JPH05211105A - Check method for solenoid plunger position - Google Patents

Abstract

PURPOSE:To enable checking, on occasion, the position of a plunger after a solenoid is turned OFF, improve the reliability of check results, and make it unnecessary to contain a mechanical switch or the like in the solenoid. CONSTITUTION:A resistor 15 for current detection is connected in series with a coil 11 of a solenoid. The coil 11 is electrified to excite during a time width so short that the moving-core scarcely moves. By detecting the change amount of response waveform of a current flowing through the coil 11 detected by an amplifier 18 from both ends of the resistor 15 for current detection, a recognition part 32 recognizes the position of the moving core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of checking a movable iron core position of a solenoid such as an electromagnetic valve or an electromagnetic plunger, and more particularly to a method of checking a return state when the solenoid is turned off.

[0002]

2. Description of the Related Art For example, a solenoid valve as shown in FIG.
A spool 3 is slidably provided in a slide hole 2 formed in a body 1, and springs 6 and 7 provided in spring chambers 4 and 5 on both sides of the spool 3 cause the spool 3 to move to the rightward position (port P When the solenoid 10 fixed to one end of the body 1 is energized by energizing the coil 11, the movable core 12 is moved according to the magnitude of the exciting current. Moves to the left due to the suction force between the fixed iron core 14 and the spool 3 by the push rod 13.
To the left to bring the ports PA and TB into communication with each other.

FIG. 17 shows the reaction force (solid line a) of the spring 6 in this case and the force resulting from applying a fluid force thereto (dashed line b).
And the output of the solenoid 10 (solid line c).
However, when the spool 3 causes a sticking phenomenon due to clogging of foreign matter or when the movable iron core 12 of the solenoid 10 comes into close contact with the inside of the sliding sleeve, the solenoid output indicated by the solid line c is obtained at the initial (rightward end) position. Even when the obtained exciting current is supplied to the coil 11, the movable iron core 12 does not move to the left, or the exciting current is reduced so that the solenoid output is reduced by ΔF (= spring force + fluid force) at the adsorption (leftward end) position. Even if the number decreases, the movable core 12 may not be separated from the suction position.

A conventional method for checking the operating state of such a solenoid is, for example, Japanese Patent Laid-Open No. 1-2655.
As seen in Japanese Patent Publication No. 04-04, there is known a method of detecting the operating state of a movable iron core from the difference in the current response waveform depending on the moving state of the movable iron core when the solenoid is turned on or off. The operation check when the solenoid is off by this method will be briefly described with reference to FIGS. 18 and 19.

As shown in FIG. 18, the coil 1 of the solenoid
When the current detection resistor 15 is connected in series to 1 and the current is passed through the series circuit by turning on the switch 17 from the power supply 16, the magnitude of the exciting current flowing in the coil 11 is converted into a voltage by the resistor 15. Although it is detected, the operation when the solenoid is ON can be checked by utilizing the fact that the response waveform differs depending on whether or not the movable iron core moves.

When the switch 17 is turned from ON to OFF (time point t1 in FIG. 19), the energy stored in the coil 11 causes the polarity opposite to that of the power supply voltage as shown in FIG. Spike voltage is generated. This voltage is passed through a limiter 19 to remove a voltage equal to or lower than a predetermined voltage and the amplifier
When amplified at 8, a constant negative voltage is output until time t2 as shown in (b) of the same figure.

When the movable iron core starts to return at this time t2, the impedance of the coil 11 changes, which delays the convergence of the spike voltage. And time t3
When the return of the movable core is completed at, the impedance change disappears and the spike voltage rapidly converges toward zero. Therefore, the differential waveform by the differentiating circuit 20 in FIG. 18 becomes a positive pulse waveform as shown in FIG.
If the pulse signal shown in (d) of the figure is obtained, the solenoid is normally off.

This signal is ANDed by the AND circuit 23 with the output from the inverter 22 shown in (e) of the figure, and is output as a solenoid OFF detection signal. As described above, many other methods are disclosed in which whether or not the movable iron core of the solenoid moves is determined based on the difference in response waveform of current or voltage. As other methods for checking the movable iron core position of solenoids, many methods have been proposed in which a solenoid has a built-in mechanical limit switch, or a contactless proximity switch or potentiometer is built in and the check signal is used for checking. There is.

[0009]

However, in such a conventional method for checking the movable iron core position of a solenoid, in the former case, attention is paid to the current discharge waveform when the solenoid is OFF, and whether or not the movable iron core is moving is restrained. In order to determine whether or not the movable core has returned from the difference in the discharge waveform depending on whether the movable core is in a stationary state, the solenoid is turned off.
You can only judge when you make F.

Therefore, if it is attempted to confirm whether or not this has been caused by noise, it is necessary to re-energize and turn it off again, but this causes the spool and actuator to move, which is not possible, and the reliability of the check result cannot be guaranteed. The sex was low. Further, particularly in the case of a so-called shockless solenoid valve in which the movable iron core is made hard to move by oil immersion, since the movement of the movable iron core is slow, a large difference in response waveform does not appear, and thus there is a problem in reliability of discrimination.

The latter has certainty, but the mechanical structure is generally complicated, and an extra space is required to house the switches and the like, and the mechanical one has a problem in durability. It was

The present invention has been made in view of the above-mentioned conventional problems. After the solenoid is turned off,
An object of the present invention is to check the position of the movable iron core as needed, the result of the check is highly reliable, and it is not necessary to incorporate a mechanical switch or the like in the solenoid.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is provided with a current detecting resistor connected in series to a coil of a solenoid, and has a short time width such that a movable iron core hardly moves. Provided is a movable iron core position check method for a solenoid that detects the position of a movable iron core by detecting the amount of change in the response waveform of the current flowing through the coil, which is excited by energizing the coil. To do.

The amount of change in the response waveform of the current flowing through the coil may be detected by the waveform change rate, that is, the differential value of the amount of change per unit time. Further, the change amount of the response waveform may be detected at the time of rising by excitation or at the time of falling after excitation.

[0015]

According to the invention, after the solenoid is turned off, the movable iron core of the solenoid is excited for a time width during which the movable iron core hardly moves, and the difference in the response current waveform due to the difference in the solenoid inductance depending on the position of the movable iron core is eliminated. It is possible to determine whether or not the movable core is at a predetermined position (ON suction position, OFF release position, or intermediate position due to some trouble).

After the solenoid is turned off (generally, the operation is completed within 0.1 second), the check can be performed any number of times, so that the reliability is high and monitoring from the controller side is easy. is there. Moreover, since it is not necessary to incorporate a mechanical switch or the like in the solenoid, there are no problems in space and durability.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram of the solenoid movable iron core position checking device according to the first embodiment of the present invention, and the portions corresponding to those in FIG. 18 are designated by the same reference numerals. First, the configuration will be described. A current detecting resistor 15 is connected in series to a coil 11 of a solenoid, and a diode 25 is connected in parallel to the series circuit.
It is made possible to energize the series circuit of the coil 11 and the resistor 15 from 6 through the switch 27.

At this time, the diode 25 is reverse-biased and therefore non-conductive, but when the switch 27 is turned off, a current due to the energy accumulated in the coil 11 flows through the diode 25. The switch 27 is a controlled switch such as a relay switch or an electronic switch, and is ON / OFF controlled by the switch control unit 26 according to the presence or absence of an ON command and an ON signal.

Further, an inverter 3 for inverting the ON command
3, a timer 28 started by its output, a gate circuit 29 that receives a check command P4 after the timer setting time, and a pulse generator 3 that generates an ON signal P1 by the check command P4 that has passed through the gate circuit 29.
0 is set.

Further, an amplifier 18 for amplifying the terminal voltage e of the resistor 15 generated according to the magnitude of the exciting current flowing through the coil 11, and a hold circuit 31 for holding the output voltage e ₁ thereof when the ON signal P ₁ falls. Inverter 34,
The discriminator 32 that compares the hold output eu of the hold circuit 31 with the reference value es to output the discrimination signal P3 ', the inverter 35 that inverts the discrimination signal P3', the output signal P3, the check command P4, and the inverter 34. AND circuit 36 for taking the AND of the output signal P2.

This embodiment is an example of a solenoid off-operation check device, and is a solenoid 10 as shown in FIG.
Is a device for determining whether or not the movable iron core 12 has returned to the initial position farthest from the attracted position attracted by the fixed iron core 14 by demagnetization. The method of checking the movable iron core position of the solenoid according to this embodiment will be described with reference to the time chart of FIG.

First, when the ON command for activating the solenoid is set to "L" as shown in (a) at the time point "a" in FIG. 2, the switch control unit 26 to which the ON command is input turns the switch 27 to "O".
The FF is turned off, so that the power supply from the DC power supply 16 to the coil 11 is cut off. However, the energy accumulated in the coil 11 causes the current to continue flowing through the diode 25 to the coil 11 and the resistor 15 for a short time, and then completely demagnetizes. To be done.

A voltage e corresponding to the value of the current flowing through the coil 11 is generated across the resistor 15, and the output voltage e1 obtained by amplifying the voltage e by the amplifier 18 changes as shown in FIG. On the other hand, when the ON command becomes "L", the output of the inverter 33 becomes "H" and the timer 28 is started. Therefore, the timer time TM1 (set longer than the time required until the voltage e1 becomes 0) is set. ) After that, the output of the timer 28 becomes "H" as shown in FIG.

As a result, the gate circuit 29 opens the gate, receives and outputs the check command P4 having the predetermined time width TM2 shown in (d) of FIG.
The pulse generator 30 is activated at the rising time point b, and the ON signal P1 having the pulse width TM3 is generated as shown in FIG. Only when the ON signal P1 is "H", the switch control unit 26 turns on the switch 27, and the DC power supply 1
The coil 11 is energized from 6 to excite the solenoid for a short time.

Therefore, the pulse width T of this ON signal P1
M3 is set to a short time width such that the movable iron core hardly moves even when the coil 11 is energized to excite the solenoid. At this time, the value of the current flowing through the coil 11 is detected by the voltage e generated across the resistor 15, and the voltage e is amplified by the amplifier 18 and input to the hold circuit 31. In addition, the hold circuit 3 is provided at the rising point b of the check command P4.
Set 1 to start data acquisition.

At the falling time point c of the ON signal P1, the output of the inverter 34 becomes "H" as shown in FIG. 2F, which causes the hold circuit 31 to output the voltage e at that time point.
Hold 1 Therefore, the hold circuit 31
The hold output eu is as shown in FIG. This hold value eu corresponds to the amount of change in the response waveform of the current flowing through the coil 11 at the rising edge due to the excitation during the period TM3, and the inductance L of the coil 11 will be described later.
Becomes smaller and the inductance L changes depending on the position of the movable iron core, and thus the hold value eu indicates position information of the movable iron core.

Therefore, the hold value eu is determined by the discriminator 32.
Then, the position of the movable iron core of the solenoid is determined by comparing with the reference value es, and as shown in FIG.
If so, the discrimination output P3 'is set to "H". This indicates that the movable iron core has normally returned to the initial position. eu
If it is not> es, the discrimination output P3 'becomes "L", indicating that the movable iron core has not returned (remains at the suction position).

In this embodiment, the AND circuit 36 further takes the AND output of the output P3 shown in (i) of FIG. Then, the abnormality detection signal shown in (n) of FIG. Therefore,
As shown in the normal side of FIG. 2, if the movable iron core returns to the normal position and is in the initial position, the abnormality detection signal is not output (low level) as shown in the normal side of FIG. When the movable iron core does not return to the normal state and remains in the adsorption position as shown on the abnormal side in the figure, a pulse-like abnormality detection signal (high level) is output.

After that, when the check command is turned off at the time point d, the hold circuit 31 is reset and eu becomes 0, the abnormality detection signal is not output, and the next check command is waited. After that, when a check command is input again, the solenoid is excited again for a short time as described above, and the position of the movable iron core is checked. In this way, when the solenoid is off, the movable core position can be checked any number of times.

In the above embodiment, the timer 28 is started immediately after the ON command disappears, and the gate circuit 29 is opened after the set time TM1. However, after the ON command disappears, the current value flowing through the coil 11 is changed. Monitor the detection voltage e1 and set it to a preset value (zero level is acceptable)
Alternatively, the timer 28 may be activated when the temperature drops to. When the inductance L of the coil 11 is large, it can be said that it is more reliable to start the timer on the basis of the actual current as described above, rather than setting the time TM1 from the interruption of energization. In that case, the timer set time TM1 may be zero.

By the way, as described with reference to FIGS. 16 and 17, when the solenoid 10 is excited, the movable iron core 12 is attracted to the fixed iron core (pole face) 14, and the spool 6 resists the spring force + fluid force of the spring 6. Although it moves while pushing 3 etc. and is attracted to the fixed iron core 14, if the solenoid output does not exceed the spring force + fluid force even if a current is passed through the coil 11 for a very short period of time to be excited. , The movable iron core does not move.

Alternatively, even if it slightly moves in the suction direction for a moment, it may be in a range where there is no problem in the entire system. Therefore, the pulse width TM of the ON signal should be within this range.
It is necessary to set 3. 3 (a) and (b) are
FIG. 6 is a waveform diagram showing a difference in a current response flowing in the coil 11 by excitation of a pulse width TM3, that is, a voltage response waveform detected by a resistor 15 depending on a movable iron core position.

The inductance L of the coil 11 is the smallest when the movable iron core is at the initial position (the position farthest from the fixed iron core), and the largest when it is at the adsorption position (the position closely attached to the fixed iron core). It changes depending on the position of the movable iron core as shown in (c) of FIG. The amount of change in the voltage waveform during excitation (the amount of rising) due to this inductance L
However, since the inductance is small when the movable core is in the initial position, it rises largely as shown in FIG. 3B, and when it is in the adsorption position, the inductance is large and the amount of rise is small.

Therefore, the voltage e corresponding to this change amount
By detecting u and comparing it with the reference value es, it is possible to determine where the movable core is.
Although an example of binary discrimination has been described, if this value eu is compared with a plurality of reference values having different levels, it is possible to detect the positions of the movable iron core in a plurality of stages and the resolution of position detection is improved. The accuracy can be improved and the degree of abnormality and normality can be detected. If the value eu is detected steplessly, the position of the movable iron core can be continuously measured.

FIG. 4 is a block diagram similar to FIG. 1 showing the second embodiment of the present invention. In this embodiment, hold circuits 37 and 38 for correcting the reference value es and a correction circuit 39 are added to the check device shown in FIG. This is to correct the reference value es in response to a change in 100% current value due to a rise in coil temperature or a change in power supply voltage and obtain a correct detection point.

The hold circuit 37 is set at the rising of the ON command, starts to take in the supply voltage E0 from the DC power supply 16 as input data, and when the ON command becomes "L", the output of the inverter 33 rises. The value is held, and the hold value, that is, the power supply voltage E0 at that time is output to the correction circuit 39. On the other hand, the hold circuit 38 is also set at the rising edge of the ON command, and the amplifier 18
The detection voltage e1 from is started as input data, and when the ON command becomes “L”, the value is held by the rising of the output of the inverter 33, and the hold value eu0 (the coil in the steady state during solenoid operation is The voltage corresponding to the current value flowing in 11) is output to the correction circuit 39.

The correction circuit 39 receives these voltages E0 and e.
The reference value es is corrected according to the value of u0, and the corrected reference value es' is sent to the discriminator 32. The response characteristic of the current flowing through the coil 11 when the switch 27 is turned on is expressed by the following equation (Equation 1).
It is represented by.

[0038]

[Equation 1]

R: internal resistance of the coil 11 + resistance value of the resistor 15 L: inductance of the coil 11 Therefore, the power supply voltage E 0 immediately before the coil current is cut off
Then, by holding the voltage eu0 corresponding to the steady-state current I at that time, the value of R becomes known by R = E0 / I, and it becomes possible to correct the reference value es in accordance with these variations. By this correction, it is possible to improve the accuracy of the determination of the movable iron core position by the determination unit 32.

In each of the above-described embodiments, the case has been described in which the position of the movable iron core is checked by instantaneously exciting the solenoid in the completely demagnetized state, but it is not completely demagnetized, for example, about 50% in the coil 11. It is of course possible to excite so that a current of 100% flows from the state in which the current of (4) flows, and the position of the movable iron core is measured from the amount of change in the instantaneous excitation current waveform from 50% to 100%. It is also possible.

FIG. 5 is a block configuration diagram of a third embodiment using a one-chip microcomputer (hereinafter abbreviated as "microcomputer"). The parts corresponding to those in FIG. 1 are designated by the same reference numerals, Descriptions thereof are omitted. FIG. 6 is a flowchart of the processing by the microcomputer 40.

The microcomputer 40 inputs an ON command and a check command to control ON / OFF of the switch (SW) 27, and internally outputs the output voltage e1 of the amplifier 18 (voltage corresponding to the current value flowing through the coil 11). The A / D conversion unit converts the value into a digital value for checking, and when an abnormal operation of the solenoid is detected, an abnormality detection signal is output. In this embodiment, since the external sequencer manages the timing of the ON command and the check command, the interlock means between them becomes unnecessary.

Further, in this embodiment, the voltage dividing resistors R1 and R2 are connected in parallel to the power source 16 via the main switch MS so that the reference value can be corrected as described above, and the voltage dividing point The voltage e0 is also input to the microcomputer 40. The main switch MS is a manual switch that is always turned on while using the solenoid.

Next, the processing by the microcomputer 40 will be described with reference to FIG. This is a process when the reference value es is not corrected, and when this routine starts,
The presence or absence of an ON command is checked, and if there is (if it is "H"), then it is checked whether or not the switch 27 is ON, and then ON.
If so, the process returns to the beginning as it is, but if it is off, the switch 27 is turned on and the process returns to the beginning.

If there is no ON command in the first ON command presence / absence check, after the switch 27 is turned OFF, a set time (for example, 100 μS) more than the time required for the solenoid OFF operation (return of the movable iron core) has elapsed. Wait for input of check command. O before checking command is input
When the N command is given, the switch 27 is turned on again to energize the coil 11. When a check command is input after 100 μS has elapsed, an ON pulse having a predetermined short pulse width is generated, and the switch 27 is turned ON only during that period.

The A / D conversion value of the output voltage e1 from the amplifier 18 is held at the trailing edge of the ON pulse, and the hold value eu is compared with the reference value es. As a result, if eu> es, it is judged that the movable iron core has returned to normal, and nothing is output. If eu ≤ es, it is judged that the movable iron core has not returned and an abnormality detection signal is output. Is output. After that, the hold value eu is reset by waiting for the check command to disappear, and the presence or absence of the ON command is checked again.
When there is a command, the switch 27 is turned on and the process returns to the first step.

Next, the case of correcting the reference value es will be described. In that case, the microcomputer 40 uses the resistors R1 and R2.
The divided voltage e0 due to is taken in as information of the power supply voltage E0, and a current of a low output level such that the movable core does not move even when the solenoid is not excited is passed through the coil 11 and the average supply voltage (obtained from e0) at that time is obtained. The coil resistance can be calculated from the average detection current (obtained from e1) and the reference value es can be corrected accordingly to improve the detection accuracy.

For example, the switch 27 is ON / OFF-controlled by a signal whose PWM ON rate is fixed at about 1% at a frequency much higher than the ON signal at the time of checking, and the signal is turned OFF.
In the F state, if the power supply voltage is constant, the current value flowing in the OFF state changes due to the coil resistance, and the detection voltage e1 at that time changes. Thereby, the fluctuation of the coil resistance value can be detected. It is of course possible to use a temperature measuring element or the like. Further, instead of the microcomputer 40 of this embodiment, a wired logic circuit with digital elements can be used.

FIG. 7 shows a fourth embodiment of the present invention.
2 is a block diagram similar to that of FIG. 1, and parts corresponding to those in FIG. In this embodiment, after the solenoid is turned off, the movable iron core position is automatically and periodically checked with a predetermined time width, and the result is output as an analog amount.

In FIG. 7, the difference from the first embodiment of FIG. 1 is that a gate generator 29 is replaced by a pulse generator (PG) 41 for generating a check command pulse, and a check command is input from the outside. And the determination section 32
Instead, a movable iron core position calculation unit 42 is provided to output movable iron core position information by an analog signal.

According to the fourth embodiment, when the ON command is no longer input, the switch control unit 26 turns off the switch 27 to cut off the power supply from the power source 16 to the coil 11 of the solenoid and, at the same time, to the inverter 33. The output activates the timer 28. Timer 28 has set time TM
When 1 has elapsed, the pulse generator 41 is activated. The pulse generator 41 has a pulse width of TM2 as shown in FIG.
Then, a check command pulse P4 having a cycle of TM20 is generated.

At the rising edge of this check command pulse P4,
At the same time that the hold circuit 31 is set to start capturing data, the pulse generator 30 is activated. As a result, the pulse generator 30 generates an ON signal P1 having a pulse width of TM3 and a cycle of TM20, and the switch control unit 26
Turns on the switch 27 only during the period TM3 to excite the solenoid. The hold circuit 31 holds the detected voltage e ₁ immediately before the switch 27 is turned off, and the hold value eu is used as the movable core position calculating unit 4
2, the movable iron core position information ea is calculated and output.

At the fall of the check command pulse P4 from the pulse generator 41, the hold circuit 31 is reset and one check is completed, but the pulse generator 41 periodically outputs the check command pulse P4 at the cycle TM20. Since this occurs, the next check is immediately performed again, and the movable iron core position information ea is periodically output.

FIG. 8 shows the fifth embodiment of the present invention.
2 is a block diagram similar to that of FIG. 1, and parts corresponding to those in FIGS. 1 and 7 are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, a main switch 43 for turning on / off a solenoid and an exciting switch (normally open switch) 27 'for checking are separately provided in parallel so that they can be used in a conventional simple system. ..

The fifth embodiment differs from the fourth embodiment in FIG. 7 in that, in addition to the above points, the switch controller 26 is not necessary and the power supply voltage supplied to the coil 11 is converted into an inverter. 44 is used as a start signal for the timer 28, and the movable core position calculating section 42 is replaced by a determining section 32, an inverter 35, and an AND circuit 36 as in the first embodiment. ..

According to the fifth embodiment, it is turned on from the outside.
No command or check command is required, and the main switch 4
When 3 is turned on, the coil 11 is energized to operate the solenoid, and when turned off, the timer 28 is started, and after a predetermined time TM1, a period is periodically repeated at a predetermined cycle (same as TM20 of the fourth embodiment). Only for TM3, the switch 27 'is turned on to instantly energize the coil 11. Then, the amount of change in the current waveform at that time is detected by the hold value by the hold circuit 31, and the determination unit 32 determines the position of the movable iron core. As a result, if there is an abnormality in the position of the movable iron core,
An abnormality detection signal is output from the AND circuit 36.

FIG. 9 is a block diagram showing the sixth embodiment of the present invention. The parts corresponding to those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The sixth embodiment differs from the first embodiment shown in FIG. 1 in that a pulse generator (PG) 45 for generating a detection pulse having a pulse width TM4, an inverter 46 for inverting its output and an output thereof are provided. A hold circuit 47 to be a hold signal and two hold circuits 3
The point is that a differential amplifier 48 for calculating the difference between the hold values of 1 and 47 is provided.

This embodiment is an example in which the movable iron core position is checked using the falling waveform of the coil current immediately after the solenoid is excited for a short time. Figure 1 shows the check method.
Describing with reference to the time chart of 0, the ON instruction disappears and the switch control unit 26 turns OFF the switch 27.
After that, when the check command is input after the set time TM1 of the timer 28 has elapsed, the pulse generator 30 generates an ON signal having a pulse width TM3, and the switch control circuit 26
Activates the switch 27 for that period to excite the solenoid.

Therefore, the waveform of the output voltage e1 of the amplifier 18 corresponding to the waveform of the current flowing through the coil 11 is as shown in FIG. Then, at the fall of the ON signal, the hold circuit 31 shows the peak value of the voltage e1 in the same figure (b).
Hold and set to eu as shown in. Further, the pulse generator 45 generates a detection pulse having a pulse width TM4 from that point, and at the time of its fall, the hold circuit 47 holds the falling voltage e1 as shown in (c) of FIG.
Let d.

Then, the differential amplifier 48 outputs a signal ec shown in (d) of the same figure at a level corresponding to the difference between the hold voltages eu and ed of the hold circuits 31 and 47, and the discriminating section 32 uses it as a reference. Compared with the value es, if ec> es, a high level signal is output as shown in FIG. This is an OK signal indicating that the movable iron core has returned to normal.

If the movable iron core of the solenoid stays in the attracting position or is stopped during the return, the hold voltage ed does not decrease so much and the signal ec becomes small, so that ec> es does not hold. The output signal of the determination unit 32 becomes low level. This is an NG signal indicating that the movable core has not returned to normal. This example
It is suitable when there is little fluctuation in coil resistance or power supply voltage. Also in this case, the accuracy can be improved by correcting the reference value es as in the second embodiment shown in FIG.

FIG. 11 is a block diagram showing the seventh embodiment of the present invention. The parts corresponding to those in FIG. 9 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the check command is turned on through the normally closed switch 51, and the solenoid is turned on as shown in (b) of FIG.
After that, when the output voltage e1 of the amplifier 18 rises to the reference value es1 as shown in (a) of the figure, the normally closed switch 51 is turned off by the output of the comparator 50,
At the same time when the solenoid is turned off, the hold circuit 31
To hold the input voltage e1 = es1 at that time.

At the same time, the timer 52 is activated to generate a pulse after the set time TM5 and to hold the hold circuit 47.
Hold the voltage e1 during the fall to ed. Then, the differential amplifier 48 outputs a signal ec corresponding to the difference between the voltages es1 and ed, and the discriminator 32 uses it as the reference value es2.
The position of the movable iron core is determined by comparing with
If es2, a high level signal indicating normal is output.

According to this embodiment, the checking accuracy is improved as compared with the case of the sixth embodiment of FIG. Reference value es1 and es2
If the correction is added to, the accuracy can be further improved. Although the description of each of the above embodiments is based on detecting the change in the magnitude of the current value within a unit time, the slope of the falling or rising waveform is detected as in the eighth embodiment shown in FIG. It may be measured.

The checking method according to the eighth embodiment shown in FIG. 13 will be described with reference to the waveform chart of FIG. After turning on the switch 27 by the check command, the amplifier 18
When the output voltage e1 of 1 rises to the reference value es1, the normally closed switch 51 is turned off by the output of the comparator 50 and the switch 27 is shut off, as in the case of the seventh embodiment (FIG. 11).

In the eighth embodiment, the signal e1 'obtained by inverting the output voltage e1 of the amplifier 18 by the inverting circuit 53 is always differentiated by the differentiating circuit 54, and the differentiated waveform signal ey.
The peak value of is held by the peak hold circuit 55 as shown in FIG. The hold value ez is compared with the reference value es2 by the discriminating unit 32, and if ez> es2, a high level OK signal indicating that the movable iron core is normally returned is output.

That is, when the movable iron core of the solenoid is restored, the inductance of the coil 11 becomes small, so that the coil current falls quickly when the coil is energized for a short period of time to be cut off, and the slope of the waveform becomes steep. Signal e1 '
The peak of the differential waveform of becomes high. Therefore, the hold value ez also becomes large, so that ez> es2.

If the movable iron core of the solenoid is not restored, the inductance of the coil 11 is large, so that the fall of the coil current is slow and the slope of the waveform becomes gentle, contrary to the above case, so that the differential waveform of the signal e2 ' The peak becomes lower. Therefore, the hold value ez also becomes small, and ez> es2 does not hold.

Although the present embodiment is a detection method for checking when the switch 27 is turned off again, the rising slope of the current response waveform may be checked immediately after the excitation as in the seventh embodiment. FIG. 15 is a circuit diagram showing only the vicinity of the energizing portion to the coil 11 of the ninth embodiment of the present invention.

In this embodiment, the switch 27 is normally turned on.
In the example of when it is desired to accelerate demagnetization of the solenoid when the power is turned off, the changeover switch 57 is normally switched to the varistor 56 side as shown in the figure, and when the ON command is normally turned on / off, the varistor 56 is used. Promptly demagnetize and switch 27 to NO / OF by the check command.
The changeover switch 57 is changed over to the diode 25 side only when the switch F is turned on. Other configurations and operations may be the same as those in the above-described respective embodiments, and thus the description thereof will be omitted.

[0061]

As described above, according to the present invention, the effects listed below can be obtained. (1) If the check command is given after demagnetizing the solenoid, the position information of the movable iron core can be obtained at any time. (2) It can be composed of an electronic circuit, and there is no need to install any new components on the valve.

(3) If the check command is periodically issued based on the ON signal of the solenoid, the position information of the movable iron core can always be obtained. (4) If the current waveform during solenoid demagnetization is to be checked, it is checked during the period when the power supply is disconnected, so it is not affected by the ripple of the power supply. Therefore, a simple full-wave rectification power source can be used as it is, and a filter or the like is unnecessary.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a solenoid movable iron core position check device according to a first embodiment of the present invention.

FIG. 2 is a time chart similarly for explaining the operation.

FIG. 3 is a waveform diagram showing a difference in current response waveform depending on the position of the movable core and a diagram showing a relationship between the position of the movable core and the inductance of the solenoid coil.

FIG. 4 is a block diagram similar to FIG. 1 showing a second embodiment of the present invention.

FIG. 5 is a block diagram of an apparatus using a microcomputer showing a third embodiment of the present invention.

FIG. 6 is a flowchart of processing by the same microcomputer.

FIG. 7 is a block diagram similar to FIG. 1, showing a fourth embodiment of the present invention.

FIG. 8 is a block diagram similar to FIG. 7, showing a fifth embodiment of the present invention.

FIG. 9 is a block diagram similar to FIG. 1 showing a sixth embodiment of the present invention.

FIG. 10 is a time chart for explaining the operation of the same.

FIG. 11 is a block diagram similar to FIG. 9 showing a seventh embodiment of the present invention.

FIG. 12 is a waveform diagram for explaining the operation of the same.

FIG. 13 is a block diagram showing the eighth embodiment of the present invention.

FIG. 14 is a waveform diagram similarly provided for explaining the operation.

FIG. 15 is a circuit diagram showing only the vicinity of a current-carrying portion to a coil of a ninth embodiment of the present invention.

FIG. 16 is a vertical sectional view showing an example of a solenoid valve using a solenoid.

FIG. 17 is a diagram for similarly explaining the operation.

FIG. 18 is a block diagram showing an example of a conventional device for checking the operation of a solenoid.

FIG. 19 is also a time chart for explaining the operation.

[Explanation of symbols]

10 Solenoid 11 Coil 12
Movable iron core 13 Push rod 14 Fixed iron core 15
Current detection resistor 16 DC power supply 18 Amplifier 25
Diode 26 Switch control unit 27 Switch 27 '
Excitation switch 28,52 Timer 29 Gate circuit 30,41,45 Pulse generator 1,37,38,47 Hold circuit 32 Discrimination unit 36 AND circuit 39
Correction circuit 40 One-chip microcomputer 42
Movable iron core position calculator 43 Main switch 48 Differential amplifier 50
Comparator 51 Normally closed switch 53 Inversion circuit 54
Differentiation circuit 55 Peak hold circuit 56
Varistor 57 Changeover switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyuki Kihara 2-16-46 Minami Kamata, Ota-ku, Tokyo Within Tokimec Co., Ltd. (72) Kosuke Hatanaka Nakamura 2-chome 46-46, Minami Kamata, Tokyo In Tokimec Co., Ltd. (72) Inventor Akio Mito 2-16-46 Minami Kamata, Ota-ku, Tokyo In Tokimec Co., Ltd.

Claims (4)

[Claims] 1. A current detecting resistor is connected in series to a coil of a solenoid, and the coil is energized and excited for a short time width such that the movable iron core hardly moves, and is detected by the current detecting resistor. A method for checking the position of a movable core of a solenoid, characterized in that the position of the movable core is determined by detecting the amount of change in the response waveform of the current flowing through the coil. 2. A method for checking a movable iron core position of a solenoid according to claim 1, wherein the change amount of the response waveform of the current flowing through the coil is detected by a waveform change rate, that is, a differential value of the change amount per unit time. Characteristic Solenoid movable iron core position check method. 3. The method for checking the movable iron core position of a solenoid according to claim 1, wherein the change amount of the response waveform of the current flowing through the coil is performed at the time of rising due to excitation. 4. The change amount of the response waveform of the current flowing through the coil is performed at the falling edge after excitation.
Alternatively, the method of checking the movable iron core position of the solenoid according to the item 2.