JPH0241892Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is a valve positioner, P (pressure)/I
This invention relates to the structure of an explosion-proof container that houses instruments such as (current) converters and I/P converters.

[Prior Art] As is well known, when devices such as P/I converters and I/P converters are used in an atmosphere of explosive raw gas, the Ministry of Labor's Industrial Safety Regulations require that the containers have a pressure-resistant and explosion-proof structure. These are detailed in the Institute's technical guidelines. In that case, for example, as shown in Japanese Patent Application Laid-Open No. 50-28884, an input signal breather is used to guide the air pressure signal to the P/I converter inside the container, and an atmospheric pressure breather is used to communicate the inside and outside of the container. are provided, each of which has a predetermined clearance depth and clearance based on explosion-proof guidelines. The reason for providing an atmospheric pressure breather is to prevent errors from occurring due to a rise in pressure inside the container due to a rise in external temperature, which would reduce the precision of the instrument if the container is a sealed container.

Figures 3 to 5 show conventional examples of such explosion-proof containers, with Figure 3 being a partially cutaway schematic diagram, Figure 4 being an enlarged sectional view of the input signal arrester section, and Figure 5 being an enlarged sectional view of the input signal arrester section.
The figure is an enlarged sectional view of the atmospheric pressure arrester section. In these figures, an explosion-proof container 1 is formed to have a pressure-resistant explosion-proof structure, and a P/I converter 2 is housed inside, and a flame arrester 3 for input signals and a flame arrester 4 for atmospheric pressure are installed on the wall that partitions the inside and outside. is provided. The P/I converter 2 includes various electrical components 6 and a pressure sensor 7 mounted on a printed circuit board 5, and the pressure sensor 7 is connected to the input signal flame arrester 3 via a pipe 8.

The input signal flame arrester 3 is formed into a cylindrical body with a flange as shown in FIG. A tapered screw hole 11 is formed in the center of the outside surface of the container, and a tapered screw hole 11 is formed in the center of the outside surface. An external pipe 12 for supplying a pneumatic signal P to the pipe 8 is connected via a nipple 13. The flame arrester 3
A columnar fitting 15 is coaxially and loosely fitted into a recess 14 formed on an inner end surface of the recess 14 and communicating with the screw hole 11 , and a flange 15A thereof is fitted into the recess 14 .
It is welded to the open end of 4. Two large and small collars 16 and 17 with different diameters are fitted on the outer peripheral surface of the fitting element 15, and between these two collars 16 and 17,
An annular gap 18 is provided between the fitting element 15 and the collar 16, and between the inner peripheral surface of the recessed part 14 and the collar 17, with a gap depth L and a gap G that meet the explosion-proof guidelines.
A, 18B, and 18C are formed. A large diameter portion 20a and a small diameter portion 20 are provided at the center of the surface of the fitting 15.
A blind hole 20 is formed, and one end of the pipe 8 is connected to the large diameter portion 20a by a piping connection bolt 21. On the other hand, small diameter part 2
A spherical body 22 and a coil spring 23 for press-contacting the spherical body 22 to the inner end surface of the connecting bolt 21 via an O-ring 30 are housed inside 0b. The pipe 8 is pressed against the spherical body 22 against the coil spring 23, thereby separating the spherical body 22 from the O-ring 30, and an axial slit 8A is provided at the tip of the pipe 8. This allows the pipe 8 to communicate with the small diameter portion 20b. The fitting element 15 has a diametrical signal hole 2 communicating with the small diameter portion 20b.
5 is formed through the signal hole 2.
5, insertion holes 26 and 27 are formed in the circumferential surface of each of the collars 16 and 17, respectively.

The air pressure signal P supplied from the external pipe 12 to the screw hole 11 is transmitted to each annular gap 18A, 18B,
18C, through the insertion holes 26, 27, and the signal hole 25 into the small diameter portion 20b, and then through the gap between the sphere 22 and the O-ring 30 and into the pipe 8 through the slit 8A. This air pressure signal P is converted by the pressure sensor 5 of the P/I converter 2 into an electrical signal corresponding to the signal pressure.

The atmospheric pressure flame arrester 4 is loosely fitted into an arrester mounting hole 35 formed through the wall of the explosion-proof container 1, as shown in FIG. 36C is fitted. Between the flame arrester 4 and the inner collar 36A, the collars 36A and 36B
between 36B and 36C and outer collar 36C
A gap depth L and a gap G (not shown) that comply with the explosion-proof guidelines are formed between the inner circumferential surface of the arrester mounting hole 35 and the inner circumferential surface of the arrester mounting hole 35, thereby communicating the inside and outside of the explosion-proof container 1. .

[Problem that the invention attempts to solve]

By the way, such a conventional explosion-proof container 1 is equipped with flame arresters 3 and 4 for input signals and atmospheric pressure, which are manufactured separately, as in the above-mentioned Japanese Patent Application Laid-Open No. 50-28884. However, there were problems in that the number of parts increased, the assembly work was troublesome, the manufacturing cost increased, and the container itself could not be made smaller.

Therefore, the present invention solves the above-mentioned problems and integrates the input signal and atmospheric pressure flame arresters into one, thereby simplifying the structure and reducing the number of parts, resulting in an inexpensive and compact design. The purpose is to provide a safe explosion-proof container.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides a frame with an arrester mounting hole provided in a portion that separates the inside and outside of an explosion-proof container, and a frame having an outer diameter approximately equal to the hole diameter of the arrester mounting hole. The arrester is fitted to form a first annular gap between the arrester mounting hole and the frame arrester with a gap depth and gap that conforms to the explosion-proof guidelines, and a first annular gap is formed inside the frame arrester in the axial direction A through-hole is formed through the through-hole, and a plunger having an outer diameter approximately equal to the diameter of the through-hole is slidably fitted into the through-hole, so that a gap between the through-hole and the plunger conforms to the explosion-proof guidelines. a second annular gap having a depth and gap, and a pipe for guiding a pneumatic signal into the container is connected to the openings at both ends of the through hole, and one end is connected to the arrester mounting hole. An atmospheric pressure bleed hole is formed within the wall thickness of the explosion-proof container so that the first annular gap communicates with the outside of the container by opening at the inner peripheral surface and opening at the other end at the outer surface of the explosion-proof container. It is.

[Effect]

In the present invention, the first annular gap provided between the outer periphery of the flame arrester and the arrester mounting hole acts as an explosion-proof gap for atmospheric pressure, and is provided between the through hole provided in the arrester and the plunger. The second annular gap formed acts as an explosion-proof gap for the input signal.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is an enlarged sectional view of a main part of an explosion-proof container according to the present invention, and FIG. 2 is a side sectional view of the same container. Components and parts that are the same as those in FIGS. 3 to 5 are designated by the same reference numerals, and their explanations will be omitted.
In these figures, arrester mounting holes 50 are formed through appropriate locations on the wall of the explosion-proof container 1, and a cylindrical frame arrester 51 is fitted into this hole 50 via an O-ring 52. And the arrester mounting hole 5 is secured by a plurality of bolts 53.
Fixed to 0. The O-ring 52 is an annular groove 5 provided on the outer peripheral surface of the outer end of the flame arrester 51.
It is attached to 4. The flame arrester 51 has an outer diameter that is approximately the same as the diameter of the arrester mounting hole 50, and has a first annular gap between it and the hole 50 having a gap depth L and a gap G that meet the explosion-proof guidelines. 55 is formed. Further, in the vicinity of the arrester mounting hole 50 within the wall thickness of the explosion-proof container 1, one end is opened to the outside of the container, the other end is opened to the inner peripheral surface of the arrester mounting hole 50, and the first Atmospheric pressure bleed hole 56 communicating with the annular gap 55 of
is formed, whereby the first annular gap 55 forms an explosion-proof gap for atmospheric pressure.

A through hole 57 with partially different hole diameters is opened in the axial direction in the center of the interior of the frame arrester 51, so that both ends thereof are opened at both end surfaces of the arrester 51, and the outer opening end is tapered. A threaded hole 11 is provided, and an external pipe 12 is connected via a nipple 13. On the other hand, one end of the pipe 8 is connected to the P/I converter 2, and the other end of the pipe 8 is connected to the inner open end via a piping connection bolt 21. In the center of the through hole 57,
A plunger 58 having a diameter substantially equal to the diameter of the hole in the central portion, and a coil spring 23 that presses the plunger 58 against the inner end surface of the piping connection bolt 21 via an empty ring 59 and an O-ring 60 are housed. . A second annular gap 61 having a gap depth L ₁ and a gap G ₁ applicable to the explosion-proof guideline is formed between the inner circumferential surface of the center portion of the through hole 57 and the plunger 58, and this is the input gap. It forms an explosion-proof gap for signals.

That is, in the present invention, by forming explosion-proof gaps for input signals and atmospheric pressure inside and outside of one flame arrester 51, one arrester can be used for input signals instead of the conventional two flame arresters. It is designed for atmospheric pressure.
Therefore, the number of parts can be reduced, the number of assembly steps can be saved, and the explosion-proof container 1 itself can be simplified and downsized.

Although the above embodiment used a flame arrester 51 made of one cylindrical body, the present invention is not limited to this in any way, and the present invention is not limited to this in any way.
Of course, as shown in the figure, the flame arrester may be configured with a plurality of collars that have different diameters and that fit together.

[Effect of idea]

As explained above, according to the structure of the explosion-proof container according to the present invention, the two annular gaps provided inside and outside of the flame arrester function as explosion-proof gaps for input signals and for drawing atmospheric pressure. This eliminates the need to provide separate flame arresters for input signals and atmospheric pressure as in the past, reducing the number of parts and man-hours required to install the flame arrester, making it possible to reduce costs and downsize. .

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts showing the structure of the explosion-proof container according to the present invention, Fig. 2 is a side sectional view of the same container, and Figs.
Fig. 5 shows an example of a conventional explosion-proof container, Fig. 3 is a side sectional view of the same container, Fig. 4 is an enlarged sectional view of the input signal arrester section, and Fig. 5 is an enlarged sectional view of the atmospheric pressure arrester section. It is a diagram. 1...Explosion-proof container, 2...P/I converter, 8,1
2...Pipe, 50...Arrester mounting hole, 51
...Flame arrester, 52...O ring, 55
...First annular gap, 56...Atmospheric pressure bleed hole, 57...Through hole, 58...Plunger, 6
1...Second annular void.

Claims (1)

[Scope of utility model registration request] An arrester mounting hole is provided in a portion that separates the inside and outside of the explosion-proof container, and a frame arrester having an outer diameter approximately equal to the hole diameter of the mounting hole is fitted into the arrester mounting hole. forming a first annular gap between the hole and the flame arrester with a gap depth and gap that conform to explosion-proof guidelines, and opening a through hole penetrating inside the flame arrester in its axial direction; A plunger having an outer diameter approximately equal to the hole diameter of the through hole is slidably fitted into the through hole to provide a clearance between the through hole and the plunger that meets explosion-proof guidelines. A second annular gap is provided, and pipes for guiding air pressure signals into the container are connected to the openings at both ends of the through hole, and one end opens to the inner circumferential surface of the arrester mounting hole and the other end opens to the inner peripheral surface of the arrester mounting hole. A structure of an explosion-proof container, characterized in that an atmospheric pressure bleed hole is formed within the wall thickness of the explosion-proof container to communicate the first annular gap with the outside of the container by opening on the outer surface of the explosion-proof container.