Oil sprayer driving circuit with demagnetization performance

Abstract

The invention discloses a fuel injector driving circuit with demagnetization performance. The fuel injector driving circuit comprises first to fifth switch units, a driving unit and a current conditioning unit, the first end of the fuel injector electromagnetic valve coil is connected with external battery voltage through the first switch unit, grounded through the third switch unit and connected with external driving high voltage through the fifth switch unit. The second end of the oil injector electromagnetic valve coil is connected with external battery voltage through a second switch unit and is grounded through a fourth switch unit; the driving unit is used for controlling the first to fourth switch units; and the current conditioning unit is used for monitoring the current of a solenoid valve coil of the oil sprayer and sending a signal that the current is 0 to the driving unit when the current is monitored to be 0. The method has the advantages that after the current in the follow current loop of the fuel injector is reduced to zero, reverse voltage is applied to the solenoid valve coil to form reverse degaussing current, so that the seating time of the solenoid valve armature is shortened, the actual closing time of the fuel injector is shortened, and the fuel injection characteristic of the fuel injector is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronically controlled fuel injectors for vehicle engines, and in particular to a fuel injector drive circuit with demagnetization performance. Background Art

[0002] When the current automotive engine injector drive circuit is closed, the energy stored in the injector solenoid valve coil is fed back to the boost circuit's output capacitor via a freewheeling diode. Due to the high boost voltage, the current in the solenoid valve coil can be reduced to zero in a short time. Although the current in the coil has dropped to zero, the coil still retains a certain degree of magnetism. This results in a longer delay in the injector solenoid valve's armature seating time, extending the actual injector closing time and negatively affecting the injector's injection characteristics. Summary of the Invention

[0003] The present application provides an injector drive circuit with demagnetization performance, which has the advantage that after the current in the injector freewheeling circuit drops to zero, a reverse voltage is applied to the solenoid valve coil to form a reverse demagnetization current, thereby shortening the time for the solenoid valve armature to seat, shortening the actual closing time of the injector, and improving the injector's injection characteristics.

[0004] The technical solution of this application is: a fuel injector drive circuit with demagnetization performance, comprising: First to fifth switch units; wherein the first end of the injector solenoid valve coil is connected to the external battery voltage through the first switch unit, is grounded through the third switch unit, and is connected to the external driving high voltage through the fifth switch unit; the second end of the injector solenoid valve coil is connected to the external battery voltage through the second switch unit and is grounded through the fourth switch unit; A driving unit having at least four output terminals, each used to control the first to fourth switching units; And a current conditioning unit, which is used to monitor the current of the injector solenoid valve coil and send a current 0 signal to the drive unit when the current is monitored to be 0. When the drive unit receives the current 0 signal, it controls the second switch unit and the fourth switch unit to open.

[0005] Furthermore, the low-voltage side of the first switch unit is grounded through a diode D1 , wherein the first switch unit is connected to the cathode of the diode D1 .

[0006] Furthermore, the low-voltage side of the first switch unit is connected to the first end of the injector solenoid valve coil through the diode D2, wherein the first switch unit is connected to the anode of the diode D2.

[0007] Furthermore, the second end of the injector solenoid valve coil is grounded via a diode D4 , wherein the second end of the injector solenoid valve coil is connected to the cathode of the diode D4 .

[0008] Furthermore, the first end and the second end of the injector solenoid valve coil are connected to the driving high-voltage output end through diodes D5 and D3 respectively. The first end and the second end of the injector solenoid valve coil are connected to the positive poles of diodes D5 and D3 respectively. The driving high-voltage output end is used to connect to a separately provided freewheeling circuit.

[0009] Furthermore, the first to fifth switch units are all MOS tubes.

[0010] Furthermore, the driving unit is a half-bridge pre-driver chip.

[0011] In summary, the beneficial effects of this application are: 1. After the current in the injector's freewheeling circuit drops to zero, a reverse voltage is applied to the solenoid valve coil, generating a reverse demagnetizing current. This shortens the time it takes for the solenoid valve armature to settle, shortening the actual closing time of the injector and improving the injector's injection characteristics. 2. A practical high-pressure common rail injector drive circuit is constructed based on a small number of discrete components. This simple structure requires only a few discrete components. At the moment the injector closes, a reverse demagnetization voltage is applied across the injector solenoid valve coil, rapidly demagnetizing the solenoid valve, reducing injector closing delay and improving the injector's injection characteristics. This circuit offers powerful functionality and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of this application; Figure 2 1 is a phase diagram of a driving circuit in a specific embodiment of the present application. DETAILED DESCRIPTION

[0013] The specific implementation of the present application is described in detail below with reference to the accompanying drawings.

[0014] Example: A fuel injector drive circuit with demagnetization performance, referring to Figure 1 , including first to fifth switching units, a driving unit and a current conditioning unit.

[0015] in, Figure 1 The middle coil L represents the injector solenoid valve coil. The first end of the injector solenoid valve coil is connected to the external battery voltage through the first switch unit, to ground through the third switch unit, and to the external drive high voltage through the fifth switch unit. The second end of the injector solenoid valve coil is connected to the external battery voltage through the second switch unit and to ground through the fourth switch unit. The first through fifth switch units are all MOS transistors, namely MOS transistors T1, T2, T3, T4, and T5, respectively.

[0016] The low-voltage side of the first switch unit is grounded via a diode D1, wherein the first switch unit is connected to the cathode of the diode D1. The low-voltage side of the first switch unit is connected to the first end of the injector solenoid valve coil via a diode D2, wherein the first switch unit is connected to the anode of the diode D2.

[0017] The second end of the injector solenoid valve coil is grounded through a diode D4 , wherein the second end of the injector solenoid valve coil is connected to the cathode of the diode D4 .

[0018] The first end and the second end of the injector solenoid valve coil are connected to the driving high-voltage output end through diodes D5 and D3 respectively. The first end and the second end of the injector solenoid valve coil are connected to the positive poles of diodes D5 and D3 respectively. The driving high-voltage output end is used to connect to a separately provided freewheeling circuit.

[0019] The driving unit has at least four output terminals, which are used to control the first to fourth switching units respectively.

[0020] The current conditioning unit is used to monitor the current of the injector solenoid valve coil and send a current 0 signal to the drive unit when the current is detected to be 0. When the drive unit receives the current 0 signal, it controls the second switch unit and the fourth switch unit to open for a preset time.

[0021] The driving unit is a half-bridge pre-driver chip that controls two groups of driving arms. HO1 and LO1 drive MOS tubes T1 and T4 respectively. This group of MOS tubes is used to modulate the normal injector drive current. HO2 and LO2 drive MOS tubes T2 and T3 respectively. This group of MOS tubes starts working after T1 and T4 are closed and the freewheeling current drops to zero. A reverse voltage is applied to the injector solenoid valve (L) to generate a demagnetization current, promote rapid demagnetization of the solenoid valve coil, accelerate the seating of the solenoid valve armature, reduce the injection delay time, and improve the injection characteristics. The magnitude of the demagnetization current can be determined by the working time of the demagnetization circuit. Since the electromagnetic parameters of various types of injectors are different, this parameter needs to be calibrated in a targeted manner. MOS tube T5 controls the driving high voltage. The entire working phase diagram is as shown below. Figure 2 shown.

[0022] In this embodiment, a diesel engine injector is used as an example. For a diesel injector with a high drive current (48V drive voltage, 25A peak current, 15A first-order current, and 10A second-order current), the half-bridge pre-driver uses the FD6187T half-bridge gate driver chip from Fengqi Technology, the MOS transistor uses the CS25N06C4 from Silan Microtechnology, and the current conditioner uses the SGM832A from Shengbang Microelectronics. When the driver receives a zero current signal, it controls the second and fourth switch units to remain on for 20 to 40µs. For other injector types, the parameters may vary.

[0023] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the creative concept of the present application, and these all fall within the scope of protection of the present application.

Claims

1. A fuel injector drive circuit with demagnetization performance, characterized in that: include: First to fifth switch units; wherein the first end of the injector solenoid valve coil is connected to the external battery voltage through the first switch unit, is grounded through the third switch unit, and is connected to the external driving high voltage through the fifth switch unit; the second end of the injector solenoid valve coil is connected to the external battery voltage through the second switch unit and is grounded through the fourth switch unit; A driving unit having at least four output terminals, each used to control the first to fourth switching units; And a current conditioning unit, which is used to monitor the current of the injector solenoid valve coil and send a current 0 signal to the drive unit when the current is monitored to be 0. When the drive unit receives the current 0 signal, it controls the second switch unit and the fourth switch unit to open.

2. The fuel injector driving circuit with demagnetization performance according to claim 1, characterized in that: The low-voltage side of the first switch unit is grounded through a diode D1 , wherein the first switch unit is connected to the cathode of the diode D1 .

3. The fuel injector driving circuit with demagnetization performance according to claim 1, characterized in that: The low-voltage side of the first switch unit is connected to the first end of the injector solenoid valve coil through the diode D2, wherein the first switch unit is connected to the anode of the diode D2.

4. The fuel injector driving circuit with demagnetization performance according to claim 1, characterized in that: The second end of the injector solenoid valve coil is grounded through a diode D4 , wherein the second end of the injector solenoid valve coil is connected to the cathode of the diode D4 .

5. The fuel injector driving circuit with demagnetization performance according to claim 1, characterized in that: The first end and the second end of the injector solenoid valve coil are connected to the driving high-voltage output end through diodes D5 and D3 respectively. The first end and the second end of the injector solenoid valve coil are connected to the positive poles of diodes D5 and D3 respectively. The driving high-voltage output end is used to connect to a separately provided freewheeling circuit.

6. The fuel injector driving circuit with demagnetization performance according to claim 1, characterized in that: The first to fifth switch units are all MOS tubes.

7. The fuel injector driving circuit with demagnetization performance according to claim 1, characterized in that: The driving unit is a half-bridge pre-driver chip.

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