RU2476732C1 - Flow transmitter - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: flow transmitter includes a housing with supply and discharge channels, a restricting element forming high and low pressure chambers together with the housing, and bellows; besides, bellows are attached to the housing with their end face in the discharge channel zone; restricting element is made in the form of a cylindrical shell installed on the other end face of the bellows and forming a restricting slot together with the housing bottom, the opening value of which is determined by a formula.

EFFECT: improving flow measurement accuracy of hydraulic liquid flowing in large amounts in pipelines regardless of density of the mixture composition.

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Description

The invention relates to the field of engineering hydraulics and can be used to measure the flow of liquid, gas and their mixture in the pipelines of hydraulic and pneumatic systems, as well as to measure the amount of transported product through oil and gas pipelines.

A known flow sensor containing a bellows placed in a chamber with liquid, and rigidly connected with a fixed partition having a hole, and a nozzle directing a controlled fluid flow into the hole. SU 201688 A, 09/08/1967.

The known flow sensor does not provide a sufficiently high accuracy of flow measurement in large quantities in pipelines with a diameter of over 500 mm

The closest technical solution (prototype) to the claimed invention is a flow sensor (US 3103119 A, 09/10/1963), comprising a housing with inlet and outlet channels, a throttling element forming a high and low pressure chamber in the housing, and a bellows.

A disadvantage of the known flow sensor is the dependence of the determined flow rate on the density of the hydraulic fluid.

The objective of the invention is to improve the accuracy of measuring the flow rate of hydraulic fluid flowing in large quantities in the pipelines and does not depend on the density of the flowing composition of the mixture.

EFFECT: increased accuracy of measuring the flow rate of hydraulic fluid flowing in large quantities in pipelines and not depending on the density of the flowing composition of the mixture.

The problem is solved and the technical result is achieved by the fact that the flow sensor comprises a housing with inlet and outlet channels, a throttling element forming a high and low pressure chamber with the housing, and a bellows, the new one being that the bellows is attached to the housing with its end in the zone of the outlet channel, the throttling element is made in the form of a cylindrical shell mounted on the other end of the bellows and forming a throttling gap with the bottom of the housing, the opening value of which is determined by the formula

x = ρVg / C,

where x is the gap is the magnitude of the opening of the throttling gap, m;

ρ is the density of the hydraulic fluid, kg / m ³ ;

V is the volume of liquid, m ³ ;

g is the acceleration of gravity, m / s ² ;

C is the rigidity of the bellows, N / m.

The drawing shows a flow sensor in section.

The flow sensor includes a housing 1 with a supply channel 2 and a discharge channel 3, a throttling element forming with the housing 1 of the chamber 4, 5, respectively, high and low pressure, and a bellows 6. The bellows 6 is attached to the housing 1 with its end 7 in the area of the discharge channel 3, the throttling element is made in the form of a cylindrical shell 8 mounted on the other end 9 of the bellows 6 and forming a throttling gap 11 with the bottom 10 of the housing 1.

The fluid flow rate Q _dr (m ³ / s) through the throttle (throttle gap) is determined by the formula

Q _dr = μf _u · √2ΔP / ρ,

where µ is the flow coefficient;

f _u - the area of the working passage, m ² ;

f _u = πdx;

d is the diameter of the shell hole, m;

x - clearance - the magnitude of the opening of the throttling gap, m;

ΔР - differential pressure of the liquid, Pa;

ΔP = P ₁ -P ₂ ;

P ₁ - pressure in the inlet channel, Pa;

P ₂ - pressure in the outlet channel, Pa.

Squaring both sides of the equation, we get

Q _dr ² / µ ² π ² d ² x ² = 2ΔPρ,

.DELTA.P (πD ^{2/4-πd 2/4)} -ρVg = Cx

where D is the largest diameter of the bellows, m;

d is the diameter of the shell hole, m

If P ₁ ≈P _2, then

Cx = ρVg, then

x = ρVg / C,

V _beg = (πD ² H / 4-πd ² H / 4),

V _con = (πD ^{2/4-πd 2/4)} · (Hx),

where V _beg - the initial volume;

V _con - final volume.

The flow sensor operates as follows.

The working hydraulic fluid enters through the supply channel 2 to the high-pressure chamber 4 of the housing 1. The fluid flow passing through the bends of the bellows is deformed in the horizontal direction, equalizing the flow rate, and approaches the throttling slit 11 formed by the bottom 10 of the housing 1 and the end face of the shell 8. The working fluid acts on the end face 9 of the bellows 6, deflecting it in the direction of increasing the throttling gap 11. The size of the gap 11 depends on the flow rate, the larger it is, the smaller the difference and, accordingly, opening (x).

This, in turn, will determine the error under the assumptions made. Losses (ΔР) are determined by the resistance of the gap 11. With proper selection, they will be minimal. The implementation of the sensitive element of the differential pressure measuring system in the form of the end face 9 of the bellows 6 allows to obtain the identity of the flow characteristics regardless of the density of the working fluid, which increases the accuracy of the measurements. Having passed the throttle slit 11, the working hydraulic fluid enters the low pressure chamber 5 and from it into the discharge channel 3 and then into the hydraulic system.

Claims (1)

A flow sensor comprising a housing with inlet and outlet channels, a throttling element forming a high and low pressure chamber with the housing, and a bellows, characterized in that the bellows is attached to the housing with its end in the area of the outlet channel, the throttling element is made in the form of a cylindrical shell mounted at the other end of the bellows, and forming a throttling gap with the bottom of the body, the opening value of which is determined by the formula x = ρVg / C, where
x - clearance - the magnitude of the opening of the throttling gap, m;
ρ is the density of the hydraulic fluid, kg / m ³ ;
V is the volume of liquid, m ³ ;
g is the acceleration of gravity, m / s ² ;
C is the rigidity of the bellows, N / m.