JP4230824B2 - Energization control device for latch type solenoid valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an energization control device for controlling a valve current of a latch type electromagnetic valve.
[0002]
[Prior art]
Conventionally, as solenoid valves for automatic faucets and toilet flushing devices, latch-type solenoid valves that hold the plunger open after energization and the closed state after closing are widely used. ing.
FIG. 5 shows a specific example thereof.
[0003]
In FIG. 5, reference numeral 200 denotes a pilot water passage, and the water passage 200 a communicates with the back pressure chamber 206 on the back side of the main valve 204 that opens and closes the main water passage 202, and the water passage 200 b is the main valve of the main water passage 202. It communicates with the downstream side 202b from 204.
[0004]
When the pilot water passage 200 is shut off, that is, closed, the water pressure in the back pressure chamber 206 that is in communication with the upstream side 202a of the main water passage 202 with respect to the upstream side 202a is increased and the main valve 204 is closed. When the water channel 200 is opened, the water pressure in the back pressure chamber 206 is reduced, the main valve 204 is opened, and the main water channel 202 is in communication.
[0005]
A plunger 208 is slidably fitted to the inner peripheral surface of a sleeve (guide cylinder) 210. The seating of the plunger 208 on the valve seat 212 blocks the pilot water passage 200, and the valve seat 212. The pilot water passage 200 is in a communication state due to the separation from the pilot water passage.
[0006]
Inside the sleeve 210, a fixed core 214 is provided in a fixed position at a predetermined interval from the plunger 208. A spring 216 is interposed between the plunger 208 and the fixed core 214, and the plunger 208 is constantly springed in the closing direction (upward in the figure) by the spring 216.
[0007]
A ring-shaped permanent magnet 218 and ring-shaped plates 220 and 222 made of a magnetic material are sandwiched in the axial direction on the outside of the sleeve 210, and the lower side (in the figure) On the lower side, a solenoid 224 is provided so as to surround the fixed core 214. These are fixed to a main body 228 such as a faucet through a yoke 226.
[0008]
The permanent magnet 218 is magnetized in the thickness direction, and the magnetic flux returns to the permanent magnet 218 through the ring-shaped plate 220, the plunger 208, the fixed core 214, the yoke 226, and the ring-shaped plate 222.
[0009]
In the latch-type electromagnetic valve 230, even in the closed state shown in FIG. 5, an attractive force toward the fixed core 214 is acting on the plunger 208 by the magnetic flux of the permanent magnet 218. The elastic force of the spring 216 overcomes this suction force and presses the plunger 208 against the valve seat 212.
[0010]
In this state, if a valve current that causes the solenoid 224 to generate a magnetic flux in the same direction as that of the permanent magnet 218 is passed (when energized), the attractive force of the fixed core 214 overcomes the elastic force of the spring 216. The plunger 208 is sucked toward the fixed core 214 side.
[0011]
Thus, once the plunger 208 starts to move, the gap between the plunger 208 and the fixed core 214 decreases, so that the suction force increases and the plunger 208 abuts against the fixed core 214 and becomes stronger. Adsorbed and held.
[0012]
Here, the latch type electromagnetic valve 230 is opened, the pilot water passage 200 is in communication, the main valve 204 is opened, and the main water passage 202 is in communication, and water is discharged from the water outlet.
[0013]
As described above, an attractive force based on the magnetic flux of the permanent magnet 218 is exerted between the plunger 208 and the fixed core 214, and this attractive force is applied to the spring 216 in a valve-open state in which only a small gap exists between them. The plunger 208 is held in the attracted state by the fixed core 214 even if the energization to the solenoid 224 is stopped after the valve is opened because it is strong enough to overcome the elastic force (set as such). That is, the latch type electromagnetic valve 230 is held in an open state, and the water flow in the main water passage 202 continues to flow.
[0014]
Next, in order to close the pilot water passage 200, when a valve current in the opposite direction to the solenoid 224 is passed (when off-energization is performed), the magnetic flux generated by the permanent magnet 218 is canceled, thereby causing the plunger 208 to move to the spring 216. After being separated from the fixed core 214 by the elastic force, the pilot water passage 200 is closed by being pressed against the valve seat 212.
[0015]
When the pilot water passage 200 is closed, the water pressure in the water passage 200a and the back pressure chamber 206 communicating with the water passage 200a is increased, the main valve 204 is closed, and the water flow in the main water passage 202 is stopped.
[0016]
In the case of this latch-type electromagnetic valve 230, it is necessary to pass the valve current only during the valve opening operation and the valve closing operation, and thereafter it is not necessary to pass the valve current, so that power saving can be achieved.
[0017]
By the way, in this latch type electromagnetic valve 230, the timing to stop energization of the valve current to the solenoid 224 becomes a problem.
If the timing is too early, a malfunction of the plunger 208 is caused, and conversely, if the timing is too late, power is unnecessarily consumed.
[0018]
Thus, in order to stop the energization of the valve current at an appropriate timing, it is necessary to detect that the plunger 208 has moved to its end position.
If it is possible to detect that the plunger 208 has moved to its end position, it is possible to stop energization of the valve current at an appropriate timing, and it is possible to supply power without excess or deficiency.
[0019]
Therefore, in the previous patent application (Patent Document 1 below), the present applicant determines whether or not the plunger has moved to the end position by detecting a change in the valve current using a differentiation circuit, and the valve to the solenoid is determined. An energization control device was proposed to stop energizing current.
[0020]
For example, when the plunger 208 moves in the opening direction, that is, in the direction in which it is pulled toward the solenoid 224, the valve current flowing through the solenoid 224 rises gradually to a peak without suddenly rising as shown in FIG. Reach.
When the plunger 208 starts moving, the impedance of the solenoid 224 rises and changes, so that the valve current once decreases after exceeding the peak, and when the plunger 208 moves to the end position, the valve current starts to rise again.
[0021]
Therefore, in the energization control device of Patent Document 1, a differential circuit is used to detect a change in the valve current signal, specifically, an increase in the voltage generated in proportion to the valve current, and a differential wave is output. The comparison circuit compares the magnitude of the differential wave with a reference value, and when a differential wave exceeding the reference value is generated for the second time, it is determined that the plunger 208 has moved to the end position, and the solenoid 224 The energization is stopped.
[0022]
FIG. 6B shows the waveform of the differential wave. ₁ Indicates the differential wave when the valve current increases for the first time, B ₂ Represents a differential wave when the valve current increases for the second time. A chain line C represents a reference value (threshold value) set in the comparison circuit at the subsequent stage.
FIG. 6C shows a pulse signal output from the comparison circuit. ₁ Is the first pulse signal, P ₂ Represents the second pulse signal.
[0023]
FIG. 7 shows a specific circuit configuration example of the energization control device.
In the same figure, 224 is a solenoid of the latch type solenoid valve 230, 232 is a driving power source of the solenoid 224, 234 is a sensor for detecting a human body, 236 is a microcomputer, and 238 is an H bridge circuit as a driving circuit of the solenoid 224. Transistors Tr1 and Tr2 and NPN transistors Tr3 and Tr4, which are H-bridge connected.
[0024]
R14 is a resistor that generates a voltage proportional to the valve current flowing through the solenoid 224, and the voltage generated by the resistor R14 is differentiated by a differentiating circuit 240 provided in a subsequent stage.
The differentiating circuit 240 is composed of a capacitor C4 and a resistor R16, and its output is input to the non-inverting input terminal of the operational amplifier OP1.
That is, the differential wave of the differentiation circuit 240 is amplified by the operational amplifier OP1.
[0025]
Thus, the amplified differential wave is input to the non-inverting input terminal of the operational amplifier OP2 in the comparison circuit 242.
A voltage obtained by resistance division is input as a reference value (threshold value) to the inverting input terminal of the operational amplifier OP2. If the output value from the operational amplifier OP1, that is, the differential wave is larger than the reference value, this value is obtained. The H signal is input from the comparison circuit 242 to the microcomputer 236 as a pulse signal.
On the other hand, if the output value from the operational amplifier OP1 is smaller than the reference value, the L signal is input from the comparison circuit 242 to the microcomputer 236.
[0026]
The microcomputer 236 generates a differential wave larger than the reference value in the differentiation circuit 240 by the supply of the H signal from the comparison circuit 242, specifically, the second supply of the H signal, that is, the second time of the valve current. Knowing that the rise has occurred, it is determined that the plunger 208 has moved to the end position, the H bridge circuit 238 as the drive circuit of the solenoid 224 is turned off, and the valve current from the drive power supply 232 to the solenoid 224 is energized. Stop.
[0027]
When the plunger 208 in the open position is moved in the closing direction, that is, when the plunger 208 is protruded upward in FIG. 5 from the solenoid 224 side, a valve current in the opposite direction to the solenoid 224 is supplied.
At this time, the valve current gradually rises as shown in FIG. 8A, draws a gentle curve, becomes saturated, and the valve current does not decrease midway.
[0028]
When the plunger 208 is moved in the closing direction, the differential wave B shown in FIG. ₃ Will occur.
And this differential wave B ₃ Based on this, the comparison circuit 242 outputs a wide pulse signal P shown in FIG. ₃ Is output, and the microcomputer 236 outputs the pulse signal P ₃ The valve closing signal is output at the fall timing of the valve, and the energization of the valve current from the drive power source 232 to the solenoid 224 is stopped.
[0029]
[Patent Document 1]
JP 2003-21257 A
[0030]
[Problems to be solved by the invention]
However, the following facts became clear as the inventors conducted further research.
That is, the waveform of the valve current shown in FIG. 6A is obtained when the plunger 208 smoothly moves from the start end position to the end position. In practice, the movement of the plunger 208 is temporarily irregular in the process of moving. As a result, it has been found that there is a possibility of moving to the end position through such irregular movement.
[0031]
The reason for this is not necessarily clear, but it is thought that such various factors as the impact of water, the force relationship with the spring 216, and the movement of fine dust and the like together are affected.
In any case, if the plunger 208 performs an irregular movement with such rattling, the valve current also becomes irregular.
[0032]
FIG. 9A shows the waveform of the valve current when the plunger 208 moves with such irregular motion.
As shown in the figure, the valve current once decreases after reaching a peak, and rises halfway along with the rattling motion of the plunger, and further draws a curve that rises again through the inflection point.
[0033]
At this time, the differential wave B when the valve current first starts to rise from the differential circuit 240 in the energization control device of the above-mentioned Patent Document 1. ₁ Subsequently, the second differential wave B shown in FIG. 9B when the plunger 208 starts to move again after being half-stopped by a half-movement. ₄ When the plunger 208 is completely moved to the end position, the differential wave B is further generated. ₂ Is output.
[0034]
In this case, the differential wave B after amplification by the operational amplifier OP1 ₄ Is larger than the reference value of the comparison circuit 242, the pulse signal P shown in FIG. ₄ Is output, and its pulse signal P ₄ As a result, the microcomputer 236 erroneously determines that the plunger 208 has reached the end position, and stops energizing the valve current there.
As a result, the plunger 208 malfunctions due to an early stop of energization.
[0035]
However, the pulse signal P when the plunger 208 starts moving again after being half-moved and half-stopped. ₄ It is also conceivable that the valve current is not stopped immediately and the valve current is stopped after a certain margin time.
However, in this case, if the safety time is taken into consideration and the allowance time is increased, the effect of reducing the power will be reduced.
[0036]
After that, even if the valve current is continuously applied for a certain time, the differential wave B output when the plunger 208 is completely moved. ₂ Since this becomes small, this differential wave B ₂ Cannot exceed the reference value C, and it becomes impossible to determine the energization stop timing of the valve current.
In this case, it is conceivable to lower the reference value, that is, the threshold value in the comparison circuit 242, but it is actually difficult to lower the reference value.
[0037]
In the differential amplifier circuit using the operational amplifier OP1 of FIG. 7, the entire base potential level of the differential waveform of the differential circuit 240 input to the operational amplifier OP1 is greatly amplified by the operational amplifier OP1 and output by the offset voltage of the operational amplifier OP1. Therefore, if the reference value is set low by the comparison circuit 242 at the subsequent stage, the base voltage level of the differential waveform is output as a large value and exceeds the reference value due to the offset voltage, and the differential wave B ₂ Even if no signal occurs, the comparison circuit 242 outputs a pulse signal, and the differential wave B ₂ It is because it becomes impossible to detect correctly.
[0038]
[Means for Solving the Problems]
The energization control device for the latch type solenoid valve of the present invention has been devised to solve such problems.
Thus, according to the first aspect, the plunger is moved in the opening direction or the closing direction by the electromagnetic force by energizing the valve current to the solenoid, and the energization is stopped after the movement, and With power off In the energization control device of the latch type solenoid valve that holds the plunger in position, the change in the valve current is detected. And After the valve current has decreased beyond the first peak, it has again increased substantially to the first peak. Current change detecting means for detecting, Thus, power supply to the solenoid is stopped.
[0039]
According to a second aspect of the present invention, in the first aspect, the energization control device determines a terminal position of the movement of the plunger in the pull-in direction toward the solenoid side by detecting a change in the valve current by the current change detection means. However, the power supply is stopped.
[0040]
According to a third aspect of the present invention, in any one of the first and second aspects, the current change detection means compares the differentiation circuit for differentiating the valve current signal and the magnitude of the differential wave from the differentiation circuit with a reference value. A differentiating circuit, wherein the differentiating circuit ignores the change in the valve current after the valve current exceeds the first peak and then substantially rises again to the first peak. When the comparison circuit detects that a differential wave larger than the reference value is generated for the second time from the differentiation circuit, the plunger is moved to the end position. It is characterized in that the power supply is stopped as it has reached.
[0041]
According to a fourth aspect of the present invention, in the third aspect, the differentiation circuit includes a negative feedback differential amplifier circuit using a single power source operational amplifier in which a positive power source is connected to a positive power source terminal and a negative power source terminal is grounded. The voltage generated in proportion to the valve current is input to the non-inverting input terminal of the operational amplifier, and connected to the inverting input terminal side of the operational amplifier. The capacitor is connected to the negative power supply terminal of the operational amplifier.
[0042]
[Operation and effect of the invention]
As described above, the present invention determines that the plunger has moved to the end position at the time when the valve current flowing through the solenoid decreases beyond the first peak and then substantially increases again to the first peak. The solenoid is de-energized.
[0043]
The inventors have found that even if the plunger has rattled in the process of movement and stops halfway when it has moved halfway, the valve current will increase to the first peak after decreasing. The experiment confirmed the fact that has been moved to its end position.
The present invention has been made based on such findings.
[0044]
Thus, according to the present invention, even if the plunger is rattled in the course of movement and stops halfway, the plunger can be reliably moved to the end position. It is possible to prevent a malfunction due to the stoppage.
Moreover, it is possible to avoid wasteful consumption of electric power by keeping the one-way valve current flowing unnecessarily long, thereby realizing original power saving.
[0045]
In the present invention, the terminal position of the movement of the plunger in the retracting direction toward the solenoid can be determined by detecting the current change, and the valve current can be stopped.
[0046]
In the present invention, the current change detecting means can be configured as follows.
That is, a differential circuit that differentiates the valve current signal and a comparison circuit that compares the magnitude of the differential wave from the differential circuit with a reference value are configured, and the differential circuit is configured so that the valve current exceeds the first peak. From then on, it is possible to ignore the change in the valve current and not produce a differential wave until it rises to the first peak again.
In the energization control device provided with such a current change detection means, when the comparison circuit detects that the differential wave larger than the reference value is generated for the second time from the differential circuit, it is assumed that the plunger has reached the end position. The current is turned off (claim 3).
[0047]
In this case, the differential circuit includes a negative feedback differential amplifier circuit using a single power supply operational amplifier in which a positive power supply is connected to the positive power supply terminal and the negative power supply terminal is grounded, and is proportional to the valve current. The voltage generated in this way is input to the non-inverting input terminal of the operational amplifier, while the capacitor connected to the inverting input terminal side can be connected to the negative power supply terminal of the operational amplifier.
[0048]
When the differential circuit is configured in this way, the offset voltage of the differential amplifier circuit using the operational amplifier can be substantially ignored, and therefore the reference value of the comparison circuit provided in the subsequent stage can be lowered. Thus, even a minute increase in valve current, that is, a small differential wave can be detected with high accuracy.
According to the fourth aspect, the differentiation circuit can be configured with a simple and inexpensive circuit.
[0049]
【Example】
Next, when the present invention is applied to the energization control device of the latch type electromagnetic valve in the water supply device that detects the human body with the sensor and starts water supply based on the human body detection while stopping the water supply when the sensor becomes non-detected by the human body Embodiments will be described in detail below with reference to the drawings.
[0050]
In FIG. 1, 10 is a solenoid of a latch-type electromagnetic valve, 12 is a power source for driving, 14 is a sensor for detecting a human body, and 16 is a microcomputer.
Reference numeral 18 denotes an H bridge circuit as a drive circuit for the solenoid 10, and a differential circuit (differential amplification circuit) 20 for performing a differential operation by inputting a voltage output in proportion to the valve current to the subsequent stage, and further performing a differential operation on the subsequent stage. A comparison circuit 22 that compares the output from the circuit 20 with a reference value (threshold value) and outputs the comparison result is connected.
[0051]
Here, the H bridge circuit 18 has PNP type transistors Tr1 and Tr2 and NPN type transistors Tr3 and Tr4, which are H bridge connected.
Specifically, a circuit in which the collector of the PNP transistor Tr1 and the collector of the NPN transistor Tr3 are connected in series, and similarly, the collector of the PNP transistor Tr2 and the collector of the NPN transistor Tr4 are connected in series. Are connected in parallel, and a resistor R14 is connected in series to the parallel circuit.
Here, the resistor R14 is a resistor for detecting the valve current, that is, a resistor for generating a potential difference corresponding to the valve current at both ends.
[0052]
An intermediate point between the transistors Tr1 and Tr3 is connected to one terminal 1 side of the solenoid 10, and an intermediate point between the transistors Tr2 and Tr4 is connected to the other terminal 2 side of the solenoid 10.
The base side of the transistor Tr1 is connected to the terminal 2 side of the solenoid 10 via the resistor R1, and is connected to the plus side of the power source 12 via the resistor R2.
The base side of the transistor Tr2 is connected to the terminal 1 side of the solenoid 10 via a resistor R4, and is connected to the plus side of the power source 12 via a resistor R3.
[0053]
Further, the base side of the transistor Tr3 is connected to the output terminal OUT3 of the microcomputer 16 via the resistor R9, and the base side of the transistor Tr4 is connected to the output terminal OUT4 of the microcomputer 16 via the resistor R10.
[0054]
The intermediate point between the H-bridge circuit 18 of the transistors Tr1 to Tr4 and the resistor R14 is connected to the non-inverting input terminal of the operational amplifier OP1 in the subsequent differentiation circuit 20 via the resistor R16, and the valve current flows through the resistor R14. , That is, a voltage proportional to the valve current is input to the non-inverting input terminal of the operational amplifier OP1.
[0055]
This differentiation circuit 20 is composed of an operational amplifier OP1 as a main element. As shown in FIG. 2, a resistor R7 and a resistor R6 are connected to a feedback circuit K that feeds back its output to the inverting input terminal of the operational amplifier OP1. Has been.
[0056]
A capacitor C1 is connected to the feedback circuit K in parallel with the resistor R7.
One terminal of the capacitor C2 is also connected to the resistor R6.
The other terminal of the capacitor C2 is connected to the negative power supply terminal of the operational amplifier OP1 and is grounded.
In this example, the operational amplifier OP1, resistors R7 and R6, and capacitors C2 and C1 constitute a differentiation circuit 20 as a whole.
The capacitor C1 is mainly used for removing noise.
[0057]
In this example, the operational amplifier OP1 has the negative power supply terminal connected to the capacitor C2 and grounded as described above, and the positive power supply OUT2 (VCC) connected to the positive power supply terminal.
That is, the operational amplifier OP1 performs a single power supply operation here.
The output side of the operational amplifier OP1 is grounded through a resistor R17, and is connected through a resistor R11 to a non-inverting input terminal of the operational amplifier OP2 in the comparison circuit 22 at the subsequent stage.
[0058]
The voltage obtained by dividing the power supplied through the microcomputer 16 by resistors R5 and R8 is input to the inverting input terminal of the operational amplifier OP2 in the comparison circuit 22 as a reference value (threshold value). The voltage value inputted from the operational amplifier OP1 of the differentiating circuit 20 to the non-inverting input terminal of the operational amplifier OP2 is compared with the reference value, and the result is outputted as a digital signal of H (High) or L (Low). ing.
The output of the operational amplifier OP2 is fed back to the non-inverting input terminal of the operational amplifier OP2 through the resistor R12.
The output signal from the operational amplifier OP2 is input to the input terminal IN2 of the microcomputer 16.
[0059]
Here, the operational amplifier OP2 outputs an H signal (pulse signal) when the input voltage value to the non-inverting input terminal, that is, the output voltage value from the differentiation circuit 20 is larger than the reference value applied to the inverting input terminal, and outputs the microcomputer 16 If the opposite is true, the L signal is output to the microcomputer 16.
[0060]
The sensor 14 is supplied with power from the output terminal OUT1 of the microcomputer 16, and the signal from the sensor 14 is input to the microcomputer 16 at the input terminal IN1.
In FIG. 1, D1 to D5 each represent a diode.
[0061]
Next, the operation of the apparatus of this example will be described below.
In this example, when the sensor 14 senses a human body, a sensing signal is input to the input terminal IN1 of the microcomputer 16.
As a result, the microcomputer 16 turns on the operational amplifiers OP1 and OP2 through the output terminal OUT2, and turns on the transistor Tr4 through the output terminal OUT4 to make it conductive. At this time, the transistor Tr3 remains off.
[0062]
When the transistor Tr4 is turned on, the transistor Tr1 is also turned on, and current flows from the emitter side to the collector side of the transistor Tr1 and further from the collector side to the emitter side of the transistor Tr4.
That is, here, a valve current flows from the terminal 1 side to the terminal 2 side through the solenoid 10, whereby the plunger moves in the opening direction, that is, in the retracting direction by the solenoid 10, and the electromagnetic valve starts to open.
[0063]
The valve current flowing through the solenoid 10 flows through the resistor R14.
At this time, a voltage having a magnitude proportional to the valve current is generated at both ends of the resistor R14, and the voltage is input to the non-inverting input terminal of the operational amplifier OP1 in the differential circuit 20 at the subsequent stage via the resistor R16.
The differentiation circuit 20 differentially amplifies the input voltage that changes in accordance with the valve current, and inputs the output to the non-inverting input terminal of the operational amplifier OP2 in the comparison circuit 22.
[0064]
The comparison circuit 22 determines whether the generated differential wave is larger or smaller than the reference value, and supplies the H signal as a pulse signal when it is large, and supplies the L signal to the microcomputer 16 when it is small. In response to this, the microcomputer 16 stops driving the H bridge circuit 18 by the second pulse signal.
Specifically, an off signal is output through the output terminal OUT4 to turn off the transistors Tr4 and Tr1.
[0065]
As described above, when the plunger is moved in the opening direction, the valve current flowing through the solenoid 10 gradually increases and reaches a peak, and then the valve current temporarily decreases due to the impedance change of the solenoid 10 accompanying the movement of the plunger.
[0066]
Accordingly, at this time, the input voltage having a magnitude proportional to the valve current applied to the differentiating circuit 20 is input to the non-inverting input terminal of the operational amplifier OP1 in a waveform corresponding to the change in the valve current.
A solid line in FIG. 3A shows a change in voltage input to the non-inverting input terminal of the operational amplifier OP1, that is, a voltage waveform thereof.
[0067]
The amplification factor of the differential amplifier circuit in which the output of the operational amplifier OP1 is fed back to the inverting input terminal by the feedback circuit K is expressed as (Z + R7) / Z, where Z is the impedance of the resistor R6 and the capacitor C2.
Here, in a situation where the impedance of the capacitor C2 can be ignored when charging the capacitor C2, if the resistance value of the resistor R6 is 10 kΩ and the resistance value of R7 is 2 MΩ, the amplification factor of the differential amplifier circuit is about 200 times. It becomes.
[0068]
At this time, that is, when the valve current rises, as shown by the solid line arrow in FIG. 2, a relatively large charging current flows from the output side of the operational amplifier OP1 to the capacitor C2 side through the feedback circuit K to the left in the figure, and the capacitor C2 Will be charged quickly.
[0069]
At this time, the voltage on the inverting input terminal side of the operational amplifier OP1 rises as the voltage at the non-inverting input terminal increases while maintaining the same potential as the voltage at the non-inverting input terminal. The operational amplifier OP1 performs an output operation so that the difference between the potential of the inverting input terminal and the potential of the non-inverting input terminal is maintained at 0V.
[0070]
By the way, in this differential amplifier circuit, when the charging current of the capacitor C2 flows through the feedback circuit K in the left direction in the drawing and the charging of the capacitor C2 proceeds, and the resistance (impedance) of the capacitor C2 increases accordingly, Along with this, the amplification factor of the differential amplifier circuit gradually decreases.
When the charging of the capacitor C2 is completed, the resistance by the capacitor C2 becomes infinite, and the amplification factor of the differential amplifier circuit finally converges to 1.
[0071]
FIG. 3B shows a change in the output of the operational amplifier OP1 in accordance with the change in the amplification factor. That is, this is nothing but the amplified differential waveform output from the operational amplifier OP1.
That is, the output of the operational amplifier OP1 rises rapidly at the initial stage when the charging current flows through the capacitor C2, and then the output decreases as the charging progresses. As a result, the output waveform becomes a differential waveform.
[0072]
The differentiating circuit 20 performs the differentiating operation again after the valve current once decreases, that is, after the input voltage applied to the non-inverting input terminal of the operational amplifier OP1 once decreases and then rises again and substantially reaches the first peak. In the meantime, the differential operation is not substantially performed.
This is due to the following reason.
[0073]
When the input voltage applied to the non-inverting input terminal of the operational amplifier OP1 starts to decrease beyond the peak, the potential of the inverting input terminal of the operational amplifier OP1 temporarily becomes higher than that of the non-inverting input terminal.
In a normal operational amplifier using two power sources, a positive power source and a negative power source, a negative voltage is applied from the output side so as to keep the potential of the inverting input terminal at the same potential as that of the non-inverting input terminal, that is, to maintain an imaginary short. Is output.
Then, the negative voltage output causes the capacitor C2 to quickly discharge the feedback circuit K by the rightward discharge current indicated by the dashed arrow in FIG. 2, and to quickly reduce the potential of the inverting input terminal of the operational amplifier OP1.
[0074]
However, in this example, the operational amplifier OP1 is a single power source that uses only the positive power source, and the capacitor C2 and the negative power source terminal of the operational amplifier OP1 are connected and grounded, so that a negative voltage is output from the operational amplifier OP1. Not.
As a result, the imaginary short of the operational amplifier OP1 is not established, and the discharge of the capacitor C2 is delayed, and the potential of the inverting input terminal of the operational amplifier OP1 cannot temporarily follow the decrease of the potential of the non-inverting input terminal.
[0075]
As a result, the potential of the inverting input terminal of the operational amplifier OP1 changes substantially horizontally after exceeding the peak as shown by the broken line in FIG. 3A (however, it slightly falls to the right in the figure).
That is, the input voltage applied to the non-inverting input terminal of the operational amplifier OP1 is first changed as shown by the solid line in FIG. Even if it decreases after exceeding the peak and then rises again, the potential on the inverting input terminal side cannot follow this due to the delay of the discharge of the capacitor C2, and the input voltage at the non-inverting input terminal is as shown by the broken line. It shows the same behavior as when it changed.
[0076]
That is, the differential circuit 20 does not output a differential wave corresponding to the voltage rise that occurs when the plunger is moved again after being semi-stopped, and the voltage at the non-inverting input terminal substantially reaches the first peak again. When the time is exceeded, the imaginary short circuit is established again, and the next differential wave is generated only there.
[0077]
Specifically, as shown in FIG. 3 (B), the differentiation circuit 20 increases again after the valve current (strictly speaking, the voltage corresponding thereto) decreases beyond the first peak, and substantially increases to the first When the peak is exceeded, the second differential wave B ₂ Is output.
[0078]
As described above, when the valve current once decreases and then recovers to the first peak, even if the plunger moves halfway or stops halfway, most of it moves to the end position. This fact has been confirmed by experiment, and therefore this second differential wave B ₂ Pulse signal P as a determination result from the comparison circuit 22 at the subsequent stage at the rise of ₂ By outputting (H signal) and stopping the energization of the valve current, the plunger can be reliably moved to the end position. In addition, this can prevent unnecessary power supply from being wasted.
[0079]
The above is the operation when the plunger is moved in the opening direction. The operation when the plunger is moved in the closing direction by non-detection of the human body by the sensor 14 is as follows.
[0080]
That is, the microcomputer 16 outputs a signal from the output terminal OUT3 according to the signal from the sensor 14.
By this signal, the transistor Tr3 is turned on, and then the transistor Tr2 is turned on, and the solenoid 10 is energized with a valve current in the direction opposite to that when the valve is opened.
[0081]
The valve current at this time does not decrease midway, rises while drawing a curve, and finally saturates.
The energization stop based on the detection of the change in the valve current is the same as that of the conventional energization control device shown in FIG.
[0082]
In the energization control device of the present example as described above, even if the plunger is semi-stopped due to rattling motion, the plunger can be reliably moved to the end position, It is possible to prevent malfunction due to stoppage due to movement.
Moreover, it is possible to avoid wasteful consumption of electric power by keeping the one-way valve current flowing unnecessarily long, thereby realizing original power saving.
[0083]
In the energization control device of this example, since the amplification factor of the differential amplifier circuit including the operational amplifier OP1 finally converges to 1, that is, the amplification factor of the base potential level of the differential waveform becomes 1, so that the operational amplifier OP1 The offset voltage can be substantially ignored.
Therefore, according to this example, the reference value in the comparison circuit 22 at the next stage can be set low, and even if the second differential wave from the comparison circuit 22 is small to some extent, it can be detected with high accuracy. Is possible.
[0084]
Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention provides the connection position of the capacitor C2 and the resistor R6 as shown in FIG. 4 in the differentiation circuit 20 of the above embodiment, for example. For example, the position may be different from the above example, and various modifications may be made without departing from the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram showing an energization control device for a latch type solenoid valve according to an embodiment of the present invention together with peripheral portions.
FIG. 2 is an enlarged view showing a main part of FIG.
FIG. 3 is an operation explanatory diagram of an energization control device according to the embodiment.
FIG. 4 is a diagram showing another embodiment of the present invention.
FIG. 5 is a view showing an example of a latch-type solenoid valve that has been conventionally used.
FIG. 6 is an operation explanatory view of a conventionally known energization control device shown for explaining the background of the present invention.
FIG. 7 is a diagram showing a conventional energization control device for a latch type solenoid valve together with peripheral portions.
8 is an operation explanatory view different from FIG. 6 of the energization control device of FIG.
FIG. 9 is an explanatory diagram of a problem with the energization control device of FIG. 7;
[Explanation of symbols]
10 Solenoid
20 Differentiation circuit (differential amplification circuit)
22 Comparison circuit
C reference value
B ₁ , B ₂ Differential wave
OP1, OP2 operational amplifier
C2 capacitor
VCC plus power supply

Claims (4)

In the energization control device of the latch type solenoid valve that moves the plunger in the opening direction or the closing direction by electromagnetic force by energizing the valve current to the solenoid, stops energization after the movement , and holds the plunger in the energized stop state .
A current change detecting means for detecting a change in the valve current , and detecting a time point when the valve current decreases to exceed the first peak and then substantially increases to the first peak again ; Thus, the energization control device for the latch-type solenoid valve, wherein the energization to the solenoid is stopped.   2. The energization control device according to claim 1, wherein the energization control device determines an end position of movement of the plunger in the pulling direction toward the solenoid side by detecting a change in the valve current by the current change detecting means, and stops energization. There is provided an energization control device for a latching solenoid valve.   The current change detection means according to claim 1, further comprising: a differentiation circuit that differentiates the valve current signal; and a comparison circuit that compares the magnitude of the differential wave from the differentiation circuit with a reference value. The differential circuit ignores the change in the valve current and does not generate a differential wave during the period from when the valve current exceeds the first peak to the time when the valve current rises to the first peak again. The energization control device determines that the plunger has reached the end position when the comparison circuit detects that the differential wave larger than the reference value is generated from the differentiation circuit for the second time. An energization control device for a latch-type electromagnetic valve, characterized in that   4. The differential circuit according to claim 3, wherein the differential circuit includes a negative feedback differential amplifier circuit using a single power operational amplifier in which a positive power source is connected to a positive power source terminal and a negative power source terminal is grounded. While a voltage generated in proportion to the valve current is input to the non-inverting input terminal of the operational amplifier, a capacitor connected to the inverting input terminal side of the operational amplifier as a component of the differentiation circuit is a negative power source of the operational amplifier An energization control device for a latching solenoid valve, wherein the energization control device is connected to a terminal.

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