JP2019027408A - Solenoid valve driving device - Google Patents

Abstract

To provide a solenoid valve driving device capable of improving detection accuracy of valve opening of a fuel injection valve.SOLUTION: A solenoid valve driving device includes a driving circuit for driving a solenoid valve from a valve closing state to a valve opening state by supplying a first voltage of a power source device to a solenoid coil of the solenoid valve, a regeneration circuit for regenerating the detection current as electric current caused by counter electromotive force generated in the solenoid coil, to the ground after stopping the supply of the first voltage, and a valve opening detection portion for detecting valve opening of the solenoid valve on the basis of the detection current detected by the current detecting portion.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a solenoid valve driving device.

Patent Document 1 below discloses an electromagnetic fuel injection device that opens a fuel injection valve by supplying a battery voltage (hereinafter referred to as “battery voltage”) to the fuel injection valve.
The electromagnetic fuel injection device described in Patent Document 1 is based on a change in current (hereinafter referred to as “drive current”) flowing through the fuel injection valve when battery voltage is supplied to the fuel injection valve. The opening of the fuel injection valve is detected.

Japanese Patent Laid-Open No. 2001-221121

  By the way, when the battery voltage fluctuates, the drive current of the fuel injection valve changes. For this reason, the electromagnetic fuel injection device described in Patent Document 1 misidentifies a change in drive current due to a change in battery voltage as a change in drive current due to the opening of the fuel injection valve. The detection accuracy may be reduced.

  This invention is made | formed in view of such a situation, The objective is to provide the solenoid valve drive device which can improve the detection accuracy of the valve opening in a fuel injection valve.

  One aspect of the present invention is an electromagnetic valve driving device that drives an electromagnetic valve, and the first voltage of a power supply device is supplied to a solenoid coil of the electromagnetic valve for a predetermined period, thereby closing the electromagnetic valve. A drive circuit for driving from a state to a valve open state, and a regeneration circuit for regenerating a detection current, which is a current caused by a counter electromotive force generated in the solenoid coil, to the ground after the supply of the first voltage is stopped A current detection unit that detects a detection current regenerated in the ground, and a valve opening detection unit that detects the opening of the electromagnetic valve based on the detection current detected by the current detection unit. It is an electromagnetic valve drive device characterized by these.

  One aspect of the present invention is the above-described electromagnetic valve driving device, wherein the valve opening detecting unit detects the inflection point in the second-order differential value of the detected current, thereby opening the electromagnetic valve. Is detected.

  One aspect of the present invention is the above-described electromagnetic valve drive device, wherein the regenerative circuit includes a switching element connected between one end of the solenoid coil and a ground, and controls the switching element to an on state. Then, a regenerative control unit that regenerates the detected current to the ground is further provided.

  One aspect of the present invention is the above-described electromagnetic valve drive device, wherein the drive circuit has a lower voltage than the first voltage when the valve opening detector detects the valve opening. A voltage of 2 is supplied to the solenoid coil.

  One aspect of the present invention is the above-described electromagnetic valve driving device, wherein the predetermined period is a threshold value in which a current flowing through the solenoid coil after the first voltage is supplied to the solenoid coil is set in advance. It is a period until it exceeds.

  One aspect of the present invention is the above-described electromagnetic valve driving device, wherein the electromagnetic valve is a fuel injection valve that injects fuel in an internal combustion engine.

  As described above, according to the present invention, the detection accuracy of the valve opening in the fuel injection valve can be improved.

It is a schematic block diagram of the fuel injection valve L which concerns on one Embodiment of this invention. It is a schematic structure figure of fuel injection valve drive device 1 concerning one embodiment of the present invention. It is a timing chart which shows operation | movement of the fuel injection valve drive device 1 which concerns on one Embodiment of this invention. It is a figure which shows the peak H of an inflexion point in the 2nd-order differential value of the drive current value which the fuel injection valve drive device 1 which concerns on one Embodiment of this invention detects.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The fuel injection valve drive device 1 according to the present embodiment is a drive device that drives a fuel injection valve L as shown in FIG. That is, the fuel injection valve drive device 1 according to the present embodiment is an electromagnetic valve drive device that drives a fuel injection valve L (electromagnetic valve) that injects fuel into an internal combustion engine mounted on a vehicle.

The fuel injection valve L is an electromagnetic valve (solenoid valve) that injects fuel into an internal combustion engine such as a gasoline engine or a diesel engine mounted on a vehicle.
First, the schematic configuration of the fuel injection valve L will be described with reference to FIG.

  As shown in FIG. 1, the fuel injection valve L includes a fixed core 2, a valve seat 3, a solenoid coil 4, a needle 5, a valve body 6, a retainer 7, a lower stopper 8, a valve body biasing spring 9, a movable core 10, and A movable core biasing spring 11 is provided. In the present embodiment, the fixed core 2, the valve seat 3, and the solenoid coil 4 are fixed members, and the needle 5, the valve body 6, the retainer 7, the lower stopper 8, the valve body biasing spring 9, the movable core 10, and the movable core The biasing spring 11 is a movable member.

  The fixed core 2 is a cylindrical member and is fixed to a housing (not shown) of the fuel injection valve L. The fixed core 2 is made of a magnetic material.

The valve seat 3 is fixed to the housing of the fuel injection valve L. The valve seat 3 has an injection hole 3a.
The injection hole 3 a is a hole through which fuel is injected, and is closed when the valve body 6 is seated on the valve seat 3, and is opened when the valve body 6 is separated from the valve seat 3.

The solenoid coil 4 is formed by winding an electric wire in an annular shape. The solenoid coil 4 is disposed concentrically with the fixed core 2.
The solenoid coil 4 is electrically connected to the fuel injection valve driving device 1. The solenoid coil 4 is energized from the fuel injection valve driving device 1 to form a magnetic path including the fixed core 2 and the movable core 10.

  The needle 5 is a long bar member extending along the central axis of the fixed core 2. The needle 5 moves in the axial direction of the central axis of the fixed core 2 (the direction in which the needle 5 extends) by the attractive force generated by the magnetic path including the fixed core 2 and the movable core 10. In the following description, in the axial direction of the central axis of the fixed core 2, the direction in which the fixed core 2 moves due to the suction force is referred to as “upward”, and the direction opposite to the direction in which the fixed core 2 moves due to the suction force. Called downward.

  The valve body 6 is formed at the lower tip of the needle 5. The valve body 6 closes the injection hole 3 a by being seated on the valve seat 3, and opens the injection hole 3 a by being separated from the valve seat 3.

The retainer 7 includes a guide member 71 and a flange 72.
The guide member 71 is a cylindrical member fixed to the upper tip of the needle 5.
The flange 72 is formed so as to protrude in the radial direction of the needle 5 at the end portion of the guide member 71 on the upper side.
The lower end surface of the flange 72 is a contact surface with the movable core urging spring 11. The upper end surface of the flange 72 is a contact surface with the valve body biasing spring 9.

  The lower stopper 8 is a cylindrical member fixed to the needle 5 between the valve seat 3 and the guide member 71. In the lower stopper 8, the upper end surface is a contact surface with the movable core 10.

  The valve body biasing spring 9 is a compression coil spring housed in the fixed core 2 and is interposed between the inner wall surface of the housing and the flange 72. The valve body biasing spring 9 biases the valve body 6 downward. That is, when the coil 14 is not energized, the valve body 6 is brought into contact with the valve seat 3 by the biasing force of the valve body biasing spring 9.

The movable core 10 is disposed between the guide member 71 and the lower stopper 8. The movable core 10 is a cylindrical member and is provided coaxially with the needle 5. The movable core 10 has a through-hole through which the needle 5 is inserted at the center, and is movable along the extending direction of the needle 5.
An upper end surface of the movable core 10 is a contact surface with the fixed core 2 and the movable core biasing spring 11. On the other hand, the lower end surface of the movable core 10 is a contact surface with the lower stopper 8. The movable core 10 is made of a magnetic material.

  The movable core biasing spring 11 is a compression coil spring that is interposed between the flange 72 and the movable core 10. The movable core biasing spring 11 biases the movable core 10 downward. That is, the movable core 10 is brought into contact with the lower stopper 8 by the biasing force of the movable core biasing spring 11 when power is not supplied to the solenoid coil 4.

Next, the fuel injection valve drive device 1 according to one embodiment of the present invention will be described.
As shown in FIG. 2, the fuel injector driving device 1 includes a booster circuit 20, a first switching element 21 to a fourth switching element 24, a first diode 25, a second diode 26, and a current detection resistor. 27 and a control unit 28. The booster circuit 20 according to the present embodiment is an example of the “power supply device” in the present invention. The first switching element 21, the second switching element 22, the fourth switching element 24, and the second diode 26 constitute a “drive circuit” of the present invention. Further, the third switching element 23 and the first diode 25 constitute a “regenerative circuit” of the present invention.

The booster circuit 20 is a chopper circuit that boosts the battery voltage input from the battery BT mounted on the vehicle to a predetermined target voltage (boosted voltage), and generates a predetermined boosted voltage. This boosted voltage is an example of the “first voltage” in the present invention.
The step-up circuit 20 has a step-up ratio of about ten to several tens, for example, and its operation is controlled by the control unit 28.

The first switching element 21 is, for example, a MOS transistor, and is provided between the output terminal of the booster circuit 20 and one end of the solenoid coil 4. That is, in the first switching element 21, the drain terminal is connected to the output terminal of the booster circuit 20, the source terminal is connected to one end of the solenoid coil 4, and the gate terminal of the first switching element 21 is controlled. Connected to the unit 28.
On / off (close / open) operation of the first switching element 21 is controlled by the control unit 28.

The second switching element 22 is, for example, a MOS transistor, and is provided between the output end of the battery BT and one end of the solenoid coil 4. That is, in the second switching element 22, the drain terminal is connected to the cathode terminal of the second diode 26, and the source terminal is connected to one end of the solenoid coil 4. The gate terminal of the second switching element 22 is connected to the control unit 28.
The second switching element 22 is controlled to be turned on / off (closed / opened) by the control unit 28.

The third switching element 23 is, for example, a MOS transistor, and has a drain terminal connected to one end of the solenoid coil 4 and a source terminal connected to GND (reference potential). The gate terminal of the third switching element 23 is connected to the control unit 28.
The third switching element 23 is controlled to be turned on / off (closed / opened) by the controller 28. The third switching element 23 is a switch for forming the path of the regenerative current by being turned on (opened).

  The fourth switching element 24 is, for example, a MOS transistor, connected to the other end of the solenoid coil 4, and has a source terminal connected to one end of the current detection resistor 27. The gate terminal of the fourth switching element 24 is connected to the control unit 28. The fourth switching element 24 is controlled to be turned on / off (closed / opened) by the control unit 28.

  The first diode 25 has a cathode terminal connected to the output terminal of the booster circuit 20 and an anode terminal connected to the other end of the solenoid coil 4.

  The second diode 26 is a backflow preventing diode having a cathode terminal connected to the drain terminal of the second switching element 22 and an anode terminal connected to the output terminal of the battery BT. The second diode 26 prevents the output current of the booster circuit 20 from flowing into the output terminal of the battery BT when both the first switching element 21 and the second switching element 22 are turned on. It is an auxiliary part for.

  The current detection resistor 27 is a shunt resistor having one end connected to the source terminal of the fourth switching element 24 and the other end connected to GND (reference potential). That is, the current detection resistor 27 is connected in series to the solenoid coil 4 via the fourth switching element 24, and the detection current supplied from the solenoid coil 4 passes therethrough. In such a current detection resistor 27, a voltage (detection voltage) corresponding to the magnitude of the detection current is generated between one end and the other end.

The control unit 28 controls the booster circuit 20 and the first switching element 21 to the fourth switching element 24 based on a command signal input from the host control system, for example, an integrated circuit (IC). is there.
The control unit 28 includes a boost control unit 30, a drive control unit 31, a current detection unit 32, and a valve opening detection unit 33.

  The step-up control unit 30 generates a step-up control signal (PWM signal) for controlling the operation of the step-up circuit 20 and outputs it to the step-up circuit 20.

The drive control unit 31 includes an energization control unit 311 and a regeneration control unit 312.
The energization control unit 311 controls the on state and the off state of the first switching element 21. Specifically, the energization control unit 311 generates a first gate signal for controlling the first switching element 21 and outputs the first gate signal to the gate terminal of the first switching element 21. To do. Thereby, the 1st switching element 21 will be in an ON state.

The energization control unit 311 controls the on state and the off state of the second switching element 22. Specifically, the energization control unit 311 generates a second gate signal for controlling the second switching element 22 and outputs the second gate signal to the gate terminal of the second switching element 22. To do. As a result, the second switching element 22 is turned on.
The energization control unit 311 controls the on state and the off state of the fourth switching element 24. Specifically, the energization control unit 311 generates a fourth gate signal for controlling the fourth switching element 24 and outputs the fourth gate signal to the gate terminal of the fourth switching element 24. To do. As a result, the fourth switching element 24 is turned on.

  The regeneration control unit 312 controls the on state and the off state of the third switching element 23. Specifically, the regeneration control unit 312 generates a third gate signal for controlling the third switching element 23 and outputs the third gate signal to the gate terminal of the third switching element 23. To do. Thereby, the 3rd switching element 23 will be in an ON state.

  The current detection unit 32 includes a pair of input ends, one input end is connected to one end of the current detection resistor 27, and the other input end is connected to the other end of the current detection resistor 27. That is, the current detection unit 32 receives the detection voltage generated by the current detection resistor 27. The current detection unit 32 detects (calculates) the detection current based on the detection voltage.

  The valve opening detection unit 33 detects the opening of the fuel injection valve L based on the detection current input from the current detection unit 32. Specifically, the valve opening detection unit 33 specifies the inflection point H in the second-order differential value of the detected current detected by the current detection unit 32 during the regeneration, so that the fuel injection valve L is opened. Detect that

  Next, the operation of the fuel injection valve driving apparatus 1 according to one embodiment of the present invention will be described in detail with reference to FIGS.

  When the fuel injection valve driving apparatus 1 drives the fuel injection valve L from the closed state to the open state, the energization control unit 311 has an initial period T1 (from time t0 to t1) at the start of driving, as shown in FIG. In the period, the boosted voltage (first voltage) generated by the booster circuit 20 is supplied to the fuel injection valve L. That is, in the initial period T 1, the boost control unit 30 outputs a boost control signal to the boost circuit 20, thereby causing the boost circuit 20 to output a predetermined boost voltage. The initial period T1 is an example of the “predetermined period” in the present invention. For example, the initial period T1 is a period from when the first voltage is supplied to the solenoid coil 4 until the current flowing through the solenoid coil 4 exceeds a preset threshold value.

  In the initial period T1, the energization control unit 311 supplies the boosted voltage to one end of the solenoid coil 4 by outputting the first gate signal to the gate terminal of the first switching element 21, and the fourth period By outputting the fourth gate signal to the switching element 24, the other end of the solenoid coil 4 is connected to GND (reference potential) via the current detection resistor 27.

  As a result, in the initial period T1, a relatively high boosted voltage is supplied to the solenoid coil 4 as shown in FIG. Such a drive current forms a magnetic path including the fixed core 2 and the movable core 10, and moves the movable core 10 to the fixed core 2 side (upward) by an attractive force generated by the magnetic path. That is, the needle 5 moves upward by the suction force caused by the drive current, and thus the valve body 6 is separated from the valve seat 3.

  Here, in the initial period T1, the boosted voltage (first voltage) higher than the battery voltage (second voltage) is used because the rising of the drive current is accelerated to open the fuel injection valve L. This is for speeding up the operation. That is, in the initial period T1, the valve opening speed of the fuel injection valve L is increased by the drive current as compared with the case where the battery voltage is used.

  When the initial period T1 elapses, the energization control unit 311 stops the output of the first gate signal and stops the supply of the boosted voltage to the solenoid coil 4. In this case, the first switching element 21, the second switching element 22, and the third switching element 23 are in the off state, and the fourth switching element 24 is in the on state.

  The regeneration control unit 312 sends the third gate signal to the gate terminal of the third switching element 23 in the regeneration period T2 from time t1 to time t3 when the supply of the boosted voltage to the solenoid coil 4 is stopped by the energization control unit 311. By outputting, the current caused by the back electromotive force of the solenoid coil 4 is regenerated to GND (ground) as a detection current.

  Specifically, when the third switching element 23 is controlled to be in the ON state by the regeneration control unit 312, GND, the third switching element 23, the solenoid coil 4, the first coil are generated by the back electromotive force generated in the solenoid coil 4. The detection current caused by the back electromotive force flows to the GND via the switching element 24 and the current detection resistor 27.

  Here, in such a regeneration period T2, the electromotive voltage of the solenoid coil 4 gradually decreases with the passage of time as the detection current flows. The detected current gradually attenuates as shown in FIG. 3 mainly due to the decrease in the electromotive voltage, but the movable core 10 continues to move toward the fixed core 2 and finally collides with the fixed core 2. The collision timing of the movable core 10 to the fixed core 2 is time t2 in FIGS.

  In addition, the movement of the movable core 10 causes a change in the magnetic coupling state between the movable core 10 and the fixed core 2. Therefore, the inductance of the solenoid coil 4 gradually changes as the movable core 10 moves. The inductance of the solenoid coil 4 changes drastically when the movable core 10 collides with the fixed core 2. As a result, a specific change occurs in the detection current when the movable core 10 collides with the fixed core 2. As shown in FIG. 4, the change in the detected current becomes clearer by performing second-order differentiation. That is, at the timing when the movable core 10 collides with the fixed core 2, an inflection point H at which the curvature changes from positive (+) to negative (−) appears in the second-order differential value of the detected current.

  Therefore, the valve opening detection unit 33 according to the present embodiment detects the inflection point H in the second-order differential value of the detected current detected by the current detection unit 32 as the valve opening timing of the fuel injection valve L during the regeneration period T2. To do.

  In the second-order differential value of the detected current, an inflection point at which the curvature changes from negative (−) to positive (+) as shown in FIG. 4 appears before the inflection point H. The inflection point H indicates the timing at which the moving speed from the bottom to the top of the movable core 10 decreases due to the valve body biasing spring 9 or the drag of the fuel, and the movable core 10 is in a relatively stable state. The state is not in contact with the fixed core 2, that is, the state in which the movable core 10 is seated on the fixed core 2. That is, the movable core 10 moves from the bottom to the top, but stops at a position where the movable core 10 abuts (contacts) the fixed core 2 by its own kinetic energy. In the present embodiment, this contact (contact) position is considered as the valve opening position (valve opening timing) of the fuel injection valve L.

  Further, in the second-order differential value of the detected current, some inflection points appear after the inflection point H. These inflection points are due to minute vibrations of the movable core 10 with respect to the fixed core 2. Yes, no need to consider.

  When the valve opening detection unit 33 detects the opening of the fuel injection valve L in this way, the energization control unit 311 holds the battery voltage lower than the boosted voltage (second state) in order to maintain the valve opening state of the fuel injection valve L. Is output to the solenoid coil 4. That is, the energization control unit 311 supplies the battery voltage to one end of the solenoid coil 4 by outputting the second gate signal to the second switching element 22 in the holding period T3. Here, in the holding period T3, the first switching element 21 and the third switching element 23 are in the off state, and the second switching element 22 and the fourth switching element 24 are in the on state.

  Here, since the energization control unit 311 supplies a PWM signal having a predetermined duty ratio to the second switching element 22 as a second gate signal, the battery voltage is intermittently supplied to the solenoid coil 4. The duty ratio is set based on the magnitude of the detected current detected by the current detector 32. In other words, the energization control unit 311 sets a duty ratio of the PWM signal based on the magnitude of the detected current detected by the current detection unit 32, so that a holding current for maintaining the open state of the fuel injection valve L is predetermined. Feedback control is performed to maintain the target value.

  As a result, as shown in FIG. 3, a constant holding current flows through the solenoid coil 4 during the holding period T3, whereby the open state of the fuel injection valve L is held. Further, the drive current may be changed stepwise by changing the duty ratio to two steps in the holding period T3.

  As described above, the fuel injection valve drive device 1 according to one embodiment of the present invention detects the opening of the fuel injection valve L based on the detected current in the regeneration period T2, that is, the influence of the fluctuation of the battery voltage. Since the opening of the fuel injection valve L is detected in the regeneration period T2 that is not received, the detection accuracy of the opening of the fuel injection valve L can be improved.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) Although the present embodiment has described the detection of the opening of the fuel injection valve L, the present invention is not limited to this. The present invention is also applicable to valve opening detection of electromagnetic valves other than the fuel injection valve L.

(2) In this embodiment, the inflection point H in the second-order differential value of the detected current is set as the valve opening timing of the fuel injection valve L, but the present invention is not limited to this. For example, an inflection point that appears before the inflection point H, that is, an inflection point at which the curvature changes from negative (−) to positive (+) may be used as the valve opening timing.

(3) In the present embodiment, the battery voltage is the second voltage, but the present invention is not limited to this. That is, in the present invention, the energization control unit 311 may supply the voltage lower than the boosted voltage to the solenoid coil 4 as the second voltage in the holding period T3, and the battery voltage is set to a voltage lower than the first voltage. The second voltage may be generated by boosting.

L Fuel injection valve (solenoid valve)
1 Fuel injection valve drive device (solenoid valve drive device)
2 Fixed Core 3 Valve Seat 3a Injection Hole 4 Solenoid Coil 5 Needle 6 Valve Body 7 Retainer 8 Lower Stopper 9 Valve Body Energizing Spring 10 Movable Core 11 Movable Core Energizing Spring 20 Booster Circuit (Power Supply Device)
21 1st switching element 22 2nd switching element 23 3rd switching element 24 4th switching element 25 1st diode 26 2nd diode 31 Drive control part 33 Valve opening detection part 311 Energization control part 312 Regeneration control Part

Claims (6)

A solenoid valve driving device for driving a solenoid valve,
A drive circuit for driving the electromagnetic valve from the closed state to the open state by supplying a first voltage of the power supply device to the solenoid coil of the electromagnetic valve in a predetermined period;
A regeneration circuit that regenerates a detection current, which is a current caused by a counter electromotive force generated in the solenoid coil, to the ground after the supply of the first voltage is stopped;
A current detection unit for detecting a detection current regenerated to the ground;
Based on the detected current detected by the current detector, a valve opening detector that detects opening of the solenoid valve;
An electromagnetic valve driving device comprising:   The solenoid valve driving device according to claim 1, wherein the valve opening detection unit detects that the solenoid valve is opened by detecting an inflection point in a second-order differential value of the detection current. The regenerative circuit is
A switching element connected between one end of the solenoid coil and the ground;
The electromagnetic valve drive device according to claim 1, further comprising a regeneration control unit that regenerates the detected current to the ground by controlling the switching element to be in an ON state.   The said drive circuit supplies the 2nd voltage lower than a said 1st voltage to the said solenoid coil, when the valve opening detection part detects the valve opening of an electromagnetic valve, The said 1st voltage is supplied to the said solenoid coil. The electromagnetic valve drive device according to any one of claims 3 to 4.   5. The predetermined period is a period from when the first voltage is supplied to the solenoid coil to when a current flowing through the solenoid coil exceeds a preset threshold value. The electromagnetic valve drive device according to one item.   The electromagnetic valve driving device according to claim 1, wherein the electromagnetic valve is a fuel injection valve that injects fuel in an internal combustion engine.

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