JPS6315728B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid high-speed drive circuit using a chiyoke coil, which uses the constant current characteristics of the chiyoke coil and the current switching characteristics of a transistor to make the rising characteristics of the solenoid coil current steeper. The purpose is to improve the operating characteristics of solenoid coils.

The method of converting electrical signals into mechanical movement using a solenoid is widely used because it is inexpensive and has a simple mechanical structure. When using solenoid coils, there are two common methods: mechanical operation using a switch, and controlling the solenoid coil current using the voltage of a signal source using the switching characteristics of a transistor, but the latter method is particularly sensitive to artificial operation. Because the solenoid can be operated without the need for a switch, it is used when a large number of operations are to be performed within a certain period of time. However, this system has the disadvantage that the solenoid coil has inductance, which prevents the current flowing through the coil from changing rapidly, and that the rise characteristics when electromagnetic attractive force is generated are poor.

FIG. 1 shows a conventional solenoid drive circuit, which is a resistance drive type having an additional resistor _R1 . When DC (12V) from battery B is supplied to this circuit using a switch SW using a transistor or the like, as shown in the current characteristic diagram in Figure 2, the signal S flows through the solenoid coil SC even if it rises as shown by the dotted line. As shown by the solid line curve i, the current approaches a constant value with a so-called first-order lag characteristic.In other words, the time constant _t1 representing the rising speed of the current at this time is expressed as L/R.
To shorten t ₁ , you can increase the value of the additional resistance R ₁ , but if you do so, the current value will decrease and the magnetic force will decrease, making the movement of the actuator etc. attracted by the solenoid worse. . Therefore, there is a natural limit to the speed at which the current can rise,
Furthermore, reducing L also similarly reduces the magnetic force.

In the past, in order to improve this kind of delay, there was a tendency to use a higher voltage at startup, but especially when using battery voltage in automotive applications, it is necessary to add a power supply device to boost the voltage. This has the disadvantage of increasing the complexity and cost of the circuit, as well as increasing the power loss within the circuit.

In view of the above points, the present invention utilizes the constant current characteristics of the chiyoke coil and the current switching characteristics of the transistor to make the rise characteristics of the solenoid coil current steeper. This makes it possible to improve the operating characteristics of the solenoid.

Embodiments of the present invention will now be described based on the drawings.

Figure 3 is a basic circuit diagram of the present invention, where B is a battery, L _C is a choke coil, CSW is a transistor-based changeover switch, R is a resistor, and _R1 is an additional resistor.
SC is a solenoid coil, and the circuits a ₁ and a ₂ on both sides to be switched have approximately equal current values.

In the above circuit, if the current currently flowing on the _a1 side is switched to the _a2 side by the switch CSW, the current change will be very large as shown in the curve _i2 shown on the right side of the switching point O in the current characteristic diagram in Figure 4. The change will be small. That is, the left side of the switching point O is the current i ₁ before switching, and since the inductance of the chain coil L _C has the property of preventing changes in the current, the current value immediately after switching is almost the same value as i ₁ , and after that the current value is slightly It becomes a steady value only by falling to .

In the conventional drive system described above, the current value at the time of switching rises gently from the switching point O, as shown by the chain line in the figure, but in the present invention, it suddenly starts from a certain value, so the attraction force required for the actuator is lower than that of the conventional drive system. This occurs in an extremely short time compared to the above method.

FIG. 5 is a circuit diagram showing an embodiment of the present invention, in which transistors Tr1 and Tr2 and inverters 1 and 2 inserted into their signal input circuits are turned on and off alternately.
A solenoid coil 3 and an additional resistor 4 are connected to one side of a pair of switching circuits that are turned off, and a resistor 5 is connected to the other side, and both circuits are connected to a power line 7 in which a switch coil 6 is inserted in series on the power source side. They are connected in parallel, and in this case both times are set to approximately the same current value.

In the circuit of the present invention configured as described above, when the input signal of inverter 1 is set to high level, the output of inverter 1 becomes low level, and the transistor
Tr1 is in the OFF state and no current flows through the solenoid coil 3, but at the same time, the output of the inverter 2 becomes high level, so the transistor Tr2 is in the ON state, and current flows through the choke coil 6, the resistor 5, and the transistor Tr2. .

In this state, if the input signal is set to low level, the outputs of inverters 1 and 2 will be reversed, so the transistor
The operating states of Tr1 and Tr2 are also reversed, and the transistor
At the same time as Tr1 turns on, transistor Tr2 turns on.
When the current is turned OFF, the current flowing through the coil 6, the resistor 5, and the transistor Tr2 changes its path to the additional resistor 4, the solenoid 3, and the transistor Tr1. As described above, the current flowing through the coil 3 has a very fast rise.

When a solenoid was actually driven using a conventional circuit and a circuit according to the present invention, the rise time was reduced by 30% with the circuit according to the present invention.

FIG. 6 shows an embodiment in which solenoid coils are inserted into both of a pair of switching circuits, and the two solenoids are operated in a push-pull manner. That is, a push solenoid coil 3a is inserted into one of the switching circuits, and a pull solenoid coil 3b is inserted into the other switching circuit in place of the resistor 5 shown in FIG. Note that 8 is a current limiting resistor.

This circuit is an extremely simple circuit that can effectively apply the principle of the present invention to two solenoid coils.

Figure 7 shows an embodiment in which the steady-state value of the current flowing through the solenoid coil is reduced, and a capacitor 9 is provided in parallel with the additional resistor 4 shown in Figure 5. has a higher resistance than the resistor 4 above. The capacitor 9 shows almost no resistance against rapid voltage changes, that is, the impedance is zero, so even if the value of the resistor 4' is high, the resistance is zero, and as time passes, the capacitor 9 and the resistor 4' Since the impedance of the parallel circuit portion approaches the value of resistor 4', the magnitude of the current when the current value becomes constant is smaller than that of the conventional circuit shown in FIG.

FIG. 8 is a waveform diagram of an oscillogram obtained by actually measuring changes in current and valve stroke when a solenoid valve is driven by the conventional circuit and the circuit shown in FIG. 7 of the present invention. The circuit shown in Figure B is the circuit according to the present invention.

As is clear from this figure, in figure A, the valve moves by 0.2 mm for the stroke, but in the opening direction it is approximately
1.5 milliseconds, and approximately 0.9 milliseconds in the closing direction, whereas in figure B, the same stroke is 0.2 mm.
Approximately 1 millisecond in the opening direction and approximately 0.6 millisecond in the closing direction.
The response speed is improved by 30% compared to A in the same figure, and the rise of the current waveform is also extremely faster compared to A in the same figure. Furthermore, due to the addition of the capacitor, the steady-state value of the current is 1.6 amperes in figure A, while it is around 0.4 amperes in figure B.

In this way, by using a capacitor and reducing the steady-state value of the current, the force that holds the actuator in position can be reduced, so the actuator can return quickly after the current in the solenoid coil is cut off using a changeover switch. Even if it is used, there is almost no effect on the rise of the current, and only benefits are added.

As described above, the present invention connects a solenoid coil to one side of a pair of switching circuits that are turned on and off alternately by transistors, and connects a resistor to the other, or connects solenoid coils to both circuits. The circuit is connected in parallel to a power line having a chiyoke coil, and the constant current characteristics of the chiyoke coil and the current switching characteristics of the transistor are used to make the rise characteristics of the solenoid coil current steeper, making it different from conventional circuits of this type. As shown in the figure, the operating characteristics of the solenoid can be improved without increasing the voltage and the voltage remains low, thus achieving excellent effects such as enabling high-speed driving.

[Brief explanation of the drawing]

Fig. 1 is a conventional solenoid drive circuit diagram, Fig. 2 is a current characteristic diagram as above, Fig. 3 is a basic circuit diagram of a solenoid high-speed drive circuit using the inventive chiyoke coil, Fig. 4 is a current characteristic diagram as above, and Fig. 5 is a diagram of a conventional solenoid drive circuit. The figure is a circuit diagram showing the same embodiment as above, Figure 6 is a circuit diagram of push-pull operation as above, Figure 7 is a circuit diagram using a capacitor as above, and Figure 8 is an oscillogram waveform of the conventional circuit and the circuit of the present invention. It is a diagram. Tr1, Tr2...Transistor, 1,2...Inverter, 3,3a,3b...Solenoid coil, 4...Additional resistance, 5...Resistor, 6...Chiyoke coil, 7...Power line.

Claims (1)

[Claims] 1. A solenoid coil is connected to one side of a pair of switching circuits that are turned on and off alternately by a transistor, and a resistor is connected to the other side, or a solenoid coil is connected to both circuits, and both of these circuits are connected. A solenoid high-speed drive circuit using a chiyoke coil, characterized in that the circuit is connected in parallel to a power line having a chiyoke coil. 2. A chiyoke coil according to claim 1, characterized in that two solenoid coils are connected to both of a pair of switching circuits that are alternately turned on and off by transistors so as to operate in a push-pull manner. Solenoid high speed drive circuit.