JP3222012B2 - Solenoid valve drive circuit - Google Patents

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 circuit, and more particularly, to a solenoid valve driving circuit used for a fuel injection device of an engine.

[0002]

2. Description of the Related Art In a fuel injection device for an engine, there is known an electromagnetic valve which overflows high-pressure fuel based on a drive signal at a predetermined timing from a control computer. Such an electromagnetic valve operates by being driven by an electrically operated solenoid coil. In order to operate such an electromagnetic valve in accordance with the drive signal, when performing fuel injection in response to the drive signal, for example, when supplying current to the solenoid coil, the current flowing through the solenoid coil is quickly started to increase the solenoid. When the fuel injection is stopped in response to the drive signal, for example, when the current to be supplied to the solenoid coil is cut off, the current flowing through the solenoid coil is quickly lowered to set the solenoid coil to the non-operation region. It is necessary that

[0003] If the above requirements are not satisfied, for example, when the engine rotates at high speed, the fuel injection amount cannot be appropriately provided in each fuel injection cycle, and when the above requirements are not satisfied. As described above, as described above, it becomes impossible to provide an appropriate fuel injection amount in the fuel injection cycle, and at the same time, the injection stop timing is delayed, so that harmful components in the exhaust gas are increased.

FIGS. 5 and 6 show an example of a conventional solenoid valve driving circuit. FIG. 5 is a circuit diagram thereof, and FIG. 6 schematically shows a voltage or current waveform of each circuit in FIG. It is a time chart shown. In this solenoid valve driving circuit, a resistor 52 is provided between an emitter of a transistor 51 and a ground potential terminal.
The reference voltage _VSA is compared with the reference voltage _VSA, and the transistor 51 is controlled in accordance with the comparison result, so that a constant current is supplied to the solenoid coil 42.
Further, the inverter 54, the transistor 55, and the resistor 5
Reference numeral 6 is provided to supply the output of the voltage comparison circuit 53 to the ground potential terminal to turn off the transistor 51 when the drive signal from the electronic control device is at a low level. The electromagnetic valve driving circuit, when operating the solenoid coil 42, but allows supply a constant current to the solenoid coil 42, the voltage V _B solenoid of the battery coil 42
Therefore, as shown in FIG. 6, there is a disadvantage that the rise of the current flowing through the solenoid coil 42 is slow.
In addition, the solenoid valve drive circuit is provided with a solenoid coil 42
When the power supply is inactivated, the energy in the solenoid coil 42 is consumed through the Zener diode 57, so that there is a disadvantage that the energy of the battery is consumed excessively.

[0005] In order to solve the drawbacks of the conventional, leave stored in the capacitor to boost the voltage V _B of the battery by using a transformer, when operating the solenoid coil, a high voltage which has been stored in the capacitor A method of quickly operating a solenoid coil by discharging electric charge is known. However, such a method has a problem that it is costly to construct a booster circuit including a transformer.

As another example of a conventional solenoid valve driving circuit, Japanese Patent Laid-Open Publication No. 57-49059 discloses a low-cost circuit configuration as shown in FIG. It is proposed to start up. The solenoid valve drive circuit includes a solenoid coil 42
When the solenoid becomes inoperative, the energy in the solenoid coil 42 is recovered and stored in the capacitor 75, and when the solenoid coil 42 is operated, the high voltage stored in the capacitor 75 is applied to the solenoid coil 42. By doing so, the current rises rapidly in the solenoid coil.

[0007] The electromagnetic valve driving circuit of FIG. 7, one end of the solenoid coil 42 is connected through a diode 71 to a high potential terminal V _B of the battery, also the other end of the solenoid coil 42, transistor 72, resistor 73 Is connected to the ground potential terminal through
4 through a capacitor 75 and a Zener diode 76
And a transistor 77 that enables the voltage of the capacitor 75 to be applied to the solenoid coil 42. When a drive signal to the electromagnetic valve driving circuit is provided, on the one hand also supplied to the battery voltage V is _B will be given, the drive signal is flip-flop 78 on the other hand to the solenoid coil 42 the transistor 72 is turned on, is, since thereby the output of the flip-flop 78 turns on transistor 79, in the initial stage of the drive signal is given, that the high voltage of the capacitor 75 than the battery voltage V _B is applied to the solenoid coil 42 Become. The solenoid valve driving circuit compares the potential of the connection point c between the transistor 72 and the resistor 73 with the reference voltage V _SB using the comparison circuit 80, and compares the potential of the connection point c with the reference voltage V _SB. Higher than flip-flop 7
8 to turn off the transistor 79, the capacitor 75 causes the solenoid coil 4
2 is shut off.

Although the solenoid valve drive circuit can improve the speed of rise of the current when the solenoid coil 42 operates, the potential of the connection point c is compared based on the current flowing through the solenoid coil 42. for you are, the voltage of the capacitor 75 after operating the solenoid coil is effectively becomes the battery voltage V _B. Therefore, if the recovery of energy in the solenoid coil when the solenoid coil is deactivated to the capacitor 75, will be so charged from the battery voltage V _B is started at the capacitor 75 diode 74 current continues to flow through the solenoid coil There is a problem that the fall of the current in the transistor does not become steep. In other words, the capacitor 75 the energy in the solenoid coil in recovering the capacitor 75, the voltage of the capacitor 75 corresponds to approximately the battery voltage V _B, when the recovery of energy according
Slope of the current flowing through the circuit, “d _i / d _t = −V _B / L
(Where L is the inductance of the solenoid coil) "is small. Further, even if the capacitor 75 is charged in the recovery of the energy, the charging speed is very slow, and there is a problem that it takes a considerable period to reach a voltage sufficient to improve the rise of the solenoid coil. .

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to an electromagnetic valve driving circuit according to the present invention, in which the rise of the current when the solenoid coil is activated is rapidly and rapidly increased, and the current when the solenoid coil is deactivated is increased. It is an object of the present invention to provide an inexpensive solenoid valve driving circuit that can quickly make the falling of the solenoid valve sharp.

[0010]

Means for Solving the Problems In order to solve the above problems, the present invention uses the following embodiments. According to the first aspect of the present invention, a first voltage application circuit that applies a DC power supply voltage to a solenoid coil in response to a drive signal for driving an electromagnetic valve, and the solenoid is connected to the solenoid coil, A power storage circuit that stores energy in the solenoid coil at a voltage higher than the DC power supply voltage when the coil is in a non-operating state; and stores the stored voltage stored in the power storage circuit in the solenoid coil in response to the drive signal. An electromagnetic valve driving circuit having a second voltage application circuit for applying the voltage, wherein the second voltage application circuit compares a voltage of the power storage circuit with a predetermined voltage lower than the storage voltage and higher than a DC power supply voltage. A comparison circuit that performs the operation and applies the voltage of the power storage circuit to the solenoid coil in response to the drive signal only when the voltage of the power storage circuit is higher than the predetermined voltage. Electromagnetic valve driving circuit characterized by comprising a circuit for is provided.

According to a second aspect of the present invention, there is provided a first voltage application circuit for applying a DC power supply voltage to a solenoid coil in response to a drive signal for driving an electromagnetic valve; A power storage circuit that is connected to store energy in the solenoid coil at a voltage higher than the DC power supply voltage when the solenoid coil is in a non-operating state; and that the storage voltage stored in the power storage circuit is responsive to the drive signal. And a second voltage application circuit for applying a voltage to the solenoid coil from the time of application when the voltage of the power storage circuit is applied to the solenoid coil. A circuit for setting a time until the voltage decreases to a predetermined voltage or less higher than the DC power supply voltage; and a circuit for setting the power storage circuit in response to the drive signal. Electromagnetic valve driving circuit being characterized in that a pressure and a circuit for applying only the set time is provided.

In a preferred embodiment of the present invention,
Preferably, a diode is connected to one end of the solenoid coil, and an anode of the diode is connected to a ground potential terminal or a high potential terminal of a DC power supply.

[0013]

According to the first and second embodiments, in any of the embodiments, when operating the solenoid coil,
A high storage voltage of the storage circuit is applied to the solenoid coil. The stored voltage is obtained by rapidly storing energy in the solenoid coil as electric charge in the power storage circuit when the coil changes from the operating state to the non-operating state. The operation of applying the storage voltage to the solenoid coil is started in response to the drive signal, but ends in the first embodiment when the storage voltage of the storage circuit decreases to a predetermined voltage higher than the DC power supply voltage. Further, in the second embodiment, the operation is terminated when a predetermined time elapses until the storage voltage of the storage circuit decreases to a predetermined voltage lower than the storage voltage but higher than the DC power supply voltage. Accordingly, in any of the embodiments, the high storage voltage of the power storage circuit is applied to the solenoid coil for a short time at the start of its operation, so that a steep rising current is provided in the solenoid coil, and Part of the charge remains in the circuit without being discharged. Thus, each of the second
Voltage application circuit applies a voltage to the solenoid coil based on the storage voltage of the power storage circuit, so that the voltage of the power storage circuit after operating the solenoid coil can always be maintained at a voltage higher than the DC power supply voltage. . Therefore, when the energy in the solenoid coil is recovered when the solenoid coil is deactivated thereafter, the energy is recovered using a voltage higher than the DC power supply voltage, so that the current in the solenoid coil is recovered. The fall becomes steep. When a cathode of a diode is connected to one end of the solenoid coil and an anode of the diode is connected to a ground potential terminal or a high potential terminal of a DC power supply,
When the energy in the solenoid coil is recovered, the above operation can be effectively realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a solenoid valve driving circuit according to the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a solenoid valve drive circuit according to the present invention.
This is applied to a fuel injection pump as shown in FIG. First, FIG.
The fuel injection pump and its solenoid valve will be described with reference to FIG. A cam plate 23 is connected to a drive shaft 22 rotatably disposed in a casing 21 of the fuel injection pump 20 via a known coupling.
A cam surface formed on the outer peripheral portion of the cam plate 23 is in contact with a roller 25 supported by a roller ring 24, and periodically moves back and forth in the axial direction of the shaft as the drive shaft 22 rotates. As a result, the plunger 27 in the cylinder 26 moves back and forth together with the cam plate 23. When the plunger 27 advances, the fuel in the pressure chamber 28 formed at the tip of the plunger 27 is compressed, and the injection valve 31 passes through the distribution port 29 and the distribution flow path 30. At the time of retreat, and through the suction passage 32 and the suction group 33, the low pressure chamber 3
The fuel in 4 is introduced into the pressure chamber 28. A pressure chamber passage 35 extending upward from the pressure chamber 28 is connected to a solenoid valve 36 and communicates with the low pressure chamber 34 through a passage 37 in the solenoid valve 36 and a low pressure passage 38.

An electronic control unit 39 provided outside the fuel injection pump 20 is constituted by a microcomputer or the like for executing a known fuel injection control, and includes a tooth profile of a signal rotor 40 provided on the drive shaft 22. Is detected by the pickup 41, a cylinder discrimination signal and an engine speed signal are input, and various state signals for fuel injection control such as an accelerator opening signal and an engine cooling water temperature signal are input from various parts of the engine. The control device 39 determines the optimal fuel injection timing and fuel injection amount based on each of the state signals, and supplies a control signal to the solenoid valve driving circuit 100. As a result, the solenoid coil 42 in the solenoid valve 36 is operated to control the valve opening / closing operation of the needle valve 43 in the solenoid valve 36, so that an appropriate fuel injection amount according to the engine operating state from the injection valve 31 is obtained. Given.

Next, the solenoid valve driving circuit 100 according to the present invention.
Will be described with reference to FIG. FIG. 1 shows an electromagnetic valve drive circuit 100 including a solenoid coil in the electromagnetic valve for easy understanding. This solenoid valve drive circuit 100 includes a battery power supply unit 110 for supplying a voltage V _B of the battery to the solenoid coil 42 of the solenoid valve, the charging voltage supply for supplying a power storage voltage of the capacitor 123 to the solenoid coil 42 Part 12
0, and each of these supply units 110, 120
The voltage is applied to the solenoid coil 42 in response to the drive signal from the electronic control device 39 of FIG.

[0017] In this electromagnetic valve driving circuit 100, one end of the solenoid coil 42 is connected via a diode 113 to the transistor 111 supplies the battery power V _B, the transistor 121 supplies a charging voltage of the capacitor 123 diode 124 are connected. Further, one end of the solenoid coil 42 is also connected to a ground potential terminal via a diode 125. The other end of the solenoid coil 42 is connected to a ground potential terminal via a transistor 114 driven by a drive signal, and is also connected to a capacitor 123 via a diode 126.

The capacitor 123 includes the solenoid coil 4
When the diode 2 changes from the operating state to the non-operating state,
It is charged by recovering the energy in the solenoid coil through 26. Note that the capacity of the capacitor 123 is appropriately determined by the resistance component and the inductance component of the solenoid coil 42. At this time, if the capacity of the capacitor is too small, the charging voltage becomes high, so that the cost of the elements in each part of the circuit increases, and if the capacity is too large, the difference between the voltages at the time of charging and discharging the capacitor becomes small. It is necessary to consider that. In this embodiment, the capacity of the capacitor 123 is, for example, on the order of 0.5 μF to 1 μF in consideration of a comparison operation in the voltage comparator 129 described below.

In the solenoid valve driving circuit 100, the high potential terminal of the capacitor 123 is connected to the ground potential terminal through the resistors 127 and 128, and the voltage of the capacitor 123 is divided and detected by using these resistors. You. A comparator 129 is connected to a connection point a between the resistors 127 and 128.
Is connected, and the comparator 129 compares the voltage of the capacitor at the connection point a divided by the resistor with the reference voltage V _{R. When the} voltage at the connection point a is higher than the reference voltage V _R , The potential signal is output to AND gate 130. The reference voltage V _R is set to a predetermined voltage value the charging voltage is less than greater than the voltage V _B of the battery Kodensa when recovered energy in the solenoid coil 42. The AND gate 130 that inputs the comparison result signal from the comparator 129 and the drive signal outputs a signal to the transistor 122 that drives the transistor 121.

Next, the operation of the solenoid valve constructed as described above will be described.
The operation of the circuit 100 is described with reference to FIGS.
I do. The plunger 27 shown in FIG.
When the process starts, the time t in FIG. ₁Electronic control unit 39
Then, a high-potential drive signal is output. With this, the solenoid valve
In the drive circuit 100, a transistor responds to a drive signal.
114 and transistor 112 are turned on,
When the transistor 111 is turned on, the solenoid
The voltage of the battery is applied to the coil 42. On the other hand
The driving signal is also supplied to one input terminal of the AND circuit 130.
Supplied. At this time, the capacitor 123
Is charged to about 100V, for example.
If the other input terminal of the AND circuit 130 is
In the state where the high potential signal is given from the detector 129
Therefore, the AND circuit 130 responds to the drive signal to
Output a potential signal and turn on the transistor 122 to turn on the transistor.
The transistor 121 is driven. As a result, transistor 1
21, the diode 124 and the transistor 114
The voltage of the capacitor 123 passes through the solenoid coil
42.

The solenoid coil 42 In this case, first the charging voltage of the high capacitor 123 than the battery voltage V _B is applied. Thus, since the current in the solenoid coil 42 becomes to rise rapidly, the needle valve 43 in Figure 2, reached its operating region at the time t ₂ in FIG. 3, the rapidly valve in response to said drive signal Can be closed. However, in the present invention, the period during which the voltage of the capacitor 123 is applied to the solenoid coil 42 is only a short time after the start of the operation of the solenoid coil 42, and the charging voltage of the capacitor 123 becomes, for example, It is the time required to decrease from about 100V to about 60V. This is realized by the fact that the charging voltage of the capacitor 123 is detected at the connection point a and is determined by the comparator 129 as described above. That is, the reference voltage V _R corresponding to when the voltage of the capacitor becomes approximately 60V
By comparator 129 compares the voltage of the connection point a, the comparator 129 outputs a low potential signal to the AND circuit 130 when the voltage of the connection point a is equal to or less than the reference voltage V _R with a series of the transistors 121 and 122 off, which thereafter is realized by applying a battery voltage V _B to the solenoid coil 42 through the transistor 111. Thus, the capacitor 123, even after the solenoid coil 42 is completed operation, is maintained at a voltage higher than the battery voltage V _B.

Thereafter, at time t _{3 in} FIG. 3, the pressure feed stroke of the plunger 27 starts, and fuel injection from the injection valve 31 in FIG. 1 starts. The drive signal from the electronic control unit 39 at time t ₄ when the jetting a predetermined injection quantity is turned off, so that all series transistors 111,112,114 turned off in this solenoid valve driving circuit. At this time, the current trying to keep flowing through the solenoid coil 42 is:
The capacitor 123 flows from the ground potential terminal through the diode 125, the solenoid coil 42, and the diode 126 to the capacitor 123. As a result, the capacitor 123 is charged to about 100V. In this case the inclination of the current flowing from the solenoid coil 42 to capacitor 123 "di / dt" is the capacitor 123 now to earlier is charged to approximately _{60V, d i / d t =} -V c (t) / L (Where L is the inductance of the solenoid coil 42,
V _c achieves a large value from the relationship between the voltage) of the capacitor 123. Accordingly, the time during which current flows from the solenoid coil 42 to the capacitor 123 can be reduced, and the drive signal is turned off and the solenoid coil 4
2 can be quickly brought into the non-operation state, and the needle valve 27 in FIG. 2 can be quickly opened. In this solenoid valve driving circuit, the anode of the diode 125 is
It may be connected to a high potential terminal of the battery instead of the contact potential terminal. Further, the other side of the capacitor 123 may be connected to a certain reference potential point instead of the ground potential terminal.

Further, the second embodiment of the solenoid valve drive circuit according to the present invention
The embodiment will be described with reference to FIG. In addition, the first
The same reference numerals are given to the portions corresponding to the embodiment of FIG. The solenoid valve driving circuit 140 has a configuration that is partially common to that of the first embodiment.
A buffer 141 for inputting a driving signal from the electronic control circuit 39 to 0, a differentiating circuit 144 including a resistor 143 and a capacitor 142, and an AN for inputting a signal from the differentiating circuit 144 and the driving signal to drive the transistor 122
And a D circuit 145. Thus, when the solenoid valve driving circuit 140 activates the solenoid coil in response to the driving signal, the solenoid valve driving circuit 140 supplies a high voltage of the capacitor 123 for a time corresponding to the time constant of the differentiating circuit 144 in the initial stage. I have to. That is, when the drive signal is given from the electronic control circuit 39, transistors 111 and 112 are turned on, while the solenoid coil 42 voltage V _B of the battery is enabled application, on the one hand at the same time, the drive signal Since the signal is supplied to the differentiating circuit 144 through the AND circuit 145 and the buffer 141, the output of the AND circuit 145 becomes a high potential for the time of the time constant determined by the capacitor 142 and the resistor 143 of the differentiating circuit 144. When turned on, a high voltage of the capacitor 123 is applied to the solenoid coil 42. The time constant is set to the time required for the charging voltage of the capacitor 123 to decrease from, for example, about 100 V to about 60 V when the solenoid coil is activated.

With this configuration, the solenoid valve drive circuit 140 sets the time for applying the high voltage of the capacitor 123 to the solenoid coil 42 to a small value, thereby providing the drive circuit of the first embodiment with the drive circuit of the first embodiment. Although the same operation is realized, the present solenoid valve driving circuit has the following advantages as compared with the solenoid valve driving circuit of the first embodiment. In the first embodiment, the electric charge stored in the capacitor 123 slightly flows into the ground potential terminal through the resistors 127 and 128, so that the energy stored in the capacitor 123 is slightly consumed. This does not occur in the embodiment. Therefore, the energy in the solenoid coil 42 can be effectively used, and the range of selection of the solenoid coil 42 applied to the solenoid valve drive circuit 140 can be expanded.

[0025]

As described above, according to the present invention, when the solenoid coil in the solenoid valve is operated, the driving of the solenoid coil is supported in a high storage voltage range in accordance with the storage voltage of the storage circuit, and the solenoid coil is moved from the operating state. When the non-operation state is set, the energy in the solenoid coil is effectively recovered by using the high storage voltage remaining in the storage voltage, so that the rise of the current flowing in the solenoid coil when the solenoid coil is activated is quickly increased. In addition to being able to be steep, the fall of the current flowing in the solenoid coil when the solenoid coil is in the non-operation state can be made steep immediately, and a series of such operations can be quickly realized after the engine is started. Such a solenoid valve drive circuit can be provided at low cost. Thereby, the responsiveness of the injection valve in the fuel injection control can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a solenoid valve drive circuit according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a fuel injection pump to which the solenoid valve drive circuit according to the present invention can be applied.

FIG. 3 is a time chart showing a signal state in each part of the solenoid valve driving circuit of FIG. 1;

FIG. 4 is a circuit diagram showing another embodiment of the solenoid valve driving circuit according to the present invention.

FIG. 5 is a circuit diagram showing an example of a conventional solenoid valve driving circuit.

FIG. 6 is a time chart showing signal states in various parts of the drive circuit of FIG. 5;

FIG. 7 is a circuit diagram showing another example of a conventional solenoid valve driving circuit.

[Explanation of symbols]

42: solenoid coil 100: solenoid valve driving circuit according to the present invention 110: battery power supply unit 111, 112: transistor for applying battery power 120: charging voltage supply unit 121, 122: transistor for applying capacitor voltage 123: solenoid coil 129 ... Comparator 130 ... AND circuit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Moriyasu Goto 14 Iwatani, Shimowasumi-cho, Nishio-shi, Aichi Prefecture Inside the Japan Automobile Parts Research Institute (72) Inventor Takio Tani 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nippon Denso (56) References JP-A-57-49059 (JP, A) JP-A-2-84813 (JP, A) JP-A-60-187006 (JP, A) JP-A-1-318740 (JP, A) A) JP-A-61-126349 (JP, A) JP-A-6-299890 (JP, A) JP-A-60-148833 (JP, A) Japanese Utility Model Showa 63-146273 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) F02D 41/00-45/00 F02M 41/00-69/00 F16K 31/06 H01F 7/18

Claims (3)

(57) [Claims] A first voltage application circuit for applying a DC power supply voltage to a solenoid coil in response to a drive signal for driving an electromagnetic valve; and a first voltage application circuit connected to the solenoid coil, wherein the solenoid coil is in a non-operating state. A power storage circuit that stores the energy in the solenoid coil at a voltage higher than the DC power supply voltage when the power supply voltage is higher than the DC power supply voltage; An electromagnetic valve drive circuit having a voltage application circuit, wherein the second voltage application circuit compares a voltage of the power storage circuit with a predetermined voltage lower than the storage voltage and higher than the DC power supply voltage; A circuit that applies the voltage of the power storage circuit to the solenoid coil in response to the drive signal only when the voltage of the power storage circuit is higher than the predetermined voltage. Electromagnetic valve driving circuit, characterized by that example. 2. A first voltage application circuit for applying a DC power supply voltage to a solenoid coil in response to a drive signal for driving an electromagnetic valve, wherein the first voltage application circuit is connected to the solenoid coil, and the solenoid coil is turned off. A power storage circuit that stores the energy in the solenoid coil at a voltage higher than the DC power supply voltage when the power supply voltage is higher than the DC power supply voltage; An electromagnetic valve drive circuit having a voltage application circuit, wherein the voltage of the power storage circuit is higher than the DC power supply voltage from the time when the second voltage application circuit applies the voltage of the power storage circuit to the solenoid coil. A circuit for setting a time until the voltage drops below a high predetermined voltage, and the voltage of the power storage circuit is set in response to the drive signal. Electromagnetic valve driving circuit characterized by comprising a circuit for applying only while. 3. The diode according to claim 1, wherein a cathode of a diode is connected to one end of the solenoid coil, and an anode of the diode is connected to a ground potential or a high potential terminal of the DC power supply. The described circuit.