JP2954905B2 - Cylinder piston position detecting device and centralized control device therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston position detecting device for detecting the position of a piston of a cylinder such as a pneumatic cylinder or a hydraulic cylinder, and a centralized control device for centrally controlling the detecting device.

[0002]

2. Description of the Related Art Conventionally, a magnetic sensor used in this type of piston position detecting device includes a magnetoresistive element which generates an output having a magnitude corresponding to a distance from a magnet provided on a piston, and a threshold value separately provided. It comprises two different comparators and two illuminants which emit green and red light respectively according to the output of each comparator. When the piston is in a certain optimum range closest to the magnetoresistive element, a green light emitter is lit when the piston is in a certain dangerous range outside the optimum range.

[0003]

However, in the magnetic sensor configured as described above, even if the setting is deviated due to the influence of vibration or the like and becomes a dangerous range, it can be confirmed only by visual observation of the light emitting body. Met.

Therefore, when a large number of such magnetic sensors are provided for each device of a plant, it is necessary to visually check the illuminant for each device to determine the display color, which is very difficult. there were.

A first object of the present invention is to make it easier to determine the danger area of a piston by adding a danger area output circuit to the conventional magnetic sensor described above.

A second object of the present invention, in addition to the first object, is to centrally manage the position of each piston at a location remote from each cylinder.

[0007]

In order to achieve the first object, according to the first aspect of the present invention, a piston is movably provided in a cylinder tube, a magnet is provided on the piston, and the piston is provided with a magnet. In a cylinder piston position detecting device provided with a magnetic sensor on the outside for detecting the magnetism of the magnet, the magnetic sensor includes a magnetoresistive element that generates an output having a magnitude corresponding to a distance from the magnet, A case where the magnet is located within a certain range from a position closest to the element is detected as an optimum sensitivity detection band, and a case where the magnet is located within a certain range deviating from the optimum sensitivity detection band is used as a danger sensitivity detection band. A detection circuit for detecting, a light emitting circuit for operating a light emitting element in each of these bands based on the detection signal, and a danger sensitivity detection band The danger signal output in conjunction with the operation of the light emitter and a critical region output circuit for externally outputting.

In order to achieve the second object, in the invention according to the second aspect, a plurality of cylinder position detecting devices according to the first aspect are arranged, and the piston position management of the cylinder which manages each of these devices. A danger signal input unit connected to each danger area output circuit provided in each of the magnetic sensors and capable of intensively inputting a danger signal output from each of the danger area output circuits; And a display unit corresponding to the magnetic sensor that outputs the danger signal output input to the danger signal input unit.

[0009]

Therefore, in the invention according to the first aspect, the luminous element performs a safety display when the output of the magnetoresistive element is in the optimum sensitivity detection band, and a danger display when the output is in the danger sensitivity detection band. Further, when the output of the magnetoresistive element is in the danger sensitivity detection band, the output from the danger area output circuit is generated.
A danger signal output is issued to the outside together with the danger display by the light body .

[0010] In the invention according to claim 2, in addition to the above-mentioned operation, a danger signal input unit capable of intensively inputting a danger signal output from each danger area output circuit is provided. Since the display unit corresponding to the magnetic sensor that outputs the input danger signal output is operated, it is possible to centrally manage the piston position of each cylinder at a predetermined location away from each cylinder.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a magnetic proximity switch 1 as a magnetic sensor. A magnet 4 (magnet) is fitted to a piston 3 in an air cylinder tube 2 and a sensor case 5 is fixed outside the tube 2. .
A circuit board 6 is provided in the sensor case 5, and FIG.
The circuit on the circuit board 6 shown in FIG. 1 has a magnetoresistive element 7 connected to the magnet 4 of the piston 3 and a green light emitting diode 8 and a red light emitting diode 9.
(Light emitter) is connected.

Next, the circuit shown in FIG. 2 will be described in detail.
The magnetoresistive element 7 is connected between a power supply line 10 (plus output line) and a ground line 11 (minus output line) via a constant current circuit 12, and the magnetoresistive element 7 has a magnetic field strength. , The voltage at the midpoint C decreases.
The detection circuit 13 includes a first operational amplifier 14 having a high threshold value.
(Comparator) and second operational amplifier 1 with low threshold
5 (comparators), and their input terminals are connected to the midpoint C of the magnetoresistive element 7, respectively.

Reference numerals 16 and 17 denote first and second light emitting circuits, respectively, and reference numeral 22 denotes an output circuit. The output circuit 22 has a transistor 23, a bypass line 22 a is connected between the collector and the power supply line 10 in parallel with the light emitting circuits 16 and 17, and the emitter is connected to the ground line 11. . The first light emitting circuit 16 has a resistor 18, a green light emitting diode 8 and a transistor 19 connected in series, and the second light emitting circuit 17 has a resistor 18, a red light emitting diode 9, a transistor 20 and a transistor 21 connected in series. The light emitting circuits 16 and 17 are connected in parallel to each other and the power supply line 10 and the transistor
Connected between the base. The base of the transistor 20 is connected between the green light emitting diode 8 and the collector of the transistor 19. First operational amplifier 14
Is connected to the base of the transistor 21 via the resistor 24, and the output terminal of the second operational amplifier 15 is connected to the base of the transistor 19 via the resistor 25.

A dangerous area output circuit 26 is connected between the power supply line 10 and the ground line 11 in parallel with the light emitting circuits 16, 17 and the output circuit 22. The dangerous area output circuit 26 has a pair of transistors 27 and 28. The collector of the transistor 27 is connected to the base of the transistor 28 via a resistor 29. The base of the transistor 27 is connected to the red light emitting diode 9 and the transistor 20. Is connected via a resistor 30 to the collector. In particular, transistor 28 is an open collector 28
a, and this is the output line 26a dedicated to the danger sensitivity.
Is configured.

The magnet 4 is a magnetic proximity switch 1
When approaching again after gradually approaching the magneto-resistive element 7, the strength of the magnetic field acting on the magneto-resistive element 7 gradually increases to a maximum value, and then gradually decreases. As shown in FIG. 3, it gradually decreases and reaches the lowest value, and then gradually increases. When the voltage drops below the threshold value H of the first operational amplifier 14, its output goes to a high potential, and the voltage further decreases to reduce the second operational amplifier 1
When the voltage falls below the threshold value L of 5, the output becomes a high potential.

If the voltage at the middle point C is higher than the threshold value H of the first operational amplifier 14, the outputs of both the operational amplifiers 14 and 15 are at a low potential. The switch 1 is turned off, and a dark current at a level at which the photocoupler of the sequencer (not shown) connected thereto does not operate flows between the power supply line 10 and the ground line 11.

When only the output of the first operational amplifier 14 is at a high potential, the transistor 19 is turned off, the base of the transistor 20 is at a high potential, the collector and the emitter of the transistor 20 are turned on, and the transistor 21 is turned on. High potential output is sent to the base and transistor 2
When the first collector and emitter are turned on and the transistor 23 of the output circuit 22 is turned on, a current flows through the second light emitting circuit 17 and the red light emitting diode 9 is turned on. As a result, the proximity switch 1 is turned on, and the photocoupler of the sequencer (not shown) operates to determine the state of the switch 1.

When the output of the second operational amplifier 15 also has a high potential, a high potential output is sent to the base of the transistor 19 to turn on the collector and the emitter of the transistor 19 and turn on the transistor 23 of the output circuit 22. As a result, a current flows through the first light emitting circuit 16 to turn on the green light emitting diode 8, and the output to the base of the transistor 20 becomes low potential, turning off the transistor 20 and turning off the red light emitting diode 9. . Again,
The proximity switch 1 is turned on, and the photocoupler of the sequencer (not shown) operates to determine the state of the switch 1.

In particular, when a current flows through the second light emitting circuit 17 and the red light emitting diode 9 is turned on, the base of the transistor 27 of the dangerous area output circuit 26 becomes low potential, and the emitter and the collector of the transistor 27 are turned on. Further, when a high-potential output is sent to the base of the transistor 28 to turn on between the collector and the emitter of the transistor 28, a danger signal output S is generated at the open collector 28a of the transistor 28. With this output S, an alarm can be issued only when the red light emitting diode 9 is turned on to notify that the vehicle is in the dangerous range.

In this embodiment, the two light emitting circuits 1 are used.
Since the dangerous area output circuit 26 is added in addition to 6 and 17, not only can the light emitting diodes 8 and 9 be visually confirmed, but also the dangerous area output circuit 26 provides a dangerous signal output S that is within the dangerous range. Can be determined, and the determination becomes very easy.

Further, the lead wires need only be of a three-wire type by adding a hazard sensitivity output line 26a to the two-wire type of the power supply line 10 and the ground line 11, so that the connection is easy. next,
A system for centrally managing the magnetic proximity switch 1 configured as described above will be described in detail.

As shown in FIG. 4, a plurality of magnetic proximity switches 1A to 1E are provided via a control unit 31 to a central management unit 32.
It is connected to the. The danger signal outputs SA to SE of the magnetic proximity switches 1A to 1E are combined into one by a danger signal management unit 33 (danger signal input unit).
Is further connected to the central management unit 32.

When a danger signal output SA to SE is generated in any one of the danger area output circuits 26 of the magnetic proximity switches 1A to 1E, the danger signal output is sent to the central management unit 32. Has become. In the danger signal management unit 33, each of the proximity switches 1A to 1E
A light emitting diode (not shown) as a display unit is connected to each of the danger signal outputs SA to SE. Thereby, the state of each of the proximity switches 1A to 1E can be checked at a glance.

As described above, each of the magnetic proximity switches 1A to 1E
If the danger signal outputs SA to SE of the magnetic proximity switches 1A to 1E are managed by the central management unit 32, and the danger signal outputs SA to SE of the magnetic proximity switches 1A to 1E are managed at a glance, The state of ~ 1E is known and management becomes very easy, and as a result, maintenance and operation rate are improved, and it is suitable for introduction to an unmanned line.

[0025]

As described in detail above, according to the present invention,
Since the judgment can be made based on the danger signal output from the danger area output circuit in addition to the conventional visual observation of the light emitter, the management becomes very easy. Therefore, when an abnormality such that the object to be detected moves little by little from the arrangement position of the magnetic sensor or an abnormality such that the magnetic sensor moves little by little from the desired position occurs, the abnormality is detected before the abnormality exceeds a certain allowable range. Measures can be taken. Moreover, if the hazardous area output circuits of the plurality of magnetic sensors are centrally managed, it is not necessary to check the illuminant provided for each magnetic sensor, so that the management of the plurality of magnetic sensors can be easily performed. it can. Further, by providing a display unit at the location where the centralized control is performed and operating the display unit corresponding to the magnetic sensor that has output the danger signal, it is possible to perform a centralized control of the occurrence of abnormalities visually, thereby facilitating the centralized control. There are effects that can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a magnetic proximity switch according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of the proximity switch.

FIG. 3 is an explanatory diagram showing the relationship between the output of a magnetoresistive element, the output of a light emitting circuit, the output of a dangerous area output circuit, and the operation of a proximity switch.

FIG. 4 is a block diagram showing a centralized management system using a plurality of proximity switches.

[Explanation of symbols]

1: magnetic proximity switch (magnetic sensor), 3: piston,
4 ... magnet (magnet), 7 ... magnetoresistive element, 8 ... green light emitting diode (light emitting body), 9 ... red light emitting diode (light emitting body), 13 ... detection circuit, 14 ... first operational amplifier (comparator), 15 ... Second operational amplifier (comparator), 16 first light emitting circuit, 17 second light emitting circuit, 22 output circuit, 26 dangerous area output circuit, 26a
... Danger sensitivity dedicated output line, 28a ... Open collector.

Claims (2)

(57) [Claims] A piston (3) is movably provided in a cylinder tube (2), and a magnet (4) is provided on the piston (3), and the magnet (4) is provided outside the cylinder tube (2). In the cylinder piston position detecting device provided with a magnetic sensor (1) for detecting magnetism, the magnetic sensor (1) generates an output having a magnitude corresponding to a distance from the magnet (4). (7) detecting a case where the magnet (4) is located within a certain range from a position where the magnet (4) is closest to the magnetoresistive element (7) as an optimum sensitivity detection band, and deviates from the optimum sensitivity detection band. And a light emitting circuit (8, 9) for operating the light emitters (8, 9) in these bands based on the detection signal. And 6,17), operating dangerous signal output to match the light emitter (8) in the risk sensitivity detection zone (S)
And a dangerous area output circuit (26) for externally outputting the piston position. Wherein the piston position detector according to claim 1, wherein the cylinder a plurality of arranged, a piston position managing apparatus of the cylinder for managing these devices, provided to the each magnetic sensor (. 1A-1 E) The dangerous signal output (SA-S) is connected to each of the dangerous area output circuits (26).
A danger signal input unit (33) capable of intensively inputting E);
A display unit provided corresponding to each of the magnetic sensors (1A to 1E), and a danger signal output (SA to SE) input to the danger signal input unit (33);
A centralized control device in a cylinder piston position detecting device, wherein a display unit corresponding to A to 1E) is operated.