JP2995107B2 - How to check the position of the movable iron core of the solenoid - Google Patents

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 the position of a movable iron core 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 the body 1, and the spool 3 is moved to a right-hand 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 in accordance with the magnitude of the exciting current. Moves leftward due to the suction force between the fixed iron core 14 and the spool 3 by the push rod 13.
Is moved to the left to a position where communication is established between ports PA and TB.

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

Conventionally, as a method of checking the operation state of such a solenoid, for example, Japanese Patent Laid-Open No. 1-2655
As disclosed in Japanese Patent Application Laid-Open No. 04-204, there is known a method of detecting an operating state of a movable iron core from a difference in current response waveform depending on a moving state of the movable core when the solenoid is turned ON or OFF. The operation check when the solenoid is turned off by this method will be briefly described with reference to FIGS.

[0005] As shown in FIG.
When a current detection resistor 15 is connected in series to 1 and a current flows through the series circuit by turning on a switch 17 from a power supply 16, the magnitude of the exciting current flowing through the coil 11 is converted into a voltage by the resistor 15. The operation when the solenoid is ON can be checked by utilizing the fact that the response waveform differs depending on whether the movable iron core moves or not.

When the switch 17 is turned from ON to OFF (time t1 in FIG. 19), the energy stored in the coil 11 causes the polarity of the power supply voltage to be opposite to that of the power supply voltage as shown in FIG. Spike voltage occurs. This voltage is passed through a limiter 19 to remove the voltage below a predetermined level, and the amplifier 1
When the signal is amplified at 8, a constant negative voltage is output until time t2, as shown in FIG.

[0007] When the movable core starts to return at time t2, the impedance of the coil 11 changes, thereby delaying the convergence of the spike voltage. And at time t3
When the return of the movable iron core is completed, the impedance change disappears, and the spike voltage rapidly converges to zero. Therefore, the differentiated 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 has been normally turned off.

This signal is ANDed with the output from the inverter 22 shown in (e) of FIG. 1 by the AND circuit 23 and output as a solenoid OFF detection signal. As described above, many other devices that determine whether the movable iron core of the solenoid moves or not based on a difference in response waveform of current or voltage are disclosed. As other methods of checking the movable iron core position of the solenoid, many methods have been proposed in which a mechanical limit switch is built in the solenoid, or a non-contact type proximity switch or a potentiometer is built in and the detection is performed using a detection signal. I have.

[0009]

However, in such a conventional method of checking the position of the movable iron core of the solenoid, in the former method, attention is paid to the current discharge waveform when the solenoid is turned off, and it is determined whether the movable iron core is moving or not. The solenoid is turned off to determine whether or not the armature has returned from the difference in the discharge waveform depending on whether
You can only judge the moment you set F.

For this reason, it is necessary to re-energize and turn OFF again in order to confirm whether or not this has been caused by noise. However, this would not be possible because the spool or actuator would be moved, and this would not be possible. Sex was low. In the case of a so-called shockless solenoid valve in which the movable iron core is hardly moved by oil immersion, the movement of the movable iron core is so slow that a large difference in response waveform does not appear.

Although the latter has certainty, the mechanical structure is generally complicated, and extra space is required for storing the switches and the like, and the mechanical one has a problem in durability. Was.

The present invention has been made in view of such a conventional problem, and after turning off a solenoid,
It is an object of the present invention to check the position of the movable iron core at any time as needed, to provide a highly reliable check result, and to eliminate the need to incorporate a mechanical switch or the like in the solenoid.

[0013]

According to the present invention, in order to achieve the above object, a current detecting resistor is provided in series with a coil of a solenoid, and the current detecting resistor is provided only in a short time width such that the movable core hardly moves. The present invention provides a method for checking the position of a movable iron core of a solenoid, which detects the position of a movable iron core by energizing and exciting the coil and detecting a change amount of a response waveform of a current flowing through the coil detected by the current detecting resistor. I do.

The amount of change in the response waveform of the current flowing through the coil may be detected based on 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 due to excitation or at the time of falling after excitation.

[0015]

According to the present invention, after the solenoid is turned off, excitation is performed for a time width in which the movable iron core of the solenoid hardly moves, and the difference in response current waveform due to the difference in inductance of the solenoid depending on the position of the movable iron core is obtained. It can be determined whether the movable iron 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 (the operation is generally completed within 0.1 second), the check can be performed any number of times at any time, so that the reliability is high and the monitoring from the controller side is easy. is there. In addition, since there is no need to incorporate a mechanical switch or the like in the solenoid, there is no space problem or durability problem.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram of a movable iron core position checking device for a solenoid according to a first embodiment of the present invention, and portions corresponding to those in FIG. 18 are denoted by the same reference numerals. First, the configuration will be described. A current detecting resistor 15 is connected in series to a solenoid coil 11, and a diode 25 is connected in parallel to the series circuit.
6 through a switch 27 so that a series circuit of the coil 11 and the resistor 15 can be energized.

At this time, the diode 25 is reverse-biased and thus is non-conductive. However, when the switch 27 is turned off, a current caused by the energy stored 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 in accordance with 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 the output thereof, a gate circuit 29 for receiving a check command P4 after the timer set time, and a pulse generator 3 for generating an ON signal P1 by the check command P4 passed through the gate circuit 29
0 is provided.

Further, an amplifier 18 for amplifying the terminal voltage e of the resistor 15 that occurs in accordance with the magnitude of the exciting current flowing through the coil 11, a hold circuit 31 for holding the output voltage e ₁ at the fall of the ON signal P1 Inverter 34,
A discriminator 32 for comparing the hold output eu of the hold circuit 31 with a reference value es and outputting a discrimination signal P3 ', an inverter 35 for inverting the discrimination signal P3', and an output signal P3, a check command P4 and an inverter 34 And an AND circuit 36 for ANDing 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 adsorption position adsorbed to the fixed iron core 14 due to the demagnetization. A method for checking the position of the movable iron core of the solenoid according to this embodiment will be described with reference to the time chart of FIG.

First, when the ON command for operating the solenoid is set to "L" as shown in FIG. 2A at a time point a in FIG. 2, the switch control unit 26 to which the command is inputted turns the switch 27 ON.
The current is cut off from the DC power supply 16 to the coil 11 by the FF, but the current accumulated in the coil 11 and the resistor 15 through the diode 25 continues for a short time due to the energy stored in the coil 11, and then completely demagnetized. Is 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 starts the timer 28. 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 of the predetermined time width TM2 shown in FIG.
The pulse generator 30 is activated at the rising time point b, and generates an ON signal P1 having a pulse width TM3 as shown in FIG. The switch control unit 26 turns on the switch 27 only during the period when the ON signal P1 is "H", and the DC power supply 1
From 6 the coil 11 is energized to excite the solenoid for a short time.

Therefore, the pulse width T of the ON signal P1
M3 is set to a short time width such that the movable iron core hardly moves even when the solenoid is energized by energizing the coil 11. 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. At the time point b of the rise of the check command P4, the hold circuit 3
Set "1" to start data capture.

At the falling point c of the ON signal P1, the output of the inverter 34 becomes "H" as shown in FIG.
Hold 1 Therefore, the hold circuit 31
Of 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 during the period TM3 at the time of the rise, and the inductance L of the coil 11 will be described later.
Is smaller, and the inductance L changes in accordance with the position of the movable core. Therefore, the hold value eu indicates the position information of the movable core.

Therefore, the hold value eu is determined by the determination unit 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 it is, 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 output P3 shown in FIG. 2A obtained by inverting the discrimination output P3 'by the inverter 35, the check command P4 and the output signal P2 of the inverter 34 are ANDed by the AND circuit 36. Then, an abnormality detection signal shown in FIG. Therefore,
If the movable core returns to the normal state and is at the initial position as shown on the normal side in FIG. 2, no abnormality detection signal is output (low level) as shown on the normal side in FIG. As shown on the abnormal side of the figure, if the movable iron core does not return to normal and remains at the suction position, a pulse-like abnormality detection signal (high level) is output.

Thereafter, when the check command is turned off at the time point d, the hold circuit 31 is reset, eu becomes 0, the abnormality detection signal is not output, and the next check command is waited. Thereafter, when a check command is input again, the solenoid is again excited 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 position of the movable iron core 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. The detection voltage e1 is monitored, and it is set to a preset value (zero level).
The timer 28 may be activated when it has dropped to the minimum. When the inductance L of the coil 11 is large or the like, it is more reliable to start the timer based on the actual current as described above than to set the time TM1 from the time when the current is cut off. In that case, the timer set time TM1 may be zero.

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 is opposed to the spring force of the spring 6 + fluid force. It moves while pressing 3 and the like, and is attracted to the fixed iron core 14. However, even if the current is applied to the coil 11 for a very short time and the coil is excited, the solenoid output does not exceed the spring force + fluid force. The movable iron core does not move.

Alternatively, even if it is slightly moved in the suction direction for a moment, as long as there is no problem in the whole system, it is acceptable. Therefore, the pulse width TM of the ON signal is set to fall within this range.
It is necessary to set 3. (A) and (b) in FIG.
FIG. 11 is a waveform diagram showing a difference in a current response flowing through the coil 11 due to excitation of the pulse width TM3, that is, a voltage response waveform detected by the resistor 15 depending on the position of the movable core.

The inductance L of the coil 11 is smallest when the movable core is at the initial position (the position farthest from the fixed core), and is largest when the movable core is at the suction position (position closely contacted with the fixed core). It changes depending on the position of the movable iron core as shown in FIG. The amount of change (rise) of the voltage waveform at the time of excitation due to this inductance L
Since the inductance is small when the movable core is at the initial position, it rises greatly as shown in FIG. 3A, and when it is at the suction position, the inductance is large and the amount of rise is small.

Therefore, the voltage e corresponding to this amount of change
By detecting u and comparing it with the reference value es, it is possible to determine where the movable iron core is.
Although the example of the binary determination has been described, if this value eu is compared with a plurality of reference values having different levels, the position of the movable iron core in a plurality of stages can be detected, and the resolution of the position detection is improved. And the accuracy is improved, and the degree of abnormality or normality can be detected. If this 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 a 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 additionally provided to the check device shown in FIG. This is to correct the reference value es in response to a 100% change in the current value due to a rise in coil temperature or a change in the power supply voltage, thereby obtaining a correct detection point.

The hold circuit 37 is set at the rise 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 rise of the ON command,
From the inverter 33 as input data, and when the ON command becomes "L", the value is held by the rise of the output of the inverter 33, and the hold value eu0 (coil in a steady state when the solenoid is operated) 11 (a voltage corresponding to the value of the current flowing through 11) to the correction circuit 39.

The correction circuit 39 applies 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 determination unit 32. The response characteristic of the current flowing through the coil 11 when the switch 27 is turned on is given by the following equation (Equation 1).
Is represented by

[0038]

(Equation 1)

R: the internal resistance of the coil 11 + the resistance value of the resistor 15 L: the inductance of the coil 11 Therefore, the power supply voltage E 0 immediately before the interruption of the coil current
Then, by holding the voltage eu0 corresponding to the steady-state current I at that time, the value of R is known by R = E0 / I, and the reference value es can be corrected according to the fluctuation. By this correction, the accuracy of the determination of the movable iron core position by the determination unit 32 can be increased.

In each of the above-described embodiments, the case where the position of the movable iron core is checked by instantaneously exciting the solenoid in a completely demagnetized state is described. It is of course possible to excite from the state in which the current is flowing so that a current of 100% flows. 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 diagram of a third embodiment using a one-chip microcomputer (hereinafter abbreviated as "microcomputer"). Parts corresponding to those in FIG. 1 are denoted by the same reference numerals. Their description is 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 a switch (SW) 27, and outputs an output voltage e1 (a voltage corresponding to a current value flowing through the coil 11) of the amplifier 18 to an internal circuit. The A / D converter converts the digital value into a digital value and checks the digital value. 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, no interlock means is required between them.

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

Next, processing by the microcomputer 40 will be described with reference to FIG. This is a process when the reference value es is not corrected. When this routine starts,
It checks whether there is an ON command, and if there is (if "H"), then checks whether the switch 27 is ON or not.
If so, the process returns to the beginning, 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 check, after the switch 27 is turned off, a set time (for example, 100 μS) which is longer than the time required for the solenoid to be turned off (return of the movable iron core) has elapsed. Waits for the input of a check command. O before input of check command
When the N command is received, the switch 27 is turned on again to energize the coil 11. When a check command is input after the elapse of 100 μS, an ON pulse having a predetermined short pulse width is generated, and the switch 27 is turned ON only during that time.

The A / D conversion value of the output voltage e1 from the amplifier 18 is held at the falling 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 determined that the movable iron core has returned to normal, and nothing is output. However, if eu ≦ es, it is determined that the movable iron core has not returned, and an abnormality detection signal is output. Is output. After that, it waits for the check command to disappear, resets the hold value eu, checks again for the presence of the ON command, and waits for the next check command if there is no ON command.
When a command is issued, the switch 27 is turned on and the process returns to the first step.

Next, a case where the reference value es is corrected will be described. In that case, the microcomputer 40 determines that the resistors R1 and R2
Is obtained as information of the power supply voltage E0, a current having a low output level such that the movable iron core does not move even when the solenoid is not excited is supplied to the coil 11, and the average supply voltage (obtained from e0) at that time is obtained. The coil resistance is calculated based on the average detection current (obtained from e1), and the reference value es or the like is corrected in accordance therewith, thereby increasing the detection accuracy.

For example, the switch 27 is turned on / off by a signal having a frequency much higher than the ON signal at the time of the check and the PWM ON rate fixed at about 1%, and the signal is turned off.
In the F state, if the power supply voltage is constant, the value of the current flowing in the OFF state changes due to the coil resistance, and the detection voltage e1 at that time changes. Thereby, a change in the coil resistance value can be detected. Of course, it is also possible to use a temperature measuring element or the like. Further, instead of the microcomputer 40 of this embodiment, a wired logic circuit using 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 portions corresponding to FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In this embodiment, after the solenoid is turned off, the position of the movable iron core is automatically and periodically checked with a predetermined time width, and the result is output as an analog amount.

7 differs from the first embodiment shown in FIG. 1 in that a pulse generator (PG) 41 for generating a check command pulse is provided instead of the gate circuit 29, and a check command is inputted from outside. And the discrimination unit 32
The only difference is that a movable core position calculating unit 42 is provided in place of and the movable core position information is output by an analog signal.

According to the fourth embodiment, when the ON command is no longer input, the switch control section 26 turns off the switch 27 to cut off the power supply from the power supply 16 to the coil 11 of the solenoid. The timer 28 is started by the output. Timer 28 is set time TM
At the elapse of 1, the pulse generator 41 is activated. The pulse generator 41 has a pulse width of TM2 as shown in FIG.
Generates a check command pulse P4 having a cycle of TM20.

At the rise of the check command pulse P4,
At the same time as setting the hold circuit 31 to start taking in data, the pulse generator 30 is started. As a result, the pulse generator 30 generates an ON signal P1 having a pulse width of TM3 and a cycle of TM20.
Turns on the switch 27 only during the period TM3 to excite the solenoid. Then, the detection voltage e ₁ immediately before the switch 27 is turned off is held by the hold circuit 31, and the hold value eu is used as the movable core position calculation unit 4.
2 to calculate and output the movable core position information ea.

At the falling of the check command pulse P4 from the pulse generator 41, the hold circuit 31 is reset and one check is completed. However, the pulse generator 41 periodically outputs the check command pulse P4 at a period TM20. Then, the next check is immediately performed again, and the movable core position information ea is periodically output.

FIG. 8 shows a fifth embodiment of the present invention.
10 is the same block configuration diagram as that of FIG. 1, and the portions corresponding to FIG. 1 and FIG. 7 are denoted by the same reference numerals, and description thereof is omitted. In this embodiment, a main switch 43 for turning ON / OFF the solenoid and an excitation 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 shown in FIG. 7 in that, in addition to the above-described points, the switch control unit 26 is not required, and the power supply voltage supplied to the coil 11 is changed by the inverter. The difference is that the start signal of the timer 28 is set via the switch 44 and that the discriminating unit 32, the inverter 35, and the AND circuit 36 are provided instead of the movable core position calculating unit 42 as in the first embodiment. .

According to the fifth embodiment, external ON
Commands and check commands are not required, and the main switch 4
When the switch 3 is turned on, the coil 11 is energized to operate the solenoid, and when the switch 3 is turned off, the timer 28 is started, and a predetermined period (same as TM20 of the fourth embodiment) is periodically applied after a predetermined time TM1. The switch 27 'is turned ON only for TM3, and the coil 11 is instantaneously energized. Then, the amount of change in the current waveform at that time is detected by the hold value of the hold circuit 31, and the determination unit 32 determines the position of the movable iron core. As a result, if the position of the movable iron core is abnormal,
An abnormality detection signal is output from the AND circuit.

FIG. 9 is a block diagram showing a sixth embodiment of the present invention. Parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and their description is omitted. The sixth embodiment differs from the first embodiment 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 the output thereof, and an output thereof are provided. A hold circuit 47 serving as a hold signal and two hold circuits 3
The difference 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 position of the movable iron core 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
Referring to the time chart of FIG. 0, the ON command disappears and the switch control unit 26 turns off the switch 27.
After that, when a check command is input after the set time TM1 of the timer 28 has elapsed, the pulse generator 30 generates an ON signal of the pulse width TM3, and the switch control circuit 26
Turns on 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, when the ON signal falls, the hold circuit 31 changes the peak value of the voltage e1 to the value shown in FIG.
And hold it as eu. Further, the pulse generator 45 generates a detection pulse having a pulse width TM4 from that point in time, and at the time of its fall, the hold circuit 47 holds the falling voltage e1 as shown in FIG.
d.

Then, the differential amplifier 48 outputs a signal ec shown in (d) of FIG. 4 at a level corresponding to the difference between the hold voltages eu and ed of the two hold circuits 31 and 47, and the discriminator 32 uses this as a reference. Compared to 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 remains at the suction position or stops during return, the hold voltage ed does not decrease so much and the signal ec decreases, so that ec> es does not hold. The output signal of the discriminating unit 32 becomes low level. This is an NG signal indicating that the movable iron core has not returned to normal. This example is
It is suitable when there is little variation in coil resistance, power supply voltage, etc. In this case, the accuracy can be improved by adding a correction to the reference value es as in the second embodiment shown in FIG.

FIG. 11 is a block diagram showing a seventh embodiment of the present invention. In FIG. 11, parts corresponding to those in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, the check command is set to an ON signal via the normally closed switch 51, and the solenoid is turned ON as shown in FIG.
After that, when the output voltage e1 of the amplifier 18 rises to the reference value es1 as shown in FIG.
When the solenoid is turned off, the hold circuit 31
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 the hold circuit 47
Then, the voltage e1 in the middle of falling is held to be ed. Then, the differential amplifier 48 outputs a signal ec corresponding to the difference between the voltages es1 and ed, and the discriminating section 32 outputs the signal ec2 to the reference value es2.
, The position of the movable iron core is determined, and as a result, ec>
If it is es2, it outputs a high-level signal indicating that it is normal.

According to this embodiment, the checking accuracy is improved as compared with the sixth embodiment shown in FIG. Reference values es1 and es2
, The accuracy can be further improved. Although the description of each of the above embodiments is based on detecting a change in the magnitude of the current value within a unit time, the slope of the falling or rising waveform is changed 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 diagram of FIG. After the switch 27 is turned on by the check command, the amplifier 18
When the output voltage e1 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 cut off, as in the above-described seventh embodiment (FIG. 11).

In the eighth embodiment, a signal e1 'obtained by inverting the output voltage e1 of the amplifier 18 by an inverting circuit 53 is always differentiated by a differentiating circuit 54, and the differentiated waveform signal ey is obtained.
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 discriminator 32. If ez> es2, a high-level OK signal indicating that the movable iron core has returned to normal 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 time and cuts off, and the waveform has a steep slope. Signal e1 '
The peak of the differential waveform becomes higher. Therefore, the hold value ez also increases, so that ez> es2.

If the movable iron core of the solenoid has not returned, the inductance of the coil 11 is large, so that the falling 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 'is The peak becomes lower. Therefore, the hold value ez also becomes small, so that ez> es2 does not hold.

Although this 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 a portion where a coil 11 is energized according to a ninth embodiment of the present invention.

In this embodiment, the switch 27 is always ON.
In this example, it is desired to speed up the demagnetization of the solenoid when the solenoid is switched from OFF to OFF, and the changeover switch 57 is normally switched to the varistor 56 side as shown in the figure. To quickly demagnetize, and switch 27 is turned on / off by check command.
Only when F is performed, the changeover switch 57 is switched to the diode 25 side. Other configurations and operations may be the same as those in the above-described embodiments, and a description thereof will not be repeated.

[0061]

As described above, according to the present invention, the following effects can be obtained. (1) After demagnetizing the solenoid, if a check command is given, the position information of the movable core can be obtained at any time. (2) It can be configured with an electronic circuit, and no new parts are required to be attached to the valve.

(3) If the check command is issued periodically 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 at the time of solenoid demagnetization is to be checked, it is checked during the period of disconnection from the power supply, so it is not affected by the ripple of the power supply. Therefore, a simple power supply for full-wave rectification can be used as it is, and a filter or the like becomes unnecessary.

[Brief description of the drawings]

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

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

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 configuration diagram of an apparatus using a microcomputer according to a third embodiment of the present invention.

FIG. 6 is a flowchart of a process performed by the 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 embodiment.

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

FIG. 12 is a waveform chart for explaining the operation.

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

FIG. 14 is a waveform chart for explaining the operation of the same.

FIG. 15 is a circuit diagram showing only the vicinity of a portion where a coil is energized according to a ninth embodiment of the present invention.

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

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

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

FIG. 19 is a time chart for explaining the same 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 Discriminator 36 AND circuit 39
Correction circuit 40 One-chip microcomputer 42
Movable iron core position calculation section 43 Main switch 48 Differential amplifier 50
Comparator 51 Normally closed switch 53 Inverting circuit 54
Differentiating circuit 55 Peak hold circuit 56
Varistor 57 selector switch

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Kihara 2-16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Inc. (72) Inventor Kosuke Hatanaka 2--16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Co., Ltd. (72) Inventor Akio Mito 2-16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) H01F 7/18 H01F 7/16

Claims (4)

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