JP2799083B2 - Pressure / differential pressure transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure / differential pressure transmitter for measuring the pressure / differential pressure or liquid level of various process fluids and transmitting the measurement signal.

[0003]

2. Description of the Related Art A pressure / differential pressure transmitter of this type has a built-in pressure sensor for outputting a pressure received by a seal diaphragm as an electric detection signal, and a cylinder for deriving a detection signal line from the pressure sensor. A detection unit body having a protruding connection portion protruding from one side is connected to the detection unit body via the cylindrical connection portion, and a detection signal line via the connection portion is connected to calculate a detection signal. Generally, there is a configuration including an amplifier housing chamber housing an amplifier unit for processing and transmitting to the outside, and a transmission unit housing consisting of a terminal box integrally housed on one side thereof and housing a terminal block. It is.

[0004]

Conventionally, as shown in FIG. 3, a cylindrical connecting portion 9 protruding from the detecting portion body is provided on the transmitting portion housing 1 to connect the detecting portion body to the transmitting portion housing. The fixing screw 4 is screwed into the cylindrical connecting portion 9 in the vicinity of the end of the cylindrical connecting portion 3 and fixed. However, since the fixing screw 4 is arranged outside the transmission unit housing 1 and is exposed to the atmosphere in which the transmitter is installed, corrosion resistance is required. In addition, since the O-ring 5 for isolating the inside of the transmission unit housing 1 from moisture, corrosive gas, and the like also needs to be disposed inward of the fixing screw 4, the O-ring 5 is located at the end of the cylindrical coupling unit 3 The inner surface up to the O-ring 5 is exposed to the outside atmosphere.

Usually, the detection unit body is made of stainless steel, and the transmission unit housing 1 is often made of aluminum alloy, and the inner surface of the cylindrical coupling unit 3 is not painted.
The inner surface from the end of the cylindrical coupling portion 3 to the O-ring 5 and the insertion hole of the fixing screw 4 are corroded in places where the atmospheric conditions are poor. As the corrosion progresses, the groove of the O-ring 5 is also corroded, and outside air may enter the inside of the transmission unit housing 1 in some cases.

In order to solve this drawback, as shown in FIG. 4, a cylindrical coupling portion 3 is provided so as to protrude into the amplifier housing chamber 2 of the transmission unit housing 1 and is slightly inserted from the open end on the outer surface of the housing. In some cases, an O-ring 5 is provided on the inner surface and the fixing screw 4 is arranged near the inner end of the cylindrical coupling portion 3 protruding into the housing. However, it is extremely difficult to insert and tighten the fixing screw 4 into the insertion hole in the amplifier housing 2, and it is impossible depending on the size of the amplifier housing 2.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure / differential pressure transmitter having a structure of a detecting unit body and a transmitting unit housing which can solve the above-mentioned drawbacks, and a structure of a part connecting both of them. .

[Structure of the Invention]

[0009]

According to the pressure / differential pressure transmitter of the present invention, the wall of the transmission unit housing, which is formed in the terminal box, has a cylindrical shape in which the cylindrical connecting portion is fitted. The connecting portion forms a part of a wall formed by protruding into the housing. An O-ring is disposed on the inner surface of the cylinder near the entrance of the outer surface of the housing of the cylindrical connecting portion. The terminal box is provided with an opening so that it can be hermetically sealed by a lid, and the cylindrical connecting portion fitted inside the cylindrical connecting portion is fixed by a fixing screw provided on the wall at the end of the terminal box. And

[0010]

In the pressure / differential pressure transmitter according to the present invention, the cylindrical coupling portion projects into the transmission portion housing, and the O-ring is disposed on the inner surface of the cylinder near the entrance of the outer surface of the housing of the coupling portion. On the other hand, the inside is shielded from the outside air, so that corrosion of an unpainted portion in the housing can be prevented. In addition, since the fixing screws for fixing the cylindrical coupling portion of the detection unit body fitted inside the cylindrical coupling portion are arranged inside the terminal box sealed with the lid, the screws are exposed to the outside air. Corrosion is prevented. Further, since the fixing screws are provided on the front end wall when viewed from the opening of the terminal box, operations such as mounting, tightening or removing the screws are easy.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIG. 1 shows a pressure / differential pressure transmitter according to an embodiment of the present invention. In FIG. 1, the pressure / differential pressure transmitter has a built-in pressure sensor (not shown) which transmits the pressure received by the seal diaphragm 7 through the sealed liquid and outputs it as an electrical detection signal. A cylindrical connecting portion 9 for deriving a detection signal line or the like (not shown) is connected to the detecting portion body 6 protruding from one side and connected to the detecting portion body 6 via the cylindrical connecting portion 9. A detection signal line connected via the connecting portion 9 is connected to an amplifier storage chamber 12 for storing an amplifier unit for processing and transmitting the detection signal to the outside, and a terminal block integrally connected to one side thereof. And a transmission unit housing 11 composed of a terminal box 13 accommodating therein. Reference numeral 8 in the figure denotes a cover flange integrally provided on both sides of the detection unit body 6 and for applying a measurement pressure to the seal diaphragm 7.

The structure of the transmission section housing 11 is such that a cylindrical coupling section 16 for internally fitting the cylindrical coupling section 9 of the detection section body 6 is formed to protrude into the transmission section housing 11 to form a terminal box 13. The wall 14 at the rear end of the connecting wall forms a part of the wall of the cylindrical coupling portion 16.
The O-ring 5 is disposed on the inner surface of the cylindrical portion 16 near the entrance of the outer surface of the housing. Further, an opening of the terminal box 13 is provided at a position directly opposite to the end wall 14 forming a part of the wall of the cylindrical coupling portion 16, and can be sealed by the lid 15. A convex portion 17 is formed on the wall at the end of the terminal box 13. A fixing screw 4 is screwed into a screw hole provided in the convex portion, and a concave portion provided in the fitted cylindrical connecting portion 9. The transmission section housing 11 and the detection section body 6 are fixed by engaging the tip of the screw 4 with 10.

In the pressure / differential pressure transmitter according to one embodiment of the present invention, the cylindrical connecting portion 16 projects into the transmitting portion housing 11, and the outer surface of the cylindrical connecting portion 16 is provided outside the housing. Since the O-ring 5 is arranged on the inner surface of the cylinder near the entrance, the inside of the O-ring 5 is shut off from the outside air, so that the unpainted portion in the transmission unit housing 11 such as the inner surface of the cylinder is exposed to the outside air and corrosion is prevented. Is prevented. Further, since the fixing screw 4 for fixing the cylindrical connecting portion 9 of the detecting portion body 6 fitted inside the cylindrical connecting portion 16 is disposed inside the terminal box 13 sealed with the lid 15. The screw and the screw hole are not exposed to the outside air, corrosion is prevented, and the outside air is prevented from entering the inside of the transmission unit housing 11.
Further, since the fixing screw 4 is provided on the wall 14 at the front end when viewed from the opening of the terminal box 13, the operation of mounting, tightening or removing the screw is easy. Therefore, it is not necessary to increase the size of the amplifier housing chamber for the screw operation as in the prior art, and the entire amplifier housing chamber 12 and the transmission unit housing 11 can be reduced in size.

As shown in FIG. 2, an insertion hole 18 for inserting the lower part of the neck of the fixing screw 4 into the wall 14 at the end of the terminal box 13 and a screw hole 19 in the cylindrical connecting portion 9 are provided. Alternatively, the fixing screw 4 may be screwed into the screw hole 19 through the insertion hole 18 to fix the transmission unit housing 11 and the detection unit body 6.

[0016]

As described above in detail, according to the present invention, the end of the wall forming the terminal box of the transmission housing has the cylindrical connecting portion for fitting the cylindrical connecting portion inside the housing. An O-ring is disposed on the inner surface of the cylinder near the entrance of the outer surface of the housing of the cylindrical coupling portion, and an opening of the terminal box is provided at a position directly opposite the end wall. The terminal box can be hermetically sealed, and a fixing screw provided on a wall at the end of the terminal box is used to fix the cylindrical connecting portion internally fitted in the cylindrical connecting portion. As a result of the realization of the pressure transmitter, the O
The ring prevents the unpainted portion inside from the outside air from being corroded. Further, since the fixing screw is disposed inside the terminal box sealed with the lid, the screw portion is not exposed to the outside air, and there is no danger of corrosion. Further, since the fixing screw is provided on the wall at the end of the front as viewed from the opening of the terminal box, the mounting of the screw,
Operation such as tightening or removing is easy. Therefore, it is not necessary to provide a space for screw operation inside, and the transmission unit housing can be downsized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a pressure / differential pressure transmitter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a connecting portion between a transmission unit housing and a detection unit body of a pressure / differential pressure transmitter according to a modification of the present invention.

FIG. 3 is a cross-sectional view showing a connection portion between a transmission unit housing and a detection unit body of a conventional pressure / differential pressure transmitter.

FIG. 4 is a cross-sectional view showing another example of a connection portion between a transmission unit housing and a detection unit body of a conventional pressure / differential pressure transmitter.

[Explanation of symbols]

 4. Fixing screw 5. O-ring 6. Detector body 9. Cylindrical connecting part 10. Concave part 11. Transmitter housing 12. Amplifier storage room 13. Terminal box 14. End wall 15 ... Lid 16 ... Cylindrical connection Part 17: Convex part 18: Insertion hole 19: Screw hole

Claims (1)

(57) [Claims] 1. A cylindrical connecting portion which has a built-in pressure sensor for transmitting a pressure received by a seal diaphragm through an enclosed liquid and outputting it as an electric detection signal, and leading out a detection signal line and the like from the pressure sensor. Is connected to the detection unit body protruding from one side part via the cylindrical connection unit, and a detection signal line via the connection unit is connected to perform arithmetic processing of the detection signal and perform external processing. A pressure / differential pressure transmitter comprising an amplifier housing chamber housing an amplifier unit for transmitting data to the transmitter and a transmission unit housing consisting of a terminal box integrally housed on one side thereof and housing a terminal block. The rear wall of the wall forming the terminal box of the transmission housing forms a part of a wall formed by projecting a cylindrical coupling portion for fitting the cylindrical coupling portion into the housing. Like An O-ring is arranged on the inner surface of the cylinder near the entrance of the outer surface of the housing of the cylindrical coupling portion, and an opening of the terminal box is provided at a position directly opposite to the end of the end wall so that the terminal box can be hermetically sealed by a lid. A pressure / differential pressure transmitter, wherein a cylindrical connecting portion internally fitted in the cylindrical connecting portion is fixed by a fixing screw provided on a wall.