Fuel metering valve isolation drive and anti-interference protection circuit

Abstract

The application provides a fuel metering valve isolation driving and anti-interference protection circuit, comprising an input current limiting unit, an optoelectronic isolation unit, a switch driving unit and a signal sampling and feedback unit which are connected in series; wherein the input end of the input current limiting unit is electrically connected with a master control unit, the output end of the input current limiting unit is electrically connected with the input end of the optoelectronic isolation unit; the output end of the optoelectronic isolation unit is electrically connected with the input end of the switch driving unit, the output end of the switch driving unit is electrically connected with the signal sampling and feedback unit, and the signal sampling and feedback unit is respectively connected with a fuel metering valve and a filtering and shaping circuit and is electrically connected with the master control unit; the master control unit outputs a control signal as a circuit input instruction, the instruction is outputted after current limiting, isolation, switch driving and current sampling to output a driving signal to drive the fuel metering valve to act; the signal sampling and feedback unit converts a current feedback signal into a voltage signal and returns it to the master control unit by monitoring the current state in the circuit to perform state feedback on the fuel metering valve. The circuit has the characteristics of strong anti-interference, high reliability, fast response and adaptation to harsh vehicle working conditions, and can greatly improve the stability and service life of the high-pressure common rail fuel control system.

Description

Technical Field

[0001] This application belongs to the field of engine actuator control technology, and in particular relates to a fuel metering valve isolation drive and anti-interference protection circuit. Background Technology

[0002] The fuel metering valve is a core actuator in a high-pressure common rail engine. It is driven by control commands from the CPU (ECU main control chip) and requires real-time feedback of its operating status to the CPU to form a closed-loop control system, ensuring stable rail pressure, precise fuel injection, and self-diagnostic capabilities for faults. Existing traditional drive circuits have the following drawbacks: (1) The CPU low-voltage IO directly drives the 24V inductive load. Without isolation, it is prone to crosstalk and damages the main chip, resulting in extremely poor EMC. (2) The MOS gate has no voltage clamping, and the vehicle surge and coil back EMF can easily break down the MOS transistor, causing the drive to fail; (3) The drive output and status feedback signal are mixed and there is no independent link. The CPU cannot accurately check the circuit continuity and device failure. Summary of the Invention

[0003] In view of this, this application aims to provide a fuel metering valve isolation drive and anti-interference protection circuit to solve at least one of the above problems.

[0004] To achieve the above objectives, the technical solution of this application is implemented as follows: This application provides a fuel metering valve isolation drive and anti-interference protection circuit, including a cascaded input current limiting unit, an opto-isolation unit, a switch drive unit, and a signal sampling and feedback unit; The input terminal of the input current limiting unit is electrically connected to the main control unit, and the output terminal of the input current limiting unit is electrically connected to the input terminal of the opto-isolation unit. The output terminal of the opto-isolation unit is electrically connected to the input terminal of the switch driving unit, and the output terminal of the switch driving unit is electrically connected to the signal sampling and feedback unit. The signal sampling and feedback unit is respectively connected to the fuel metering valve and the filtered and shaped circuit and electrically connected to the main control unit. The main control unit outputs a control signal as a circuit input command. After the command is current-limited, isolated, switched, and sampled, a drive signal is output to drive the fuel metering valve to operate. The signal sampling and feedback unit monitors the current state in the circuit and converts the current feedback signal into a voltage signal, which is then sent back to the main control unit to perform status feedback on the fuel metering valve.

[0005] Furthermore, the opto-isolation unit includes an optocoupler, the input terminal of which is connected to the output terminal of the ECU main control chip through a current-limiting resistor, and the output terminal of which is electrically connected to the switch drive unit through a switch gate voltage regulation clamping protection unit composed of a first resistor, a second resistor, and a Zener diode.

[0006] Furthermore, the switch driving unit includes a switching transistor, the first end of which is electrically connected to the common connection terminal of the first resistor, the second resistor and the Zener diode, the second end of which is electrically connected to the signal sampling and feedback unit, and the third end of which is connected to the 24VP1 power supply side.

[0007] Furthermore, the switching transistor is a VSD045P10MS P-channel MOSFET.

[0008] Furthermore, the signal sampling and feedback unit includes a signal conditioning chip. The input terminal of the signal conditioning chip is connected to the switching transistor and the fuel metering valve, respectively. The output terminal of the signal conditioning chip is shaped by a filtering unit and outputs a current feedback signal to the ECU main control chip.

[0009] Furthermore, the filtering unit is composed of a third resistor, a first filtering capacitor, and a second filtering capacitor connected together. The common terminal of the third resistor and the first filtering capacitor is connected to the output terminal of the signal conditioning chip, and the common terminal of the third resistor and the second filtering capacitor is connected to the ECU main control chip.

[0010] Furthermore, the signal conditioning chip is a BS6023-5B model chip.

[0011] Compared with the prior art, the fuel metering valve isolation drive and anti-interference protection circuit described in this application has the following advantages: The fuel metering valve isolation drive and anti-interference protection circuit described in this application comprises a control signal output from the main control unit, which, after optocoupler isolation, gate clamping protection, and power switch drive, drives the fuel metering valve. Simultaneously, an output current feedback signal is sent back to the main control unit, integrating command issuance, load execution, and closed-loop self-testing. Precise gate clamping prevents surge breakdown of the switching transistor, optocoupler isolation protects the main control chip, and dual-channel signals independently achieve precise closed-loop control and fault diagnosis. The circuit structure of this application features strong anti-interference, high reliability, fast response, and adaptability to harsh vehicle operating conditions, significantly improving the stability and service life of the high-pressure common rail fuel control system. Attached Figure Description

[0012] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of a fuel metering valve isolation drive and anti-interference protection circuit according to an embodiment of this application. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0014] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0015] Please see Figure 1 As shown, this embodiment provides a fuel metering valve isolation drive and anti-interference protection circuit, including a cascaded input current limiting unit, an opto-isolation unit, a switch drive unit, and a signal sampling and feedback unit; The input terminal of the input current limiting unit is electrically connected to the main control unit, and the output terminal of the input current limiting unit is electrically connected to the input terminal of the opto-isolation unit. The output of the opto-isolation unit is electrically connected to the input of the switch drive unit, and the output of the switch drive unit is electrically connected to the signal sampling and feedback unit. The signal sampling and feedback unit is connected to the fuel metering valve and the filtered and shaped circuit is electrically connected to the main control unit, respectively. The main control unit outputs a control signal as a circuit input command. After the command is current-limited, isolated, driven by a switch, and sampled by current, a drive signal is output to drive the fuel metering valve to operate. The signal sampling and feedback unit monitors the current state in the circuit and converts the current feedback signal into a voltage signal, which is then sent back to the main control unit to provide status feedback for the fuel metering valve.

[0016] Specifically, in this embodiment, the CPU main control unit (using the ECU main control chip) outputs a control signal O_S_MEUNH as a circuit input command. After current limiting, isolation, and switching drive, the command outputs O_S_MEUNH_OUT, which connects to the fuel metering valve to achieve load drive. At the same time, the circuit outputs an independent status feedback signal O_S_MEUNH_ST back to the CPU main control unit, forming a closed-loop control and fault self-check, realizing the integration of command issuance, load execution, and closed-loop self-check. Among them, O_S_MEUNH_OUT is a high-power drive signal that directly drives the fuel metering valve coil; O_S_MEUNH_ST is a clean signal that is only used for CPU closed-loop status verification. The two signals are independent and do not interfere with each other, so the CPU fault diagnosis is accurate and can complete the real-time identification of circuit abnormalities and device failures.

[0017] In some embodiments, the opto-isolation unit includes an optocoupler U36. The input terminal of the optocoupler U36 is connected to the output terminal of the ECU main control chip through a current-limiting resistor R421. The output terminal of the optocoupler U36 is electrically connected to the switch drive unit through a switch gate voltage regulation clamping protection unit composed of a first resistor R419, a second resistor R415 and a Zener diode Z35. The switching drive unit includes a switching transistor Q17. The first terminal of the switching transistor Q17 is electrically connected to the common connection terminal of the first resistor R419, the second resistor R415 and the Zener diode Z35. The second terminal of the switching transistor Q17 is electrically connected to the signal sampling and feedback unit. The third terminal of the switching transistor Q17 is connected to the 24VP1 power supply side.

[0018] Specifically, in this embodiment, the CPU output O_S_MEUNH is connected to the primary pin 2 of optocoupler U36 (the opto-isolation unit samples the GH281 optocoupler to achieve complete electrical isolation between the CPU's low-voltage digital circuit and the 24V high-voltage circuit of the fuel metering valve) via the current-limiting resistor R421. Pin 1 of U36 is connected to the 5VD1 digital power supply, and a filter capacitor C283 is connected in parallel with GD1. Pin 3 of U36 is connected to the power ground GP1, and pin 4 is simultaneously connected to the gate of resistor R419 and the switching transistor Q17 (Q17 is a P-channel MOSFET of model VSD045P10MS) to achieve complete electrical isolation between the CPU's low voltage circuit and the 24V load's high voltage circuit.

[0019] Z35, R415, and R419 form a 15V gate voltage regulation clamping protection unit for the MOSFET. A filter capacitor C282 is connected in parallel to GP1 via the 24VP1 vehicle power supply. One end of resistor R415 is connected to 24VP1, and the other end is connected to the gate of Q17. The cathode of Z35 is connected to 24VP1, and the anode is connected to the gate of Q17, forcibly limiting the maximum gate voltage to 15V to prevent surges and reverse voltage from damaging the MOSFET. The source of Q17 is connected to 24VP1, and the drain is connected to pins 1 and 2 of the signal conditioning chip U35. After sampling, the signal conditioning chip U35 directly outputs O_S_MEUNH_OUT, which is connected to the external fuel metering valve coil to complete the load drive action.

[0020] In some embodiments, the signal sampling and feedback unit includes a signal conditioning chip U35. The input terminals of the signal conditioning chip U35 are connected to the switching transistor and the fuel metering valve, respectively. The output terminal of the signal conditioning chip U35 is shaped by a filtering unit and outputs a current feedback signal to the ECU main control chip. The filtering unit consists of a third resistor R417, a first filter capacitor C307, and a second filter capacitor C308 connected in series. The common terminal of the third resistor R417 and the first filter capacitor C307 is connected to the output terminal of the signal conditioning chip U35, and the common terminal of the third resistor R417 and the second filter capacitor C308 is connected to the ECU main control chip.

[0021] Specifically, in this embodiment, the signal conditioning chip U35 (U35 adopts the BS6023-5B model chip) samples the current and converts it into a voltage signal. After being filtered and shaped by R417, C307, and C308, the output of U35 outputs the O_S_MEUNH_ST status feedback signal, which is directly connected to the AN pin of the ECU main control chip. The CPU compares the output O_S_MEUNH with the feedback O_S_MEUNH_ST to determine the status of the drive circuit and realize closed-loop self-test.

[0022] The circuit works as follows: The CPU main control unit outputs a control signal O_S_MEUNH based on engine speed and rail pressure requirements. This signal, after current limiting and optocoupler isolation, controls Q17. When O_S_MEUNH is low, optocoupler U36 is on, and PMOS transistor Q17 is on. The current supplied by power supply 24VP1 flows through signal conditioning chip U35. O_S_MEUNH_OUT is connected to the fuel metering valve, forming a path, and the fuel pressure regulating valve is driven and controlled. When O_S_MEUNH is high, optocoupler U36 is off, PMOS transistor Q17 is off, and power supply 24VP1 cannot supply current to the fuel pressure regulating valve. Since the fuel pressure regulating valve is an inductive load, an induced current will be generated after power supply 24VP1 is turned off. Diode D49 provides a return path for this freewheeling current.

[0023] The signal conditioning chip U35 primarily monitors the current state in the circuit, converting the current feedback signal into a voltage signal O_S_MEUNH_ST, which is then sent to the CPU main control unit. The CPU main control unit provides feedback on the status of the fuel metering valve. The CPU main control unit performs high and low temperature and surge tests, and no components in the circuit are damaged or malfunctioning. The overall closed-loop control of the circuit is stable, and the rail voltage fluctuation is minimal.

[0024] The circuit structure of this application has the characteristics of strong anti-interference, high reliability, fast response, and adaptability to harsh vehicle operating conditions, which can significantly improve the stability and service life of the high-pressure common rail fuel control system.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0026] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A fuel metering valve isolation drive and anti-interference protection circuit, characterized in that: It includes cascaded input current limiting units, opto-isolation units, switch driving units, and signal sampling and feedback units; The input terminal of the input current limiting unit is electrically connected to the main control unit, and the output terminal of the input current limiting unit is electrically connected to the input terminal of the opto-isolation unit. The output terminal of the opto-isolation unit is electrically connected to the input terminal of the switch driving unit, and the output terminal of the switch driving unit is electrically connected to the signal sampling and feedback unit. The signal sampling and feedback unit is respectively connected to the fuel metering valve and the filtered and shaped circuit and electrically connected to the main control unit. The main control unit outputs a control signal as a circuit input command. After the command is current-limited, isolated, switched, and sampled, a drive signal is output to drive the fuel metering valve to operate. The signal sampling and feedback unit monitors the current state in the circuit and converts the current feedback signal into a voltage signal, which is then sent back to the main control unit to perform status feedback on the fuel metering valve.

2. The fuel metering valve isolation drive and anti-interference protection circuit according to claim 1, characterized in that: The opto-isolation unit includes an optocoupler. The input terminal of the optocoupler is connected to the output terminal of the ECU main control chip through a current-limiting resistor. The output terminal of the optocoupler is electrically connected to the switch drive unit through a switch gate voltage regulation clamping protection unit composed of a first resistor, a second resistor, and a Zener diode.

3. The fuel metering valve isolation drive and anti-interference protection circuit according to claim 2, characterized in that: The switch driving unit includes a switching transistor. The first end of the switching transistor is electrically connected to the common connection terminal of the first resistor, the second resistor, and the Zener diode. The second end of the switching transistor is electrically connected to the signal sampling and feedback unit. The third end of the switching transistor is connected to the 24VP1 power supply side.

4. The fuel metering valve isolation drive and anti-interference protection circuit according to claim 3, characterized in that: The switching transistor is a VSD045P10MS P-channel MOSFET.

5. The fuel metering valve isolation drive and anti-interference protection circuit according to claim 3, characterized in that: The signal sampling and feedback unit includes a signal conditioning chip. The input terminal of the signal conditioning chip is connected to the switching transistor and the fuel metering valve, respectively. The output terminal of the signal conditioning chip is shaped by a filtering unit and outputs a current feedback signal to the ECU main control chip.

6. The fuel metering valve isolation drive and anti-interference protection circuit according to claim 5, characterized in that: The filtering unit consists of a third resistor, a first filtering capacitor, and a second filtering capacitor connected together. The common terminal of the third resistor and the first filtering capacitor is connected to the output terminal of the signal conditioning chip, and the common terminal of the third resistor and the second filtering capacitor is connected to the ECU main control chip.

7. The fuel metering valve isolation drive and anti-interference protection circuit according to claim 5, characterized in that: The signal conditioning chip is a BS6023-5B model chip.

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