M1.
and a vehicle piezoelectric actuator drive device having a running application means M3 that applies the drive voltage generated by the boosting means M2 to the piezoelectric body MP at a desired timing, when an external operation is performed. Piezoelectric actuator M1
mode setting means M for setting the drive mode of
4, r81 in which the test mode is set by the mode setting means M4; test mode applying means M5 for applying the driving voltage of the boosting means M2 to the piezoelectric body MP; and 1 after the test mode is set by the setting means M4. :.

The gist thereof is that the test mode canceling means M6 is provided to cancel the setting of the test mode when a predetermined condition regarding time or running state is satisfied.

[Function] Method for driving a piezoelectric actuator for a vehicle having the above configuration When the vehicle is running, the boosting means M2 boosts the output voltage of the power source mounted on the vehicle to generate a drive voltage, and the driving voltage is applied to the driving voltage by the driving voltage applying means M3. By applying the voltage to the piezoelectric body MP of the piezoelectric actuator M1 at a desired timing, the piezoelectric body MP is expanded and contracted to drive the piezoelectric actuator M1.

On the other hand, when an external operation is performed and the mode setting means M4 sets the test mode, the test mode application means M5 operates while the test mode is set, and applies the driving voltage of the boosting means M2 to the piezoelectric body MP of the piezoelectric actuator M1. is applied to the piezoelectric actuator M by expanding and contracting the piezoelectric body MP in the test mode.
1 is driven.

After the test mode is set 1: When a predetermined condition regarding the time or the running state of the vehicle is satisfied, the test mode canceling means M6 operates to cancel the test mode setting, and until then, the test mode applying means M5 The application of the drive voltage to the piezoelectric body MP that was being executed is stopped.

As a result, when the vehicle is running after the application of the test mode application means M5 is stopped, only the application of the drive voltage by the application means M3 during running is performed.The piezoelectric actuator M1 is automatically driven according to the driving state. In addition, the state of voltage application to the piezoelectric body MP when the vehicle is stopped after the application is stopped (
This will return to the state when the vehicle was stopped before the test mode was set by the mode setting means M4.

In addition, judging from the predetermined conditions mentioned here and the fact that a predetermined time has passed since the test mode applying means M5 was activated in the test mode, and that the vehicle has reached the running state based on the steering, vehicle speed, shift position, etc. Various conditions can be considered, such as:

[Example] Next 1: A driving device for a piezoelectric actuator for a vehicle as an example of the present invention will be described based on the drawings. This driving device for a piezoelectric actuator for a vehicle is used in a damping force control device that adjusts the damping force of a variable damping force type shock absorber incorporating a piezoelectric body.

Figure 2 is a schematic diagram showing the overall configuration of this damping force control device, Figure 3 (A) is a diagram showing the overall configuration with the shock absorber partially cut away, and Figure 3 (B) is a diagram showing the overall configuration of the shock absorber. FIG. 3 is an enlarged cross-sectional view of main parts.

As shown in FIG. 2, 1: Table 11 of the vehicle damping force control device of this embodiment Variable damping force shock absorber (hereinafter referred to as
2FL (simply called shock absorber).

2 FR, 2 RL, 2 RRl, and an electronic control device 4 connected to each of these shock absorbers and controlling the damping force thereof.

Shock absorber 2FL, 2FR, 2RL,
2RR1 As described above 1:, Shock absorber 2
FL, 2 FR.

2 RL, 2 A piezo load sensor that detects the damping force acting on RR, and a shock absorber 2FL, 2
Each set includes a piezo actuator that switches the damping force of FR, 2RL, and 2RR.

In addition, each shock absorber 2 FL, 2 FR, 2
R.L.

2 RRl table Left and right front and rear wheels 5 FL, 5 F
R, 5RL, 5RR suspension lower arm 6FL, 6FR, 6RL, between 6RR and vehicle body 7 1 mm coil spring 8FL, 8 FR, 8R
It is attached together with L and 8 RR.

Next, each of the above-mentioned shock absorbers 2 FL, 2 F
R.

The structures of 2 RL and 2 RR will be explained. In addition, each of the above shock absorbers 2 FL, 2 FR, 2RL,
Since the structures of all 2 RRs are the same, the shock absorber 2FL on the left front wheel Sr1 side will be explained here as an example. In addition, in the following explanation, the subscript (FL) of the code attached to each member is 1.

FR, RL, RR) may be omitted as necessary.

Shock absorber 2 (1 as shown in Figure 3(A))
: At the lower end of the cylinder 11 side, it is fixed to the suspension lower arm 6 via the axle side member] 1a.Meanwhile, at the upper end of the rod 13 inserted through the cylinder 11, it is fixed to the axle side member via the bearing 7a and the vibration isolating rubber 7b. It is fixed to the vehicle body 7 together with a coil spring 8.

1 inside the cylinder 11 and an inner cylinder 15 connected to the lower end of the rod 13. Connecting member 16. A cylindrical member 17;
A main piston 18 that is slidable along the inner surface of the cylinder 11 is disposed.

The main piston 181 screwed to the cylindrical member 17 with a nut 19 connects the inside of the cylinder 11 to the first liquid chamber 21.
and a second liquid chamber 23, and the hydraulic oil flow rate between both liquid chambers 21 and 23 is regulated by fixed orifices 18a and 18b on the extension side and contraction side, thereby damping the normal damping characteristics of the shock absorber 2. Set to a state of great strength (hard).

1: as shown in Fig. 3 (A) and (B).

A piezo load sensor 2 is an electrostrictive element laminate in which thin plates of piezoelectric ceramics are laminated on an internal cylinder 15 with electrodes in between.
5 and a piezo actuator 27 to detect the magnitude of the damping force acting on the shock absorber 2.
(d) piston 3] 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 in the position shown in FIG. 3(B) (origin position) moves in the direction B in the figure, the first liquid chamber 21
The sub-flow path 16c connected to the sub-flow path 39b of the bushing 39 connected to the second liquid chamber 23, and the flow path 1 in the cylindrical member 17
7a, and the first liquid chamber 21 and the second liquid chamber 21 are in communication with each other.
The flow rate of hydraulic oil flowing between the liquid chamber 23 and the liquid chamber 23 increases. In other words, when the shock absorber 2 (air piezo actuator 27) expands due to the application of high voltage, its damping characteristics are switched from the state of high damping force (hard) to the damping power factor (soft) side, and when the electric charge is discharged and the piezo actuator 27 contracts, the damping characteristics change. to return to the state of high damping force (hard).

In order to keep the amount of hydraulic oil in the oil-tight chamber 33 constant, 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.

In addition, the partition wall 41a of the spool 41 has an oil passage 41d h (
The annular groove 40 of the spool 41 is provided with a lower communication hole 41e having a diameter larger than the diameter of the oil passage 41d.

The shock absorber 2 is equipped with a slidable plate valve 45 in an end space 39c following the sub-flow passage 39b, and the sliding speed of the main piston 18 in the cylinder 11 corresponds to the oil amount 45a formed in the plate valve 45. It is adjusted according to the flow direction of the hydraulic oil passing through the large-diameter oil amount 45b.

Next, the electronic control device 4 that switches and controls the damping force of the shock absorber 2 described above will be explained using FIG. 4.

This electronic control device 4 includes a steering sensor 50 for detecting the steering angle of a steering wheel (not shown), a vehicle speed sensor 51 for detecting the running speed of the vehicle, and a vehicle speed sensor 51 for detecting the running speed of the engine as sensors for detecting the running state of the vehicle. A shift position sensor 52 that detects the shift position of a transmission (not shown) that changes gears and outputs an output, and a stop lamp switch 53 that issues a signal when a brake pedal (not shown) is stepped on.
, a test switch 54 that is operated when performing a damping force test, and a test mode changeover switch 55 that specifies the test mode (hard or soft) are connected, and the detection signals of each sensor and switch are It is input to the electronic control device 4.

An electronic control device 41 that outputs a control signal to the piezo actuator 27 described above based on these detection signals and the detection signals of the piezo load sensor 25 of each shock absorber 2;
t, CPU 4 a, ROM 4 b.

The input section 4e is configured as a logic operation circuit centering around the RAM 4c and is connected to these components via a common bus 4d.
And input pressure with the outside is performed by the output part 4f.

1 table for electronic control unit 4 In addition, piezo load sensor 25
The damping force detection circuit 56 and the steering sensor 50 . a waveform shaping circuit 57 connected to the vehicle speed sensor 51;
A high voltage application circuit 58 connected to the piezo actuator 27, an output circuit 60 that outputs lighting current to a lamp 59 for damping force test notification, and a voltage boosting battery 61 that outputs a drive voltage for driving the piezo actuator. A so-called switching regulator type high voltage power supply circuit 62,
A power source 64 and the like that transforms the voltage of the battery 61 to generate an operating voltage (5 V) for the electronic control device 4 is provided. Then, a shift position sensor 52, a stop lamp switch 53. Test switch 54. Test mode selector switch 55. Damping force detection circuit 56. The waveform shaping circuit 57 has an input section 4 e I:.

High voltage application circuit 58. Output circuit 60. High voltage power supply circuit 6
2 are respectively connected to the output section 4f.

Note that an ignition switch 63 is provided between the battery 61 and the power source 64.

The damping force detection circuit 56 includes each piezo load sensor 25FL,
25 FR, 25 RL, and 25 RR, each detecting circuit (friend) detects the current flowing through the piezo load sensor 25 according to the acting force that the shock absorber 2 receives from the road surface. CP in terms of damping force and damping force change rate of absorber 2
It is configured to output to U4a. Therefore, C.P.
U 4 a 1. t, Based on the high force signals from the damping force detection circuit 56 and the waveform shaping circuit 57 that shapes and outputs the detection signal of the steering sensor 50 etc. into a signal suitable for processing in the CPU 4a, it is possible to determine the road surface condition and the running of the vehicle. The state and the like are determined, and a control signal is output to the corresponding high voltage application circuit 58 in order to switch the damping characteristics of the shock absorber 2 according to the result.

A high voltage application circuit 58 receives a high voltage from a high voltage power supply circuit 62 that outputs a drive voltage for driving the piezo actuator (Table 1). , the piezo actuator 27 is driven, and the damping force switching of the shock absorber 2 is performed in accordance with the damping force switching signal.To explain in more detail, the CPU 4
When a low level signal is input as a damping force switching signal from a, a high voltage V500 is applied to extend the piezo actuator 27, and conversely, when a high level signal is input as a damping force switching signal, a negative voltage V is applied.
-too, and apply it to the piezo actuator 27.
is configured to contract.

Therefore, when the damping force characteristics of each shock absorber 2 (upper) are extended by applying a high voltage to the piezo actuator 27 (as shown in FIG. 3),
The flow rate of the hydraulic oil flowing between the first liquid chamber 21 and the second liquid chamber 23 in the shock absorber 2 increases, resulting in a damping power factor (soft), and the charge is discharged by the negative voltage, causing the piezo actuator to When 27 is contracted, 1. t,
It becomes a damping blade hole (hard) because the hydraulic oil flow rate decreases.

Next, the damping force control performed by the vehicle damping force control device 1 of this embodiment having the above-described configuration will be explained based on the flowchart of FIG. 5.

FIG. 5 (1) shows a damping force control routine that is repeatedly executed by the electronic control device 4 from when the ignition switch 63 is turned on until it is turned off.

As shown in FIG. 5, first the ignition switch 63
When turned on, clears the internal register of CPU4a,
Initial processing such as resetting the flag set in the processing described later is performed (step 100), and then the voltage boosting in the high voltage power supply circuit 62 is completed and the piezo actuator 27
In step 110), it is determined whether the condition is sufficient to drive the ignition switch 63 based on the elapsed time since the ignition switch 63 was turned on, and the system waits until the voltage increase is completed.

When it is determined that the voltage boosting is completed (step 120, whether or not it is time to perform a damping force test is determined based on the ON signal output from the test switch 54), if this signal is in the OFF state, it is not the time to perform a damping force test. Therefore, the process moves to step 130 and subsequent steps for normal damping force switching processing, that is, switching the damping force according to the running state of the vehicle.On the other hand, if the damping force is in the on state, the process moves to step 160 since it is during a damping force test.

In particular, this test switch 54 is operated by a person conducting the test or the like.

If it is determined in step 120 that it is not the time for the damping force test, reset the counter value TCH of the counter representing the elapsed time since the start of the damping force test to the value O.Step 1
30), reset the test prohibition flag FD indicating that the damping force test will not be performed (step 140). After resetting the test prohibition flag FO, the damping force of the shock absorber 2 is switched (step 150).
, - Once this process is finished, the process is repeated from step 110. Since this damping force switching process is well known, we will only explain the outline of the internal process.

That is, the steering sensor 50. The driving state (steering angle θ) is determined based on the detection signal from the vehicle speed sensor 51 or the like.

vehicle speed S, etc.) and the road surface condition based on the detection signal from the damping force detection circuit 56, and outputs a low level or high level control signal to the high voltage application circuit 58 according to the result to drive the piezo actuator 27. The damping force of the shock absorber 2 is changed to soft or hard by expanding and contracting. In this way, the damping force of the shock absorber 2 is switched depending on the road surface condition and the like.

If it is determined in Step 20 that it is time to execute a damping force test based on the ON signal from the test switch 54, check whether the test prohibition flag FO, which indicates that the damping force test will not be executed, is in the reset state or the counter value T CHK is the predetermined value T
Is the value less than 0?

A determination is made as to whether the vehicle speed VF calculated from the detection signal of the vehicle speed sensor 51 is lower than a predetermined vehicle speed VFO (for example, 5 km/hour) (steps 160, 170, 1).
80). That is, it is determined in conjunction with the determination in step 120 whether or not the conditions for executing the damping force test are satisfied.

Each of the above steps 160, 170. If all the judgments corresponding to that step are affirmative at step 180 (all the execution conditions for the table damping force test are met, then the counter value TC) is incremented by the value 1 (step 190). , it is determined whether the test mode of the damping force test to be executed is a hard mode in which the damping force is switched from soft to hard or a soft mode in which the damping force is switched from hard to soft, based on the output signal from the test mode changeover switch 55 (step 20o). .

A signal indicating that the CPLJ 4a is in the hard mode is input from the test mode selector switch 55 (Dai). A negative voltage is forcibly applied to the piezo actuator 27 for a short period of time to contract the piezo actuator 27 and return the spool 41 to the home position. (Fig. 3 (B)), the damping force of the shock absorber 2 is switched from soft to hard, and fixed in the hard state (step 210).At this time, the damping force switching state and the fixed hard state are The state of maintenance, etc. will be tested.

Also, if a signal indicating soft mode is input (soft mode)
A voltage of several hundred V is forcibly applied to the piezo actuator 27 to extend the piezo actuator 27, and the spool 4
1 from the home position, and by increasing the flow rate of the hydraulic oil flowing between the first liquid chamber 21 and the second liquid chamber 23, the damping force is switched from pigeon to soft, and further 1:, the voltage is changed. The application is continued and the damping force is fixed in the soft state (step 220). At this time, the switching state of the damping force and the manner in which the fixed soft state is maintained are tested.

In this way, after steps 210 and 220 are executed (the process from step 110 is repeated again. Therefore, if the test switch 54 is in the on state (the front test mode continues), the counter value T CHK is incremented during that period. be exposed.

For this reason, the counter value T CHK may become a predetermined value of 10 or more with the test switch 54 in the on state, or the vehicle may enter a running state with the test switch 54 in the on state and the vehicle speed VF may exceed the predetermined vehicle speed VFO. Then (steps 170, 180), it is determined that the damping force test execution condition is not satisfied, and a value 1 is set to the test prohibition flag FO indicating that the damping force test will not be executed (step 2).
30).

In this routine after the test prohibition flag FO is set to the value 1 in this way (step 160), it is determined that the test prohibition flag FO is set.

After the test prohibition flag FO is set in step 230, the cPU 4a outputs a lighting command signal to the output circuit 60, and the output circuit 60 energizes the lamp 59: lighting current to light the lamp 59 for damping force test notification. (Step 240), this lamp 59 (Y) Even though the predetermined time has passed after the test execution or the vehicle is already in a running state and the damping force test is no longer being executed (Steps 170 and 180), the test The switch 53 is used to notify that the damping force test is still being performed (step 120).The lamp 59, which was turned on once, remains lit until the ignition switch 61 or the test switch 54 is turned off. Continue.

Then, following the lighting of the lamp 59, as described above,
The damping force of the shock absorber 2 is switched according to the running state of the vehicle (step 150).

As explained above, when testing the damping force switching of the drive device of the vehicle piezoelectric actuator of this embodiment, that is, the damping force control device 1 and the shock absorber 2, the test switch 54 operated by the test person etc. If the damping force test is turned on, the damping force test will be carried out immediately. When it is determined that there is no need to continue the test state of the soft mode and hard mode (steps 170 and 180), the test switch 5
4 is still in the ON state, the test mode is canceled, the damping force test is forcibly stopped, and the normal damping force switching E is executed.

As a result, even if the person conducting the test forgets to turn off the test switch 54 after completing the test.

The high voltage application that was forcibly applied in the test mode is automatically canceled, and the damping force is then suitably switched depending on the condition of the road surface when the vehicle is running. In addition, if the vehicle remains stopped (see table), the damping force state is based on the vehicle being stopped, and no high voltage is applied and no electric shock or leakage occurs.

In addition, even if you forget to cancel the test mode after executing the damping force test, if the execution condition is not satisfied (see above), the lamp 59 is configured to notify you of this, so the test switch 54 remains on. It can be easily determined that the

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. . For example (2), it goes without saying that it can be applied not only to the above-mentioned shock absorber but also to drive devices for various vehicle actuators such as actuators for pilot injection.

Effects of the Invention As detailed above, when performing a drive test that is essential when using a piezoelectric actuator for a vehicle according to the present invention, when an external operation is performed by a tester, etc. Immediately execute this drive test, and if a predetermined condition, such as the passing of sufficient time for the vehicle to run on open ground, is established after the test is executed once, the high voltage applied during the drive test is no longer applied. It is determined that there is no need to continue the test, and the drive test is forcibly canceled.

As a result, with the drive device for a piezoelectric actuator for a vehicle according to the present invention, the high voltage application for testing after the drive test is automatically canceled without being manually canceled. There is no risk of unforeseen driving conditions of the piezoelectric actuator for a vehicle when the vehicle is running or leakage of electricity when the vehicle is stopped, which was conventionally recognized after a drive test.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the basic configuration of the present invention. FIG. 2 is a schematic diagram showing the overall configuration of a damping force control device when one embodiment of the present invention is used in the damping force control device. Figure (A) is a partial cross-section showing the structure of the shock absorber of the damping force control device. Figure 3 (B) is an enlarged cross-section of the main part of the shock absorber. Figure 4 shows the configuration of the electronic control device of this embodiment. Block Doctor FIG. 5 is a flowchart showing the damping force switching routine. 2FL, 2FR, 2RL, 2RR...-variable damping force shock absorber 4...Electronic control device 25F
L, 25FR, 25RL, 25RR... Piezo load sensor 2 7 FL, 2 7 FR, 27RL,
2 7 RR...Piezo actuator 51...Vehicle speed sensor 54...Test switch 55
...Test mode selection switch

Claims (1)

[Scope of Claims] 1. A piezoelectric actuator using a piezoelectric body that expands and contracts in response to an applied voltage; and boosting means that boosts the output voltage of a power source mounted on a vehicle to generate a drive voltage for the piezoelectric actuator. , a drive device for a piezoelectric actuator for a vehicle, comprising a driving voltage applying means for applying a driving voltage generated by the boosting means to the piezoelectric body at a desired timing, the piezoelectric actuator being driven when an external operation is performed. mode setting means for setting a mode to a test mode; test mode applying means for applying a drive voltage of the step-up means to the piezoelectric body while the test mode is set by the mode setting means; and testing by the setting means. 1. A drive device for a piezoelectric actuator for a vehicle, comprising test mode canceling means for canceling the setting of the test mode when a predetermined condition regarding time or driving state is satisfied after setting the mode.