CN102778332B - Micro differential pressure generating and calibrating device - Google Patents

Abstract

The invention discloses a micro differential pressure generating and calibrating device, which relates to the micro differential pressure sensor detection and calibration technology and comprises two micro differential pressure sources in the same structure, a pressure lead pipe, a standard differential pressure meter and a differential pressure sensor to be calibrated, wherein the two micro differential pressure sources are respectively connected onto two pressure conveying openings of the differential pressure sensor to be calibrated and the standard differential pressure meter through the pressure lead pipe, and each micro differential pressure source consists of a cylindrical main air cylinder, a pressure adjusting piston cylinder, a precise pressure adjusting lead screw piston, a fine-adjustment piston cylinder, a fine-adjustment lead screw piston and a check valve. A series of micro differential pressures can be generated through the manual adjustment of the two micro differential pressure sources, the measuring value of the standard differential pressure meter is used as the reference, the measuring value and the deviation value of the differential pressure sensor to be calibrated are recorded through a computer, and the calibration of the differential pressure sensor to be calibrated is realized. The two micro differential pressure sources in the same structure are adopted, the positive and negative differential pressure regulation is convenient, the influence caused by ambient atmosphere is isolated, and the stability and the precision of the manufactured pressure can be easily maintained. The invention provides a determining method of key parameters of the device disclosed by the invention.

Description

Micro-pressure-difference occurs and calibrating installation

Technical field

The present invention relates to detection and the calibration technique field of micro-pressure sensor, device can produce and examine and determine some handkerchiefs to the micro-pressure-difference within the scope of one kPa.The object of the invention is, for the current pressure reduction pitot meter of lighter-than-air flight device such as blimp, captive balloon that is day by day used widely and the demarcation of utricule differential pressure pickup and calibration, to provide a set of device easy to use, with low cost.But other field, every demarcation and calibration relating to the differential pressure pickup of range in above-mentioned pressure differential range, equally can apply apparatus of the present invention.

Background technology

Monitor at Regional Atmospheric Environment in recent years, prevent and reduce natural disasters, under the driving of high resolving power real time monitoring, the demand such as early warning and missile defence, anti-terrorism, area communication, be widely used with the lighter-than-air flight device that soft unmanned airship and captive balloon are representative.This type of aircraft has two features:

One, air speed are very low, are generally less than 20m/s, and corresponding dynamic pressure is between 0 ~ 250Pa, and the typical range of differential pressure pickup used is about 400Pa;

Two, profile is airbag structure, maintains profile by implementing holding pressure control to utricule.Utricule and ambient atmosphere pressure reduction generally maintain between 200Pa ~ 700Pa, and differential pressure pickup typical case range used is about 1000Pa.

Carry out accurate calibration to the differential pressure pickup of above-mentioned range, the minimal pressure difference in the pressure reduction source of calibrating installation generates precision and stability needs the magnitude reaching Pa.With 1 standard atmospheric pressure 101325Pa for reference, 1Pa be about 1 standard atmospheric pressure 100,000/.Pressure reduction source is reached and to be stabilized in this level very difficult, only external minority producer can provide this series products at present, and price is very expensive.

By the Ideal-Gas Equation, in theory, if make the volume change 100,000 of the sealing gas of 1 standard atmospheric pressure/, the micro-pressure-difference producing about 1Pa between itself and a standard pressure can be made.Difficult is the stability how keeping pressure reduction.To so small pressure reduction, switch gate, the personnel pressure reduction pulsation that the atmospheric disturbance that causes formed such as to walk about all is enough to be flooded.

The present invention is by following thinking structure low cost micro-pressure-difference calibrating installation:

One, design accurate air-capacitor compression set, can make the volume change of airtight air be accurate to 100,000/, thus possess the ability of below 1Pa micro-pressure-difference;

Two, when micro-pressure-difference generation and calibrating installation work, isolate with ambient atmosphere, thus isolated atm difference disturbance.So, only there is the pressure reduction drift caused by faint heat interchange between pressure reduction source and atmospheric environment.Because thermal equilibrium process is a gradual process, the time that pressure reduction source keeps stable is at least point kind of a magnitude.

Three, micro-pressure-difference occur and calibrating installation in differential pressure measurement value (comprising the measured value of standard differential manometer measured value and differential pressure pickup to be checked) carry out synchronous acquisition by computing machine.Response time due to differential pressure pickup general < 1s, much smaller than the time constant that pressure reduction source is stable.As long as synchronous acquisition, the calibrating of drift on differential pressure pickup in pressure reduction source does not affect.

The ingenious part of above-mentioned thinking, is the traditional view broken, and namely as calibrating installation, the pressure reduction that pressure reduction source produces just must remain stable for a long time.In fact, from the angle analysis of application, as long as the stable time constant in pressure reduction source is far longer than the time constant of differential pressure pickup.Can greatly reduce costs like this.

Summary of the invention

The object of the invention is open a kind of micro-pressure-difference to occur and calibrating installation, the pressure reduction pitot meter and the utricule differential pressure pickup that can be the lighter-than-air flight device such as blimp, captive balloon of current increasingly extensive use are demarcated and are calibrated, and this device is easy to use, with low cost.

For achieving the above object, technical solution of the present invention is:

A kind of micro-pressure-difference occurs and calibrating installation, and it comprises a micro-pressure-difference source, a cylinder, standard differential manometer U7, differential pressure pickup U8 to be examined and determine and pressure guiding pipe U9;

Standard differential manometer U7, differential pressure pickup U8 to be examined and determine are parallel with one another, and two ends interlink with micro-pressure-difference source, cylinder respectively through pressure guiding pipe U9;

Micro-pressure-difference source comprises cylindrical primary stainless steel cylinder U1A, relief piston cylinder U2A, precision lead screw relief piston U3A, fine setting piston cylinder U4A, fine setting leading screw piston U5A, stop valve U6A, wherein, relief piston cylinder U2A, fine setting piston cylinder U4A, master cylinder U1A are communicated with each other;

Cylinder U1B casing wall is provided with stop valve U6B;

Standard differential manometer U7, differential pressure pickup U8 to be examined and determine are electrically connected with computing machine respectively, and both-way communication;

Can produce and examine and determine a few handkerchief to the micro-pressure-difference within the scope of one kPa, for demarcation and the calibration of the differential pressure pickup of range in above-mentioned scope.

Described micro-pressure-difference occurs and calibrating installation, and stop valve U6A, U6B described in it are manual or solenoid valve; Precision lead screw relief piston U3A is manual adjustments, or drive link is connected with the lead screw shaft be connected on step motor shaft with the form of leading screw sleeve, is regulated by stepper motor.

A kind of micro-pressure-difference occurs and calibrating installation, and it comprises micro-pressure-difference source, standard differential manometer U7, the differential pressure pickup U8 to be examined and determine and pressure guiding pipe U9 of two same configuration;

Micro-pressure-difference source comprises cylindrical primary stainless steel cylinder U1, relief piston cylinder U2, precision lead screw relief piston U3, fine setting piston cylinder U4, and fine setting leading screw piston U5, stop valve U6, relief piston cylinder U2, fine setting piston cylinder U4, master cylinder U1 are communicated with each other;

Standard differential manometer U7, differential pressure pickup U8 to be examined and determine are parallel with one another, and two ends interlink with two micro-pressure-difference sources respectively through pressure guiding pipe U9; Standard differential manometer U7, differential pressure pickup U8 to be examined and determine are electrically connected with computing machine respectively, and both-way communication;

Can produce and examine and determine a few handkerchief to the micro-pressure-difference within the scope of one kPa, for demarcation and the calibration of the differential pressure pickup of range in above-mentioned scope.

Described micro-pressure-difference occurs and calibrating installation, adopts the micro-pressure-difference source of two same configuration described in it, and first positive and negative pressure regulates more convenient, and it two is the impacts having isolated ambient atmosphere disturbance, ensure that and makes pressure precision and degree of stability.

Described micro-pressure-difference occurs and calibrating installation, and standard differential manometer U7 described in it, be High-precision standard differential manometer calibrated in advance, measuring error < 1Pa, resolution reaches 0.1Pa, and range is not less than 1000Pa.

Described micro-pressure-difference occurs and calibrating installation, and its operating process is as follows:

A) open stop valve U6A, U6B, cylinder U1A, U1B are communicated with air, guarantee that the initial pressure of cylinder air equals ambient pressure;

B) position of adjustment precision leading screw piston U3A, U3B, the air in cylinder U1A, U1B is made to be subject to slight compression or expansion, point-device adjustment is carried out to the volume of air in cylinder U1A, U1B, thus produces accurate and stable pressure reduction in two connectivity ports of standard differential manometer U7, differential pressure pickup U8 to be examined and determine;

C) finely tune leading screw piston U5A, U5B and further fine tuning is carried out to generated micro-pressure-difference;

D) pressure reduction that produces of pressure reduction source simultaneously by standard differential manometer U7 and differential pressure pickup U8 to be examined and determine sensitivity, and carry out synchronous acquisition by computing machine;

E) with the measured value of standard differential manometer U7 for benchmark, manually or stepper motor automatically regulate pressure reduction source, produce a series of standard pressure reduction, respectively by the measured value of standard pressure reduction under computer recording with differential pressure pickup U8 to be examined and determine, calibrating and the calibration for the treatment of calibrating sensor can be realized.

Described micro-pressure-difference occurs and calibrating installation, and the design parameter in micro-pressure-difference source described in it, comprising: cylinder U1 internal diameter D, interior length L, the piston diameter d of relief piston cylinder U2, the stepping that leading screw piston rotation one is enclosed is apart from x and leading screw range l, wherein, the minimal pressure difference in pressure reduction source generates precision δ P _min, estimated by following formula:

$\mathrm{\&delta;}{P}_{\min }\&ap;\frac{1}{2}\&CenterDot;101325\&CenterDot;{\left(\frac{d}{D}\right)}^2\frac{x}{L}$

The estimation equation of the maximum differential pressure range delta P that single pressure reduction source produces is as follows:

$\mathrm{\&Delta;P}=\mathrm{\&delta;P}\&CenterDot;\frac{l}{x}=2\&CenterDot;\mathrm{\&delta;}{P}_{\min }\&CenterDot;\frac{l}{x}.$

Apparatus of the present invention adopt the micro-pressure-difference source of two same configuration, make positive and negative pressure easy to adjust, and have isolated the pressure reduction pulsation that ambient atmosphere disturbance causes, and ensure that and make pressure precision and degree of stability.

Apparatus of the present invention have the following advantages:

1, low-down pressure reduction can be generated, and can meticulous adjustment be carried out;

2, isolated the impact of ambient atmosphere disturbance, pressure reduction stability is high;

3, pressure reduction is easy to adjust, and can need to produce positive pressure differential or Negative Pressure Difference according to calibrating;

4, simple and reliable, be easy to processing realize, with low cost.

Accompanying drawing explanation

Fig. 1 is the structural representation of micro-pressure-difference of the present invention generation and calibrating installation;

Fig. 2 is that the micro-pressure-difference that simplifies of the present invention occurs and the structural representation of calibrating installation;

Fig. 3 is minute-pressure generation and the calibrating installation structural representation that the present invention adopts electrical control mechanism;

Fig. 4 is the key design parameter schematic diagram of minute-pressure generation of the present invention and calibrating installation;

Fig. 5 is that the micro-pressure-difference implemented according to Fig. 1 occurs and the three-dimensional appearance schematic diagram of calibrating installation.

Embodiment

Apparatus of the present invention can produce and examine and determine several handkerchiefs common in above-mentioned field to the micro-pressure-difference within the scope of hundreds of handkerchief.This device comprises: the micro-pressure-difference source of two same configuration, pressure guiding pipe, High-precision standard differential manometer and level pressure gap sensor to be checked.These two micro-pressure-difference sources, by pressure guiding pipe, are connected on two defeated pressure mouths of standard differential manometer and level pressure gap sensor to be checked.Standard pressure reduction counts high precision differential manometer calibrated in advance, and require measuring error < 1Pa, resolution reaches 0.1Pa, and range is not less than 1000Pa.

Micro-pressure-difference source is the core of whole device, and by cylindrical master cylinder, relief piston cylinder, accurate voltage regulating leading screw piston, fine setting piston cylinder, fine setting leading screw piston and stop valve are formed.Relief piston cylinder, maintenance connection between fine setting piston cylinder and master cylinder.The present invention gives the defining method of micro-pressure-difference source key parameter, utilize the formula provided in invention, the micro-pressure-difference source lower than 1Pa generative capacity can be designed.

By rotating precision lead screw, pressure regulation leading screw piston can carry out minute adjustment to the volume of the air in master cylinder, thus produces the very high micro-pressure-difference of resolving accuracy.Fine setting leading screw can carry out fine tuning to generated micro-pressure-difference further.Stop valve is used for cylinder is communicated with air, makes the initial pressure of cylinder interior gas equal ambient pressure.

With the measured value of standard differential manometer for benchmark, manually regulate two pressure reduction sources can produce a series of standard pressure reduction, respectively by the measured value of standard pressure reduction under computer recording and level pressure gap sensor to be checked, calibrating and the calibration for the treatment of calibrating sensor can be realized.

As shown in Figure 1, micro-pressure-difference occurs and calibrating installation is made up of the micro-pressure-difference source of two same configuration, High-precision standard differential manometer U7, differential pressure pickup U8 to be examined and determine and pressure guiding pipe U9.Wherein, two micro-pressure-difference sources, by pressure guiding pipe U9, are connected on two defeated pressure mouths of standard differential manometer U7 and level pressure gap sensor U8 to be checked.Micro-pressure-difference source is the core of calibrating installation, and by cylindrical primary stainless steel cylinder U1, relief piston cylinder U2, precision lead screw relief piston U3, fine setting piston cylinder U4, fine setting leading screw piston U5, stop valve U6 are formed.Be communicated with between relief piston cylinder U2, fine setting piston cylinder U4 and master cylinder U1.

First calibrating installation is opened stop valve U6A, U6B, cylinder U1A, U1B is communicated with air, guarantee that the initial pressure of cylinder air equals ambient pressure before using.Close stop valve U6A, U6B afterwards.After this, when rotating the handle of precision lead screw piston U3A, U3B, the movement of leading screw piston U3A, U3B can make the air in cylinder U1A, U1B be subject to slight compression or expansion, thus produces micro-pressure-difference in two connectivity ports of standard differential manometer U7, differential pressure pickup U8 to be checked.

By the position of adjustment precision leading screw piston U3A, U3B, point-device adjustment can be carried out to the volume of the air in cylinder U1A, U1B, thus produce accurate and stable pressure reduction.Fine setting leading screw piston U5A, U5B can carry out fine tuning to generated micro-pressure-difference further.

Pressure reduction that pressure reduction source produces simultaneously by High-precision standard differential manometer U7 and differential pressure pickup U8 to be examined and determine sensitivity, and carry out synchronous acquisition by computing machine.Standard pressure reduction counts high precision differential manometer calibrated in advance, and require measuring error < 1Pa, resolution reaches 0.1Pa, and range is not less than 1000Pa.

With the measured value of standard differential manometer for benchmark, manually regulate two pressure reduction sources can produce a series of standard pressure reduction, respectively by the measured value of standard pressure reduction under computer recording and level pressure gap sensor to be checked, and under obtaining each standard pressure reduction point, the measured deviation value of differential pressure pickup U8, namely achieves the calibrating treating calibrating sensor.

The calibrating installation of Fig. 1, have employed the micro-pressure-difference source of two same configuration, the object done like this has two, and first positive and negative pressure regulates more convenient, and it two is the impacts having isolated ambient atmosphere disturbance, ensure that and makes pressure precision and degree of stability.As needs reduce costs, only can adopt a micro-pressure-difference source, calibrating installation is simplified to the structure of Fig. 2, be simplified to only surplus cylinder U1B and stop valve U6B by second pressure reduction source.It should be noted that, the object of reservation cylinder U1B and stop valve U6B is still the disturbance in order to isolation environment air.If eliminated, then micro-pressure-difference source is easy to receive the impact of ambient atmosphere disturbance (such as, switch gate, personnel such as to walk about at the pressure reduction pulsation that the atmospheric disturbance that causes is formed, and the pulsation of this pressure reduction is propagated with velocity of sound, and can at indoor roundtrip), by degree of stability enough for very difficult maintenance.When adopting a micro-pressure-difference source, pressure reduction formation range can reduce by half.

Micromatic setting (fine setting piston cylinder U4, fine setting leading screw piston U5) is non-essential, if the leading screw of regulator (piston cylinder U2, precision lead screw piston U3) is enough accurate, then micromatic setting can save.

If by Fig. 1 or Fig. 2, leading screw piston U3 changes driving stepper motor into by manual adjustments, and stop valve U6 also changes solenoid valve into by hand control valve, then micro-pressure-difference calibrating installation can be transformed into automatically controlled regulating device by manual regulating device.Fig. 3 gives the structural representation of automatically controlled micro-pressure-difference calibrating installation.

Fig. 4 gives the key design parameter in micro-pressure-difference source, comprising: cylinder U1 internal diameter D, interior length L, the piston diameter d of relief piston cylinder U2, and the stepping that leading screw piston rotation one is enclosed is apart from x, leading screw range l.The selection of above-mentioned parameter is the key of the height generation precision and stability realizing pressure reduction source.

The maximum volume of cylinder U1 can be obtained by L and D

$V=\frac{1}{4}\mathrm{\&pi;}{D}^{2}L---\left(1\right)$

By d and x, can determine when leading screw piston rotation one is enclosed, the volume change of the air in cylinder U1

$\frac{\mathrm{\&delta;V}}{V}=\frac{\frac{1}{4}\mathrm{\&pi;}{d}^{2}x}{\frac{1}{4}\mathrm{\&pi;}{D}^{2}L}={\left(\frac{d}{D}\right)}^2\frac{x}{L}---\left(2\right)$

The adjustment process of micro-pressure-difference, can be considered isothermal process, and according to the Ideal-Gas Equation, can derive, the pressure reduction caused when leading screw piston rotation one is enclosed is changed to

$\mathrm{\&delta;P}=P\&CenterDot;\frac{\mathrm{\&delta;V}}{V}\&ap;101325\&CenterDot;{\left(\frac{d}{D}\right)}^2\frac{x}{L}---\left(3\right)$

Wherein, P is the pressure in cylinder U1, is approximately equal to environmental stress, gets 1 standard atmospheric pressure during design.

Consider the factor of play that precision lead screw exists, regulation precision lead screw piston rotation 1/2 is enclosed, and the minimal pressure difference that the pressure reduction caused is changed to pressure reduction source generates precision, namely

$\mathrm{\&delta;}{P}_{\min }\&ap;\frac{1}{2}\&CenterDot;101325\&CenterDot;{\left(\frac{d}{D}\right)}^2\frac{x}{L}---\left(4\right)$

If expect, minimal pressure difference generative capacity is less than 1Pa, then by formula (4), design parameter need meet

${\left(\frac{d}{D}\right)}^2\frac{x}{L}<\frac{2}{101325}\&ap;2\&times;\&ap;{10}^{-5}---\left(5\right)$

By leading screw minimum step apart from x and leading screw range l, the producible maximum differential pressure scope in single pressure reduction source can be determined

$\mathrm{\&Delta;P}=\mathrm{\&delta;P}\&CenterDot;\frac{l}{x}=2\&CenterDot;\mathrm{\&delta;}{P}_{\min }\&CenterDot;\frac{l}{x}---\left(6\right)$

If micro-pressure-difference calibrating installation is pressed shown in Fig. 1, be equipped with two pressure reduction sources, then the maximum differential pressure scope of calibrating installation is 2 times of formula (6) estimation result.

A design example is provided below in conjunction with formula (1) ~ formula (6).Get the internal diameter D=10cm of cylinder U1, interior length L=30cm, the piston diameter d=1cm of precision lead screw piston U3, precision lead screw one encloses stepping apart from x=0.02cm, leading screw piston U3 effective travel l=20cm.Substitute into formula (4) can obtain, it is δ P that the minimal pressure difference in pressure reduction source generates precision _min=0.34Pa, can calculate single pressure reduction source maximum differential pressure scope by formula (6) is 675Pa.If calibrating installation adopts the structure of Fig. 1, then pressure reduction formation range is 1350Pa.Adopt Fig. 2 structure, then pressure reduction formation range is 675Pa.

Claims (4)

1. micro-pressure-difference occurs and a calibrating installation, it is characterized in that, comprises the micro-pressure-difference source of two same configuration, standard differential manometer U7, differential pressure pickup U8 to be examined and determine and pressure guiding pipe U9;

Micro-pressure-difference source comprises cylindrical primary stainless steel cylinder U1, relief piston cylinder U2, precision lead screw relief piston U3, fine setting piston cylinder U4, and fine setting leading screw piston U5, stop valve U6, relief piston cylinder U2, fine setting piston cylinder U4, master cylinder U1 are communicated with each other;

Standard differential manometer U7, differential pressure pickup U8 to be examined and determine are parallel with one another, and two ends interlink with two micro-pressure-difference sources respectively through pressure guiding pipe U9; Standard differential manometer U7, differential pressure pickup U8 to be examined and determine are electrically connected with computing machine respectively, and both-way communication;

Can produce and examine and determine a few handkerchief to the micro-pressure-difference within the scope of one kPa, for demarcation and the calibration of the differential pressure pickup of range in above-mentioned scope;

Wherein, the operating process of the generation of this micro-pressure-difference and calibrating installation is as follows:

A) open stop valve U6A, U6B, cylinder U1A, U1B are communicated with air, guarantee that the initial pressure of cylinder air equals ambient pressure;

B) position of adjustment precision leading screw piston U3A, U3B, the air in cylinder U1A, U1B is made to be subject to slight compression or expansion, point-device adjustment is carried out to the volume of air in cylinder U1A, U1B, thus produces accurate and stable pressure reduction in two connectivity ports of standard differential manometer U7, differential pressure pickup U8 to be examined and determine;

C) finely tune leading screw piston U5A, U5B and further fine tuning is carried out to generated micro-pressure-difference;

D) pressure reduction that produces of pressure reduction source simultaneously by standard differential manometer U7 and differential pressure pickup U8 to be examined and determine sensitivity, and carry out synchronous acquisition by computing machine;

E) with the measured value of standard differential manometer U7 for benchmark, manually or stepper motor automatically regulate pressure reduction source, produce a series of standard pressure reduction, respectively by the measured value of standard pressure reduction under computer recording with differential pressure pickup U8 to be examined and determine, machine computing as calculated, under obtaining each standard pressure reduction point, the measured deviation value of differential pressure pickup U8, namely achieves the calibrating treating calibrating sensor.

2. micro-pressure-difference as claimed in claim 1 occurs and calibrating installation, it is characterized in that, the micro-pressure-difference source of described two same configuration, first positive and negative pressure regulates more convenient, it two is the impacts having isolated ambient atmosphere disturbance, ensure that and makes pressure precision and degree of stability.

3. micro-pressure-difference as claimed in claim 1 occurs and calibrating installation, it is characterized in that, described standard differential manometer U7, for High-precision standard differential manometer calibrated in advance, measuring error < 1Pa, resolution reaches 0.1Pa, and range is not less than 1000Pa.

4. micro-pressure-difference as claimed in claim 1 occurs and calibrating installation, it is characterized in that, the design parameter in described micro-pressure-difference source, comprise: cylinder U1 internal diameter D, interior length L, the piston diameter d of relief piston cylinder U2, the stepping that leading screw piston rotation one is enclosed is apart from x and leading screw range l, wherein, the minimal pressure difference in pressure reduction source generates precision δ P _min, estimated by following formula:

$\mathrm{\&delta;}{P}_{\min }\&ap;\frac{1}{2}\&CenterDot;101325\&CenterDot;{\left(\frac{d}{D}\right)}^2\frac{x}{L}$

The estimation equation of the maximum differential pressure range delta P that single pressure reduction source produces is as follows:

$\mathrm{\&Delta;P}=\mathrm{\&delta;P}\&CenterDot;\frac{l}{x}=2\&CenterDot;\mathrm{\&delta;}{P}_{\min }\&CenterDot;\frac{l}{x}.$