JP3121304B2 - Solenoid valve driving method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solenoid valve coil,
A solenoid valve driving method in which a large current is supplied for a predetermined period to operate the solenoid valve at a high speed in the initial stage of energization, and a required current of the solenoid valve is maintained by energizing a smaller current after the completion of the large current application. And an apparatus.

[0002]

2. Description of the Related Art For example, as a prior art for controlling the operation of an electromagnetic valve used as a fuel injection control valve in a vehicle fuel injection system, a vehicle fuel injection device described in Japanese Patent Application Laid-Open No. 63-55345 is known. Are known. This is because, when the current flowing through the solenoid valve coil exceeds the first reference value due to the closing of the drive loop, the drive loop of the solenoid valve is cut off by a command from the comparison control means, and the current value flowing through the solenoid valve coil decreases. When the current becomes equal to or less than the second reference value, the flywheel circuit is activated by a command from the comparison control means, and a transmission circuit for outputting the power stored in the solenoid valve coil is formed. Things. According to this driving method, the transition period from the valve opening current for opening the solenoid valve to the holding current for keeping the solenoid valve in the open state is shortened, and the current interruption to the solenoid valve coil is cut off. The fall of the current at the time becomes earlier, and the usable effective fuel injection period can be extended.

However, in this configuration, once the level of the solenoid valve driving current falls below the second reference value, even if the level of the driving current exceeds the second reference value during driving of the solenoid valve thereafter, the flywheel circuit Is inoperative. Therefore, as shown in FIG. 3, when the flywheel drive signal is first turned on from off, the flywheel circuit can prevent an increase in the solenoid valve current caused by the eddy current of the solenoid valve. In other words, a problem occurs that the closing time of the solenoid valve is delayed or fluctuates from a predetermined timing.

[0004]

As described above, in the conventional configuration, after the initial large current for high-speed driving of the solenoid valve once falls below the reference value and enters the holding operation, the driving current of the solenoid valve is reduced. Since the flywheel circuit does not operate even if the reference value is exceeded, when the first flywheel drive signal changes from off to on, the drive current generated by the eddy current generated in the solenoid valve The rise cannot be prevented. As a result, there is a problem that the solenoid valve cannot be driven with good responsiveness because the closing timing of the solenoid valve is delayed or the closing timing varies.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solenoid valve driving device capable of stably supplying a current for holding operation after a large current required for high-speed driving of the solenoid valve to a solenoid valve coil. It is to provide a method and an apparatus.

[0006]

According to the first aspect of the present invention,
A large current is applied to the solenoid valve coil only for a predetermined period immediately after the start of the operation of the solenoid valve, and after the predetermined period has elapsed, the large current flowing through the coil is cut off, and flyback is performed using a back electromotive voltage generated in the coil. After flowing a wheel current as an operation holding current to the coil, in a solenoid valve driving method in which a predetermined operation holding current smaller than the large current is supplied from a power source to the coil for a required period, a low side of the coil is provided. An energization control unit provided to respond to a detection result of a level of a current flowing through the coil during a driving period of the coil by the flywheel current, and to turn on the energization control unit only when the detected level is equal to or lower than a predetermined level; By doing so, an excessive increase in the flywheel current is suppressed.

According to the present invention, the flywheel current is applied to the solenoid valve coil by using the back electromotive force generated in the coil by interrupting the current flowing to the solenoid valve coil at the initial stage of driving the solenoid valve. In the method in which the current is passed as the holding current, if the flywheel current exceeds a predetermined level, the energization control means is turned off, and the level of the flywheel current is reduced. The control means is turned on to prevent the flywheel current from being supplied.
As a result, even if an eddy current occurs in the solenoid valve immediately after the initial stage of driving the solenoid valve, it is possible to effectively prevent the level of the flywheel current flowing through the coil from excessively increasing.

According to a second aspect of the present invention, first and second switching means and a flywheel diode are provided on the high side of the coil of the solenoid valve, and the first switching means is provided for a predetermined period after the start of driving of the solenoid valve. By closing, a large current flows from the power supply unit to the coil, and after the lapse of the predetermined period, a flywheel current due to a back electromotive voltage generated in the coil flows to the coil via the flywheel diode, and the flywheel current is An electromagnetic valve configured to cause a predetermined operation holding current to flow from the power supply unit to the coil by turning on and off the second switching means only for a required period when the level of the predetermined operation holding current becomes smaller than the level of the predetermined operation holding current smaller than the large current. In the driving method, a third switching means is provided on a low side of the coil, and a third switching means is provided for the flywheel current. The flywheel current during the driving period of said coil is characterized in that so as to suppress an excessive increase of the flywheel current by closing the third switching means only when a predetermined level below that.

According to the present invention, the back electromotive force generated in the coil of the solenoid valve by switching the first switching means from on to off in the initial stage of driving the solenoid valve is applied to the flywheel diode via the flywheel diode. When the flywheel current exceeds a predetermined level, the third switching means is turned off to reduce the level of the flywheel current, and when the flywheel current is equal to or lower than the predetermined level, the third switching means is turned off. (3) The switching means is not turned on to prevent the flywheel current from being supplied. As a result, it is possible to effectively prevent the level of the flywheel current flowing through the coil from excessively increasing, so that the influence of the eddy current generated in the solenoid valve immediately after the initial stage of driving the solenoid valve can be suppressed.

According to a third aspect of the present invention, a first switching means and a second switching means provided between a high side of a coil of a solenoid valve and a power supply, a flywheel diode connected to the coil, Turning on the first switching means so that a large current flows through the coil for a predetermined period immediately after the start of driving of the solenoid valve in response to a valve drive signal;
First signal generating means for generating a first control signal for performing off control, and an operation holding current having a level smaller than the large current is supplied to the coil after the predetermined period in response to the solenoid valve driving signal. A second control signal for generating a second control signal for performing on / off control of the second switching means;
Signal generating means for flowing a flywheel current due to a back electromotive voltage generated in the coil immediately after the predetermined period has passed through the coil via the flywheel diode, and then performing the second switching by the second control signal. In a solenoid valve driving device for supplying an operation holding current to the coil by turning on and off the means, a third switching means provided on a low side of the coil and a level of a current flowing in the coil are detected. And a level of a current detected by the detecting means during the driving of the solenoid valve by the flywheel current in response to the solenoid valve driving signal, the first control signal, and the detecting means. Only when the level is below the third level
Control means for controlling to close the switching means.

According to the present invention, the flywheel is stopped after the supply of the large current to the coil via the first switching means is stopped until the supply of the operation holding current to the coil by the second switching means is started. During the driving period by the wheel current, the third switching means is turned on and off in response to the detection result of the detection means, thereby preventing an excessive current from flowing through the coil. Therefore, the influence of the eddy current generated in the solenoid valve immediately after the first switching means is switched from on to off can be effectively suppressed.

According to a fourth aspect of the present invention, there is provided a high-side switching means provided between a high side of a coil of a solenoid valve and a power supply, a flywheel diode connected to the coil, and a response to a solenoid valve drive signal. A high current is applied to the coil only for a predetermined period immediately after the start of driving of the solenoid valve, and the high side switching means is configured to supply an operation holding current having a level smaller than the large current to the coil after the predetermined period has elapsed. Means for generating a high-side control signal for performing on / off control, wherein a flywheel current due to a back electromotive voltage generated in the coil flows through the coil via the flywheel diode immediately after the predetermined period has elapsed. A low-side switching means provided on the low side of the coil, Detecting means for detecting a level of a current flowing through the coil; and the coil detected by the detecting means in response to the solenoid valve drive signal and the detecting means during the driving of the coil by the flywheel current. And control means for controlling to close the low-side switching means only when the level of the current flowing through the low-side switching means is equal to or lower than a predetermined level.

This invention differs from the invention of claim 3 in that both a large current for initial drive for operating the solenoid valve at high speed and a subsequent operation holding current are supplied to the coil via high-side switching means. ing.

During the drive period by the flywheel current immediately after the supply of the large current to the coil is stopped by the high-side switching means, the low-side switching means is controlled to be turned on and off in response to the detection result of the detection means. It is possible to prevent a current excessively larger than a predetermined level from flowing. Therefore, the influence of the eddy current generated in the solenoid valve immediately after the supply of the large current to the coil is stopped can be effectively suppressed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an electromagnetic valve driving apparatus according to an embodiment of the present invention. An electromagnetic valve driving device 1 shown in FIG. 1 includes an electromagnetic valve 2 used as a fuel injection valve of a vehicle fuel injection device.
For example, includes a 12V battery 3 and a booster circuit 4 which boosts the battery voltage VB of the battery 3 to, for example, 160V and outputs a high voltage output HV.

As shown in FIG. 2, the booster circuit 4 applies a battery voltage VB to the booster coil 4B in accordance with the on / off operation of the booster switching FET element 4A, and outputs a high voltage generated through the diode 4C. Capacitor 4
D has a known configuration.

Returning to FIG. 1, on the high side of the coil 2A of the solenoid valve 2, there is provided a first field effect transistor (FET) 5 for turning on and off the application of the high voltage output HV to the coil 2A of the solenoid valve 2. And a second FET 6 for turning on and off the application of the battery voltage VB to the coil 2A, and a flywheel diode 7. In the present embodiment, a diode 8 is connected in series between the second FET 6 and the coil 2A as shown in FIG.
Is prevented from flowing into the battery 3.

A third FET is provided on the low side of the coil 2A.
9 are provided. In the present embodiment, the third FET 9
Is connected to the low side end of the coil 2A, and the source of the third FET 9 is grounded via the detection resistor 10. A constant voltage diode 11, a diode 12, and a resistor 13 are connected as shown to the gate circuit of the third FET 9, thereby preventing the third FET 9 from being destroyed by the back electromotive force generated in the coil 2A. It has become. When the third FET 9 is turned on,
The solenoid valve drive current IV flowing through the coil 2A also flows through the detection resistor 10 at the same time. Therefore, a detection voltage VD corresponding to the level of the solenoid valve drive current IV flowing through the coil 2A is generated at both ends of the detection resistor 10.

The electromagnetic valve drive signal S that determines the opening period of the electromagnetic valve 2 is input to the first signal generator 15 and the second signal generator 16 after being subjected to noise removal processing by the signal input unit 14.

The solenoid valve drive signal S is a pulse signal which rises at the valve opening start timing TA of the solenoid valve 2 and falls at the valve closing timing TB of the solenoid valve 2 as shown in FIG. The solenoid valve 2 is in the open state during a period during which the solenoid valve drive signal S of the time t to TB is at a high level.

In response to the solenoid valve drive signal S, the first signal generator 15 turns on the first FET 5 only for a predetermined period from the valve opening start timing TA to the drive initial stage end timing TC, thereby sending the high voltage output HV to the coil 2A. This is a circuit that applies a large current to the coil 2A to apply the first control signal C1 (see FIG. 3B) to open the solenoid valve 2 as soon as possible. The first control signal C1 is input to the first drive unit 17, and the first drive unit 17 outputs the first control signal C
When 1 is at a high level, the first FET 5 is turned on.

On the other hand, the second signal generating section 16 responds to the solenoid valve drive signal S from the signal input section 14 and the detection voltage VD, and the detection voltage VD holds the opening operation of the solenoid valve 2 described later. The second FET 6 is turned on and off so that the hold threshold value IH is maintained at the solenoid valve drive current IV when the value falls below the hold threshold value IH which is the level of the solenoid valve drive current IV necessary for the above operation. For outputting a second control signal C2 (see FIG. 3C). The second control signal C2 is input to the second drive unit 18, and the second drive unit 18 turns on the first FET 6 when the second control signal C2 is at a high level.

The third signal generator 19 responds to the solenoid valve drive signal S, the first control signal C1, and the detection voltage VD, and turns on the third FET 9 in the following cases (1) and (2). Control signal C3 is output. (1) When the first FET 5 is turned on. (2) When the solenoid valve drive signal S is at a high level and the solenoid valve drive current IV is smaller than a flywheel threshold IF which is higher than the hold threshold IH. The third control signal C3 is input to the third driving unit 20, and the third driving unit 20 outputs the third signal when the third control signal C3 is at a high level.
ET9 is turned on.

FIG. 4 shows a specific circuit configuration of the second signal generator 16 and the third signal generator 19.

In the third signal generator 19, reference numeral 30 denotes an amplifier circuit comprising an operational amplifier 31 and resistors 32-34, and outputs an amplified detection voltage VA obtained by amplifying the detection voltage VD. 40 is a comparator 41 and resistors 42 to 4
6 and a buffer amplifier 47, and when the level of the amplification detection voltage VA is equal to or higher than the level of the predetermined voltage Vr, the output thereof becomes a low level state. The value of the predetermined voltage Vr is applied to the coil 2A by a solenoid valve driving current I of a level corresponding to the flywheel threshold IF.
It is set equal to the value of the amplification detection voltage VA when V flows. The level of the flywheel threshold IF is shown in FIG. The output of the level discrimination circuit 40 is input to the logic circuit 50.

The logic circuit 50 comprises an AND circuit 51 and an OR circuit 52. One of the input terminals is a solenoid valve drive signal S.
The output of the level discrimination circuit 40 is input to the other input terminal of the AND circuit 51 to which is input. The output of the logic circuit 50 is applied to the other input terminal of the OR circuit 52 to which the first control signal C1 is applied to one input terminal, and the output from the OR circuit 52 is applied to the third control signal C3. Is output as

Accordingly, as shown in FIG. 3D, during the period from TA to TB when the solenoid valve drive signal S is at a high level, the third control signal C3 is at a high level. During the period from TA to TC, which is the level, the level becomes high, and during the period from TC to TB, the solenoid valve driving current I
It goes high only when the level of V is less than the flywheel threshold IF.

The second signal generator 16 includes a comparator 61
And a resistor 62 to 66, and a level discriminating circuit 60 for discriminating the level of the amplified detection voltage VA from the amplifier circuit 30 is provided. The level discrimination circuit 60 includes a comparator 61
And the resistors 62 to 66, and when the level of the amplification detection voltage VA is equal to or higher than the predetermined voltage Vs, the output is in a low level state. The level of the predetermined voltage Vs is
It is set equal to the value of the amplification detection voltage VA when a current having the level of the hold threshold value IH flows through the coil 2A. The output from the level discrimination circuit 60 is input to the other input terminal of the AND circuit 70 in which the electromagnetic valve drive signal S is input to one input terminal, and the output from the AND circuit 70 is the second control signal C2. Is output as Therefore, the level of the second control signal C2 changes as shown in FIG.

Next, the operation of the solenoid valve driving device 1 shown in FIG. 1 will be described with reference to FIG. Timing T
In A, when the level of the solenoid valve drive signal S rises,
A first control signal C1 is output from the first signal generator 15,
The first FET 5 turns on. At the same time, the third control signal C3 output from the third signal
Since the ET is also turned on, the high voltage output HV output from the booster circuit 4 is applied to the coil 2A, and the solenoid valve driving current I
The level of V rises rapidly. As described above, a large current is supplied to the coil 2A in the initial stage of driving the solenoid valve 2,
The valve opening operation of the solenoid valve 2 is performed quickly.

The second control signal C2 becomes high for a short time until the level of the solenoid valve driving current IV exceeds the flywheel threshold IF immediately after the timing TA, and the second FET 6 is turned on. It does not affect the high-speed operation of the solenoid valve 2 by the application of HV.

At timing TB, the first control signal C1
Changes from a high level to a low level, the first FET 5 is turned off, and a large back electromotive voltage is generated in the coil 2A.
Due to this back electromotive voltage, even after the first FET 5 and the second FET 6 are turned off, the flywheel current flows through the coil 2A via the flywheel diode 7 to the solenoid valve drive current I.
It flows as V. Here, on the low side of the coil 2A, a series circuit including the constant voltage diode 11, the diode 12, and the resistor 13 is provided between the ground and the ground, so that the value of the back electromotive force is limited by the constant voltage diode 11. You. The value of the constant voltage diode 11 can be selected to be, for example, 58V, whereby the value of the back electromotive voltage generated at both ends of the coil 2A can be suppressed to a maximum of about 60V.

When the first FET 5 is turned off at the timing TC, an eddy current is generated in the solenoid valve 2 in addition to the back electromotive voltage, whereby the level of the solenoid valve driving current IV is changed to the level shown in FIG. Ascend as shown by the dotted line. Such an increase in the level of the solenoid valve driving current IV due to the eddy current is as follows.
After the initial stage of driving the solenoid valve 2, it is not possible to realize a scheduled operation of passing a predetermined constant level of operation holding current to the coil 2 </ b> A. As a result, the closing timing of the solenoid valve 2 is shorter than the scheduled timing. As a result, the valve opening time of the solenoid valve 2 varies.
When this problem occurs, when the electromagnetic valve 2 is applied to a fuel injection valve for a vehicle, the amount of fuel injection to be supplied to the cylinder varies, and the engine cannot be controlled well.

To prevent this problem from occurring, the detection voltage VD generated at the detection resistor 10 is input to the third signal generator 19, where the solenoid valve driving current I
When the level of V exceeds the flywheel threshold IF, the third FET 9 is turned off. When the solenoid valve drive current IV becomes smaller than the flywheel threshold IF, the third FET 9 is turned off.
A third control signal C3 for performing on / off control of turning on ET9 again is output. As a result, even if an eddy current occurs in the solenoid valve 2 after the timing TC, the level of the solenoid valve drive current IV becomes substantially equal to the flywheel threshold value I.
F.

After the timing TC, when the influence of the back electromotive voltage and the eddy current is reduced, the level of the solenoid valve driving current IV does not exceed the flywheel threshold value IF, so that the third FET 9 is kept on. Then, when the level of the solenoid valve driving current IV gradually decreases and becomes smaller than the hold threshold value IH, the second control signal C2 becomes a high level state, turns on the second FET 6, and the solenoid valve 2 is transferred from the battery 3 to the coil 2A. The solenoid valve drive current IV is supplied to maintain the operation of the solenoid valve. As a result, when the level of the solenoid valve drive current IV rises and becomes equal to or higher than the hold threshold value IH, the second control signal C2 becomes a low level state, the second FET 6 is turned off, and the rise of the solenoid valve drive current IV is suppressed. . As described above, by controlling the second FET 6 to be turned on and off, the level of the solenoid valve drive current IV is maintained at substantially the level of the hold threshold value IH, and the operation holding current is supplied to the coil 2A.

Then, at the timing TB, the level of the solenoid valve drive signal S falls, and thereafter, the second
Both the FET 6 and the third FET 9 are turned off, and the solenoid valve drive current IV rapidly becomes zero.

Since the solenoid valve driving device 1 operates as described above, after the application of the high voltage to the coil 2A in the initial stage of driving of the solenoid valve 2, the coil 2A is scheduled by the eddy current generated in the solenoid valve 2. It is possible to effectively prevent a current larger than the flywheel current from flowing. As a result, the solenoid valve 2 can be stably and accurately controlled to open and close according to the solenoid valve drive signal S. Furthermore, since the solenoid valve driving device 1 is configured to drive the solenoid valve by providing a switch element on each of the high side and the low side of the coil 2A, even if the wiring to the solenoid valve is short-circuited to the ground or the power source, the fuel is not discharged. Problems such as continuous injection can be prevented,
It has an extremely safe and reliable advantage.

Although the present invention has been described with reference to an embodiment, the present invention is limited to a two-power-supply system using a low voltage from a battery voltage and a high voltage from a booster circuit. Instead, the present invention can be similarly applied to a solenoid valve driving device of a type in which the solenoid valve is driven using only a low voltage from the battery voltage.

FIG. 5 is a block diagram showing another embodiment of the solenoid valve driving device according to the present invention. In the solenoid valve driving device 100 shown in FIG.
Reference numeral 2 denotes a high-side FET provided on the high side of the coil 2A of the solenoid valve 2, reference numeral 103 denotes a high-side FET driver for turning on and off the high-side FET 102,
4 is a flywheel diode. A low-side FET 105 is provided on the low side of the coil 2A, and the level of the solenoid valve driving current IV flowing through the coil 2A is detected by a detection voltage VD generated at a detection resistor 106 provided in a source circuit of the low-side FET 105. is there. Constant voltage diode 107, diode 108 and resistor 1 connected to low side FET 105
Reference numeral 09 is provided for the same purpose as the constant voltage diode 11, the diode 12, and the resistor 13 connected to the third FET 9 in FIG. Reference numeral 110 denotes a low-side FET driving unit for driving the low-side FET on and off.

The signal input section 14 and the first signal generation section 15 are the same as those shown in FIG. High side FET
The control unit 111 responds to the output from the signal input unit 14, the first control signal C1, and the detection voltage VD, and
It outputs a T control signal CH. On the other hand, the low-side FET control unit 112 responds to the solenoid valve drive signal S, the first control signal C1, and the detection voltage VD, and controls the low-side FET 105 to turn on and off the low-side FET 105.
Is output.

FIG. 6 shows a waveform diagram of the signals of the respective parts shown in FIG.

FIG. 6A shows the waveform of the solenoid valve drive signal S, which is the same as that described with reference to FIG.

FIG. 6B is a waveform diagram of the high-side FET control signal CH. The high-side FET control signal CH is at a high level during the timing TA to TC according to the first control signal C1, and the level of the solenoid valve drive current IV is held. When the threshold value IH is lower than the threshold value IH, the level becomes a high level, the high-side FET 102 is turned on, and a required operation holding current can flow through the coil 2A. As can be understood from the above description, the high-side FET control unit 111 has each function of the first signal generation unit 15 and the second drive unit 18 of FIG.

FIG. 6C is a waveform diagram of the low-side FET control signal CL. This waveform diagram is the same as that shown in FIG.
Performs a function similar to that of the third signal generator 19 in FIG.

Since the solenoid valve driving device 100 is configured as described above, as can be seen from the waveform of the solenoid valve driving current IV shown in FIG. And the low-side FET 102, 1
05 are both turned on and a large current is supplied to the coil 2A, whereby the solenoid valve 2 can be opened in a short time. At timing TC, the high side and low side F
The ETs 102 and 105 are both turned off, and a flywheel current flows through the coil 2A due to the back electromotive voltage generated at the coil 2A. In this driving state, the low-side FET 105 is turned on in accordance with the low-side FET control signal CL so that the electromagnetic valve driving current IV does not exceed the flywheel threshold IF, as in the case of the electromagnetic valve driving device 1 of FIG. Is turned off. As a result, regardless of the presence of the eddy current generated in the solenoid valve 2, an excessive increase in the level of the solenoid valve drive current IV can be suppressed in the same manner as in the case of the apparatus of FIG.

Then, when the level of the solenoid valve driving current IV decreases and becomes smaller than the flywheel threshold value IF,
High side FE by high side FET control signal CH
T102 is turned on and off to supply a required operation holding current from the battery 101 to the coil 2A.

[0046]

According to the present invention, as described above, the solenoid valve is opened or closed at a high speed by applying a large current to the coil at the initial stage of driving the solenoid valve, and then the solenoid valve is opened. Interrupting the current supply, thereby causing a flywheel current to flow through the solenoid valve coil by the back electromotive force generated in the solenoid valve coil,
When the solenoid valve is driven by supplying the holding current from the power supply to the solenoid valve coil when the level of the flywheel current becomes smaller than the required operation holding current level, the level of the current flowing through the solenoid valve coil is reduced. Detecting and turning on / off a switching means provided on the low side of the solenoid valve coil so that the current does not exceed a predetermined level of the flywheel current after interrupting the current to the solenoid valve coil in the initial drive stage. Therefore, it is possible to effectively suppress an excessive increase in the solenoid valve driving current due to the influence of the eddy current generated after the current to the solenoid valve coil is cut off in the initial stage of driving, and to stably and accurately drive the solenoid valve. Further, according to the present invention, the solenoid valve drive current is turned on and off on the high side and low side of the coil of the solenoid valve,
Since the solenoid valve is driven by providing a switch element for controlling the off, there is no danger that the open / close state of the solenoid valve falls into an unintended state even if the wiring to the solenoid valve is shorted to the ground or the power supply. It has an extremely safe and reliable advantage.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a solenoid valve driving device according to the present invention.

FIG. 2 is a detailed circuit diagram of the booster circuit of FIG. 1;

FIG. 3 is a waveform chart for explaining the operation of the solenoid valve driving device of FIG. 1;

FIG. 4 is a detailed circuit diagram of a second signal generator and a third signal generator of FIG. 1;

FIG. 5 is a block diagram showing another embodiment of the solenoid valve driving device according to the present invention.

FIG. 6 is a waveform chart for explaining the operation of the solenoid valve driving device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 100 Solenoid valve drive device 2 Solenoid valve 2A Coil 3 Battery 5 First FET 6 Second FET 7, 104 Flywheel diode 9 Third FET 10, 106 Detection resistor 15 First signal generator 16 Second signal generator 19 Third Signal generator 102 High-side FET 105 Low-side FET 111 High-side FET controller 112 Low-side FET controller C1 First control signal C2 Second control signal C3 Third control signal CH High-side FET control signal CL Low-side FET control signal DV Detection voltage HV High voltage output IF Flywheel threshold IH Hold threshold IV Solenoid valve drive current S Solenoid valve drive signal VB Battery voltage

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 31/06 F02D 41/20 325

Claims (4)

(57) [Claims] A large current is applied to the solenoid valve coil for a predetermined period immediately after the start of driving of the solenoid valve, and after a lapse of the predetermined period,
After flowing the flywheel current as an operation holding current to the coil using a back electromotive voltage generated in the coil by cutting off the large current flowing in the coil, the flywheel current is smaller than the large current for a required period of time in the coil. In a solenoid valve driving method in which a predetermined operation holding current is supplied from a power supply, an energization control unit is provided on a low side of the coil, and during a driving period of the coil by the flywheel current, a level of a current flowing through the coil is controlled. An electromagnetic valve driving method, wherein an excessive increase in the flywheel current is suppressed by turning on the energization control means only when a detected level is equal to or lower than a predetermined level in response to a detection result. . 2. A first and a second switching means and a flywheel diode connected to the coil are provided on the high side of a coil of the solenoid valve, and the first switching means is provided only for a predetermined period after the start of driving of the solenoid valve. A large current flows from the power supply unit to the coil by closing the flywheel, and after the predetermined period elapses, a flywheel current due to a back electromotive voltage generated in the coil flows through the coil via the flywheel diode, and the flywheel current is When the current drops below the level of a predetermined operation holding current smaller than the large current, an electromagnetic operation is performed such that a predetermined operation holding current flows from the power supply unit to the coil by turning on and off the second switching means for a required period. In the valve driving method, a third switching means is provided on a low side of the coil, and the flywheel is provided. An electromagnetic valve which suppresses an excessive rise of the flywheel current by closing the third switching means only when the flywheel current is lower than a predetermined level during a period in which the coil is driven by a current. Drive method. A first switching means and a second switching means provided between a high side of a coil of the solenoid valve and a power supply, a flywheel diode connected to the coil, and a response to a solenoid valve driving signal. A first signal generating means for generating a first control signal for performing on / off control of the first switching means so that a large current flows through the coil for a predetermined period immediately after the start of driving of the electromagnetic valve; Generating a second control signal for performing on / off control of the second switching means so as to flow an operation holding current having a level smaller than the large current to the coil after the predetermined period in response to the valve drive signal; And a flywheel current generated by the back electromotive force generated in the coil immediately after the predetermined period has passed through the flywheel diode. An electromagnetic valve driving device configured to supply an operation holding current to the coil by turning on and off the second switching means according to the second control signal after flowing the current through the coil; provided on a low side of the coil; Third switching means, detection means for detecting the level of current flowing through the coil, and the solenoid valve based on the flywheel current in response to the solenoid valve drive signal, the first control signal, and the detection means Control means for controlling the third switching means to close only when the level of the current detected by the detection means is equal to or lower than a predetermined level during the driving period. 4. A high-side switching means provided between a high side of a coil of a solenoid valve and a power supply unit, a flywheel diode connected to the coil, and a solenoid valve of the solenoid valve responsive to a solenoid valve driving signal. A high current is supplied to the coil only for a predetermined period immediately after the start of driving, and an ON / OFF control of the high side switching means is performed so that an operation holding current of a level smaller than the large current is supplied to the coil after the predetermined period. Means for generating a high-side control signal to be performed, wherein an electromagnetic valve drive is configured to cause a flywheel current due to a back electromotive voltage generated in the coil to flow through the coil via the flywheel diode immediately after the predetermined period has elapsed. In the apparatus, a low-side switching means provided on a low side of the coil; Detecting means for detecting a level of a current; and a current flowing through the coil detected by the detecting means during a driving period of the coil by the flywheel current in response to the solenoid valve drive signal and the detecting means. Control means for controlling the low-side switching means to close only when the level is equal to or lower than a predetermined level.