JPS58214081A - Solenoid valve driving device - Google Patents

Abstract

PURPOSE:To restrain a recoiling phenomenon of a plunger by reducing attracting voltage to restrain acceleration of the plunger after applying a predetermined attracting voltage to a coil and applying again the attracting voltage just before the plunger collides with a stopper. CONSTITUTION:When signals are applied to an input terminal 11, transistors 21, 22 become conductive so that drive current I flows in a coil 1 and a plunger 3 is attracted and accelerated to the fixed magnetic pole 2 side. When the plunger 3 is displaced to a certain degree, the transistors 21, 22 are shut off to shut off the drive current I in the coil 1. Thus, the displacement speed of the plunger 3 is abruptly restrained by the braking force of a spring 7. When the plunger 3 advances just before it collides with a stopper 10, the transistors 21, 22 become again conductive to prevent recoiling of the plunger 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid valve drive device suitable for controlling the open period of a solenoid valve to control the flow rate of passing fluid.

Generally, solenoid valves are often used as fully open or fully closed on-off valves, but since the flow rate passing through is approximately proportional to the open period of the solenoid valve, for example, as in a fuel injection valve of an internal combustion engine, It can be applied to a flow control valve or the like for intermittently injecting a desired amount of fuel. FIG. 1 shows a sectional view of the fuel injection valve.

As shown in Fig. 1, a fuel injection valve consisting of a solenoid valve is
A coil 1 formed in an annular shape, a cylindrical fixed magnetic pole 2 fixedly disposed within the coil 1, and a plunger (movable magnetic pole piece) 3 freely movably disposed opposite to the lower end surface of the fixed magnetic pole 2.
, a valve body 5 integrally formed with the plunger 3, a valve seat 6 having flow paths 6a and 6b formed so as to be openable and closable by the valve body 5, and a valve seat 6 held by the fixed magnetic pole 2 and connected to the valve body 5 through the plunger 3. and a spring 7 that presses the valve against the valve seat 6 with a predetermined pressure. In addition, the flow paths 5g and 6b
The fuel reservoir 8 is communicated with an intake pipe of an internal combustion engine (not shown), and an orifice 9 is formed in the flow path 6b. Further, the upper limit of the movement of the plunger 3 is limited by the stopper 10 and a protrusion 3a formed on the plunger 3.

The fuel injection valve configured in this manner is operated by turning on and off the drive voltage applied to the coil 1 from the electromagnetic valve drive circuit, and the amount of fuel injection is approximately proportional to the opening period of the valve. Therefore, the injection amount is controlled by applying a driving voltage with a pulse width determined according to the desired flow rate.

Generally, when a solenoid valve is used as a flow rate control valve, in order to improve the precision of flow rate control, it is required that the time (TP) required to fully open the valve be as short as possible. Therefore, until the valve reaches the fully open position, the suction speed is increased by applying a high voltage (suction voltage) to the coil 1 for a time T! The current practice is to shorten the voltage and reduce the holding voltage to the level required to maintain the open state after it is fully opened.

However, if the suction voltage is increased to increase the pulling speed of the granger 3, the repulsive force when the protrusion 3a of the granger 3 collides with the stopper 10 is increased, and the plunger 3 may be repelled. As a result, the movement of the granger 3, that is, the movement of the valve body 5, becomes vibratory.
The disadvantage is that the flow rate control characteristics are unstable and nonlinear. This will be explained in more detail using FIG. 2.

In FIGS. 2(a) and 2(b), the horizontal axis represents time t, the vertical axis represents the drive flow in which the diameter (a) flows through the coil 1, and Φ) represents the displacement of the plunger 3. The horizontal axis of FIG. 2(C) represents the drive pulse width (TP) of the drive pulse signal, and the vertical axis represents the fuel injection amount F.

Now, when a drive pulse signal having a pulse width (TP) determined according to the desired fuel injection amount is input to the solenoid valve drive device, the initial T time is synchronized with the pulse width (Tp). High voltage (suction voltage), residual (TP T
During L) time, a drive voltage that becomes a low voltage (holding voltage) is output. When such a driving voltage is applied to the coil 1, a driving current I having the following waveform flows through the coil 1 as shown in FIG. 2(a). When such a driving current flows through the coil 1, a magnetic flux is generated in the magnetic path consisting of the fixed magnetic pole 2 → plunger 3 → yoke 4, and the magnetic attraction force acting between the granger 3 and the fixed magnetic pole 20 is caused by the force of the spring 7. At a time t, which becomes larger, the granger 3 begins to move, as shown in FIG. 2(b). At the same time, the valve body 5 integrally formed with the granger 3 is separated from the valve seat 6, and the fuel in the fuel reservoir 8 flows out through the orifice 9 into the intake pipe of the internal combustion engine. on the other hand,
The granger 3 is applied with a suction voltage (to
'tc), it is rapidly accelerated and pulled up, and collides with the stopper 10 at time t. Due to the repulsive force caused by this collision, the granger 3 is pulled down to a position where the magnetic attractive force and the repulsive force are balanced, and then pulled up again by the attractive force and collides with the stopper 10 again at time t. Therefore, Granger 3 is shown in Figure 2 (
As shown in b), the fully open position is reached while vibratingly displacing as follows.

Note that the voltage of the coil 1 is switched to a holding voltage at time tL, and is switched to a holding current necessary to hold the plunger 3 in the fully open position.

In this way, when the time corresponding to the drive pulse width (Tp) corresponding to the desired fuel injection amount has elapsed, time 1. The holding voltage is cut off at . As a result, the plunger 3 is pulled down according to the balance between the attractive force due to the residual magnetism and the pulling force due to the spring 7, and the valve is closed at time t4.

However, due to the Granger vibration IIJJ phenomenon described above, the fuel injection amount F and the drive pulse width Tp do not have a linear proportional relationship, and as shown in FIG. This results in an unstable relationship.

Such nonlinearity occurs when the fuel injection valve of an internal combustion engine opens and closes in an extremely short opening period (for example, less than milliseconds), and when trying to control the error in injection amount to less than a few percent. had the disadvantage of being a major hindrance.

Furthermore, the rebound phenomenon of the granger becomes larger as the suction voltage is increased in an attempt to shorten the time required to fully open the valve (between 11 and 12 in Figure 2 (b)) and increase the accuracy of flow rate control. On the contrary, it has the disadvantage that control accuracy is reduced.

An object of the present invention is to provide an electromagnetic valve driving device that can suppress the rebound phenomenon of a plunger that occurs during the opening operation of the electromagnetic valve and improve the nonlinearity of the flow rate characteristics with respect to the opening period.

The present invention suppresses the acceleration of the plunger after applying a predetermined attraction voltage to the coil, that is, by reducing the attraction voltage, and by applying the attraction voltage again just before the granger collides with the stopper. This is intended to suppress the rebound phenomenon of the Granger and improve the flow characteristics.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 3 shows a circuit configuration diagram of an embodiment of the present invention.

As shown in FIG. 3, the drive signal input terminal 11 is connected via a resistor to the base of a transistor 120 whose emitter is grounded, and the collector of this transistor 12 is connected to the input terminal of a monostable multivibrator 13, 14. ing. Further, a control voltage V LC is applied to the collector of this transistor 12 via a resistor. The output end of the simple multivibrator 13 is connected to NAND circuits 16 and 17.
The output terminal of the monostable multivibrator 14 is connected to the input terminal of the NAND circuit 1 via the monostable multivibrator 15.
6 and directly connected to the input terminal of the NAND circuit 170. The output end of the NANDl path 16 is connected to the base of a transistor 20 whose emitter is grounded, and the collector of this transistor 20 is connected to the base of a transistor 21 via a resistor. This transistor 21
The base of is connected to the emitter and the power supply Vm via a resistor. On the other hand, the input end of the NAND circuit 18 is connected to the drive signal input end 11 and the output end of the NAND circuit 17, respectively, and the output end of the NAND circuit 18 is connected to the input end of the NAND circuit 19. There is. The output terminal of this NAND circuit 19 is connected to the base of a transistor 22 whose emitter is grounded, and the collector of the transistor 22 is connected to the collector of the transistor 21 via the coil 1 of the electromagnetic valve.
A power supply Vm is connected via the power supply Vm.

The operation of the embodiment configured as described above is explained in FIG.
This will be explained with reference to a) to (e).

When the drive pulse signal shown in FIG. 4(a) is input to the drive pulse signal input terminal 11, the monostable multivibrators 13, 14.15 and the NAND circuit 16.1? ,1
8.19 is activated, first causing both transistors 21 and 22 to conduct. As a result, the power supply voltage v1 is directly applied to the coil 1, the drive current I shown in FIG. 4(C) is caused to flow, and the plunger 3 is attracted and accelerated toward the fixed magnetic pole 2 side. When the plunger 3 is displaced to a certain extent and reaches an appropriate speed, that is, when the monostable multi-noise (ibrator 13
When the period tx,l determined by has elapsed, the transistors 21.22 are cut off and the drive current I of the coil 1 is cut off. As a result, time tL1 in FIG. 4(d)
~tL! As shown in the figure, the displacement speed of the plunger 3 is rapidly suppressed by the braking force of the subli/gua. When the plunger 3 reaches a point just before colliding with the angle <10, that is, when the time tL determined by the monostable multivibrator 14 has passed, the transistor 2
．． 22 is made conductive again. As a result, the power supply voltage Vm is again applied to the coil 1, and the drive current I is caused to flow therethrough.

As a result, a magnetic attraction force is applied to the plunger 3 that exceeds the repulsion force generated when the plunger 3 collides with the plunger 10, preventing the plunger 3 from bouncing back, and at the time t shown in FIG. 4(d).
As shown between L and tL, the displacement of the granger 3 becomes smooth. Next, at time t when the displacement of the plunger 3 becomes sufficiently stable, the monostable multivibrator 15 is activated, the transistor 21 is cut off, and a holding current reduced by the resistor 23 is caused to flow through the coil 1.

As described above, since the rebound phenomenon of the plunger 3 is suppressed, the relationship between the drive pulse width TP of the drive pulse signal and the actual fuel injection i:F is as shown in FIG. 4 (6). 11 or more, stable linear characteristics are obtained, and highly accurate injection amount control can be performed.

Therefore, according to this embodiment, since the rebound phenomenon of the plunger can be suppressed, the flow rate characteristics with respect to the open period can be made stable and linear even in the case of a short drive pulse width, that is, a short open period. This has the effect that the fuel injection amount can be controlled with high precision, especially when the drive pulse width is 1 millisecond or less, such as in an internal combustion engine.

Furthermore, according to this embodiment, the maximum value of the drive current is significantly reduced compared to the conventional example, so that the total current capacity of each circuit element applied to the drive device can be increased. This allows the device to be made smaller and more economical.

In the above embodiment, the applied voltage was once applied and then the applied voltage was cut off in order to suppress the acceleration of the plunger. Other embodiments of the present invention shown in FIG. 5 may also reduce the voltage.

In FIG. 5, parts with the same reference numerals as those in the embodiment shown in FIG. 3 have the same parts and functions. Also, the difference from the embodiment shown in FIG. 3 is that the NAND1 path 17,
The logic circuit consisting of 18 and 19 is saved, and transistor 2
The base of 2 is connected to the direct drive pulse signal input terminal 1 via a resistor.
There is a + at the point connected to 1.

The operation of the embodiment configured as described above is explained in FIG.
This will be explained with reference to a) to (6).

FIGS. 6(a) to (e) correspond to FIGS. 4(a) to (e), respectively, and the driving pulse signal and driving voltage v
1 drive current ■, plunger displacement mD, and fuel injection amount F are shown.

The basic operation of this embodiment is the same as that of the embodiment shown in FIG.
In the above embodiment, the drive flow I is cut off to greatly suppress acceleration from the time tL determined by the monostable multivibrator 13 to the time t determined by the monostable multivibrator 14. However, this embodiment differs in that the driving voltage during that period is reduced to a level equivalent to the holding voltage. As a result, the braking force of the spring 7 and the magnetic attraction force acting on the granger 3 become approximately the same, and as shown between tL and tLt in FIG. 6(C), the granger 3 moves at a constant speed. It is displaced at .

Therefore, since the speed at the time of collision is not sufficiently reduced, even if the source voltage v1 is applied at tL as in the previous embodiment, tL between tL and t in FIG. As seen in the vicinity of , a slight rebound of the granger 3 remains, but the disturbance in the fuel injection amount can be suppressed to a practically acceptable level as shown in FIG. 6(e).

As described above, according to this embodiment, the same effects as those of the previous embodiment can be obtained, and the circuit configuration can be simplified.

Note that, in practice, the waveform of the drive current I may vary somewhat at the time of switching the drive voltage, as shown in FIG. 7, but there is no problem.

Further, in the above embodiment, the driving voltage between tL and 3 is set to a constant low voltage, but it is also possible to use a high-speed pulse voltage that does not cause the plunger 3 to respond.

As explained above, according to the present invention, the rebound phenomenon of the plunger is suppressed, and the flow rate Jtt during the valve opening period is reduced.
It has the effect of being able to improve the non-linearity of Moreover, 11L for the drive pulse width
This has a significant effect in applications where it is required to suppress variations in the opening time of magnetic valves to within a few percent.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a structural example of a solenoid valve to which the present invention is applied, FIGS. 2(a) to (C) are operation explanatory diagrams of a conventional example, and FIG.
The figure is a circuit configuration diagram of an embodiment of the present invention, and FIGS.
e) is an explanatory diagram of the operation of the illustrated embodiment in FIG. 3, FIG. 5 is a circuit configuration diagram of another embodiment of the present invention, and FIGS. 7 are diagrams for explanation. 1... Coil, 3... Plunger, 10... Stopper, 13.14.15... Monostable multivibrator, 16.17, 18.19... NAND circuit, 20
゜243 4th day

Claims (1)

[Claims] 1. In a solenoid valve drive device that applies voltage to the coil of a solenoid valve to drive the valve via a plunger, after applying a predetermined voltage to the coil, the voltage is immediately reduced to suppress acceleration of the plunger. . A solenoid valve drive device, characterized in that it is configured to apply voltage to the coil again just before the plunger collides with the stopper.