JP2020188374A - Solenoid valve drive device - Google Patents

Abstract

To provide a solenoid valve drive device that allows a dead time to be set appropriately and maximizes the loss reduction effect even when the characteristics of a connected solenoid valve varies.SOLUTION: In a solenoid valve drive device 1, a solenoid valve 2 is energized by a control circuit 3 from a discharge MOS 4 at a high voltage VH, and then energized by a constant current MOS 8 so as to hold a current Iinj from a low-voltage power supply VB. After the discharge MOS 4 and the constant current MOS 8 are turned off, a reflux MOS 7 is driven on to perform synchronous rectification. After the reflux MOS7 is turned off, a gate voltage Vgs is monitored by a reflux MOS monitor circuit 3c, and when the gate voltage Vgs drops to an off level by a dead time control unit 3d, the end of the dead time is determined. The dead time after turning off the reflux MOS 7 can be set appropriately regardless of the variation of a component such as the solenoid valve 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solenoid valve drive device.

A solenoid valve drive device that drives a solenoid valve that serves as an inductive load employs a synchronous rectification method that uses MOS transistors in order to reduce loss in a recirculation circuit configuration that allows a recirculation current to flow when the solenoid valve is energized. There is.

In this case, it is necessary to provide a dead time during which both the MOS transistor that energizes the solenoid valve and the MOS transistor for reflux are not turned on at the same time. In the dead time setting, the dead time is set by a fixed period so that safe operation can be ensured by assuming variations in the characteristics of the components.

Therefore, the dead time setting depends on the degree of variation in the characteristics of the components. Such a synchronous rectification method is also configured in the power supply circuit system, but in the circuit of the power supply circuit system, since the coil is arranged inside the circuit, it is possible to assume the variation in the coil characteristics in advance. The dead time can be set according to the circuit constant of the coil.

However, in the solenoid valve control device, since it depends on the characteristics of the solenoid valve connected to the outside, a longer dead time is set in consideration of the variation in the characteristics of the corresponding solenoid valve, which is synchronized. There is a circumstance that the loss reduction effect, which is the purpose of the rectification method, cannot be obtained significantly.

Japanese Unexamined Patent Publication No. 2013-204442 Japanese Unexamined Patent Publication No. 2013-251975

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to increase the loss reduction effect by appropriately setting the dead time even when the characteristics of the connected solenoid valve vary. The purpose is to provide a solenoid valve drive device that enables this.

The electromagnetic valve driving device according to claim 1 comprises an energizing MOS transistor (4, 8) provided in an energizing path from a DC power supply to the electromagnetic valve, and a recirculation for passing a recirculation current after the electromagnetic valve is cut off. A MOS transistor (7) and a control circuit (3) for driving and controlling the energized MOS transistor and the recirculation MOS transistor are provided, and the control circuit is gated after turning off at least one of the energized MOS transistor and the recirculation MOS transistor. -The configuration is such that the voltage between the sources is detected, the off state is determined based on the detected voltage, and the dead time period is set.

In the above configuration, when the dead time is set by detecting the voltage between the gate and the source after the freewheeling MOS transistor is turned off, the control circuit drives the energized MOS transistor on to energize the electromagnetic valve and then turns it off. When the recirculation current starts to flow, the recirculation MOS transistor is driven on to flow the recirculation current. The control circuit drives the recirculation MOS transistor off when the recirculation current drops to a predetermined level, and then, when the dead time is reached, the control circuit is turned off when the gate-source voltage of the recirculation MOS transistor drops to the off level. Is determined, and the period up to this point is determined as the end of the dead time. When energizing the energized MOS transistor, the control circuit is turned on at the end of the dead time.

In this way, the control circuit determines the off state of the freewheeling MOS transistor based on the gate-source voltage and sets the dead time. Therefore, compared to the case where the dead time is set with a fixed time, the solenoid valve is included. An appropriate dead time can be set even when the characteristics of the components vary, and the drive control of the solenoid valve can be performed without impairing the loss reduction effect.
Further, by adopting the above configuration, it is possible to always set an appropriate dead time even when the characteristics of the components change due to use.

Even when the dead time is set by detecting the voltage between the gate and source after the energized MOS transistor is turned off, the dead time is set in the same manner by replacing the return MOS transistor with the above effect. Obtainable.

Electrical configuration diagram showing the first embodiment Timing chart Detailed timing chart Electrical configuration diagram showing the second embodiment Detailed timing chart

(First Embodiment)
Hereinafter, a case where the first embodiment of the present invention is applied to a solenoid valve driving device that controls a solenoid valve that injects fuel into an internal combustion engine of a vehicle will be described with reference to FIGS. 1 to 3.

In FIG. 1 showing an electrical configuration, the solenoid valve driving device 1 drives and controls the solenoid valve 2 connected between the output terminals A and B. The solenoid valve drive device 1 controls a drive circuit unit that energizes the solenoid valve 2 by a control circuit 3. In the energization operation, the solenoid valve drive device 1 first applies a high voltage to the solenoid valve 2 by a high-voltage power supply VH to drive it to a predetermined opening degree, and then uses a control circuit 3 to apply a low voltage to the low-voltage power supply VB of the vehicle-mounted battery. A predetermined opening is maintained until the solenoid valve 2 is turned off by applying a constant current to the solenoid valve 2 by applying it by on / off control.

In the solenoid valve drive device 1, the drive circuit of the solenoid valve 2 is configured as follows. The discharge MOS transistor (hereinafter referred to as discharge MOS) 4 is connected between the high-voltage power supply VH and the output terminal A. A series circuit of a cylinder MOS transistor (hereinafter referred to as a cylinder MOS) 5 and a current detection resistor 6 is connected between the output terminal B and the ground. A freewheeling MOS transistor (hereinafter referred to as a freewheeling MOS) 7 is connected between the output terminal A and the ground. The discharge MOS4, the cylinder MOS5, and the reflux MOS7 have parasitic diodes 4a, 5a, and 7a, respectively.

The constant current MOS transistor (hereinafter referred to as constant current MOS) 8 as the energizing MOS transistor is connected in series with the backflow prevention MOS transistor (hereinafter referred to as backflow prevention MOS) 9 between the low voltage power supply VB and the output terminal A. Be connected. The constant current MOS8 and the backflow prevention MOS9 have parasitic diodes 8a and 9a, respectively. The backflow prevention MOS 9 is arranged so that the parasitic diode 9a prevents backflow from the high-voltage power supply VH by connecting the source and drain in the opposite directions.

In the above-mentioned configuration of the drive circuit, the discharge MOS4, the cylinder MOS5, the reflux MOS7, the constant current MOS8, and the backflow prevention MOS9 are used as N-channel MOSFETs, but they can also be appropriately configured by using P-channel MOSFETs. ..

The control circuit 3 includes a MOS drive control unit 3a, a current detection circuit 3b, a reflux MOS monitor circuit 3c, and a dead time control unit 3d. The MOS drive control unit 3a gives a gate drive signal to the discharge MOS4, the cylinder MOS5, the reflux MOS7, the constant current MOS8, and the backflow prevention MOS9 of the drive circuit via resistors 10, 11, 12, 13, and 14, respectively. Drive on and off. The sources of the discharge MOS4 and the constant current MOS8 are connected to the control circuit 3 via capacitors 15 and 16, respectively.

The current detection circuit 3b detects the current flowing through the solenoid valve 2 by the voltage drop generated in the current detection resistor 6 and outputs the current to the MOS drive control unit 3a. The reflux MOS monitor circuit 3c monitors the voltage Vgs between the gate and source of the reflux MOS 7, and outputs the monitor result to the dead time control unit 3d.

The dead time control unit 3d sets the dead time after the freewheeling MOS7 is turned off, and sets the dead time until the constant current MOS8 is turned on next by the gate of the freewheeling MOS7 input from the freewheeling MOS monitor circuit 3c. From the voltage Vgs level between the sources, the off state of the reflux MOS 7 is determined, and the dead time end detection signal is output to the MOS drive control unit 3a.

Next, the operation of the above configuration will be described with reference to FIGS. 2 and 3.
First, the outline of the control in which the drive circuit unit is driven by the control circuit 3 to energize the solenoid valve 2 will be described with reference to FIG. When the solenoid valve drive instruction signal is given, the solenoid valve drive device 1 drives the cylinder MOS 5 on at time t0 by the MOS drive control unit 3a of the control circuit 3, followed by the discharge MOS 4 and the constant current MOS 8. The drive voltages V1 and V2 are output to the gate of.

At this time, the MOS drive control unit 3a turns off the constant current MOS8 in a short time until time t1, energizes the discharge MOS4 until it reaches a predetermined valve opening, and then turns it off at time t2. To do. As a result, the solenoid valve 2 is energized with the current Iinj from the high-voltage power supply VH to the level of the current I1. When the energization of the solenoid valve 2 by the discharge MOS 4 is completed, the back electromotive force of the solenoid valve 2 causes the current Iinj to become a reflux current and continuously flow. The current Iinj of the solenoid valve 2 at this time flows from the parasitic diode 7a of the reflux MOS 7 to the ground side through the solenoid valve 2 and the cylinder MOS 5.

After that, after the discharge MOS 4 is turned off, although not shown in FIG. 2, the reflux MOS 7 is driven on by the MOS drive control unit 3a of the control circuit 3 after a predetermined dead time is maintained. As a result, the current Iinj of the solenoid valve 2 flows through the reflux MOS 7 having a small voltage drop.

Then, at the time t3 when the current Iinj level of the solenoid valve 2 drops to the level of the current I2, the MOS drive control unit 3a of the control circuit 3 applies a low level drive voltage V3 to turn off the reflux MOS 7. After the reflux MOS7 is turned off, the dead time described later is set and controlled by the control circuit 3, and then the constant current MOS8 and the backflow prevention MOS9 are driven on. The on-drive of the constant current MOS8 is driven on and off so that the level of the current Iinj of the solenoid valve 2b holds the current I2 on average. Further, the backflow prevention MOS 9 is continuously controlled to be on.

At this time, the constant current MOS8 and the reflux MOS7 are alternately turned on and off after having a dead time so as not to be turned on at the same time. Then, in this embodiment, after the reflux MOS 7 is turned off, the dead time is controlled by the reflux MOS monitor circuit 3c and the dead time control unit 3d.

After that, when a predetermined energization period elapses, the MOS drive control unit 3a of the control circuit 3 further lowers the current Iinj of the solenoid valve 2 to reach the level of the current I2, and the constant current MOS8 again holds this. And the reflux MOS7 is driven on and off alternately with a dead time. In this way, when the energization for a certain period of time according to the drive instruction is completed, the control circuit 3 turns off the constant current MOS8 at time t4 and ends one driving operation of the solenoid valve 2.

Next, with reference to FIG. 3, the dead time setting process by the control circuit 3 after the reflux MOS 7 is turned off will be described. During the period A shown in FIG. 3, the constant current MOS8 shifts from the on state to the off state while the solenoid valve current Iinj is flowing through the solenoid valve 2 at the level of the current I3 by the constant current MOS8 in FIG. It corresponds to the period from time tx to ty as the period until the time when it changes to the on state again.

In FIG. 3, the control circuit 3 sets the drive voltage V2 to the constant current MOS8 to a low level and operates off when the current Iinj of the solenoid valve 2 reaches a predetermined level at the time tx1 after the time tx1. After that, the control circuit 3 is driven on by applying a high level drive voltage V3 to the reflux MOS 7 at the time tx2 when the preset dead time Tdt0 has elapsed. As a result, the gate voltage Vgs of the reflux MOS 7 rises as shown in FIG. 3 and is turned on, and the current Iinj due to the reflux of the solenoid valve 2 flows.

After that, when the current Iinj of the solenoid valve 2 drops to the threshold current value Is at the time tx3, the control circuit 3 lowers the drive voltage V3 to the reflux MOS 7 and turns it off. As a result, the voltage Vgs between the gate and source of the reflux MOS 7 gradually decreases. In the control circuit 3, the gate-source voltage Vgs of the reflux MOS 7 is monitored by the reflux MOS monitor circuit 3c, and when the voltage Vgs reaches the threshold voltage Vth1 at time tx4, the dead time control unit 3d monitors the reflux MOS 7. The off state is determined, and the dead time Tdt1 ends.

The MOS drive control unit 3a of the control circuit 3 sets the drive voltage V2 to the constant current MOS8 to a high level and drives it on according to the detection of the end time of the dead time Tdt1 from the dead time control unit 3d.

Similarly, similarly, when the constant current MOS8 is off, the control circuit 3 has a predetermined dead time Tdt0 to drive the reflux MOS7 on, and when the reflux MOS7 is off, the reflux MOS monitor circuit 3c and the dead time control unit 3d Therefore, the off of the reflux MOS7 is determined by the gate voltage Vgs, and the constant current MOS8 is driven on repeatedly.

According to this embodiment, the gate voltage Vgs of the freewheeling MOS7 can be monitored by the freewheeling MOS monitor circuit 3c, and the dead time control unit 3d can determine the end time point of the dead time and drive the constant current MOS8. Synchronous rectification can be performed by always providing a short dead time that is optimal and eliminates wasted time.

Further, as a result, even if the characteristics of the component change due to a change in the internal temperature of the solenoid valve drive device 1, for example, an appropriate dead time can be set according to the changed characteristic of the component, and the component can be set. The dead time can be shortened as compared with the conventional case in which the worst value corresponding to the component variation is set in advance as the dead time, and the loss reduction effect can be improved by effectively performing the synchronous rectification.

Further, by reducing the loss in this way, the heat generation of the solenoid valve drive device 1 can be reduced. Therefore, in the fuel injection device using the solenoid valve, multi-stage injection and short interval injection can be realized, and fuel consumption and emission can be achieved. It will be possible to reduce the amount of fuel consumption, downsize the drive unit, and relax measures against heat.

(Second Embodiment)
4 and 5 show the second embodiment, and the parts different from the first embodiment will be described below. In this embodiment, in addition to the dead time of the freewheeling MOS7, the dead time of the discharge MOS4 and the constant current MOS8 as the energizing MOS transistor is also determined from the gate-source voltage.

In FIG. 4, the solenoid valve driving device 20 further includes a discharge MOS monitor circuit 3e and a constant current MOS monitor circuit 3f as a configuration of the control circuit 30. The discharge MOS monitor circuit 3e is provided so as to monitor the voltage Vgs1 between the gate and source of the discharge MOS 4, and outputs the monitor result to the dead time control unit 3d. The constant current MOS monitor circuit 3f is provided so as to monitor the voltage Vgs2 between the gate and source of the constant current MOS8, and outputs the monitor result to the dead time control unit 3d.

The dead time control unit 3d in this embodiment sets the dead time until the constant current MOS8 is driven on after the freewheeling MOS7 is turned off, and after the discharge MOS4 and the constant current MOS8 are turned off, until the freewheeling MOS7 is driven on. Also set the dead time of. Since the dead time setting after the reflux MOS 7 is turned off is the same as that in the first embodiment, the description thereof will be omitted.

Next, the operation of the above configuration will be described.
As shown in FIG. 2 in the first embodiment, when the control circuit 30 is driven off by setting the drive voltage V1 to the discharge MOS 4 at a low level by the MOS control unit 3a at time t2, the discharge MOS 4 is turned off. During that time, the current Iinj continues to flow in the solenoid valve 2, and after the discharge MOS 4 is turned off, the return current of the solenoid valve 2 is in a state of being used for flow through the parasitic diode 7a of the return MOS 7.

The discharge MOS monitor circuit 3e monitors the gate-source voltage Vgs1 of the discharge MOS4, and the dead time control unit 3d reaches the threshold voltage at the level of the voltage Vgs1 from the discharge MOS monitor circuit 3e after time t2. Then, the off state of the discharge MOS 4 is determined to determine the end of the dead time. The MOS control unit 3a applies a high level drive voltage V3 to the reflux MOS 7 and drives it on based on the dead time end determination from the dead time control unit 3d. As a result, the current Iinj of the solenoid valve 2 then flows as a reflux current through the reflux MOS 7 having a small resistance that is turned on.

After that, at time t3 when the current Iinj of the solenoid valve 2 drops to the level of the current I2, the control circuit 30 is lowered to the freewheeling MOS7 by the MOS control unit 3a based on the detection result of the current value from the current detection circuit 3b. A level drive voltage V3 is applied to turn it off. After that, the dead time Tdt1 until the constant current MOS8 is driven on is determined in the same manner as in the first embodiment, and the constant current MOS8 is driven on by the high level drive voltage V2 by the MOS control unit 3a.

Hereinafter, the control circuit 30 similarly performs on / off drive control of the reflux MOS7 and the constant current MOS8 alternately, and the setting of the dead time after the constant current MOS8 is off-driven will be described with reference to FIG. The period A shown in FIG. 5 is a period from the time tx to ty, which is the period from the time tx to the time when the constant current MOS8 shown in FIG. 2 shifts from the on state to the off state and then changes to the on state again. There is.

In FIG. 5, the control circuit 30 is determined by the MOS control unit 3a when the current Iinj of the solenoid valve 2 reaches a predetermined current value Is2 by the detection signal from the current detection circuit 3c at the time tx1 after the time tx1. A low-level drive voltage V2 is applied to the current MOS8 to drive it off. In the control circuit 30, the constant current MOS monitor circuit 3f monitors the gate-source voltage Vgs2 of the constant current MOS8, and when the voltage Vgs2 drops to the threshold voltage Vth2 at time txa, the dead time control unit 3d determines it. The off state of the current MOS 8 is determined, and the dead time Tdt2 ends.

The MOS drive control unit 3a of the control circuit 30 sets the drive voltage V3 to the reflux MOS 7 to a high level and drives it on according to the detection of the end time of the dead time Tdt2 from the dead time control unit 3d. As shown in FIG. 5, the gate voltage Vgs of the recirculation MOS 7 rises and is turned on, and the current Iinj due to the recirculation of the solenoid valve 2 flows to the recirculation MOS 4 having a small resistance.

After that, when the solenoid valve current Iinj drops to the threshold current value Is1 at time tx3, the control circuit 30 lowers the drive voltage V3 to the reflux MOS 7 and turns it off. As a result, the voltage Vgs between the gate and source of the reflux MOS 7 gradually decreases. In the control circuit 30, when the gate-source voltage Vgs of the reflux MOS 7 reaches the threshold voltage Vth1 at time tx4 by the reflux MOS monitor circuit 3c, the dead time control unit 3d determines the off state of the reflux MOS 7 and the dead time Tdt1. It is the end point of.

The MOS drive control unit 3a of the control circuit 30 sets the drive voltage V2 to the constant current MOS8 to a high level and drives it on at time tx4 in response to the detection of the end time of the dead time Tdt1 from the dead time control unit 3d. ..

Similarly, similarly, when the constant current MOS8 is off, the control circuit 30 determines that the constant current MOS8 is off by the gate voltage Vgs2 by the constant current MOS monitor circuit 3f and the dead time control unit 3d, and the end of the dead time Tdt2. Is detected, and the reflux MOS 7 is driven on. Further, when the freewheeling MOS7 is off, the control circuit 30 determines that the freewheeling MOS7 is off by the gate voltage Vgs by the freewheeling MOS monitor circuit 3c and the dead time control unit 3d, detects the end of the dead time Tdt1, and detects the end of the dead time Tdt1. Is repeatedly driven on.

In such a second embodiment, the discharge MOS monitor circuit 3e and the constant current MOS monitor circuit 3f are newly provided, and the dead time is determined from the respective gate voltages Vgs1 and Vgs2 even when the discharge MOS4 and the constant current MOS8 are off. And said. As a result, in addition to the effect of the first embodiment, the dead time setting can be further extended even when the discharge MOS4 and the constant current MOS8 are off, and the reflux MOS7 can be driven on at an appropriate timing, further reducing the loss. Can be improved.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof. For example, the present invention can be modified or extended as follows.

In the first embodiment, the dead time Tdt1 after the freewheeling MOS7 is turned off is set by the gate voltage Vgs, and in the second embodiment, the dead time after the discharge MOS4 and the constant current MOS8 are turned off is also the gate voltage. Although it is set according to Vg1 and Vg2, the setting is not limited to this, and it can be selectively provided as follows.

That is, in addition to the configuration of the first embodiment, the dead time after the constant current MOS8 is turned off is set by the gate voltage Vgs2, or in addition to the configuration of the first embodiment, the dead time of the discharge MOS4 is set to the gate voltage. It is also possible to adopt a configuration such as that set by Vgs1.

Although the present disclosure has been described in accordance with the examples, it is understood that the present disclosure is not limited to the examples and structures. The present disclosure also includes various modifications and modifications within an equal range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are also within the scope of the present disclosure.

In the drawings, 1 and 20 are electromagnetic valve drive devices, 2 are electromagnetic valves, 3 and 30 are control circuits, 3a is a MOS control unit, 3b is a current detection circuit, 3c is a return MOS monitor circuit, and 3d is a dead time control unit. 3e is a discharge MOS monitor circuit, 3f is a constant current MOS monitor circuit, 4 is a discharge MOS transistor (energized MOS transistor), 6 is a current detection resistor, 7 is a freewheeling MOS transistor, and 8 is a constant current MOS transistor (energized MOS transistor). Reference numeral 9 denotes a backflow prevention MOS transistor.

Claims (3)

Energizing MOS transistors (4, 8) provided in the energizing path from the DC power supply to the solenoid valve,
A reflux MOS transistor (7) for passing a reflux current after the solenoid valve is cut off, and
A control circuit (3, 30) for driving and controlling the energized MOS transistor and the freewheeling MOS transistor is provided.
The control circuit is an electromagnetic valve drive device that detects a voltage between a gate and a source after turning off at least the freewheeling MOS transistor, determines an off state based on the detected voltage, and sets a dead time. The control circuit (3) claims that the dead time is set until the gate-source voltage when the freewheeling MOS transistor is turned off becomes equal to or lower than a predetermined level, and the energized MOS transistor (8) is driven on. The solenoid valve driving device according to 1. The control circuit (30) sets the dead time until the time when the gate-source voltage when the energized MOS transistor is off becomes equal to or lower than a predetermined level, and drives the freewheeling MOS transistor on according to claim 1 or 2. The solenoid valve drive device described in.

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