JPH0350225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting an abnormality in a DC solenoid device for an electromagnetic valve driven by a DC excitation current.

In AC solenoid devices driven by AC excitation current, when an abnormality occurs, the excitation current becomes excessive, so it is necessary to detect whether or not an abnormality has occurred by detecting the magnitude of the excitation current. It can be done easily. In contrast, with DC solenoid devices, the magnitude of the excitation current does not change even if an abnormality occurs, so conventionally the only way to check whether the solenoid is energized is to detect the voltage across both ends of the solenoid. Not known.

An object of the present invention is to provide a device for detecting whether a DC solenoid device for an electromagnetic valve is in an abnormal state.

The present invention provides a plunger 3 for driving an electromagnetic valve.
In an abnormality detection device for a DC solenoid device for an electromagnetic valve, which is driven by applying DC power to the solenoid 2 and energizing it, a closed loop is formed by the solenoid 2, a switch 4, and a DC power supply 5, and in this closed loop, A current transformer 6 is provided, a first peak hold circuit 7 is provided with the output of the current transformer 6, and a first peak hold circuit 7 is provided with the output of the first peak hold circuit 7, which detects and holds the local maximum value.
A first pulse generation circuit 1 that derives a pulse when the first peak hold circuit 7 detects a local maximum value.
1, a flip-flop 12 which is set by the pulse from the first pulse generating circuit 11, an inverting circuit 13 which inverts the output of the current transformer 6, and an output of the inverting circuit 13, which detects the maximum value. When the output of the second peak hold circuit 14 is given and the second peak hold circuit 14 detects a maximum value, a second peak hold circuit 14 is provided to derive a pulse and reset the flip-flop 12. 2 pulse generation circuit 16
and a local maximum value iP of the excitation current of the solenoid 2 detected by either one of the first and second peak hold circuits 7, 14, and a local minimum value iP detected by the other one. The value iQ is compared with each predetermined value stored in the memory 19, and the set or reset time of the flip-flop 12 corresponding to the time Δt from the maximum value iP of the excitation current to the minimum value iQ of the flip-flop 12 is determined. This is an abnormality detection device for a direct current solenoid device for an electromagnetic valve, characterized in that it includes a processing device 10 that compares the value with a predetermined value stored in a memory 19 and detects an abnormality based on the results of these comparisons. .

FIG. 1 is a block diagram of one embodiment of the present invention. The DC solenoid device 1 for an electromagnetic valve includes a solenoid 2, a plunger 3 that is displaced by the electromagnetic force of the solenoid 2, and a spring 20 that biases the plunger 3. The solenoid 2 is driven by DC power from a DC power supply 5 via a switch 4.

According to experiments conducted by the inventor of the present invention, it was found that the excitation current flowing through the solenoid 2 changes over time immediately after the switch 4 is turned on as shown in FIG. When the plunger 3 is displaced with a normal stroke by the excitation of the solenoid 2, the time course of points O, P, Q, and R is followed as shown by a curve 11. An abnormality occurred in the DC solenoid device 1, and the plunger 3
is not displaced at all, that is, the stroke is zero, as shown by curve l4, O, P, R
, and no local maximum or minimum values are formed at this time. When the stroke of the plunger 3 is suppressed to be shorter than when it is normal, the exciting current follows the time course of O, P, Q1, and R as shown by the curve 12. In an abnormal situation where the stroke of the plunger 3 is further restricted, curve l3
The time course of the excitation currents O, P, Q2, and R is traced as shown in FIG. In other words, the exciting current at time tP when plunger 3 reaches its stroke end
iP, the time tQ at which the repulsive force returns after reaching the stroke end, and the excitation current iQ at that time.
By focusing only on this, it is possible to determine whether the stroke of the plunger 3 is normal or abnormal. According to the present invention, when the DC solenoid device 1 is normal, the local maximum value iP, the local minimum value iQ of the exciting current, and the time tP of points P and Q,
Measure the time Δt between tQ in advance and use these values.
An abnormality is detected by comparing iP, iQ, and Δt each time the solenoid 2 is excited.

Referring again to FIG. 1, the exciting current flowing through the solenoid 2 is detected by the current transformer 6. The output from current transformer 6 is given to peak hold circuit 7. FIG. 3 shows the time course of the excitation current immediately after the switch 4 is turned on. The time variation of the excitation current shown in FIG. 31 is the same as the characteristic described in connection with FIG. 2. The output from the peak hold circuit 7 is shown in FIG. This local maximum value iP is input to the processing device 10 via the analog-to-digital converter 9. The output from peak hold circuit 7 via line 8 is also provided to pulse generation circuit 11. As a result, the pulse generating circuit 11 generates the pulse shown in FIG. 3 to set the flip-flop 12 at time tP when the maximum value of the excitation current occurs. The output from current transformer 6 is inverted by inverting circuit 13 and input to peak hold circuit 14 . The output from the inverting circuit 13 is shown in FIG.
This waveform is an inversion of the waveform shown in FIG. 3 described above. The peak hold circuit 14 derives a signal having a waveform shown in FIG. The pulse generating circuit 16 detects this minimum value.
At time tQ when iQ occurs, the pulse shown in FIG. 3 is derived to reset flip-flop 12. The output from the peak hold circuit 14 via line 15 is connected to an analog-to-digital converter 17
is inputted to the processing device 10 via. The set output of the flip-flop 12 becomes high level at the time Δt from point P to point Q, as shown in FIG. 3. This time Δt is measured by a signal from the oscillation circuit 18 that is input to the processing device 10. In the memory 19 built into the processing device 10, the local maximum value iP, the local minimum value iQ, and the time Δt of the excitation current when the DC solenoid device 1 is normal are stored in advance. Each stored value is compared with the value each time the switch 4 is turned on. In this way, the display 2 detects whether or not the DC solenoid device 1 is abnormal.
Display on 1. Further, the dimensional accuracy of the DC solenoid device 1 can also be confirmed after the assembly is completed.

FIG. 4 is a sectional view for explaining the moving operation of the plunger 3. When the solenoid 2 is not energized, the lower part of the plunger 3 is in position Oa.
When the switch 4 is turned on and the solenoid 2 is energized, the plunger 3 is displaced downward against the spring force of the spring 20 as shown in FIG. The excitation current iP flows at this time, and the time is tP, which corresponds to point P in FIG. Thereafter, due to the spring force of the spring 20, the lower part of the plunger 3 reaches the position Qa, as shown in FIG. 42.
When the lower part of plunger 3 reaches position Qa,
The exciting current is iQ, and this time is tQ,
It corresponds to point Q. Note that before the solenoid 2 is energized, the lower part of the plunger 3 is at the position Oa as described above, and this state is as shown in FIG.

In the present invention, as described above, the local maximum value iP, the local minimum value
By comparing iQ and time Δt with predetermined values during normal operation, it is possible to reliably detect an abnormality in the DC solenoid device that drives the electromagnetic valve. In a DC solenoid device that drives such an electromagnetic valve, the stroke of the plunger 3 is relatively large, and it is necessary to detect whether the displacement amount has been reliably achieved. The inventor of the present invention has discovered that, as shown in FIG. 2, the excitation current flowing through the solenoid 2 goes from zero to a local maximum value iP and a local minimum value iQ in this order over time, and then further increases to a large value. We discovered the phenomenon of change, and based on this phenomenon, in the present invention,
It is important to compare the values of iP, iQ, and Δt with their normal values. If the configuration is such that only the time from time O to time tP is measured and compared with the normal value, when the plunger 3 moves at a low speed, the time from O to tP will be the same. Even if there is, the abnormality cannot be detected. Therefore, in the present invention, when the excitation current iP is detected and the plunger 3 moves at a low speed, the local maximum value iP is compared with the normal value, considering that the local maximum value iP changes small. .

Furthermore, in the present invention, when the stroke of the plunger 3 is smaller than normal, such as when the plunger 3 is caught in the middle of its movement, the speed of the plunger 3 is also small, and therefore the time Δt becomes small as described above. If the configuration is such that the time Δt is simply compared with the normal value, this time Δt
Even if the value is the same as the normal value, it cannot be determined whether the stroke of the plunger 3 is normal. In the present invention, since both the local maximum value iP and the time Δt are compared with respective predetermined values during normal operation, it is possible to reliably detect whether or not the DC solenoid device for an electromagnetic valve is abnormal.

Furthermore, in the present invention, the minimum value iQ of the excitation current is also compared with the normal value. The fact that the minimum value iQ is a normal value means that the plunger 3 moves over the entire stroke without getting caught midway, compresses the spring 20, and reaches the position Pa.
It means that the position Qa has been reached after that. In the present invention, since the local maximum value iP, time Δt, and local minimum value iQ are compared with each predetermined value during normal operation, it is possible to reliably detect abnormalities in the DC solenoid device for electromagnetic valves. The excellent effect of being able to do so is achieved.

Although in the embodiment described above, the current transformer 6 is interposed in the negative voltage line of the DC power supply 5 as shown in FIG. In this case, the maximum value iP is detected by the peak hold circuit 14, and another one is detected by the peak hold circuit 14.
The minimum value iQ is detected by two peak hold circuits 7, and the processing device 10 receives the digital value of the maximum value iP via the analog-to-digital converter 17, and also receives the digital value of the minimum value iQ via the analog-to-digital converter 9. receiving the value and comparing it with each predetermined value, and comparing the time from the reset state to the set state of the flip-flop 12 with a predetermined value corresponding to the time Δt;
It is also possible to detect abnormalities in the DC solenoid device for electromagnetic valves in this manner. In this way, even if the hardware has the same configuration and the converter 6 is installed on the negative voltage line of the DC power supply 5 or on the positive voltage line, it is possible to detect abnormalities. It is only necessary to change the respective predetermined values with which the digital values from the analog-to-digital converters 9, 17 in the processing device 10 are compared, making the invention extremely easy to use in connection with existing DC solenoid devices for electromagnetic valves. It is possible to implement it.

As described above, according to the present invention, it has been discovered that the initial change characteristics of the excitation current in a DC solenoid device are different between abnormal and normal times, and by focusing on this phenomenon, abnormalities in the DC solenoid device can be detected. Not only this, but also the dimensional accuracy can be confirmed after the assembly of the DC solenoid device is completed.

In particular, in the present invention, the maximum value iP and the minimum value of the excitation current are
Since a total of three elements, iQ and time Δt, are compared with each predetermined value during normal operation, it is possible to reliably detect abnormalities in DC solenoid devices used in electromagnetic valves with relatively large strokes. This excellent effect is achieved.

Furthermore, in the present invention, the current transformer 6 may be interposed in the negative voltage line of the DC power supply 5, or alternatively may be interposed in the positive voltage line, and in this case, the current transformer 6 may be provided in the first and second Since it is only necessary to change each predetermined value with which the outputs of the peak hold circuits 7 and 14 are to be compared, the present invention can be very easily implemented in conjunction with existing DC solenoid devices for electromagnetic valves.

Moreover, in the present invention, since the current transformer 6 is used, the electric power given to the solenoid 2 of the DC solenoid device does not change, and the DC current that drives the electromagnetic valve does not impair the characteristics of the electromagnetic valve. It is possible to reliably detect abnormalities in the solenoid device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a graph showing the initial current change characteristics of the excitation current according to the inventor's experiment, FIG. 3 is a waveform diagram explaining the operation of the block diagram in FIG. 1, and FIG. 4 is a graph for explaining the moving operation of the plunger 3. FIG. 1...DC solenoid device, 2...Solenoid, 3...Plunger, 4...Switch, 5...
DC power supply, 6...Current transformer, 7, 14...Peak hold circuit, 9, 17...Analog-to-digital converter, 10...Processing device, 11, 16...Pulse generation circuit, 12...Flip-flop, 13 ...Inverting circuit, 18...Oscillator, 19...Memory.

Claims (1)

[Claims] 1. In an abnormality detection device for a DC solenoid device for an electromagnetic valve, which drives a plunger 3 that drives an electromagnetic valve by applying DC power to a solenoid 2 and energizing it, the solenoid 2, the switch 4, and the DC a current transformer 6 provided in this closed loop; a first peak hold circuit 7 to which the output of the current transformer 6 is applied and which detects and holds the maximum value; The output of the peak hold circuit 7 is given,
A first pulse generation circuit 1 that derives a pulse when the first peak hold circuit 7 detects a local maximum value.
1, a flip-flop 12 which is set by a pulse from the first pulse generating circuit 11, an inverting circuit 13 which inverts the output of the current transformer 6, and an output of the inverting circuit 13, which detects the maximum value. When the output of the second peak hold circuit 14 is given and the second peak hold circuit 14 detects a local maximum value, a second peak hold circuit 14 is provided to derive a pulse and reset the flip-flop 12. 2 pulse generation circuit 16
and a local maximum value iP of the excitation current of the solenoid 2 detected by either one of the first and second peak hold circuits 7, 14, and a local minimum value iP detected by the other one. The value iQ is compared with each predetermined value stored in the memory 19, and the set or reset time of the flip-flop 12 corresponding to the time Δt from the maximum value iP of the excitation current to the minimum value iQ of the flip-flop 12 is determined. 1. An abnormality detection device for a DC solenoid device for an electromagnetic valve, characterized in that the abnormality detection device includes a processing device 10 that compares the value of the current value with a predetermined value stored in a memory 19, and detects an abnormality based on the results of these comparisons.