JP5223147B2 - Internal pressure explosion-proof device at the boundary of hazardous area - Google Patents

Description

The present invention relates to an internal pressure explosion-proof device that can be used for a paint supply device, a conveyor drive device, and the like in a paint factory.

A passive device such as a cylinder pump or conveyor equipment is installed in a hazardous area, a power device such as a motor is installed in a non-hazardous area, and a device that connects the passive device and the drive device with a drive shaft is used for explosion-proof problems. could not.
The reason for this is that through holes for the drive shaft are required on the walls of the hazardous area and non-hazardous area, and flammable gas leaks from the hazardous area to the non-hazardous area through the through hole and shaft bearing. There was an explosion-proof problem.
Therefore, there are passive devices such as paint pump cylinders and conveyor power shafts in hazardous areas where flammable gas exists, and non-hazardous areas include motors and other driving devices. In the device that has a through hole of the drive shaft that connects the passive device and the drive device on the wall of the wall, by installing an explosion-proof case on the wall on the non-hazardous side, and making the through hole part of the drive shaft an internal pressure explosion-proof structure, It is devised so that a driving device such as a non-explosion-proof motor can be used without using a driving device such as a pressure-proof explosion-proof motor or an internal pressure explosion-proof motor.

Japanese Patent No. 2796482 Japanese Patent No. 3702404 Japanese Patent Publication No. 07-004792 Japanese Patent Laid-Open No. 06-339890 JP 2006-321041 A

In a device with a drive shaft that penetrates the wall between the hazardous area and the non-hazardous area, flammable gas leaks from the hazardous area to the non-hazardous area at the penetration part of the drive shaft, which may cause an explosion and is an explosion-proof problem. It was. Therefore, an apparatus having such a structure cannot be used.

An internal pressure case with a highly confidential internal pressure chamber is provided on the non-hazardous area side of the boundary between the hazardous area and the non-hazardous area. This allows use in devices with drive shafts that penetrate the walls of hazardous and non-hazardous locations.

Conventionally, in a device having a drive shaft that penetrates the wall between a dangerous place and a non-hazardous place, a device having a structure in which flammable gas leaks from a dangerous place to a non-hazardous place at a penetration portion of the drive shaft cannot be used. Therefore, it is necessary to install the drive device in a hazardous area and use a pressure-proof explosion-proof motor or an internal pressure explosion-proof motor.
If the internal pressure explosion-proof device according to the present invention is used, the drive device can be installed in a non-hazardous area, and it is not necessary to use an expensive explosion-proof motor or internal pressure explosion-proof motor. Can be made cheaper.

Configuration conceptual diagram showing Embodiment 1 of the present invention Configuration conceptual diagram showing Embodiment 2 of the present invention Configuration conceptual diagram showing a conventional problem example

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows the case where a passive device cylinder is installed in a hazardous area, a motor and actuator of a driving device are installed in a non-hazardous area, and the passive device in the hazardous area and the driving apparatus in a non-hazardous area are connected by a drive shaft. Examples will be given.
A dotted line in the figure indicates an electric wire, and a solid line indicates an air hose.
As shown in FIG. 1, the cylinder 24 is installed in a dangerous place where flammable explosion-proof gas or the like exists, and the motor 21 and the actuator 22 are installed in a non-hazardous place where flammable explosion-proof gas or the like does not exist.
The drive shaft 23 connects the cylinder 24 and the actuator 22 and passes through the drive shaft through hole 30 at the boundary between the dangerous place and the non-hazardous place.
The drive shaft 23 drives the piston in the cylinder 24 by the power of the motor 21.
The bearings 2 and 3 are provided in the internal pressure case 1 as bearings for the drive shaft 23.
The internal pressure case 1 has a highly confidential structure, and is provided with internal air supply ports 4 and 5, an exhaust air pressure relief valve 7, an exhaust air scavenging port 8, and an internal pressure air pressure drop detector 6.
Air is supplied into the internal pressure case 1 from an air source (not shown) from the hand valve 13 via the air hose 19 to the pressure reducing valve 12 and from the pressure reducing valve 12 via the air hose 19A. From the solenoid valve 9 to the air supply port 4 via the air hose 19H, from the solenoid valve 9 to the solenoid valve 10 via the air hose 19B, and from the solenoid valve 10 via the air hose 19L. Air is supplied to the air supply port 5.
Air pressure is P1 (supply air pressure high), P2 (pressure relief valve exhaust air pressure), P3 (supply air pressure low), P4 (internal pressure case internal air pressure), P5 (exhaust air pressure), P6 (bearing) (Part leakage air pressure) and P7 (bearing part leakage air pressure), the pressure relationship is P1>P2>P3>P4> P5 = P6 = P7> atmospheric pressure.
At this time, the air pressure of P1 is adjusted by the pressure reducing valve 12, and the air pressure of P3 is adjusted by the pressure reducing valve 11.
When starting the internal pressure explosion-proof device, there is a possibility that flammable gas is mixed in the internal pressure case 1, so it is necessary to replace the air in the internal pressure case 1.
The control of replacing the air inside the internal pressure case 1 is performed by first supplying the air pressure at a high pressure to scavenge the flammable gas in the internal pressure case 1 and then supplying it at a low air pressure to adjust the air pressure in the internal pressure case 1 to the atmospheric pressure. The mixture should be made higher to prevent flammable gas contamination.
When the hand valve 13 is opened while the solenoid valve 9 is in the excited state and the solenoid valve 10 is in the non-excited state, the air adjusted by the pressure reducing valve 12 is sent to the air supply port 4 through the solenoid valve 9 (P1). The air is exhausted from the pressure relief valve 7 (P2), the exhaust port 8 (P4), the bearing 2 (P6), and the bearing 3 (P7).
If the monitored pressure of the pressure drop detector 6 is equal to or higher than the set pressure after a certain time has elapsed, the electromagnetic valve 9 is de-energized, then the electromagnetic valve 10 is energized, and the air adjusted by the pressure reducing valve 11 is Air (P3) is supplied to the air supply port 5 through the valve 10, and air is exhausted from the exhaust port 8 (P4), the bearing 2 (P6), and the bearing 3 (P7).
Control of air and pressure monitoring are controlled by a control device (not shown), and the pressure drop detector 6 is constantly monitored during supply, and when the pressure falls below the set pressure, a protection circuit is activated to shut off the power. It has a function to prevent the occurrence of ignition and explosion.

Fig. 2 shows the case where the power shaft of the passive device is installed in the hazardous area, the motor of the drive device is installed in the non-hazardous area, and the passive device in the hazardous area and the drive apparatus in the non-hazardous area are connected by the drive shaft. Examples will be given.
A dotted line in the figure indicates an electric wire, and a solid line indicates an air hose.
FIG. 2 shows an example in which only the driving device and the passive device are different from the first embodiment shown in FIG.
The difference in the driving device is that the motor 21 and the actuator 22 are used in FIG. 1, whereas the motor 21 and the coupling are used in FIG.
The difference between the passive devices is that the cylinder 24 is used in FIG. 1, whereas the spur gear 25 and the power shaft 26 are used in FIG.
Except for the driving device and the passive device, the second embodiment is the same as the first embodiment, and thus detailed description of the second embodiment is omitted.

FIG. 3 shows a conventional problem example.
An example in which a motor drive device is installed in a hazardous location, a cylinder passive device is installed in the hazardous location, and a passive device in the hazardous location and a drive device in a non-hazardous location are connected by a drive shaft will be described.
The apparatus as shown in FIG. 3 has a drive shaft through hole 30 in the wall between the dangerous place and the non-hazardous place, and the flammable gas P8 is transferred from the dangerous place to the non-hazardous place through the gap of the bearing 3 of the drive shaft through hole 30. Leak.
If the flammable gas P8 leaks into a non-hazardous area, there is a risk of explosion, so that the structure as shown in FIG. 3 is prohibited because it is not recognized as an explosion-proof structure.

DESCRIPTION OF SYMBOLS 1 Internal pressure case 2.3 Bearing 4/5 Supply port 6 Pressure drop detector 7 Pressure relief valve 8 Exhaust port 9/10 Solenoid valve 11/12 Pressure reducing valve 13 Hand valve 19 / 19A / 19B / 19L / 19H Air hose 20 Control device 21 Motor 22 Actuator 23 Drive shaft 24 Cylinder 25 Spur gear 26 Power shaft 27 Coupling 30 Drive shaft through hole P1 Supply air pressure high P2 Pressure relief valve exhaust air pressure P3 Supply air pressure low P4 Internal pressure case internal air pressure P5 Exhaust air pressure P6, P7, P8 Bearing section leakage air pressure

Claims (2)

In an apparatus having a drive shaft passing through a wall between a hazardous area and a non-hazardous area, an internal pressure case having a highly sensitive internal pressure chamber on the wall on the non-hazardous area side of the boundary between the hazardous area and the non-hazardous area; , Built-in air supply valve and exhaust port, pressure relief valve, air pressure drop detector and shaft bearing in the internal pressure case prevent the mixture of flammable gas by making the air pressure in the internal pressure case higher than the hazardous area Internal pressure explosion-proof device at the boundary of hazardous area with mechanism. The air pressure adjustment in the internal pressure case is provided with an exhaust port that takes into account the amount of leakage from the clearance of the shaft bearing, and has a function of shutting off power when a decrease in air pressure is detected. 1. An internal pressure explosion-proof device at the hazardous location boundary.

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