CN100434875C - Ultrasonic flowmeter and its theory and technique - Google Patents

Abstract

The related ultrasonic flowmeter comprises: a sampling part, a computation part, and a keyboard display part, wherein sampling the oscillating number of oscillator 19 clockwise and counter-clockwise to obtain the sampling data N1' and N2'; and computing the flow velocity and flow rate by a SCM 24 based on principles and the 'extended transmission length technology'.

Description

A kind of ultrasonic flow meter is measured the method for fluid flow

Technical field

The present invention relates to a kind of can measuring channel in the ultrasonic flow meter of flow velocity, flow and ultrasound wave thereof velocity of propagation in its fluid of various fluids (potpourri of liquid, gas, mixtures of different liquids, gas with various) measure the method for fluid flow.Especially can significantly improve the measuring accuracy of ultrasonic flow meter, significantly enlarge measurement lower limit, significantly be fit to various calibers, and can record this fluid when static in current fluid, ultrasound wave is measured the method for fluid flow in the ultrasonic flow meter of velocity of propagation wherein.The invention still further relates to ultrasound wave heat meter and flowmeter standard scale.

Background technology

At present, the measuring principle of known ultrasonic flow meter has multiple different form, wherein mainly contains following two kinds, and the principle of their institute's foundations is as follows:

One, time difference method

According to Fig. 5:

The 1st, fluid downbeam ultrasonic emitting oscillator T ₁

The 2nd, fluid downbeam ultrasound wave pick-up dipole R ₁

The 3rd, fluid countercurrent current direction ultrasound wave pick-up dipole R ₂

The 4th, fluid countercurrent current direction ultrasonic emitting oscillator T ₂

L is T ₁And R ₁Between distance, also be T ₂With R ₂Between distance

C is the velocity of propagation of ultrasound wave in stationary fluid

U is a flow rate of fluid

" → u " represents the flow direction of fluid is the arrow direction

According to Fig. 5, when the ultrasonic propagation direction is consistent with fluid flow direction, i.e. fluid downbeam ultrasonic emitting oscillator T ₁Emission ultrasound wave, and fluid downbeam ultrasound wave pick-up dipole R ₁When receiving ultrasound wave, its velocity of propagation is c+u; And the ultrasonic propagation direction is when opposite with fluid flow direction, i.e. fluid countercurrent current direction ultrasonic emitting oscillator T ₂Emission ultrasound wave, and fluid countercurrent current direction ultrasound wave pick-up dipole R ₂When receiving ultrasound wave, its velocity of propagation is c-u.Hence one can see that, establishes t ₁Be ultrasound wave in fluid downbeam by T ₁Propagate into R ₁The used time:

Then

${\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=\frac{L}{c+u}---\left(1\right)$

If t ₂Be ultrasound wave in fluid countercurrent direction by T ₂Propagate into R ₂The used time then

${\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2=\frac{L}{c-u}---\left(2\right)$

Get by (1) formula and (2) formula

$2u=L(\frac{1}{t_1}-\frac{1}{t_2})---\left(3\right)$

Therefore, ultrasonic propagation time difference Δ t=t under the concurrent-countercurrent situation ₂-t ₁, then (3) formula can be expressed as:

$u=\frac{\mathrm{\&Delta;t}\&CenterDot;L}{2{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1\&CenterDot;(\mathrm{\&Delta;t}+t_1)}---\left(4\right)$

By (4) formula as can be known, rate of flow of fluid u with

Be directly proportional scale-up factor

Be constant, be not subjected to influence of temperature change, only need ultrasound wave following current travel-time t ₁And contrary, the following current of ultrasound wave is carried out computing and can be tried to achieve rate of flow of fluid u in L propagation mistiming Δ t substitution.

Above time difference method is write with reference to the 305th page, 310 pages, 311 pages of " flow measurement technology and instrument " books of China Machine Press's publication.This book is engraved into the printing of printing company limited by Beijing, the distribution of Xinhua Bookstore Beijing sale room, in June, the 2002 first published first impression.

Chief editor: beam state big Cai Wuchang

Coder: Zheng Jian Ying Cheng healthy and full of vigor peak

Two, sound round-robin method

Fig. 6 is the block scheme of an example of the ultrasonic flow meter of expression prior art.Ultrasonic flow meter shown in Figure 6 for example is disclosed in the non-patent document 1.As shown in Figure 6, ultrasonic oscillator 1 and 2 is configured to clamp the state of the stream 14 that flows through fluid. Ultrasonic oscillator 1 and 2 has played the function of transmitter and receptacle respectively.In other words, when ultrasonic oscillator 1 used as transmitter, ultrasonic oscillator 2 used as receiver; When ultrasonic oscillator 2 used as transmitter, ultrasonic oscillator 1 used as receiver.As shown in Figure 6, between the ultrasonic oscillator 1 and 2 flow direction of formed ultrasonic wave propagation path and fluid to be the θ angle lapping oblique.

When make ultrasound wave from ultrasonic oscillator 1 when ultrasonic oscillator 2 is propagated, because the relative fluid of ultrasound wave flows along advancing along direction, its speed just accelerates, on the contrary, when ultrasound wave from ultrasonic oscillator 2 when ultrasonic oscillator 1 is propagated, advance along contrary direction because the relative fluid of ultrasound wave flows, its speed is just slack-off.Therefore, poor by the ultrasonic propagation time of ultrasonic oscillator 1 to the ultrasonic propagation time of ultrasonic oscillator 2 and ultrasonic oscillator 2 to ultrasonic oscillator 1 can be obtained the speed of fluid.In addition, can also be by the sectional area of stream 14 and the long-pending flow of obtaining of flow velocity.

According to above-mentioned principle,, the measuring method by the sound round-robin method is described as the concrete grammar of asking fluid flow.

As shown in Figure 6, ultrasonic flow meter comprises sending part 3 and receiving portion 6, and ultrasonic oscillator 1 selectively is connected with a side in sending part 3 or the acceptance division 6 by switching part 10.At this moment, the sending part 3 that is not connected with ultrasonic oscillator 1 of ultrasonic oscillator 2 or the side in the acceptance division 6 connect.

When sending part 3 was connected with ultrasonic oscillator 1, sending part 3 drove ultrasonic oscillator 1, and the ultrasound wave of generation crosses mobile fluid and arrives ultrasonic oscillator 2.Ultrasound wave by ultrasonic oscillator 2 is received is converted into electric signal, and received signal is amplified by acceptance division 6.In zero cross detection portion 7, detect received signal and reach specified level first zero cross point afterwards, generate the zero cross detection signal.So-called zero cross point is meant, the amplitude of received signal from just to negative, or from negative to the point that is just changing.This zero cross point, arrive the moment of ultrasonic oscillator 2 as ultrasound wave.According to the zero cross detection signal, generate trigger pip in the moment of delay stipulated time, be input to sending part 3.Being called time delay from generation zero cross detection signal to the time that generates the trigger pip.

Sending part 3 drives ultrasonic oscillator 1 according to trigger pip, produces next ultrasound wave.The annular of this hyperacoustic transmission-reception-amplification, delay-transmission circulated repeatedly call sound circulation.Cycle index is called period.

In timing portion 9, the time that instrumentation stipulated number, repetitive cycling need, and the instrumentation result is sent to flow rate calculation portion 11.Then, switch switching part 10, ultrasonic oscillator 2 is used as transmitter, when ultrasonic oscillator 1 is used as receiver, carry out same measurement.

Deduct the value that delay time and sound period multiply each other from the time of measuring by said method, the value divided by gained after the sound period is ultrasonic propagation time again.If the travel-time t with ultrasonic oscillator 1 during as transmitter side ₁, the travel-time t when establishing ultrasonic oscillator 2 as transmitter side ₂

In addition, as shown in Figure 6, the distance of establishing between ultrasonic oscillator 1 and the ultrasonic oscillator 2 is L, and establishes flow rate of fluid and hyperacoustic velocity of sound is respectively u and c.

At this moment, t ₁And t ₂Formula below available is represented.

$\left.\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=\frac{L}{c+u\cos \mathrm{\&theta;}}\\ {\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2=\frac{L}{c-u\cos \mathrm{\&theta;}}\end{array}\right\}---\left(5\right)$

Can represent the following formula of flow velocity by following formula,

$u=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}(\frac{1}{t_1}-\frac{1}{t_2})---\left(6\right)$

If can obtain rate of flow of fluid u, just can be by the sectional area of stream 14 and the long-pending flow Q that obtains of flow velocity u.

(non-patent document)

NEC tester industry meeting specification, JEMI5032 " hyperacoustic hydrometry " NEC instrumentation industry meeting 1987.The sound round-robin method is taken passages in following " application for a patent for invention prospectus ".

[19] State Intellectual Property Office of the People's Republic of China

[12] application for a patent for invention prospectus

[21] application number 03123080.6

[51]INC CI ⁷

GOIF 1/66

[43] open day on November 12nd, 2003

[11] publication number CN1455230A

[22] April 30 2003 applying date

[21] application number 03123080.6

[71] applicant Panasonic Electric Equipment Industrial Co.,Ltd

Osaka, JAPAN mansion, address

[72] firm this refined man of virtue and ability of man of virtue and ability's bridge in the inventor China fir

[74] Zhongke Patent ﹠ Trademark Agency Co., Ltd of patent agency

Procurator Wang Huimin

Main two kinds of measuring principles of known ultrasonic flow meter in the above background technology: though time difference method harmony round-robin method has many superior parts, but these known ultrasonic flow meters are used for measuring little caliber rate of flow of fluid hour, because the precision of its flowmeter is subjected to instrument self to the time measurement error, the fluid caliber, the indeterminable constraint of rate of flow of fluid and physical quantity, promptly because the precision of flowmeter can not be higher than the precision of this flowmeter to time measurement, and caliber is more little, flow velocity is more little, the longshore current body is suitable respectively by caliber one side for ultrasound wave, it is more little that countercurrent direction propagates into mistiming of opposite side, little when this flowmeter self is unreachable to the time measurement precision when this mistiming, it is measured and just to have produced very big error, so that energy measurement not.

Summary of the invention

Be used to measure tubule footpath inner fluid speed hour in order to overcome known existing ultrasonic flow meter and principle thereof and technology, produce big error, the technical matters that its precision is greatly reduced the invention provides a kind of ultrasonic flow meter and principle thereof and technology.This ultrasonic flow meter and principle thereof and technology, can not only be applicable to the various occasions that present known ultrasonic flow meter is suitable for, and can significantly reduce tubule footpath inner fluid speed relative error hour, significantly improve the measuring accuracy of ultrasonic flow meter, significantly enlarge the measurement lower limit (can survey flow velocity littler in the little caliber) of ultrasonic flow meter, significantly be fit to the measurement of all size caliber inner fluid speed, flow.

The technical scheme that the present invention solves its technical matters is: the new principle that proposes a kind of ultrasonic flow meter measuring tube inner fluid speed, adopted a kind of new technology, having overcome known ultrasonic flow meter precision with this principle and technology retrained by fluid caliber and rate of flow of fluid, solved when rate of flow of fluid is very little, ultrasound wave respectively by caliber one side longshore current rate of flow of fluid along contrary direction propagate into mistiming of opposite side little to existing ultrasonic flow meter self to the time measurement precision when unreachable, to its immeasurablel problem.And with this principle and technological guidance and implemented the electronic circuit of ultrasonic flow meter.Discuss respectively from these three aspects below.

The new principle of ultrasonic flow meter measuring tube inner fluid speed:

Present principles is that 1. time difference methods in the background technology are furtherd investigate.Ultrasonic flow meter of the present invention and principle thereof and technology implementation example 1 block diagram:

If " → u " is the arrow direction for fluid flow direction, u is the mean flow rate of fluid on diameter D, c be ultrasound wave when this fluid is in static state in velocity of propagation wherein; The angle of its direction and rate of flow of fluid when θ propagates for the ultrasound wave following current, c ₁Be the velocity of propagation of ultrasound wave in fluid is flowed through pipe 35 media.

Ultrasound wave following current route of transmission and circuit working are promptly as follows along cyclic process:

Sending part 1 drive ultrasonic oscillator 28 emission ultrasound waves → through fluid flow through pipe 35 tube wall upside m points enter fluid flow through pipe 35 → along mo penetrate fluid flow through pipe 35 upside tube walls incide the o point → o point through refraction along oo ' penetrate fluid incide o ' point → o ' through refraction along o ' m ' penetrate fluid flow through manage 35 downside tube walls in m ' by ultrasonic oscillator 29 receptions → through the peak detector 3 of acceptance division 2 amplifications → just → or 7 → with a 11 → sending part 1, form ultrasound wave along circulation, establishing its ultrasound wave is f along cycle frequency _s., the cycle is T _S

The promptly contrary cyclic process of ultrasound wave adverse current route of transmission and circuit working is as follows:

Sending part 4 drive ultrasonic oscillators 30 emission ultrasound waves → through fluid flow through pipe 35 tube wall upside v points enter fluid flow through pipe 35 → along vu penetrate fluid flow through pipe 35 upside tube walls incide the u point → u point through refraction along uu ' penetrate fluid incide u ' point → u ' through refraction along u ' v ' penetrate fluid flow through manage 35 downside tube walls in v ' by ultrasonic oscillator 31 receptions → through the peak detector 6 of acceptance division 5 amplifications → just → or 9 → with a 12 → sending part 4, form the contrary circulation of ultrasound wave, establishing the contrary cycle frequency of its ultrasound wave is f _N., the cycle is T _N

If in the ultrasound wave following current route of transmission:

t ₁It is ultrasound wave required time of propagation distance oo ' in fluid;

Be that ultrasound wave is flowed through the pipe 35 tube wall upsides propagation mo used time of distance at fluid, flow through because of fluid and manage tube wall symmetry about in the of 35, so

Also be that ultrasound wave is flowed through the 35 used times of tube wall downside propagation distance o ' m ' of pipe at fluid.

To be ultrasound wave pick-up dipole 29 receive the circuit delay time that ultrasound wave is ordered through acceptance division 2, positive peak detector 3 or door 7, with door 11, sending part 1, ultrasonic emitting oscillator 28 to m at m ' to τ '.

t ₁' be ultrasound wave from m ' through τ ' institute through circuit, again through τ institute through approach and t ₁Through time of approach and.

If ultrasound wave following current route of transmission and adverse current route of transmission are to axle xx ' rotational symmetry.

If in the ultrasound wave adverse current route of transmission:

t ₂It is ultrasound wave required time of propagation distance uu ' (uu '=oo ') in fluid;

Being ultrasound wave flows through the 35 used times of tube wall upside propagation distance vu (vu=mo) of pipe at fluid, and also to be ultrasound wave certainly at fluid flow through manages the used time of 35 tube wall downside propagation distance u ' v ' (u ' v '=o ' m ').

" to be ultrasound wave pick-up dipole 31 receive the circuit delay time that ultrasound wave is ordered through acceptance division 5, positive peak detector 6 or door 9, with door 12, sending part 4, ultrasonic emitting oscillator 30 to v at v ' to τ.

t ₂' be ultrasound wave from v ' through τ " institute is through circuit, again through τ institute through approach and t ₂Through time of approach and.

According to above-mentioned set, should there be following formula to set up

$\left.\begin{array}{c}{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}={\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;}\\ {{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}={\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2+\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;}\end{array}\right\}---\left(7\right)$

(7) in the formula

$\left.\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=\frac{o{o}^{\&prime;}}{c+u\cos \mathrm{\&theta;}}\\ {\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2=\frac{u{u}^{\&prime;}}{c-u\cos \mathrm{\&theta;}}=\frac{o{o}^{\&prime;}}{c-u\cos \mathrm{\&theta;}}\end{array}\right\}---\left(8\right)$

By (8) formula

$c+u\cos \mathrm{\&theta;}=\frac{o{o}^{\&prime;}}{t_1}---\left(9\right)$

$c-u\cos \mathrm{\&theta;}=\frac{o{o}^{\&prime;}}{t_2}---\left(10\right)$

Because

c＝f·λ (11)

(11) in the formula:

F is the supersonic oscillations frequencies, and the oscillation frequency value that to establish this f value be exactly standard time-base generator 19.The ultrasound wave wavelength that λ is a ultrasound wave when above-mentioned f frequency, this frequency is far longer than f _s, f _N

We remove rate of flow of fluid u with λ more now,

$\frac{u}{\mathrm{\&lambda;}}=n---\left(12\right)$

(12) n is the multiple of u to λ in the formula.

The levoform of (11) formula and (12) formula substitution (9) formula and (10) formula is had

$c+u\cos \mathrm{\&theta;}=\mathrm{f\&lambda;}+\mathrm{n\&lambda;}\cos \mathrm{\&theta;}$

$=f(1+\frac{n\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}---\left(13\right)$

$c-u\cos \mathrm{\&theta;}=\mathrm{f\&lambda;}-\mathrm{n\&lambda;}\cos \mathrm{\&theta;}$

$=f(1-\frac{n\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}---\left(14\right)$

If (13) in the formula in the right formula

$f(1+\frac{n\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}=f{\mathrm{\&lambda;}}_1---\left(15\right)$

If (14) in the formula in the right formula

$f(1-\frac{n\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}=f{\mathrm{\&lambda;}}_2---\left(16\right)$

We define herein

Be the influence coefficient of rate of flow of fluid to the ultrasound wave wavelength

With (15) formula substitution (13) formula,

c+ucosθ＝fλ ₁ (17)

λ ₁Be the wavelength of ultrasound wave when oo ' direction is propagated

With (16) formula substitution (14) formula,

c-ucosθ＝fλ ₂ (18)

λ ₂Be the wavelength of ultrasound wave when uu ' direction is propagated

(17) formula subtracts (18) formula,

2ucosθ＝f(λ ₁-λ ₂) (19)

With (17) formula, (18) formula substitution (8) formula,

$\left.\begin{array}{c}{t}_{1}f=\frac{o{o}^{\&prime;}}{{\mathrm{\&lambda;}}_1}\\ t_{2}f=\frac{o{o}^{\&prime;}}{{\mathrm{\&lambda;}}_2}\end{array}\right\}---\left(20\right)$

Establish again

$\left.\begin{array}{c}{t}_{1}f=n_1\\ t_{2}f=n_2\end{array}\right\}---\left(21\right)$

n ₁Be ultrasound wave during along oo ' propagation, the ultrasound wave wave number on oo ' distance

n ₂Be ultrasound wave during along uu ' propagation, the ultrasound wave wave number on uu ' distance

With (21) formula substitution (20) formula,

${\mathrm{\&lambda;}}_1=\frac{o{o}^{\&prime;}}{n_1}---\left(22\right)$

${\mathrm{\&lambda;}}_2=\frac{o{o}^{\&prime;}}{n_2}---\left(23\right)$

With (22) formula and (23) formula substitution (19) formula,

$2u\cos \mathrm{\&theta;}=f(\frac{o{o}^{\&prime;}}{n_1}-\frac{o{o}^{\&prime;}}{n_2})$

Promptly

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{o{o}^{\&prime;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(24\right)$

(24) formula is the new principle of ultrasonic flow meter measuring tube inner fluid speed of the present invention.

The new technology that adopts:

New technology of the present invention is: when prolonging ultrasonic flow meter measurement rate of flow of fluid, the propagation distance of ultrasound wave in fluid is called for short " prolong and pass apart from technology " herein.

The following enforcement of this technology:

The molecule and the denominator of (24) formula equation the right formula be multiply by a positive integer N together,

Promptly

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{N}{N}\&CenterDot;\frac{o{o}^{\&prime;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(25\right)$

If

N ₂＝n ₂·N (26)

N ₂Be uu ' expansion N positive integer doubly after, ultrasound wave after enlarging apart from Nuu ' (Nuu '=Noo ') when propagating, the ultrasound wave wave number on distance Nuu '.

N ₁＝n ₁·N (27)

N ₁Be oo ' expansion N positive integer doubly after, ultrasound wave after enlarging apart from Noo ' propagation the time, the ultrasound wave wave number on distance Noo '.

With (26) formula and (27) formula substitution (25) formula,

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;{\mathrm{oo}}^{\&prime;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(28\right)$

Can find out N by (28) formula ₁, N ₂Be respectively oo ' and uu ', after promptly oo ' had enlarged N times, in the concurrent-countercurrent ultrasonic propagation required time, the number of oscillation of standard time-base generator 19 was because of oo ', uu ' all enlarge N doubly, so be called " prolong and pass apart from technology ".

(28) formula be the present invention after new technology is applied to new principle (24) formula, the new formula of the measurement that draws stream tube fluid flow velocity.In addition, new formula (28) formula of tube fluid flow velocity is flowed in the measurement that new principle (24) formula of ultrasonic flow meter measuring tube inner fluid speed of the present invention, new technology are applied to draw after new principle (24) formula, also can directly be released by this instructions (3) formula.

When (3) formula was applied to Fig. 1, the equation left side should be written as 2ucos θ, and (3) formula molecule, denominator get with multiply by f

$u=(\frac{1}{t_1}-\frac{1}{t_2})\&CenterDot;\frac{f}{f}\&CenterDot;\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}---\left(29\right)$

(29) in the formula, establish

t ₂f＝n ₂ (30)

t ₁f＝n ₁ (31)

(30) formula and (31) formula are actual is exactly (21) formula, with (30) formula and (31) formula substitution (29) formula, that is:

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(32\right)$

(32) formula is new principle (24) formula of ultrasonic flow meter measuring tube inner fluid speed of the present invention.

(32) formula equation the right molecule and denominator be multiply by positive integer N together, and with (26) formula and (27) formula substitution,

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{N}{N}\&CenterDot;\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(33\right)$

(33) formula is new formula (28) formula of the measurement stream tube fluid flow velocity that new technology of the present invention is applied to draw after new principle (24) formula.

Now, we use the new principle and the new technology of this ultrasonic flow again, try to achieve when detected fluid is in static state, and ultrasound wave is in velocity of propagation c wherein.

With (17) formula and the addition respectively of (18) formula both members

2c＝f(λ ₁+λ ₂) (34)

Get by (22) formula $n_{}$ ${}_1=\frac{o{o}^{\&prime;}}{{\mathrm{\&lambda;}}_1}$ (23) formula gets ${\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2=\frac{o{o}^{\&prime;}}{{\mathrm{\&lambda;}}_2}$ Substitution (34) Shi Kede

$2c=f(\frac{o{o}^{\&prime;}}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{o{o}^{\&prime;}}{n_2})---\left(35\right)$

Get by (35) formula

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{1}{n_2})\&CenterDot;\frac{o{o}^{\&prime;}}{2}\&CenterDot;f---\left(36\right)$

Be called for short " prolong and pass " with the present invention again, (36) formula the right formula molecule denominator be multiply by positive integer N together apart from technology,

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{1}{n_2})\&CenterDot;\frac{N}{N}\&CenterDot;\frac{o{o}^{\&prime;}}{2}\&CenterDot;f$

$=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;o{o}^{\&prime;}}{2}\&CenterDot;f---\left(37\right)$

Because among Fig. 1

$o{o}^{\&prime;}=\frac{D}{\sin \mathrm{\&theta;}}---\left(38\right)$

With (38) formula difference substitution (24) formula, (28) formula, (36) formula and (37) formula, draw following various respectively

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(39\right)$

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(40\right)$

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(41\right)$

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(42\right)$

In (39) formula and (41) formula, by (8) formula and (21) formula as can be known, n ₁Be that the ultrasound wave following current is propagated oo ' apart from required time t ₁The number of oscillation of interior standard time-base generator 19; n ₂Be that the ultrasound wave adverse current is propagated uu ' (uu '=oo ') apart from required time t ₂The number of oscillation of interior standard time-base generator 19.

And in (40) formula and (42) formula, by (25) formula, (26) formula and (27) formula as can be known, N ₁Be that doubly back required time t of oo ' distance expansion N is propagated in the ultrasound wave following current ₁The number of oscillation of the standard time-base generator 19 in the N; N ₂Be that the ultrasound wave adverse current is propagated uu ' (uu '=oo ') distance and enlarged doubly back required time t of N ₂The number of oscillation of the standard time-base generator 19 in the N.

D, f and θ are known numbers in (39) formula and (41) formula, so as long as energy measurement goes out n ₁And n ₂With regard to available (39) formula and (41) formula calculate respectively fluid flow through rate of flow of fluid u in the pipe 35 when being in static state with this fluid ultrasound wave and be under the different temperatures at fluid and all can measure in velocity of propagation c (c is measured in measurement during hydrodynamic) wherein.

But with (39) formula fluid measured flow velocity u, usefulness (41) formula survey ultrasound wave when fluid is static when wherein the velocity of propagation c, when having only f frequency in (39) formula and (41) formula more and more higher, could more and more reduce the measuring error of u and c, (39) formula and (41) formula be not owing to use new technology of the present invention, promptly be called for short " prolong and pass ", so it surveys result and " time difference method 1 " in the background technology and " sound round-robin method 2 " (n of u and c apart from technology ₂And n ₁Round-robin method equally after N time capable of circulation, is obtained its arithmetic mean in unison) be in same level, we are with (39) formula

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

Be called " new principle of ultrasonic measurement tube fluid flow velocity ".

And with (41) formula

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f$

Be called " ultrasound wave when tube fluid is dynamic, measure this fluid when static ultrasound wave in the new principle of velocity of propagation c wherein ".

For reach mention in this instructions " affiliated technical field " content " the present invention relates to a kind of can measuring channel in the flow velocity of various fluids (liquid; gas; mixtures of different liquids; the potpourri of gas with various); flow; and the ultrasonic flow meter of ultrasound wave velocity of propagation in its fluid and principle and technology, especially can significantly improve the measuring accuracy of ultrasonic flow meter, significantly enlarge measurement lower limit, significantly be fit to various calibers, and in the time of recording this fluid in current fluid and be in static state, ultrasound wave is in wherein ultrasonic flow meter and the principle and the technology of velocity of propagation " purpose.The present invention will " prolong pass apart from technology " be applied to (39) formula promptly " new principle of ultrasonic measurement tube fluid flow velocity " [hereinafter to be referred as " new principle (39) formula "] and (41) formula promptly " ultrasound wave when tube fluid is dynamic, measure this fluid when static ultrasound wave in the new principle of velocity of propagation c wherein " (hereinafter to be referred as " survey c new principle (41) formula "), get (40) formula and (42) formula respectively, promptly

$u=\frac{N_2-N_1}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$c=\frac{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2+N_1}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}{2\sin \mathrm{\&theta;}}\&CenterDot;f$

When using velocity of propagation c in this fluid of (40) formula and (42) formula fluid measured flow velocity u and ultrasound wave, can realize purpose of the present invention.(40) formula has contained the present invention's " new principle (39) formula " and new technology of the present invention " prolongation passes apart from technology ".

(42) formula has contained the present invention's " survey c new principle (41) formula " and new technology of the present invention " prolongation passes apart from technology ".

Should particularly point out: new technology of the present invention " prolongs and passes apart from technology " (6) formula that also can be used in the background technology " sound round-robin method 2 ", is about to (6) formula

$u=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}(\frac{1}{t_1}-\frac{1}{t_2})$

Equation the right molecule, denominator get with multiply by positive integer N

$u=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{N}{N}\&CenterDot;(\frac{1}{t_1}-\frac{1}{t_2})$

$=\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}\&CenterDot;(\frac{1}{N\&CenterDot;t_1}-\frac{1}{N\&CenterDot;t_2})---\left(43\right)$

If (43) in the formula

$\left.\begin{array}{c}N\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2=T_2\\ N\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=T_1\end{array}\right\}---\left(44\right)$

(44) in the formula, T ₂Be in " sound round-robin method 2 " electronic circuit block diagram 6, with ultrasonic oscillator 2 during as emitting side the emission ultrasound wave to ultrasonic oscillator 1 required time t ₂N doubly, T ₁Be with ultrasonic oscillator 1 as emitting side time emission ultrasound wave to ultrasonic oscillator 2 required time t ₁N doubly.

With (44) formula substitution (43) formula,

$u=(\frac{1}{T_1}-\frac{1}{T_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}---\left(45\right)$

Can reach goal of the invention of the present invention with the rate of flow of fluid u in the stream 14 of the fluid in (45) formula survey sheet 6.

(45) formula only is another expression-form of (40) formula in fact.Because if establishing frequency in (40) formula and be its cycle of vibration of the f frequency of punctual base oscillator 19 (Fig. 1 get the bid) is T, with the molecule of (40) formula the right formula, denominator with multiply by period T, then

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{T}{T}\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$=(\frac{1}{T_1}-\frac{1}{T_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}$

This formula is exactly (45) formula.So (45) formula also just becomes the content that the present invention is contained naturally.More than " prolong and pass " owing to adopted apart from technology, so its measuring error is far smaller than the error of known above-mentioned ultrasonic flow meter, make the precision of ultrasonic flow meter of the present invention be higher than the precision of known above-mentioned ultrasonic flow meter far away, thereby reached purpose of the present invention.

According to the above, the present invention has finished following four big contents from theory and technology, that is:

1. propose new principle of the present invention (39) formula, survey c new principle (41) formula.

2. new technology of the present invention is proposed---" prolong and pass ", i.e. (40) formula equation the right molecule apart from technology The distance that ultrasound wave is propagated in limited caliber D

Enlarge N doubly.Make the N in the formula of the right in (40) formula simultaneously ₂And N ₁Becoming ultrasound wave respectively propagates in contrary, following current

The number of oscillation apart from the standard time-base generator 19 in the required time; NL makes the distance L of ultrasonic propagation enlarge N doubly in the molecule of (45) formula equation the right, makes the T in the formula on the right in (45) formula simultaneously ₂, T ₁Become ultrasound wave respectively and broadcast the required time of NL distance in contrary, saequential transmission.

3. (40) formula, (42) formula are proposed promptly

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}{2\sin \mathrm{\&theta;}}\&CenterDot;f$

4. (45) formula is proposed promptly

$u=(\frac{1}{T_1}-\frac{1}{T_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}$

Now, come in the calculating chart 1 the fluid pipe 35 of flowing through, the fluid flow Q of elapsed time t _tIn actual measurement, fluid pipe 35 the flow velocity u that flows through is that t changes in time, and we will measure Q _tTime t be divided into a lot of junior unit Λ t _i, can be written as:

$t=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{\&Delta;}{t}_i,i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;,n---\left(46\right)$

Now establish fluid and flow through that pipe 35 xsect inner headed faces are long-pending to be S, then

$S=\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}---\left(47\right)$

If u _iBe at Λ t _iThe mean flow rate of the fluid in the time on the S area, then when (46) formula i value is big more, Λ t _iValue is just more little.As Λ t _iLittle to a certain degree the time, at Λ t _iFluid in time flows can regard steady flow as.Λ t like this _iMean flow rate u in time on the S area _iJust equal this steady flow flow rate of fluid, so can try to achieve Λ t _iIn time, the flow Q on the represented S area of (47) formula _i

$Q_i={\stackrel{\&OverBar;}{u}}_i\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}\&CenterDot;\mathrm{\&Delta;}{t}_i---\left(48\right)$

If Q _tBe by the flow in the t time on the represented S area of (47) formula, then in (46) formula t time

$Q_t=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Q}_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{u}}_i\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}\&CenterDot;\mathrm{\&Delta;}{t}_i(i=\mathrm{1,2,3},\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n)---\left(49\right)$

And (40) formula, (45) formula

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$u=(\frac{1}{T_1}-\frac{1}{T_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}$

The u that is obtained is actually the mean flow rate on (47) formula S disc diameter D.

By Reynolds number

$R_e=\frac{\mathrm{\&rho;}\&CenterDot;{\stackrel{\&OverBar;}{u}}_i\&CenterDot;D}{\mathrm{\&eta;}}---\left(50\right)$

(50) in the formula, R _eIt is the Reynolds number of detected fluid; ρ is the density of detected fluid; D is detected fluid pipe 35 the internal diameter of flowing through; η is the detected fluid kinetic viscosity or claims the coefficient of viscosity; u _iBe represented u in (48) formula _i:

When (50) formula

R _e≤2320 (51)

Detected fluid is a laminar condition.

When (50) formula

R _e＞2320 (52)

Detected fluid will begin to become turbulence state.

(40) formula and (45) formula are to be used for ultrasonic flow meter to measure the fluid that flows and had in the abundant developed pipe, the formula of the mean flow rate u on Fig. 1 fluid is flowed through pipe 35 diameter D.

When fluid is laminar condition

${\stackrel{\&OverBar;}{u}}_i=\frac{3}{4}u---\left(53\right)$

When fluid is turbulence state

${\stackrel{\&OverBar;}{u}}_i=\frac{2n}{2n+1}u---\left(54\right)$

(54) n in the formula is with the different positive numbers (n of non-12 formulas of n herein) that change of Reynolds number.(53) formula and (54) formula want to set up, must (40) formula and (45) formula meet " Shannon (shannon) sampling thheorem ": if the highest frequency of time dependent simulating signal [for Fig. 1, the u in (40) formula and (45) formula] exactly is f _c, as long as it is carried out enough samplings within a certain period of time, just can keep the character of this simulating signal, its condition is

$T<\frac{1}{2f_c}---\left(55\right)$

Wherein T is sampling period (the non-Fig. 1 of T gets the bid the concussion cycle of punctual base oscillator 19 herein), 2f _cBe minimum sample frequency.

T herein is at the Δ t of this calculating neutralization (46) formula _iFollowing relationship should be arranged, promptly

Δt _i≤T (56)

(55) formula, (56) formula are pointed out: the positive integer N in (40) formula and (45) formula can not unconfinedly increase.Because the increase of N must cause the growth of ultrasonic propagation distance, (40) formula, (45) formula N in (40) formula and (45) formula that samples respectively like this ₂, N ₁Period T also must prolong, the result is false (55) formula and (56) formula.

So (55) formula and (56) formula provide condition for the value of the positive integer N in (40) formula and (45) formula.When (55), when (56) formula is set up, get

$\left.\begin{array}{c}T<\frac{1}{2f_c}\\ \mathrm{\&Delta;}{t}_i\&le;T\end{array}\right\}---\left(57\right)$

By (8) formula:

${\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=\frac{o{o}^{\&prime;}}{c+u\cos \mathrm{\&theta;}}$

${\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2=\frac{o{o}^{\&prime;}}{c-u\cos \mathrm{\&theta;}}$

Know t ₂＞t ₁, with t ₂As the portion of time of sampling period T, the T of (57) formula is divided by the t of (8) formula ₂Promptly get " prolong pass apart from technology " promptly in (40) formula, (45) formula

N among the NL.

$N=\frac{T}{t_2}---\left(58\right)$

But (8) t of formula ₂Be to change with the u in (8) formula, when the variation range of u by u _MinChange to u _MaxThe time, its t ₂By t _2minChange to t _2max, the N of (58) formula will be by N at this moment _MaxChange to N _MinBecause in a single day the N in (40) formula and (45) formula gets fixed, will no longer change, at this moment, if get N _MaxAs the N in (40) formula and (45) formula, when rate of flow of fluid u is u _MaxThe time, the t that it is corresponding _2maxWith the value N of institute _MaxProduct the T of (58) formula will be increased, (55) formula is false; If get N _MinAs the N in (40) formula and (45) formula, when rate of flow of fluid u is u _MaxThe time, the t that it is corresponding _2maxWith the value N of institute _MinProduct (55) formula will also be set up.

From the above mentioned, should to get by u in (8) formula be u to the N in (40) formula and (45) formula _MaxThe time pairing t _2maxThe N that substitution (58) formula calculates _MinValue after rounding (do not round up, the numeral behind the radix point all takes down) is in (40) formula and (45) formula

N among the NL.In order to give calculating part single-chip microcomputer 24 with enough computing times, N can also suitably get little herein.

Through last argumentation, the N value of (40) formula and (45) formula can determine that (53) formula, (54) formula will be set up at this moment.With (40) formula, (45) formula respectively after substitution (53) formula and (54) formula, again with the u of (53) formula, (54) formula _iSubstitution (49) formula,

More than (39) formula, (40) formula, (41) formula, (42) formula, (45) formula, (59) formula, (60) formula, (61) formula, (62) formula, promptly

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f$

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f$

$c=(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f$

$u=(\frac{1}{T_1}-\frac{1}{T_2})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}$

All be τ, τ ' and the τ in (7) formula " push away under the situation about not considering, but actual using abovely when various, τ, τ ' and τ in (7) formula " must pay attention to.

Because (7) τ in the formula can basis

$\mathrm{\&tau;}=2\&times;\frac{1}{2}\mathrm{\&tau;}$

$=2\&times;\frac{\mathrm{om}}{c_1}$ (Fig. 1)

Accurately measure in advance; And τ ' and τ " also can before dispatching from the factory, accurately measure in advance by ultrasonic flow meter, so τ, τ ' and τ " all can regard known quantity as.

Now with the t in (7) formula ₁, t ₂(21) n of formula ₁, n ₂, the N of (27), (26) formula ₁, N ₂Respectively substitution is various about (39) formula, (40) formula, (41) formula, (42) formula, (45) formula, (59) formula, (60) formula, (61) formula and (62), can draw the formula of actual use.According to (7) formula, derive

$\left.\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1={{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;}\\ {\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2={{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;\&prime;}\end{array}\right\}---\left(63\right)$

With (63) formula substitution (21) formula

t ₁·f＝n ₁

t ₂·f＝n ₂

In,

$\left.\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1=t_{1}f=({{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;})f={{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}f-(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})\mathrm{<figure-callout\; id="2"\; label="f\; n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">f</figure-callout>}& \\ n_{}{}_2=t_{2}f=({{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;\&prime;})f={{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}f-(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})f\end{array}\right\}---\left(64\right)$

If (64) in the formula

$\left.\begin{array}{c}{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}f={{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}^{\&prime;}\\ {{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}f={{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;}\end{array}\right\}---\left(65\right)$

n ₁', n ₂' be respectively t in (7) formula ₁', t ₂The concussion number of times of the high frequency time-base generator 19 the in ' time

$\left.\begin{array}{c}(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})f={n_{\mathrm{\&tau;}}}^{\&prime;}\\ (\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})f={n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\end{array}\right\}---\left(66\right)$

n _τ', n _τ" be respectively (τ+τ ') in (7) formula, (τ+τ ") the concussion number of times of high frequency time-base generator 19 in the time

With (65) formula, (66) formula substitution (64) formula,

$\left.\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1={{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}\\ {\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2={{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\end{array}\right\}---\left(67\right)$

With (67) formula substitution (39) formula and (41) formula,

$u=(\frac{1}{{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(68\right)$

$c=(\frac{1}{{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}+\frac{1}{{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(69\right)$

(68) equation the right molecule, denominator get with multiply by positive integer N in the formula

$u=(\frac{1}{{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;}-{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;\&prime;}})\&CenterDot;\frac{N}{N}\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(70\right)$

(70) in the formula, establish

$\left.\begin{array}{c}{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^{\&prime;}N={{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}^{\&prime;}\\ {{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}^{\&prime;}N={{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}^{\&prime;}\\ {n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}N={N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\\ {n_{\mathrm{\&tau;}}}^{\&prime;}N={N_{\mathrm{\&tau;}}}^{\&prime;}\end{array}\right\}---\left(71\right)$

N ₂', N ₁', N _τ", N _τ' be respectively t in (7) formula ₂', t ₁', (τ+τ "), (τ+τ ') time enlarge the doubly concussion number of times of the high frequency time-base generator 19 of back in it of N

With (71) formula substitution (70) formula,

$u=(\frac{1}{{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{\mathrm{ND}/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(72\right)$

In like manner can get

$c=(\frac{1}{{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;}}+\frac{1}{{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{\mathrm{ND}/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(73\right)$

And according to (63) formula both members with after multiply by N,

$\left.\begin{array}{c}N\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2=({{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;\&prime;})N={{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}\&CenterDot;N-(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})N=T_2\\ N\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=({{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;})N={{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}\&CenterDot;N-(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})N=T_1\end{array}\right\}---\left(74\right)$

If (74) in the formula

$\left.\begin{array}{c}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}\&CenterDot;N={{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}^{\&prime;}\\ (\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})N={T_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\\ {{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}\&CenterDot;N={{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">T</figure-callout>}}_1}^{\&prime;}\\ (\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})N={T_{\mathrm{\&tau;}}}^{\&prime;}\end{array}\right\}---\left(75\right)$

After (75) formula substitution (74) formula, substitution again (45) formula gets

$u=(\frac{1}{{{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="C20051008869400351.png,C20051008869400371.png"\; state="\{\{state\}\}">T</figure-callout>}}_1}^{\&prime;}-{T_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}^{\&prime;}-{T_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{N\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\cos \mathrm{\&theta;}}---\left(76\right)$

After (72) formula substitution (53) formula, (54) formula, substitution again (49) formula; After (76) formula substitution (53) formula, (54) formula, substitution again (49) formula,

More than (72) formula, (73) formula, (76) formula, (77) formula, (78) formula, (79) formula and (80) formula, τ, τ ', the τ in considering (7) formula exactly " time formula that draws, these formulas can be used when actual condition.

The relevant theory of following basis is determined N, determines that N has two kinds of ways:

First experience is determined method: " in the TT﹠C system of computer industry production run, the sampling period is indicated by sampling thheorem usually and selects f _sCriterion, and determine T by actual experiment _sAccording to the accumulation of protracted experience, often table look-up and select T according to the empirical data shown in the table 10-1 _sFrom table 10-1 as seen, should get different sampling period T for different controlled variables _s".T has been arranged _s, determine N according to (58) formula again.

The empirical data table in table 10-1 sampling period

Controlled variable	Sampling period T s(second)	The preferential T that uses s(second)
			Flow	1-5	1-2

Below rule of thumb come to determine T _sTake passages in:

The 465th page of " national computer grade examination study course (three grades of A)---hardware technology and application " book, this book is published by the Electronic Industry Press, Chen Tienian, Sun Dewen chief editor, in June, 1997 first published, the first impression in June, 1997.

It two is to determine according to Shannon's sampling theorem, in this manual just can be according to (55) formula

$T<\frac{1}{2f_c}$

(56) formula

T≤Δt _i

And (58) formula

$N=\frac{\mathrm{<figure-callout\; id="2"\; label="T\; t"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">T</figure-callout>}}{t_{}}$

To t ₂Get t _2maxThe time, get N _MinBe (72), (73), (76), (77), (78), (79), (80) N in various.

Detected fluid for the flow velocity acute variation, should take into full account technical dynamic requirements, in this case, also available Shannon's sampling theorem is determined N, need according to the 37th page of " flow measurement technology and instrument " book, dynamic perfromance Fig. 2 of flow instrument-4, the family curve of 1 time domain representation in the flowmeter dynamic response characteristic curve, curve is replaced with a function v=v (t), and the maximal value of its v (t) is with the measurement upper limit v of general ultrasonic flow meter _MaxReplace, obtain 63v _MaxThe value of %, according to the quality time constant T (non-sampling period T of the present invention of T herein or ultrasound wave period T are the T of former book content meaning) of dynamic response time domain representation method dynamic response, T is that v (t) increases to 63v from 0 then _MaxThe used time of %, the more little dynamic response of T is good more, so according to the requirement of quality time constant T, can obtain concrete function v=v (t); Replenish the function variable field of definition again, make v=v (t) in (T ,+T) upward continuous, convergence; Exhibition is Fu Shi progression again, and consideration needs the overtone order of consideration according to Fu Shi progression, can obtain the 2f in (55) formula _c, also can calculate its maximum sampling period T certainly according to (55) formula, the N value of Que Dinging can make ultrasonic flow meter satisfy fluid dynamic properties like this, and its dynamic response is good.

More than " flow measurement technology and instrument " book, its this instructions of situation is mentioned, no longer repeats at this.

General typical ultrasonic flow meter is measured the rate of flow of fluid scope:

Detected fluid is a gas, measures caliber (mm) 200-400, and measurable flow speed scope is 2.5-25m/s; Detected fluid is water or other liquid, measures caliber 1-15m, and measurable flow speed scope is 0.3-20m/s, and measures caliber (mm) 100-200, and measurable flow speed scope is 0.5-20m/s.(this general typical ultrasonic flow meter is measured the rate of flow of fluid scope and is selected from " airborne sensor application manual " 469 page table 12-27 ultrasonic flow sensors.This book is that China Machine Press publishes, June nineteen ninety-five first published, in October, 1997 the third printing.The printing of Seiko printing house, Changping, Beijing, the distribution of Xinhua Bookstore Beijing sale room.)

τ ' during following formula is various, τ ", in the ultrasonic flow timing of actual shop drawings 1, because of the randomness of the selected circuit devcie delay performance of each ultrasonic flow meter, so " neither meeting is identical for the τ ' of each ultrasonic flow meter, τ.But when being fabricated to finished product owing to ultrasonic flow meter, every selected circuit devcie of ultrasonic flow meter just selects, so the τ ' in various, τ " are confirmable.

Because in (72) formula, (73) formula, (76) formula, (77) formula, (78) formula, (79) formula and (80) formula, because of prolonging N, D/sin θ and L doubly carry out continuously, so N _τ', N _τ", T _τ', T _τ" can doubly determine after the whole continuous coverage in back D/sin θ and L prolongation N, must be worth the back and use for programming.

By above we can also obtain conclusion: ultrasonic flow meter of the present invention and principle thereof and technology: 1. the frequency f of the standard time-base generator 19 among Fig. 1 is high more, and its measuring error is more little, and precision is high more.2. under the prerequisite that can satisfy Shannon's sampling theorem, the sampling period is long more, and the N that the present invention " prolongs and passes apart from technology " is big more, and its measuring error is more little, and for steady flow, its precision is also high more; Instability is flowed, because the prolongation in sampling period, its dynamic response quality descends, and measuring error will increase, the also corresponding reduction of precision, but still in the sampling thheorem restricted portion.In actual applications, should get the frequency f of suitable sampling period and standard time-base generator 19, make ultrasonic flow meter dynamic response quality of the present invention and cost, can satisfy actual needs again simultaneously so that grasp according to requirement of actual working condition.

During the useful effect of the present invention, overcome known existing ultrasonic flow meter and be used to measure tubule footpath inner fluid speed hour, produce big error, the problem that its precision is greatly reduced, significantly reduce tubule footpath inner fluid speed error hour, significantly enlarge the measurement lower limit of ultrasonic flow meter, significantly improved the degree of accuracy of ultrasonic flow meter, significantly be fit to the measurement of streaming flow in all size caliber.

Description of drawings

Fig. 1 is the theory diagram of the embodiment 1 of explanation ultrasonic flow meter of the present invention and principle and technology.

Fig. 2 is the theory diagram of the embodiment 2 of explanation ultrasonic flow meter of the present invention and principle and technology.

Fig. 3 is the theory diagram of the embodiment 3 of explanation ultrasonic flow meter of the present invention (calorimeter) and principle and technology.

Fig. 4 is the theory diagram of the embodiment 4 of explanation ultrasonic flow meter of the present invention (calorimeter) and principle and technology.

Among the figure:

1, sending part

2, acceptance division

3, positive peak detector

4, sending part

5, acceptance division

6, positive peak detector

7 or the door

8, monostable

9 or the door

10, monostable

11, with door

12, with door

13, single-chip microcomputer asynchronous counter (or asynchronous counter)

14, single-chip microcomputer asynchronous counter (or asynchronous counter)

15, with door

16, bistable

17, with door

18, bistable

19, standard time-base generator

20, count section

21, count section

22, I/O interface chip

23, I/O interface chip

24, single-chip microcomputer

25, keyboard, display interface chip

26, display part

27, keypad portion

28, ultrasonic emitting oscillator

29, ultrasound wave pick-up dipole

30, ultrasonic emitting oscillator

31, ultrasound wave pick-up dipole

32, temperature-sensing element (device)

33, temperature-sensing element (device)

34, amplifier

35, the fluid pipe of flowing through

36, amplifier

37, A/D interface chip

38, ultrasonic emitting, pick-up dipole

39, ultrasonic emitting, pick-up dipole

40, electronic analog swtich

41, electronic analog swtich

Embodiment

Preferred embodiment with regard to ultrasonic flow meter of the present invention (calorimeter) and principle and technology describes below.

For the convenience of problem, establish at this:

The ultrasonic flow meter sampling period is T _c

Ultrasonic flow meter is T along the circulating sampling cycle _Sc, frequency is f _Sc

The contrary circulating sampling cycle of ultrasonic flow meter is T _Nc, frequency is f _Nc

Ultrasound wave is T along cycle period _s, frequency is f _s

The contrary cycle period of ultrasound wave is T _N, frequency is f _N

T _cBe the Δ t in (59), (60), (61), (62), (77), (78), (79), (80) formula _i

T _ScWhen not considering τ, τ ', τ " time, be in (40), (42), (59), (60) formula ultrasonic flow meter along circulating sampling N ₁The value required time is the T in (45), (61), (62) formula ₁, i.e. T _Sc=T ₁When considering τ, τ ', τ " time, be the suitable circulating sampling N of ultrasonic flow meter in (72), (73), (77), (78) formula ₁' value required time is the T in (76), (79), (80) formula ₁', i.e. T _Sc=T ₁'.Essence is to finish N ultrasound wave along the used time of circulation.

T _NcWhen not considering τ, τ ', τ " time, be the contrary circulating sampling N of ultrasonic flow meter in (40), (42), (59), (60) formula ₂The value required time is the T in (45), (61), (62) formula ₂, i.e. T _Nc=T ₂When considering τ, τ ', τ " time, be the contrary circulating sampling N of ultrasonic flow meter in (72), (73), (77), (78) formula ₂' value required time is the T in (76), (79), (80) formula ₂', i.e. T _Nc=T ₂'.Essence is to finish the contrary used time of circulation of ultrasound wave N time.

What be worth proposition is that above-mentioned each amount all is functions of the fluid measured flow velocity u of institute.

Preferred embodiment with regard to ultrasonic flow meter of the present invention (calorimeter) and principle and technology describes below

(embodiment 1)

Fig. 1 is the theory diagram of ultrasonic flow meter of the present invention and principle and technology implementation example 1.

Embodiment 1 ultrasonic flow meter comprises: sending part 1, acceptance division 2, positive peak detector 3, sending part 4, acceptance division 5, positive peak detector 6, or door 7, monostable 8, or door 9, monostable 10, with door 11, with door 12, single-chip microcomputer asynchronous counter 13, single-chip microcomputer asynchronous counter 14, with door 15, bistable 16, with door 17, bistable 18, standard time-base generator 19, count section 20, count section 21, I/O interface chip 22, I/O interface chip 23, single-chip microcomputer 24, keyboard and display interface chip 25, display part 26, keypad portion 27, ultrasonic emitting oscillator 28, ultrasound wave pick-up dipole 29, ultrasonic emitting oscillator 30, ultrasound wave pick-up dipole 31, fluid is flowed through and is managed 35.

Ultrasonic flow meter shown in Figure 1 is broadly divided into three parts, sampling section, calculating section and keyboard display part.

Sampling section is made of jointly count section among Fig. 1 20,21 two count section of count section (be all asynchronous counter, its figure place should satisfy sample requirement and surpass demand) and each circuit block of the left side thereof.

Calculating section is made up of single-chip microcomputer 24.

Sampling section is connected by I/O interface chip 22, I/O interface chip 23 with calculating section.

In sampling section, standard time-base generator 19 is not controlled by remaining part and rate of flow of fluid in Fig. 1 circuit, as long as connect

Energize just ceaselessly vibrates, and output is higher than the high frequency square wave spike train of ultrasound wave along circulation and the contrary cycle frequency of ultrasound wave far away.

Sampling section is sampled or is not sampled, by the control assembly bistable 16 in the sampling section, bistable 18, monostable 8, monostable 10, with door 11, with door 12, with door 15, control (all with door or door all band application schmitt trigger) with door 17 or door 7 or door 9, and these control assemblies directly or indirectly are subjected to the control of the single-chip microcomputer 24 of single-chip microcomputer asynchronous counter 13 (or asynchronous counter), single-chip microcomputer asynchronous counter 14 (or asynchronous counter) and calculating section in the sampling section selectively.

The beginning in each sampling period must be caused by the I/O mouth B end output one high level square-wave signal of calculating section single-chip microcomputer 24, controls control assembly bistable 16, bistable 18 set in the sampling section simultaneously, even its Q end is all high level.The Q of bistable 18 end high level open with door 17 and with door 12, with door 17 the high-frequency impulse series of standard time-base generator 19 is counted by entering count section 21 with door 17; Make with door 12: the high level signal of the I/O mouth B of single-chip microcomputer 24 end monostable 10 produce an output positive pulse signal by or door 9 allowed by being input to and activating sending part 4 with door 12; And the Q of bistable 16 end high level open with door 15 and with door 11, with door 15 the high level pulse series of standard time-base generator 19 is counted by entering count section 20 with door 15, is made with door 11: the high level signal of the I/O mouth B of single-chip microcomputer 24 end monostable 8 produce an output positive pulse signal by or door 7 allowed by being input to and activating sending part 1 with door 11.

Sending part 4 drives countercurrent direction ultrasonic emitting oscillator 30 emission ultrasound waves and passes vu-uu '-u ' v ' path, received by adverse current ultrasound wave pick-up dipole 31, again after acceptance division 5 amplifies, detected the positive crest moment and export a high level signal by positive peak detector 6, be input to respectively or door 9 and single-chip microcomputer asynchronous counter 14, be input to or the signal of door 9 by or door 9, again by with door 12 to sending part 4, form the contrary circulation of ultrasound wave, establishing the contrary cycle frequency of its ultrasound wave is f _N, the contrary cycle period of ultrasound wave is T _NEvery circulation primary is amplified through acceptance division 5 and to be input to after positive peak detector 6 detects positive crest, outputs to the signal of single-chip microcomputer asynchronous counter 14, just by single-chip microcomputer asynchronous counter 14 countings once.In single-chip microcomputer asynchronous counter 14, insert the positive integer N (being about to the N value enrolls in single-chip microcomputer 14 programs) among the present invention's " prolongation passes apart from technology ", when making single-chip microcomputer asynchronous counter 14 count down to N, interruption is overflowed in generation, export a high level signal to bistable 18 and calculating section single-chip microcomputer 24, this signal make bistable 18 reset its output Q be low level, will with door 17, close the door with door 12, the contrary circulation of above-mentioned ultrasound wave is stopped, count section 21 also stops counting, make the contrary circulating sampling end cycle of ultrasonic flow meter, after this signal is input to the A of calculating section single-chip microcomputer 24, cause that single-chip microcomputer 24 enters interruption subroutine.

Sending part 1 drives downbeam ultrasonic emitting oscillator 28 emission ultrasound waves and passes mo-oo '-o ' m ' path, received by following current ultrasound wave pick-up dipole 29, again after acceptance division 2 amplifies, detected the positive crest moment and export a high level signal by positive peak detector 3, be input to respectively or door 7 and single-chip microcomputer asynchronous counter 13, be input to or the signal of door 7 by or door 7, again by with door 11 to sending part 1, form ultrasound wave along circulation, establishing its ultrasound wave is f along cycle frequency _s, ultrasound wave is T along cycle period _sEvery circulation primary, acceptance division 2 are amplified and are input to after positive peak detector 3 detects positive crest, output to the signal of single-chip microcomputer asynchronous counter 13, just by single-chip microcomputer asynchronous counter 13 countings once.In single-chip microcomputer asynchronous counter 13, insert the positive integer N among the present invention's " prolongation passes apart from technology " equally, when making single-chip microcomputer asynchronous counter 13 count down to N, interruption is overflowed in generation, export a high level signal to bistable 16 reset its output Q be low level, will be with door 15,11 close the door with door, above-mentioned ultrasound wave is stopped along circulation, and count section 20 also stops counting, makes ultrasonic flow meter along the circulating sampling end cycle.

Because the suitable circulating sampling cycle of ultrasonic flow meter is less than the contrary circulating sampling cycle, so it is the basic cycle that the ultrasonic flow meter sampling period also just should be got the contrary circulating sampling cycle, Here it is, and why single-chip microcomputer asynchronous counter 13 and single-chip microcomputer asynchronous counter 14 can both produce and overflow interruption, and have only single-chip microcomputer asynchronous counter 14 overflow the A that look-at-me is input to calculating section single-chip microcomputer 24 after, can cause that just single-chip microcomputer 24 enters the reason of interruption subroutine.

According to foregoing description, can find out:

1. the beginning and to cause by the I/O mouth B end output one high level square-wave signal of the single-chip microcomputer 27 of calculating section of each sampling period.

The end in 2. each sampling period produces after should the full N of single-chip microcomputer asynchronous counter 13 countings by sampling section to overflow to be interrupted and finishes.

3. count section 20 is counted the N in (72) formula that is, (77) formula, (78) formula ₁' (81)

4. count section 21 is counted the N in (72) formula that is, (77) formula, (78) formula ₂' (82)

5. the frequency f of high frequency time-base generator 19＞＞f _s, the frequency f of high frequency time-base generator 19＞＞f _N

$\frac{1}{N}\&CenterDot;f_s=f_{\mathrm{sc}}$ $\frac{1}{N}\&CenterDot;f_N=f_{\mathrm{Nc}}$ (N is the positive integer during the present invention " prolongs and passes apart from technology ")

f _Sc, f _NCShould satisfy (55) formula respectively $T<\frac{1}{2f_c}$ Or the empirical data table 0-1 in sampling period

Be f _Sc＞2f _cf _NC＞2f _c

(72) N in formula, (77) formula, (78) formula _τ", N _τ' must be worth after can accurately measuring, that is:

$\left.\begin{array}{c}{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}={n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\&CenterDot;N=(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})\&CenterDot;f\&CenterDot;N\\ {N_{\mathrm{\&tau;}}}^{\&prime;}={n_{\mathrm{\&tau;}}}^{\&prime;}\&CenterDot;N=(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})\&CenterDot;f\&CenterDot;N\end{array}\right\}---\left(83\right)$

(83) get behind the whole measured value of formula.N _τ", N _τ' value is used for single-chip microcomputer 24 programming uses.

(72) N in formula, (77) formula, (78) formula is except that single-chip microcomputer asynchronous counter 13 that should deposit sampling section in sampling process in and single-chip microcomputer asynchronous counter 14, also should with D, sin θ in N value and (72) formula, (77) formula, (78) formula three formulas, 2cos θ,

Carry out following calculating,

$\frac{\mathrm{ND}/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}---\left(84\right)$

(84) be used for after the formula overall calculation must be worth single-chip microcomputer 24 programming uses.

(77) in the formula To detected fluid is laminar flow (laminar flow) or Reynolds number R _eCalculated Q at＜2320 o'clock _tThe time, be used for single-chip microcomputer 24 programming uses.

(78) in the formula N can get by following column count:

By the 28th page of (2-36) formula of " flow measurement technology and instrument " book

$\stackrel{\&OverBar;}{u}=\frac{2n}{2n+1}\&CenterDot;{\stackrel{\&OverBar;}{u}}_D$

With the 24th page of (2-23) formula

$R_e=\frac{u\&CenterDot;L\&CenterDot;\mathrm{\&rho;}}{\mathrm{\&eta;}}(=\frac{\mathrm{\&rho;}\&CenterDot;\stackrel{\&OverBar;}{u}\&CenterDot;D}{\mathrm{\&eta;}})$

With (2-23) formula of this book of this book (2-36) formula substitution,

$R_e=\frac{\mathrm{\&rho;}\&CenterDot;D}{\mathrm{\&eta;}}\&CenterDot;\frac{2n}{2n+1}\&CenterDot;u_D---\left(85\right)$

By 26 page table 2-12 of this book, the relation of n and Reynolds number as can be known, when under the constant situation of D, ρ, η, R _eWhen known, n is corresponding known, that is to say the u in (85) formula _DCan only get unique value.Conversely speaking, if under the constant situation of D, ρ, η, u _DSize can determine the size of n, its u _DWith n is (also to be u one to one _DWith Be one to one), and u _DThe u of the present invention just (72) formula.

By (51) formula R _eIt≤2320 o'clock was laminar condition

By (85) formula u _DPromptly the n of the u correspondence of (72) formula or

Be used for single-chip microcomputer 24 programming uses.

(72), the Δ t in (77), (78) formula _iBe ultrasonic flow meter sampling period T _CFollowing calculating:

Δ t _i=N ₂' T+ (interrupt+forbid all interruption+single-chip microcomputer 24 output signals and latch N by single-chip microcomputer 24 responses ₁' and N ₂'+single-chip microcomputer 24 output signals begin sampling to count section 20 and 21 zero clearings+single-chip microcomputer 24 from I/O B end output signal) instruct the used time (86)

Above-mentioned data have been arranged, that is:

(81) several N of formula ₁'

(82) several N of formula ₂'

(83) several N of formula _τ", N _τ'

(84) number of formula $\frac{\mathrm{ND}/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}$

(85) several n of formula or

(86) several Δ t of formula _i

And constant

And f

Just can the single-chip microcomputer 24 of calculating section be programmed: make single-chip microcomputer 24 after entering interrupt routine, forbid all interruptions, latch the sampled value N of count section 20 and 21 from the F output signal ₁' and N ₂', to count section 20 and 21 zero clearings,, make sampling section enter the next sampling period from the C output signal from high level of I/O mouth B end output, read in several N of I/ O interface chip 22 and 23 respectively from D and E ₁' and N ₂' two numbers, and in single-chip microcomputer 24, finish Q of the calculating of (72) formula u and (77), (78) formula with above-mentioned existing all the other relevant each numbers _tCalculating, u and Q are calculated in institute _tValue deposits in single-chip microcomputer 24 nonvolatile memorys, changes master routine over to.Master routine is mainly finished open interruption and is sent apparent task.

The operation of ultrasonic flow meter, stop, the modification of above-mentioned relevant constant undertaken by the keyboard input command.

(embodiment 2)

Fig. 2 is the theory diagram of the embodiment 2 of ultrasonic flow meter of the present invention and principle and technology.

The ultrasonic flow meter of embodiment 2 comprises: sending part 1, acceptance division 2, positive peak detector 3, or door 7, monostable 8, with door 11, single-chip microcomputer asynchronous counter 13, with door 15, bistable 16, standard time-base generator 19, count section 20, I/O interface chip 22, single-chip microcomputer 24, keyboard and display interface chip 25, display part 26, keypad portion 27, fluid is flowed through and is managed 35, ultrasonic emitting pick-up dipole 38, ultrasonic emitting pick-up dipole 39, electronic analog swtich 40, electronic analog swtich 41.

The ultrasonic flow meter of embodiment 2 is broadly divided into three parts; Sampling section, calculating section and keyboard display part.

Sampling section is made jointly by the count section among Fig. 2 20 (asynchronous counter) and each circuit block of the left side thereof, and calculating section is made up of single-chip microcomputer 24, and sampling section is connected by I/O interface chip 22 with calculating section.

In the sampling section, the situation of the ultrasonic flow meter of standard time-base generator 19 and embodiment 1 is identical.

Sampling section is sampled or is not sampled, by the control assembly bistable 16 in the sampling section, monostable 8, with door 11, control (all with door or door all band application schmitt trigger) with door 15 or door 7, and these control assemblies selectively directly or indirectly are subjected to the control of sampling portion single-chip microcomputer asynchronous counter 13 and calculating section single-chip microcomputer 24.

The ultrasonic flow meter of embodiment 2, ultrasound wave is served as emission ultrasound wave task along circulation time by ultrasonic emitting pick-up dipole 39, and ultrasonic emitting pick-up dipole 38 is served as ultrasound wave and received task, this moment, a and the c of electronic analog swtich 40 connected a ' of electronic analog swtich 41 and c ' connection; And the contrary circulation time of ultrasound wave is served as emission ultrasound wave task by ultrasonic emitting pick-up dipole 38, and ultrasonic emitting pick-up dipole 39 is served as ultrasound wave and received task, and this moment, a and the b of electronic analog swtich 40 connected a ' of electronic analog swtich 41 and b ' connection.

Ultrasonic flow meter shown in Figure 2, because ultrasound wave is along circulation time and the contrary circulation time of ultrasound wave, the circuit of all having used identical sample unit to form, so ultrasonic flow meter has only timesharing to carry out along circulating sampling and the contrary circulating sampling of ultrasonic flow meter, this puts different with the ultrasonic flow meter of embodiment 1 shown in Figure 1.

Because ultrasonic flow meter is that timesharing is carried out along circulating sampling and the contrary circulating sampling of ultrasonic flow meter, so ultrasonic flow meter is inserted the positive integer of single-chip microcomputer asynchronous counter 13 " prolongation passes apart from technology " and is made as N ', can only be half of positive integer N of the ultrasonic flow meter of embodiment 1 " prolong and pass " of inserting single-chip microcomputer asynchronous counter 13 and 14, promptly apart from technology $N^{\&prime;}=\frac{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}{2},$ This puts different with the ultrasonic flow meter of embodiment 1 shown in Figure 1.

The ultrasonic flow meter of embodiment 2 is because its positive integer that " prolongs and pass apart from technology " $N^{\&prime;}=\frac{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}{2},$ So (83), (84) formula should be written as (83 ') and (84 ')

$\left.\begin{array}{c}{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}={n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\&CenterDot;N=(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})\&CenterDot;f\&CenterDot;\frac{N}{2}\\ {N_{\mathrm{\&tau;}}}^{\&prime;}={n_{\mathrm{\&tau;}}}^{\&prime;}\&CenterDot;N=(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})\&CenterDot;f\&CenterDot;\frac{N}{2}\end{array}\right\}---\left(83^{\&prime;}\right)$

$\frac{N^{\&prime;}D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}=\frac{\frac{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}{2}\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}---\left(84^{\&prime;}\right)$

This puts different with the ultrasonic flow meter of embodiment 1 shown in Figure 1.

The ultrasonic flow meter of embodiment 2 is because ultrasonic flow meter is that timesharing is carried out along circulating sampling and the contrary circulating sampling of ultrasonic flow meter, so the sampling period of ultrasonic flow meter

Δ t _i=(N ₁'+N ₂') T+2 * (single-chip microcomputer 24 responses are interrupted+forbidden all interruption+single-chip microcomputer 24 output signals and latch N ₁' and N ₂'+single-chip microcomputer 24 output signals begin sampling to count section 20 zero clearings+single-chip microcomputer 24 from I/O B end output signal) instruct the used time

(86′)

This puts different with the ultrasonic flow meter of embodiment 1 shown in Figure 1.

The ultrasonic flow meter of embodiment 2 shown in Figure 2, the beginning in each sampling period must be by first high level square-wave signal of I/O B end output of calculating section single-chip microcomputer 24, link simultaneously electronic analog swtich 40 and 41, make its connect for ultrasound wave along circulation or the contrary round-robin form of ultrasound wave.I/O mouth B holds this high level signal to be input to the set end and monostable 8 of bistable 16, be input to the asserts signal of bistable 16, make bistable 16 put the Q end and be high level, open with the door 15 and with door 11, make the high level pulse of standard time-base generator 19 with door 15, count by entering count section 20 with door 15, make with door 11: the high level of I/O mouth B end be input to monostable 8 make monostable 8 produce positive pulse output by or door 7 backs by being input to sending part 1 with door 11, activate sending part 1 and drive ultrasonic emitting pick-up dipole 39 or 38 emission ultrasound waves, and in ultrasonic emitting pick-up dipole 39 or 38 emissions hyperacoustic the time, ultrasonic emitting pick-up dipole 38 or 39 just receives ultrasound wave, detect positive crest constantly by being input to positive peak detector 3 after acceptance division 2 amplifications, export a high level to or door 7 and single-chip microcomputer asynchronous counter 13, be input to or door 7 signal by or door 7, again by being input to sending part 1 with door 11, make sampling section enter ultrasound wave along circulation or contrary circulation, ultrasound wave is along circulation or contrary circulation $N^{\&prime;}=\frac{N}{2}$ Inferior, full by single-chip microcomputer asynchronous counter 13 countings $N^{\&prime;}=\frac{N}{2}$ Overflow a high level signal, be input to bistable 16 and single-chip microcomputer 24A end, making bistable 16 Q that resets is low level, will close with door 11 with door 15.With closing of door 15 counting of count section 20 is stopped, ultrasonic flow meter is along circulating sampling cycle and the contrary circulating sampling end cycle of ultrasonic flow meter.The high level that is input to single-chip microcomputer 24A end causes that single-chip microcomputer 24 interrupts, and single-chip microcomputer 24 is finished the acceptance interruption, forbidden all interruptions, and single-chip microcomputer 24 latchs the count value N of count section 20 from the F output signal ₁' or N ₂', after C output signal zero clearing count section 20, subsequently, from second high level square-wave signal of I/O mouth B end output, link simultaneously electronic analog swtich 40 and 41, make its connect for and the opposite connection of ultrasound wave circulation last time, allow circuit finish the opposite ultrasonic flow meter sampling period.

By a pair of so opposite ultrasonic flow meter circulating sampling cycle and, ultrasonic flow meter sampling period of basic composition, later situation recursion.

From the above mentioned, the ultrasonic flow meter of embodiment 2 shown in Figure 2 can basis:

(81) N of formula ₁' (ultrasonic flow meter is along the 20 sampled value N that count of circulating sampling cycle inside counting portion ₁')

(82) N of formula ₂' (the contrary 20 sampled value N that count of circulating sampling cycle inside counting portion of ultrasonic flow meter ₂')

The N of (83 ') formula _τ", N _τ'

(84 ') formula $\frac{N^{\&prime;}D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}=\frac{\frac{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">N</figure-callout>}}{2}\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20051008869400351.png,C20051008869400361.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}---\left(84^{\&prime;}\right)$

(85) n of formula or

(86 ') formula Δ t _i=(N ₁'+N ₂') T+2 * (single-chip microcomputer 24 responses are interrupted+forbidden all interruption+single-chip microcomputer 24 output signals and latch N ₁' and N ₂+ single-chip microcomputer 24 output signals begin sampling to count section 20 zero clearings+single-chip microcomputer 24 from I/O B end output signal) instruct the used time

And constant

And f

Just can the single-chip microcomputer 24 of calculating section be programmed the same task that the ultrasonic flow meter that makes the ultrasonic flow meter of embodiment shown in Figure 22 finish embodiment shown in Figure 11 is finished.

(embodiment 3)

Fig. 3 is the theory diagram of the embodiment 3 of ultrasonic flow meter of the present invention (calorimeter) and principle and technology.

The ultrasonic flow meter of embodiment 3 (calorimeter) comprising: ultrasonic flow meter shown in Figure 1, temperature-sensing element (device) 32, temperature-sensing element (device) 33, amplifier 34, amplifier 36, A/D interface chip 37.

Structure, principle, technology, measuring process and the embodiment 1 described ultrasonic flow meter of the ultrasonic flow meter part in the ultrasonic flow meter of embodiment 3 (calorimeter) are identical.

Temperature-sensing element (device) 32 in the ultrasonic flow meter of embodiment 3 (calorimeter), temperature-sensing element (device) 33, amplifier 34, amplifier 36, A/D interface chip 37 and single-chip microcomputer 24, keyboard and display interface chip 25, display part 26, keyboard 27 are formed temperature gauge.

The fluid temperature (F.T.) that temperature gauge is located its place by temperature-sensing element (device) 32 and temperature-sensing element (device) 33 transfers this two signal of electric signal to respectively by after amplifier 34 and amplifier 36 amplifications, send into A/D interface chip 37 and carry out analog to digital conversion, digital signal after the conversion is input to single-chip microcomputer 24, according to these two numerals, fluid temperature (F.T.) by 24 pairs of temperature-sensing element (device)s 32 of single-chip microcomputer and place, temperature-sensing element (device) 33 places is calculated, and establishing its calculated value is t ₁And t ₂, and the N that samples in the ultrasonic flow meter in the moment of these two temperature value samplings and this machine ₁' and N ₂' moment unanimity (on the sequential before and after face mutually).

By the measured fluid volume Q of the ultrasonic flow meter (calorimeter) of embodiment shown in Figure 33 _tThe fluid temperature (F.T.) t measured with said temperature meter 2 ₁And t ₂, and fluid known density ρ, but the fluid between convection cell upstream temperature sensitive element 33 and the downstream temperature sensitive element 32 just flow through by fluid and to manage 35 outside heat dissipation capacity J _sOr caloric receptivity J _xCalculate.

Its calculating formula:

J _s＝cm _t(t ₂-t ₁)

＝c·Q _t·ρ·(t ₂-t ₁)

J _x＝cm _t(t ₁-t ₂)

＝c·Q _t·ρ·(t ₁-t ₂)

C is a detected fluid specific heat in the formula, m _tBe that volume is Q _tThe quality of fluid.

The principle formula of ultrasonic flow meter and principle thereof and technology and above-mentioned J according to the present invention _sOr J _x, single-chip microcomputer 24 is programmed, can realize detected fluid flow velocity u, flow Q _t, fluid J _sWith J _xMeasurement.

(embodiment 4)

Fig. 4 is the theory diagram of the embodiment 4 of ultrasonic flow meter of the present invention (calorimeter) and principle and technology.

The ultrasonic flow meter of embodiment 4 (calorimeter) comprising: ultrasonic flow meter shown in Figure 2 and temperature gauge shown in Figure 3.

The structure of the ultrasonic flow meter in the ultrasonic flow meter of embodiment 4 (calorimeter), principle, technology, measuring process and embodiment 2 described ultrasonic flow meters are identical; The structure of the temperature gauge among the embodiment 4, principle, technology, measuring process and embodiment 3 described temperature gauges are identical.

By the fluid measured volume Q of ultrasonic flow meter institute in the ultrasonic flow meter (calorimeter) of embodiment shown in Figure 44 _tThe fluid temperature (F.T.) t measured with the temperature gauge of this machine ₁And t ₂, and fluid known density ρ, the principle formula of ultrasonic flow meter and principle thereof and technology, above-mentioned J according to the present invention _sWith J _xThe principle formula, single-chip microcomputer 24 is programmed the same task that the ultrasonic flow meter (calorimeter) that makes the ultrasonic flow meter (calorimeter) of embodiment shown in Figure 44 finish embodiment shown in Figure 33 is finished.

Claims (2)

1, a kind of ultrasonic flow meter is measured the method for fluid flow, wherein ultrasonic flow meter comprises sampling section, calculating section, keyboard display part, it is characterized in that: by detecting ultrasonic flow meter respectively along circulating sampling in the cycle and the concussion number of times of the contrary circulating sampling cycle internal standard time-base generator (19) of ultrasonic flow meter, i.e. the sample count value N ' of sampling section first count section (20) and second count section (21) ₁, N ' ₂, in the single-chip microcomputer (24) of calculating section, the measuring principle of utilization ultrasonic flow meter flow velocity and flow and " prolong and pass apart from technology " are calculated, and realize the measurement of rate of flow of fluid and flow;

The measuring principle of described ultrasonic flow meter flow velocity and flow is:

(1) do not consider fluid flow through pipe (35) upside and the used time τ of downside, along the cycling circuit delay time T ' and contrary cycling circuit delay time T " time, the measuring principle formula of rate of flow of fluid u and the ultrasound wave velocity of wave c in fluid is (39), (41) formula:

$u=(\frac{1}{n_1}-\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(39\right)$

$c=(\frac{1}{n_1}+\frac{1}{n_2})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(41\right)$

n ₁: be that the ultrasound wave following current is propagated oo '=D/sin θ apart from required time t ₁The number of oscillation of interior standard time-base generator (19);

n ₂: be that the ultrasound wave adverse current is propagated uu '=oo '=D/sin θ apart from required time t ₂The number of oscillation of interior standard time-base generator (19);

D: be the flow through interior diameter of pipe (35) of fluid;

θ: the angle of its direction and rate of flow of fluid when being ultrasound wave following current propagation;

F: the oscillation frequency that is standard time-base generator (19);

(2) consider fluid flow through pipe (35) upside and the used time τ of downside, suitable cycling circuit delay time T ' and against the cycling circuit delay time T " time, the measuring principle formula of rate of flow of fluid u and the ultrasound wave velocity of wave c in fluid is (68), (69) formula:

$u=(\frac{1}{{n_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{n_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(68\right)$

$c=(\frac{1}{{n_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}+\frac{1}{{n_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(69\right)$

N ' ₁: be t ' ₁=t ₁The concussion number of times of the standard time-base generator (19) in+τ+τ ' time;

N ' ₂: be t ' ₂=t ₂+ τ+τ " the concussion number of times of the standard time-base generator (19) in the time;

N ' _τ: the concussion number of times that is the standard time-base generator (19) in τ+τ ' time;

N " _τ: " the concussion number of times of the standard time-base generator (19) in the time that is τ+τ;

To " prolong and pass " measuring principle formula (40), (42) formula and (72), (73) formula that measuring principle formula (39), (41) formula and (68), (69) formula obtain rate of flow of fluid and velocity of wave respectively of being applied to respectively apart from technology;

Wherein when not considering τ, τ ', τ " time, the measuring principle formula of rate of flow of fluid u and the ultrasound wave velocity of wave c in fluid is:

$u=(\frac{1}{N_1}-\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(40\right)$

$c=(\frac{1}{N_1}+\frac{1}{N_2})\&CenterDot;\frac{N\&CenterDot;D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(42\right)$

N ₁: be that the ultrasound wave following current is propagated oo '=D/sin θ apart from enlarging N times of back required time t ₁The number of oscillation of the standard time-base generator (19) in the N;

N ₂: be that the ultrasound wave adverse current is propagated uu '=oo '=D/sin θ apart from enlarging N times of back required time t ₂The number of oscillation of the standard time-base generator (19) in the N;

N: the positive integer N value that is " prolong and pass " apart from technology;

When considering τ, τ ', τ " time, the measuring principle formula of rate of flow of fluid u and the ultrasound wave velocity of wave c in fluid is:

$u=(\frac{1}{{N_1}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{N_2}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{\mathrm{ND}/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f---\left(72\right)$

$c=(\frac{1}{{N_1}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;}}+\frac{1}{{N_2}^{\&prime;}-{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{\mathrm{ND}/\sin \mathrm{\&theta;}}{2}\&CenterDot;f---\left(73\right)$

N ' ₁: be t ' ₁Time enlarges the doubly concussion number of times of its interior standard time-base generator (19) of back of N;

N ' ₂: be t ' ₂Time enlarges the doubly concussion number of times of its interior standard time-base generator (19) of back of N;

N ' _τ: be to enlarge the doubly concussion number of times of its interior standard time-base generator (19) of back of N τ+τ ' time;

N " _τ: being τ+τ, " time enlarges the doubly concussion number of times of its interior standard time-base generator (19) of back of N;

Described " prolong and pass apart from technology " is:

When ultrasonic flow meter is measured rate of flow of fluid u, prolong the propagation distance of ultrasound wave in fluid, be called for short " prolong and pass " apart from technology, the implementation method of this technology is respectively to (39) formula, (41) formula, (68) molecule of the equation of formula, (69) formula the right formula and denominator are with multiply by a positive integer N, make the propagation distance D/sin θ of ultrasound wave in limited caliber enlarge N doubly, thereby obtain measuring principle formula (40) formula, (42) formula, (72) formula, (73) formula of flow velocity and velocity of wave respectively;

And use (48), (49), (50), (51), (53), (52), (54), (85) formula to draw flow measurement principle formula (59), (60) formula and (77), (78) formula, that is:

When not considering τ, τ ', τ " time, flow measurement principle formula is:

Q _t: be that fluid is flowed through in the pipe (35) $S=\frac{\mathrm{\&pi;}{D}^2}{4}$ The fluid flow of elapsed time t on the represented S area;

Q _i: be Λ t _iIn time, $S=\frac{\mathrm{\&pi;}{D}^2}{4}$ Flow on the represented S area;

u _i: be Λ t _iThe mean flow rate of the fluid in the time on the above-mentioned S area;

π: be the garden frequency;

Δ t _i: be the ultrasonic flow meter sampling period;

In n be with the different positive numbers that change of the Reynolds number of detected fluid;

R _e: the Reynolds number that is detected fluid;

When considering τ, τ ', τ " time, flow measurement principle formula is:

" prolonging and pass apart from technology " the positive integer N that is taken advantage of can not unrestrictedly increase, should be subjected to the constraint of " Shannon's sampling theorem " determined (55) formula, determining of its positive integer N value should be determined T earlier in conjunction with reality from (55) formula, uses the Peak Flow Rate u when measuring rate of flow of fluid then from (8) formula _MaxDetermine t _2max, use (58) formula to get N again _MinPositive integer value be the positive integer N value of " prolong pass apart from technology ",

Wherein (55) formula, (8) formula, (58) formula and (48), (49), (50), (51), (53), (52), (54), (85) formula are as follows:

$T<\frac{1}{2f_c}---\left(55\right)$

T: be " Shannon's sampling theorem " determined sampling period;

f _c: be the mean flow rate u of fluid on pipe (35) the diameter D that flows through _DThe highest frequency of time dependent simulating signal;

$\left.\begin{array}{c}{t}_1=\frac{o{o}^{\&prime;}}{c+u\cos \mathrm{\&theta;}}\\ t_2=\frac{o{o}^{\&prime;}}{c-u\cos \mathrm{\&theta;}}\end{array}\right\}---\left(8\right)$

$N_{\min }=\frac{T}{t_{2\max }}---\left(58\right)$

t _2max: be the corresponding u of u _MaxThe time correspondence t ₂Maximal value;

N _Min: N _MinPositive integer value be the positive integer N value of " prolong pass apart from technology ";

$Q_i=\stackrel{-}{u_i}\&CenterDot;\frac{\mathrm{\&pi;}{D}^2}{4}\&CenterDot;\mathrm{\&Delta;}{t}_i---\left(48\right)$

$Q_t=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Q}_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\stackrel{-}{u_i}\&CenterDot;\frac{\mathrm{\&pi;}{D}^2}{4}\&CenterDot;\mathrm{\&Delta;}{t}_i,(i=\mathrm{1,2,3},\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n)---\left(49\right)$

$R_e=\frac{\mathrm{\&rho;}\&CenterDot;{\stackrel{-}{u}}_i\&CenterDot;D}{\mathrm{\&eta;}}---\left(50\right)$

ρ: the density that is detected fluid;

η: be the detected fluid kinetic viscosity or the title coefficient of viscosity;

When

R _e≤ 2320 o'clock (51)

$\stackrel{-}{u_i}=\frac{3}{4}u---\left(53\right)$

When

R _e＞2320 o'clock (52)

$\stackrel{-}{u_i}=\frac{2n}{2n+1}u---\left(54\right)$

Wherein:

$R_e=\frac{\mathrm{\&rho;}\&CenterDot;D}{\mathrm{\&eta;}}\&CenterDot;\frac{2n}{2n+1}\&CenterDot;u_D---\left(85\right)$

u _D=u: be flow through mean flow rate on pipe (35) interior diameter of fluid;

The derivation of the measuring principle formula of described ultrasonic flow meter flow velocity and velocity of wave is:

When not considering τ, τ ', τ " time, that is:

c＝f·λ (11)

$\frac{u}{\mathrm{\&lambda;}}=n^{*}---\left(12\right)$

λ: be the ultrasound wave wavelength of ultrasound wave when the f frequency;

n ^*Be the multiple of u to λ;

$c+u\cos \mathrm{\&theta;}=\mathrm{f\&lambda;}+n^{*}\mathrm{\&lambda;}\cos \mathrm{\&theta;}$

$=f(1+\frac{n^{*}\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}---\left(13\right)$

$c-u\cos \mathrm{\&theta;}=\mathrm{f\&lambda;}-n^{*}\mathrm{\&lambda;}\cos \mathrm{\&theta;}$

$=f(1-\frac{n^{*}\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}---\left(14\right)$

$f(1+\frac{n^{*}\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}=f{\mathrm{\&lambda;}}_1---\left(15\right)$

$f(1-\frac{n^{*}\cos \mathrm{\&theta;}}{f})\mathrm{\&lambda;}=f{\mathrm{\&lambda;}}_2---\left(16\right)$

λ ₁: be the wavelength of ultrasound wave downbeam in fluid when propagating;

λ ₂: be the wavelength of ultrasound wave countercurrent direction in fluid when propagating;

2ucosθ＝f(λ ₁-λ ₂) (19)

2c＝f(λ ₁+λ ₂) (34)

With (13), (14), (15), (16) formula substitution formula (8) formula, obtain (20), (21) formula:

$\left.\begin{array}{c}{t}_{1}f=\frac{o{o}^{\&prime;}}{{\mathrm{\&lambda;}}_1}\\ t_{2}f=\frac{o{o}^{\&prime;}}{{\mathrm{\&lambda;}}_2}\end{array}\right\}---\left(20\right)$

$\left.\begin{array}{c}{t}_{1}f=n_1\\ t_{2}f=n_2\end{array}\right\}---\left(21\right)$

(20), (21) formula substitution (19), (34) formula are got measuring principle formula (39), (41) formula of flow velocity and velocity of wave;

When considering τ, τ ', τ " time, that is:

With the t in (63) formula ₁, t ₂In substitution (21) formula, get (64) formula,

Wherein (63) formula, (64) formula are as follows:

$\left.\begin{array}{c}{t}_1={t_1}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;}\\ t_2={t_2}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;\&prime;}\end{array}\right\}---\left(63\right)$

$\left.\begin{array}{c}{n}_1=t_{1}f=({t_1}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;})f={t_1}^{\&prime;}f-(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})f\\ n_2=t_{2}f=({t_2}^{\&prime;}-\mathrm{\&tau;}-{\mathrm{\&tau;}}^{\&prime;\&prime;})f={t_2}^{\&prime;}f-(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})f\end{array}\right\}---\left(64\right)$

If (64) in the formula

$\left.\begin{array}{c}{t_1}^{\&prime;}f={n_1}^{\&prime;}\\ {t_2}^{\&prime;}f={n_2}^{\&prime;}\end{array}\right\}---\left(65\right)$

$\left.\begin{array}{c}(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})f={n_{\mathrm{\&tau;}}}^{\&prime;}\\ (\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})f={n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\end{array}\right\}---\left(66\right)$

With (65) formula, (66) formula substitution (64) formula,

$\left.\begin{array}{c}{n}_1={n_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}\\ n_2={n_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\end{array}\right\}---\left(67\right)$

With (67) formula difference substitution (39) formula and (41) formula, get measuring principle formula (68), (69) formula of flow velocity and velocity of wave, equation the right molecule, denominator get (70) formula with multiply by positive integer N in (68), (69) formula,

$\left.\begin{array}{c}u=(\frac{1}{{n_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}-\frac{1}{{n_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}})\&CenterDot;\frac{N}{N}\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2\cos \mathrm{\&theta;}}\&CenterDot;f\\ c=(\frac{1}{{n_1}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;}}+\frac{1}{{n_2}^{\&prime;}-{n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}})\&CenterDot;\frac{N}{N}\&CenterDot;\frac{D/\sin \mathrm{\&theta;}}{2}\&CenterDot;f\end{array}\right\}---\left(70\right)$

(70) in the formula, establish

$\left.\begin{array}{c}{n_2}^{\&prime;}N={N_2}^{\&prime;}\\ {n_1}^{\&prime;}N={N_1}^{\&prime;}\\ {n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}N={N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\\ {n_{\mathrm{\&tau;}}}^{\&prime;}N={N_{\mathrm{\&tau;}}}^{\&prime;}\end{array}\right\}---\left(71\right)$

With (71) formula substitution (70) formula, get fluid-velocity survey principle formula (72) formula and velocity of wave measuring principle formula (73) formula;

N in flow velocity, velocity of wave measuring principle formula (72), (73) formula, flow measurement principle formula (77), (78) formula " _τ, N ' _τUse with being used for single-chip microcomputer (24) programming behind the whole measured value of (83) formula;

$\left.\begin{array}{c}{N_{\mathrm{\&tau;}}}^{\&prime;\&prime;}={n_{\mathrm{\&tau;}}}^{\&prime;\&prime;}\&CenterDot;N=(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;\&prime;})\&CenterDot;f\&CenterDot;N\\ {N_{\mathrm{\&tau;}}}^{\&prime;}={n_{\mathrm{\&tau;}}}^{\&prime;}\&CenterDot;N=(\mathrm{\&tau;}+{\mathrm{\&tau;}}^{\&prime;})\&CenterDot;f\&CenterDot;N\end{array}\right\}---\left(83\right)$

Δ t in flow measurement principle formula (59), (60), (77), (78) formula _iNot only should satisfy (56) formula

Δt _i≤T (56)

And should calculate by (86) formula;

Δ t _i=N ' ₂T _B+ (all interruption+single-chip microcomputers (24) are interrupted+forbid in single-chip microcomputer (24) response

Output signal latchs N ' ₁And N ' ₂+ single-chip microcomputer (24) output signal begins sampling to first, second count section (20), (21) zero clearing+single-chip microcomputer (24) from I/O mouth B end output signal) instruct the used time (86)

T _BBe the oscillation period of standard time-base generator (19).

2, ultrasonic flow meter as claimed in claim 1 is measured the method for fluid flow, it is characterized in that: the each sampling of ultrasonic flow meter begins and should be caused by the I/O mouth B end output one high level square-wave signal of the single-chip microcomputer (24) of calculating section, and the end of the each sampling of ultrasonic flow meter produces after should the full N of second singlechip asynchronous counter (14) counting by sampling section to overflow to be interrupted and finish; Sampling section sampling or do not sample, by control assembly first trigger flip-flop (16) of sampling section, second trigger flip-flop (18), first monostalbe trigger (8), second monostalbe trigger (10), first with door (11), second with door (12), the 3rd with door (15), the 4th with door (17), first or (7) and second or (9) control; The positive integer N that puts is " prolong and pass apart from technology " described N in the first single-chip microcomputer asynchronous counter (13) and the second singlechip asynchronous counter (14).

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