JPS6380038A - Solenoid valve drive circuit - Google Patents

Abstract

PURPOSE:To make responsiveness in a solenoid valve improvable in a way of making transition to a backward current of an solenoid valve coil speedier and without increasing cost and structure, by installing a counter-electromotive force generating coil, a side from the solenoid valve coil. CONSTITUTION:A current out of a current supply unit 9 is made to flow into a solenoid valve coil 1 in advance by a transistor 7. Simultaneously with intercepting this current, another current so far made to flow into a counter- electromotive force generating coil 2 installed separately from the solenoid valve coil 1 by a transistor 8 from a constant-current device 3 is cut off. At this time, counter-electromotive force to be produced in this counter- electromotive forge generating coil 2 is reversely impressed on the solenoid valve coil 1 via a thyristor 4. Then, a reverse current loop is constituted as long as the requisite time by a reverse current duration controlling transistor 6, whereby a backward current is made to flow into the solenoid valve coil 1 and residual magnetic flux inside a core is quickly attenuated. With this constitution, responsiveness in a fuel injection controlling solenoid valve 15 is improved.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention is a solenoid valve for fuel injection control of a diesel engine or a gasoline engine, by immediately passing current in the opposite direction to the solenoid valve coil after the energization is stopped. The present invention relates to a solenoid valve drive circuit that promptly eliminates magnetic flux after energization is stopped, improves the responsiveness of the solenoid valve, realizes accurate fuel injection control, and enables adaptation to high-speed rotation.

"Conventional technology" Solenoid valves for fuel injection control in diesel engines are
Accurate control becomes difficult, especially at high rotations, due to the delay in response after energization is stopped. There are two types of response delay after energization is stopped: mechanical delay and magnetic delay. Mechanical delay is determined by the mass spring of the solenoid valve moving part, and magnetic delay This delay is due to residual magnetic flux in the internal core of the solenoid valve after the externally supplied current is completely cut off. This residual magnetic flux is generated because eddy currents continue to flow inside the core even after the external current is cut off.

One possible way to reduce the magnetic delay is to reduce eddy currents by layering the core, etc., but this increases the cost. It was thought that the flow would speed up the attenuation of the vortex flow.

Conventionally, as a method of passing a reverse current,
There is a method, as disclosed in Japanese Patent No. 33, in which the power supply voltage is applied in the opposite direction when the solenoid valve is closed, but it takes time to shift to the reverse current, and a sufficient magnetic flux extinction effect cannot be obtained. Also,
As described in Japanese Patent Publication No. 57-27301, there is a method of charging a capacitor to a high voltage and then applying that high voltage to the solenoid valve coil in the opposite direction, but this method not only requires a complicated circuit configuration but also requires high withstand voltage and large capacity. capacitor is required,
There were problems in terms of cost and size.

"Problems to be Solved by the Invention" The present invention has been made to solve one or more problems, and it is possible to quickly transition to reverse flow, and to improve the response of a solenoid valve without increasing cost or size. An object of the present invention is to provide a solenoid valve drive circuit that can improve performance.

"Means for Solving the Problem" For the above purpose, according to the present invention, a current supply device connected in series to a solenoid valve coil for attracting a movable part of a solenoid valve and maintaining the attracted state. A current is further caused to flow through a first transistor connected in series to the solenoid valve coil, and at the same time, this current is cut off, and at the same time, this reverse electromotive force generation coil is provided separately from the solenoid valve coil. The current flowing from the constant current device connected in series to the electromotive force generation coil and further by the second transistor connected in series to the counter electromotive force generation coil is interrupted, and at this time, the counter electromotive force generation A first transistor connected between a connection point between the back electromotive force generating coil and the second transistor, and a connection point between the electromagnetic valve coil and the first transistor. A reverse current is applied to the electromagnetic valve coil through a thyristor, and then a reverse current loop is formed by a semiconductor switch element connected to a connection point between the electromagnetic valve coil and the current supply device for a necessary time. , there is provided an electromagnetic valve drive circuit characterized in that a reverse current is caused to flow through the electromagnetic valve coil to rapidly attenuate residual magnetic flux inside a core of the electromagnetic valve coil.

"Operation" According to the above configuration, before the current flowing through the solenoid valve coil is cut off, current is passed through the back electromotive force generation coil provided separately from the solenoid valve coil, and the back electromotive force is generated. Using the high-voltage back electromotive force generated in the electromagnetic valve coil, the direction of the current in the solenoid valve coil is instantly reversed, and the transition to reverse current is accelerated.

r Embodiment According to the first embodiment of the present invention, the semiconductor switching element is a third transistor, and according to this embodiment, it is possible to accurately control the period during which a reverse current loop is formed. It has the advantage of being possible.

According to a second embodiment of the present invention, the semiconductor switch element is a diode, and this embodiment has the advantage of simplifying the circuit configuration.

According to the third embodiment of the present invention, a second connection point between the counter electromotive force generation coil and the second transistor and a connection point between the electromagnetic valve coil and the current supply device is provided. A thyristor is provided, and at the time of starting energization to the electromagnetic valve coil, a back electromotive force generated in the back electromotive force generating coil is applied to the electromagnetic valve coil via the second thyristor, and a current with a steep rise is generated. There is provided an electromagnetic valve drive circuit according to claim 1, characterized in that the electromagnetic valve drive circuit is characterized in that the electromagnetic valve drive circuit allows the flow of

According to this aspect, there is an advantage that by passing a steeply rising current through the electromagnetic valve coil, the magnetic flux in the core of the electromagnetic valve coil can be rapidly raised, and the attraction can be accelerated.

"First Embodiment" FIG. 1 shows one end of a coil 1 of a solenoid valve 15 having a core 14 (hereinafter referred to as solenoid valve coil 1), showing a first embodiment of the present invention.
(referred to as a positive example), through a current supply device 9 including a transistor 11 capable of internally interrupting the current supply path, and a protection diode 5 of the current supply device 9,
It is connected to the positive side of the power supply 10. Solenoid valve coil 1
The other end (hereinafter referred to as the negative side of the electromagnetic valve coil) is connected to the negative side of a power source 10 via a driving transistor 7. One end of a back electromotive force generating coil 2 provided separately from the electromagnetic valve coil 1 is connected to the positive side of a power source 10 via a constant current device 3. The other end (hereinafter referred to as the negative side of the back electromotive force generation coil 2) is connected to the negative side of the power source 10 via the back electromotive force generation transistor 8. Thyristor 4 is a solenoid valve coil 1
and the negative side of the counter electromotive force generating coil 2. The plus side of the electromagnetic valve coil 1 is connected to the minus side of a power source 10 via a reverse current duration control transistor 6. Further, from the control circuit 12 which calculates the signals of the diesel internal combustion engine 13, a signal a is sent to each transistor 6.7, 8.11 and the thyristor 4.

a, b, c, and 4 are now introduced.

For example, it is assumed that when the electromagnetic valve coil 1 is energized, the electromagnetic valve 15 is opened, and when the electromagnetic valve coil 1 is de-energized, the electromagnetic valve 15 is closed.

Next, the operation of the circuit connected as described above will be explained. There are four control signals, a, a, b, and c, which are calculated by the control circuit 12 according to the operating state of the internal combustion engine 13. As shown in FIG. 3, the signals a,
a is the energization signal to the solenoid valve coil 1, and the signal is:
After the signal a rises, it rises at the calculated time and falls in synchronization with the fall of the signal a. Also,
Signal C rises in synchronization with the fall of signal a,
It falls after the calculated time. When the solenoid valve drive signal a rises, the transistor 7 is turned on, and the transistor 11 of the current supply device 9 is also turned on, a current supply path is formed, and a current determined by the current supply device 9 flows through the solenoid valve coil 1. . For example, as shown in Fig. 2, this current is a large current that rapidly attracts the current, and then becomes a constant current that maintains the attracting state. The transistor 8 is turned on, and a current determined by the constant current device 3 flows through the back electromotive force generating coil 2.Next, at the same time as the signals a and b fall, the reverse current duration control signal C rises, and the thyristor 4 A trigger is applied to the gate. Transistor 7.8 is turned off, and transistor 6 and thyristor 4 are turned on. Then, the current supply path of the current supply device 9 is cut off, and the back electromotive force generated in the back electromotive force generation coil 2 is applied to the solenoid valve coil 1 via the thyristor 4, and as a result, the reverse current duration control is performed. A reverse current flows through the electromagnetic valve coil 1 through the transistor 6. When the reverse current duration control signal C falls, the transistor 6 is turned off, the reverse current is cut off, and the thyristor 4 is turned off.

In this way, by instantly reversing the direction of the current in the solenoid valve coil 1 and continuing to flow the reverse current for a certain period of time, the eddy current inside the core 14 of the solenoid valve coil 1 is quickly attenuated, and the magnetic flux is This speeds up the extinction and improves the responsiveness of the solenoid valve 15.

Moreover, an excessive reverse current may generate magnetic flux in the opposite direction in the solenoid valve coil 1 and generate an attractive force, which may worsen the response. However, according to this embodiment, reverse current duration control is possible. Depending on the pulse width of the signal C, it is possible to easily obtain the optimum reverse current for the various solenoid valves 15.

"Second Embodiment" FIG. 4 shows a second embodiment. In this embodiment, in place of the reverse current duration control transistor 6 provided in FIG. A diode 16 is connected between the positive side of the power supply 10 and the positive side of the power supply 10, and the configuration is simpler than that of the circuit shown in FIG. In the circuit of FIG. 4, the duration of the reverse current is transiently determined by the energy stored in the back electromotive force generating coil 2.

"Third Embodiment" FIG. 5 shows a third embodiment, in addition to the circuit shown in FIG. , a second iris register 17 is provided, and the solenoid valve 15 after the energization of the magnetic valve coil 1 is stopped.
This improves not only the responsiveness of the current flow, but also the responsiveness at the start of energization. In this embodiment, the current supply π9 only needs to be a constant current that maintains the attracting state. The operation of the circuit shown in FIG. 5 will be explained below with reference to FIG. 6. Before the driving transistor 7 is turned on by the signal a, the back electromotive force generation transistor 8 is turned on by the signal A, and a current is caused to flow through the back electromotive force generation coil 2 by the constant current device 3. 8.Next, when the driving transistor 7 is turned on by the signal a, the back electromotive force generation transistor 8 is turned off by the signal a, and the second thyristor 17 is turned on, the back electromotive force generation coil 2 generates a back electromotive force. An electromotive force is applied to the positive side of the solenoid valve coil 1, and a current with a steep rise flows through the solenoid valve coil 1.
5 responds quickly. At this time, when the back electromotive force generating transistor 8 is turned on again by the signal S, the thyristor 17 is turned off, and the following operation is similar to that of the circuit shown in FIG. 1.

"Fourth Embodiment" FIG. 7 shows a fourth embodiment. This embodiment is used to improve the responsiveness of a plurality of electromagnetic valves 15a, 15b, . . . 15n. The operation of this circuit, as shown in FIG. 8, is similar to the operation of the first embodiment shown in the timing chart of FIG.

"Effect" As described above, since the solenoid valve drive circuit of the present invention has the above configuration, it uses the high voltage back electromotive force generated in the back electromotive force generating coil to direct the current in the electromagnetic valve coil. This has the excellent effect of being able to reverse the current flow when the eyelids, speeding up the transition to the reverse current, and improving the responsiveness of the solenoid valve without increasing cost and size.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the first embodiment of the present invention, Fig. 2 is a waveform diagram showing the current flowing through the solenoid valve coil, and Fig. 3 is a circuit diagram showing the first embodiment of the present invention.
A timing chart showing the signals and current waveforms of each part in the embodiment, FIG. 4 is a circuit diagram showing the second embodiment, FIG. 5 is a circuit diagram showing the third embodiment, and FIG. 6 is a circuit diagram showing the third embodiment. FIG. 7 is a circuit diagram showing the fourth embodiment, and FIG. 8 is a timing chart of the fourth embodiment. 100. Solenoid valve coil 210. Coil 301 for generating back electromotive force. Constant current device 411. Thyristor 61. , reverse current duration control transistor 711. Drive transistor 811. Back electromotive force generation transistor 919. Current supply device 12. ,,control circuit 13,
,,Diesel internal combustion engine 15, ,Fuel injection control solenoid valve 16, ,Diode 17゜1. Second thyristor Fig. 1 Fig. 212I Fig. 3 Fig. 4 1p, 5121 Fig. 6 Fig. 7 (2I Fig. 8

Claims (4)

[Claims] (1) In a drive circuit that is activated by a signal from a control circuit and drives one or more fuel injection control solenoid valves of an internal combustion engine, to attract the movable part of the solenoid valve and maintain the suction state. A current from a current supply device connected in series to the solenoid valve coil is caused to flow through a first transistor connected in series to the solenoid valve coil, and at the same time, when this current is cut off, the current is supplied to the solenoid valve coil. is applied to a separately provided counter electromotive force generating coil from a constant current device connected in series to the counter electromotive force generating coil, and further by a second transistor connected in series to the counter electromotive force generating coil. the back electromotive force generated in the back electromotive force generating coil at a connection point between the back electromotive force generating coil and the second transistor;
A reverse voltage is applied to the electromagnetic valve coil through a first thyristor connected between the connection point of the electromagnetic valve coil and the first transistor, and then the current is applied to the electromagnetic valve coil for a necessary time. A reverse current loop is formed by a semiconductor switch element connected to a connection point of the device, thereby causing a reverse current to flow through the solenoid valve coil, thereby rapidly attenuating the residual magnetic flux inside the core of the solenoid valve coil. Solenoid valve drive circuit. (2) The electromagnetic valve drive circuit according to claim 1, wherein the semiconductor switch element is a third transistor. (3) The electromagnetic valve drive circuit according to claim 1, wherein the semiconductor switch element is a diode. (4) A second thyristor is provided between a connection point between the back electromotive force generation coil and the second transistor and a connection point between the electromagnetic valve coil and the current supply device, and The electromagnetic valve according to claim 1, characterized in that, at the start of energization, a back electromotive force generated in the back electromotive force generating coil is applied to the electromagnetic valve coil via the second thyristor. drive circuit.