A driving circuit of an electrically-controlled common-rail fuel injector for a diesel engine

Abstract

This invention discloses a drive circuit for an electronically controlled common rail injector for a diesel engine, including a control unit and a boost unit. The control unit includes several operational amplifiers, several resistors, a digital potentiometer, and a capacitor. Among the several operational amplifiers, the non-inverting input of operational amplifier U2 is connected to one end of resistor R4 and one end of resistor R5, the inverting input is connected to one end of resistor R2 and one end of capacitor C2, and the output terminal is connected to the other end of resistor R5, the non-inverting input of operational amplifier U3, and the third pin of digital potentiometer U1. The inverting input of operational amplifier U3 is connected to the other end of resistor R4, one end of resistor R6, and one end of resistor R7. The non-inverting input of operational amplifier U4 is connected to the Vref terminal, the inverting input is connected to one end of resistor R8 and one end of resistor R9, and the output terminal is connected to one end of resistor R1 and the second pin of digital potentiometer U1. The fifth and sixth pins of digital potentiometer U1 are connected to the other end of resistor R2, and the seventh pin and one end of resistor R3 are connected to the Port_1 terminal.

Description

Technical Field

[0001] This invention relates to the field of fuel injector drive control technology, and in particular to a drive circuit for an electronically controlled common rail fuel injector for diesel engines. Background Technology

[0002] The common rail injector's drive circuit, as the core actuator of fuel control, mainly controls the action of the solenoid valve to achieve precise injection. Due to factors such as fluid resistance and sealing pressure, the solenoid valve requires a large drive current to overcome various resistances during initial startup. As the solenoid valve opens, the drive current can be reduced to maintain operation and reduce consumption.

[0003] CN104747332A discloses a drive circuit for an electronically controlled common rail injector for a diesel engine. It uses a high-voltage power supply of 48V to power the injection drive circuit, which satisfies the rapid response of the injector solenoid valve during the opening phase. After the injector is opened, a low-voltage power supply of 24V is used to power the injection drive circuit to maintain the open state of the injector. However, the problem is that the dual power supply control will have current discontinuity during switching and is prone to power conflict. In addition, there are few drive valves that can simultaneously meet the dual power supply voltage requirements. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a drive circuit for an electronically controlled common rail injector for diesel engines, comprising a control unit and a boost unit. The control unit includes several operational amplifiers (op-amps), several resistors, a digital potentiometer, and a capacitor. Among the several op-amps, the non-inverting input of op-amp U2 is connected to one end of resistor R4 and one end of resistor R5, the inverting input is connected to one end of resistor R2 and one end of capacitor C2, and the output is connected to the other end of resistor R5, the non-inverting input of op-amp U3, and the third pin of digital potentiometer U1. The inverting input of op-amp U3 is connected to the other end of resistor R4, one end of resistor R6, and one end of resistor R... 7. Connect the non-inverting input of op-amp U4 to Vref, the inverting input to one end of resistor R8 and one end of resistor R9, and the output to one end of resistor R1 and the second pin of digital potentiometer U1. Connect the fifth and sixth pins of digital potentiometer U1 to the other end of resistor R2. Connect the seventh pin and one end of resistor R3 to Port_1. Connect the eighth pin of digital potentiometer U1 and the other end of resistor R7 to the power supply. Connect the other ends of resistor R1, resistor R3, resistor R6, resistor R9, the fourth pin of digital potentiometer U1, and the other end of capacitor C2 to ground.

[0005] Furthermore, the boost unit includes a diode, a transistor, a capacitor, a resistor, and an inductor. The anode of the diode D1 is connected to one end of the inductor L1 and the collector of the transistor Q1, and the cathode is connected to one end of the capacitor C1, one end of the resistor RL, and the other end of the resistor R8. The base of the transistor Q1 is connected to the output terminal of the operational amplifier U3. The other end of the inductor L1 is connected to the DC terminal. The emitter of the transistor Q1, the other end of the capacitor C1, and the other end of the resistor RL are grounded.

[0006] Furthermore, the control unit also includes several field-effect transistors (FETs), several thyristors, several resistors, and an AND gate. The source of FET Q4 and the drain of FET Q5 are connected to a power supply. The drain of FET Q4 is connected to the control electrode of thyristor Q2 and one end of resistor R11, while its gate is connected to the gate of FET Q5, one end of resistor R16, and one end of resistor R1. The source of FET Q5 is connected to the control electrode of thyristor Q3 and one end of resistor R14. The anodes of thyristors Q2 and Q3 are connected to Port_2. The cathode of thyristor Q3 is connected to the first input terminal of AND gate U5 and one end of resistor R13. The cathode of thyristor Q2 is connected to the second input terminal of AND gate U5 and one end of resistor R12. The output terminal of AND gate U5 is connected to Port_1. The other ends of resistors R11, R12, R13, R14, and R16 are grounded.

[0007] Furthermore, the control unit also includes several resistors, one end of resistor R15 is connected to the power supply, and the other end of resistor R10 is connected to the Vref terminal; the other end of resistor R10 is grounded.

[0008] Furthermore, the control unit also includes a trigger, a diode, a transistor, and a resistor. The first pin of the trigger U6 is connected to one end of the resistor R1, the second pin is connected to the sixth pin, the third pin and the cathode of the diode D2 are connected to the anode of the thyristor Q3, and the fifth pin is connected to the base of the transistor Q6. The collector of the transistor Q6 is connected to one end of the resistor R21, and the emitter is connected to the Port_2 terminal. The other end of the resistor R21 is connected to the power supply. The anode of the diode D2 is connected to one end of the resistor R3 via the Port_1 terminal.

[0009] Furthermore, the control unit also includes several resistors, one end of resistor R19 and one end of resistor R20 are connected to the power supply; the other end of resistor R19 is connected to one end of resistor R18 and the drain of field-effect transistor Q5; the other end of resistor R20 is connected to one end of resistor R17 and the source of field-effect transistor Q4; and the other ends of resistor R17 and resistor R18 are grounded.

[0010] Furthermore, resistors R10 and R15 are adjustable resistors.

[0011] The advantages of this invention compared to the prior art are:

[0012] This invention allows for seamless control of the switching between starting current and freewheeling current via a single power supply, preventing intermittent current flow and power supply conflicts. Furthermore, the control can be activated only during the switching process, resulting in a more stable freewheeling flow and less circuit fluctuation. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A schematic diagram of the circuit structure provided by the present invention. Detailed Implementation

[0015] To make the objectives and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection specifically claimed by the present invention.

[0016] This invention discloses a drive circuit for an electronically controlled common rail injector for a diesel engine, including a control unit and a boost unit. The control unit includes several operational amplifiers, several resistors, a digital potentiometer, and a capacitor. Operational amplifier U2 has its non-inverting input connected to one end of resistor R4 and one end of resistor R5, its inverting input connected to one end of resistor R2 and one end of capacitor C2, and its output connected to the other end of resistor R5, the non-inverting input of operational amplifier U3, and the third pin of digital potentiometer U1. The inverting input of operational amplifier U3 is connected to the other end of resistor R4, one end of resistor R6, and one end of resistor R7. The non-inverting input of U4 is connected to the Vref input, the inverting input is connected to one end of resistor R8 and one end of resistor R9, and the output is connected to one end of resistor R1 and the second pin of digital potentiometer U1. The fifth and sixth pins of digital potentiometer U1 are connected to the other end of resistor R2, and the seventh pin and one end of resistor R3 are connected to the Port_1 input. The eighth pin of digital potentiometer U1 and the other end of resistor R7 are connected to the power supply. The other ends of resistor R1, resistor R3, resistor R6, resistor R9, the fourth pin of digital potentiometer U1, and the other end of capacitor C2 are grounded.

[0017] Specifically, the boost unit includes a diode, a transistor, a capacitor, a resistor, and an inductor. The anode of the diode D1 is connected to one end of the inductor L1 and the collector of the transistor Q1, and the cathode is connected to one end of the capacitor C1, one end of the resistor RL, and the other end of the resistor R8. The base of the transistor Q1 is connected to the output terminal of the operational amplifier U3. The other end of the inductor L1 is connected to the DC terminal. The emitter of the transistor Q1, the other end of the capacitor C1, and the other end of the resistor RL are grounded.

[0018] Specifically, the control unit further includes several field-effect transistors (FETs), several thyristors, several resistors, and an AND gate. The source of FET Q4 and the drain of FET Q5 are connected to a power supply. The drain of FET Q4 is connected to the control electrode of thyristor Q2 and one end of resistor R11, while its gate is connected to the gate of FET Q5, one end of resistor R16, and one end of resistor R1. The source of FET Q5 is connected to the control electrode of thyristor Q3 and one end of resistor R14. The anodes of thyristors Q2 and Q3 are connected to Port_2. The cathode of thyristor Q3 is connected to the first input terminal of AND gate U5 and one end of resistor R13. The cathode of thyristor Q2 is connected to the second input terminal of AND gate U5 and one end of resistor R12. The output terminal of AND gate U5 is connected to Port_1. The other ends of resistors R11, R12, R13, R14, and R16 are grounded.

[0019] Specifically, the control unit also includes several resistors, one end of resistor R15 is connected to the power supply, and the other end of resistor R10 is connected to the Vref terminal; the other end of resistor R10 is grounded.

[0020] Specifically, the control unit also includes a trigger, a diode, a transistor, and a resistor. The first pin of the trigger U6 is connected to one end of the resistor R1, the second pin is connected to the sixth pin, the third pin and the cathode of the diode D2 are connected to the anode of the thyristor Q3, and the fifth pin is connected to the base of the transistor Q6. The collector of the transistor Q6 is connected to one end of the resistor R21, and the emitter is connected to the Port_2 terminal. The other end of the resistor R21 is connected to the power supply. The anode of the diode D2 is connected to one end of the resistor R3 via the Port_1 terminal.

[0021] Specifically, the control unit further includes several resistors, one end of resistor R19 and one end of resistor R20 of the several resistors are connected to the power supply; the other end of resistor R19 is connected to one end of resistor R18 and the drain of field-effect transistor Q5; the other end of resistor R20 is connected to one end of resistor R17 and the source of field-effect transistor Q4; and the other ends of resistor R17 and resistor R18 are grounded.

[0022] Specifically, resistors R10 and R15 are adjustable resistors.

[0023] In one embodiment, a scheme for seamless conversion between single-power-supply start-up current and freewheeling current is provided. In this scheme, the DC input power supply is used, resistor RL is a load current-adjustable resistor, the Vref input is a valve drive voltage reference signal, resistors R8 and R9 are sampling resistors, transistor Q1, inductor L1, diode D1, and capacitor C1 form a boost unit, the inverting input of operational amplifier U4 is used to sample the output voltage of the boost unit, and the non-inverting input of operational amplifier U4 is the reference signal for the required drive voltage of the solenoid valve, with a coefficient ratio of Vref * resistor R9 / resistor R8. After comparing the non-inverting and inverting inputs, the output signal of operational amplifier U4 is pulled down by resistor R1 and fed back to pin 2 of digital potentiometer U1. Simultaneously, pin 7 of digital potentiometer U1 is connected via resistor R3. When digital potentiometer U1 is activated, in the initial state, the power signal at resistor R7 is divided by resistor R6 and input to resistor R4. The signal input to resistor R4 is then input to the non-inverting input of operational amplifier U2. When capacitor C2 is powered on and at a low potential, the voltage at the non-inverting input of operational amplifier U2 is greater than that at the inverting input. The output signal of operational amplifier U2 is input to capacitor C2 via pin 3 and pin 6 of digital potentiometer U1, and resistor R2. Resistor R2 is a protection resistor, used to ensure that operational amplifier U2 can output normally when the impedance of digital potentiometer U1 is low. As the voltage at capacitor C2 rises above the non-inverting input of operational amplifier U2, operational amplifier U2 is cut off. The signal at capacitor C2 is then looped through resistor R2, pin 6 and pin 3 of digital potentiometer U1, and the output of operational amplifier U2. Simultaneously, resistors R5 and... When the voltage drop at the connection terminal of op-amp U2 is at a low potential, the other end of the signal input to resistor R4 is fed back to the output terminal of op-amp U2 via resistor R5 to form a loop. The voltage drop across resistors R4 and R5 is such that when the potential of capacitor C2 is pulled down to the voltage across the connection terminal of resistors R4 and R5, op-amp U2 outputs again, making the output frequency of op-amp U2 correspond to the resistance value of digital potentiometer U1. The output signal of op-amp U2 is then fed back to the non-inverting input of op-amp U3. Because the output voltage of op-amp U2 is close to the power supply voltage and remains constant, resistors R7 and R6 also provide reference signals for the inverting input of op-amp U3. Op-amp U3 converts the analog signal output by op-amp U2 into a digital signal and feeds it back to transistor Q1. The boost unit boosts the voltage, and op-amp U4 detects this and feeds it back to pin 2 of digital potentiometer U1. When the resistor... When the resistor RL changes from starting current to freewheeling current, or vice versa, the resistance of RL increases or decreases. The voltage across capacitor C1 increases or decreases and, after passing through resistors R8 and R9, is input to operational amplifier U4 for comparison with Vref. Operational amplifier U4 outputs a signal to pin 2 of digital potentiometer U1. Digital potentiometer U1 adjusts its resistance from high to low or low to high based on the output state of operational amplifier U4. As the resistor vernier of digital potentiometer U1 changes, the input and output circuits of operational amplifier U2, digital potentiometer U1, resistor R2, and capacitor C2 change, causing the frequency of operational amplifier U2 to decrease or increase. This frequency is then output by operational amplifier U3 to the boost unit. When the voltage across capacitor C1 changes with the resistor RL from freewheeling current to starting current, the voltage across capacitor C1 is again mapped to Vref.Achieve seamless switching between single-supply startup current and freewheeling current.

[0024] In one embodiment, considering that the freewheeling current will fluctuate during real-time control, a conversion scheme with detection function is proposed based on the above scheme. This scheme can initiate control when switching between starting current and freewheeling current, resulting in a more stable freewheeling process and less circuit fluctuation. During detection, since there are two states—freewheeling to starting and starting to freewheeling—for unified detection and control, in this embodiment, pin 7 of the digital potentiometer U1 is connected to Port_1. The output of the operational amplifier U4, in addition to being fed back to pin 2 of the digital potentiometer U1, is also input to the gates of the field-effect transistors Q5 and Q4. When the resistor RL is adjusted, a signal is input to Port_2. The voltage at the capacitor C1 is input to the inverting input of the operational amplifier U4 after passing through resistors R8 and R9. Assuming... When the starting current switches to freewheeling mode, the resistance of resistor RL is increased. Operational amplifier U4 outputs a low-potential signal to the gates of MOSFETs Q4 and Q5, turning on MOSFET Q4 and turning off Q5. The power supply signal from resistor R20, after passing through the source of MOSFET Q4, is pulled up through two paths: one through the drain of MOSFET Q4, resistor R11, and ground; the other through the control electrode of thyristor Q2, the cathode of thyristor Q2, resistor R12, and ground, turning on thyristor Q2. The Port_2 signal, after being pulled up through the anode and cathode of thyristor Q2, resistor R12, and then fed back to the input of AND gate U5. Following the adjustment of the voltage across capacitor C1 by operational amplifier U3 to correspond with the coefficient of Vref, operational amplifier U4 outputs a high-potential signal to the gates of MOSFETs Q4 and Q5. With the gate of MOSFET Q5 closed, MOSFET Q4 is off, and MOSFET Q5 is on. The current from the anode to the cathode of thyristor Q2 is not zero and is higher than the holding current, so thyristor Q2 is on. The power signal at resistor R19 passes through the drain of MOSFET Q5. One path is pulled up through the source of MOSFET Q5, resistor R14, and ground, while the other path is pulled up through the control electrode of thyristor Q3, the cathode of thyristor Q3, resistor R13, and ground, so thyristor Q3 is on. The Port_2 signal is pulled up through the anode and cathode of thyristor Q3, resistor R13, and then fed back to the other input of AND gate U5. The output signal of AND gate U5 is fed back to pin 7 of digital potentiometer U1 via Port_1. Digital potentiometer U1 is off, and the output frequency of op-amp U3 remains unchanged. Assuming the current transitions from freewheeling to starting current, the resistance of resistor RL is reduced. Operational amplifier U4 outputs a high-potential signal to the gates of MOSFETs Q4 and Q5. This signal is first output by thyristor Q3 to one input of AND gate U5, followed by output from thyristor Q2. After the voltage across capacitor C1 adjusts to match the coefficient of Vref, operational amplifier U4 outputs a low-potential signal to the gates of MOSFETs Q4 and Q5. MOSFET Q4 turns on, and MOSFET Q5 turns off. The power supply signal from resistor R20, after passing through the source of MOSFET Q4, is pulled up through the drain of MOSFET Q4, resistor R11, and ground in one path, and through the control electrode of thyristor Q2, the cathode of thyristor Q2, resistor R12, and ground in another path, turning on thyristor Q2.The Port_2 signal, after being pulled up by the anode and cathode of thyristor Q2 and resistor R12, is fed back to the input of AND gate U5. Once signals are present at both inputs of AND gate U5, the output signal is sent to Port_1 to stop adjusting the digital potentiometer U1. The output frequency of operational amplifier U3 remains unchanged. Upon reset, the input to Port_2 is stopped.

[0025] In one embodiment, considering that the circuit operation cannot be satisfied when the drive current of the host chip is low, the Port_2 signal is connected to the flip-flop U6 in the digital device. The direct connection between Port_2 and thyristors Q2 and Q3 is removed. When the resistor RL is adjusted, a signal is input to pin 3 of the flip-flop U6. The flip-flop U6 outputs a signal to the base of transistor Q6. After transistor Q6 is turned on, the power supply is current-limited by resistor R21 and then input to the anodes of thyristors Q2 and Q3 through transistor Q6. When AND gate U5 outputs, the signal is fed back to the flip-flop U6 through diode D2. After pin 5 of the flip-flop U6 is turned off, it is reset. Vref parameter In addition to being provided by the host, the test signal can also be provided via a voltage divider using resistors R15 and R10. Depending on the range, resistor R15 is set as an adjustable resistor when the voltage is increased, and vice versa. Resistors R17 and R18 are used for voltage divider to supply power to MOSFETs Q4 and Q5, preventing the gate input of MOSFETs Q5 and Q4 from failing to achieve the positive and negative voltage difference. MOSFETs Q4 and Q5 can also be input via a power supply. The load current resistor RL can also be set as a start-up resistor and a freewheeling resistor as needed, and its connection is controlled by a switch (not shown in the attached diagram).

[0026] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A drive circuit for an electrically controlled common rail fuel injector of a diesel engine, characterized in that, The system includes a control unit and a boost unit. The control unit includes several operational amplifiers (op-amps), several resistors, a digital potentiometer, and a capacitor. Among the several op-amps, the non-inverting input of op-amp U2 is connected to one end of resistor R4 and one end of resistor R5, the inverting input is connected to one end of resistor R2 and one end of capacitor C2, and the output is connected to the other end of resistor R5, the non-inverting input of op-amp U3, and the third pin of digital potentiometer U1. The inverting input of op-amp U3 is connected to the other end of resistor R4, one end of resistor R6, and one end of resistor R7. The non-inverting input of op-amp U4 is connected to the Vref terminal. The inverting terminal is connected to one end of resistor R8 and one end of resistor R9; the output terminal is connected to one end of resistor R1 and the second pin of digital potentiometer U1; the fifth and sixth pins of digital potentiometer U1 are connected to the other end of resistor R2; the seventh pin and one end of resistor R3 are connected to the Port_1 terminal; the eighth pin of digital potentiometer U1 and the other end of resistor R7 are connected to the power supply; the other ends of resistor R1, resistor R3, resistor R6, resistor R9, the fourth pin of digital potentiometer U1, and the other end of capacitor C2 are grounded.

2. The drive circuit of an electrically controlled common rail injector for a diesel engine according to claim 1, characterized in that, The boost unit includes a diode, a transistor, a capacitor, a resistor, and an inductor. The anode of diode D1 is connected to one end of inductor L1 and the collector of transistor Q1, and the cathode is connected to one end of capacitor C1, one end of resistor RL, and the other end of resistor R8. The base of transistor Q1 is connected to the output terminal of operational amplifier U3. The other end of inductor L1 is connected to the DC terminal. The emitter of transistor Q1, the other end of capacitor C1, and the other end of resistor RL are grounded.

3. The drive circuit for the electronically controlled common rail injector of a diesel engine according to claim 1, characterized in that, The control unit further includes several field-effect transistors (FETs), several thyristors, several resistors, and an AND gate. The source of FET Q4 and the drain of FET Q5 are connected to a power supply. The drain of FET Q4 is connected to the control electrode of thyristor Q2 and one end of resistor R11, while its gate is connected to the gate of FET Q5, one end of resistor R16, and one end of resistor R1. The source of FET Q5 is connected to the control electrode of thyristor Q3 and one end of resistor R14. The anodes of thyristors Q2 and Q3 are connected to Port_2. The cathode of thyristor Q3 is connected to the first input terminal of AND gate U5 and one end of resistor R13. The cathode of thyristor Q2 is connected to the second input terminal of AND gate U5 and one end of resistor R12. The output terminal of AND gate U5 is connected to Port_1. The other ends of resistors R11, R12, R13, R14, and R16 are grounded.

4. The drive circuit for the electronically controlled common rail injector of a diesel engine according to claim 1, characterized in that, The control unit also includes several resistors, one end of resistor R15 is connected to the power supply and the other end of resistor R10 is connected to the Vref terminal; the other end of resistor R10 is grounded.

5. The drive circuit for the electronically controlled common rail injector of a diesel engine according to claim 3, characterized in that, The control unit also includes a trigger, a diode, a transistor, and a resistor. The first pin of the trigger U6 is connected to one end of the resistor R1, the second pin is connected to the sixth pin, the third pin and the cathode of the diode D2 are connected to the anode of the thyristor Q3, and the fifth pin is connected to the base of the transistor Q6. The collector of the transistor Q6 is connected to one end of the resistor R21, and the emitter is connected to the Port_2 terminal. The other end of the resistor R21 is connected to the power supply. The anode of the diode D2 is connected to one end of the resistor R3 via the Port_1 terminal.

6. The drive circuit for the electronically controlled common rail injector of a diesel engine according to claim 3, characterized in that, The control unit also includes several resistors, one end of resistor R19 and one end of resistor R20 are connected to the power supply; the other end of resistor R19 is connected to one end of resistor R18 and the drain of field-effect transistor Q5; the other end of resistor R20 is connected to one end of resistor R17 and the source of field-effect transistor Q4; and the other ends of resistor R17 and resistor R18 are grounded.

7. The drive circuit for the electronically controlled common rail injector of a diesel engine according to claim 4, characterized in that, The resistors R10 and R15 are adjustable resistors.

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