JPH04105030A - Differential pressure transmitter - Google Patents

Abstract

PURPOSE:To make zero point adjustment without provision of a three-way valve external to a differential pressure transmitter by providing a bypass, and furnishing a valve driving mechanism to control No.1-No.3 valve mechanisms, which opens and shuts each diaphragm side from the bypass. CONSTITUTION:When zero point adjustment is to be made, valve operating switches 41-43 and a zero point adjusting switch 44 are turned into the zero point adjust position, and in correspondence thereto current is fed to drive coils in a signal processing circuit 3, and valve mechanisms 8a, 8b are shut while another valve mechanism 12 is opened. Thereby the high pressure side and low pressure side upstream parts 9aa, 9ba of a U-form pressure medium passage 9 are closed while the high pressure side and low pressure side downstream parts 9ab, 9bb are put in communication through a bypass 11, which provides a uniform pressure in the parts 9ab, 9bb, and the same pressure is applied to both sides of a differential pressure sensing element 10. At this time, the sensing element 10 emits a differential pressure sensing signal when the differential pressure is zero, and this signal is passed to the signal processing circuit 3 via a signaling line 14, and thereby zero point adjustment is made. Thus zero point adjustment can be done without provision of any three-way valve mechanism external to a differential pressure transmitter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a differential pressure transmitter used in various plants and the like.

(Prior Art) As one of the differential pressure transmitters used in various plants, the one shown in FIG. 4 is conventionally known.

The differential pressure transmitter shown in this figure includes a block part 10 formed in a thick plate shape, and pressure receiving flange parts 102 provided on both sides of this block part 101, and connected to each pressure receiving flange part 102. Each process pipe 103a, 1
03b is detected and transmitted to the outside.

The block part 101 is a block body 1 formed in a thick plate shape.
05, a partition diaphragm 107 provided to cover each of the four parts 106 formed on both sides of the block body 105, and a pressure medium passage 108 formed in the block body 105 so as to communicate with each of the recesses 106.
A differential pressure detection element 109 provided approximately in the center of the block body 105 is inserted into a signal line hole 110 formed in the block body 105 so as to pass through the pressure medium passage 108 and the upper part of the block body 105. and said differential pressure detection element 1
a signal line 111 that guides the output of 09 to the outside, and a hermetic seal 112 that guides the signal line 111 to the outside while closing the signal line hole 110 of the block body 105;
A pressure medium 113 such as silicone oil or ethylene glycol is provided to fill the pressure medium passage 108 sealed by each partition diaphragm 107 and the signal line hole 110.

Further, each pressure receiving flange portion 102 includes a thick plate-shaped flange body 115 provided so as to cover each surface of the block body 105, and a peripheral groove 116 formed on the partition wall diaphragm 107 side of this flange body 115. (1)
The packing 117 to be inserted and each of these flange bodies 1
15 to both sides of the flange body 105.
It leads to the four parts 120 formed on the partition wall diaphragm side of the flange main body 115 through a passage hole 119 formed in the upper part of the flange body 115 .

Then, each process pipe 1 ('l 3a, 103b
If each partition diaphragm 1(]7 is distorted by the pressure from This detection result is output to the outside via the signal line 111.

In addition to such differential pressure transmitters, various structures are also known, but they are based on the same measurement principle.

(Problem to be Solved by the Invention) However, in such a differential pressure transmitter, slight permanent distortion occurs due to aging, excessive pressure, etc., and this may cause zero point drift.

Therefore, when installing such a differential pressure transmitter, a bypass pipe 1 is sometimes installed in each process pipe 103a, 103b in advance.
21, and each of these process piping 103
a, 103b and the stop valve 12 in the bypass pipe 121.
2a, 122b, and 122c are respectively attached to form the side of the three-way valve machine, and when adjusting the zero point, the stop valve 122C provided in the bypass pipe 121 is opened, and the stop valve provided in each process pipe 103a, 103b is opened. 1
22a and 122b are closed to make the pressure applied to the differential pressure detection element 109 the same, and after measuring the offset amount of the signal output from the differential pressure detection element 109, the stop valve 122C provided in the bypass pipe 121 is closed. is closed, and stop valves 122a and 122b provided in each process pipe 103a and 103b are opened to measure the differential pressure.

However, in this method, the zero point adjustment is performed by opening and closing the three-way valve mechanism, so if such a three-way valve mechanism cannot be provided due to process design constraints, the zero point adjustment is performed by opening and closing the three-way valve mechanism. There was a problem that adjustments could not be made.

In view of the above circumstances, it is an object of the present invention to provide a differential pressure transmitter that can perform zero point adjustment without providing a three-way valve mechanism outside the differential pressure transmitter.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, a differential pressure transmitter according to the present invention is provided at a position that interrupts a pressure medium passage formed in a block body so as to divide the pressure medium passage into two. a plate-shaped differential pressure detection element in which the pressure medium of each of the pressure medium passages is in contact with each side; a partition diaphragm that closes both ends of the pressure medium passage; and a bypass that bypasses both of the two divided pressure medium passages. a first valve mechanism for opening/blocking the bypass passage, and second and third valve mechanisms for opening/blocking each partition wall diaphragm side of the bypass passage of the pressure medium passage.
Opening of the valve mechanism and these first to third valve mechanisms/
It is characterized by comprising a valve drive unit that controls shutoff.

(Function) In the above configuration, the valve driving section controls the opening/closing of the first to third valve mechanisms to guide the pressure applied to each partition diaphragm to each surface of the differential pressure detection element. Pressure detection is performed, and zero point adjustment is performed by making the pressure applied to each surface of the differential pressure detection element the same.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of a differential pressure transmitter according to the present invention.

The differential pressure transmitter shown in this figure includes a block portion 1 formed in the shape of a thick plate, pressure receiving flange portions 2 provided on both sides of the block portion 1, and drive and control of the block portion 1 and the pressure receiving flange portions 2 provided on both sides of the block portion 1. Each process pipe 4a is equipped with a signal processing circuit 3 that performs signal processing, and is connected to each pressure receiving flange portion 2.

4b is detected and transmitted to the outside via the signal processing circuit 3. Further, when a zero point adjustment signal is supplied from the signal processing circuit 3, the block section 1 is driven to perform zero point adjustment.

The block part] is a block body 5 formed in a thick plate shape, and a partition diaphragm 7 provided to cover each of the four parts 6 formed on both sides of the block body 5, and each of the four parts 6 communicate with each other. As shown in FIG. a valve mechanism 88 provided at the low-pressure side upstream section 9ba of the U-shaped pressure medium passage 9; 1, and a valve mechanism 12 provided in the center of the bypass passage]1.

Furthermore, the block portion] is the U-shaped pressure medium passage 9.
The output of the differential pressure detection element 10 is passed through each signal line hole 13 formed in the block body 5 so as to pass through the block body 5 and the upper part of the block body 5.
and a signal line 14 that is inserted into each of the signal line holes 13 to connect the drive voltage of the signal processing circuit 3 to the valve mechanism 8a, 8b.
, 12, a hermetic seal 16 that guides each signal line 14, 15 to the outside while closing the signal line hole 13 of the block body 5, and the U sealed by each partition diaphragm 7. A pressure transmission medium 17 such as silicone oil or ethylene glycol is provided, which is filled in the shape of the pressure medium passage 9, the bypass path 11, and the signal line hole 13.

The valve mechanisms 88.8b are each U as shown in FIG.
A valve 19 accommodated in a chamber 18 formed in a high pressure side upstream section 9aa and a low pressure side upstream section 91)a of the letter-shaped pressure medium passage 9, and a hole 2 provided in the chamber 18.
a drive shaft 2 which is slidably inserted into the hole 2 and supports the valve 19 so as to be slidable in the directions of arrows A and B;
The needle portion 19a formed in the valve 19 by urging the drive shaft 21 in the six directions of the arrows causes the high-pressure side upstream portion 9aa and the low-pressure side upstream portion 9ha of the U-shaped pressure medium passage 9 to be connected to each other. and a spring 22 for closing each.

Further, the valve mechanisms 8a and 8b are each buried around the hole 20, and when a driving voltage is supplied through the signal line 15, the driving shaft 21 is moved along the arrow B as shown in FIG. 2(b). direction to release the closure by the needle portion 19a of the valve 19 and open the high pressure side upstream portion 9aa and the high pressure side downstream portion 9ab of the U-shaped pressure medium passage 9, or the U-shaped pressure medium passage 9. Low pressure side upstream part 9ba and low pressure side downstream part 91
) b.

The valve mechanism 12 also includes a valve 33 housed in a chamber 32 formed in the center of the bypass passage 11, and a hole 3 provided in the chamber 32, as shown in FIG. 3(a).
a drive shaft 35 that is slidably inserted into the hole 3 and supports the valve 33 slidably in the directions of arrows A and B;
4, a spring 36 is housed in the hole 34 and urges the drive shaft 35 in the six directions of arrows to close the bypass passage 11 with the needle portion 33a formed in the valve 33; and the signal line is buried around the hole 34. When a drive voltage is supplied through the drive shaft 15, the drive shaft 35 is moved in the direction indicated by the arrow B as shown in FIG.
A drive coil 3 that opens the bypass path 11 by biasing it in the direction
7.

Further, each pressure receiving flange portion 2 has a thick plate-shaped flange body 26 provided so as to cover each surface of the block body 5.
The packing 2 is (1) inserted into the peripheral groove 27 formed on the partition wall diaphragm 7 side of the flange main body 26.
8, and a bolt/nut mechanism 29 that brings each of these flange bodies 26 into close contact with both sides of the block body 5, and the pressure of the process piping 4a, 41) is transferred to a passage hole formed in the upper part of the flange body 26. 30 to the four portions 31 formed on the partition wall diaphragm 7 side of the flange main body 26.

Further, the signal processing circuit 3 includes a national body 40 formed in a rectangular shape, three valve operation switches 41 to 43 provided on the front of this national body 40, and a zero point adjustment switch 44, and the signal line 14 is connected to the signal line 14. Generates a differential pressure detection signal based on the signal from the differential pressure detection element] 0 and transmits it to the outside via the 4-mAD02 wire transmission line 45, and also connects each valve operation switch 41 43 or the zero point adjustment switch 44 is operated and a zero point adjustment instruction is given manually, a driving voltage is generated to control the valve mechanisms 8a, 8b,
The voltage is supplied to the 12 drive coils 23 and 37 to close them, and the zero and ψ adjustment of the differential pressure detection element 10 is performed.

Next, the differential pressure detection operation and zero point ff1l adjustment operation of this embodiment will be sequentially explained.

First, in the differential pressure detection operation, each valve mechanism 8a.

The drive coil 23 of 8b is brought into a non-driven state, and the high-pressure side upstream portion 9aa and the low-pressure side upstream portion 9b of the U-shaped pressure medium passage 9
At the same time, the driving coil 37 of the valve mechanism 12 is brought into a non-driven state, and the path 11 is brought into a closed state.

In this state, the pressure Pa applied to the high pressure side is transmitted to the pressure transmission medium 17 via the partition diaphragm 7, and then the high pressure side upstream portion of the U-shaped pressure medium passage 9 filled with this pressure transmission medium 17 is It is transmitted to the high-pressure side downstream portion 9ab of the U-shaped pressure medium passage 9 via the valve mechanism 8a of 9aa, and is transmitted to one side of the differential pressure detection element]0.

On the other hand, the pressure pb applied to the low pressure side is
After being transmitted to the pressure transmission medium 17 via the pressure transmission medium 17, the pressure transmission medium 17 is transmitted to the low pressure side downstream portion 9bb via the valve mechanism 8b of the low pressure side upstream portion 9ba of the U-shaped pressure medium passage 9 filled with the pressure transmission medium 17. and is transmitted to the other side of the differential pressure detection element 10.

At this time, since the bypass passage 11 is closed by the valve mechanism 12, the low pressure side and the high pressure side of the U-shaped pressure medium passage 9 are separated.

Therefore, in this state, the differential pressure detection element 10 generates a differential pressure detection signal having a value corresponding to the pressure difference Pa5Pb applied to both sides of the element 10, and sends this signal to the signal processing circuit 3 via the signal line 14. and output it to the outside.

Also, during the zero point adjustment operation, each valve operation switch 41 to 4
3 and the zero point adjustment switch 44 are set to the zero point adjustment position,
Correspondingly, the signal processing circuit 3 energizes each of the drive coils 23 and 37 to close the valve mechanisms 8a and 8b and open the valve mechanism 12.

As a result, the high pressure side upstream portion 9aa and the low pressure side upstream portion ba of the U-shaped pressure medium passage 9 are closed, and
The high-pressure side downstream section 9ab and the low-pressure side downstream section 9bb are communicated via the bypass path 11, so that the pressures of the high-pressure side downstream section 9ab and the low-pressure side downstream section 9b are uniform, and the same pressure is applied to both sides of the differential pressure detection element 10. is added.

At this time, a differential pressure detection signal when the differential pressure is zero is output from the differential pressure detection element 10, and this is supplied to the signal processing circuit 3 via the signal line 14 to perform zero point adjustment.

As described above, in this embodiment, when adjusting the zero point, the valve mechanism 8a installed in the high pressure side upstream section 9aa and the valve mechanism 8b installed in the low pressure side upstream section 9ba are closed, and
Since the valve mechanism 12 provided in the bypass path 11 is opened to equalize the pressure applied to both sides of the differential pressure detection element 10, zero point adjustment can be performed without installing a three-way valve mechanism outside the differential pressure transmitter. It is possible to do this.

Furthermore, since the valve mechanism 12 is provided inside the block body 5, there is a risk of malfunction due to corrosion if the process piping 4a, 4b is clogged with foreign matter contained in the fluid, unlike when the valve mechanism is provided externally. can be completely eliminated.

Further, in the embodiments described above, a semiconductor pressure sensitive element may be used as the differential pressure detecting element 10, or a capacitance type differential pressure detecting element may be used.

In addition, in the embodiment described above, each process pipe 4a
, 4b, the pressure difference between the fluid and the atmosphere may be detected by opening the low pressure side to the atmosphere.

Moreover, in the above-mentioned embodiment,! - Tor type valve] 9
．． 33, or a valve having a similar function, such as an O-ring seal type valve, may be used.

Further, in the embodiment described above, each drive coil 23.
37 to drive the valve 19.3B, or the valves 1≦ and 33 may be driven by another drive mechanism, such as a drive mechanism using a piezoelectric element J', a heat-sensitive element, etc.

〔Effect of the invention〕

As explained above, according to the present invention, zero point adjustment can be performed without providing a three-way valve mechanism outside the single-difference transmitter.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the differential pressure transmitter according to the present invention, FIG. 2 is a detailed cross-sectional view of the valve mechanism shown in FIG. 1, and FIG.
The figure is a detailed sectional view of the valve mechanism shown in FIG. 1, and FIG. 4 is a sectional view showing an example of a conventionally known differential pressure transmitter. 1...Block part 3...Valve drive part (signal processing circuit) 2...Pressure receiving flange part 5...Block body 7...Bulkhead diaphragm 9...Pressure medium passage 10...Differential pressure detection Element] 1 Bypass path 8a・Second valve mechanism 8b...Third valve mechanism 12・First valve mechanism

Claims (1)

[Claims] (1) a plate-shaped differential pressure detection element that is provided at a position that blocks a pressure medium passage formed in the block main body so as to divide it into two, and the pressure medium of each of the divided pressure medium passages is in contact with each surface; A partition diaphragm that closes both ends of the pressure medium passage, a bypass passage that bypasses both of the two divided pressure medium passages, a first valve mechanism that opens and closes the bypass passage, and a first valve mechanism that opens and closes the bypass passage. It is characterized by comprising: second and third valve mechanisms for opening/blocking each partition wall diaphragm side from the bypass passage; and a valve drive section for controlling opening/blocking of the first valve mechanism or the third valve mechanism. Differential pressure transmitter.