Patent EP0772026A2 successfully refreshed from Google Patents.
EP0772026A2
Expired / Lapsed
EP
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Improved gas mass flow metering valve
Assignee: Nuovo Pignone SpA
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Filing: 1996-10-29
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Granted: —
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Expires: 2016-10-29
Abstract
Abstract A new gas flow control valve which also enables the mass flow to be measured, which valve, using a flow straightener in the valve entry duct, a tube for prolonging said entry duct into the valve, a valving element passage port with suitably radiused edges and a flow stabilizer in the valve exit duct, and positioning the upstream and downstream pressure taps of the valve immediately upstream of said flow straightener and downstream of said stabilizer respectively, enables the flow rate to be controlled not from the formulas traditionally used for valve dimensioning but from formulas derived from the more accurate formulas used for calculating mass flow with standard members of fixed restriction type. Preferred embodiments of the valve components are also described.
Inventors
- 👤 Lorenzo Bergamini
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 11:01
CPC Classifications
G; G01; G01F; G01F7/00; G01F7/005; G01F1/00; G01F1/05; G01F1/34; G01F1/36; G01F1/40; G01F1/42; Y; Y10; Y10T; Y10T137/00; Y10T137/7722; Y10T137/7758; Y10T137/7759; Y10T137/776; Y10T137/7761
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
198 words
A gas mass flow metering valve, comprising an entry duct, an exit duct, a valving element provided with a passage port, a seal ring cooperating with said valving element, said ring being made to rotate by an operating means, and means for measuring the pressure upstream and downstream of the valve and the valve gas temperature, characterised in that into said entry duct there is inserted a flow straightener, immediately downstream of which, within the valve body, there are positioned the valve upstream pressure taps, said entry duct being prolonged by a prolongation tube into the interior of the valving element nearly as far as the convergence region in correspondence with said exit port through an aperture in the valving element opposite said exit port, said valving element exit port being formed with an edge geometry consisting of a converging curvature arranged to convey the gas flow in such a manner as to cause it to assume a direction substantially parallel to the axis of the exit duct, which is provided in its interior with a flow stabilizer, the valve downstream pressure taps being positioned within the valve upstream of said stabilizer, in proximity to said exit port.
Claim 2
Dependent Claim
21 words
A valve as claimed in claim 1, characterised in that said flow straightener is a straightener of honeycomb or multi-tube type.
Claim 3
Dependent Claim
83 words
A valve as claimed in claim 1, characterised in that said flow or jet stabilizer consists of two inclined walls forming substantially a C section dividing said exit duct into three sectors, namely a central sector and two lateral flow recirculation sectors, said walls being joined together internally by a third wall connecting together said lateral flow recirculation sectors, the two said walls being provided on their inner facing surfaces with corresponding inclined deflectors defining ports which gradually grow towards the valve exit.
Claim 4
Dependent Claim
85 words
A valve as claimed in claim 1, characterised in that said operating means for rotating the seal ring consists of a lever pivoted on the valve body, its longer arm being moved by a pin rigid with the valving element, the movement of the shorter arm being transmitted to the seal ring by a non-return device formed from a preloaded spiral spring wound about and forced onto an appropriate housing in said seal ring, said spring being connected to said short arm of the lever.
Claim 5
Dependent Claim
34 words
A valve as claimed in claim 1, characterised in that said converging curvature of the valving element exit port is substantially a circular arc of radius equal to the width of said exit port.
Claim 6
Dependent Claim
256 words
A valve as claimed in claim 1, characterised by enabling the flow rate to be measured and controlled by the formula: G = φA 2 p 1 0 β 1/k √[(η 12 /z 1 RT 1 0 )(2K/[k-1])(1-β (k-1)/k]) where: G = mass flow A 2 = restricted section area z = compressibility factor R = gas elastic constant k = isentropic evolution constant η 12 = correction coefficient taking account of any deviation of the real gas behaviour from the hypothesis of polytropic evolution at constant exponent φ = discharge coefficient: it includes the effects of flow non-unidimensionality and depends on the degree of opening and on the Reynolds number T 1 0 = total inlet gas temperature calculated from: T 1 0 = T 1 (1+[(k-1)/2K][G 2 zRT 1 /A 1 2 kp 1 2 ]) where: A 1 = tube area at entry p 1 = static pressure at entry T 1 = absolute temperature p 1 0 = total gas pressure at entry: p 1 0 = p 1 (T 1 0 /T 1 ) k/(k-1) β = pressure ratio. The greater of the expressions: p 2 /[p 1 0 (1+(ε p2 -1)M 2 )] and [2/(k+1)] k/(k-1) where: p 2 = pressure measured in vena contracta ε p2 = correction coefficient for vena contracta pressure measurement under critical conditions. This can be determined experimentally as a function of the angle of opening of the valving element M 2 = Mach number in vena contracta, where: M 2 = √[(2/(k-1))(β (1-k)/k -1)]
Claim 7
Dependent Claim
33 words
A valve as claimed in claim 1, characterised in that the inner walls of said valving element have a shape obtained as the envelope of the spaces generated by rotating the interior tube.
References Cited (Backward Citations)
No citation records indexed.
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