JP3148884B2 - On-site instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure / pressure transmitter which is installed on site and detects the pressure of various process fluids, etc.
The present invention relates to a field-type instrument suitable for application to an electromagnetic flow meter or the like.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a conventional example of a standard type differential pressure / pressure transmitter known as a kind of a field type instrument.
This differential pressure / pressure transmitter 1 is a body body (instrument body)
2, an electric device case 3 provided integrally with the body 2 and a meter case 4 provided integrally with one side of the electric device case 3. The body main body 2 applies each process fluid pressure to the high-pressure side and low-pressure side barrier diaphragm chambers (not shown), and guides the pressure due to the sealing liquid in the body main body 2 to a semiconductor pressure sensor provided so as to partition an enclosed circuit. It is configured to convert the distortion into an electric signal and take it out (eg, Japanese Utility Model Publication No. 59-30444). A terminal block 5 is provided inside the electrical device case 3, and a terminal 6 provided at the center of the front surface of the terminal block 5 is provided with a connection provided at one end of a cable 7 for performing signal transmission and power supply to an external device. The terminal 8 is fixed by a set screw 9. In addition, the front opening of the electrical device case 3 forms a terminal connection opening for connecting the connection terminal 8 to the terminal 6, and the opening is hermetically closed by the lid 10. An insertion hole 11 through which the cable 7 is inserted is provided on a side surface opposite to the meter case 4. The meter case 4 is provided separately from the electric device case 3 in order to satisfy the explosion-proof standard. The meter case 4 accommodates a meter 12 for displaying a differential pressure therein, and a front opening is hermetically closed by a cover 13. The cover 13 has a transparent glass 14 so that the display of the meter 12 can be visually recognized from the outside.

On the other hand, when it is not necessary to meet the explosion-proof standard, a device in which a terminal and a meter are incorporated in one housing to reduce the size and weight of the entire device is known. In this non-explosion-proof differential pressure / pressure transmitter, a meter is integrally incorporated inside a cover that covers a front opening of a housing.

[0004]

In a differential pressure / pressure transmitter that satisfies the above explosion-proof standard, it is prohibited to place a shield in front of the terminal. 4 had to be provided separately, but with such a structure, there were problems that the size and weight could not be reduced, the number of parts and the number of assembly steps increased, and the manufacturing cost increased.

On the other hand, in a non-explosion-proof differential pressure / pressure transmitter incorporating a terminal and a meter in one housing,
Because the meter is integrated into the cover, SFC
When performing zero adjustment, span adjustment, etc. called (smart field communicator), if the cover is removed, the meter will come out integrally with the cover, so the display contents of the meter cannot be checked during adjustment, For this reason, there is a trouble that a digital voltmeter or the like must be connected and adjustment is performed while checking the displayed contents. Also,
Conventionally, the cable is connected to the terminal and the extra length is pushed into the housing, so the terminal is hidden by the extra length, or the screw part bites into the extra length when screwing the cover to the housing. There is a problem that the extra length portion is caught between the terminal and the meter, but no special countermeasure has been taken against this problem. Usually, when a user lays out a cable, the cable is cut for a long time and the connection is made, so that the above-described problem occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to reduce the size and weight while satisfying the explosion-proof requirements and to store the cable well. It is an object of the present invention to provide a field-type instrument capable of performing an adjustment operation while observing the displayed contents of a meter when performing an adjustment operation such as a zero adjustment and a span adjustment.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a housing integrally provided with an instrument body having a terminal connection opening on the front surface, and a front end projecting forward at the center of the front surface. A terminal block integrally having a cylindrical meter storage section provided with an opening on the surface and fixed in the housing; and a terminal provided on the front of the terminal block to which a cable for connecting to an external device is attached. A meter incorporated in a meter storage portion of the terminal block, and a cover having a window through which a display of the meter is visible from the outside and closing the terminal connection opening of the housing. Features. Further, the present invention is characterized in that at least a part of the periphery of the meter storage portion is a cable storage space.

According to the present invention, since the meter is disposed in the meter storage portion of the terminal block and the terminal is disposed around the terminal block, the meter does not become a shield against the terminal and satisfies the explosion-proof standard. Then, the meter and the terminal can be stored in one housing. The space between the meter housing and the inner peripheral surface of the housing forms a cable housing space.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a partially cutaway side view showing an embodiment in which the present invention is applied to a differential pressure / pressure transmitter, FIG. 2 is a front view of a housing, and FIG. FIG. Note that the same components as those described in the section of the related art are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In these drawings, the differential pressure / pressure transmitter 1 includes a body 2 and a housing 20 provided integrally with the neck 2a of the body 2.

The housing 20 is formed in a cylindrical body whose front and rear surfaces are open, and a front end side opening thereof forms a terminal connection opening 22 for connecting the cable 7 to the terminal 6. The terminal connection opening 22 is airtightly closed by screwing the cover 23 through the O-ring 24. The cover 23 has an opening 23a airtightly covered by the transparent glass 14, and
The window part which enables the visual recognition of is formed. On the other hand, the rear end side opening 25 of the housing 20 has O
It is screwed through a ring 26 and fixed by a plurality of bolts 27. The housing 20
On the side of the housing 20, two insertion holes 11 into which the cable 7 for performing signal transmission and power supply to an external device is inserted are positioned vertically above and below the center of the housing 20 and point-symmetrically. Is formed. The terminal block 5 is fixed inside the housing 20 by a plurality of set screws 28. The terminal block 5 is integrally formed of an insulating material such as a synthetic resin, and has a main body 5A provided with a plurality of terminals 6;
At the center of the front surface of the main body 5A, there is provided a cylindrical meter housing portion 5B integrally protruding forward, and a terminal block mounting portion provided on the inner peripheral surface of the housing 20 by the set screw 28 on the outer peripheral portion of the main body 5A. It is fixed to the unit 30. The terminal 6 is positioned above and below the meter housing 5B.
Two are provided on the upper and lower portions of A, and the rear ends extend behind the terminal block 5 and are connected to the electric circuit of the printed circuit board 31. The printed circuit board 31 is fixed to the rear opening of the terminal block 5. The meter storage section 5B is formed in a horizontally long cylindrical body, and has an opening 33 on the front surface thereof.
The meter 12 is disposed in the meter storage unit 5B so as to cover the meter 3. The printed board 34 of the meter 12 and the printed board 31 are electrically connected by a lead wire 35. The two insertion holes 11 are formed such that their axes are substantially parallel to the longitudinal direction of the meter housing 5B.

The cable 7 is inserted into the housing 20 through each of the insertion holes 11, and connection terminals 8 fixed to the insertion ends thereof are connected to the respective terminals 6 by set screws 9. At the front side of the terminal block 5, the meter storage section 5B
An appropriate space is formed between the cable and the inner peripheral surface of the housing 20, and this space forms a storage space 40 for storing the extra-length portion 7A of the cable 7.

In the differential pressure / pressure transmitter 1 having such a structure, the meter 12 is arranged at the center of the inside of the housing 20, and the terminal 6 is arranged behind and above and below the meter 12. Therefore, the meter 12 does not become an obstacle to the terminal 6 and can be used as a differential pressure / pressure transmitter satisfying the explosion-proof regulations. Further, since the meter 12 is disposed in the housing 20, connection of the cable 7 and
Even if the cover 23 is removed during adjustment work such as zero adjustment and span adjustment, the meter 12 does not come out together with the cover 23, and the adjustment work can be performed while looking at the display contents of the meter 12.

Since the space around the meter housing 5B is a housing space 40 for the cable 7, the housing 20
Can be effectively used. In particular, when the extra length portion 7A is too long, it can be wound around and stored in the meter storage portion 5B, and the storage of the cable 7 is easy. Further, as shown in FIG. 3, two insertion holes 11 are formed vertically and point-symmetrically with respect to the center of the housing 20, and the upper insertion hole 1 is formed.
The cable 7 inserted from 1 is curved clockwise along the inner peripheral surface of the housing 20 and connected to the lower terminal 6,
When the cable 7 inserted from the lower insertion hole 11 is similarly curved clockwise along the inner peripheral surface of the housing 20 and connected to the upper terminal 6, an external force in the axial direction is applied to the cable 7. Even so, since the terminal connection portion is caught on the corner portion of the meter storage portion 5B, a large stress is not applied to the terminal connection portion, and disconnection of the cable 7 at the connection portion can be prevented.

FIG. 4 is a partially cutaway front view showing a housing according to another embodiment of the present invention. In this embodiment, the left and right insertion holes 11 are formed at symmetrical positions on both sides of the housing 20 so that their axes are aligned with each other so as to pass through the center of the housing 20, and the four corners of the meter housing 5B are formed. Among them, the protruding portions 45 are respectively protruded from two corner portions located on one of the diagonal lines, and are formed in a substantially rhombic shape when viewed from the front. Other configurations are the same as those of the above-described embodiment.

In such a structure, the gap between the convex portion 45 of the meter housing 5B and the inner peripheral surface of the housing 20 is smaller than the gap between the corner where the convex portion is not formed and the housing. In addition, since it is difficult to route the cable 7, it is possible to reliably prevent erroneous connection of the cable 7 to the terminal.

Although the present invention has been described with reference to an example of a differential pressure / pressure transmitter as a field-type instrument, the present invention is not limited to this, and may be applied to an electromagnetic flow meter or the like.

[0017]

As described above, the field-type instrument according to the present invention has a housing integrally provided in the instrument body with a terminal connection opening on the front face, and a front end projecting forward at the center of the front face. A terminal block integrally having a cylindrical meter housing portion provided with an opening on the surface and fixed in the housing,
It has a terminal provided on the front surface of the terminal block, to which a cable for connecting to an external device is attached, a meter incorporated in a meter storage section of the terminal block, and a window through which a display of the meter can be visually recognized from outside. Since the housing is configured with a cover that closes the terminal connection opening, the meter does not become an obstacle to the terminal, and it is possible to reduce the size, weight, and cost while meeting explosion-proof requirements.
Further, even if the cover is removed, the meter does not come out together with the cover, so that it is possible to perform an adjustment operation while observing the display contents of the meter at the time of adjustment operation such as zero adjustment and span adjustment. Further, since at least a part of the periphery of the meter storage portion is used as a cable storage space, cable storage is easy.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing an embodiment in which the present invention is applied to a differential pressure / pressure transmitter.

FIG. 2 is a sectional view of a housing with a cover removed.

FIG. 3 is a front view of the housing with a cover removed.

FIG. 4 is a partially cutaway front view showing a housing according to another embodiment of the present invention.

FIG. 5 is a partially broken plan view showing a conventional example of a differential pressure / pressure transmitter.

FIG. 6 is a front view of the transmitter with a cover removed.

[Explanation of symbols]

1 ... Differential pressure / pressure transmitter, 2 ... Body body (instrument body),
3 ... Electrical equipment case, 4 ... Meter case, 5 ... Terminal block,
5A: Main body, 5B: Meter storage section, 6: Terminal, 7: Cable, 8: Connection terminal, 11: Insertion hole, 12: Meter, 1
4 ... Transparent glass, 20 ... Housing, 22 ... Opening for terminal connection, 23 ... Cover, 33 ... Opening, 40 ... Storage space.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01D 11/24 G01L 13/00 G01L 19/14

Claims (2)

(57) [Claims] 1. A housing having an opening for terminal connection on the front surface and integrally provided in an instrument main body, and a cylindrical meter housing portion having a front end protruding forward at the center of the front surface and having an opening at the tip end surface. A terminal block integrally fixed in the housing, a terminal provided on a front surface of the terminal block, to which a cable for connecting to an external device is attached, and a meter incorporated in a meter storage portion of the terminal block. And a cover that has a window through which the display of the meter can be visually recognized from the outside and closes the terminal connection opening of the housing. 2. The field-type instrument according to claim 1, wherein at least a part of the periphery of the meter storage portion is a cable storage space.