JP7459578B2 - Solenoid valve drive circuit - Google Patents

Description

The present disclosure relates to a drive circuit for a solenoid valve.

Conventionally, a drive circuit for this type of solenoid valve has been proposed that has a switching element connected in series to a DC power source and the electromagnetic part of the solenoid valve, and a diode connected in parallel to the electromagnetic part and the switching element (see, for example, Patent Document 1). In this solenoid valve drive circuit, the energization of the electromagnetic part of the solenoid valve is controlled by switching the switching element.

JP 2007-27465 A

If the solenoid valve drive circuit and other electric circuits are connected in parallel from the DC power source, if power is no longer supplied from the DC power source to the solenoid valve drive circuit while the solenoid valve's electromagnetic part is energized, the solenoid valve As the current continues to flow through the electromagnetic section, the potential on the DC power supply side of the electromagnetic section decreases to a negative value. Along with this, current tends to flow from the other electric circuit side to the drive circuit side of the solenoid valve, which may have an inappropriate effect on other electric circuits (switching elements, etc.).

The main purpose of the drive circuit for the solenoid valve disclosed herein is to prevent the DC power source from having an inappropriate effect on other electrical circuits connected in parallel to the drive circuit.

The solenoid valve drive circuit disclosed herein employs the following means to achieve the above-mentioned primary objective:

The driving circuit of the solenoid valve of the present disclosure includes:
A drive circuit for a solenoid valve that receives power from a DC power source to control energization of an electromagnetic part of a solenoid valve,
a first connection point, a second connection point, and a switching element that are arranged in this order from a DC power source side on a power line that connects the DC power source and the electromagnetic unit;
a diode having a cathode connected to the second node;
Equipped with
The first connection point is connected to another electric circuit,
The power supply unit further includes a cutoff circuit that is installed between the first connection point and the second connection point of the power line and that is capable of cutting off current flow from the second connection point side to the first connection point side.
The gist of the present invention is as follows.

The drive circuit of the solenoid valve disclosed herein includes a first connection point, a second connection point, a switching element, and a diode having a cathode connected to the second connection point, which are arranged in this order from the DC power source side on a power line connecting the DC power source and the electromagnetic part. The first connection point is connected to another electric circuit. The drive circuit also includes a cutoff circuit that is installed between the first connection point and the second connection point of the power line and can cut off the current from the second connection point side to the first connection point side. As a result, when power is no longer supplied from the DC power source to the drive circuit of the solenoid valve while the electromagnetic part is energized, the cutoff circuit can cut off the current from the second connection point side (electromagnetic part side) to the first connection point side (other electric circuit side), thereby suppressing current flow to other electric circuits and suppressing inappropriate effects on other electric circuits.

1 is a schematic configuration diagram of a drive device 10 having a drive circuit 30 for a solenoid valve SL of the present disclosure. FIG. 2 is a schematic configuration diagram of a drive device 10B of a first comparative embodiment. It is a schematic block diagram of 10 C of drive devices of a 2nd comparative form. An explanatory diagram showing an example of the source and gate potentials Vs1, Vg1, Vs2, and Vg2 of the FET 42 when power is no longer supplied to the drive circuit 30 etc. from the DC power supply 12 while the electromagnetic part EM of the solenoid valve SL is energized. It is.

Next, embodiments for carrying out the invention of the present disclosure will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a drive device 10 having a drive circuit 30 for a solenoid valve SL according to the present disclosure. The drive device 10 according to the present disclosure is mounted on a vehicle that transmits power from a drive source to a drive shaft connected to a drive wheel via a power transmission device, and includes a DC power source 12, a solenoid valve SL and other loads LD[i] (i: a variable corresponding to each load), and an electronic control unit (ECU) 20, as shown in the figure. Examples of the power transmission device include a stepped transmission, a forward/reverse switching mechanism and a continuously variable transmission, a dual clutch transmission, and a hybrid transmission. The power transmission device is supplied with hydraulic oil by a hydraulic control device. The hydraulic control device has a valve body having multiple oil passages formed therein, a regulator valve, a pressure adjusting valve, a switching valve, and multiple solenoid valves including a solenoid valve SL.

The DC power supply 12 is configured, for example, as a lead acid battery or a lithium ion secondary battery having a rated voltage of 12V. The positive terminal of this DC power supply 12 is connected to the power line 14 via the connector 13, and the negative terminal of the DC power supply 12 is grounded (the power line 14 is connected to a power line such as a metal case). connected to different power lines). The power line 14 connects the DC power supply 12 and the electromagnetic part EM, and the power line 14 is provided with a switch 15. This switch 15 is turned on and off in conjunction with an ignition switch (start switch).

The electronic control unit 20 includes a drive circuit 30 for the solenoid valve SL, a drive circuit DC[i] for each load LD[i], and a microcomputer (hereinafter referred to as "microcomputer") 50. Here, the drive circuit 30 is provided between the connection point P1 on the electromagnetic part EM side of the switch 15 in the power line 14 and the electromagnetic part EM, and each drive circuit DC[i] is connected to the connection point of the power line 14. Connected to P1. Therefore, the drive circuit 30 and each drive circuit DC[i] are connected in parallel to each other when viewed from the DC power supply 12. Here, the "other electric circuits" of the present disclosure, that is, the electric circuits connected to the connection point P1, include each drive circuit DC[i], a power generation circuit (not shown), a rotation sensor circuit, a communication circuit, etc. is applicable.

Examples of the solenoid valve SL include an on-off solenoid valve and a linear solenoid valve. This solenoid valve SL has an electromagnetic part (solenoid part) EM, and a plunger and a spool (both not shown) that are movable parts that are moved in the axial direction by the electromagnetic part EM. One terminal of the electromagnetic part EM is grounded, and the other terminal of the electromagnetic part EM is connected to the power line 14 (drive circuit 30).

The drive circuit 30 includes a switching circuit 31 having a switching element 32, a diode 34, and a cutoff circuit 40. Examples of the switching circuit 31 include an IPD (Intelligent Power Device), which is an IC (Integrated Circuit) that has built-in protection circuits against overheating, overcurrent, etc., and a general IC that does not have a protection circuit. The switching element 32 is connected in series to the electromagnetic part EM of the solenoid valve SL.

The diode 34 is connected in parallel to the switching circuit 31 (switching element 32) and the electromagnetic part EM of the solenoid valve SL. Specifically, the anode of the diode 34 is grounded, and the cathode of the diode 34 is connected to the connection point P2 between the switching element 32 and the connection point P1 of the power line 12.

The cutoff circuit 40 is provided between the connection point P1 and the connection point P2 of the power line 14, and includes a P-channel type FET (Field Effect Transistor) 42, resistance elements 44 and 46, and a capacitor 48. The FET 42 has parasitic capacitances Cgs and Cgd (not shown) between the gate and the source and between the gate and the drain. The source of the FET 42 is connected to the connection point P1, and the drain is connected to the connection point P2. One terminal of the resistive element 44 is connected to the power line 14 between the source of the FET 42 and connection point P1, and the other terminal of the resistive element 44 is connected between the gate of the FET 42 and one terminal of the resistive element 46. It is connected to the. The other terminal of resistance element 46 is grounded. One terminal of the capacitor 48 is grounded, and the other terminal of the capacitor 48 is connected to the other terminal of the resistive element 44, the gate of the FET 42, and one terminal of the resistive element 46. The capacitance of the capacitor 48 is set to a value sufficiently larger than the parasitic capacitances Cgs and Cgd of the FET 42.

In this cutoff circuit 40, the resistive element 44 and the resistive element 46 are connected in series with the source of the FET 42 and the ground, so when power is supplied from the DC power supply 12 to the drive circuit 30, the resistive element 44 and the resistive element 46 are connected in series to the source of the FET 42 and the ground. The relationship between the source potential Vs and the gate potential Vg is determined according to the resistance ratio of the resistance elements 44 and 46.

Examples of the load LD[i] include solenoid valves similar to the solenoid valve SL, various auxiliary machines, and the like. As each drive circuit DC[i], for example, a switching circuit similar to the switching circuit 31 can be mentioned.

The microcomputer 50 has a CPU, ROM, RAM, and input/output ports, and operates by receiving power from the DC power supply 12 via a power line (not shown). Signals from various sensors are input to the microcomputer 50 via input ports. Examples of the various sensors include a current sensor (not shown) that detects the current flowing through the electromagnetic part EM of the solenoid valve SL, a voltage sensor (not shown) that detects the voltage of the DC power supply 12, and the like. The microcomputer 50 outputs control signals to various control objects via output ports. Examples of various controlled objects include the switching element 32 of the switching circuit 31 and the drive circuit DC[i].

Therefore, in the drive device 10, the power line 14 connecting the DC power supply 12 and the electromagnetic part EM is arranged with, in order from the DC power supply 12 side, a switch 15, a connection point P1, a cutoff circuit 40, a connection point P2, and a switching element 32 of a switching circuit 31, and the drive circuit DC[i] of each load LD[i] and the like are connected to the connection point P1, and the cathode of a diode 34 is connected to the connection point P2.

In the drive device 10 configured in this manner, the microcomputer 50 sets the target current Iem* of the electromagnetic portion EM of the solenoid valve SL based on the driver's accelerator operation amount, the state of the power transmission device, etc. The target duty D* of the switching element 32 is set so that Iem becomes the target current Iem*, and the switching of the switching element 32 is controlled using the set target duty D*. In this way, the energization of the electromagnetic part EM is controlled. The microcomputer 50 also sets the target state (target current and target voltage) of the load LD[i] based on the accelerator operation amount, the state of the power transmission device, etc., and sets the state (current and voltage) of the load LD[i]. The drive circuit DC[i] is drive-controlled so that it reaches the target state.

Next, the operation of the drive device 10 will be described, particularly the operation when power is no longer supplied from the DC power source 12 to the drive circuit 30 and each drive circuit DC[i] while the electromagnetic part EM of the solenoid valve SL is energized. Causes of power being no longer supplied from the DC power source 12 to the drive circuit 30, etc., include, for example, the turning off of the switch 15 when the ignition switch is turned off, a poor connection between the DC power source 12 and the power line 14 due to vehicle vibration, and a break in the portion of the power line 14 between the connector 13 and the connection point P1.

Figure 2 is a schematic diagram of the drive device 10B of the first comparative embodiment, and Figure 3 is a schematic diagram of the drive device 10C of the second comparative embodiment. The drive device 10B of the first comparative embodiment differs from the drive device 10 of the embodiment in that the drive circuit 30 of the electronic control unit 20 is replaced with the drive circuit 30B of the electronic control unit 20B. The drive circuit 30B differs from the drive circuit 30 in that it does not have a cutoff circuit 40 (connection point P1 and connection point P2 are directly connected). The drive device 10C of the second comparative embodiment differs from the drive device 10 of the embodiment in that the cutoff circuit 40 of the drive circuit 30 of the electronic control unit 20 is replaced with the cutoff circuit 40C of the drive circuit 30C of the electronic control unit 20C. The cutoff circuit 40C differs from the cutoff circuit 40 in that it does not have a capacitor 48.

In the embodiment, the first comparative embodiment, and the second comparative embodiment, when power is no longer supplied from the DC power source 12 to the drive circuits 30, 30B, 30C, etc. while the electromagnetic part EM of the solenoid valve SL is energized, the electromotive force (induced electromotive force) generated in the electromagnetic part EM causes current to continue to flow in the circuit of the diode 34, the switching element 32, the electromagnetic part EM, and ground, and the potential of the connection point P2 drops to a negative value. At this time, even if the microcomputer 50 turns off the switching element 32, if the electromotive force generated in the electromagnetic part EM is greater than the withstand voltage of the switching element 32, current continues to flow in the above-mentioned circuit.

In the first comparison mode, since the cutoff circuits 40 and 40C are not provided (the connection point P1 and the connection point P2 are directly connected), the connection point is Current tries to flow to the P2 side. Therefore, there is a possibility that a malfunction may occur in the switching elements of each drive circuit DC[i] and continue. On the other hand, in the embodiment and the second comparative embodiment, by providing the cutoff circuits 40 and 40C, power is not supplied from the DC power supply 12 to the drive circuit 30, etc., and the potentials Vs and Vg of the source and gate of the FET 42 are reduced. When the voltage Vgs between the two falls below the threshold value, the FET 42 is turned off, and the connection point P1 and the connection point P2 are electrically cut off. Thereby, it is possible to suppress the current from flowing from each drive circuit DC[i] side to the connection point P2 side via the connection point P1 (even if it flows, it can be suppressed from continuing). As a result, it is possible to suppress inappropriate influences on the drive circuit DC[i] and the like.

Figure 4 is an explanatory diagram showing an example of the state of the source and gate potentials Vs1, Vg1, Vs2, and Vg2 of the FET 42 when power is no longer supplied from the DC power source 12 to the drive circuit 30, etc. while the electromagnetic part EM of the solenoid valve SL is energized in the drive device 10, 10C of the embodiment and the second comparative embodiment. In the figure, the solid line shows the state of the source and gate potentials Vs1, Vg1 of the FET 42 of the embodiment, and the dashed line shows the state of the source and gate potentials Vs2, Vg2 of the FET 42 of the second comparative embodiment.

In the embodiment and the second comparative embodiment, when power is not supplied from the DC power source 12 to the drive circuit 30 and the like while the electromagnetic part EM of the solenoid valve SL is energized (time t1), the source and gate potentials Vs1, Vg1, Vs2, and Vg2 of the FET 42 drop. At this time, the source potentials Vs1 and Vs2 of the FET 42 drop in the same way in the embodiment and the second comparative embodiment. In addition, in the second comparative embodiment, since the cutoff circuit 40C does not have a capacitor 48, the gate potential Vg2 of the FET 42 drops relatively quickly (the amount of drop per unit time is large) due to the influence of the parasitic capacitance Cgd between the gate and drain of the FET 42. Then, when the source and gate potentials Vs2 and Vg2 of the FET 42 drop sufficiently (become negative) and the voltage Vgs between them falls below the threshold value (time t3), the FET 42 turns off and the connection points P1 and P2 are electrically cut off. In contrast, in the embodiment, the shutoff circuit 40 has a capacitor 48 with a capacitance sufficiently larger than the parasitic capacitance Cgd, so the gate potential Vg1 of the FET 42 drops more slowly (the amount of drop per unit time is smaller) than in the second comparative embodiment. As a result, the source-gate voltage Vgs of the FET 42 falls below the threshold (time t2) earlier than in the second comparative embodiment, the FET 42 turns off, and the connection points P1 and P2 are electrically cut off. As a result, in the embodiment, it is possible to more sufficiently suppress inappropriate effects on the drive circuit DC[i] and the like, compared to the second comparative embodiment.

In the embodiment, a drive circuit 30 including a shutoff circuit 40 having an FET 42, resistive elements 44, 46, and a capacitor 48 is used. However, a drive circuit 30C including a second comparative embodiment shutoff circuit 40C having an FET 42 and resistive elements 44, 46 (without a capacitor 48) may also be used. Even in this case, when power is no longer supplied from the DC power source 12 to the drive circuit 30 etc. while the electromagnetic part EM of the solenoid valve SL is energized, it is possible to suppress inappropriate effects on the drive circuit DC[i] etc. compared to the case where a drive circuit 30B of the first comparative embodiment without the shutoff circuits 40, 40C is used.

In the embodiment, the drive circuit 30 for the solenoid valve SL includes a cutoff circuit 40 having an FET 42, resistance elements 44 and 46, and a capacitor 48. However, the configuration of the cutoff circuit 40 is not limited to this, and is provided between the connection point P1 and the connection point P2 of the power line 14, and cuts off current flow from the connection point P2 side to the connection point P1 side. It is fine as long as it is possible.

As described above, the solenoid valve drive circuit of the present disclosure is a solenoid valve (SL) drive circuit (30) that receives power from a DC power source (12) and controls the current supply to the electromagnetic part (EM) of the solenoid valve (SL), and includes a first connection point (P1), a second connection point (P2), a switching element (32), and a diode (34) having a cathode connected to the second connection point (P2) that are arranged in this order from the DC power source (12) side on a power line (14) that connects the DC power source (12) and the electromagnetic part (EM), and the first connection point (P1) is connected to another electric circuit (DC[i]). The gist of the present disclosure is that the drive circuit includes a cutoff circuit (40, 40C) that is installed between the first connection point (P1) and the second connection point (P2) of the power line (14) and is capable of cutting off current supply from the second connection point (P2) side to the first connection point (P1) side.

The drive circuit of the solenoid valve disclosed herein includes a first connection point, a second connection point, a switching element, and a diode having a cathode connected to the second connection point, which are arranged in this order from the DC power source side on a power line connecting the DC power source and the electromagnetic part. The first connection point is connected to another electric circuit. The drive circuit also includes a cutoff circuit that is installed between the first connection point and the second connection point of the power line and can cut off the current from the second connection point side to the first connection point side. As a result, when power is no longer supplied from the DC power source to the drive circuit of the solenoid valve while the electromagnetic part is energized, the cutoff circuit can cut off the current from the second connection point side (electromagnetic part side) to the first connection point side (other electric circuit side), thereby suppressing current flow to other electric circuits and suppressing inappropriate effects on other electric circuits.

In the drive circuit of the solenoid valve of the present disclosure, the cutoff circuit (40, 40C) has a P-channel type field effect transistor having a source connected to the first connection point (P1) side, a drain connected to the second connection point (P2) side, and a gate, a first resistor element (44) and a second resistor element (46), one side of the first resistor element (44) is connected to the power line (14) between the source and the first connection point (P1), the other side of the first resistor element (44) is connected to the gate and one side of the second resistor element (46), and the other side of the second resistor element (46) may be grounded. In this way, when the voltage between the source and gate of the field effect transistor falls below a threshold value, it is possible to cut off the current from the second connection point side to the first connection point side.

In this case, the interruption circuit (40) may further include a capacitor (48), one side of which is grounded, and the other side of which is connected to the other side of the first resistor element (44), the gate, and the one side of the second resistor element (46). In this way, it is possible to more sufficiently prevent inappropriate effects on other electric circuits.

Although the above describes the forms for implementing this disclosure, this disclosure is in no way limited to these embodiments, and it goes without saying that this disclosure can be implemented in various forms without departing from the spirit of this disclosure.

This disclosure can be used in the solenoid valve drive circuit manufacturing industry, etc.

10, 10B, 10C Drive device, 12 DC power supply, 13 Connector, 14 Power line, 15 Switch, 20, 20B, 20C Electronic control unit, 30, 30B, 30C Drive circuit, 31 Switching circuit, 32 Switching element, 34 Diode, 40, 40C Shutdown circuit, 42 FET, 44, 46 Resistance element, 48 Capacitor, 50 Microcomputer, P1, P2 Connection point.

Claims (2)

A drive circuit for a solenoid valve that receives power from a DC power source to control energization of an electromagnetic part of a solenoid valve,
a first connection point, a second connection point, and a switching element that are arranged in this order from a DC power source side on a power line that connects the DC power source and the electromagnetic unit;
a diode having a cathode connected to the second node;
Equipped with
The first connection point is connected to another electric circuit,
a cutoff circuit that is installed between the first connection point and the second connection point of the power line and that is capable of cutting off current flow from the second connection point side to the first connection point side ,
the interrupter circuit includes a P-channel field effect transistor having a source connected to the first connection point, a drain connected to the second connection point, and a gate, a first resistor element, and a second resistor element;
one of the first resistor elements is connected to the power line between the source and the first connection point;
the other end of the first resistor element is connected to the gate and one end of the second resistor element;
The other end of the second resistor element is grounded.
Solenoid valve drive circuit. The solenoid valve drive circuit according to claim 1,
The cutoff circuit further includes a capacitor,
one of the capacitors is grounded;
the other of the capacitors is connected to the other of the first resistance elements, the gate, and the one of the second resistance elements;
Solenoid valve drive circuit.

Images