JPH02176121A - Electrostriction type actuator driving device - Google Patents

Abstract

PURPOSE:To improve reliability by stopping the excitation to a flyback type high-voltage generating means when a primary current cutoff means is not operated longer than the preset period due to the abnormality of an electrostriction type actuator. CONSTITUTION:The pressure from a passage repeatedly increased with the pressure is applied to an electrostriction type actuator 4, and the voltage is generated in response to the pressure value. When the voltage value detected by an electronic controller 7 becomes the preset value or above, a primary current cutoff means cuts off the primary current of a flyback type high-voltage generating circuit 5, and the high-voltage is generated in a secondary side circuit and applied to the electrostriction type actuator 4. When the primary current cutoff means is not operated longer than the preset period, an excitation control means stops the excitation to the flyback type high-voltage generating circuit 5. As a result, no current flows in the flyback type high-voltage generating circuit 5, and the breakage caused by excess excitation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] The present invention relates to an electrostrictive actuator drive device, and more specifically, a device for detecting a voltage generated in an electrostrictive actuator and driving it to extend. Regarding.

[Prior Art] Conventionally, it has been known to operate various devices by driving an electrostrictive actuator to expand and contract.

For example, JP-A-61-25925 or JP-A-62
There is a pilot injection control device for a diesel engine that performs biloft injection control based on the voltage generated by an electrostrictive actuator, as disclosed in Japanese Patent No. 279234.

The amount of expansion and contraction of an electrostrictive actuator generally depends on the applied voltage. Therefore, in Japanese Patent Laid-Open No. 63-687, a device was developed to increase the amount of expansion and contraction of an electrostrictive actuator by applying a high voltage using a flyback type high voltage generator.
It is proposed in No. 46. In such a device, in order to generate the high voltage necessary for operation, it is necessary to supply sufficient current to the boosting primary winding of the flyback type high voltage generator.

[Problems to be Solved by the Invention] In such a conventional device, the timing for cutting off a portion of the current in the flyback type high voltage generator was determined by detecting the voltage generated by the electrostrictive actuator.
If the voltage generated from the electrostrictive actuator is not detected due to an abnormality or the like, no high voltage is applied to the piezoelectric element on the secondary side, and the operation of the actuator is automatically stopped.

However, in this case, current continues to flow through the flyback type high voltage generator, which may cause problems such as overheating and damage to resistors, transistors, etc. used in the primary circuit.

Therefore, the present invention has been made to prevent such problems and provide a highly reliable electrostrictive actuator drive device.

Structure of the Invention [Means for Solving the Problems] As illustrated in FIG. 1, the electrostrictive actuator drive device of the present invention includes an electrostrictive actuator M1 provided facing a flow path where pressure is repeatedly increased; The electrostrictive actuator M1 receives the pressure of the flow path.
A flyback comprising a voltage detection means M2 for detecting the voltage generated in the secondary circuit, and a step-up section for generating a high voltage in the secondary circuit by interrupting the primary current, and the electrostrictive actuator M1 is connected to the secondary circuit. and when the voltage detected by the voltage detection means M2 exceeds a predetermined value, the flyback type high voltage generation means M
In the electrostrictive actuator driving device, the primary current interrupting means M4 is configured to interrupt the primary current and apply a high voltage to the electrostrictive actuator M1. The present invention is characterized in that it includes an energization stopping means M5 that stops energizing the flyback type high voltage generating means M3 when the flyback type high voltage generating means M3 does not operate.

[Function] The electrostrictive actuator M1 is subjected to pressure from a flow path whose pressure increases repeatedly, and a voltage corresponding to the pressure value is generated. The voltage detection means M2 detects the voltage value generated in the electrostrictive actuator M1. When the voltage value detected by the voltage detection means M2 exceeds a predetermined value, the primary current cutoff means M4 cuts off the primary current of the flyback type high voltage generation means M3, and A high voltage is generated in the secondary circuit of the means M3, and the high voltage is applied to the electrostrictive actuator M1.

Here, if the primary current cutoff means M4 does not operate for a predetermined period of time, the energization control means M5 stops energizing the flyback type high voltage generation means M3. As a result, no current flows through the flyback type high voltage generating means M3, and excessive current flow is prevented.

[Embodiment] Next, an embodiment in which the electrostrictive actuator drive device of the present invention is implemented as a fuel injection control device for a diesel engine will be described. FIG. 2 shows the system configuration of this embodiment.

As shown in the figure, a diesel engine fuel injection control device 1 includes a diesel engine 2, a distribution type fuel injection pump 3 that pressurizes and pumps fuel to be supplied to the diesel engine 2, and a fuel injection pump 3 that is installed alongside the fuel injection pump 3. It consists of an electrostrictive actuator 4, a flyback high voltage generation circuit 5 that loads a high voltage to the electrostrictive actuator 4, and an electronic control unit (hereinafter simply referred to as ECU) 7 that controls these. There is.

The diesel engine 2 is provided with a fuel injection valve 15 to which fuel is supplied by the fuel injection pump 3 .

The fuel injection pump 3 includes a drive pulley 21 connected to the crankshaft (not shown) of the diesel engine 2 by a belt or the like, and a drive shaft 22 of the drive pulley 21.
The vane pump 23 is a fuel feed pump coupled to a vane pump 23, which sucks fuel from a fuel tank (not shown) by the driving force of the diesel engine 2. A plunger 27 is connected to the right end of the drive shaft 22 in the drawing via a coupling 25. A face cam 26 is integrally provided on the left end side of the plunger 27 in the drawing.

The face cam 26 is urged leftward in the figure by a spring 29, and a cam roller 31 is in contact with the cam surface 26a. The plunger 27 is connected to the drive shaft 22
Due to the riding motion of the cam surface 26a accompanying the rotation of the cam surface 26a, the cam surface 26a is reciprocated in the axial direction while rotating together with the drive shaft 22, thereby distributing and pumping fuel.

A block 33 is attached to the head of the housing 32 of the fuel injection pump 3. Further, a cylinder 2, into which the top of the plunger 27 fits, is attached to the block 33. Inside the block 33 is a plunger 2.
A pressurized chamber 34 is formed surrounded by the cylinder 7 and the cylinder 2. The plunger 27 includes a number of suction boats 35 corresponding to the number of cylinders of the diesel engine 2, and the housing 3
The fuel inside the cylinder 2 is sucked and pressurized inside the pressurizing chamber 34, and the pressurized fuel is distributed and supplied to each air cell via the distribution boat 36, which is also provided for the same number of cylinders. Further, a spill ring 3 is fitted around the plunger 27 so as to close the spill boat 37. The spill ring 38 is slidably adjusted along the plunger 27 by a well-known governor mechanism (not shown) to adjust the timing at which fuel pressurization ends. The fuel pressurized within the pressurization chamber 34 is delivered to a fuel supply passage 39a communicating with the distribution boat 36, a delivery valve 40a, and a fuel vibrator 41.
The fuel is supplied to the fuel injection valve 15 via the fuel injection valve 15.

The electrostrictive actuator 4 is configured by fitting a casing 51 and a piston 52 having a piezoelectric element 53 therein in a fluid-tight and slidable manner.

The electrostrictive actuator 4 is screwed onto the block 33 of the fuel injection pump 3 by a threaded portion 51a carved on the outer periphery of the tip of the casing 51. The tip of the casing 51 includes an upper end surface 52 of the casing 51° piston 52.
A variable volume chamber 55 surrounded by the block 33 and the variable volume chamber 55 is formed. The variable volume chamber 55 communicates with the pressurizing chamber 34 of the fuel injection pump 3 via a communication hole 56 .

The piezoelectric element 53 has a structure in which a plurality of disc-shaped members made of PZT, which is a ceramic material whose main component is lead zirconate titanate, is laminated with electrodes interposed therebetween, and an electric charge is loaded through the signal line 54. Then, the piston 52 extends upward as shown in the figure.
slide in the same direction.

As a result, the volume of variable volume chamber 55 decreases. - On the other hand, when the electric charge is removed via the signal line 54, the piezoelectric element 53 contracts in the opposite manner to the above, causing the piston 52 to slide downward in the figure. As a result, the volume of the variable volume chamber 55 increases. Note that the fuel pressure inside the variable volume chamber 55 acts on the piezoelectric element 53 as a compressive force. Therefore, the piezoelectric element 53 generates a voltage corresponding to the strain caused by the compressive force. EC
U7 can detect this voltage level via signal line 54.

As shown in FIG. 3, the flyback type high voltage generation circuit 5 includes, as a primary side, a partial winding 61. which is connected in series with an on-board variation 60. It includes a primary transistor 2 and a resistor 63 for current detection, and a primary measurement current control circuit 64 is connected to the base of the primary transistor 20 to keep the current value flowing through the primary winding 61 constant. . The primary side constant current control circuit 64 provides a pulse signal to the partial side transistor RO 2 based on a control signal from the ECU 7 to control energization to the primary winding 61 . Further, the current value flowing through the primary winding 61 is controlled by the EC through the primary measurement current control circuit 64.
Sent to U7.

On the secondary side of the flyback type high voltage generation circuit 5, a piezoelectric element 53. Secondary winding 65. A secondary side transistor 66 and a current detection resistor 67 are connected in series. In addition,
A diode is connected in parallel to the transistor 66 and the resistor 67.

In addition, in order to control the current value flowing through the secondary winding 65,
A secondary measurement current control circuit 69 is connected to the base of the secondary side transistor 66. The secondary measurement current control circuit 69 provides a pulse signal based on a control signal from the ECU 7 to the secondary side transistor 66, and also sends a current value flowing through the secondary winding 65 to the ECU 7.

In addition to the above configuration, the fuel injection control device 1 includes various detectors for performing various controls.

The detector is the drive pulley 2 of the fuel injection pump 3.
The passage of the protrusion 21a of the diesel engine 2 is detected.
a reference signal generation sensor 71 that detects the fuel injection stroke of each cylinder; and a pulse gear 2 provided on the drive shaft 22.
A rotational speed sensor 7 detects the rotational speed Ne of the diesel engine 2 from the pulse interval generated by the passage of the tooth row No. 4.
2. A water temperature sensor 73 that detects the cooling water temperature of the diesel engine 2, a block temperature sensor 74 that detects the wall surface temperature of the cylinder block of the diesel engine 2, and a starter signal switch 75 that outputs a starter signal when starting the diesel engine 2. Be prepared.

The ECU 7 described above includes a well-known CPU 7a, a ROM 7b,
It includes a RAM 7e, a timer 7d, a human output section 7f, and a common bus 7e that interconnects these, and is configured as a logic operation circuit. The detection signals of the above-mentioned sensors, Sui, Sochi, etc. and the piezoelectric element voltage V PZT of the piezoelectric element 53 are manually inputted to the CPU 7a via the human output section 7f;
U7a outputs a control signal to the flyback type high voltage generation circuit 5 via the human output section 7f.

Here, based on the timing chart in Figure 4 (a),
The operation of the electrostrictive actuator 4 will be explained. When the ECU 7 sends a signal to the primary constant current control circuit 64, the primary transistor 2 turns on, and the primary winding 61
The current force 9 begins to bald (f-11), then the constant current value ■1
(H2).

In this state, the piezoelectric element 53 is not applied with a voltage by the flyback type high voltage generation circuit 5, but is instead subjected to compression force due to the pressure increase in the variable volume chamber 55 due to the fuel pumping operation of the plunger 27. Therefore, the piezoelectric element voltage V PZT
is occurring (82-H3). Piezoelectric element voltage V PZ
T is proportional to the pressure inside the variable volume chamber 55, and when this piezoelectric element voltage V PZT reaches a predetermined reference voltage value VTH corresponding to the fuel injection pressure, a turn-off signal is sent to the primary side transistor Ro 2, and the primary winding Power to 61 is cut off (
H3). As a result, a high voltage is generated in the secondary circuit, and the high voltage is applied to the piezoelectric element 53. The piezoelectric element 53 expands in proportion to the applied voltage value. Therefore, the volume of the variable volume chamber 55 decreases, the internal pressure increases accordingly, and pilot injection is started (H4). After the predetermined application time T1 has elapsed, the ECU 7 activates the secondary transistor 69.
A turn-on signal is applied, and the current in the secondary circuit flows in the direction indicated by arrow I2 in FIG. 3 (H4). Therefore, the charge stored in the piezoelectric element 53 is dissipated, and the piezoelectric element 53 is correspondingly reduced in size. As a result, the variable volume chamber 55
The volume of the fuel increases, its internal pressure decreases, and the pilot injection ends (H5). The secondary measurement current control circuit 69 is
Initially, constant current control is executed, but after the fall time T3 has elapsed, constant current control is stopped and the secondary side transistor 66 is brought into a short-circuited state. After the short-circuit time T2 until the secondary current field becomes zero, the ECU 7 switches the secondary transistor 6
As a result, the secondary side transistor 66 is turned off, and the piezoelectric element 53 is further compressed by the internal pressure of the variable volume chamber 55, which has risen again due to the pumping operation of the plunger 27. While contracting, a voltage corresponding to the compression force is generated (H7). At this point, fuel main chant q1 is executed (88-H9)
. After that, the spill boat 37 is opened and the variable volume chamber 5
When the pressure inside 5 decreases, main fuel injection ends (H9
). Note that at time H7, as shown in FIG. 4(b), the communication hole 56 is shut off, so the piezoelectric element voltage V PZT remains at a constant value while the main fuel injection is being performed.

The ECU 7 repeatedly executes the above control, and in this embodiment, a predetermined interval T is elapsed between turning on the primary transistor 2 and turning it off again.
It is executed repeatedly based on D. Predetermined interval T
O is changed depending on the operating state of the diesel engine 2, and is adjusted with reference to detection results from various detectors so as to achieve optimal fuel injection. For example, an idle state, a high-speed operating state, etc. are determined from the detected values of the rotational speed sensor 72 and water temperature sensor 73, and in the high-speed operating state, adjustments such as shortening the predetermined interval TO are performed.

Next, fuel injection control processing, which is a special effect of this embodiment, will be explained based on the flowchart of FIG. 5 and the timing chart of FIG. 6.

First, energization to the primary transistor 2 is started at time HIO. Thereafter, when the voltage generated by the piezoelectric element 530 reaches the reference voltage value VTR at time fH1, the primary current is cut off, the timer is reset, the alarm is turned off, and time measurement by the elapsed time counter T C0LINT is started (step 200 ). This elapsed time counter T C0LINT
The following various judgments are performed based on the following. counter TC
Timing continues until the value of OυNT reaches the predetermined interval TO (step 201). Then time H1
2, the value of the counter TCOUNT reaches the predetermined interval TO.
When the current is reached, the primary current starts flowing (step 20).
2).

Next, a prohibition control loop is entered, and the counter TCOtJ
It is determined whether the NT's time has advanced and reached the prohibited time TKINSI (step 203). Here, the prohibition time T
KINS+ is a value larger than the predetermined interval TD,
It is set to a value larger than the value taking into account the time (813-H12 in FIG. 6) until the pressure in the variable volume chamber 55 reaches the fuel injection pressure after the predetermined interval TO has elapsed in the fuel injection cycle. Initially when proceeding to step 203, since INS+ is TCOLINT<T,
Proceeding directly to step 204, the piezoelectric element voltage VPZT detected from the piezoelectric element 53 is the reference voltage fliVT).
It is determined whether the value has become 1 or more. Even in the normal state, since VPZT<VTH between time H12 and time H13, the processes of steps 203 and 204 are repeated.

When VPZT=VT)l at time H13, an affirmative determination is made in step 204 and the process returns to step 200, where the next fuel injection control is executed again. On the other hand, if there is any abnormality in the piezoelectric element 53, the VPZ
T=VTH does not hold, and the prohibition time TKINsl elapses without the piezoelectric element voltage V PZT reaching the reference voltage value VT)I. As a result, at time I (15), the judgment in step 203 becomes a negative judgment, and the process now proceeds to step 205 to stop energizing the primary side circuit. That is, the primary side transistor 2 is turned off. After that, the piezoelectric element 53 is alerted that there is an abnormality (step 206).

Thereafter, until an affirmative determination is made in step 204, the prohibition control loop processing is repeatedly executed to prevent damage to the flyback type high voltage generation circuit 5. Even during execution of the prohibition control loop, when the abnormality recovers, a voltage corresponding to the compressive force is generated in the piezoelectric element 53, and V as shown at time H16.
PZT≧VTH.

This time, the determination in step 204 is affirmative, and the process exits the prohibition control loop and returns to step 200. Immediately after recovery, pilot injection is not performed because the primary current is not flowing.

Here, depending on the timing at which the communication hole 56 is cut off, the piezoelectric element voltage VPZT may reach the reference voltage value VTI (as shown at time H20), but the primary side transistor 2 is not originally energized. Therefore, even if a signal to cut off the primary current is given, high voltage will not be generated in the secondary circuit, and fuel injection will not be affected in any way.

In addition, in this embodiment, the timing of the predetermined interval TO is configured to start from the time when the current to the primary side transistor 2 is cut off, but the time measurement may start from the time when the power supply to the primary side transistor 2 starts. .

As explained above, according to this embodiment, the piezoelectric element voltage V
If the state in which PZT does not reach the reference voltage value VTH continues for a predetermined period or more, it is determined that there is an abnormality in the piezoelectric element 53, and the pilot injection control based on the piezoelectric element voltage VPZT is not performed. , it is possible to prevent the flyback type high voltage generation circuit 5 from being damaged. Therefore, there is no problem even if the current flowing through the secondary side of the flyback high voltage generating circuit 5 is increased in advance in order to make the voltage generated in the secondary side circuit sufficiently high. Therefore, piezoelectric element 5
The amount of expansion and contraction of 3 can be easily increased by 51 degrees.

As a result, the amount of expansion and contraction of the electrostrictive actuator 4 can be sufficiently large, and the pressure inside the variable volume chamber 55 can be greatly changed, so that extremely highly effective pilot injection can be achieved.

Further, pilot injection control and control for preventing damage to the flyback type high voltage generation circuit 5 are both performed using the piezoelectric element 53.
Since the control is executed based on the piezoelectric element voltage V PZT of Damage to the buck type high voltage generating circuit 5 can be prevented. Such damage occurs when
This is a case where the primary current cutoff to the flyback type high voltage generation circuit 5 is not executed.On the other hand, in the electrostrictive actuator drive device of this embodiment, if this instruction to cut off the primary current itself is abnormal, this abnormality occurs. This effect can be obtained because the structure is configured to make a judgment based on the following.

Furthermore, when the piezoelectric element 53 is abnormal, even after the power supply is stopped and an alarm is issued (step 205 → step 206),
The piezoelectric element recovers from the abnormality again in step 204, and it is determined whether the piezoelectric element voltage VPZT has reached the reference voltage value VTI (or not) again, and the loop processing from step 203 onwards is repeated, so that recovery from the abnormality is possible. In this embodiment, after the primary side transistor 2 is turned off, the primary current is not applied until the predetermined interval TO has elapsed, so during that time the piezoelectric element voltage Even if VPzT reaches the reference voltage value VTH, there is no malfunction of the electrostrictive actuator 4, and power consumption can be saved since unnecessary energization is not performed.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment. For example, the present invention is not limited to such an embodiment. It goes without saying that the present invention can be applied to various devices that utilize the present invention, and can be implemented in various ways without departing from the gist of the present invention.

As explained above, according to the device of the present invention, if the primary current cutoff means does not operate for more than a predetermined time due to an abnormality in the electrostrictive actuator, the flyback type high voltage generation means is operated. Since the current is turned off, damage caused by excessive current can be prevented. Therefore, in order to generate a sufficiently high voltage necessary for suitable control by the electrostrictive actuator,
There is no problem even if the current applied to the flyback type high voltage generating means is increased in advance. As a result, a sufficient amount of expansion and contraction of the electrostrictive actuator could be achieved, and suitable control became possible. In addition, since the judgment is made based on the operating state of the primary current cutoff means, flyback type high voltage generation can occur not only when there is an abnormality in the electrostrictive actuator itself, but also when normal control is not performed due to a disconnection of the signal line, etc. Damage to the means can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram illustrating the configuration of the present invention, Fig. 2 is a system configuration diagram of an embodiment of the present invention, Fig. 3 is a circuit diagram showing the configuration of the high voltage generation circuit, and Fig. 4 ( A) is a timing chart showing the relationship between the driving state of the circuit and pilot injection, FIG. FIG. 6 is a flowchart showing the procedure, and is a timing chart illustrating control states in which the electrostrictive actuator changes from normal to abnormal to recovery from abnormality. Ml...Electrostrictive actuator M2...Voltage detecting means M3...Flyback type high voltage generating means M4...Primary current interrupting means M5...Electrification control means 1...Fuel injection of diesel engine Control n device 2・
...Diesel engine 3...Fuel injection bomb 4...Electrostrictive actuator 5...Flyback type high voltage generation circuit 7...Electronic control unit (ECU) 53...Piezoelectric element 54・・・
・Signal line 60...Discrepancy

Claims (1)

[Scope of Claims] An electrostrictive actuator provided facing a flow path where pressure repeatedly increases; voltage detection means for detecting a voltage generated in the electrocup type actuator in response to pressure in the flow path; flyback type high voltage generation means comprising a step-up section that generates a high voltage in a secondary circuit when current is interrupted, and the electrostrictive actuator is connected to the secondary circuit; and a voltage detected by the voltage detection means. an electrostrictive actuator drive comprising: a primary current cutoff means for cutting off the primary current of the flyback type high voltage generation means and applying a high voltage to the electrostrictive actuator when the voltage exceeds a predetermined value; An electrostrictive actuator drive device, characterized in that the device comprises energization stop means for stopping energization to the flyback type high voltage generation means when the primary current cutoff means does not operate for a predetermined period of time. .