JPS5927441B2 - Explosion-proof structure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flameproof explosion-proof structure for equipment that energizes an actuating element by excitation of an excitation coil.

This type of equipment includes electro-pneumatic converters, electro-pneumatic positioners,
There are solenoid valves, etc., but when these are used in hazardous locations such as explosive gas atmospheres, the equipment is required to have sufficient explosion-proof performance.

Various explosion-proof structures have been proposed and implemented to provide this explosion-proof performance, and the pressure-resistant explosion-proof structure of an electro-pneumatic positioner shown in FIG. 1 is a typical example.

Briefly explaining the electro-pneumatic positioner shown in the figure, reference numeral 1 denotes a main body case and a two-pin terminal board case, which have a pressure-resistant and explosion-proof structure in combination with a main body case cover and a terminal board case cover (not shown).

3 is a torque motor, which includes an excitation coil 4 and a leaf spring 6 for a fulcrum.
A cable 8 that connects the excitation coil 4 and the terminal plate 7 is fixed to the terminal plate case 2 with a packing 9, a washer 10, and a tightening member 11, and this pressure-resistant packing retraction structure This connects the main body case 1 and the terminal plate case 2 in a pressure-resistant and explosion-proof structure.

A nozzle 12 faces the balance beam 5, and the nozzle 12 and the balance beam 5 constitute a nozzle flapper mechanism.

13 is a supply air pressure piping port, 14 is a fixed throttle for nozzle back pressure, 15 is a pilot valve, 16 is an output pressure outlet, 17 is an actuator, and 18 is a feedback mechanism for feeding back the movement of the actuator 17. The movement of the actuator 17 is transmitted from the feedback lever 19 to the feedback spring 25 via a shaft 20, a link 22, a range adjuster 23, and a link 24 passing through a bearing 21 having an explosion-proof gap.

In such an electro-pneumatic positioner, if the excitation coil 4 is now excited, the balance beam 5 will change depending on the amount of current.
is displaced to the left and blocks the nozzle 12, increasing the nozzle back pressure. This nozzle back pressure is amplified by the pilot valve 15 to become specific pressure, which is guided to the actuator 17.

The movement of the actuator 17 due to this output pressure is transmitted through the feedback mechanism 18 as a force that displaces the balance beam 5 to the right, and the input current to the excitation coil 4 causes a force to be applied to the balance beam 5 to the left. Balance and stop the movement of the balance beam 5.

However, in a device configured as described above, the entire body case 1 and terminal board case 2 must be made of flameproof and explosion-proof type, and furthermore, the connection points and sides of the cases 1 and 2 and these covers must be All parts of the body case 1 communicating with the atmosphere (nozzle flapper piping hole 26, bearing 21, bleed hole 27, etc.), including the joint between cases 1 and 2, must be configured to exhibit pressure-proof and explosion-proof properties. However, satisfying all of these requirements would not only make the entire device larger, heavier, and extremely expensive, but it would also be impossible to open the lid and adjust, repair, or replace the nozzle flapper mechanism or feedback mechanism on site. This inevitably results in equipment that is extremely difficult to handle.

In order to solve the above-mentioned difficulties, the present invention provides a device that energizes an actuating element by excitation of an excitation coil as described above, in which only an electric drive member such as an excitation coil is fixed in a sealed container, and the excitation coil is is characterized in that another mechanical operating element that is activated by the excitation of is provided within the non-explosion-proof housing,
Furthermore, when the operating element operates by minute displacement, such as in a nozzle flapper mechanism, the mechanical displacement caused by the excitation of the excitation coil can be transmitted to the operating element in an explosion-proof manner with a simple structure and an extremely small resistance force. It is characterized by the fact that

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In FIG.
Reference numeral 1 denotes a terminal board case made of a hermetically sealed explosion-proof container; 32 a non-explosion-proof housing housing an operating element 34 actuated by the electric drive member;
The driving member case 30 and the terminal plate case 31 are still connected in a pressure-proof and explosion-proof manner by a pressure-proof packing retraction structure similar to that shown in FIG.

The balance beam 3 is swingably supported by the electrical drive member 33, the excitation coil 36, and the fulcrum plate spring 38.
It includes a torque motor 35 consisting of 7 etc., and an excitation coil 36.
and the terminal board 39 are the driving member case 30 and the terminal board case 3.
1 and is connected by a cable 40.

The transmission rod 4 which transmits the mechanical displacement of the balance beam 37 to the actuating element 34 in the housing 32 is connected to the balance beam 3.
7, which is formed into a plane including the axis of the outlet hole with an explosion-proof gap 43 between it and the inner wall surface of the outlet hole 42 that penetrates the boundary wall between the driving member case 30 and the housing 32. The tip is inserted into the housing 32 so that it can be freely displaced within the housing 32.
The displacement of the balance beam 37 when the excitation coil 36 is energized is made to face the nozzle 44 inside.
The transmission is transmitted to the actuating element 34 by the swinging of the transmission rod 41 with the supporting plate spring 38 located in the driving member case 30 as a fulcrum, and in this case, the diameter of the transmission rod 41 and the diameter of the outlet hole 42 are By setting the diameter difference between the transmission rod 41 and the transmission rod 41 within the maximum allowable explosion-proof limit, the explosion-proof gap 43 between them
The structure is such that it is within the maximum allowable limit for explosion protection, regardless of the operating position.

A nozzle 44 facing the transmission rod 41 constitutes a nozzle flapper mechanism that works together with the transmission rod 41 to convert displacement into pressure, and is used for nozzle back pressure in an auxiliary plate 45 that serves both for pneumatic piping and for mounting a pilot valve. It is connected to a supply air pressure piping port 47 via a fixed throttle 46, and the back pressure of the nozzle is amplified by a pilot valve 48 attached to an auxiliary plate 45 and guided from an output pressure outlet 49 to an actuator 50. Connected.

A feedback mechanism 51 that feeds back the movement of the actuator 50 has substantially the same configuration as that shown in FIG. 55, there is no need for a pressure-resistant and explosion-proof structure when guiding the shaft 53 and the like from the casing 32 to the outside.

Note that the driving member case 30 and the terminal plate case 31 do not necessarily have to be connected in the illustrated state, and can be overlappingly connected in any direction to reduce the overall size.

In the electro-pneumatic positioner having the above configuration, when the excitation coil 36 is excited, the left end of the balance beam 37 is attracted upward using the supporting plate spring 38 as a fulcrum, so the right end of the transmission rod 41 is displaced downward. to close the nozzle 44.

Therefore, the back pressure of the nozzle 44 increases, the back pressure is amplified by the pilot valve 48 and applied to the actuator 50, and the movement of the actuator 50 is applied by the feedback mechanism 51 to the transmission rod 41 as a force to move it upward, and the balance beam Stop the movement of 37.

Here, the amount of displacement of the transmission rod 41 is small in the portion located inside the outlet hole 42, and the amount of displacement of the transmission rod 41 is small in the portion located within the outlet hole 42, and
It is large in the part facing 4.

Therefore, even if the amount of displacement of the transmission rod 41 in the outlet hole 42 is minute and does not exceed the maximum permissible limit of the explosion-proof gap 43, the necessary and sufficient amount of displacement for the operation of the flapper mechanism can be obtained at the tip. be able to.

Note that the balance beam 37 and the transmission rod 41 do not necessarily need to be supported at a position close to the explosion-proof gap 43 as shown in the figure, but may be supported at the left end of the balance beam or at another intermediate position.

As detailed above, in the present invention, only the electrical drive member is provided in a sealed container with a flameproof explosion-proof structure, and the movement of the drive member is controlled by a transmission rod held in the sealed container through an explosion-proof gap. Since the transmission is configured so that the signal is transmitted to the actuating element, the volume of the airtight container constituting the driving member case is small, making it possible to reduce the overall size and weight.Furthermore, the casing in which the actuating element is installed is flameproof and explosion-proof. There is no need to make a shape, and even in the event of danger, the lid can be opened and the parts installed there can be easily adjusted and repaired.In addition, the transmission rod can be used as a fulcrum to provide the maximum allowable explosion-proof gap. Since it is designed to swing in the diametrical direction of the outlet hole within the limit, an explosion-proof gap is formed between the transfer rod and the outlet hole by minute displacement of the transfer rod within the outlet hole, and a flapper mechanism is installed at the tip of the transfer rod. If the necessary and sufficient displacement amount can be obtained for the operation of the transmission rod, and if the transmission rod is moved in the axial direction within the outlet hole, a plate is installed to prevent the transmission rod from being displaced laterally. The transmission rod must be held in the center of the hole by a spring or the like, and the resistance of the leaf spring greatly affects the operating state. However, in the present invention, there is no need to support the transmission rod by such a leaf spring, and therefore the balance is It has excellent features such as being able to effectively apply the acting force of the beam and feedback mechanism.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional electropneumatic positioner, and FIG. 2 is a sectional view showing an embodiment of the present invention. 32... Housing, 33... Electric drive member, 34...
- Operating element, 36... Exciting coil, 38... Supporting plate spring, 41... Transmission rod, 42... Outlet hole, 43...
・Explosion-proof gap.

Claims (1)

[Claims] 1. In equipment that displaces the balance beam in a torque motor by excitation of an excitation coil and energizes the actuating element by the mechanical displacement, only the electrical drive member such as the excitation coil is fixed in a sealed explosion-proof container. and another mechanical operating element operated by the excitation of the excitation coil is provided in a non-explosion-proof enclosure connected to the sealed explosion-proof enclosure, and the mechanical displacement of the balance beam is transmitted to the operating element within the non-explosion-proof enclosure. A transmission rod is inserted into a lead-out hole provided in a boundary wall between a sealed explosion-proof container and a non-explosion-proof case so that it can be displaced within a plane including the axis of the hole, and the transmission rod is supported within the sealed explosion-proof container. 1. A pressure-resistant explosion-proof construction device, characterized in that the device is swingably supported by a leaf spring, and the difference in diameter between the transmission rod and the outlet hole is set within the maximum allowable explosion-proof limit.