JP2631070B2 - Phase control device for electromagnetic pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the phase of fuel pressure and oil quantity of an electromagnetic pump.

[0002]

2. Description of the Related Art An electromagnetic pump used in a combustion apparatus supplies fuel compressed to a nozzle by reciprocating movement of an electromagnetic plunger, but the discharge pressure pulsates due to its operation principle. Since the pulsating pressure affects the combustion state, it is desired to reduce the pulsating pressure. Conventionally, for example, an accumulator has been incorporated in an electromagnetic pump.

[0003]

However, the effect of the accumulator for reducing the pulsating pressure is limited due to various restrictions. Therefore, as another measure for reducing the pulsating pressure, the driving frequency of the electromagnetic pump is changed to the commercial frequency. Is 5
It has been considered that the pulsation pressure is reduced by increasing the stroke of the electromagnetic plunger to a value higher than 0HZ or 60HZ.

As a circuit method for increasing the driving frequency,
A method of rectifying and smoothing an AC voltage to form a DC voltage, converting the DC voltage into a rectangular pulse voltage to drive the electromagnetic pump at an arbitrary frequency, and a method of performing full-wave rectification and phase control of an AC power supply. However, in the former case, the external dimensions of the rectifying capacitor in the power supply portion become large, and it is necessary to separately add a transmission circuit portion, so that the circuit board becomes large and the cost increases.

In the latter method, the number of parts is generally small, which is advantageous in terms of cost. However, when the phase control is performed after full-wave rectification of an electromagnetic pump having a solenoid coil (inductance), The commutation failure of the thyristor is caused by the back electromotive voltage generated when the voltage is cut off, and the phase control becomes practically impossible. This situation will be described with reference to FIG. 8. The commercial AC voltage waveform shown in FIG.
When full-wave rectification is performed as shown in (b) and a resistive load is phase-controlled by a thyristor, a voltage waveform as shown in FIG. 8C is obtained. However, a phase control is performed on a load (electromagnetic pump) including an inductance. In this case, commutation failure occurs at the end of each half cycle, and phase control cannot be performed at all, as shown in FIG.

The problem of the full-wave rectification phase control can be solved by removing the back electromotive force by bypassing with a diode.
It can be controlled like the resistance load shown in FIG.
When the back electromotive force is removed, the electromagnetic pump cannot obtain a predetermined discharge pressure, and the ability to suck oil tends to be extremely reduced.

Therefore, in the present invention, the above-mentioned uncontrollable state of the full-wave rectification phase control is eliminated, and a predetermined performance of the electromagnetic pump is ensured by applying a back electromotive force to the electromagnetic pump. It is an object to provide a phase control device for an electromagnetic pump as described above.

[0008]

SUMMARY OF THE INVENTION The gist of the present invention resides in that at least a solenoid coil, a thyristor, and a switching element of an electromagnetic pump are connected in series to a rectifier for full-wave rectification of an AC voltage. A voltage converting means for converting the voltage waveform obtained by the rectifying means into a symmetrical waveform around a center while leaving a predetermined phase angle at both ends every half cycle; and closing the switching element; Turn-on forming means for outputting a signal for firing the thyristor at the time of rising of the waveform obtained by the waveform converting means; and a period longer than the turn-off time of the thyristor at the time of falling of the waveform obtained by the waveform converting means. A turn-off forming means for opening the switching element; and a pulse width adjusting means for adjusting a pulse width of a waveform obtained by the waveform converting means.

Here, the waveform converting means includes a reducing means for reducing the voltage waveform obtained by the rectifying means with a desired gain, a reference voltage forming means for forming a reference voltage, and a voltage waveform reduced by the reducing means. Means for setting the output to HI when is larger than the reference voltage,
In this case, the pal width adjusting means may be a variable resistor for changing the reference voltage.

Further, the turn-on forming means has a differentiating circuit for outputting a pulse to the gate of the thyristor at the time of rising of the waveform obtained by the waveform converting means, and the turn-off forming means converts the waveform obtained by the waveform converting means. It may be configured to include an inverter to be inverted, a differentiating circuit that outputs a pulse at the time when the output waveform of the inverter rises, and a unit that opens and closes the switching element for the pulse time output from the differentiating circuit.

[0011]

Therefore, the AC voltage is full-wave rectified by the rectifying means to have a waveform as shown in FIG. 4 (a). Based on the DC voltage rectified by the full-wave, the waveform converting means forms a boundary at the center of each half cycle. For example, FIG.
The waveform of (c) is formed. Then, when a signal necessary for firing the thyristor is output at the time of the rise of the waveform obtained by the waveform conversion means by the turn-on forming means, the thyristor turns on and current starts to flow through the solenoid coil of the electromagnetic pump. , By turn-off forming means,
When the switching element is opened at the time when the waveform obtained by the waveform conversion means falls, the thyristor turns off. Moreover,
Since the waveform obtained by the waveform conversion means has a symmetrical shape with a predetermined phase angle at both ends and a center as a boundary, a half-cycle waveform that is full-wave rectified has a voltage change from 0 to 180 degrees. Thus, when the same voltage is reached, the thyristor turns on and off. Further, since the thyristor is turned off at a phase angle smaller than 180 degrees in each half cycle, it is possible to secure a time during which the back electromotive voltage generated by the solenoid coil can be generated with the turn-off.
The voltage applied to both ends of the solenoid coil is shown in FIG.
It becomes as shown in.

When the pulse width of the waveform obtained by the waveform converting means is adjusted by the pulse width adjusting means, the conduction angle of the thyristor is changed, and the current supply time to the solenoid coil can be changed to a desired time. Thus, the phase control of the fuel injection pump becomes possible.

The waveform converting means includes a reducing means for reducing the output of the rectifying means with a desired gain, a reference voltage forming means for forming a reference voltage, and a voltage waveform reduced by the reducing means, which is smaller than the reference voltage. HI output when large
Means, the output of the rectifying means can be converted into a rectangular wave that is symmetrical about the center every half cycle, and the pulse width adjusting means is composed of a variable resistor for changing the reference voltage. Then, by adjusting the resistance value of the variable resistor, the area of the voltage waveform reduced by the reduction means, which is larger than the reference voltage, can be changed, and the pulse width of the rectangular wave can be changed, and the phase angle of the turn-on and turn-off can be changed. Can be changed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, the electromagnetic pump 1 comprises:
An electromagnetic plunger 3 that reciprocates due to the intermittent electromagnetic force of the solenoid coil 2 is held in an electromagnetic plunger working chamber 6 by an upper holding spring 4 and a lower holding spring 5.

Below the electromagnetic plunger 3, a piston 7 is integrally connected to the electromagnetic plunger 3 and is fitted into a cylinder 8. The reciprocating motion of the piston 8 changes the volume of the pump chamber 9, and the suction valve In cooperation with 10 and the discharge valve 11, a pump action is performed. That is, the suction valve 1
The fuel sucked into the pump chamber 9 through the discharge valve 11
Through the hole 13 formed in the electromagnetic plunger 3 and the hole 15 formed in the fixed magnetic rod 14 to the electromagnetic valve 16, which is sucked and opened by the solenoid coil 2. Discharge is performed through a discharge hole 18 formed in a discharge joint 17 via the electromagnetic valve 16. The discharge pressure is set at the nozzle 19, the nozzle 1
9 is adjusted by a pressure adjusting device 22 including a return valve 20 for closing the return valve 9 and a spring 21 for pressing the return valve 20 toward the nozzle.

When the solenoid coil 2 is energized, the electromagnetic plunger 3 and the piston 7 move upward,
As the volume of the pump chamber 9 increases, the suction valve 1
When the fuel is supplied through the solenoid coil 2 and the power supply to the solenoid coil 2 is stopped, the electromagnetic plunger 3 and the piston 7 are pushed back downward by the spring force of the upper holding spring 4, and the fuel in the pump chamber is pressurized. The ink is discharged from the discharge holes 18.

The drive of the electromagnetic pump 1 is controlled by a drive circuit shown in FIG. 3, and the drive circuit will be described below.

The drive circuit is connected to a commercial AC power supply 30 of, for example, 100 V, 50 HZ or 60 HZ. The AC voltage supplied from the commercial AC power supply 30 is first subjected to full-wave rectification through bridge diodes (D 1 to D 4). I do. A diode D5 is provided between the output terminals of the bridge diodes (D1 to D4) (between the node and the reference node).
, Resistors R1 and R2 are connected in series, and a node voltage between these resistors is applied to a ratio inverting input terminal of the voltage follower 31. The output terminal (node) of the voltage follower 31 is connected to the ratio inverting input terminal of the comparator 32, and the inverting input terminal of the comparator 32 is connected to the node via a diode D6 and a resistor R3 connected in series. At the same time, it is connected to a reference node via a capacitor C1 and a variable resistor VR1 connected in parallel. Thus, the comparator 32 sets the node voltage between R3 and VR1 to VR.
And adjustable reference voltage V _O 1, by comparing the output voltage of the reference voltage V _O and the voltage follower 31, if the output voltage of the voltage follower 31 is higher than the reference voltage V _O, output terminals (nodes) A HI signal is output.

The output signal of the comparator 32 is input to a first differentiating circuit 33 and also input to a second differentiating circuit 34 via an inverter 35. These first and second differentiating circuits 34 and 35 include two inverters (36
, 37, 38 and 39), the output side inverters 37 and 39 and the capacitors C2 and C3 are connected.
C3 is connected to the constant voltage power supply (Vcc).
4 and R5 are connected.

The output terminal (node) of the first differentiating circuit 33 is connected to the gate terminal (G) of the thyristor 40 via a resistor R6, and the gate terminal (G) of the thyristor 40 is connected in parallel. It is connected to a reference node via a resistor R7 and a capacitor C4, and applies a voltage between the gate and the cathode when the output of the comparator 32 rises from LOW to HI.

The cathode terminal (K) of the thyristor 40 is
The anode terminal (A) is connected to the node via the solenoid coil 2 of the electromagnetic pump 1, and is connected to the node via a series circuit of the resistor R8 and the diode D7. . The emitter of the transistor TR1 is connected to the reference node, and the base of the transistor TR1 is connected between the resistor R9 and the Zener diode TD (node) connected in series between the output terminals of the bridge diodes (D1 to D4). I have. Thyristor 40
When a voltage is applied to the gate terminal (G), the transistor TR1 is ON at a potential determined by the breakdown voltage of the Zener diode TD at that point, and the thyristor 40 is allowed to turn on.

On the other hand, the output terminal of the second differentiating circuit 34 is connected to the base of the transistor TR2 via the resistor R10, the collector is connected to the node, and the emitter is connected to the reference node. When the output of the transistor TR2 changes from HI to LOW, the collector-emitter of the transistor TR2 conducts, and the base-emitter of the transistor TR1 is short-circuited. Note that the time for which the collector-emitter conduction of the transistor TR2 is conducted is set to be longer than the turn-off time of the thyristor 40.

In the driving circuit having the above configuration, the AC voltage of the commercial AC power supply 30 is applied to the bridge diodes (D1 to D1).
When the full-wave rectification is performed in 4), the waveform shown in FIG. 4A is obtained. The waveform obtained at the output terminal (node) of the voltage follower 31 is reduced to an amplitude determined by the resistors R1 and R2. As shown in FIG.

[0025] Then, the waveform of FIG. 4 (b), is compared with a reference voltage V _O at the comparator 32, the reference voltage V _O
A rectangular wave (FIG. 4 (c)) which becomes HI is obtained in a larger region, that is, a region symmetrically spread on both sides around the maximum value of each half cycle.

When the waveform of FIG. 4C is input to the first differentiating circuit 33, a pulse wave as shown in FIG. 4D, which becomes HI at the rising point, is output.
Since the waveform of FIG. 4C is inverted and input to the differentiating circuit 34, the pulse shown in FIG. 4E which becomes HI when the waveform of FIG. Waves are output.

When the pulse wave output from the first differentiating circuit 33 is input to the gate terminal of the thyristor 40, the transistor TR1 is turned on at this time, so that the thyristor 40 is turned on and the electromagnetic pump 1 is turned on. The current starts to flow through the solenoid coil 2. Thereafter, the pulse wave output from the second differentiating circuit 34 is output to the transistor TR2.
When the voltage is applied to the base of the transistor TR1, the base and the emitter of the transistor TR1 are short-circuited, the transistor TR1 is opened, and the base voltage (voltage of the node) of the transistor TR1 is changed as shown in FIG. The waveform is the inverse of (e). Since the period during which the transistor TR1 is opened is set to be equal to or longer than the turn-off time of the thyristor 40, the anode current of the thyristor 40 becomes equal to or lower than the holding current, and the thyristor 40 is turned off.

Therefore, the thyristor 40 is not
(C) is conducted for the same time as the pulse width of the rectangular wave, and the reference voltage V _{O of the} comparator 32 is applied.
Can be changed by the variable resistor VR1,
The pulse width (T) of the voltage waveform applied to the solenoid coil 2 by changing the pulse width of the output waveform of the comparator 32
Can be changed.

As described above, since the phase of the electromagnetic pump 1 can be controlled by using twice the frequency of the commercial power supply, the stroke of the electromagnetic plunger 3 of the electromagnetic pump 1 is smaller than that when the electromagnetic pump 1 is driven at the commercial power supply frequency. As shown in FIG. 5B, the pulsating pressure of the electromagnetic pump 1 can be reduced to half or less of the conventional pulsating pressure (FIG. 5A).

When the thyristor 40 is turned off, the electromagnetic energy stored in the solenoid coil 2 loses its place to go, and a counter electromotive voltage is generated at both ends of the solenoid coil 2. In particular, when the thyristor 40 is turned off in a state where the voltage between both ends of the solenoid coil is relatively high as in this embodiment, the back electromotive voltage becomes very large, but the resistance R8 provided in parallel with the solenoid coil 2 is increased. And the diode D7, the peak value of the back electromotive voltage is suppressed to substantially the same value as the voltage peak value in the positive direction, and the voltage waveform applied to both ends of the solenoid coil 2 as a whole is as shown in FIG. .

For this reason, the back electromotive voltage generated when the thyristor 40 is turned off causes a current in the reverse direction to flow through the solenoid coil 2 to generate an electromagnetic force for moving the electromagnetic plunger 3 downward, and is pushed up against the upper holding spring. The electromagnetic plunger 3 that has been moved is returned downward at an accelerated rate by the electromagnetic force in addition to the spring force of the upper holding spring 4. Therefore, the electromagnetic plunger 3 can be quickly moved up and down by the electromagnetic force, and the suction / discharge ability of the electromagnetic pump 1 can be improved.

When the commercial power supply of the electromagnetic pump 1 is shared by 100 V and 200 V, the pulse width adjusting means surrounded by a broken line in FIG. 3 is replaced by a variable resistor VR as shown in FIG.
1, a phase control waveform at 100 V determined by VR2 by connecting a variable resistor VR2 in parallel via a switch SW (shown by a solid line in FIG. 7), and
200V determined by VR1 by turning off switch SW
A phase control waveform at the time (indicated by a two-dot chain line in FIG. 7) may be obtained. By introducing such a circuit, there is no need to change the solenoid coil 2 and only 10
Switching between 0V and 200V becomes possible.

[0033]

As described above, according to the present invention,
The solenoid coil, thyristor, and switching element of the electromagnetic pump are connected in series to the rectification means, and the full-wave rectified waveform is symmetrical about the center, leaving a predetermined phase angle at both ends every half cycle. The thyristor is turned on at the time of the rise of the converted waveform, and a current flows through the solenoid coil.After that, at the time of the fall of the converted waveform, a time longer than the turn-off time of the thyristor,
Since the switching element is opened, the thyristor can be turned off without causing commutation failure at the end of each half cycle. Therefore, if the pulse width of the waveform obtained by the waveform conversion means is adjusted by the pulse width adjustment means,
The current supply time to the solenoid coil can be changed to a desired value, and the phase control of the electromagnetic pump can be accurately performed.

Also, since the thyristor is reliably turned off to secure the time for generating the back electromotive voltage, the discharge pressure of the electromagnetic pump and the oil suction capacity are increased, and the predetermined performance of the electromagnetic pump is ensured. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an electromagnetic pump used in the present invention.

FIG. 2 is a cross-sectional view showing an electromagnetic pump used in the present invention.

FIG. 3 is a circuit diagram showing a phase control device for an electromagnetic pump according to the present invention.

4 (a) shows the voltage of the node in the circuit diagram of FIG. 3, FIG. 4 (b) shows the voltage of the node in the circuit diagram of FIG. 3, and FIG. 4 (c) shows the circuit of FIG. 4D shows the voltage of the node in the circuit diagram of FIG. 3, FIG. 4E shows the voltage of the node in the circuit diagram of FIG. 3, and FIG. FIG. 4 (g) is a waveform diagram showing the voltage at the nodes of the circuit diagram of FIG. 3 and the voltage across the solenoid coil.

FIG. 5A shows a conventional driving frequency (50 / 60H);
Z) shows the pulsating pressure when the electromagnetic pump is driven, and FIG. 5B is an experimental characteristic diagram showing the pulsating pressure when the electromagnetic pump is driven by the phase control device of the present invention.

FIG. 6 is a circuit diagram showing another example of a circuit surrounded by a broken line in FIG. 3;

FIG. 7 is a waveform diagram showing the voltage across the solenoid coil when the commercial power supply is switched between 100V and 200V using the circuit shown in FIG.

FIG. 8 is a waveform diagram illustrating full-wave rectification phase control of a conventional electromagnetic pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic pump 2 Solenoid coil 30 Commercial AC power supply 31 Voltage follower 32 Comparator 33 First differentiating circuit 34 Second differentiating circuit 35-39 Inverter 40 Thyristor D1-D4 Bridge diode TR1, TR2 Transistor VR1, VR2 Variable resistance

Claims (4)

(57) [Claims] At least a solenoid coil, a thyristor, and a switching element of an electromagnetic pump are connected in series to a rectifying means for full-wave rectifying an AC voltage, and a voltage waveform obtained by the rectifying means is changed every half cycle. Waveform converting means for converting a waveform symmetrical about the center while leaving a predetermined phase angle at both ends; closing the switching element, and turning on the thyristor at a rising point of the waveform obtained by the waveform converting means. Turn-on forming means for outputting a signal to be turned on, turn-off forming means for opening the switching element for a period longer than the turn-off time of the thyristor at the time of falling of the waveform obtained by the waveform converting means, and the waveform converting means And a pulse width adjusting means for adjusting the pulse width of the waveform obtained in step (a). 2. The waveform converting means includes a reducing means for reducing a voltage waveform obtained by the rectifying means with a desired gain, a reference voltage forming means for forming a reference voltage, and a voltage waveform reduced by the reducing means. 2. A phase control device for an electromagnetic pump according to claim 1, further comprising: means for setting an output to HI when is larger than the reference voltage. 3. The electromagnetic pump phase control device according to claim 2, wherein the pulse width adjusting means is a variable resistor for changing a reference voltage. 4. The turn-on forming means includes a differentiating circuit for outputting a pulse to the gate of the thyristor at the time of rising of the waveform obtained by the waveform converting means, and the turn-off forming means converts the waveform obtained by the waveform converting means. 2. The electromagnetic pump according to claim 1, further comprising an inverter to be inverted, a differentiating circuit for outputting a pulse when the output waveform of the inverter rises, and means for opening the switching element for the pulse time output from the differentiating circuit. Phase control device.