CN104500298A - Driving current control circuit of piezoelectric ceramic diesel injector - Google Patents

Abstract

The present invention relates to a driving current control circuit of a piezoelectric ceramic fuel injector of a diesel engine, wherein the driving current control circuit of a piezoelectric ceramic fuel injector of a diesel engine includes a first processor and a piezoelectric ceramic actuator; the piezoelectric The high-voltage end of the ceramic actuator is connected to the source end of the high-voltage charging switch tube T1 and the drain end of the discharge switch tube T2, and the source end of the discharge switch tube T2 is grounded; the low-voltage end of the piezoelectric ceramic actuator is connected to the The working current sampling of the piezoelectric ceramic actuator is connected to the sampling threshold processing circuit, the sampling threshold processing circuit is connected to the current control circuit, and the current control circuit is respectively connected to the gate terminal of the high-voltage charging switch tube T1 and the discharge switch through a logic driving circuit. The gate terminal of the tube T2 is connected; the invention has a compact structure, can realize precise control of the driving current, ensure the consistency of the driving current, reduce switching loss, and improve the reliability of the electric control system.

Description

Driving Current Control Circuit of Diesel Engine Piezoelectric Ceramic Fuel Injector

technical field

The invention relates to a driving current control circuit, in particular to a driving current control circuit of a diesel engine piezoelectric ceramic fuel injector, belonging to the technical field of diesel engine piezoelectric ceramic fuel injection systems.

Background technique

For diesel injectors, Siemens was involved in the piezoelectric system drive earlier, and first proposed the basic drive structure; BOSH combined with the vehicle system, proposed many optimization schemes for actual control, etc.; current control schemes generally use variable PWM drive, For controlling the driving process from small pulses to larger pulses, references such as US8074626B2, JP04615967B2; or variable duty cycle control PWM drive mode, references such as EP1772952B1. The current control method is basically directly coupled with PWM after hardware sampling and comparison. In extreme cases (such as high-speed multiple injection requirements) the heat loss of power devices is serious.

At present, due to the particularity of piezoelectric materials, foreign countries have successfully tackled key problems, and basically only need to do general protection and control of the large current of the actuator. Even if there is current control, the basic current control is realized through the voltage feedback based on the sampling resistor and the PWM control of the MCU, and the accuracy of the current control is limited. At present, domestic actuators cannot withstand high current impacts, and more precise control of the current is required. Some schemes also use sampling resistor feedback to control the current, but when the current is controlled at a lower value, the system loss is large, the heat is serious, there is no transition coupling of the latch, the switching frequency is high, the device heats up seriously, and the electromagnetic interference is relatively high. serious.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a driving current control circuit for piezoelectric ceramic fuel injectors of diesel engines, which has a compact structure, can realize precise control of the driving current, and ensure the consistency of the driving current. Reduce switching loss and improve the reliability of the electronic control system.

According to the technical solution provided by the present invention, the drive current control circuit of the piezoelectric ceramic fuel injector of the diesel engine includes a first processor and a piezoelectric ceramic actuator; the high voltage end of the piezoelectric ceramic actuator and the high voltage charging switch tube The source terminal of T1 is connected to the drain terminal of the discharge switch tube T2, and the source terminal of the discharge switch tube T2 is grounded; the low voltage terminal of the piezoelectric ceramic actuator is used for sampling the working current of the piezoelectric ceramic actuator The sampling threshold processing circuit is connected, and the sampling threshold processing circuit is connected with the current control circuit, and the current control circuit is respectively connected with the gate terminal of the high-voltage charging switch tube T1 and the gate terminal of the discharge switch tube T2 through the logic drive circuit;

The first processor is connected to the current control circuit, and can input a high-frequency capture enable signal to the current control circuit; when the operating current on the piezoelectric ceramic actuator does not match the preset current threshold in the sampling threshold processing circuit, the sampling threshold The processing circuit outputs a threshold current control trigger signal to the current control circuit, and the current control circuit can effectively capture the threshold current control trigger signal output by the sampling threshold circuit through the high-frequency capture enable signal, and the current control circuit controls the trigger signal output current according to the captured threshold current The control signal, the logic drive circuit adjusts the corresponding switching states of the high-voltage charging switch tube T1 and the discharge switch tube T2 according to the current control signal, so that the working current of the piezoelectric ceramic actuator matches the preset current threshold.

The first processor is connected to the sampling threshold processing circuit, and the first processor can transmit a current adjustment control signal to the sampling threshold processing circuit, so as to adjust the preset current threshold in the sampling threshold processing circuit through the current adjustment control signal.

The high-voltage end of the piezoelectric ceramic actuator is connected to the source end of the high-voltage charging switch tube T1 and the drain end of the discharge switch tube T2 through an inductance gating circuit, and the low-voltage end of the piezoelectric ceramic actuator is grounded through the sampling resistor R1. The sampling threshold processing circuit is connected to the sampling resistor R1 to collect the working current of the piezoelectric ceramic actuator through the sampling resistor R1; the first processor can input the inductance gating signal to the inductance gating circuit, and the inductance gating circuit is based on the inductance gating signal The value of the inductance connected to the piezoelectric ceramic actuator can be adjusted.

The sampling threshold processing circuit includes a current sampling circuit for sampling the working current of the piezoelectric ceramic actuator and a threshold control circuit for comparing the working current sampled by the current sampling circuit; the threshold control circuit has a preset A current threshold, when the sampled operating current does not match the preset current threshold, the threshold control circuit outputs a threshold current control trigger signal to the current control circuit.

The current control circuit includes a second processor and a latch. Both the second processor and the latch receive the threshold current control trigger signal output by the sampling threshold processing circuit, and the second processor simultaneously receives the threshold current control trigger signal output by the first processor. output high-frequency capture enable signal; under the action of the high-frequency capture enable signal, when the second processor receives the threshold current control trigger signal at the same time, the second processor can output the operating current control trigger signal to the latch, The latch outputs a current control signal according to the working current control trigger signal and the threshold current control trigger signal, so that the logic drive circuit can adjust the switching states of the high-voltage charging switch T1 and the discharge switch T2 according to the current control signal.

The logic drive circuit includes a first AND gate U1 and a second AND gate U2, an input end of the first AND gate U1 and an input end of the second AND gate U2 are connected to the output end of the current control circuit, and the first AND gate U2 is connected to the output end of the current control circuit. The other input end of the gate U1 is connected to the output end of the first processor to receive the high-voltage switch charging signal output by the first processor; the other input end of the second AND gate U2 is connected to the output end of the first processor, To receive the discharge tube work trigger signal output by the first processor; the output terminal of the first AND gate U1 is connected to the gate terminal of the high-voltage charging switch tube T1, and the output terminal of the second AND gate U2 is connected to the gate terminal of the discharge switch tube T2 ;

The first AND gate U1 can drive and turn on the high-voltage charging switch tube T1 according to the high-voltage switch charging signal output by the first processor, and can turn off the high-voltage charging switch tube T1 according to the current control signal output by the current control circuit; the second AND gate U2 can The discharge switch tube T2 is driven and turned on according to the discharge tube operation trigger signal output by the first processor, and the discharge switch tube T2 can be turned off according to the current control signal output by the current control circuit.

The output terminal of the current control circuit is connected with the first processor to output the current control signal to the first processor; the first processor can count the current control signal, and when the count value of the first processor reaches the preset value , the first processor can simultaneously turn off the high-voltage charging switch T1 and the discharge switch T2 through the logic driving circuit.

The inductance gating circuit includes an inductor L1 and an inductor L2, one end of the inductor L1 and the anode terminal of the diode D1, the cathode terminal of the diode D2, the drain terminal of the switching tube Q1, the source terminal of the high voltage charging switching tube T1 and the discharging switching tube T2 The drain terminal of the inductor L1 is connected to the anode terminal of the diode D3 and the cathode terminal of the diode D4, the anode terminal of the diode D2 and the anode terminal of the diode D4 are both grounded, the cathode terminal of the diode D1, the cathode terminal of the diode D1, The cathode terminals of the diode D3 are connected to the high voltage source VCC_BOOST; the gate terminal of the switch tube Q1 is connected to the output terminal of the first processor through the bootstrap circuit to receive the inductance gating signal output by the first processor; one end of the inductance L2 is connected to the The source terminal of the switching tube Q1 is connected to the cathode terminal of the diode D5, the other end of the inductor L2 is connected to the anode terminal of the diode D6, the anode terminal of the diode D5 is grounded, and the cathode terminal of the diode D6 is connected to the high voltage source VCC_BOOST.

Described second processor comprises CPLD processor U4 and inverter U3, and described inverter U3 is connected with the output end of sampling threshold value control circuit, and the output end of inverter U3 is connected with the input end of CPLD processor U4, The CPLD processor U4 also receives the high-frequency capture enable signal output by the first processor, and the CPLD processor U4 can output an operating current control trigger signal to the latch.

The sampling threshold processing circuit includes an amplifier U6, the non-inverting end of the amplifier U6 is connected to one end of the resistor R2, the inverting end of the amplifier U6 is connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R3 is grounded, and the resistor R3 is connected to the other end of the resistor R3. The other end of R4 is connected to the output end of the amplifier U6 and one end of the resistor R5, the resistor R5 is connected to one end of the resistor R11 through the resistor R10, the other end of the resistor R11 is connected to one end of the capacitor C1, the inverting end of the comparator U7, and the resistor R12 One end of the capacitor C1 is connected to the non-inverting end of the comparator U7, one end of the resistor R9 and one end of the resistor R8, the other end of the resistor R9 is connected to the DA module, and the other end of the resistor R8 is connected to the collector end of the transistor Q2 connection, the emitter end of the transistor Q2 is grounded, the base end of the transistor Q2 is connected to one end of the resistor R6 and one end of the resistor R7, and the other end of the resistor R7 is grounded; the other end of the resistor R12 is connected to the output end of the comparator U7 and one end of the resistor R13 And one end of the resistor R14 is connected, and the other end of the resistor R13 is connected with +3.3V voltage.

The advantage of the present invention is that the piezoelectric ceramic actuator is connected with the inductance gating circuit, and the inductance gating circuit adjusts the inductance value connected with the piezoelectric ceramic actuator through the inductance gating signal, thereby changing the working condition of the piezoelectric ceramic actuator. Time-to-time current conversion to achieve different current response times; the threshold control circuit can compare the operating current of the piezoelectric ceramic actuator with the preset current threshold, and can output a threshold current control trigger signal, and the first processor can adjust the threshold control circuit The preset current threshold within, so that the piezoelectric ceramic actuator can have different peak currents, so that the driving process is a gradual process, the second processor uses a CPLD processor, and the CPLD processor is under the action of the high-frequency capture enable signal To capture the threshold current control trigger signal, the latch latches the threshold current control trigger signal according to the working current control trigger signal and outputs the current control signal. The logic drive circuit uses two AND gates to realize high voltage charging through the current control signal The switch state control of the switch tube and the discharge switch tube can realize the precise control of the drive current, ensure the consistency of the drive current, reduce the switching loss, and improve the reliability of the electric control system.

Description of drawings

Fig. 1 is a structural block diagram of the present invention.

Fig. 2 is a schematic circuit diagram of the inductance gating circuit of the present invention.

Fig. 3 is a schematic circuit diagram of the current control circuit of the present invention.

FIG. 4 is a schematic circuit diagram of the sampling threshold processing circuit of the present invention.

Description of reference signs: 1-first processor, 2-inductance gating circuit, 3-piezoelectric ceramic actuator, 4-sampling threshold processing circuit, 5-current sampling circuit, 6-threshold control circuit, 7-current control circuit, 8-second processor, 9-latch, 10-bootstrap circuit, and 11-DA module.

Detailed ways

The present invention will be further described below in conjunction with specific drawings and embodiments.

As shown in Figure 1: In order to achieve precise control of the driving current, ensure the consistency of the driving current, reduce switching losses, and improve the reliability of the electronic control system, the present invention includes a first processor 1 and a piezoelectric ceramic actuator 3 The high-voltage end of the piezoelectric ceramic actuator 3 is connected to the source end of the high-voltage charging switch tube T1 and connected to the drain end of the discharge switch tube T2, and the source end of the discharge switch tube T2 is grounded; the piezoelectric ceramic actuator 3 The low-voltage end of the piezoelectric ceramic actuator 3 is connected to the sampling threshold processing circuit 4 for sampling the working current of the piezoelectric ceramic actuator 3, and the sampling threshold processing circuit 4 is connected to the current control circuit 7, and the current control circuit 7 is respectively passed through the logic driving circuit. Connected to the gate terminal of the high-voltage charging switch tube T1 and the gate terminal of the discharge switch tube T2;

The first processor 1 is connected with the current control circuit 7, and can input the high-frequency capture enabling signal to the current control circuit 7; When matching, the sampling threshold processing circuit 4 outputs a threshold current control trigger signal to the current control circuit 7, and the current control circuit 7 can effectively capture the threshold current control trigger signal output by the sampling threshold circuit 4 through the high-frequency capture enable signal, and the current control circuit 7 Control the trigger signal to output the current control signal according to the captured threshold current, and the logic drive circuit adjusts the corresponding switching states of the high-voltage charging switch tube T1 and the discharge switch tube T2 according to the current control signal, so that the working current of the piezoelectric ceramic actuator 3 is consistent with the preset match the current threshold.

Specifically, the piezoelectric ceramic actuator 3 is the actuator of the piezoelectric ceramic injector in the common rail system, the source terminal of the high-voltage charging switch tube T1 is connected to the high-voltage source VCC_BOOST, and the high-voltage charging switch tube T1 and the discharge switch tube T2 are both used MOS tube. When the high-voltage charging switch tube T1 is turned on, the high-voltage source VCC_BOOST can charge the piezoelectric ceramic actuator 3, and when the discharge switch tube T2 is turned on, it can discharge the piezoelectric ceramic actuator 3. In the piezoelectric ceramic actuator In a cycle of 3, the high-voltage charge switch T1 and the discharge switch T2 will not be turned on at the same time, and the conduction time interval between the high-voltage charge switch T1 and the discharge switch T2 is the fuel injection pulse width. The first processor 1 adopts commonly used micro-processing chips or integrated circuits, such as single-chip microcomputers, etc., and the first processor 1 can realize the switching state of the high-voltage charging switch tube T1 and the discharge switch tube T2 through the logic drive circuit and the current control circuit 7 control and regulation.

In the embodiment of the present invention, the operating current of the piezoelectric ceramic actuator 3 includes a charging operating current and a discharging operating current. The mismatch between the operating current on the piezoelectric ceramic actuator 3 and the preset current threshold in the sampling threshold processing circuit 4 means that the The operating current of the piezoelectric ceramic actuator 3 is greater than the preset current threshold, that is, the charging operating current or the discharging operating current is greater than the preset current threshold. At this time, the sampling threshold circuit 4 can output a threshold current control trigger signal to the current control circuit 7; , the preset current threshold in the sampling threshold processing circuit 4 can be set according to the work selection of different piezoelectric ceramic actuators 3 , the specific process and setting are well known to those skilled in the art, and will not be repeated here. The first processor 1 has been outputting the high-frequency capture enable signal to the current control circuit 7, and the current control circuit 7 can capture the threshold current control trigger signal under the action of the high-frequency capture enable signal, and control the trigger signal according to the threshold current Output current control signal.

The logic driving circuit adjusts the corresponding switching states of the high-voltage charging switch tube T1 and the discharging switch tube T2 according to the current control signal. When the charging working current on the device 3 is greater than the preset current threshold, the logic drive circuit turns off the high-voltage charging switch tube T1; when the discharge switch tube T2 is turned on, the piezoelectric ceramic actuator 3 is in the discharge phase, and the piezoelectric ceramic actuator 3 When the discharge working current of the piezoelectric ceramic actuator 3 is greater than the preset current threshold, the logic drive circuit turns off the discharge switch tube T2, so that the charging working current and the discharging working current of the piezoelectric ceramic actuator 3 match the preset current threshold, realizing the control of the piezoelectric ceramic actuator 3 Precise control of working current. In addition, in the embodiment of the present invention, the charging working current, the discharging working current match the preset current threshold, or the difference between the charging working current, the discharging working current and the preset current threshold is within an allowable error range, The details are well known to those skilled in the art, and details are not repeated here.

Further, the first processor 1 is connected to the sampling threshold processing circuit 4, and the first processor 1 can transmit a current adjustment control signal to the sampling threshold processing circuit 4, so as to adjust the sampling threshold processing circuit 4 through the current adjustment control signal. within the preset current threshold.

In the practical application of diesel engine piezoelectric ceramic injectors, the sampling threshold processing circuit 4 needs to set different preset current thresholds in different stages. In order to be able to different preset current thresholds, in the embodiment of the present invention, the first processor 1 The sampling threshold processing circuit 4 is connected, and the sampling threshold processing circuit 4 can adjust the preset current threshold according to the current adjustment control signal, so as to adapt to the working current control of the piezoelectric ceramic actuator 3 in different stages.

The sampling threshold processing circuit 4 includes a current sampling circuit 5 for sampling the operating current of the piezoelectric ceramic actuator 3 and a threshold control circuit 6 for comparing the operating current sampled by the current sampling circuit 5; threshold control The circuit 6 has a preset current threshold. When the sampled operating current does not match the preset current threshold, the threshold control circuit 6 outputs a threshold current control trigger signal to the current control circuit 7 .

As shown in Figure 4, the sampling threshold processing circuit 4 includes an amplifier U6, the non-inverting end of the amplifier U6 is connected to one end of the resistor R2, the inverting end of the amplifier U6 is connected to one end of the resistor R3 and one end of the resistor R4, and the resistor The other end of R3 is grounded, the other end of resistor R4 is connected to the output end of amplifier U6 and one end of resistor R5, resistor R5 is connected to one end of resistor R11 through resistor R10, the other end of resistor R11 is connected to one end of capacitor C1, comparator U7 The inverting end of the capacitor C1 is connected to one end of the resistor R12, the other end of the capacitor C1 is connected to the non-inverting end of the comparator U7, one end of the resistor R9 and one end of the resistor R8, the other end of the resistor R9 is connected to the DA module 11, and the other end of the resistor R8 One end is connected to the collector terminal of the transistor Q2, the emitter terminal of the transistor Q2 is grounded, the base terminal of the transistor Q2 is connected to one end of the resistor R6 and one end of the resistor R7, and the other end of the resistor R7 is grounded; the other end of the resistor R12 is connected to the comparator U7 The output end of the resistor R13 is connected with one end of the resistor R14, and the other end of the resistor R13 is connected with +3.3V voltage.

Specifically, the amplifier U6, the resistor R2, the resistor R3, the resistor R4 and R5 form the current sampling circuit 5, the DA module 11 and the transistor Q2 form the adjustment part of the preset current threshold, and the part of the comparator U7 is used to obtain the current sampling circuit 5. The operating current is compared with the preset current threshold. When the operating current is greater than the preset current threshold, the comparator U7 outputs a threshold current control trigger signal through the resistor R14, which is I_control1. Since the current sampling circuit 5 is connected to the inverting terminal of the comparator U7, the threshold current control trigger signal is a low level signal.

One end of the resistor R2 is connected to the non-inverting end of the amplifier U6, the other end of the resistor R2 is connected to the low-voltage end of the piezoelectric ceramic actuator 3 and the sampling resistor R1, the positive power supply terminal of the amplifier U6 is connected to 5V voltage, and the negative power supply terminal of the amplifier U6 is grounded . The positive power supply end of the comparator U7 is connected to the +5V voltage, and the positive power supply end of the comparator U7 is grounded through the capacitor C2, one end of the resistor R14 is connected to the output end of the comparator U7, and the other end of the resistor R14 is connected to the current control circuit 7 . The DA module 11 is connected to the output terminal of the first processor 1 , the base terminal of the transistor Q2 is connected to one end of the resistor R6 , and the other end of the resistor R6 is also connected to the output terminal of the first processor 1 . The DA module 11 receives the current regulation control signal output by the first processor 1, and the DA module 11 can output a voltage of 0~5V according to the current regulation control signal, and the voltage is loaded on the non-inverting terminal of the comparator U7 through the resistor R9. After the other end of the resistor R6 is connected to the first processor 1, the current conversion signal output by the first processor 1 is PEAK_EN1 to drive the transistor Q2. When the driver of the transistor Q2 is turned on, it can communicate with the DA module 11 In cooperation, the comparator at the non-inverting end of the comparator U7 is increased, that is, the preset current threshold in the threshold control circuit 6 can be quickly and effectively adjusted.

Further, in order to be able to adjust the change curve of the operating current of the piezoelectric ceramic actuator 3, the high voltage end of the piezoelectric ceramic actuator 3 is connected to the source terminal of the high voltage charging switch tube T1 through the inductance gating circuit 2 and to the discharge switch The drain end of the tube T2 is connected, the low-voltage end of the piezoelectric ceramic actuator 3 is grounded through the sampling resistor R1, and the sampling threshold value processing circuit 4 is connected with the sampling resistor R1 to collect the working current of the piezoelectric ceramic actuator 3 through the sampling resistor R1; A processor 1 can input an inductance gating signal to the inductance gating circuit 2, and the inductance gating circuit 2 can adjust the inductance value connected to the piezoelectric ceramic actuator 3 according to the inductance gating signal.

As shown in Figure 2, the inductance gating circuit 2 includes an inductance L1 and an inductance L2, one end of the inductance L1 is connected to the anode end of the diode D1, the cathode end of the diode D2, the drain end of the switching tube Q1, and the high voltage charging switch tube T1. The source terminal and the drain terminal of the discharge switch tube T2 are connected, the other end of the inductor L1 is connected to the anode terminal of the diode D3 and the cathode terminal of the diode D4, the anode terminal of the diode D2 and the anode terminal of the diode D4 are both grounded, and the cathode terminal of the diode D1 , the cathode end of the diode D1, and the cathode end of the diode D3 are all connected to the high voltage source VCC_BOOST; Inductance strobe signal; one end of the inductor L2 is connected to the source terminal of the switch tube Q1 and the cathode terminal of the diode D5, the other end of the inductor L2 is connected to the anode terminal of the diode D6, the anode terminal of the diode D5 is grounded, and the cathode terminal of the diode D6 is connected to the High voltage source VCC_BOOST connection.

In the embodiment of the present invention, the bootstrap circuit 10 can receive the inductance gate signal, and the switch tube Q1 can be driven by the bootstrap circuit 10 . When the high-voltage charging switch tube T1 is turned on, since the source end of the high-voltage charging switch tube T1 is connected to one end of the inductance L1, the other end of the inductance L2 is connected to the anode end of the diode D6 and the high-voltage end of the piezoelectric ceramic actuator 3 is connected. Therefore, the high-voltage source VCC_BOOST can charge the high-voltage end of the piezoelectric ceramic actuator 3 through the source terminal of the high-voltage charging switch T1 and the inductor L1 . When it is necessary to adjust the inductance value connected to the piezoelectric ceramic actuator 3, the first processor 1 drives the switch tube Q1 to be turned on through the inductance gating signal and the bootstrap circuit 10. After the switch tube Q1 is turned on, the inductor L1 and the inductor L2 Parallel connection is realized, thereby adjusting the inductance value connected to the piezoelectric ceramic actuator 3 . Diodes D1 to D6 can achieve effective protection.

The current control circuit 7 includes a second processor 8 and a latch 9, the second processor 8 and the latch 9 both receive the threshold current control trigger signal output by the sampling threshold processing circuit 4, and the second processor 8 simultaneously receive the high-frequency capture enable signal output by the first processor 1; under the action of the high-frequency capture enable signal, when the second processor 8 simultaneously receives the threshold current control trigger signal, the second processor 8 can send The latch 9 outputs the working current control trigger signal, and the latch 9 outputs the current control signal according to the working current control trigger signal and the threshold current control trigger signal, so that the logic driving circuit can adjust the high-voltage charging switch tube T1 and the discharge switch according to the current control signal Switch state of tube T2.

As shown in Figure 3, described second processor 8 comprises CPLD processor U4 and inverter U3, and described inverter U3 is connected with the output end of sampling threshold control circuit 4, and the output end of inverter U3 is connected with CPLD The input terminal of the processor U4 is connected, and the CPLD processor U4 also receives the high-frequency capture enable signal output by the first processor 1 , and the CPLD processor U4 can output an operating current control trigger signal to the latch 9 .

Specifically, the second processor 8 adopts a CPLD, and the high-frequency capture enable signal can be effectively captured by the CPLD processor U4. At the same time, the threshold current control trigger signal output by the sampling threshold processing circuit 4 can be controlled by the CPLD processor U4. to capture. The input terminal of the inverter U3 is used to receive the threshold current control trigger signal. After the inverter U3 is reversed, a high level can be obtained in the CPLD processor U4. At this time, the CPLD (Complex Programmable Logic Device) processor U4 A working current control trigger signal can be input to the latch 9 , and the working current control trigger signal is connected to the SCK terminal of the latch 9 as a clock signal of the latch 9 . The power supply terminal of the latch 9 is connected to the +5V voltage, and the input terminal of the latch 9 is connected to the threshold current control trigger signal. When the working current control trigger signal is valid, the latch 9 can latch the threshold current control trigger signal Output, which can output current control signal. During the latching time of the latch 9, the current control signal is valid. When the current control signal is valid, the high-voltage charging switch tube T1 or the discharge switch tube T2 can be turned off through the logic drive circuit, realizing the implementation of piezoelectric ceramics. The control of the charging current and discharging current of the device 3 and the latching time of the latch 9 can be set as required, and the latching time of the latch 9 is well known to those skilled in the art, and will not be repeated here. In the embodiment of the present invention, the threshold current control trigger signal is captured by the CPLD processor U4, and the latch 9 latches the threshold current control trigger signal, and within the latch time of the latch 9, the current control signal can be kept Invariant and effective, the control accuracy of the working current of the piezoelectric ceramic actuator 3 can be improved, and the power consumption of current modulation and system resource overhead can be reduced.

The logic driving circuit includes a first AND gate U1 and a second AND gate U2, an input end of the first AND gate U1 and an input end of the second AND gate U2 are connected to the output end of the current control circuit 7, and the first AND gate U1 is connected to the output end of the current control circuit 7. The other input end of the AND gate U1 is connected to the output end of the first processor 1 to receive the high-voltage switch charging signal output by the first processor 1; the other input end of the second AND gate U2 is connected to the output end of the first processor 1. The output terminal is connected to receive the discharge tube work trigger signal output by the first processor 1; the output terminal of the first AND gate U1 is connected to the gate terminal of the high-voltage charging switch tube T1, and the output terminal of the second AND gate U2 is connected to the discharge switch tube The gate terminal connection of T2;

The first AND gate U1 can drive and open the high-voltage charging switch tube T1 according to the high-voltage switch charging signal output by the first processor 1, and can turn off the high-voltage charging switch tube T1 according to the current control signal output by the current control circuit 7; the second AND gate U2 can drive and turn on the discharge switch tube T2 according to the discharge tube working trigger signal output by the first processor 1 , and can turn off the discharge switch tube T2 according to the current control signal output by the current control circuit 7 .

In the embodiment of the present invention, the input terminal of the first AND gate U1 can respectively receive the high-voltage switch charging signal output by the first processor 1 and the current control signal output by the latch 9, when the high-voltage switch charging signal is active at high level , the output terminal of the first AND gate U1 can drive and turn on the high-voltage charging switch tube T1; and when the current control signal output by the latch 9 is valid, the output terminal of the first AND gate U1 can turn off the high-voltage charging switch tube T1. In the second AND gate U2, when the discharge tube trigger signal received by the second AND gate U2 is valid, the output terminal of the second AND gate U2 can drive and turn on the discharge switch tube T2. At this time, the piezoelectric ceramic actuator 3 can pass The discharge switch tube T2 is in a discharge phase. When the piezoelectric ceramic actuator 3 is in the discharge phase and the current control signal output by the latch 9 is valid, the second AND gate U2 can turn off the discharge switch tube T2 to prevent the discharge current on the piezoelectric ceramic actuator 3 from exceeding the preset current threshold.

Further, the output terminal of the current control circuit 7 is connected to the first processor 1 to output the current control signal to the first processor 1; the first processor 1 can count the current control signal, when the first processor When the count value of 1 reaches the preset value, the first processor 1 can simultaneously turn off the high-voltage charging switch T1 and the discharge switch T2 through the logic driving circuit.

In the embodiment of the present invention, the preset value in the first processor 1 can be selected and set according to needs, and the output terminal of the latch 9 in the current control circuit 7 is connected to the input terminal of the first processor 1 at the same time, when the lock When the current control signal output by the register 9 is valid, the first processor 1 counts. When the count value reaches the preset value, the first processor 1 simultaneously turns off the high-voltage charging through the first AND gate U1 and the second AND gate U2. The switch tube T1 and the discharge switch tube T2 protect the piezoelectric ceramic actuator 3 .

The piezoelectric ceramic actuator 3 of the present invention is connected to the inductance gating circuit 2, and the inductance gating circuit 2 adjusts the inductance value connected to the piezoelectric ceramic actuator 3 through the inductance gating signal, thereby changing the piezoelectric ceramic actuator 3 The current conversion during work realizes different current response times; the threshold control circuit 6 can compare the working current of the piezoelectric ceramic actuator 3 with the preset current threshold, and can output a threshold current control trigger signal, and the first processor 1 The preset current threshold in the threshold control circuit 6 can be adjusted, so that the piezoelectric ceramic actuator 3 can have different peak currents, so that the driving process is a gradual process. The second processor 8 adopts the CPLD processor U4, and the CPLD processor U4 captures the threshold current control trigger signal under the action of the high-frequency capture enable signal. The latch 9 latches the threshold current control trigger signal according to the working current control trigger signal and outputs the current control signal. The logic driving circuit adopts two The AND gate, through the current control signal, realizes the switching state control of the high-voltage charging switch tube T1 and the discharge switch tube T2, which can realize precise control of the driving current, ensure the consistency of the driving current, reduce switching losses, and improve the efficiency of the electric control system. reliability.

Claims (10)

1. a driving current control circuit for diesel engine piezoelectric constant oil spout device, comprises first processor (1) and piezoelectric ceramic actuator (3); It is characterized in that: the high voltage terminal of described piezoelectric ceramic actuator (3) is connected with the source terminal of high-voltage charging switch transistor T 1 and is connected with the drain electrode end of discharge switch pipe T2, the source terminal ground connection of discharge switch pipe T2; The low voltage terminal of described piezoelectric ceramic actuator (3) is connected with the sampling threshold processing circuit (4) for sampling to the operating current of described piezoelectric ceramic actuator (3), described sampling threshold processing circuit (4) is connected with current control circuit (7), and current control circuit (7) is connected with the gate terminal of high-voltage charging switch transistor T 1, the gate terminal of discharge switch pipe T2 respectively by logic drive circuit;

First processor (1) is connected with current control circuit (7), and can to current control circuit (7) input radio frequency capture enable signal, when the operating current on piezoelectric ceramic actuator (3) does not mate with predetermined current threshold in sampling threshold processing circuit (4), sampling threshold processing circuit (4) exports threshold current to current control circuit (7) and controls trigger signal, current control circuit (7) effectively can be caught by radio frequency capture enable signal the threshold current that sampling threshold circuit (4) exports and be controlled trigger signal, current control circuit (7) controls trigger signal output current control signal according to the threshold current of catching, logic drive circuit regulates high-voltage charging switch transistor T 1 according to current controling signal, the corresponding on off state of discharge switch pipe T2, match with the operating current and predetermined current threshold that make piezoelectric ceramic actuator (3).

2. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 1, it is characterized in that: described first processor (1) is connected with sampling threshold processing circuit (4), first processor (1) can to sampling threshold processing circuit (4) transmission current regulable control signal, with by the predetermined current threshold in described current regulation control signal adjustment sampling threshold processing circuit (4).

3. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 1, it is characterized in that: the high voltage terminal of described piezoelectric ceramic actuator (3) is connected with the source terminal of high-voltage charging switch transistor T 1 by inductance gating circuit (2) and is connected with the drain electrode end of discharge switch pipe T2, the low voltage terminal of piezoelectric ceramic actuator (3) is by sampling resistor R1 ground connection, sampling threshold processing circuit (4) is connected with sampling resistor R1, to be gathered the operating current of piezoelectric ceramic actuator (3) by sampling resistor R1; First processor (1) can to inductance gating circuit (2) input inductance gating siganl, and inductance gating circuit (2) can regulate the inductance value be connected with described piezoelectric ceramic actuator (3) according to inductance gating siganl.

4. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 3, is characterized in that: described sampling threshold processing circuit (4) comprises the threshold value control circuit (6) that the current sampling circuit (5) for sampling to the operating current of piezoelectric ceramic actuator (3) and the operating current for sampling to current sampling circuit (5) compare process; Threshold value control circuit has predetermined current threshold in (6), and when the operating current of sampling does not mate with predetermined current threshold, threshold value control circuit (6) exports threshold current to current control circuit (7) and controls trigger signal.

5. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 1, it is characterized in that: described current control circuit (7) comprises the second processor (8) and latch (9), described second processor (8), latch (9) all receive the threshold current control trigger signal that sampling threshold processing circuit (4) exports, and the second processor (8) receives the radio frequency capture enable signal that first processor (1) exports simultaneously; Under the effect of radio frequency capture enable signal, when the second processor (8) receives threshold current control trigger signal simultaneously, second processor (8) can to latch (9) output services Current Control trigger signal, latch (9) controls trigger signal according to operating current and threshold current controls trigger signal output current control signal, regulates the on off state of high-voltage charging switch transistor T 1 and discharge switch pipe T2 to make logic drive circuit according to current controling signal.

6. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 1, it is characterized in that: described logic drive circuit comprises first and door U1 and second and door U2, first is all connected with the output terminal of current control circuit (7) with an input end of door U2 with an input end, second of door U1, first is connected with the output terminal of first processor (1) with another input end of door U1, to receive the high-voltage switch gear charging signals that first processor (1) exports; Second is connected with the output terminal of first processor (1) with another input end of door U2, to receive the electric discharge lamp work trigger signal that first processor (1) exports; First is connected with the gate terminal of high-voltage charging switch transistor T 1 with the output terminal of door U1, and second is connected with the gate terminal of discharge switch pipe T2 with the output terminal of door U2;

The first high-voltage switch gear charging signals that can export according to first processor (1) with door U1 drives opens high-voltage charging switch transistor T 1, and the current controling signal that can export according to current control circuit (7) shutoff high-voltage charging switch transistor T 1; The second electric discharge lamp work trigger signal that can export according to first processor (1) with door U2 drives opens discharge switch pipe T2, and the current controling signal that can export according to current control circuit (7) shutoff discharge switch pipe T2.

7. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 1, is characterized in that: the output terminal of described current control circuit (7) is connected with first processor (1), with to first processor (1) output current control signal; First processor (1) can count current controling signal, and when the count value of first processor (1) reaches pre-set count values, first processor (1) turns off high-voltage charging switch transistor T 1 and discharge switch pipe T2 by logic drive circuit simultaneously.

8. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 3, it is characterized in that: described inductance gating circuit (2) comprises inductance L 1 and inductance L 2, one end of inductance L 1 and the anode tap of diode D1, the cathode terminal of diode D2, the drain electrode end of switching tube Q1, the source terminal of high-voltage charging switch transistor T 1 and the drain electrode end of discharge switch pipe T2 connect, the other end of inductance L 1 is connected with the cathode terminal of the anode tap of diode D3 and diode D4, the anode tap of diode D2 and the equal ground connection of anode tap of diode D4, the cathode terminal of diode D1, the cathode terminal of diode D1, the cathode terminal of diode D3 is all connected with high-voltage power supply VCC_BOOST, the gate terminal of switching tube Q1 is connected with the output terminal of first processor (1) by bootstrap (10), to receive the inductance gating siganl that first processor (1) exports, one end of inductance L 2 is connected with the cathode terminal of the source terminal of switching tube Q1 and diode D5, and the other end of inductance L 2 is connected with the anode tap of diode D6, the anode tap ground connection of diode D5, and the cathode terminal of diode D6 is connected with high-voltage power supply VCC_BOOST.

9. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 5, it is characterized in that: described second processor (8) comprises CPLD processor U4 and phase inverter U3, described phase inverter U3 is connected with the output terminal of sampling threshold control circuit (4), the output terminal of phase inverter U3 is connected with the input end of CPLD processor U4, CPLD processor U4 also receives the radio frequency capture enable signal that first processor (1) exports, and CPLD processor U4 can to latch (9) output services Current Control trigger signal.

10. the driving current control circuit of diesel engine piezoelectric constant oil spout device according to claim 1, it is characterized in that: described sampling threshold processing circuit (4) comprises amplifier U6, the in-phase end of described amplifier U6 is connected with one end of resistance R2, the end of oppisite phase of amplifier U6 is connected with one end of one end of resistance R3 and resistance R4, the other end ground connection of resistance R3, the other end of resistance R4 is connected with one end of the output terminal of amplifier U6 and resistance R5, resistance R5 is connected with one end of resistance R11 by resistance R10, the other end of resistance R11 and one end of electric capacity C1, the end of oppisite phase of comparator U7 and one end of resistance R12 connect, the other end of electric capacity C1 and the in-phase end of comparator U7, one end of resistance R9 and one end of resistance R8 connect, the other end of resistance R9 is connected with D/A module (11), the other end of resistance R8 is connected with the collector terminal of triode Q2, the emitter terminal ground connection of triode Q2, the base terminal of triode Q2 is connected with one end of one end of resistance R6 and resistance R7, the other end ground connection of resistance R7, the other end of resistance R12 is connected with one end of the output terminal of comparator U7, resistance R13 and one end of resistance R14, and the other end of resistance R13 is connected with+3.3V voltage.