KR20140137134A - Explosion proof proximity sensor detecting doors of equipment open or close in hazardous area - Google Patents

Abstract

The present invention relates to an explosion-proof proximity sensor for detecting the opening and closing of a storage box door in an explosion-proof area containing a control device for storing and transporting a flammable liquid or gas having a risk of explosion. More specifically, the present invention relates to a method of controlling a door of an open-close device in which an explosion-proof sensor is provided with a proximity sensor having a circuit portion operated at a current intensity satisfying the NAMUR standard, And a signal is sent to the control device by sensing the closing. The proximity sensor according to the present invention can output a non-detection signal by controlling the size, shape and inclination of the subject to be detected, unlike the conventional proximity sensor, even when the door of the opening and closing device is slightly opened.

Description

[0001] The present invention relates to a proximity door sensor for detecting opening / closing of an equipment door in an explosion-proof area,

The present invention relates to an explosion-proof sensor for detecting whether a door is opened or closed in a dangerous area such as an explosion-proof area, and more particularly, to an explosion-proof sensor for detecting the opening / An inductive type or capacitive proximity sensor having an explosion-proof function is installed on one side, and a sensor to be detected is installed on one side of the door of the storage box so as to detect that the door of the storage box is not completely closed or opened. To a proximity door sensor.

In recent years, an explosion occurred in various industrial sites, causing damage to property as well as property damage. In some cases, products and components of electrical and electronic equipment in explosive areas may be sources of ignition, which may be the cause of an explosion, due to poor equipment or management, but also to the cause of the explosion. As the awareness of explosion increases and regulations and management of the government are strengthened, explosion-proof performance of all electric and electronic devices is demanded.

As shown in Fig. 1, in industrial sites dealing with flammable liquids or gases, it is necessary to install control devices for storage and transport close to or near liquids or gases in the explosion-proof area and to place power devices in remote areas have. When installing control equipment in an explosion-proof area, place it in a large metal enclosure or box to isolate it from physical hazards.

When the door is opened and closed frequently to manage the electrical and electronic control devices in a metal enclosed storage cabinet. If the door is accidentally opened or not completely closed, flammable gas may seep into the metal storage box or liquid may enter and cause an explosion. Install a sensor that detects if the door is completely closed.

Until now, we have installed a magnetic reed switch that uses a simple contact type switch or a magnetic property to change the door opening / closing signal into a signal and observe it in a remote monitoring system. The contact type switch has a simple circuit. When the door is closed, a closed circuit is formed to output a signal. When the door is opened, an open circuit is opened to cut off the signal. However, the contact point is directly exposed to the explosion- When the switch is opened, the overcurrent may flow into the switch, which makes the safety check more difficult and difficult to use.

The magnetic switch frequently detects that the door is closed in the surveillance system because the detection distance is long and the door is not completely closed and the door is still open even though it is slightly open. Because of this phenomenon, the magnetic switch and the object to be detected may be installed at the end of the detection limit. However, errors may occur in each product, and the position may be corrected by pulling it again after the installation. When the flammable liquid or gas is actually put into the explosion-proof area after the installation of the storage box is completed, the reed switch should be positioned according to the product specification, so that it can not be punched again to move the installed switch. Therefore, when the sensing distance is not constant, a serious problem occurs.

Up to now, conventional industrial inductive proximity sensors have used ferrite cores. Since the storage box installed in the explosion-proof area is made of metal and because of the nature of opening and closing doors, it can not attach a heavy sensor, it can be replaced with existing contact type switch or magnetic switch in similar shape or size. If you replace the sensor with a ferrite core like an inductive sensor, you can not control the sensing distance. It is difficult to configure the sensor to detect the sensor when the door is opened slightly. The capacitance type proximity sensor needs to adjust its direction and size so that the electric field formed in front of the sensing part is limited to the sensing target due to the influence of the surrounding environment. However, the sensing part of the conventional capacitive sensor has a special purpose It is not easy to adjust the shape of the electric field.

[Document 1] 1010710710000 (Sep. 30, 2011), Capacitive Level Monitoring System [Document 2] 1007269350000 (2007.06.04), Capacitive leak sensor

The present invention solves the above problems and provides an inductive type or capacitive proximity sensor which is driven by a low power which satisfies the NAMUR standard because of the characteristics of an explosion-proof area and has a characteristic of accurately detecting only a short distance. More specifically, a rectangular parallelepiped-shaped sensing object (to-be-detected) similar to or slightly larger than the proximity sensor is installed at one side of the door for opening and closing, and the explosion-proof proximity sensor is provided with a rectangular parallelepiped shape It is installed on one side of the inside of the storage box so that when the door is closed, the sensing surface of the sensor is close enough to touch the object. Even if it is not a rectangular shape, it can be fixed to a storage box or a door, and the object to be sensed attached to the door is slightly moved so that the door is not closed properly.

In contrast to the inductive proximity sensor using a conventional ferrite core, the shape of the object to be detected must be configured in a different manner to replace the contact type or the magnetic reed switch. Therefore, the existing inductive proximity sensor used in the industrial field has a limit, so it must be attached to one side of the door to be small, light enough to replace the existing switch, and have a characteristic of coming out exactly as the distance is set. Also, if the door is slightly open, it should have a structure that can signal. Further, in the capacitive proximity sensor, the shape and intensity of the electric field formed on the sensor front surface of the sensor should accurately detect the movement of the subject.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, an inductive sensor according to an embodiment of the present invention includes a circuit part driven by a low power and a ferrite core and a magnetic field strength so that the sensor can sense the movement of the to- A coil that does not contain a ferrite core, a housing that can be fixed to the wall of the storage box, including a circuit part and a coil, and a sensing part And a target object (target). Proximity sensors that attach to the inside of the storage compartment include indicators such as LEDs that receive a non-sensing signal to easily recognize the naked eye from the outside when the door is opened.

The capacitance type proximity sensor according to another embodiment of the present invention is configured to detect the shape of the sensing electrode of the sensing unit so that the electric field senses the position of the sensing target and then emits a signal in a non- do.

Since the sensor is driven with low power to produce a weak signal that meets explosion-proof conditions, the signal from the sensor uses the barrier to supply the driving power and transmit it to the control device such as PLC. Surveillance devices in safety areas can be signaled directly from the barrier or transmitted via a control device, and cables for supplying signals or power are selected for explosion-proof products conforming to international explosion-proof regulations.

The explosion-proof door sensor according to an embodiment of the present invention can be installed at one side of a storage compartment of electrical and electronic equipment in an explosion-proof area to detect the state of opening and closing and operates at a low power to provide a cause of explosion It can be used safely. The contact type switch or the magnetic reed switch installed in the existing explosion-proof area can be replaced without changing the structure of the equipment or the storage box.

FIG. 1 is a view showing a configuration of an explosion-proof area in which a door sensor is installed
FIG. 2 is a view showing the configuration of a door sensor in a metal box installed in an explosion-
Fig. 3 is a diagram showing the configuration of the housing and the circuit portion,
4 is a structural view of an inductive type door sensor according to the present invention.
FIG. 5 is a graph showing the results obtained when a conventional inductive sensor
FIG. 6 is a block diagram of the sensing unit of the capacitive sensor according to the present invention.
FIG. 7 is a schematic diagram of a sensing and non-sensing state according to the structure of a capacitive door sensor according to the present invention
FIG. 8 is a graph showing the relationship between the detected and non-

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of preferred embodiments of the present invention will be given with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Fig. 1 is a schematic diagram of a place where the present invention is applied. Explosion-proof areas are areas where explosive hazardous substances are always present in zone 0, explosive hazardous materials are in enclosed containers, and areas exposed to frequent explosion hazards are zone 1 Areas in the vicinity of the container of the causing material that are frequently covered by explosive materials when exposed to a small amount of hazardous materials, or zones 2 that are likely to be exposed to explosive hazards when a large amount of hazardous materials are poured out. "He said.

Storage and transport of explosive hazardous materials in storage tanks uses a valve or a pump-like drive through the piping. A metal box (600) is installed in the explosion-proof area to control these devices, (300). The power unit 500 and the surveillance unit 400 are located in a non-explosion area and enclose the cable in various ways to prevent explosion to transmit power and receive a signal to the metal enclosure 600 in the explosion-proof area.

2 is a view showing the structure inside the metal box. When setting the controller 300 such as the PLC contained in the metal box 600 or changing the set value later, the door 130 in the metal box 600 is opened and the door for the dangerous substance outside is opened The door sensor 100 is installed to prevent the door 130 from coming into the metal case 600 through the door 130. When the door 130 is opened for a predetermined time or longer, an alarm signal is output. The door sensor 100 includes a sensor unit 110 with a wire 118 and a target 120 with which the sensor senses the wire 118. The sensor 118 is fixed to the inside of the storage unit 140, Are installed in the door 130. Since the signal from the sensor 110 is low in current, the barrier 200 having explosion-proof performance is used to amplify the sensing signal of the sensor and input a signal for opening and closing the door 130 to the control device 300.

FIG. 3 is a diagram showing a housing structure and an internal structure of an explosion-proof inductive proximity sensor, as one embodiment according to the present invention. The circuit part of the sensor is constituted by a sensing part 113, an oscillation part 114, a detection part 115 and an amplification part 116 like a general inductive proximity sensor and is installed on a PCB substrate 117 as a printed circuit board, , The intensity of the current flowing through the circuit is set to be low according to the NAMUR regulation (German Chemical Society explosion-proof regulation). The circuit unit and the target use a housing 121 of the same size, and the housing is fixed to the metal case 600 with a screw so that the perforation 126 is inserted. A metal object to be detected 122 is inserted into the housing 121 used as a target. In addition, a light guiding unit 119 for indicating that the door 130 is opened and closed is installed in the housing 111 of the sensor, so that the opening and closing of the door 130 can be easily confirmed visually.

4 (a) is a view showing the ferrite core 112, the coil 113, the metal objects 122, and 122 inside the housing according to the present invention when the door 130 is opened. A change in the intensity of a vortex generated in the center of the ferrite core 112 wound around the coil 111 in the housing 111 and coming out of the magnetic field and coming out of the detected member 122 lying in the magnetic field is sensed by the circuit portion of the sensor. The metal object 122 in the housing 121 is tilted and sized according to the turning radius R (125) of the door 130, unlike the object to be inspected of the conventional inductive sensor. Otherwise, if the object to be detected 126 is vertically arranged with respect to the door 130 like the conventional sensor shown in FIG. 5 and the entire size of the object is detected, the door 130 is continuously detected even when the door 130 is slightly opened, And the door is opened because the detection signal is out.

The door 130 may be formed at a corner of the housing 121 so as to be opened without touching the door frame 140 of the metal housing when the turning radius R 125 is considered, The position 123 is determined and the inclination of the metal-covered body 122 of the target is determined. That is, the inclination of the detected object 122 is related to the turning radius R (125) of the door 130.

5 (b) and FIG. 4 (b), when the door 130 is slightly opened at about 6 degrees as shown in the illustration, When it is opened a little, it senses unlike the conventional sensor and signals that the door (130) is open.

FIG. 6 is a diagram illustrating the sensing unit 150 in detail to be applied to the explosion-proof circuit of FIG. 3 as the capacitive proximity sensor according to another embodiment of the present invention. A lower voltage electrode is used for the sensing electrode of the capacitance type leak sensor (registration number: 1007269350000 (2007.06.04)) and the capacitance type water level detection system (registration number: 1010710710000 (September 30, 2011) And the electric field formed on the front surface of the sensing electrode is more narrowly oriented in the direction of the object to be detected. The center of the sensing portion is a part of the line of electric force exiting from the anode portion 153 goes out to the cathode portion 155 behind the electrode fixing substrate 154 which is a part of the insulator and to a part of the cathode portion 152 connected to the cathode portion 155 And most of them come out of the anode part 153. In the present invention, another cathode portion 151 having a potential substantially equal to (-) of the power supply portion is added to the outside of the cathode portion 152 to partially absorb the electric force line exiting from the anode portion 153, The leakage of the electric power line is prevented to improve the directivity.

FIG. 7 is a diagram illustrating a state in which the metal object to be detected 128 is sized and tilted along the radius R 125 of the door surface of the door 130 by the application of another embodiment of the present invention, So that it can emit a signal in a non-sensing state. 8 is a diagram illustrating a state in which a metal object to be inspected is installed at the same size and slope as a conventional sensor when the sensor unit 150 according to the present invention is applied, Respectively.

As described above, preferred embodiments of the present invention have been disclosed in the present specification and drawings, and although specific terms have been used, they have been used only in a general sense to easily describe the technical contents of the present invention and to facilitate understanding of the invention , And are not intended to limit the scope of the present invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: door sensor 200: barrier (amplifying device)
300: Control device 400: Monitoring device
500: Power unit
110: door sensor 120: object housing (target)
130: Door 140: The door of the metal enclosure is closed

Claims (5)

It is installed on one side of the inside of a metal box for storing electric and electronic equipment that controls devices that store and transport flammable liquids or gases that are explosive dangerous. It is fixed to the door of the opening and closing device that opens and closes the housing including the body to be inspected. A sensor unit for detecting opening and closing of the door of the apparatus,
A plastic housing surrounding a to-be-detected body made of metal is fixed to one side of a door of an opening / closing device,
A proximity sensor of an opening and closing device comprising an amplifying part having a function of amplifying a sensing signal outputted from a sensor and inputting it to a control device.
The method according to claim 1,
An inductive proximity sensor having a function of detecting a ferrite core and a ferrite core wound around the ferrite core and a ferrite core or a coil only to sense the target body when the target body is a metal or an electrode unit of the sensing unit to be oriented in a narrow electric field Configurable capacitive proximity sensor.
3. The method of claim 2,
The circuit is a proximity sensor that is driven by the current strength that meets the NAMUR standard, which is the circuit standard of the explosion-proof sensor.
3. The method of claim 2,
A proximity sensor including a light shielding portion which is openable and closable in accordance with the position of the body to be detected and which can be visually identified by light. The method according to claim 1,
A proximity sensor in which the size and inclination of the body to be detected made of metal have a constant proportional relationship with the turning radius of the opening and closing device when the housing surrounding the body to be detected is fixed to one side of the opening and closing device.

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