JPS60108724A - Differential pressure and pressure transmitter - Google Patents

Abstract

PURPOSE:To make it possible to perform ideal correction of temperature characteristics and to improve measuring accuracy, by providing two overload protecting means on the high pressure side and the low pressure side in the bypass of the through hole of a circular cylinder block. CONSTITUTION:A circular cylinder block 5 is inserted and fixed in an inner hole 2c of a main part 2b of a body. A pressure sensor 12 is arranged so as to block one end of a central through hole 5b of the circular cylinder block 5. The sensor 12 is connected to the conductive member in a recess part 5c in the outer surface of the circular cylinder block 5 by a seal terminal 16. Pressure receiving diaphragms 22 and 24 are fixed to back plates 6 and 7, which are fixed to both end surfaces of the circular cylinder block 5, respectively. Overload protecting devices 32 and 33 are provided in the bypass of the through hole 5b of the circular through hole 5. Thus the entire measuring instrument can be made compact, operation is made easy, and the measuring instrument can be improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a pressure transmitter that compares atmospheric pressure or vacuum pressure with a process pressure and transmits the signal, and a pressure transmitter that compares the process pressure with another process pressure and transmits the signal. This relates to pressure/differential pressure transmitters, which collectively refer to differential pressure transmitters.

[Prior art]

In general, a pressure transmitter or a differential pressure transmitter has diaphragms airtightly installed at both ends of the internal chamber of the body, and the reference pressure or measured pressure applied from the outside to these diaphragms is transmitted via the liquid sealed in the internal chamber of the body. The pressure is transmitted to the pressure sensor in the sensor chamber, and the pressure sensor converts the differential pressure into an electrical quantity and transmits it.

However, in conventional pressure/differential pressure transmitters, the pressure sensor is located far from the diaphragm.
The passage connecting them has become longer, the passage volume within the body interior has increased, and the amount of sealed liquid has also increased. As a result, when the environmental temperature of the instrument rises, the amount of expansion of the filled liquid is large, and the pressure due to this expansion acts on the inside of the diaphragm and reaches a non-negligible amount, allowing the diaphragm to accurately measure the measured pressure. There was a problem that it could not be detected. Particularly, in the case where a pressure bypass is provided and an overload protection means is built in in the middle thereof, the amount of sealed liquid becomes large, and this problem becomes even more serious.

To solve this problem, the diameter of the diaphragm is increased to increase the pressure-receiving area and reduce the effect of the expansion of the sealed liquid. However, it is not only difficult to handle, but also increases the cost of materials, making it economically unfavorable.

In addition, this type of differential pressure/pressure transmitter is often equipped with a resistance temperature detector as a detection means to ensure that the characteristics of the pressure sensor are not affected by temperature changes. For this purpose, it is common to install this resistor on a relay board near the pressure sensor, but if you are aiming for higher compensation, consider the effect of temperature changes on the diaphragm or sealed fluid on the pressure sensor. Must-have. In this case, if the difference between the measured temperature and the temperature in the pressure receiving chamber is large, the respective correction characteristics will not be proportional to each other, which is not preferable as a correction form.

[Summary of the invention]

The present invention has been made in view of the above points, and a pressure sensor is disposed to close one end of the center through hole of a cylindrical block inserted and fixed in the inner hole of the body, thereby preventing the slippage and the inside of the four circumferential parts of the cylindrical block. By connecting the conductive member with a seal terminal, fixing the pressure receiving diaphragm to a back plate fixed to both end faces of the cylindrical block, and providing an overload protection means in the through-hole bypass of the cylindrical block, Bringing the pressure sensor and diaphragm close together,
It is possible to reduce the volume of the internal chamber of the body, reduce the influence of internal pressure on the diaphragm, improve measurement accuracy, and place a resistor for temperature correction close to the pressure receiving chamber. The present invention provides a pressure/differential pressure transmitter that makes it possible to correct ideal temperature characteristics in which there is little temperature difference between the pressure chamber and the inside of the pressure receiving chamber. Embodiments of the present invention will be described in detail below with reference to the drawings.

〔Example〕

1 to 3 show an embodiment of the pressure/differential pressure transmitter according to the present invention, FIG. 1 is a longitudinal cross-sectional view thereof, and FIG. 2 is a cross section AA of FIG. FIG. 3 is a BB sectional view of FIG. 2. In these figures, a cylindrical connecting pipe 2a,
On the other hand, the body 2 is integrally formed with a flat cylindrical body 2b whose axes are perpendicular to each other. The pressure receiving unit shown is the back plate 6 described later.
．． 7 turns are fitted and fixed airtight. The pressure receiving unit 4 is integrally formed with a cylindrical block 5 having a smaller diameter than the body inner hole 2c and a disc-shaped back plate 6.7 hermetically fixed to both end surfaces of the cylindrical block 5. , each back plate 6.7 has a process cover 9 with a low pressure inlet 8 connected to the low pressure side of the process;
A process cover 11 provided with a high pressure inlet 10 connected to the high pressure side of the process is hermetically fixed.

A rectangular recess 5 is provided on the high pressure side end surface of the cylindrical block 5.
A is formed in the center of the cylindrical block 5, and a through hole is formed in the center of the cylindrical block 5, passing through between the end face on the low pressure side and the bottom face of the recessed part 5a, and having a small diameter on the low pressure side as well as on the high pressure side. A hole 5b is bored. The reference numeral 12 is a rectangular plate-shaped pressure sensor made of a silicon diaphragm that acts as a pressure-to-electricity conversion element, and this pressure sensor 12 is a cylindrical sensor made of glass having the same expansion coefficient as that of the pressure sensor 12. The sensor holder 13 is joined to the non-fixed side end face of the holder 13 and fixed in an airtight manner, and the sensor holder 13 is fitted in the small diameter portion on the low pressure side of the through hole 5b and fixed in an airtight manner. Note that since the cylindrical block 5 is made of metal such as Fernico alloy (54Fe, 28N1.18Co) having an expansion coefficient similar to that of glass, the senna holder 13 can be bonded well.

14 is a relay board made of a printed board formed into a rectangular plate shape, covered with a protective cover 15 whose front and back sides are communicated with each other through a communication hole 15&, and inserted into a recessed part 5a. In order to create a gap between the pressure sensor 12 and the pressure sensor 12, a large rectangular hole is bored in the section, and the periphery of the rectangular hole of the pressure sensor 12 and the relay board They are connected by a thin wire 12a. Furthermore, a pair of half-moon-shaped recesses 5c facing each other are formed on the outer circumferential surface of the cylindrical block 5, and eight recesses are bored through the space between the recesses 5c and the recesses 5a. In each of the through-holes, a seal terminal 16 made of Pyrex or the like is fitted and fixed in the through-hole, and one end of the seal terminal 16 is connected to a printed wiring of a flexible printed board 19 (described later) with one end facing into the recess 5C. . . . are insulated by mesh seals 17 and inserted into each other. The pressure sensor 12 and the flexible printed board 19 are electrically connected by connecting the insertion end of each seal terminal 16 and each of the thin gold wires 12a with another thin gold wire 1a. .

The flexible printed board 19 is formed by bending a thin plate into a zigzag shape and extends inside the connecting pipe 2& toward the electrical surface 1, and one end of the flexible printed board 19 is inserted into the recess scK of the cylindrical block 5 as described above. Each printed wiring printed on this is connected to each seal terminal 16, and the other end of the printed wiring is connected to the connector 2o at the end of the connecting tube 2a.
Processing is connected.

On the other hand, the low-pressure side back plate 6 has a communication hole 21 in the center that communicates the front and back sides thereof, and a diaphragm formed in the shape of a circular corrugated plate on the outer surface of the back plate 6. 22 is airtightly fixed at its peripheral edge, and a pressure chamber 9a is formed outside of the pressure chamber 9a, into which the low pressure introduction hole 8 opens.

Furthermore, the high-pressure side back plates 1 and 7 are provided with a communication hole 23 in the center that communicates the front and back surfaces thereof, and a circular corrugated plate is formed on the outer surface of the back plate 1. A diaphragm 24 is airtightly fixed around the periphery, and an isobaric chamber 11 has the high pressure introduction hole 10 opened outside the diaphragm 24.
a is formed.

The space 25 between the cylindrical block 5 and the low-pressure side back plate 6 and the recessed portion 5m communicate with each other through a bellows hole 26.27 and a passage 28.29, which serve as a pair of bypasses for the through hole 5b. For each bellows hole 26
, 27 are closed by seat plates 30, 31 having communication holes, and the opening ends of each of the pez holes 26, 27 are closed by seat plates 30, 31 having communication holes.
Overload protection means 32, 33 are loaded inside, respectively. Among these, the overload protection means 32 on the high pressure side is composed of a bellows 34 whose inside is communicated with the concave portion 5&, and a spring 35 that biases the bellows 34 in the direction of contracting via the flange of the shaft. In addition, the overload protection means 33 on the low pressure side includes a bellows 36 whose interior is communicated with the space 25.
and a spring 37 that biases the bellows 36 of the shaft in the direction of contracting through the collar of the shaft.

In the pressure receiving unit 4 configured as above, the cylindrical block 5, the back plate T1 diaphragm 24, the pressure sensor 12, the sensor boulder 13, the hermetic seal 17, the bellows 34, the protective cover 15, the relay board 14
A pressure receiving chamber on the high pressure side is constituted by an airtight space formed by . A sealed liquid such as silicone oil is sealed in the pressure receiving chamber of . The sealing pressure of the sealing liquid causes the diaphragm 24 to separate from the outer surface of the pack plate 1, and a gap is formed therebetween. In addition, a pressure receiving chamber on the low pressure side is constituted by an airtight space formed by the cylindrical block 5, bank plate 6, diaphragm 22, pressure sensor 12, sensor bolt 13, and bellows 36, and a liquid such as silicone oil is filled in the pressure receiving chamber. is included. The pressure of this filled liquid causes the diaphragm 22 to move toward the pack plate 6.
away from the outer surface, and a gap is formed between them.

Furthermore, within the recess 5c of the cylindrical block 5, a differential pressure
A resistor 38 for correcting the temperature characteristics of the pressure transmitter is
It is connected to the flexible printed board 19 and arranged.

The operation of the differential pressure transmitter configured as above will be explained. Process pressure Ps introduced through high pressure introduction hole 1o
is applied to the surface of the diaphragm 24, this pressure passes through the communication hole 23.15m and the sealed liquid to the pressure sensor 12.
transmitted to the surface of

On the other hand, when the process pressure P2 introduced from the low pressure introduction hole 8 is applied to the surface of the diaphragm 22, this pressure passes through the communication hole 21 and the sensor holder 13, that is, the through hole 5b, and the pressure sensor 12 through the sealed liquid. Since the pressure is transmitted to the back surface, the pressure sensor 12 has a differential pressure between both pressures (PI-P2)/i
It receives a strain corresponding to n, and this strain is converted into an electrical quantity. Then, an electrical signal corresponding to the value of the differential pressure is guided to the connector 20 via the thin gold wire 12a1, the relay board 14, the gold side 1i 118, the seal terminal 16, and the flexible printed board 19.
The information is transmitted from here to a control device (not shown).

In this case, the pressure applied to the diaphragm 24 is simultaneously transmitted to the bellows hole 26, which is a bypass, and pressure is generated inside the bellows 34.

As a result, the bellows 34 tries to be displaced in the direction of extension, but if this pressure is less than the set pressure, the spring 34
The bellows 34 does not move because it cannot overcome the force of the 50 shot. The pressure in this case is set so that the bellows 34 will not be displaced even if the maximum pressure that can be measured by the pressure sensor 12 is applied to the bellows 34, and the sealed liquid will hardly move within this pressure range. When an excessive pressure exceeding the measurement pressure range is applied to the diaphragm 24, the spring 35 is unable to resist this pressure and is compressed, causing the bellows 34 to expand. At the same time, the diaphragm 24 is also displaced inward and eventually comes into close contact with the outer surface of the pack plate 7, stopping pressure transmission into the pressure receiving chamber in this state. Therefore, excessive pressure is not applied to the pressure sensor 12, and the pressure sensor 12 can be protected from destruction. The overload protection means 33 on the low pressure side operates in the same manner, so its explanation will be omitted. Further, the temperature characteristics of the pressure sensor 12 itself and the temperature characteristics of the pressure sensor 12 due to temperature changes of the cylindrical block 5, diaphragms 22, 24, sealed liquid, etc. are corrected by the resistor 38.

FIG. 4 is a longitudinal cross-sectional view of a pressure transmitter showing an embodiment in which the present invention is applied to a pressure transmitter. Items with the same reference numerals as in FIG. . In the pressure transmitter, the pressure chamber 9a and the pressure guide port 8 on the low pressure side, into which process pressure was introduced in the case of a differential pressure transmitter, are opened to atmospheric pressure. Since overload does not occur when atmospheric pressure is used, there is no need to provide a low-pressure side overload protection means indicated by reference numeral 33 in FIG. 1 and a bypass to provide this means. Other functions are the same as the differential pressure transmitter. Furthermore, if vacuum pressure is used instead of atmospheric pressure, the feed pressure transmitter functions similarly to the transmitters described above.

In each of the above embodiments, an example was shown in which the pressure sensor 12 and the seal terminal 16 were connected via the relay board 14. good. Moreover, the material of the sensor holder 13 does not need to be glass, and may be made of metal with a low coefficient of expansion. Further, in each of the above embodiments, the corrugated diaphragm 22,
Although an example using a diaphragm 24 has been shown, a flat diaphragm may also be used. Further, the number and arrangement of the seal terminals 16 are not limited to those in each of the embodiments described above, and can be changed in various ways.

〔Effect of the invention〕

As is clear from the above description, in the differential pressure/pressure transmitter according to the present invention, a pressure sensor is arranged to close one end of the center through hole of the cylindrical block inserted and fixed in the inner hole of the body. and the conductive member in the curved recess of the cylindrical block are connected with a seal terminal, and the pressure receiving diaphragms are respectively fixed to the back plates fixed to both end faces of the cylindrical block, and an overload protection means is installed in the through-hole bypass of the cylindrical block. By arranging the pressure sensor and the diaphragm close to each other, the passage for pressure transmission is not extremely short, and the volume inside the pressure receiving chamber is significantly reduced, making the entire instrument compact. In addition to being able to provide this product at a low cost (because it can be easily handled), the amount of sealed liquid is reduced, so the influence of expansion on the diaphragm is reduced, and pressure measurement errors due to temperature are reduced. Improves pressure measurement accuracy. Furthermore, since performance tests and inspections can be performed on the pressure receiving unit during assembly, and only those that pass can be assembled into the body, losses due to defective products during the manufacturing process can be significantly reduced. Furthermore, by providing a relatively deep recess in the cylindrical block and arranging a temperature correction resistor within this recess close to the pressure receiving chamber, there is not much of a difference between the measured temperature and the temperature inside the pressure receiving chamber. We can expect modern corrections.

[Brief explanation of drawings]

1 to 4 show an embodiment of the differential pressure/pressure oscillator according to the present invention, and FIG. 1 is a vertical sectional view of a differential pressure oscillator to which this is applied, and FIG. 2 is a sectional view taken along line AA in FIG. 1. , FIG. 3 is a BB sectional view of FIG. 2, and FIG. 4 is a longitudinal sectional view of a pressure transmitter to which the present invention is applied. 2・ψ・・Body, 2b−・・Body main body, 2c
...Inner hole, 5...Cylindrical block, 5a...
Recessed portion, 5b...through hole, 5c...e recessed portion, 6
, 7... Back plate, 9a. 11L@-...Pressure chamber, 12...Pressure sensor, 16
...-Seal terminal, 17...Life/hermetic seal, 21,23...Communication hole, 22,24...-Diaphragm, 26,27-Working/0 bellows hole, 32.33
...Overload protection device, 34°36 ・00. Bellows, 35.37... Spring, 38... Resistor. Patent applicant: Yamatake Honeywell Co., Ltd. Agent: Kazuko Yamakawa (and one other person)

Claims (2)

[Claims] (1) A cylindrical block that is inserted and fixed into the inner hole of the body and has a through hole in the center and a recess formed on the curved surface, and the through hole is closed in the recess formed on one end surface of this cylindrical block. When the pressure sensor is arranged as shown in FIG. A pair of back plates, one of which is fixed and has a communication hole between the recessed part and its outer surface, and the other has a communication hole between the through hole and its outer surface, and a peripheral edge part is airtightly fixed to each of these back plates. A pair of diaphragms arranged in a pressure introducing chamber, and an overload protection means arranged in a bus for the through hole formed in the cylindrical block and consisting of a bellows and a backup spring. Differential pressure/pressure transmitter. (2) A cylindrical block that is inserted and fixed into the inner hole of the body and has a through hole in the center and a recess formed on the circumference, and the through hole is closed in the recess formed on one end surface of this cylindrical block. a pressure sensor disposed to connect the pressure sensor to the conductive member in the recess, a seal terminal hermetically fixed through the cylindrical block so as to connect the pressure sensor and the conductive member in the recess, and a seal terminal hermetically fixed to both end surfaces of the cylindrical block, respectively. and a pair of back plates, one of which has a communication hole between the recessed part and its outer surface, and the other of which has a communication hole between the through hole and its outer surface, and a peripheral edge portion is hermetically fixed to each of these back plates. a pair of diaphragms disposed within the pressure introduction mechanism; an overload protection means disposed in a bypass for the through hole formed in the cylindrical block and consisting of a bellows and a backup spring; and a recess on the circumferential surface of the cylindrical block. 1. A differential pressure/pressure transmitter, comprising: a temperature correction resistor disposed within the seal terminal and connected to the seal terminal.