JPS62207924A - Differential pressure measuring instrument - Google Patents

Abstract

PURPOSE:To prevent a differential sensor from being broken down, by providing an excessive pressure preventing mechanism, in addition to an automatic zero adjusting mechanism. CONSTITUTION:In case an excessive pressure has been applied to a high pressure chamber H, signals are generated to a microprocessor (muP) from the first pressure sensor P1 and the second pressure sensor P2, and the muP decides that the excessive pressure has been applied, from a difference of the signals of these two pressure sensors, and generates a signal for closing the first control valve Vd and opening the second control valve Vo. As a result, the pressure of the high pressure chamber H is stopped by the first control valve Vd, pressure of a low pressure chamber J is applied to a high pressure side of a differential pressure sensor Pd, through the second control valve Vo, a pressure difference goes to zero and balanced, and the differential pressure sensor is not broken down. Also, even in case an excessive pressure is applied from the low pressure chamber J, the differential pressure sensor Pd is not broken down in the same way.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a differential pressure measuring device, and more particularly to a high-precision differential pressure measuring device with intelligent functions.

<Prior Art> Conventionally, force balance type and displacement balance type devices have been used as differential pressure measuring devices and have been widely put into practical use.

<Problems to be Solved by the Invention> However, the conventional differential pressure measuring device described above does not have a function to automatically check zero point fluctuations and span fluctuations, and when performing such checks, m-determined input is required. There is the inconvenience of having to remove the device from the device and use a special tool to ram it.

Another problem is that it requires a complicated overpressure prevention mechanism.

The first invention of the present application is equipped with an automatic zero adjustment mechanism.

The second invention is equipped with an overpressure prevention mechanism in addition to the 9 automatic @ adjustment mechanism.

[1] The third invention is provided with an overpressure prevention mechanism and an automatic span adjustment mechanism in addition to an automatic zero adjustment mechanism, and has the object of realizing a differential pressure measuring device having high accuracy and high reliability.

<Means for Solving the Problems> The structure of the first invention for solving the above problems is as follows: a high pressure chamber and a low pressure chamber formed by fixing the peripheral edges of a seal diaphragm to both sides of a main body; A first pressure guiding means connecting the high pressure chamber and the low pressure chamber, a differential pressure sensor +i and a first control valve provided in the middle of the pressure guiding means, and a high pressure side and a low pressure side of the differential pressure sensor. It is provided with a second pressure guiding means connecting the two sides, a second control valve provided in the middle of the second pressure guiding means, and a control means for the first valve and the second valve.

A second invention adds first and second pressure sensors for measuring the pressures of the high-pressure chamber and the low-pressure chamber to the above-mentioned structure, and includes control means for controlling the first and second control valves. can be.

A third aspect of the present invention is the configuration of the second aspect, including a third pressure guiding means connecting the high pressure side and the low pressure side of the differential pressure sensor.

A third control valve and a reference pressure generating means are added in the middle of the third pressure guiding means, and a third control valve and a reference pressure generating means are added to the third pressure guiding means. Second. 3rd fIIJ
It is equipped with a control means for fitting the IIl valve.

<Embodiment> FIG. 1 is a cross-sectional configuration diagram showing an embodiment according to the first to third inventions of the present application. In the figure, 1 is a main body provided with seal diaphragms 2, 2a on both sides. This main body 1
A high pressure chamber 1. is located between the seal diaphragm 2. Low pressure chambers J are formed, these chambers are connected to a first chamber passing through the body 1.
are connected by a pressure guiding means 3. A differential pressure sensor Pd is disposed in the main body in the middle of the first pressure guiding means 3, and a first
A control valve Vd is provided.

Reference numeral 4 denotes a second pressure guiding means connecting the low pressure chamber J and the high pressure side of the vehicle pressure sensor Pd.
One end of the pressure guiding means is connected, and the other end is connected to the high pressure side of the differential pressure sensor, and a second control valve Vo is provided in the middle of this second pressure guiding means. The above is the configuration of the sensor side of the first invention.

Pl is a first pressure sensor that measures the pressure in the high pressure chamber 1;
P2 is a second pressure sensor that measures the pressure in the low pressure chamber J, and the sensor side of the second invention is configured by adding these pressure gauges P+ and P2.

5 is a third pressure guiding means connecting the low pressure chamber J and the high pressure side of the differential pressure sensor, and in the middle of this third pressure guiding means there is a reference pressure generating means consisting of a bellows 7 (a diaphragm may be used) and a spring 8; This is the third control valve Vs, and these mechanisms are added to constitute the senna side of the third invention.

FIG. 2 is a conceptual diagram showing a control means of the differential pressure measuring device shown in FIG. 1. In the figure, 20 is, for example, a Micro Lob O processor (μP), which outputs P8. It is a control means that controls the opening and closing of the first to third control valves Vd, Vo, and Vs based on the output signal of P2, and 21 is an external device (Ilo) that sends and receives signals to μP. In the following, the control means necessary for the first to third inventions will be shown, but in the case of the first and second inventions, only the necessary control means are selected.

In Figures 1 and 2, when in measurement mode.

μP sends an open signal to the first control valve Vd to the second control valve Vo.
gives a close signal. As a result, the differential pressure sensor 4 Pd
The differential pressure signal applied at that point is transmitted to μP. When checking one point, close the Vd control valve, open the VO control valve, apply the pressure PL of the low pressure chamber J to the high pressure side and low pressure side of the differential pressure sensor Pd, balance at the same pressure, and check the zero point. (first invention).

Next, 9. For example, if excessive pressure is applied to the high pressure chamber H, the first
pressure sensor P1 and second pressure sensor P2 to μP
A signal is issued, and μP determines that excessive pressure has been applied from the difference between the signals of these two pressure sensors, and sends a signal to close the first control valve Vd and open the second control valve vO. emanate. As a result, the pressure in the high pressure chamber I' is reduced to
The pressure of the low pressure chamber J is applied to the high pressure side of the differential pressure sensor Pd via the second control valve VO, and the pressure difference becomes zero and is balanced, and the differential pressure sensor Pd is destroyed. Never.

Similarly, if excessive pressure is applied from the low pressure chamber J,
μP determines that excessive pressure has been applied from the difference between the signals of the two pressure sensors, and sends a signal to open the first control valve Vd and open the second control valve VO. As a result, the low pressure chamber J
The excessive pressure is inputted to the high pressure side of the differential pressure sensor Vd through the second control valve Vo, and the pressure difference is balanced so that no damage occurs (second invention).

When checking the span, the first control valve V d 33 and the second
The third control valve VO is closed and the third control valve VS is opened.

As a result, the pressure of the low pressure chamber J is on the low pressure side of the differential pressure sensor Vd, and the pressure that has passed through the reference pressure generator 6 is on the high pressure side (in this example, the pressure is higher than the pressure of the low pressure chamber!! Semi-pressure) (using a generator) is applied.

Therefore, a constant differential pressure is always applied to the differential pressure sensor Pd (third invention).

According to the above configuration, the first invention can check the zero point, the second invention can automatically prevent the differential pressure sensor from being destroyed due to excessive pressure in addition to checking the zero point, and the third invention can automatically prevent the differential pressure sensor from being destroyed due to excessive pressure. In addition to the second aspect of the invention, the present invention can perform span checks, and these checks can be performed without removing the device from the line. Further, these checks can be performed automatically by giving a predetermined program to μP and switching the control valve at regular intervals.

Moreover, it is also possible to perform it arbitrarily as needed.

In addition, 1. Second pressure sensor P I r P 2 +
and each control valve may be provided separately from the main body 1.
It may be integrated into itself. Also, 1l19]
The number of valves and the pressure guiding means (pipes) are not limited to the above embodiments, and various modifications are possible.

<Effects of the Invention> According to the present invention, as described above in detail along with the embodiments.

(1) Maintenance is easy because checks can be performed while the device is attached to the measurement line.

(2) Because the differential pressure sensor is not protected from excessive pressure by a nest such as a diaphragm, the sealing film is less deformed and stress is small. Furthermore, hysteresis due to excessive pressure does not occur.

(3) All errors such as temperature coefficients, pressure coefficients, attitude errors, and aging can be removed by automatic zero adjustment and automatic span adjustment functions, resulting in large rangeability, high precision,
It is possible to achieve high reliability.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of the construction of an embodiment of the differential pressure measuring device of the present invention, and Fig. 2 is a conceptual diagram showing the LIJ control means of the differential pressure measuring device shown in Fig. 1. be.

1... Main body, 2, 2a... Seal diaphragm, 3
... first pressure guiding means, 4... second pressure guiding means, 5.
...Third pressure guiding means, 6...Reference pressure generating means, Pd
... Differential pressure sensor jj, P, ... First pressure sensor +P
2...Second pressure sensor, Vd...First control valve,
VO...Second series control jT+Vs...Third control valve.

Claims (3)

[Claims] (1) A high pressure chamber and a low pressure chamber formed by fixing the periphery of a seal diaphragm to both sides of the main body, a first pressure guiding means connecting the high pressure chamber and the low pressure chamber, and a first pressure guiding means connecting the high pressure chamber and the low pressure chamber; A differential pressure sensor and a first control valve provided midway;
A second pressure guiding means connecting the high pressure side and the low pressure side of the differential pressure sensor, a second control valve provided in the middle of the second pressure guiding means, and the first and second control valves. A differential pressure measuring device characterized in that it includes a control means. (2) A high pressure chamber and a low pressure chamber formed by fixing the peripheral edge of a seal diaphragm to both sides of the main body, a first pressure guiding means connecting the high pressure chamber and the low pressure chamber, and a first pressure guiding means connecting the high pressure chamber and the low pressure chamber; A differential pressure sensor and a first control valve provided midway;
A second pressure guiding means connecting the high pressure side and the low pressure side of the differential pressure sensor, a second control valve provided in the middle of the second pressure guiding means, and a second pressure guiding means that measures the pressure in the high pressure chamber and the low pressure chamber. 1. A differential pressure measuring device comprising: first and second pressure sensors; and control means for controlling the first and second control valves. (3) A high pressure chamber and a low pressure chamber formed by fixing the periphery of a seal diaphragm to both sides of the main body, a first pressure guiding means connecting the high pressure chamber and the low pressure chamber, and a first pressure guiding means provided in the middle of the pressure guiding means. a differential pressure sensor and a first control valve, a second pressure guiding means connecting a high pressure side and a low pressure side of the differential pressure sensor, and a second control valve provided in the middle of the second pressure guiding means. and first and second pressure sensors that measure the pressures of the high pressure chamber and the low pressure chamber, a third pressure guiding means connecting the high pressure side and the low pressure side of the differential pressure sensor, and a third pressure guiding means of the third pressure guiding means. A third control valve and a reference pressure generating means are provided on the way, and the first
, a differential pressure measuring device comprising control means for controlling the second and third control valves.