JP2000028027A - Solenoid valve driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce electric power consumption by preventing the loss of booster voltage generated from a booster circuit. SOLUTION: In a case where driving of a solenoid valve SV1 is stopped for a predetermined time or more to lower control voltage VCP of a capacitor, the solenoid valve SV1 is pre-driven for a predetermined time width W1 by a pre-drive pulse set to be short for preventing the solenoid valve SV1 from operating before a first driving. The capacitor is charged upto a predetermined level by back electromotive force generated from a solenoid coil 21 of the solenoid valve 1. Then, the solenoid valve SV1 is driven by a normal drive pulse at predetermined timing. Accordingly, a field effect transistor on high side can be turned on by the control voltage VCP at a predetermined level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve driving method in which a solenoid valve is driven by using a high side switch element.

[0002]

2. Description of the Related Art When a solenoid valve is driven, a drive circuit connects a semiconductor switching element or the like in series with the solenoid valve, and controls the semiconductor switching element to be turned on and off by an external control signal. In general, the configuration is such that the exciting current to the motor is controlled. Such a switching element is usually arranged on the low side of the solenoid valve in many cases. However, when driving a solenoid valve used in an automobile or the like, there is an increasing demand for driving the solenoid valve with a high-side switch from the viewpoint of safety. The reason is that in automobiles, etc., the body is connected to the negative terminal of the battery, so even if the drive line short-circuits with the body, a system in which a solenoid valve is placed on the ground side as seen from the switch (high-side switch system) This is because the solenoid valve is safe because it is not accidentally energized.

If the switch provided on the high side of the solenoid valve is constituted by an NPN transistor, wasteful power is consumed, heat is generated, and the minimum operating voltage of the solenoid valve is increased by several volts. This causes a problem. As the high-side switch, an N-channel field effect transistor (FET) may be used, but the same problem occurs. Therefore, in order to efficiently use an N-channel FET or an NPN transistor as a high-side switch element, it is necessary to generate a voltage higher than the solenoid valve driving voltage.

To solve this problem, Japanese Patent Laid-Open No. 10-2
Japanese Patent No. 6245 has a booster circuit for boosting a DC voltage from a DC power supply to obtain a high voltage, a field effect transistor for controlling application of the high voltage to a solenoid coil of an electromagnetic valve, and a capacitor. There is disclosed a configuration in which a DC power supply and a booster circuit charge a capacitor with a control high voltage for on / off control of a field effect transistor and apply the voltage to a gate electrode of the field effect transistor at a required timing. ing.

According to this configuration, when the power supply of the device is turned on, a charging current flows from both the DC power supply and the boosting circuit to the capacitor. However, when the charging current of the capacitor becomes substantially equal to the voltage of the DC power supply, the capacitor is switched from the DC power supply. The charging current stops flowing to the capacitor, and the charging current to the capacitor is only supplied from the booster circuit. In this way, the capacitor is charged to the high voltage level.

[0006]

The above-described conventional configuration has a problem that the load of the booster circuit increases because the charging current flows from the booster circuit to the capacitor even when the solenoid valve is not driven. ing. That is, the booster circuit is used to supply a large current to the solenoid valve in order to enable high-speed operation in the initial stage of driving the solenoid valve, and it is desirable that the booster circuit always store a high voltage. Instead, in the above-described conventional configuration, a current always flows from the booster circuit to the capacitor, and the charge of the capacitor in the booster circuit is reduced.

An object of the present invention is to provide a solenoid valve driving method capable of solving the above-mentioned problems in the prior art.

[0008]

According to the present invention, when the operation of the solenoid valve is stopped for a predetermined time or more, the solenoid valve is set for a short predetermined time width so that the solenoid valve does not operate before the first driving thereafter. By driving the solenoid valve properly at a predetermined timing thereafter, waste of the boosted voltage generated in the booster circuit can be prevented, and power consumption can be reduced.

According to the first aspect of the present invention, a semiconductor switching element is provided on the high side of the solenoid valve, and a capacitor which is charged by a back electromotive force generated in a coil of the solenoid valve or a DC output from a DC power supply is provided. In the solenoid valve driving method in which the semiconductor switching element is controlled to be turned on and off by using the charge stored in the capacitor, when the non-drive state of the solenoid valve continues for a predetermined time or more, the first normal drive after that Prior to this, a configuration is proposed in which the solenoid valve is driven for a predetermined short time width so that the solenoid valve does not operate, and then the solenoid valve is normally driven at a predetermined timing.

According to the second aspect of the present invention, a semiconductor switching element is provided on the high side of the solenoid valve, and a capacitor which is charged by a back electromotive force generated in a coil of the solenoid valve or a DC output from a DC power source is provided. In the solenoid valve driving method in which the semiconductor switching element is controlled to be turned on and off by using electric charge stored in a capacitor, the solenoid valve operates before the first normal driving of the solenoid valve after power is turned on. There is proposed a configuration in which the solenoid valve is driven for a predetermined short time width set shortly so that the solenoid valve is normally driven at a predetermined timing.

When electric energy is applied to the solenoid valve for a time period during which the solenoid valve does not operate prior to normal driving, the solenoid valve does not operate but a back electromotive force is generated in the solenoid coil of the solenoid valve. For this reason, even if the charging voltage of the capacitor is reduced due to the suspension of the solenoid valve for a predetermined time or more, the capacitor can be charged to the predetermined level by the back electromotive force. For this reason, the semiconductor switching element provided on the high side of the solenoid valve can be reliably used by using the electric energy charged in the capacitor in the case of normal driving immediately thereafter without receiving the supply of energy from the booster circuit. Can be activated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of a fuel injection system for an internal combustion engine, which is configured to drive an electromagnetic valve of an injector device for injecting fuel into each cylinder of the internal combustion engine by the electromagnetic valve driving method according to the present invention. It is a schematic structure figure showing an example of form.

In FIG. 1, a fuel injection control device 1 responds to a vehicle signal S indicating an accelerator opening, an engine speed, a cooling water temperature, an intake air amount, and the like.
This is a device for controlling fuel injection timing, fuel injection amount, ignition timing, and the like to C4, and is configured by a microcomputer system having a known configuration. The fuel injection control device 1 outputs injection control signals A1 to A4 for fuel injection control for each of the cylinders C1 to C4. The drive unit 3 includes injection control signals A1 to A4
, The solenoid valves SV1 to SV4 of the injector devices J1 to J4 provided corresponding to the cylinders C1 to C4, respectively.
The solenoid valves SV1 to SV4 are controlled to open and close in response to the drive signals D1 to D4, respectively, so that a required amount of fuel is supplied to each of the cylinders C1 to C4 at a required timing. Is injected.

FIG. 2 shows only a circuit portion of the drive unit 3 necessary for driving the solenoid valve SV1 in detail. The circuit shown in FIG. 2 applies a high voltage to the solenoid coil 21 of the solenoid valve SV1 in the initial stage of driving to quickly operate the solenoid valve SV1, and thereafter,
The circuit configuration is such that a constant current drive control for flowing a predetermined constant current through the solenoid coil 21 to maintain the operation of the solenoid valve SV1 is performed. In FIG. 2, reference numeral 22 denotes a DC power supply for supplying a DC voltage VB, and reference numeral 23 denotes a booster circuit having a known circuit configuration for boosting the DC voltage VB and outputting a high voltage VP of about 160 V.

Reference numeral 24 denotes a high voltage VP from the booster circuit 23.
Is an N-channel type field effect transistor (FET) provided on the high side opposite to the ground side of the solenoid valve SV1 as a semiconductor switching element for applying the voltage to the solenoid coil 21 of the solenoid valve SV1, the source of which is a solenoid. The drain of the coil 21 is connected to the output of the booster circuit 23. The solenoid coil 21 has a constant voltage diode 25
And a series circuit of a diode 26 are connected in parallel, and the low side terminal of the solenoid coil 21 is directly grounded.

Reference numeral 27 denotes a constant current drive control unit having a known configuration for driving the solenoid valve SV1 at a constant current. The constant current drive control unit 27 includes a switching transistor 28, a current detection resistor 29, and a diode 30, which are connected in series between the DC power supply 22 and the high side terminal of the solenoid coil 21 of the solenoid valve SV1 as shown in the figure. Then, a detection voltage generated at both ends of the current detection resistor 29 is input to the constant current circuit 31, and the switching transistor 28 is driven by the constant current circuit 31 so that the solenoid valve SV1 is driven at a constant current.
On and off. The control for the constant current driving described above is executed only during a period in which the drive control signal DS applied to the control terminal 31A of the constant current circuit 31 and constituting a part of the injection control signal A1 is at a high level. .

Prior to the constant current drive by the constant current drive controller 27, the solenoid valve SV1 is set to the high voltage V
A switching element driving circuit 32 is provided to output a control voltage VCP for turning on the N-channel field effect transistor 24 for the above-mentioned predetermined period in order to operate at high speed by P.

FIG. 3 shows a switching element driving circuit 32.
The detailed circuit diagram of FIG. The switching element drive circuit 32 includes a capacitor 41, and a voltage storage circuit 40 for charging the capacitor 41 with a control voltage VCP for controlling ON / OFF of the N-channel type field effect transistor 24 by the DC power supply 22. , The control voltage VC
A switching circuit 50 for applying P to the gate electrode of the N-channel type field effect transistor 24 at a required timing.

First, the voltage storage circuit 40 will be described. Reference numeral 42 denotes a constant voltage diode connected in parallel with the capacitor 41, and the constant voltage diode 42 suppresses the charging voltage of the capacitor 41 to the Zener voltage or less. The diode 43 and the resistor 46 form a charging path for flowing a charging current from the DC power supply 22 to the capacitor 41.

The switching circuit 50 applies the control voltage VCP between the gate and source of the N-channel type field effect transistor 24 only while the control signal HS applied to the control input terminal 50A is at a high level. And switching circuits 51 and 52 and resistors 53 to 56 are connected as shown in the figure.

Since the circuit for driving the solenoid valve SV1 is configured as described above, the charging voltage of the capacitor 41 is zero volt immediately after the power supply of the drive unit 3 is turned on. Then, the capacitor 41 is charged by a charging current flowing through a charging path including the diode 43 and the resistor 46. At this time, the field effect transistor 24 is off. The above-described charging operation is performed by controlling the control voltage VCP which is the charging voltage of the capacitor 41.
Until a voltage obtained by subtracting a voltage drop in the diode 43 from the DC voltage VB.

As described above, before the solenoid valve SV1 is driven, the charging current flows to the capacitor 41 through the solenoid coil 21 of the solenoid valve SV1, and charges the capacitor 41. The capacitor 41 is also charged by the back electromotive force generated in the solenoid coil 21 when the solenoid valve SV1 is driven. In this case, the capacitor 41 is charged to a higher voltage than the DC voltage VB. The value of the resistor 46 is appropriately determined so that the solenoid valve SV does not operate when the charging current flows through the solenoid coil 21. Note that the control signal HS is also a signal for control constituting a part of the injection control signal A1.

Although the circuit configuration for driving the solenoid valve SV1 has been described above, the other solenoid valves SV2 to SV4 are similarly driven using the same circuit configuration.

Next, by the circuits shown in FIGS. 2 and 3,
The fuel injection control device 1 configured to control the solenoid valve SV1 by the method of the present invention will be described in detail.

Prior to the detailed description, the fuel injection control device 1
The driving method of the solenoid valve SV1 is described below. This driving method is used when the injector is driven first after a key switch (not shown) is turned on, or when the accelerator pedal is released during running of the vehicle and the fuel cut is long. In the case of injector driving after a state in which the injector is not driven for a predetermined time or more for a certain time, for example, the injection control signal A1
Control signal HS and drive control signal DS constituting
Prior to the regular driving by the solenoid valve, a pre-driving pulse for driving the solenoid valve SV1 for a predetermined time width set to a short time length such that the solenoid valve SV1 does not operate is output, thereby SV1 solenoid coil 21
By charging the capacitor 41 with the back electromotive force generated in the step (a), the level of the control voltage VCP is set to a level sufficient to drive the field effect transistor 24, and the control signal HS
The field effect transistor 24 controls the control voltage VCP when the solenoid valve SV1 is normally driven by the drive control signal DS.
It is designed to operate reliably by utilizing the above.

FIGS. 4 and 5 are flowcharts showing a program for controlling the operation of the solenoid valve, which is executed in the fuel injection control device 1 constructed as a computer system.

The main routine 100 shown in FIG. 4 is started at regular intervals (for example, every 10 msec). When the main routine 100 is started, first, in step S1, the injection time in the injector J1 is calculated based on the vehicle signal S. Next, in step S2, it is determined whether or not the injection time calculated in step S1 is zero, that is, whether or not there is no injection. When it is determined that the injection time calculated in step S1 is zero, that is, no injection is performed, the determination result in step S2 is YES, and the process proceeds to step S3.

In step S3, it is determined whether or not the value of the no-injection counter is larger than a predetermined value K1. In the initialization at power-on, the value of the no-injection counter is a predetermined value K
Initialized to 1. The non-injection counter value is a predetermined value K1
If the value is larger than the predetermined value, the determination result of step S3 is YES, and the process of the main routine 100 ends as it is. If the no-injection counter value is smaller than the predetermined value K1, the determination result in step S3 is NO. In step S4, 1 is added to the no-injection counter value.
Is completed.

On the other hand, in step S2, step S
If it is determined that the injection time calculated in step 1 is not zero, that is, it is not non-injection, the determination result of step S2 is N
It becomes O and it enters into step S5. Here, when it is determined that there is no injection, it means that injection is necessary. In step S5, it is determined whether or not the no-injection counter value is greater than a predetermined value K2, and it is determined whether or not the capacitor 41 (FIG. 3) needs to be charged.

If it is determined in step S5 that the no-injection counter value is larger than the predetermined value K2, the result of the determination in step S5 is YES, and the process proceeds to step S6. When the non-injection counter value is larger than the predetermined value K2, it is determined that the capacitor 41 needs to be charged because the non-injection time has continued for the predetermined time or more, and the pre-drive flag for performing the pre-drive of the injector device J1 is determined in step S6. It is turned ON.

Next, at step S7, the injector J
A pre-injection timing and a pre-injection time for the pre-driving are set. The pre-injection time is set to a short time so that the solenoid valve SV1 does not actually operate. Further, in step S8, the injection timing and injection time for normal driving of the injector J1 are set, and then, in step S9, the no-injection counter value is cleared, and the processing of the main routine 100 ends.

On the other hand, if it is determined in step S5 that the no-injection counter value is smaller than the predetermined value K2, it is determined that pre-driving for charging the capacitor 41 is unnecessary, and the determination result in step S5 is NO. It enters step S10. In step S10, it is determined whether or not the pre-drive flag is ON. If the pre-drive flag is ON, the result of the determination in step S10 is YES, and the processing of the main routine 100 ends. If the pre-drive flag has not been turned ON, the determination result of step S10 is NO, and steps S8 and S9 are executed.

As described above, the main routine 10
If it is 0, it is determined whether or not the fuel-injection state of the injector device J1 has continued for a time required to charge the capacitor 41 (step S5). When the non-injection counter value becomes larger than the predetermined value K2, it is determined that the pre-driving of the solenoid valve SV1 is necessary to charge the capacitor 41, and the pre-driving flag is turned on (step S).
6), pre-injection timing and pre-injection time are set (step S7).

Next, the setting operation of the falling edge of the injection pulse will be described with reference to FIGS.

FIG. 5 shows a crank angle 20 ° interrupt processing 20
6 is a flowchart showing 0. When entering the crank angle 20 ° interrupt processing 200, it is determined in step S21 whether or not the crank angle is 700 °. Crank angle is 70
If it is determined that it is not 0 °, the determination result of step S21 is NO, and the crank angle is set to 2 in step S22.
The value obtained by adding 0 ° is set as the crank angle in the next step S24.
to go into. On the other hand, in step S21, the crank angle is 700 °.
Is determined to be YES, the determination result of step S21 is YES, and the crank angle is set to 0 ° in step S23.
And enters the next step S24. That is, the crank angle at that time is set.

In step S24, it is determined whether or not injection is not performed. If it is determined that there is no injection, it is not necessary to set the fall of the injection pulse, so the determination result in step S24 is YES, and the crank angle 20 ° interrupt processing 200 ends. If it is determined in step S24 that the fuel is not injected, the determination result in step S24 is NO, and the process proceeds to step S25.

In step S25, the pre-drive flag is turned on.
Is determined. Pre-drive flag is O
If N has not been reached, the decision result in the step S25 is NO, and the process proceeds to a step S26.

In step S26, it is determined whether or not the difference obtained by subtracting the crank angle from the injection start timing is smaller than a predetermined value K3. If it is determined that the difference obtained by subtracting the crank angle from the injection start timing is equal to or larger than the predetermined value K3, the process proceeds to step S
26 is NO, and the crank angle 20
° The interrupt processing 200 ends. When it is determined that the difference obtained by subtracting the crank angle from the injection start timing is smaller than the predetermined value K3, the determination result of step S26 is YES, and the process proceeds to step S27.

In step S27, a delay time is set in the output compare, and thereafter, in step S28, the output compare interrupt is permitted, and the crank angle 20
° The interrupt processing 200 ends. That is, step S
The end of the pre-injection is set at the crank angle timing when the condition 26 becomes YES.

On the other hand, in step S25, the pre-drive flag is ON, and the result of determination in step S25 is YE
When S is reached, the process proceeds to step S29. In step S29, it is determined whether or not the difference obtained by subtracting the crank angle from the pre-injection timing is smaller than a predetermined value K3. If it is determined that the difference obtained by subtracting the crank angle from the pre-injection timing is equal to or larger than the predetermined value K3, the determination result in step S29 is NO, and the crank angle 20 ° interrupt processing 200 ends. If it is determined that the difference obtained by subtracting the crank angle from the pre-injection timing is smaller than the predetermined value K3, the determination result of step S29 is Y
ES is set, and a delay time is set in the output compare in step S30. Then, an output compare interrupt is permitted in step S31, and the crank angle 20 ° interrupt processing 200 ends.

At the same time as the falling of the injection pulse, an output compare interrupt occurs, and the output compare interrupt processing 300 shown in FIG. 6 is started. Also in the output compare interrupt processing 300, step S4
At 1, it is determined whether or not the pre-drive flag is ON. If the pre-drive flag is not ON, the determination result in the step S41 is NO, the injection time is set in the output compare in a step S42, and the output compare interrupt processing 300 ends.

If the pre-drive flag is ON in step S41, the decision result in step S41 is YES.
In step S43, a time corresponding to the pre-injection time is set in the output compare. Thereafter, the pre-drive flag is turned off in step S44, and the output compare interrupt processing 300 ends, and the normal injection operation is executed according to the setting in step S8.

The setting of the pre-driving pulse P1 and the normal driving pulse P2 according to the processing shown in FIGS. 5 and 6 will be described with reference to FIG.

FIG. 7A shows a main routine 1.
00 shows a start timing of 00, and (B) shows a TDC pulse waveform. (C) shows the waveform of the crank 20 ° pulse, and (D) shows the waveform of the injection pulse based on the drive signal D1.

When the pre-injection flag is ON, the pre-injection timing t1 set in step S7 is compared with the current crank angle. If it is necessary to set the output compare in the current interrupt based on this comparison signal, the delay time is set in the output compare register, thereby setting the falling timing t2 of the pre-driving pulse P1. As a result, the pre-driving pulse P1 is changed from t1 to t.
2 during the “L” level, and during this time the solenoid valve SV
1 is driven. However, since this time width (delay time) W1 is set to a short time such that the solenoid valve SV1 does not actually operate, a predetermined high voltage is applied to the capacitor 41 by applying the pre-drive pulse P1 to the solenoid valve SV1. Is only charged.

Thereafter, only during the period from t3 to t4, the solenoid valve SV
A normal drive pulse P2 having a time width W2 for actually driving the pulse No. 1 is output. As a result, at t3, since the capacitor 41 is charged to a level sufficient to turn on the field effect transistor 24 by the pre-drive pulse P1, even if the downtime of the injector device J1 is long, the booster circuit The field effect transistor 24 can be reliably operated without any use of the output of the transistor 23.

Although only the driving of the injector J1 has been described above, the driving of the other injectors J1 to J4 is performed in exactly the same manner.

[0049]

According to the present invention, as described above, the capacitor is charged with a predetermined high voltage by the back electromotive force generated by driving the solenoid valve for such a short time that the solenoid valve does not actually operate. After that, the solenoid valve is actually driven, so even if the non-drive state of the solenoid valve is prolonged and the charging voltage of the capacitor is reduced, the semiconductor switching element can be used without any use of the output of the booster circuit. Can be reliably operated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an embodiment of the present invention.

FIG. 2 is a partial detailed circuit diagram of the drive unit shown in FIG.

FIG. 3 is a detailed circuit diagram of the switching element driving circuit shown in FIG. 2;

FIG. 4 is a flowchart showing a main routine process for drive control of an electromagnetic valve in the fuel injection control device of FIG. 1;

5 is a flowchart showing a crank angle 20 ° interrupt process for drive control of an electromagnetic valve in the fuel injection control device of FIG. 1;

6 is a flowchart showing an output compare interrupt process for driving control of an electromagnetic valve in the fuel injection control device of FIG. 1;

FIG. 7 is an explanatory diagram for explaining setting of a pre-injection pulse and a normal injection pulse in the fuel injection control device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection control apparatus 2 Internal combustion engine 3 Drive unit 21 Solenoid coil 22 DC power supply 23 Boost circuit 24 Field effect transistor (FET) 27 Constant current drive control unit 28 Switching transistor 40 Voltage storage circuit 41 Capacitors A1 to A4 Injection control signal C1 C4 cylinder D1 to D4 drive signal DS drive control signal HS control signal J1 to J4 injector device P1 pre-drive pulse P2 regular drive pulse S vehicle signal SV1 to SV4 solenoid valve VB DC voltage VCP control voltage VP high voltage

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H02M 3/155 H02M 3/155 H (72) Inventor Toshiyuki Yoshino 3-13-26 Yayumicho, Higashimatsuyama-shi, Saitama Stock Company 3G066 BA00 BA17 CD26 CD28 CE25 CE29 DC00 DC04 DC09 DC11 DC14 3H106 FA01 KK18 5H430 BB01 BB09 BB12 BB20 EE06 EE07 FF08 FF13 LA04 LB06 5H730 AS04 BB14 BB57 BB82 96

Claims (2)

[Claims] 1. A semiconductor switching element is provided on the high side of a solenoid valve, and a capacitor is charged by a back electromotive force generated in a coil of the solenoid valve or a DC output from a DC power supply, and a charge stored in the capacitor is used. And the semiconductor switching element is turned on and off, in the solenoid valve driving method, wherein when the non-drive state of the solenoid valve continues for a predetermined time or more,
Prior to the first normal drive thereafter, the solenoid valve is driven for a predetermined short time width set so that the solenoid valve does not operate, and then the solenoid valve is normally driven at a predetermined timing. A method for driving a solenoid valve, comprising: 2. A semiconductor switching element is provided on the high side of the solenoid valve, and a capacitor charged by a back electromotive force generated in a coil of the solenoid valve or a DC output from a DC power supply is used, and electric charge stored in the capacitor is used. In the solenoid valve driving method in which the semiconductor switching element is controlled to be turned on and off, prior to the first normal driving of the solenoid valve after power is turned on, the solenoid valve is set to be short so as not to operate. A method of driving an electromagnetic valve, characterized in that the electromagnetic valve is driven for a predetermined time width, and thereafter the electromagnetic valve is normally driven at a predetermined timing.