JPS6311827A - Zero point corrector for differential manometer - Google Patents

Abstract

PURPOSE:To correct a zero point deviation without interrupting the output of a measured value to the subsequent stage, by providing a zero-point correction assigning means, a changeover valve and piping to make equal two section chambers in pressure or open to the atmosphere in response to each zero-point correction assignment. CONSTITUTION:A differential manometer 1 is connected to a static pressure detection tube 3 and a total pressure detection tube 5 through a changeover valve 6. Normally, with the changeover valve 6, the detection tube 3 is connected to a section chamber A1 of the differential manometer 1 through a port 7 while the detection tube 5 is connected to a section chamber A2 through a port 8. With such an arrangement, normally, a subtractor 11 corrects a raw differential pressure data generated from the differential manometer 1 by the memory contents of a memory 10 and outputs a zero-point-corrected differential pressure data DELTAp-p0. At the zero-point correction assigned detection, a zero-point-corrected differential pressure data DELTAp-p0 immediately before the zero-point correction assigned detection is memorized with memory 12 and the current zero-point-corrected differential pressure data is outputted continually to the subsequent stage from the memory 12 with the differential pressure of the differential manometer 1 switched over to zero to update the contents of memory 10 through the changeover valve 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a differential pressure gauge that measures a slight differential pressure near zero differential pressure.

2. Description of the Related Art The dynamic pressure of a fluid flowing through a conduit will be explained using an example in which a pitot tube is used to detect the dynamic pressure.

The differential pressure gauge 1 consists of a first...
The static pressure P1 of the flow path 4 detected by the static pressure detection tube 3 is supplied to the first compartment A of the second compartments A□ and A2, and the total pressure P1 is supplied to the second compartment A2. The total pressure P2 detected by the pressure detection tube 5 is supplied.

Since the total pressure P2 is composed of the dynamic pressure ΔP and the static pressure P, the membrane plate 2 is placed on the first compartment A8 side as follows: P2-P1=Δ
It is pushed and deformed by an amount corresponding to P.

The flow velocity V of the flow path A is v=K"...■ However, since K can be expressed as a constant, the deformation of the membrane plate 2 can be detected by a strain gauge, semiconductor gauge, etc. attached to this membrane plate 2. Then, by substituting this differential pressure detection signal value EP into the first equation, the flow velocity V
is required.

Problems to be Solved by the Invention In such conventional differential pressure gauges, the zero point shifts due to changes in the surrounding layers, deterioration, and aging. However, differential pressure gauges are used to measure flow rates during processes and as speedometers in moving vehicles, etc. 2. Continuous use is required, and it is currently impossible to correct the zero point while in use. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a zero point correction device for a differential pressure gauge that can correct zero point deviation during use without interrupting the output of measured values to subsequent stages.

Means for Solving the Problems The zero point correction device of the differential pressure gauge of the present invention has two parts separated by a membrane plate.
Each of the two compartments has a pressure connection port, and at the differential pressure a1 that detects the difference between the two pressures according to the amount of distortion of the membrane plate, the two compartments are A switching valve and piping are provided to make the chambers at the same pressure or open to the atmosphere, and when zero point correction is instructed, the memory contents are updated to the differential pressure detection signal value when the two compartments are at the same pressure or open to the atmosphere.
A memory is provided, and a correction means is provided for correcting the differential pressure detection signal during metering without zero point correction using the stored contents of the first memory, and each time an instruction for zero point correction is given, the immediately preceding output after the correction is provided. The present invention is characterized in that a second memory for storing signals is provided.

According to this configuration, 1. In the normal use state, the correction means corrects the differential pressure raw data generated from the differential pressure gauge with the stored contents of the first memory, outputs the zero point corrected differential pressure data, and detects the zero point correction instruction. Sometimes, even when the second memory stores the zero point corrected differential pressure data immediately before the detection of the zero point correction instruction and the switching valve switches the differential pressure of the differential pressure gauge to zero in order to update the contents of the first memory. Continuously, the latest zero point corrected differential pressure data is output from the second memory to the subsequent stage.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 4.

FIGS. 1 to 3 show an embodiment at the time of dynamic pressure detection.

In FIG. 1, a differential pressure gauge 1 is connected to a static pressure detection tube 3 and a total pressure detection tube 5 via a switching valve 6. In normal use, the switching valve 6 is in the first switching state shown in FIGS. 1 and 2, and the static pressure detection tube 3 is connected to the first compartment A1 of the differential pressure gauge 1 via the port 7. , total pressure detection tube 5 is connected to port 8
It is connected to the second compartment A2 of the differential pressure gauge 1 via. The port 9 of the switching valve 6, which is open to the atmosphere, is closed and does not communicate with anything. Here, the zero point correction value p is stored in the first memory lO in advance. is written, in this first switching state, the differential pressure raw data ΔP generated from the differential pressure gauge 1 is applied to the subtracted input of the subtracter 11 as a correction means and is stored in the first memory. The stored contents of 10 are subtracted and zero point corrected differential pressure data (ΔP-po) is output to the second memory 12.

In the second memo January 2, when the switching valve 6 is in the first switching state, its contents are repeatedly updated to the output value of the subtractor 11, and the output of the second memory 12 is The latest zero point corrected differential pressure data (ΔP p
o) has occurred.

In FIG. 1, 13 is a zero point correction indicator.

When it is detected that the operating environment or the temperature of the differential pressure gauge 1 has changed by more than a specified temperature, a zero point correction instruction signal 14 is output. This signal 14 is transmitted to the switching valve 6 and the first. Second memory 10.12
It acts as a zero point correction instruction.

In response to the signal 14, the first winding 15 of the switching valve 6 is energized, and the switch 16 resists the biasing force of the spring 21 to enter the second switching state shown in FIG. In the second switching state, the switching valve 6 sides of the static pressure detection tube 3 and total pressure detection tube 5 are closed by ports 17 and 18, and the first and second compartments A, , A□ of the differential pressure gauge 1 are closed. Each is connected to the atmosphere through ports 19 and 20 and has the same pressure. Upon receiving the signal 14, the second memory 12 immediately prohibits updating of the contents and maintains the value immediately before the switching valve 6 enters the second switching state.

The first memory IO receiving the signal 14 switches the switching valve 6 to the second memory IO.
is updated to the differential pressure raw data ΔP of the switching state.

In this way, the switching of the switching valve 6 from the first to the second switching state, p of the contents of the first memory 10. When the update from Pa' to Pa' is completed, the switching valve 6 returns to the first switching state, and the second memory 12 repeatedly updates the contents to store the latest zero point correction differential pressure data (ΔP po'). It will start outputting and return to normal usage.

With this configuration, the zero point correction value is updated every time the zero point correction indicator 13 is instructed, and even during this updating operation, the second memory 12 stores the latest zero point corrected differential pressure data (ΔP po). Since the output is continued to the subsequent stage, the process using this differential pressure gauge 1 can be operated continuously without stopping the control.

In the above embodiment, during zero point correction, the first and second compartments A, .
A is opened to the atmosphere, but this is the same even if both compartments A and A2 are connected to the same location other than the atmosphere.

FIG. 4 shows an embodiment when static pressure is detected. Components having the same functions as those in FIG. 1 are given the same reference numerals. In FIG. 4, the total pressure detection tube 5 is eliminated and the second compartment A2 of the differential gauge 1 is
The only major difference is that it is open to the atmosphere.

In each of the above embodiments, the zero point correction value is automatically updated when the temperature fluctuates by more than a specified temperature. A similar effect can be expected by repeating the operation or by configuring the device so that the operator can manually issue a zero point correction instruction at an appropriate time.

Effects of the Invention - As explained, the zero point correction device of the differential pressure gauge of the present invention has the following advantages:
A switching valve that makes both compartments of the differential pressure gauge the same pressure or opens them to the atmosphere each time zero point correction is instructed.

a first memory that updates stored contents to differential pressure raw data output from a differential pressure gauge each time zero point correction is instructed; and a correction means that sometimes corrects the differential pressure raw data with stored contents of the first memory. , and a second memory for storing the immediately preceding output signal value of the correction means each time zero point correction is instructed, so that the switching valve is switched every time zero point correction is instructed even during normal use. The zero point correction value in the first memory is updated to perform accurate zero point correction, and even during this update at the time of zero point correction, the most recent zero point corrected differential pressure held in the second memory is sent to the subsequent stage. Data can be sent continuously, and the process etc. using the differential pressure gauge can be operated continuously even while the zero point correction value is being updated.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views showing the switching state of the switching valve in FIG. 1 during normal use and during updating of the zero point correction value, and FIG. FIG. 5 is a block diagram of another embodiment of the conventional differential pressure gauge. 1... Differential pressure gauge, 2... Membrane plate, 3... Static pressure detection tube,
5...Total pressure detection tube, 6...Switching valve, 10...First
memory, 11... subtractor [correction means], 12...
Second memory agent Yoshihiro MorimotoFigure 2Figure 3

Claims (1)

[Claims] 1. A differential pressure gauge that has a pressure connection port in each of two compartments separated by a membrane plate and detects the difference between the two pressures according to the amount of strain in the membrane plate, has a zero point correction indicating means, and has a zero point correction indicating means. A switching valve and piping are installed to make the two compartments at the same pressure or open to the atmosphere each time a correction is instructed, and when a zero point correction is commanded, the memory contents are changed to the differential pressure when the two compartments are at the same pressure or open to the atmosphere. A first memory for updating the detected signal value is provided, and a correction means is provided for correcting the differential pressure detection signal during measurement without zero point correction using the stored contents of the first memory, and the A zero point correction device for a differential pressure gauge, which is provided with a second memory that stores the output signal immediately after the correction.