JPH0770392B2 - DC solenoid drive method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for driving a DC solenoid that performs control (hereinafter referred to as duty control) for changing the ON time during a fixed period to control a target physical quantity. .

[Conventional technology]

Conventionally, a DC solenoid driving method of this type will be described with reference to FIGS. 2 to 4.

2 is a solenoid drive circuit diagram, FIG. 3 is a circuit diagram of the solenoid drive circuit of FIG. 2 having a constant current chopper control function, and FIGS. 4 (a) and 4 (b) are timings of the DC solenoid drive method. It is a chart.

That is, as shown in FIG. 2, this solenoid drive circuit is
Duty command means 1 for outputting command 1 for holding excitation and command 2 for overexcitation, first and second transistors 4 and 5 connected via resistors 2 and 3, and connected in parallel to the first transistor 4. The solenoid 6 and the Zener diode 7, the DC power source 8 connected to the solenoid 6, and the resistor 9 interposed between the first and second transistors 4 and 5.
It consists of and.

The solenoid drive circuit shown in FIG. 3 includes a duty command means 1 for outputting commands 1 and 2 and a first transistor 4 connected to the duty command means 1 via a resistor 10.
And a Zener diode 7 and a third transistor 11 connected in parallel to the first transistor 4 via a resistor 2.
A DC power source 8 connected to the Zener diode 7 via a diode 12 and the duty command means 1.
A second transistor 5 connected in sequence through an AND element 13, a monostable flip-flop 14 and a resistor 15, and a reference voltage generator 16 also connected to the duty command means 1.
A current detection resistor 17 and a comparator 18 connected in parallel to the second transistor 5, and one end of the third transistor
11 is connected to the second transistor 5, and the other end is composed of a solenoid 6 connected between the diode 12 and the DC power source 8. The comparator 18 is the AND circuit.
The reference voltage generator 16 is connected to the element 13 and the reference voltage generator 16, respectively, and the reference voltage generator 16 includes a power supply 16a having a reference voltage V _r1 corresponding to a holding current, a power supply 16b having a reference voltage V _r2 corresponding to an overexciting current, and a switch. Has 16c.

Next, the operation of the solenoid drive circuit will be described.

That is, as shown in FIG. 4 (a), the duty command means 1
Outputs command 1 and command 2 at the same time, and each base resistance 2
Turn on the first and second transistors 4 and 5 through
Since the state is set, the overexcitation current flows in the circuit of the DC power supply 8, the solenoid 6 and the first transistor 4 for T ₂ time (overexcitation mode). After that, the command 2 disappears, the first transistor 4 is turned off, and the solenoid current flows through the path of the DC power source 8, the solenoid 6, the resistor 9 and the second transistor 5 (holding mode). This current is a value smaller than the above-described overexciting current by a value determined by the value of the resistor 9, and is set to a value required to hold the state of the solenoid valve, which is called a holding current. The command 1 is turned off at T ₁ time corresponding to the duty value, and the second transistor 5 is also turned off. I is the solenoid current immediately before the second transistor 5 is turned off.
₀ , the inductance of the solenoid 6 is L, the resistance is r, the zener voltage of the zener diode 7 is V ₂ and the voltage of the DC power supply 8 is E, the second transistor 5 is turned off.
The relationship between the time t after the state is reached and the solenoid current i can be expressed by the following equation.

Therefore, the solenoid current flows through the path of the DC power source 8, the solenoid 6 and the Zener diode 7 until time T ₁ when i = 0 in the equation (2). The ON command time T ₂ of the command ₂ is equal to the overexcitation time T _EX , and is set to a value obtained by adding a predetermined amount to the time the solenoid valve operates. Further, as shown in FIG. 4 (b), when the duty value decreases and T ₁ <T _EX , the times T ₁ and T ₂ become equal and both transistors 4 and 5 are turned off at the same time.

Furthermore, in the solenoid drive circuit having the constant current chopper control function, first, when the command 1 and the command 2 are simultaneously output from the duty command means 1, the command 1 outputs the first command.
And the third transistors 4 and 11 are turned on, and the AND element 13
Is also High, the second transistor 5 is turned on, and the solenoid current flows through the path I of the DC power supply 8, the solenoid 6, the second transistor 5, and the current detection resistor 17. As the current flowing through the current detection resistor 17 increases, the inverting input terminal voltage of the comparator 18 increases, and eventually the reference voltage V _r2 of the power supply 16b in the reference voltage generator 16 selected by the output of the command 2 becomes higher than the reference voltage V _r2 . When it goes high, the output of comparator 18 goes low,
The output of the D element 13 is also low, and the second transistor 5 is off. Therefore, the solenoid current flows through the solenoid 6, the third transistor 11, the diode 12, and the path II of the solenoid 6. Output of AND element 13 falls (High → Low)
The output of the monostable flip-flop 14 is low for a certain period of time.
Since it is in the state, the second transistor 5 is turned off.
Then, there is no current flowing through the current detection resistor 17, and the output of the comparator 18 becomes High, but the AND element 1
The output of 3 remains Low. After the fixed time, the output of the monostable flip-flop 14 becomes High and the second transistor 5 is turned on, so that the solenoid current flows through the path I again. Hereinafter, the paths I and II are repeated until the command 1 becomes Low. However, as shown in Fig. 4 (a), command 2
Is turned off during the operation, the power supply 1 is turned on in the reference voltage generator 16.
The reference voltage V _{r1 of} 6a is selected, and the solenoid current becomes the holding current value. Next, when the command 1 is turned off, the first and second transistors 4 and 5 are turned off, and the third transistor
A current flows through the path II due to the action of 11 and the Zener diode 7, but this current becomes 0 after t ₁ time due to the attenuation as shown in the equations (1) and (2). The power loss P _OFF of the drive circuit when the solenoid current is cut off can be approximated by the solenoid current i ₀ and the inductance L of the solenoid 6 immediately before the cutoff (that is, both the first and second transistors 4 and 5 are turned off). There is a relationship of the following formula.

Therefore, in the drive circuit shown in FIG. 2, the Zener diode 7 and the drive circuit shown in FIG.

[Problems to be Solved by the Invention]

However, in the above-described conventional driving method, when the overexciting current is flowing, the first and second transistors 4 and 5 are turned on.
In the FF state, the solenoid current i ₀ immediately before becomes large, and there is a problem that the power loss borne by the Zener diode 7 or the third transistor 11 becomes very large as shown by the equation (3). .

In view of the above-mentioned problems, an object of the present invention is to provide a DC solenoid driving method capable of reducing power loss at the time of current interruption during an overexcitation command.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a method for driving a DC solenoid drive device having an overexcitation mode and a holding excitation mode, wherein the overexcitation mode time is reduced by shortening the energization time of the solenoid during the overexcitation mode period. When it becomes smaller, the over-excitation mode is switched to the holding excitation mode before the turning-off of the energization in accordance with the shortening of the energization time, and the energization of the solenoid is cut off at the holding current value.

[Work]

In the present invention, even when the over-excitation mode is in operation, the energization cutoff surface is switched from the excitation mode to the excitation mode to cut off the energization to the solenoid. Power loss during circuit interruption is greatly reduced.

〔Example〕

An embodiment of the method of the present invention will be described below with reference to FIG. 1, since this drive circuit is the same as the conventional example.

That is, the duty value to be output becomes smaller, and commands 1, 2
When both times T ₁ and T ₂ become smaller than T _EX during the above-mentioned over-excitation, T ₂ <T ₁ is set, command 2 is turned off before the current is cut off, the holding current mode is set, and the solenoid current is reduced. . Time T ₁ for this reduction of solenoid current before interruption
-T ₂ is set by the inductance L of the solenoid 6, the circuit resistance value, and the allowable value of the element that causes a loss at the time of interruption.

〔The invention's effect〕

As described above, according to the present invention, when the over-excitation mode time becomes short due to the shortening of the energization time to the solenoid during the over-excitation mode period, the over-excitation is performed before the interruption of the current in accordance with the shortening of the energization time. Since the mode is switched to the holding excitation mode and the energization of the solenoid is cut off by the holding current value, the power loss at the time of breaking the solenoid drive circuit can be reduced. Therefore, the loss of the drive circuit parts can be reduced, the cost and size of the drive device can be reduced, and at the same time,
The above-mentioned problems can be solved by a unique effect that the reliability of parts can be improved.

[Brief description of drawings]

FIG. 1 is a timing chart of a drive circuit according to one embodiment of the method of the present invention, FIGS. 2 to 4 are conventional examples, FIG. 2 is a drive circuit diagram, and FIG. 3 is a constant current chopper control. FIG. 4 is a drive circuit diagram having a function, and FIG. 4 is a timing chart of the drive circuit. 1 ... Duty command means, 4 ... First transistor,
5 ... second transistor, 6 ... solenoid, 7 ... Zener diode, 9 ... DC power supply, 11 ... third transistor, 12 ... diode, 13 ... AND element, 14 ... monostable flip-flop, 16 …… Reference voltage generator, 17 ……
Current detection resistor. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A driving method of a DC solenoid drive device having an over-excitation mode and a holding-excitation mode, wherein the energization time is reduced when the over-excitation mode is reduced by shortening the energization time to the solenoid during the over-excitation mode period. A method for driving a direct current solenoid characterized in that the over-excitation mode is switched to the hold-excitation mode in accordance with the shortening of the energization and the energization to the solenoid is cut off by the holding current value.