JP2002237411A - Solenoid valve drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solenoid valve drive which can improve the drive responsiveness of a solenoid valve, can reduce the power consumption of the valve and the size of a switching element at a high level. SOLUTION: This solenoid valve drive turns on a current feeding MOSFET at the starting timing of a current feeing period to the coil of the solenoid valve and, when the current I fed to the coil exceeds a first controlled current value Ip, turns off the MOSFET. Thereafter, the drive controls the current I to the controlled current value Ip or its vicinity by turning on the MOSFET by a first turning-on period of time T1 whenever the drive discriminates that the current I decreases to the value Ip until a prescribed period of time Tp elapses after the current feeding period is started. Until the current feeding period ends after the prescribed period of time Tp has elapsed, the drive controls the current I to a second controlled current value Ih which is smaller than the first value Ip or its vicinity by turning on the MOSFET by a second turning-on period of time T2 which is shorter than the first period of time T1 whenever the drive discriminates that the current I decreases to the value Ih.

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 device.

[0002]

2. Description of the Related Art Conventionally, as a drive device of an electromagnetic valve used for supplying fuel to a vehicle engine, for example,
As described in Japanese Patent Publication No. 4-42805,
During a period from the start of energization to the coil of the solenoid valve until a predetermined time elapses, the energizing current flowing through the coil of the solenoid valve changes the operating position when energizing the valve body of the solenoid valve to the coil (hereinafter, energizing operation position) The valve is quickly operated by controlling the current value to a predetermined value for operating the valve element, which can be moved to a predetermined value. By controlling so as to be a predetermined holding current value that can be held at a predetermined value and is smaller than the valve operating current value, the drive responsiveness of the solenoid valve (operating responsiveness of the valve body) and reduction of the energizing current (extended And lower power consumption).

Here, in order to further clarify such a driving technique, for example, a configuration example of a driving device of an electromagnetic valve used for a high-pressure fuel pump for increasing the pressure of fuel supplied to a direct injection engine for a vehicle will be described. First, as shown in FIG. 4, in the control system of the direct injection engine, the fuel tank 1
Is pumped by a low-pressure pump 2 to a high-pressure fuel pump 3, where the pressure is raised to a predetermined pressure by the high-pressure fuel pump 3, and then supplied to an injector (electromagnetic fuel injection valve) 4. And the injector 4
Fuel is directly injected into the combustion chamber 5 of the engine.

As shown in FIG. 5, the high-pressure fuel pump 3 has a solenoid valve 6, a piston 8 which moves up and down in accordance with the rotation of a camshaft 7 of the engine, and a volume which increases and decreases as the piston 8 moves up and down. And a fuel chamber 9 communicating with a fuel supply path 10 to the injector 4.

In this example, when the coil L is not energized, the valve 6a is connected to the return spring 6b.
Supply path 11 from the low pressure pump 2 by the urging force of
Is moved to a valve opening position for communicating the fuel cell 9 and the fuel chamber 9, and the coil L
The valve body 6a is of a normally open type in which the valve body 6a moves to a closed position where the fuel supply path 11 and the fuel chamber 9 are shut off against the urging force of the return spring 6b when the power is supplied to the valve.

In the high-pressure fuel pump 3, when the fuel from the low-pressure pump 2 is sent to the fuel chamber 9 (ie, when the piston 8 descends), the coil L of the solenoid valve 6 is de-energized. The solenoid valve 6 opens (the valve body 6a moves to the valve opening position), and the pressure in the fuel chamber 9 is increased to increase the pressure in the fuel chamber 9.
When the fuel inside is discharged to the injector 4 (that is, when the piston 8 rises), the coil L of the solenoid valve 6 is energized and the solenoid valve 6 is closed (the valve body 6a is in the closed position). Moving).

The power supply period to the coil L of the solenoid valve 6 (that is, power supply start timing and power supply continuation time)
The electronic control unit 13 as an electromagnetic valve driving device that operates by receiving the power of a battery 12 mounted on the vehicle is controlled in synchronization with the rotation of the camshaft 7 and the crankshaft of the engine.

Next, as shown in FIG. 6, an electronic control unit 13 for controlling the solenoid valve 6 is provided in series with a current path for flowing a current from the battery 12 to the coil L of the solenoid valve 6. When turned on, a P-channel MOSFET 2 serving as a switching element for driving the solenoid valve 6 by driving a current I to the coil L (valve closing drive in this example)
1 and a crankshaft rotation signal output from the crankshaft rotation sensor of the engine according to the rotation angle of the crankshaft and a camshaft rotation signal output from the camshaft rotation sensor according to the rotation angle of the camshaft 7. A microcomputer (hereinafter, referred to as a microcomputer) 23 that sets an energization period to the coil L by calculation and outputs a high-level drive signal SD for turning on the MOSFET 21 during the set energization period. Have.

In this example, a so-called high-side switching type in which the MOSFET 21 is arranged on the upstream side of the coil L is employed. That is, the source of the MOSFET 21 is connected to the plus terminal of the battery 12 and its MO
The drain of the SFET 21 is connected to one end of the coil L. A MOS is provided between the drain of the MOSFET 21 and the ground (negative terminal side of the battery 12).
A diode 25 is connected to circulate the energy remaining in the coil L when the FET 21 is turned off.

The electronic control unit 13 includes a current detecting resistor 31 connected between the ground and an end of the coil L on the side opposite to the MOSFET 21 side, and a voltage generated in the current detecting resistor 31. A voltage Vi proportional to the current I flowing through the coil L is supplied to a non-inverting input terminal (+) of a comparator 33, an inverter 34 that inverts the output of the comparator 33 and outputs the inverted signal, SR latch 3 whose output is input to set terminal S
5 and an AND gate 37 for outputting an AND signal of the output of the SR latch 35 and the drive signal SD from the microcomputer 23
And when the output of the AND gate 37 is at a high level,
The MOSFET 21 is turned on by setting the gate of the SFET 21 to the ground level (0 V) as a low level, and conversely, when the output of the AND gate 37 is at the low level, M
The battery voltage (battery 12
And an inverter buffer 39 for supplying the voltage VB to turn off the MOSFET 21.

Further, the electronic control unit 13 has its own input terminal T connected to the output terminal Q of the SR latch 35,
When a high-level signal is output from the SR latch 35, the internal counter starts counting, and when the counting (time counting) of the preset ON time Ton is completed, the output of its own output terminal Q is set to the high level. Invert, and S
When a low level signal is output from the R latch 35, the internal counter is reset, and the output terminal Q of its own is reset.
And an AND signal of an output of an output terminal Q of the timer 41 and an output of an SR latch 61, which will be described later, is connected to a reset terminal R of the SR latch 35.
And an AND gate 43 for outputting to the

When the microcomputer 23 starts outputting the high-level drive signal SD, the electronic control unit 13 changes the reference voltage Vref applied to the inverting input terminal (-) of the comparator 33 to the valve operating current. The voltage Vref (Ipp) is set to a voltage Vref (Ipp) corresponding to the initial control current value Ipp which is larger than the value, and after the microcomputer 23 starts outputting the high-level drive signal SD, the voltage Vi of the current detection resistor 31 is When it is determined that the voltage has increased to the voltage Vref (Ipp) (that is, the conduction current I of the coil L has increased to the initial control current value Ipp), the reference voltage Vref is used as the valve operating current. A voltage Vref (Ip) corresponding to the first control current value Ip,
Further, when a predetermined time Tp has elapsed since the microcomputer 23 started outputting the high-level drive signal SD, the reference voltage Vref was equivalent to a second control current value Ih (<Ip) as the holding current value. A current value setting circuit 29 for setting the voltage to Vref (Ih) is provided.

The current value setting circuit 29 includes four resistors 51 and 52 connected in series between a stable power supply voltage VC generated in the electronic control unit 13 based on the battery voltage VB and the ground. , 53, 54, of which the collector is connected to the connection point of the second and third resistors 52, 53 from the power supply voltage VC side, the NPN transistor 55 whose emitter is connected to ground, and the microcomputer 23 Is input to its own input terminal T, and when the drive signal SD rises from a low level to a high level, the internal counter is reset to output a low level signal from its output terminal Q to the base of the transistor 55. At the same time, the counting operation is started, and the predetermined time Tp
Is completed, a timer 57 for inverting the output of its own output terminal Q to a high level to turn on the transistor 55, and a collector connected to both ends of one of the resistors 51 to 54 on the ground side among the resistors 51 to 54 The output of the comparator 33 is input to a set terminal S, and the output terminal Q is connected to the base of the transistor 59 and one input terminal of the AND gate 43. SR latch 6
1 and an inverter 63 that logically inverts the drive signal SD from the microcomputer 23 and outputs the inverted signal to the reset terminal R of the SR latch 61. Then, of the four resistors 51 to 54, two resistors 5 on the power supply voltage VC side are connected.
The voltage generated at the connection point between the first and second resistors 52
The reference voltage Vref is applied to the inverting input terminal of the comparator 33 as a reference voltage Vref that is compared with the voltage Vi of 1.

In such an electronic control device 13, when both of the two transistors 55 and 59 are off, the reference voltage Vref input to the inverting input terminal of the comparator 33 becomes equal to the initial control current value Ipp (> Ip
> Ih) is set to the voltage Vref (Ipp).

If the resistance values of the four resistors 51 to 54 are R51 to R54, respectively, Vref (Ipp) is represented by the following equation. Vref (Ipp) = VC × (R52 + R53 + R54) /
(R51 + R52 + R53 + R54) Then, the initial control current value Ipp is equal to the voltage Vref (I
pp) is divided by the resistance value of the current detection resistor 31 and a value by which the current I of the coil L can reach that value before the predetermined time Tp has elapsed since the MOSFET 21 was turned on. Is set to

The two transistors 55, 59
Among them, when only the transistor 59 is turned on, one of the four resistors 51 to 54 is in a short-circuit state, and the reference voltage Vref input to the inverting input terminal of the comparator 33 is A voltage Vref (Ip) corresponding to a control current value (valve element operating current value) Ip of 1
Is set to

This Vref (Ip) is represented by the following equation. Vref (Ip) = VC × (R52 + R53) / (R51 +
R52 + R53) Then, the first control current value Ip is equal to the voltage Vref (I
p) is divided by the resistance value of the current detecting resistor 31, and the predetermined time T after the MOSFET 21 is turned on.
If the current I flowing through the coil L of the solenoid valve 6 is controlled to the first control current value Ip until p elapses, the operation when the solenoid valve 6 is energized (the valve closing operation in this example) is ensured. Is set to a value to complete.

On the other hand, when the transistor 55 is turned on, regardless of the on / off state of the transistor 59, two of the four resistors 51 to 54 are short-circuited, and the comparator 33 is inverted. The reference voltage Vref input to the input terminal is set to a voltage Vref (Ih) corresponding to the second control current value (holding current value) Ih.

This Vref (Ih) is represented by the following equation. Vref (Ih) = VC × R52 / (R51 + R52) Then, the second control current value Ih is equal to the voltage Vref (Ih).
h) is divided by the resistance value of the current detection resistor 31, and is set to a current value near the minimum necessary for maintaining the operation of the solenoid valve 6 when current is supplied.

Next, the operation of the electronic control unit 13 will be described with reference to the time chart of FIG. First, when the drive signal SD from the microcomputer 23 is at a low level, the output of the AND gate 37 is forced to a low level, and the MOSFET 21 is continuously turned off. No current flows through the coil L
The voltage Vi of the current detection resistor 31 corresponding to the detected value of the current I is approximately 0V. Therefore, when the drive signal SD is at a low level, the output of the comparator 33 is at a low level, the output of the inverter 34 is at a high level, and the SR latch 35 is set.

For this reason, the drive signal S from the microcomputer 23
When D changes from the low level to the high level, the output of the SR gate 35 is at the high level at that point, and the output of the AND gate 37 is inverted from the low level to the high level, and the MOSFET 21 is immediately turned on. As a result, energization of the coil L of the solenoid valve 6 is started, and an inrush current starts flowing through the coil L.

On the other hand, in the current value setting circuit 29, when the drive signal SD from the microcomputer 23 is at a low level, the SR latch 61 is reset by the inverter 63. When the drive signal SD changes from the low level to the high level, the timer 57 resets the internal counter, outputs a low level signal to the base of the transistor 55, and starts the counting operation.

For this reason, as shown in FIG.
When the drive signal SD from 3 changes from the low level to the high level, both of the two transistors 55 and 59 are turned off, and the reference voltage Vref input to the inverting input terminal of the comparator 33 is changed as described above. ,
The voltage is set to a voltage Vref (Ipp) corresponding to the initial control current value Ipp. That is, the control current value for which the comparator 33 determines the magnitude relationship with the conduction current I is set as the initial control current value Ipp.

Therefore, the drive signal SD from the microcomputer 23
Becomes high level, the comparator 33 compares the voltage Vi of the current detection resistor 31 with the voltage Vref (Ipp) corresponding to the initial control current value Ipp, and the current I of the coil L becomes equal to the initial control current value Ipp. Until it reaches (V
Until i reaches Vref (Ipp)), the comparator 3
The output of No. 3 is maintained at a low level, and the energization of the coil L (the turning on of the MOSFET 21) continues.
Note that this state is shown in FIG. 7 as a period from when the drive signal SD changes to a high level to when the energizing current I of the coil L reaches the initial control current value Ipp.

Thereafter, the current I flowing through the coil L increases to the initial control current value Ipp,
When the output of No. 3 changes from the low level to the high level, the SR latch 61 is set in the current value setting circuit 29, the output of the SR latch 61 changes from the low level to the high level, and the transistor 59 is turned on.

Then, the transistor 59 is turned on and the transistor 55 is turned off, and as described above,
The reference voltage Vref input to the inverting input terminal of the comparator 33 is equal to the voltage Vr corresponding to the first control current value Ip.
ef (Ip). That is, the control current value at which the comparator 33 determines the magnitude relationship with the conduction current I is:
It is set to the first control current value Ip.

Since the output of the timer 41 is at the high level at this point, when the output of the SR latch 61 is at the high level, the SR gate 35 is output from the AND gate 43 to the SR latch 35.
A high-level signal is output to the reset terminal R of
The R latch 35 is reset, and the output of the SR latch 35 is inverted to a low level. When the output of the SR latch 35 goes low, the internal counter of the timer 41 is reset, and the output of the timer 41 returns to low.

Then, the output of the AND gate 37 is inverted to a low level, and the MOSFET 21 is turned off. The off state of the MOSFET 21 depends on the current I flowing through the coil L (in this case, the diode 25 is turned off). The arc extinguishing current flowing through the coil L through the first control current value I
p, the voltage Vi of the current detection resistor 31 decreases to the voltage Vref (Ip) corresponding to the first control current value Ip, and the output of the comparator 33 changes from the high level to the low level. continue. That is, when the energizing current I of the coil L decreases to the first control current value Ip and the output of the comparator 33 is inverted to a low level, the SR latch 35 is set again to set the SR latch 3
5 becomes high level, and the MOSFET 21 is turned on again.

At this time, the high-level signal output from the SR latch 35 is also input to the input terminal T of the timer 41. Therefore, the timer 41 determines when the output of the SR latch 35 becomes high (MOSFET 21). When the counting of the internal counter is completed for a predetermined time period, the AND gate 4 is activated.
3, a high-level signal is output to one input terminal.

At this point, the SR latch 61 is in the set state, and the output of the SR latch 61 is at a high level.
When the high level signal is output, the SR latch 35 is reset by the AND gate 43, the output of the SR latch 35 is inverted to low level, and the MOSFET 21 is turned off again.

Thereafter, from the time when the microcomputer 23 sets the drive signal SD to the high level to the time when the predetermined time Tp counted by the timer 57 elapses, the current I of the coil L is controlled by the comparator 33 to the first control current value. Each time it is determined that the output has decreased to Ip (Vi has decreased to Vref (Ip)) and the output of the comparator 33 goes low,
The operation that the MOSFET 21 is turned on for a fixed time Ton as the on-time measured by the timer 41 is repeated, and by such an operation, the conduction current I of the coil L is controlled near the first control current value Ip. Is done.

When a predetermined time Tp elapses from the time when the microcomputer 23 sets the drive signal SD to the high level, the output of the timer 57 is inverted to the high level. Then, the transistor 55 is turned on, and as described above, the reference voltage Vref input to the inverting input terminal of the comparator 33 is output.
Is set from the voltage Vref (Ip) to a voltage Vref (Ih) corresponding to the second control current value Ih. That is, the control current value at which the comparator 33 determines the magnitude relationship with the conduction current I is set to the second control current value Ih.

Therefore, from the time when the predetermined time Tp has elapsed until the drive signal SD from the microcomputer 23 becomes low level, the above-described current detecting resistor 31, comparator 33, inverter 34, SR latch 35, AND Due to the operation of the circuit including the gate 37, the inverter buffer 39, the timer 41, and the AND gate 43, the conduction current I of the coil L is reduced by the comparator 33 to the second control current value Ih (Vi becomes Vref (Ih)). Every time the output of the comparator 33 becomes low level, the operation of turning on the MOSFET 21 for a certain time Ton measured by the timer 41 is repeated. The current I flowing through the coil L is controlled near the second control current value Ih.

The drive signal SD from the microcomputer 23
Becomes low level, the output of the AND gate 37 is forced to be low level, so that the MOSFET 21 is turned off regardless of the current I flowing through the coil L. That is, in the electronic control unit 13 of FIG. 6, when the microcomputer 23 starts outputting the high-level drive signal SD, the MOSF
ET21 is turned on, and when the current I flowing through the coil L reaches the initial control current value Ipp, the MOSFET 21 is turned off. Then, when a predetermined time Tp elapses from the time when the microcomputer 23 sets the drive signal SD to the high level. First up to
Until the end of the period (the period indicated by K1 in FIG. 7), each time it is determined that the conduction current I of the coil L has decreased to the first control current value Ip, the MOSFET 21 is set to the predetermined time To.
By turning on only n, the current I flowing through the coil L is controlled near the first control current value Ip, and the predetermined time Tp
In the second period (period indicated by K2 in FIG. 7) from when the drive signal SD goes to the low level after elapse, it is determined that the conduction current I of the coil L has decreased to the second control current value Ih. Each time the current is turned on, the MOSFET 21 is turned on for the above-mentioned fixed time Ton, so that the current flowing through the coil L is controlled to be close to the second control current value Ih.

The solenoid valve 6 quickly changes from the open state to the closed state by supplying a current near the first control current value Ip to the coil L during the first period K1. In the second period K2, the second control current value Ih smaller than the first control current value Ip is applied to the coil L.
By supplying the current in the vicinity, the valve-closed state is maintained, and the drive control of the solenoid valve 6 and the reduction of the power supply current I to achieve low power consumption are achieved by such power supply control. .

[0036]

By the way, in the above-mentioned conventional electronic control unit 13, the current flowing through the coil L when the MOSFET 21 is turned on is represented by Irh and Ir in FIG.
As can be seen from the comparison with rp, if the on-time Ton of the MOSFET 21 is the same, the on-time Ton increases greatly in the lower current range.

For this reason, as shown in FIG. 7, the second period K for holding the valve body 6a of the solenoid valve 6 at the energizing operation position is set.
The fluctuation range of the current I flowing through the coil L during
a for the first period K for moving a to the energizing operation position
1 is larger than the fluctuation range of the conduction current I during the period of time 1.

Therefore, in the above-mentioned conventional electronic control device 13, the average value of the energizing current in the second period K2 in which the energizing current is originally desired to be suppressed as much as possible becomes large.
There is a problem in that lower power consumption and a reduction in the size of the switching element are limited. Therefore, it is conceivable to set the ON time Ton measured by the timer 41 to be short. However, if the ON time Ton is simply shortened, the time required for the switching element to operate in a linear area (an area where the switching element is not sufficiently turned on) is reduced. The ratio increases, and in particular, the power loss (switching loss) in the first period K1 where the conduction current is large increases.
This causes an increase in the size of the switching element. Also, in particular,
When driving an electromagnetic valve used to supply fuel to the engine, such as the electromagnetic valve 6, as the engine speed increases, the interval between the set energization periods (ie,
The non-energizing period is shortened, and the time ratio of the first period K1 is increased, so that the heat generated by the switching element is increased. In order to exhibit stable performance up to a higher rotation range, a large switching element is required. Is required. Note that if a switching element having a high switching speed is used, switching loss can be reduced, but such a switching element is generally expensive.

The present invention has been made in view of the above-described problems, and an electromagnetic valve driving device capable of realizing a high level of driving response, low power consumption, and downsizing of a switching element of an electromagnetic valve. It is intended to provide.

[0040]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, the solenoid valve driving device of the present invention according to the first aspect of the present invention provides a solenoid valve driving device which has a current path for flowing a current to a coil of the solenoid valve. A switching element for supplying a current to the coil to drive the solenoid valve when turned on, a power supply period setting unit for setting a power supply period to the coil, and a power supply period setting unit. And an energization control unit for turning on the switching element so that an energization current flowing through the coil has a predetermined control current value during the energization period.

The energization control means turns on the switching element at the start timing of the energization period set by the energization period setting means, and sets the switching element after the energization current flowing through the coil exceeds the first control current value Ip. Is turned off, and then a predetermined time T from the start of the energization period.
Until the time when p elapses, the switching element is turned on only for the first ON time T1 every time it is determined that the current flowing through the coil has decreased to the first control current value Ip. Control is performed near the first control current value Ip. Further, the energization control means further includes the predetermined time T
After the elapse of p, the current supplied to the coil is smaller than the first control current value Ip until the current period ends.
Every time it is determined that the control current value has decreased to the control current value Ih,
By turning on only for the ON time T2, the current supplied to the coil is controlled to the vicinity of the second control current value Ih.

That is, in the solenoid valve driving device of the present invention, the same energization control as in the above-described conventional device 13 is performed.
A first period in which the ON time for temporarily turning on the switching element each time it is determined that the energizing current of the coil has decreased to the control current value, the energizing current of the coil is controlled near the first control current value Ip; The energizing current of the coil is changed in the second period in which the current is controlled near the second control current value Ih (<Ip), and the on-time (second on-time) T2 in the second period is changed in the first period. The ON time (first ON time) is shorter than T1.

Therefore, according to the solenoid valve driving device of the present invention, the energizing operation of the valve body of the solenoid valve is performed without increasing the power loss (switching loss) in the switching element in the first period in which the current is large. The fluctuation range of the energizing current in the second period for holding the current in the position can be suppressed small, and the average value of the energizing current in the second period can be suppressed. Therefore, the problem of the conventional device 13 is solved,
The drive response of the solenoid valve, low power consumption, and downsizing of the switching element can be realized at a high level.

In particular, the electromagnetic valve to be driven is an electromagnetic valve used to supply fuel to the vehicle engine, and the energization period setting means is synchronized with the rotation of the engine. In the case of a configuration in which the energization period to the coil of the solenoid valve is set, as described above, as the engine speed increases, the interval between the energization periods to be set decreases, and the first Since the time ratio of the period increases, the heat generation of the switching element tends to increase. However, according to the solenoid valve driving device of the present invention, the temporary ON time T1 during the first period in which the current is large is not shortened. Since the switching loss during the first period is not increased, a small switching element can exhibit stable performance up to a higher rotation range, which is very advantageous. That.

In this case, the electromagnetic valve to be driven may be an electromagnetic valve used for a high-pressure fuel pump for adjusting the pressure of fuel supplied to the engine, as described in claim 6. Further, a fuel injection valve for injecting fuel into the engine may be used.

By the way, the solenoid valve driving device of claim 1 is
It can be configured as described in claim 2. That is, in the solenoid valve driving device according to claim 2, first, the energization period setting unit sets the energization period to the coil,
During the set energization period, a drive signal for turning on the switching element is output.

The energization control means detects an energizing current flowing through the coil and determines a magnitude relationship between the energizing current and a predetermined control current value. It comprises control current value setting means for setting a value, driving means for turning on / off the switching element, and on-time changing means.

Here, the control current value setting means determines when the energization period setting means starts to output the drive signal (ie,
The control current value to be determined by the determination means is set to an initial control current value Ipp larger than the first control current value Ip from the start timing of the power supply period), and the power supply period setting means outputs the drive signal. After the start, the current supplied to the coil by the determination means is reduced to the initial control current value Ip.
When it is determined that the current has increased to p, the determining means resets the control current value to be determined to the first control current value Ip, and further, the energization period setting means starts outputting the drive signal. When the predetermined time Tp elapses, the control current value to be determined by the determination means is set to the second control current value Ih at least until the output of the drive signal is stopped.

When the energizing period setting means starts outputting the driving signal, the driving means turns on the switching element, and the judging means controls the energizing current of the coil by the control current value set by the controlling current value setting means. When it is determined that the current has increased to the value (at this time, the initial control current value Ipp), the switching element is turned off. Each time it is determined that the energizing current has decreased to the control current value set by the control current value setting means, the switching element is turned on for a predetermined ON time, and the output of the drive signal is stopped. The switching element is turned off irrespective of the judgment result of the judging means.

Further, the on-time changing means is configured to control the on-time (driving) of the driving means during the first period from the time when the energization period setting means starts outputting the driving signal until the predetermined time Tp elapses. Means for temporarily turning on the switching element) is set to the first on-time T1;
During a second period from the elapse of the predetermined time Tp to the stop of the output of the drive signal, the on-time of the drive unit is set to the second on-time T2 (<T1).

That is, in this solenoid valve driving device, at the start timing of the energizing period during which the driving signal is output from the energizing period setting unit, the switching element is turned on by the driving unit, and the energizing current of the coil is set to the first control current value. When the switching element increases to the initial control current value Ipp larger than Ip, the switching element is once turned off by the driving unit.

Thereafter, until the first period from when the energization period setting unit starts outputting the drive signal to when the predetermined time Tp elapses, the energization current of the coil is reduced by the determination unit until the first period elapses. Each time it is determined that the control current value has decreased to the control current value Ip, the driving means turns on the switching element for the first ON time T1.

During the second period from when the predetermined time Tp elapses to when the energizing period setting means stops outputting the drive signal, the judging means makes the energizing current of the coil reach the second control current value Ih. Each time it is determined that the voltage has decreased, the driving means turns on the switching element for the second ON time T2.

When the energization period setting means stops outputting the drive signal, the switching element is not turned on by the drive means. For this reason, the above-mentioned operation by the power supply control means of claim 1 is realized. According to the solenoid valve driving device of the second aspect, when a microcomputer is used as the energization period setting means, the energization control means can be constituted by a hardware circuit independent of the microcomputer, and the energization control means can be constituted. The above-described effects can be obtained without increasing the processing load on the microcomputer as the period setting means at all.

On the other hand, in the electromagnetic valve driving device according to the second aspect, the driving means and the on-time changing means can be configured as described in the third aspect. That is, in the solenoid valve driving device according to the third aspect, first, the driving means switches each time the determining means determines that the current supplied to the coil has decreased to the control current value set by the control current value setting means. As means for turning on the element for a predetermined ON time, a first timer, a second timer, and ON permission means are provided.

When the determining means determines that the current supplied to the coil has decreased to the control current value set by the control current value setting means, the first timer determines whether the first on-time T1 has elapsed. When the time measurement is started and the measurement of the first ON time T1 is completed, a signal indicating that the first ON time T1 has elapsed is output from the output terminal. Also,
When the determination means determines that the current supplied to the coil has decreased to the control current value set by the control current value setting means, the second on-time T2
When the timing of the second ON time T2 is completed, a signal indicating that the second ON time T2 has elapsed is output from the output terminal. When the determination unit determines that the current supplied to the coil has decreased to the control current value set by the control current value setting unit, the ON permission unit determines which of the first and second timers. The switching element is turned on until the signal from either one is input to a specific input terminal.

Further, in the electromagnetic valve driving device according to the third aspect, the on-time changing means is configured to switch the on-time changing means during the first period from when the energizing period setting means starts outputting the driving signal to when the predetermined time Tp elapses. Connecting the output terminal of the first timer and the input terminal of the on-permission means, and during the second period from the lapse of the predetermined time Tp until the output of the drive signal is stopped, Is connected to the input terminal of the ON permission means.

According to the electromagnetic valve driving device of the third aspect, the structures of the driving means and the on-time changing means can be simplified. On the other hand, in the solenoid valve driving device according to the second aspect, the driving unit and the on-time changing unit may be configured as described in the fourth aspect.

That is, in the solenoid valve driving device according to the fourth aspect, first, the driving means determines that the energizing current of the coil has decreased to the control current value set by the control current value setting means by the judging means. Further, a timer and an ON permission means are provided as means for turning on the switching element for a predetermined ON time.

When the judging means judges that the current supplied to the coil has decreased to the control current value set by the control current value setting means, the timer starts the time counting operation, and When the ON time T2 elapses, the second
A signal indicating that the second on-time T2 has elapsed is output from an output terminal of the first output terminal, and when the first on-time T1 has elapsed, it is determined that the first on-time T1 has elapsed from the first output terminal. Output the signal shown. On-permission means, when the determination means determines that the current supplied to the coil has decreased to the control current value set by the control current value setting means, turns on the first and second output terminals of the timer. The switching element is turned on until the signal from any one of them is input to a specific input terminal.

Further, in the electromagnetic valve driving device according to the third aspect, the on-time changing means is provided during the first period from the time when the energization period setting means starts outputting the drive signal to the time when the predetermined time Tp elapses. Connecting a first output terminal of the timer and an input terminal of the ON permission means, and during the second period from the lapse of the predetermined time Tp until the output of the drive signal is stopped, A second output terminal is connected to an input terminal of the ON permission means.

That is, in the solenoid valve driving device of the third aspect,
A timer for measuring the first ON time T1 and a timer for measuring the second ON time T2 are separately provided. The ON time T1 and the second ON time T2 are measured by one timer. Therefore, according to the electromagnetic valve driving device of the fourth aspect, the configuration of the driving means can be further simplified.

[0063]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic control device as a solenoid valve driving device according to an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 is a circuit diagram illustrating a configuration of an electronic control unit 65 according to the first embodiment.

The electronic control unit according to the present embodiment is similar to that shown in FIGS.
5 is used in place of the conventional electronic control unit 13 in the control system for a direct injection engine shown in FIG.
In FIG. 1, the same components as those of the electronic control device 13 in FIG. 6 are denoted by the same reference numerals, and thus detailed description is omitted.

As shown in FIG. 1, the electronic control unit 65 of the first embodiment is different from the device 13 of FIG.
-1) and (1-2) are different. (1-
1): First, instead of the timer 41 in FIG. 6, a first timer 41a and a second timer 41b having the same functions as the timer 41 are provided.

When the high level signal is output from the SR latch 35, the first timer 41a starts the counting operation of the internal counter, and counts the first ON time T1 set in advance (time measurement). Is completed, the output of its own output terminal Q is inverted to a high level. When the low level signal is output from the SR latch 35, the internal counter is reset and the output of its own output terminal Q is set to a low level. To level. On the other hand, the second timer 41b
When a high-level signal is output from the SR latch 35, the internal counter starts counting, and when the counting (time counting) of the second ON time T2 set in advance is completed,
When the output of its own output terminal Q is inverted to a high level and a low level signal is output from the SR latch 35, the internal counter is reset and the output of its own output terminal Q is set to a low level.

Further, in the present embodiment, the first ON time T1 measured by the first timer 41a is the same as the ON time Ton measured by the timer 41 of the conventional device 13 shown in FIGS. However, the second ON time T2 measured by the second timer 41b is set to a time shorter than the first ON time T1.

(1-2): Next, when the electronic control unit 65 of the present embodiment outputs a low-level signal from the output terminal Q of the timer 57, one of the input terminals of the AND gate 43 (SR latch) The input terminal of the first timer 41a is connected to the input terminal on the opposite side to the one to which the output of the output terminal 61 is input, and the output terminal Q of the first timer 41a. And a signal switching circuit 69 for connecting the one input terminal of the AND gate 43 and the output terminal Q of the second timer 41b when a high-level signal is output from the output terminal Q of the second timer 41b.

In the electronic control device 65 of the first embodiment as described above, as shown in FIG. 2, the predetermined time Tp measured by the timer 57 from the time when the microcomputer 23 outputs the high-level drive signal SD is set. During the first period K1 until the elapse, the output terminal Q of the first timer 41a and one input terminal of the AND gate 43 are connected by the signal switching circuit 69. MOSFET as switching element after reaching control current value Ipp
When the power supply 21 is turned off, the MOSFET 21 is turned off every time the comparator 33 determines that the current I flowing through the coil L has decreased to the first control current value Ip until the first period K1 ends. It is temporarily turned on for the first ON time T1 measured by the first timer 41a, and by repeating such an operation, the conduction current I is controlled near the first control current value Ip.

During the second period K2 from the elapse of the predetermined time Tp until the drive signal SD goes low, the signal switching circuit 69 causes the output terminal Q of the second timer 41b and the AND gate 43 Since one input terminal is connected, the current I flowing through the coil L becomes the second control current I
h, the MOSFET 21 is temporarily turned on for the second on-time T2 measured by the second timer 41b every time the comparator 33 determines that the current has decreased to h. The control current value is controlled to around the control current value Ih.

Here, in particular, in the electronic control unit 65 of the first embodiment, each time it is determined that the current I flowing through the coil L has decreased to the control current value, the ON time for temporarily turning on the MOSFET 21 is determined by the coil time. A first period K1 for controlling the energizing current I of the L to a vicinity of the first control current value Ip;
In the second period K2 in which the current I is controlled to be close to the second control current value Ih (<Ip), and the ON time (second ON time) T2 in the second period K2 is changed to the first period. It is shorter than the on-time (first on-time) T1 during K1.

For this reason, according to the electronic control unit 65 of the first embodiment, as can be seen from a comparison between FIG. 2 and FIG. 7, the valve body 6a of the solenoid valve 6 is held at the energizing operation position. The fluctuation range of the conduction current I in the second period K2 can be suppressed small, and the average value of the conduction current I in the second period K2 can be suppressed. In addition, the ON time T1 in the first period K1 in which the conduction current I itself is large is the same as that of the conventional device 13 and is not short, so that the power loss (switching loss) in the MOSFET 21 in the first period K1 is increased. Nothing.

Therefore, according to the electronic control unit 65,
Not only can the total current flowing through the coil L be reduced,
P-channel MOSFET 21 as switching element
Can be reduced, and the drive response and low power consumption of the solenoid valve 6 and the switching element (here, P
The size of the channel MOSFET 21) can be reduced to a higher level. In particular, in the electronic control device 65, the higher the engine speed, the shorter the interval between the energization periods set by the microcomputer 23 as the energization period setting means, and the greater the time ratio of the first period K1. In the first period K1, the heat generated by the MOSFET 21 is likely to increase. However, the temporary ON time T1 is not shortened, and the switching loss of the MOSFET 21 is not increased. Can be demonstrated.

In the electronic control unit 65 of the first embodiment, the current detecting resistor 31, the comparator 33, the inverter 34, the SR latch 35, the AND gate 37,
A circuit portion including the inverter 43, the inverter buffer 39, the first and second timers 41a and 41b, the signal switching circuit 69, and the current value setting circuit 29 corresponds to an energization control unit.

Among them, the current detecting resistor 31 and the comparator 33 correspond to the judgment means, the current value setting circuit 29 corresponds to the control current value setting means, and the inverter 34
, SR latch 35, AND gates 37 and 43, inverter buffer 39, first and second timers 41
a and 41b correspond to the driving means,
The signal switching circuit 69 corresponds to on-time changing means.
Further, a circuit portion including the inverter 34, the SR latch 35, and the AND gate 43 corresponds to the ON permission means.

Next, a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, the electronic control unit 71 of the second embodiment is different from the electronic control unit 65 of the first embodiment in the following (2-1) and (2-2).
Is different.

(2-1) First, instead of the first and second timers 41a and 41b, one timer 73 capable of measuring the first ON time T1 is provided. When a high-level signal is output from the SR latch 35, the timer 73 starts counting by an internal counter.
When the count (time measurement) of the second ON time T2 (<T1) is completed, the output of the second output terminal QB is inverted to a high level, and when the count of the first ON time T1 is completed, the first output terminal is output. The output of QA is inverted to high level.
When a low level signal is output from the SR latch 35, the internal counter is reset and the first counter is reset.
And the outputs of the second output terminals QA and QB are set to low level.

(2-2): When the low level signal is output from the output terminal Q of the timer 57, the signal switching circuit 69 receives one input terminal of the AND gate 43 (the output of the SR latch 61). And a terminal corresponding to the specific input terminal according to claim 4).
And the first output terminal QA of the timer 73, and when the high level signal is output from the output terminal Q of the timer 57, the one input terminal of the AND gate 43 and the second output terminal of the timer 73 Connect to QB.

That is, in the electronic control unit 65 of the first embodiment described above, the timer 41a for measuring the first ON time T1 and the timer 41b for measuring the second ON time T2 are separately provided. However, in the electronic control device 71 of the second embodiment, the second on-time T2 and the first on-time T1 are set to one having one continuous internal counter.
The time is measured by two timers 73.

According to the electronic control unit 71 of the second embodiment, the same effects as those of the electronic control unit 65 of the first embodiment can be obtained with fewer circuit elements. As mentioned above, although one Embodiment of this invention was described, it cannot be overemphasized that this invention can take various forms.

For example, the electronic control unit 6 of each of the above embodiments
5 and 71 (FIGS. 1 and 3), a microcomputer having a built-in A / D converter is used as the microcomputer 23, and the voltage Vi generated in the current detecting resistor 31 is input to the A / D conversion input of the microcomputer 23. The operation of the circuit portion other than the current detecting resistor 31 and the inverter buffer 39 in the circuit portion corresponding to the energization control means may be realized by the arithmetic processing of the microcomputer 23. However, the configuration as in each of the above-described embodiments is advantageous in that the processing load on the microcomputer 23 is not increased at all.

On the other hand, the electronic control unit 6 of each of the above embodiments
5, 71 drive the electromagnetic valve 6 used in the high-pressure fuel pump 3 for adjusting the pressure of the fuel supplied to the direct injection type engine. The present invention is not limited to the electromagnetic valve 6, and may be, for example, an electromagnetic fuel injection valve (injector) for injecting fuel into the engine or an electromagnetic spill valve used for a fuel injection pump of a diesel engine.

The present invention can be similarly applied to a device for driving an electromagnetic valve other than the electromagnetic valve used for supplying fuel to the vehicle engine.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a configuration of an electronic control device (an electromagnetic valve driving device) according to a first embodiment.

FIG. 2 is a time chart illustrating an operation of the electronic control device of the first embodiment.

FIG. 3 is a circuit diagram illustrating a configuration of an electronic control device (an electromagnetic valve driving device) according to a second embodiment.

FIG. 4 is a configuration diagram illustrating a control system of a direct injection engine.

FIG. 5 is a configuration diagram illustrating a high-pressure fuel pump.

FIG. 6 is a circuit diagram illustrating a configuration of a conventional solenoid valve driving device.

FIG. 7 is a time chart showing the operation and problems of a conventional solenoid valve driving device.

FIG. 8 is a graph showing a current change characteristic of a coil with respect to an ON time of a switching element.

[Explanation of symbols]

3: High pressure fuel pump 6: Solenoid valve L: Coil
6a ... valve element 6b ... return spring 12 ... battery 6
5, 71: electronic control unit 21: P-channel MOSFET 23: microcomputer
29: current value setting circuit 31: current detection resistor 33: comparator 3
4, 63 inverter 35, 61 SR latch 37, 43 AND gate 39 inverter buffer 41a, 41b, 57,
73: timer 51, 52, 53, 54: resistor 55, 59: NPN
Transistor 61: Signal switching circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // F02M 51/06 F02M 51/06 M

Claims (7)

[Claims] A switching element that is provided in a current path for flowing a current to a coil of the solenoid valve and that is turned on to flow a current to the coil to drive the solenoid valve; Energization period setting means for setting, and energization control means for turning on the switching element such that an energization current flowing through the coil has a predetermined control current value during the energization period set by the energization period setting means. The energization control unit turns on the switching element at a start timing of the energization period set by the energization period setting unit, and sets the switching element after an energization current flowing through the coil exceeds a first control current value. Is turned off, and thereafter, until a predetermined time elapses from the start of the energization period, the energization current flowing through the coil is equal to the first current. Each time it is determined that the current has decreased to the control current value, the switching element is turned on for a first ON time to control the conduction current to be close to the first control current value, and the predetermined time has elapsed. After that, until the current supply period ends, every time it is determined that the current supply has decreased to a second control current value smaller than the first control current value, the switching element is turned on by the first ON. An electromagnetic valve driving device, wherein the energizing current is controlled to be close to the second control current value by being turned on for a second ON time shorter than the time. 2. The solenoid valve driving device according to claim 1, wherein the energization period setting means is configured to perform the operation during the set energization period.
A drive signal for turning on the switching element, the energization control unit detects an energization current flowing through the coil, and determines a magnitude relationship between the energization current and a predetermined control current value. A control current value to be determined by the determination unit from the time when the energization period setting unit starts outputting the drive signal,
An initial control current value larger than the first control current value is set, and the energizing current is set to the initial control current value by the determination unit after the energization period setting unit starts outputting the drive signal. When it is determined that the current value has increased, the control current value to be determined by the determination means is set to the first control current value, and further, after the energization period setting means starts outputting the drive signal, When a predetermined time has elapsed, at least until the output of the drive signal is stopped,
Control current value setting means for setting the control current value to be determined by the determination means to the second control current value; and when the energization period setting means starts outputting the drive signal, the switching element is turned on. When the determining unit determines that the energizing current has increased to the control current value set by the control current value setting unit, the control unit turns off the switching element, and then stops the output of the drive signal. In the meantime, the switching element is turned on for a predetermined on-time every time the determining means determines that the supplied current has decreased to the control current value set by the control current value setting means. Driving means for turning off the switching element irrespective of the judgment result of the judging means when the output of the driving signal is stopped; During the first period from the time between setting means starts the output of the drive signal until the predetermined time elapses,
The on-time of the driving means is set to the first on-time, and the on-time of the driving means is set during a second period from the elapse of the predetermined time until the output of the driving signal is stopped. And an on-time changing means for setting the second on-time to the second on-time. 3. The solenoid valve driving device according to claim 2, wherein the drive unit determines that the energizing current has decreased to the control current value set by the control current value setting unit by the determination unit. Each time the switching element is turned on for a predetermined on-time, the determining means determines that the conduction current has decreased to the control current value set by the control current value setting means. Starting the timing of the first on-time, and completing the timing of the first on-time; outputting a signal indicating that the first on-time has elapsed from an output terminal; When the determining means determines that the energizing current has decreased to the control current value set by the control current value setting means, the second on-time starts counting. A second timer for outputting a signal indicating that the second on-time has elapsed from an output terminal when the timing of the second on-time has been completed; When it is determined that the control current value has decreased to the control current value set by the setting means, the time until the signal from one of the first and second timers is input to a specific input terminal And an on-permission means for turning on the switching element, wherein the on-time changing means connects an output terminal of the first timer and an input terminal of the on-permission means during the first period, and Connecting the output terminal of the second timer and the input terminal of the ON permission means during two periods. 4. The electromagnetic valve driving device according to claim 2, wherein the drive unit determines that the energizing current has decreased to the control current value set by the control current value setting unit by the determination unit. Each time the switching element is turned on for a predetermined on-time, the determining means determines that the conduction current has decreased to the control current value set by the control current value setting means. Starting a timing operation, outputting a signal indicating that the second on-time has elapsed from the second output terminal when the second on-time has elapsed, and outputting a signal indicating that the first on-time has elapsed. A timer for outputting a signal indicating that the first on-time has elapsed from an output terminal of the first output terminal; and a control current value setting means for setting the energizing current by the determination means. When it is determined that the control current value has decreased to a certain control current value, the switching is performed until the signal from one of the first and second output terminals of the timer is input to a specific input terminal. On-permission means for turning on an element, wherein the on-time changing means connects a first output terminal of the timer to an input terminal of the on-permission means during the first period; And a second output terminal of the timer and an input terminal of the ON permission means are connected. 5. The electromagnetic valve driving device according to claim 1, wherein the electromagnetic valve is an electromagnetic valve used to supply fuel to a vehicle engine, and the energization period setting is performed. Means for setting the energization period in synchronization with the rotation of the engine; 6. The electromagnetic valve driving device according to claim 5, wherein the electromagnetic valve is an electromagnetic valve used for a high-pressure fuel pump for adjusting a pressure of a fuel supplied to the engine. Valve drive to be used. 7. The electromagnetic valve driving device according to claim 5, wherein the electromagnetic valve is a fuel injection valve that injects and supplies fuel to the engine.