JP5605379B2 - Solenoid valve drive - Google Patents

Description

  The present invention relates to an electromagnetic valve drive device for driving an electromagnetic valve.

  As a conventional electromagnetic valve drive device, for example, one disclosed in Patent Document 1 is known. This solenoid valve drive device (hereinafter simply referred to as “drive device”) includes a solenoid valve and a first switch element connected in series between a power source and a ground, and a first signal is received from a drive circuit. The electromagnetic valve is driven by turning on the switch element, and the electromagnetic valve is stopped by turning off the first switch element.

  In addition, a second switch element is connected in parallel to the solenoid valve, and a third switch element and a Zener diode connected in series with each other are further connected in parallel to the solenoid valve. The second and third switch elements are turned on / off by a signal from the drive circuit.

  In this drive device, the first switch element is turned off and then the second switch element is turned on, whereby the current caused by the induced electromotive force generated in the coil of the electromagnetic valve is transferred to the circuit passing through the second switch element. The induced electromotive force is eliminated by the Zener diode by reducing the flow rate by refluxing and turning off the second switch element and turning on the third switch element.

US Pat. No. 7,301,749

  However, in the drive device according to the above-described patent document, there is a possibility that the drive of the electromagnetic valve may be hindered. For example, when the time from when the solenoid valve is stopped to when it is driven again is short, the induced electromotive force is not completely erased until the solenoid valve is driven again, and magnetic flux is generated in the solenoid valve coil. It will remain. As a result, in addition to the voltage of the power supply, the electromotive force due to the residual magnetic flux affects the drive of the solenoid valve, and there is a possibility that the solenoid valve cannot be driven appropriately.

  The present invention has been made to solve the above-described problems, and can stably drive a solenoid valve even when the interval from when the solenoid valve is stopped to when it is driven is short. It aims at providing the drive device of a solenoid valve.

  In order to achieve the above object, an electromagnetic valve drive device according to the present invention supplies a power supply voltage from a power supply, thereby providing an electromagnetic valve provided between the power supply and a reference voltage portion having a voltage lower than the power supply voltage. An electromagnetic valve drive device for driving a valve, provided between the electromagnetic valve and a reference voltage unit, and a switch element for turning on / off the supply of power supply voltage to the electromagnetic valve, and an electromagnetic valve Between the time when the switch element is switched from on to off to stop the operation and the time when the switch element is switched from off to on to drive the electromagnetic valve, the conduction between the power source and the electromagnetic valve is interrupted, Electromotive force erasing means for turning on the switch element only for a predetermined period in order to erase the induced electromotive force remaining in the electromagnetic valve.

  According to this drive device, in order to drive the solenoid valve, when the switch element provided on the reference voltage unit side from the solenoid valve is turned on, conduction between the power source and the reference voltage unit is ensured, and By supplying the power supply voltage, the electromagnetic valve is driven. On the other hand, when the switch element is turned off, the supply of the power supply voltage is cut off, so that the solenoid valve is controlled to be stopped.

  In addition, before the switch element is turned on to drive the solenoid valve, the electromotive force erasing means cuts off the conduction between the power source and the solenoid valve, and the switch element is temporarily turned on for a predetermined period. Thus, the solenoid valve is connected to the reference voltage section having a lower voltage for a predetermined period. During a predetermined period when the switch element is turned on, a current based on the induced electromotive force generated in the solenoid valve when the switch element is turned off to stop the solenoid valve flows to the reference voltage unit via the switch element. As a result, the induced electromotive force is quickly erased. As a result, when the switch element is turned on to drive the solenoid valve, the power supply voltage is supplied to the solenoid valve without being affected by the induced electromotive force of the solenoid valve, and the electromagnetic current is generated by a current having a magnitude based on the power supply voltage. The valve is driven.

  As described above, the switch between the time when the solenoid valve is stopped and the time when the solenoid valve is driven is cut off by connecting the solenoid valve and the reference voltage unit for a predetermined period. The induced electromotive force generated in the electromagnetic valve when the element is turned off can be reliably erased. As a result, since the current due to the induced electromotive force has already disappeared when driving the solenoid valve, the solenoid valve can be driven stably without being affected by the induced electromotive force based on the power supply voltage. .

It is the circuit diagram which shows the drive device of the solenoid valve which concerns on 1st Embodiment, and the figure which shows the return path | route of a flyback current. FIG. 2 is a circuit diagram of FIG. 1 and a diagram illustrating a flyback current return path when residual electromotive force is erased. 3 is a timing chart showing an example of the operation of the drive device of FIG. 1. 2 is a timing chart showing a comparative example of the drive device of FIG. 1. It is a circuit diagram which shows the drive device of the solenoid valve which concerns on 2nd Embodiment, and a figure which shows the return path | route of a flyback current. FIG. 6 is a circuit diagram of FIG. 5 and a diagram illustrating a flyback current return path when residual electromotive force is erased. 6 is a timing chart showing an example of the operation of the drive device of FIG. 5. FIG. 6 is a circuit diagram according to a comparative example of the drive device of FIG. 5 and a diagram showing a flyback current return path. 6 is a timing chart showing a comparative example of the drive device of FIG.

  Hereinafter, a drive device for a solenoid valve according to a first embodiment of the present invention will be described with reference to the drawings. The drive device 1 according to the present embodiment is provided in a vehicle (none of which is shown) equipped with a common rail type diesel engine, and this vehicle includes an electronic control device 10 for controlling the diesel engine. . The drive device 1 is provided in the electronic control device 10 and, as shown in FIG. 1, a power supply unit 2 that outputs a power supply voltage VB from a battery (not shown), and a voltage lower than that of the power supply unit 2. A reference voltage unit 3, a booster circuit 4 that boosts and outputs the power supply voltage VB, a control circuit 5, and the like are provided. The control circuit 5 is configured by a microcomputer, a control IC other than the microcomputer, or a combination thereof.

  The booster circuit 4 has a coil L and a first switch SW1 connected in series between the power supply unit 2 and the reference voltage unit 3. The first switch SW1 is composed of an N-channel MOSFET, and its drain is connected to the reference voltage unit 3 and its source is connected to one terminal of the coil L. The other terminal of the coil L is connected to the power supply unit 2.

  A first diode D1 and a capacitor C are connected in parallel to the first switch SW1. The first diode D1 and the capacitor C are connected in series with each other, the first diode D1 is provided on the power supply unit 2 side, and the capacitor C is provided on the reference voltage unit 3 side. The anode of the first diode D1 is connected to the power supply unit 2 side, and the cathode is connected to one electrode of the capacitor C.

A control circuit 5 is connected to the gate of the switch element SW1. The control circuit 5
For example, a pulse width modulation signal (hereinafter referred to as “PWM signal”) is generated and output to the gate of the first switch SW1. Accordingly, the first switch SW1 is turned on / off according to the duty ratio of the PWM signal. When current is passed through the coil L when the first switch SW1 is turned on, energy is accumulated. Due to the induced electromotive force generated in the coil L when the first switch SW1 is turned off, a voltage larger than the power supply voltage VB is generated. It is output from the output terminal 11 between D1 and the capacitor C.

  Further, the driving device 1 includes a second switch SW2 (electromotive force erasing means), a solenoid valve coil LV1, and a third switch SW3 (switch element) connected in series between the booster circuit 4 and the reference voltage unit 3. I have. The coil LV1 constitutes a part of a relief valve PRV (electromagnetic valve) provided on a common rail (not shown), and the relief valve PRV is generated by a magnetic force generated based on a current supplied to the coil LV1. The valve is opened. The second switch SW2 on the booster circuit 4 side of the coil LV1 is composed of an N-channel MOSFET, and is configured to withstand the voltage boosted by the booster circuit 4, and its drain is boosted. The source is connected to the output terminal 11 of the circuit 4 to the coil LV1. The control circuit 5 is connected to the gate, and the second switch SW2 is turned on / off according to the duty ratio of the PWM signal supplied from the control circuit 5 to the gate.

  The third switch SW3 closer to the reference voltage unit 3 than the coil LV1 is also composed of an N-channel MOSFET, and its drain is connected to the coil LV1 and its source is connected to the reference voltage unit 3. In response to the PWM signal supplied from the control circuit 5 connected to the gate. In addition, the freewheeling diode DR1 is provided in parallel with the second switch SW2 and the coil LV1. The anode of the freewheeling diode DR1 is connected to the intermediate terminal 13 between the coil LV1 and the third switch SW3, and the cathode is connected to the intermediate terminal 12 between the booster circuit 4 and the second switch SW2. .

  Further, an intermediate terminal 14 is provided between the second switch SW2 and the coil LV1, and a second diode D2 is provided between the intermediate terminal 14 and the reference voltage unit 3. The anode of the second diode D2 is connected to the reference voltage unit 3, and the cathode is connected to the intermediate terminal 14. Further, a third diode D3 and a fourth switch SW4 (electromotive force erasing means) are connected in series between the intermediate terminal 14 and the power supply unit 2. The cathode of the third diode 3 is connected to the intermediate terminal 14 side.

  The fourth switch SW4 is composed of a P-channel type MOSFET, and has a source connected to the power supply unit 2 and a drain connected to the anode of the third diode D3. The control circuit 5 is connected to the gate of the fourth switch SW4, and the fourth switch SW4 is turned on / off according to the duty ratio of the PWM signal supplied from the control circuit 5.

  A plurality of injectors (not shown) are connected to the output terminal 11 of the booster circuit 4. These are driven by the power supply voltage VB boosted by the booster circuit 4, and high pressure fuel boosted by a fuel pump (not shown) and stored in the common rail is injected into the combustion chamber (not shown) of the cylinder. To do. Further, a fuel pressure sensor 6 is provided on the common rail, and this fuel pressure sensor 6 outputs a detection signal indicating the pressure of the fuel in the common rail (hereinafter referred to as “rail pressure RP”) to the control circuit 5.

  In addition, the control circuit 5 described above constitutes an electromotive force erasing unit in the present embodiment, and includes an I / O interface, a CPU, a RAM, a ROM, and the like (all not shown). Detection signals from various sensors such as the fuel pressure sensor 6 are input to the CPU after A / D conversion and shaping by the I / O interface. In accordance with these input signals, the CPU executes various control processes such as the above-described fuel injection control by the injector and the drive control of the relief valve PRV in accordance with a control program stored in the ROM.

  In the drive device 1 configured as described above, the control circuit 5 drives the relief valve PRV so that the rail pressure RP is maintained at a predetermined target rail pressure. Specifically, by energizing the coil LV1 according to the rail pressure RP, the relief valve PRV is appropriately opened so that the rail pressure RP does not become excessive. Thereby, the fuel flows back from the common rail to the fuel tank (not shown), and the rail pressure RP is reduced and maintained at the target rail pressure.

  Hereinafter, the operation of the drive device 1 described above will be described with reference to FIG. FIG. 2 is a timing chart showing an example of the operation of the driving device 1. As shown in the figure, when all of the second to fourth switches SW2 to SW4 are turned off, the coil LV1 is not energized, and the relief valve PRV is controlled to be stopped, that is, closed. .

  From this state, when a drive request for the relief valve PRV occurs at timing t1, the second and third switches SW2 and SW3 are turned on to establish conduction between the output terminal 11 of the booster circuit 4 and the reference voltage unit 3. Secured. As a result, the boosted power supply voltage VB is supplied to energize the coil LV1, and the magnitude of a current (hereinafter referred to as “drive current”) flowing through the coil LV1 increases rapidly. As a result, the relief valve PRV is opened.

  At timing t2, by turning off the second switch SW2 and turning on the fourth switch SW4, the conduction between the booster circuit 4 and the coil LV1 is cut off, while the power supply unit 2 and the reference voltage unit 3 are connected to the coil. By being connected via LV1, the power supply voltage VB is supplied to the coil LV1, and a smaller current is supplied almost stably. Thereby, the open state of the relief valve PRV is maintained.

  At timing t3, both the third and fourth switches SW3 and SW4 are turned off. Thereby, the conduction between the power supply unit 2 and the coil LV1 is interrupted, and the drive current to the coil LV1 is stopped, whereby the relief valve PRV is controlled to be closed. At this time, an electromotive force is generated in the coil LV1 due to the inductance of the coil LV1, and a current based on the induced electromotive force (hereinafter, such a current is referred to as “flyback current”) flows through the first return path R1. Specifically, as shown by a thick line in FIG. 1, the return from the coil LV1 to the return diode DR1, the intermediate terminal 12, the output terminal 11, the capacitor C, the reference voltage unit 3, the second diode D2, and the intermediate terminal 14 in that order. A flyback current flows. This flyback current gradually attenuates along with the induced electromotive force of the coil LV1 due to leakage from the return path R1.

  Then, at the timing t4 immediately after the third and fourth switches SW3 and SW4 are turned off, the third switch SW3 is temporarily turned on again to ensure conduction between the coil LV1 and the reference voltage unit 3. The third switch SW3 is turned off at a timing t5 when a predetermined period T1 has elapsed from the timing t4. In this predetermined period T1, the path through which the flyback current described above changes and flows to the second return path R2. That is, as indicated by a thick line in FIG. 2, a flyback current flows from the coil LV1 through the intermediate terminal 13, the third switch SW3, the reference voltage unit 3, the second diode D2, and the intermediate terminal 14 in this order. Thereby, the induced electromotive force remaining in the coil LV1 is quickly erased. The predetermined period T1 is set to a very short time (for example, 200 μsec), as long as it can secure a time sufficient to erase the remaining induced electromotive force.

  When the drive request for the relief valve PRV is generated at the timing t6 when the period T2 has elapsed from the timing t3 at which the relief valve PRV is controlled to be closed, and the relief valve PRV is driven again, the control circuit 5 performs the timing t6 to At t10, the second to fourth switches are turned on / off similarly to the timings t1 to t5 described above. Thereby, the rail pressure RP is controlled to become the target rail pressure, and the induced electromotive force generated in the coil LV1 is eliminated. The period T2 is calculated by the control circuit 5 according to the rail pressure RP.

  FIG. 4 is a timing chart showing the operation of the drive device according to the first comparative example. The drive device of this comparative example has a circuit configuration similar to that of the drive device 1 of the first embodiment. When a drive request for the relief valve PRV is generated in order to maintain the rail pressure RP at the target rail pressure, As shown in the figure, the second to fourth switches SW2 to SW4 are turned on / off between timings t11 to t13 in the same manner as the timings t1 to t3 of the first embodiment described above.

  When the drive request for the relief valve PRV occurs again at the timing t14 when the period T3 has elapsed from the timing t13, the second to fourth switches SW2 to SW4 are turned on from the timing t14 to t16, similarly to the timing t11 to t13. / Turn off. At this time, if the period T3 is sufficiently large and sufficient time has passed for the induced electromotive force of the coil LV1 to disappear, the relief valve PRV can be driven without any trouble. On the other hand, when the drive request for the relief valve PRV is made before the period T3 is small and the induced electromotive force of the coil LV1 disappears, not only the voltage from the booster circuit 4 but also the remaining induction in the drive current flowing through the coil LV1 The flyback current based on the electromotive force has an effect, and the drive current increases more steeply as shown by the broken line in FIG.

  As a result, the opening timing of the relief valve PRV varies between the case where the induced electromotive force disappears and the case where it remains, which may hinder the control of the rail pressure RP to the target rail pressure. Occurs. On the other hand, in the drive device 1 according to the first embodiment, as described above, immediately after the relief valve PRV is controlled to be closed, the third switch SW3 is turned on for a predetermined time T1 to induce the coil LV1. The electromotive force is erased, and control is performed so that the induced electromotive force does not affect the subsequent drive of the relief valve PRV.

  As described above, according to the driving device 1 according to the first embodiment, the second and fourth switches SW2 and SW4 are turned off between the time when the relief valve PRV is controlled to be closed and the time when the relief valve PRV is driven again. As a result, the conduction between the power supply unit 2 and the coil LV1 is cut off, and the third switch SW3 is turned on for a predetermined period T1. As a result, the induced electromotive force generated in the coil LV1 when the relief valve PRV is controlled to be closed can be quickly erased, and is not affected by the induced electromotive force when the relief valve PRV is driven next time. Based on the voltage from the booster circuit 4, the relief valve PRV can be driven stably. As a result, even when the period T1 from the stop of the relief valve PRV to the drive is short, the rail pressure RP can be stably maintained at the target rail pressure.

  FIG. 5 shows a drive device 1a according to the second embodiment. Unlike the first embodiment, the drive device 1a of the present embodiment includes a coil LV2 and a fifth switch SW5 (switch element) provided in parallel to the coil LV1 and the third switch SW3 of the relief valve PRV. Hereinafter, the same reference numerals are given to the same components as those of the driving device 1 according to the first embodiment described above, and the driving device 1a of the second embodiment will be described focusing on differences from the driving device 1.

  The coil LV2 constitutes a part of the prestroke valve PCV (solenoid valve). The prestroke valve PCV controls the amount of fuel sucked from the fuel pump to the common rail, and is opened by a magnetic force generated based on the magnitude of the current supplied to the coil LV2.

  The fifth switch SW5 is composed of an N-channel type MOSFET, the source of which is connected to one terminal of the coil LV2, and the drain of which is connected to the reference voltage unit 3. Further, the control circuit 5 is connected to the gate of the fifth switch SW5, and the fifth switch is turned on / off according to the duty ratio of the PWM signal supplied from the control circuit 5, and the coil LV2 is accordingly turned on. Energization controls the opening and closing of the prestroke valve PCV.

  Further, a free-wheeling diode DR2 is provided between the output terminal 11 of the booster circuit 4 and the intermediate terminal 12 between the second switch SW2 and the intermediate terminal 16 between the coil LV2 and the fifth switch SW5. The anode is connected to the intermediate terminal 16 and the cathode is connected to the intermediate terminal 12.

  Further, the control circuit 5 controls on / off of the second to fifth switches SW2 to SW5 as described later so that the relief valve PRV and the prestroke valve PCV are alternately driven. Other configurations are the same as those of the first embodiment described above.

  FIG. 7 is a timing chart showing an example of the operation of the driving device 1a. As shown in the figure, when the second to fifth switches SW2 to SW5 are all off and the coils LV1 and LV2 are not energized, the relief valve PRV and the prestroke valve PCV are both controlled to be closed. ing. From this state, when the relief valve PRV is driven according to the rail pressure RP, the relief valve PRV is controlled by controlling the second to fourth switches SW2 to SW4 from timing t21 to t25 in the same manner as in the first embodiment. Is opened and closed, the rail pressure RP is controlled to the target rail pressure, and the induced electromotive force remaining in the coil LV1 is erased.

  At that time, when the relief valve PRV is controlled to be closed at the timing t23, a flyback current flows through the first return path R1 and a third return path R3 described later, and when the third switch SW3 is turned on at the timing t24, A flyback current flows through the second reflux path R2. During this time, since there is no request for driving the prestroke valve PCV, the fifth switch SW5 is kept off.

  When the third switch SW3 is turned off at the timing t23 and the relief valve PRV is controlled to be in the closed state, when the driving request for the prestroke valve PCV is generated at the timing t26 when the period T4 has elapsed, the second and fifth The switches SW2 and SW5 are turned on. As a result, the power supply voltage VB boosted by the booster circuit 4 is supplied to the coil LV2 of the prestroke valve PCV, and the current supplied to the coil LV2 increases rapidly, thereby opening the prestroke valve PCV. Then, at timing t27, the second switch SW2 is turned off and the fourth switch SW4 is turned on to cut off the conduction between the booster circuit 4 and the coil LV2, and the power supply unit 2 supplies the power supply voltage VB to the coil LV2. Is done. As a result, a substantially constant drive current is supplied to the coil LV2, and the prestroke valve PCV is maintained in the open state.

  At timing t28, the fourth and fifth switches SW4 and SW5 are both turned off, and the voltage supply to the coil LV2 is interrupted. At this time, an electromotive force is generated in the coil LV2 due to the inductance of the coil LV2, and a flyback current based on the induced electromotive force flows through the third return path R3 and the first return path R1. In the third return path R3, as indicated by a thick line in FIG. 5, from the coil LV2, the intermediate terminal 16, the return diode DR2, the intermediate terminal 12, the output terminal 11, the capacitor C, the reference voltage unit 3, the second diode D2, and A flyback current flows in the order of the intermediate terminals 14. As a result, the induced electromotive force of the coil LV2 is gradually attenuated over time.

  Then, at the timing t29 to t30 immediately after the timing t28 when the prestroke valve PCV is controlled to be closed, the fifth switch SW5 is turned on for a predetermined time T1, thereby causing the induction remaining in the coil LV2 as in the case of the coil LV1. Erase the electromotive force. At this time, the return path of the flyback current changes, and the flyback current flows through the fourth return path R4. Specifically, as indicated by a thick line in FIG. 6, a flyback current flows from the coil LV2 to the intermediate terminal 16, the fifth switch SW5, the reference voltage unit 3, the second diode D2, and the intermediate terminal 14 in this order. Thereby, the induced electromotive force of the coil LV2 is quickly erased.

  Then, from timing t31 to t35, the relief valve PRV is driven similarly to timing t21 to t25, and thereafter, the above-described driving of the prestroke valve PCV and the relief valve PRV is alternately performed.

  8 and 9 show a drive device according to a second comparative example. The drive device of the second comparative example has a circuit configuration similar to that of the drive device 1a of the second embodiment. As shown in FIG. 9, when the drive request for the relief valve PRV occurs, Similarly to the timings t21 to t23 of the second embodiment, the second to fourth switches SW2 to SW4 are turned on / off between the timings t41 to t43.

  Then, when the period T4 elapses from the timing t43 and a drive request for the pre-stroke valve PCV is generated, the second, fourth and fifth switches are performed from the timing t44 to t46 in the same manner as the timing t26 to t28 in the second embodiment. SW2, SW4 and SW5 are turned on / off. At this time, if the period T4 is sufficiently long and sufficient time has passed for the induced electromotive force of the coil LV1 of the relief valve PRV to disappear, the relief valve PRV is reliably controlled to be closed, and the circuit is controlled to fly. The prestroke valve PCV can be driven in a state where the back current is not energized.

  On the other hand, when the period T4 is short and a drive request for the prestroke valve PCV occurs before the induced electromotive force of the coil LV1 disappears, the flyback current is shown between the timing t44 and the timing t55 as shown in FIG. Also flows to the fifth reflux path R5 indicated by a bold line in FIG. This is because the second switch SW2 is turned on at timing t44. Specifically, in the fifth return path R5, from the coil LV1, the intermediate terminal 13, the return diode DR1, the intermediate terminal 12, The flyback current circulates in the order of the two switches SW2 and the intermediate terminal 14.

  As a result, in addition to the current based on the voltage from the booster circuit 4, a larger current flows through the second switch SW2 by the amount of the flyback current, thereby increasing the heat generation in the second switch SW2 and adversely affecting its durability. There is a risk of effects. Moreover, there is a risk that radio noise from the circuit will deteriorate due to the increase in the return path of the flyback current on which the high voltage acts.

  In addition, even if the period T4 from when the prestroke valve PCV is driven from timing t44 to t46 until the relief valve PRV is driven again is short to eliminate the induced electromotive force of the coil LV2, the relief valve PRV is restarted. The flyback current from the coil LV2 also flows through the sixth return current R6 between the timing t47 at which the driving of the current is started and the timing t48. Specifically, the flyback current flows from the coil LV2 in the order of the intermediate terminal 16, the return diode DR2, the intermediate terminal 12, the second switch SW2, and the intermediate terminal 14. Therefore, as in the case of timing t44 to t45, there is a possibility that heat generation at the second switch SW2 increases and radio noise deteriorates.

  On the other hand, in the drive device 1a according to the second embodiment, as described above, immediately after the relief valve PRV is controlled to be closed, the third switch SW3 is turned on for a predetermined time T1 to induce the coil LV1. The electromotive force is erased to prevent the influence of the induced electromotive force remaining in the coil LV1 when the prestroke valve PCV is driven immediately after that. Similarly, immediately after the prestroke valve PCV is controlled to be in the closed state, the fifth switch SW5 is turned on only for a predetermined time T1, so that the influence of the induced electromotive force of the coil LV2 is caused when the relief valve PRV is driven immediately after that. It is prevented from occurring.

  As described above, according to the driving device 1a according to the second embodiment, the second and fourth switches SW2 and SW4 are between the time when the relief valve PRV is controlled to be closed and the time when the prestroke valve PCV is driven. Since the third switch SW3 is turned on for a predetermined time T1 in a state where is turned off, the induced electromotive force generated in the coil LV1 when the relief valve PRV is controlled to be closed can be quickly erased. Thereby, even when the interval from the stop of the relief valve PRV to the start of driving of the prestroke valve PCV is short, it is not affected by the induced electromotive force of the coil LV1, and based on the voltage from the booster circuit 4, The stroke valve PCV can be driven stably.

  Similarly, between the time when the prestroke valve PCV is controlled to the closed state and the time when the relief valve PRV is driven next, the fifth switch SW5 is turned on for a predetermined time with the second and fourth switches SW2 and SW4 turned off. Since only T1 is turned on, the induced electromotive force of the coil LV2 can be quickly erased, and the relief valve PRV can be stably driven based on the voltage from the booster circuit 4.

  Further, since the residual magnetic fluxes of the coils LV2 and LV1 can be quickly erased before the start of driving of the relief valve PRV and before the start of driving of the prestroke valve PCV, respectively, the relief valve PRV and the prestroke valve PCV When the driving of is started, it is possible to prevent the flyback current from flowing through the fifth or sixth return path R5, R6. Accordingly, it is possible to prevent an unnecessary flyback current from flowing through the second switch SW2, and thus heat generation at the second switch SW2 can be suppressed. In addition, since the flyback current is not applied to the fifth and sixth return paths R5 and R6, it is possible to prevent the generation of radio noise from them.

  In each of the above-described embodiments, the relief valve PRV and the prestroke valve PCV have been described as electromagnetic valves that are driven by the voltage from the booster circuit 4. However, the present invention is not limited to these and is based on the voltage from the booster circuit. You may apply this invention to the drive device of the other solenoid valve to drive. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 Drive 2 Power supply unit (Power supply)
3 Reference voltage section 5 Control circuit (electromotive force erasing means)
VB power supply voltage SW2 second switch (electromotive force erasing means)
SW3 3rd switch (switch element)
SW4 4th switch (electromotive force erasing means)
SW5 5th switch (switch element)
T1 predetermined period

Claims (3)

By supplying a power supply voltage (VB) from a power supply (2), an electromagnetic valve for driving an electromagnetic valve provided between the power supply and a reference voltage section (3) having a lower voltage than the power supply voltage A drive device (1) comprising:
Switch elements (SW3, SW5) provided between the solenoid valve and the reference voltage unit for turning on / off the supply of the power supply voltage to the solenoid valve;
Between the time when the switch element is switched from on to off to stop the solenoid valve and the time when the switch element is switched from off to on to drive the solenoid valve, the power source, the solenoid valve, The electromotive force is erased by turning on the switch element for a predetermined period (T1) in order to eliminate the induced electromotive force generated in the electromagnetic valve when the switch element is switched off. Means (SW2, SW4, control circuit 5);
A drive device for a solenoid valve, comprising: A plurality of the solenoid valves;
A plurality of the switch elements respectively provided between the plurality of solenoid valves and the reference voltage unit;
With
2. The electromagnetic valve driving device according to claim 1, wherein the electromotive force erasing unit turns on the plurality of switch elements for the predetermined period for each of the plurality of electromagnetic valves.   The electromotive force erasing means is any one of the plurality of solenoid valves from when any one of the solenoid valves is stopped to when the solenoid valve other than any one of the solenoid valves is driven. 3. The drive device for an electromagnetic valve according to claim 2, wherein the switch element provided between the electromagnetic valve and the reference voltage unit is turned on only for the predetermined period.

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