JPH0319429B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid valve drive circuit, and more particularly, to a solenoid valve drive circuit that can drive a solenoid valve at high speed.

Generally, in order to speed up the operation of a solenoid valve,
Requires a drive current with a steep rise. Therefore,
Conventionally, a solenoid valve drive circuit has been proposed that maintains the holding current at the holding current that flows through the solenoid coil of the solenoid valve immediately before operation, regardless of voltage fluctuations such as the power supply voltage, and enables high-speed drive of the solenoid valve. (Japanese Unexamined Patent Publication No. 109864/1983).

However, in order to keep the holding current constant, this proposed device requires a detection resistor for detecting the magnitude of the holding current, a feedback circuit for feeding back the detection result by the detection resistor, etc. Requires complex circuitry. Furthermore,
The optimal holding current changes depending on the temperature conditions of the solenoid valve, etc., but since the conventional device described above keeps the holding current constant, it is necessary to set a margin that takes into account fluctuations in the optimal holding current. However, there is also the problem that it is not possible to always ensure the best operating conditions.

Therefore, an object of the present invention is to provide an inexpensive and high-performance electromagnetic valve drive circuit that can further improve the operating speed without using complicated electronic circuits.

The present invention provides a driving circuit for a solenoid valve configured to perform opening and closing operations by a valve body positioned in accordance with an excitation current applied to an electromagnetic coil, in which the solenoid valve is opened and closed by the valve body. an on/off switch means connected to the valve body so that the operating state is changed from a desired valve body position immediately before switching is initiated; The present invention is characterized in that it includes energization control means for applying an excitation current to the electromagnetic coil for moving the valve body toward the required valve body position only until the valve body exceeds the required valve body position.

The on/off switch means is a first on/off switch that operates when the valve body reaches a position immediately before starting to open the solenoid valve, and a first on/off switch that operates when the valve body reaches a position immediately before starting to close the solenoid valve. It consists of two types of switches: a second on/off switch that operates when On the other hand, when switching the solenoid valve from the open state to the closed state, the excitation current is controlled by the second on/off switch, and the valve body is moved to the position immediately before the valve starts closing. It may be configured to repeatedly move up to . Alternatively, only the first or second on/off switch may be provided and used as the on/off switch means, and the above-mentioned excitation current energization control may be performed only when the valve is opened or closed.

By repeatedly placing the solenoid valve in the open state or the state immediately before the start of the closed state by the above-mentioned energization control in response to the on/off switch means, the valve body of the solenoid valve is kept in a slight vibration state during the standby period, thereby causing the valve body to vibrate slightly. It is possible to significantly reduce the static frictional force acting on the surface. Therefore, when an excitation current is continuously supplied to the electromagnetic coil by a separately provided means, the valve body moves in a desired direction with extremely good response, making it possible to realize high-speed drive of the electromagnetic valve. can.

Hereinafter, the present invention will be explained in more detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of a solenoid valve drive circuit according to the present invention. A solenoid valve drive circuit 1 according to the present invention is a circuit for driving a spool valve 3 by an electromagnetic coil 2, thereby driving a solenoid valve 4 configured to open and close the valve at high speed. . This electromagnetic valve drive circuit 1 includes a switch device 5 that is turned on and off depending on the position of the spool valve 3;
It has a current control circuit 6 for controlling the excitation current supplied to the electromagnetic coil 2 in response to the on/off operation of the switch device 5.

The switch device 5 has fixed contacts 9 and 10 provided at intervals on a support rod 8 made of an insulating material that is fixed to the main body 7 of the solenoid valve 4, and a switch device 5 that is connected to Both fixed contacts 9, 10
A movable contact 12 is fixed to the end of the spring receiver 11 so as to move between the two. A disk-shaped spring receiver 11 is fixed to the spool valve 3 by a rod 13, and an elastic coil spring 14 is interposed between the spring receiver 11 and the side surface of the main body 7 facing the spring receiver 11. equipped with spool valve 3
is always biased by a spring in the direction of arrow A.

When the electromagnetic coil 2 is in the de-energized state, the spool valve 3 is in the position shown and the electromagnetic valve 4 is in the open state. At this time, the fixed contact 9 and the movable contact 12 constituting the first switch SW ₁ are in contact with each other, and immediately before the spool valve 3 starts closing the input port 15,
In other words, the contact between the fixed contact 9 and the movable contact 12 is released at a predetermined valve body position immediately before the solenoid valve 4 starts to close, and the fixed contact 9 and the movable contact are released so that the first switch SW ₁ is turned off. A contact point 12 is formed. On the other hand, when the electromagnetic coil 2 is energized and the spring receiver 11 made of a magnetic material is pulled back fully in the direction of arrow B against the spring force of the resilient coil spring 14, the input port 15 is completely blocked by the spool valve 3. As a result, the solenoid valve 4 is closed. At this time, the fixed contact 10 and the movable contact 12 constituting the second switch _SW2 are in contact with each other, and the first switch _SW1 is off. The second switch SW ₂ is configured to be turned off when the spool valve 3 moves in the direction of arrow A and the electromagnetic valve 4 crosses another predetermined valve position immediately before it becomes open. ing. In this way, the first switch SW ₁ is switched from on to off by passing the predetermined valve body position just before the solenoid valve 4 starts to be switched from the open state to the closed state, while the second switch SW 1 The switch SW ₂ is switched from on to off by passing another predetermined valve body position just before the solenoid valve 4 begins to be switched from the closed state to the open state. That is, the operating states of the first and second switches SW ₁ and SW ₂ are changed with respect to each predetermined valve body position as a boundary.

In order to extract a signal indicating the on/off state of each switch SW ₁ and SW ₂ , each fixed contact 9, 10 is
The movable contact 12 is connected to the power supply +V via resistors 16 and 17, respectively, and the movable contact 12 is connected to the spring receiver 11 and the rod 1.
3. Grounded via the spool valve 3 and main body 7. Therefore, each switch SW ₁ and SW ₂ is turned on,
In response to turning off, the potential of each output line 18, 19 changes.

The current control circuit 6 has an output line 19 connected to the inverter 2.
0, and a NAND gate 22, to which the output line 18 is directly connected to one input, and the other input of the NAND gate 21 is connected to a start switch ST.
A power supply voltage +V is applied through the NAND gate 22 , and the other input of the NAND gate 22 is connected to the other input of the NAND gate 21 through the inverter 23 . Each output of the NAND gates 21 and 22 is applied to the other input of an AND gate 24 to which a control pulse CP is applied, and the output of the AND gate 24 is connected via a resistor 25 to a switch whose emitter is grounded. is applied to the base of the switching transistor 26. switching transistor 26
An electromagnetic coil 2 is inserted into the collector circuit, and a protection diode 27 of a transistor 26 is connected in parallel to this electromagnetic coil 2.

Next, the operation of the drive circuit 1 shown in FIG. 1 will be explained with reference to FIG. 2. When a power switch (not shown) is turned on at time t= _t1 , the power supply voltage is applied, but the level of the control pulse CP is "0".
Therefore, transistor 26 is off and electromagnetic coil 2 remains deenergized. Therefore, in this case, the solenoid valve 4 is in an open state. When the level of the control pulse CP becomes "1" at t=t ₂ ,
In this case, the start switch ST is off and
In addition, since the switch SW ₁ is on and the switch SW ₂ is off, the outputs of the NAND gates 21 and 22 are both "1", so the transistor 26 is turned on and the electromagnetic coil 2 is energized. As a result, the spool valve 3 moves in the direction of arrow B, but at t= _t3 , when the solenoid valve 4 is about to start closing, the first switch SW ₁ opens, so the level of the output line 18 becomes "1". Therefore, the output level _L1 of the NAND gate 22 becomes "0". Therefore, and gate 2
4's output level _L3 also becomes the "0" level.
Therefore, the exciting current I flowing through the electromagnetic coil 2 is
It begins to flow at t ₂ but is cut off at t ₃ (Fig. 2 c, e).

FIG. 2g shows how the position of the spool valve 3 shown in FIG. 1 changes with time t taken on the horizontal axis. In Figure 2g, the vertical axis is the position P of the spool valve 3.
, and the position shown in Figure 1 is P=0
The first switch SW 1 is switched from ON to OFF at P=P ₁ , and the second switch SW ₁ is switched from ON to OFF.
SW ₂ is switched from off to on when P=P ₂ ,
When the spool valve 3 is fully moved in the direction of arrow B, P=P _nax . And P≧P ₀₂ is the solenoid valve 4
is the closed region, P≦P ₀₁ is the region where the solenoid valve 4 is open, P ₀₁
<P<P ₀₂ is the region of the opening/closing transient state of the solenoid valve 4.

As can be seen from the above explanation, when the excitation current I starts flowing at t= _t2 , the spool valve 3 starts to move in the direction of arrow B, and even when the excitation current I is cut off at t= _t3 , the spool valve 3 is affected by the inertial force. The robot moves beyond position P ₁ and heads in the direction of arrow A a little after t ₃ . As a result, at time t ₄ , which is a little after t ₃ , the switch SW ₁ is closed again, and therefore the output level L ₂ becomes "1", and the output level
_L3 also becomes "1". As a result, the exciting current I starts flowing again, and the same operation is repeated thereafter. In this way, the excitation current I is intermittently supplied depending on whether the first switch SW ₁ is turned on or off, so that the spool valve 3
In the vicinity of position P ₁ , as shown in Fig. 2g,
It is in a state of slight vibration.

In this state, the start switch ST is closed at t= _t5 , and the start switch ST is closed.
When the level of the potential _VST on the output side of ST becomes "1" (FIG. 2a), the output level _L1 of the NAND gate 22 is held at a high level regardless of the level of the output line 18. Therefore, in this case, the spool valve 3 moves in the direction of arrow B due to the energization of the electromagnetic coil 2, and even if the first switch SW ₁ is turned off, the energization of the electromagnetic coil 2 continues, The spool valve 3 reaches position _P2 , and the solenoid valve 4 becomes open.

When the spool valve 3 reaches the position _P2 as described above, the second switch _SW2 is closed at t= _t6 , and the output level of the inverter 20 becomes "1".
Therefore, the output level _L2 of the NAND gate 21 becomes "0". At this time, the NAND gate 22 is given a "0" level signal by the inverter 23 and a "0" level signal by the switch _SW1 , so its output level _L2 remains held at "1". (Figure 2d). Therefore, t
At =t ₅ , the excitation current flowing through the electromagnetic coil 2 is cut off, and the spool valve 3 is returned in the direction of arrow A by the spring force, but the spool valve 3 is not in the position.
When the switch SW 2 is further moved in the direction of the arrow A by P ₂ , the switch SW ₂ is turned off and the exciting current is supplied to the electromagnetic coil 2 again. This intermittent operation of the excitation current is similar to the operation performed at position _P1 , so that the spool valve 3 is connected to the solenoid valve 4.
is controlled to maintain the state immediately before the open state.

When the switch ST is opened at t= _t7 and the level of the control pulse CP becomes "0", the output level _L3 becomes "0", the electromagnetic coil 2 becomes deenergized, and the electromagnetic valve 4 becomes open. Become.

According to such a configuration, when the solenoid valve 4 is in the open state, the exciting current is intermittently supplied and the spool valve 3 vibrates slightly near the position immediately before starting to close, so that static frictional resistance is eliminated and the start is stopped. When the switch ST is turned on, the spool valve 3 moves at high speed in the direction of arrow B, and the solenoid valve 4 is closed in a very short time. Such high-speed operation is performed in exactly the same way when changing the solenoid valve 4 from the closed state to the open state. The position of the spool valve 3 is the first and second switch SW ₁ ,
Since it is determined by SW ₂ , the position of the spool valve 3 during standby can be set extremely easily and accurately.
The spool valve 3 is always kept at the desired critical position _P1 or
It can be located at P ₂ .

FIG. 3 shows another embodiment of the electromagnetic valve drive circuit according to the invention. In this embodiment, a valve seat 32 formed in a case 31 is used to drive an electromagnetic valve 34 which is configured to close or open when a distal end 33a of a valve body 33 seats on and separates from the valve seat 32. A solenoid valve drive circuit 35 is shown.

The electromagnetic valve drive circuit 35 includes a switch 36 that is turned on and off depending on the position of the valve body 33, and a switch 36 that is turned on and off depending on the position of the valve body 33.
A current control circuit 38 is provided for intermittently supplying excitation current to the 34 electromagnetic coils 37 in response to the on/off operations of the 6 electromagnetic coils 37.

The switch 36 includes a conductive disk-shaped spring support 39 fixed to the rear end of the valve body 33 and a fixed electrode 40 fixed to the conductive case 31. A contraction coil spring 41 is interposed between the spring receiver 39 and the case 31, and urges the valve body 33 away from the valve seat 32. The contraction coil spring 41 is electrically conductive, and the case side end of the contraction coil spring 41 is in contact with a terminal 43 fixed to the case 31 with an insulating layer 42 in between. When the electromagnetic coil 37 is in a de-energized state, the electromagnetic valve 34 is in an open state, and the switch 36 is in an open state.
is in the on state. On the other hand, when the electromagnetic coil 37 is energized, the valve body 33 moves in the direction of arrow C against the spring force of the contraction coil spring 41, the electromagnetic valve 34 is closed, and the switch 36 is closed. It is in the off state. The switch 36 is configured to be turned on/off when the valve body 33 is at a position immediately before the valve closing operation is expected to begin.

In order to extract a signal indicating whether the switch 36 is on or off, the electrode 40 is grounded, and the power supply voltage +V is applied to the terminal 43 via a resistor 44.
Therefore, if switch 36 is on, terminal 4
The potential of the terminal 43 becomes the ground level, and when the switch 36 is turned off, the potential of the terminal 43 becomes the same high level as the power supply voltage +V.

The current limiting circuit 38 includes an inverter 45 to which the potential of a terminal 43 is applied, an AND gate 46 to which the output of the inverter 45 is applied to one input terminal, and an output of the AND gate 46 to one of its input terminals. It has an OR gate 47 which is applied to. The output of the OR gate 47 is applied to the base of a switching transistor 49 whose emitter is grounded, and the collector of the transistor 49 is connected to the power supply voltage +V via an electromagnetic coil 37 to which a diode 50 is connected in parallel. is applied. A first control signal CS1 shown in FIG. 4a is applied to the other input terminal of the AND gate 46, and a second control signal _CS1 shown in FIG. 4b is applied to the other input terminal of the OR gate 47.
CS ₂ is applied.

Next, the operation of the electromagnetic valve drive circuit 35 shown in FIG. 3 will be explained with reference to FIG. 4.

Before time t= _t10 , the levels of the first and second control signals CS ₁ and CS ₂ are "0", so the transistor 49 is turned off regardless of whether the switch 36 is on or off, and the electromagnetic Valve 34 is in an open state as shown in FIG.

When the level of the first control signal _CS1 becomes "1" at time _t10 , the AND gate 46 is opened, and in response to the ON state of the switch 36, the AND gate 46 is opened.
The output voltage V ₁ (see Figure 4c) becomes "1", and
Since the output voltage V ₂ of the OR gate 47 also becomes "1" (see FIG. 4 d), the transistor 49 is turned on and the exciting current I begins to flow through the electromagnetic coil 37 (see FIG. 4 e). As time passes, the excitation current I increases and the valve body 33 moves in the direction of arrow C against the spring force, but when the valve body 33 moves to a predetermined position just before the start of the valve closing operation, the switch is activated. 36 is turned off, the output level of the inverter 45 becomes "0", and the level of the output voltage _V1 becomes "0".
Therefore, the transistor 49 is turned off.

In FIG. 4f, the position P of the valve body 33 is plotted on the vertical axis to indicate its instantaneous position, and this predetermined position is indicated by P _a in FIG. 4f. It is at time _t11 that the valve body 33 reaches P _a for the first time after _t10 , and here the transistor 49
is turned off and the exciting current I is cut off, so the valve body 33 is pulled back by the spring force. As a result, the switch 36 is turned on again, and the exciting current I flows.
This operation is performed by the first switch SW ₁ explained in Fig. 1.
This is similar to the intermittent supply operation of the excitation current by the excitation current I, which causes the excitation current I to flow intermittently, and the valve body 33
moves back and forth near P=P _a , and the solenoid valve 34 is kept open.

When the level of the second control signal CS ₂ becomes "1" at t=t ₁₂ , the output voltage V ₁ of the AND gate 46
The level of the output voltage _V2 becomes "1" regardless of the level of V2, and the transistor 49 is turned on.
As a result, the exciting current I flows continuously through the electromagnetic coil 37, and the tip end 33a of the valve body 33 is connected to the valve seat 37.
The solenoid valve 34 reaches the closed position _Pb .

At t= _t13 after a predetermined period of time has elapsed from time _t12 , the second control signal _S2 changes to a pulse signal with a predetermined cycle so that the solenoid valve 34 does not follow the opening/closing process. Solenoid valve 34 with electric power
It is designed to maintain the closed state. this is,
This takes advantage of the general characteristic of solenoid valves that once the closed state is established, the excitation power required to maintain it is less than that during opening/closing operations. Note that the first control signal CS ₁ has already been returned to the "0" level at t=t ₁₃ (>t ₁₂ ).

When the level of the second control signal _CS2 becomes "0" at time t= _t14 , the transistor 49 is turned off, and the excitation current I decreases according to a predetermined curve.
Along with this, the position of the valve body 33 also returns to its original position at t= _t15 .

According to the above configuration, during the period t ₁₀ <t < t ₁₂ , the valve body 33 vibrates near the critical position P _a as shown in FIG.
Static frictional resistance between the and its guide member disappears,
When a valve closing instruction is given by the second control signal _CS2 , the valve body 33 moves extremely quickly in the direction of arrow C, and the electromagnetic valve 34 can be closed in a short time. In other respects, the same effects as in the embodiment shown in FIG. 1 can be obtained.

According to the present invention, as described above, during the operation standby period of the solenoid valve, an excitation current is intermittently supplied in response to a signal from a switch that is activated depending on the position of the valve body to open and/or close the valve. The valve state is maintained in the state just before entering the valve state, and in this state, the valve disc is placed in a state where it vibrates slightly in the vicinity of its critical position, so that the valve disc is not affected by the valve closing or opening command signal. In response, the solenoid valve can be moved to a predetermined position extremely quickly, and the solenoid valve can be opened and closed at extremely high speed. Furthermore, the critical position of the valve body during standby is determined mechanically by a switch that operates according to the movement of the valve body, so adjustment is easy, accurate setting, and stable operation can be expected. can.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the electromagnetic valve drive circuit according to the present invention, FIGS. 2a to 2g are waveform diagrams for explaining the operation of the circuit shown in FIG. 1, and FIG. 4 is a circuit diagram showing another embodiment of the electromagnetic valve drive circuit according to the present invention, and FIGS. 4a to 4f are waveform diagrams for explaining the operation of the circuit shown in FIG. 3. 1, 35... Solenoid valve drive circuit, 2, 37... Solenoid coil, 3... Spool valve, 4, 34... Solenoid valve, 5... Switch device, 6, 38... Current control circuit, 26, 49 ...Transistor, 32...Valve seat, 33...Valve body, 36...Switch, SW ₁ ...
1st switch, SW ₂ ... 2nd switch, ST
...Start switch, CP...Control pulse,
CS ₁ ...First control signal, _CS2 ...Second control signal.

Claims (1)

[Claims] 1. In a drive circuit for a solenoid valve configured to perform opening and closing operations by a valve body positioned in accordance with an excitation current applied to an electromagnetic coil, the valve body starts switching the solenoid valve to open and close. an on/off switch means connected to the valve body so that the operating state is changed from the previous required valve body position, and in response to the on/off switch means, the valve body changes to the desired valve body position. An electromagnetic valve drive circuit comprising: energization control means for applying an excitation current to the electromagnetic coil to move the valve element toward the desired valve element position until the valve element is moved toward the desired valve element position.