Flow measuring device

Claim 1

A flow measuring device according to the principle of the Karman vortex path which comprises: a vortex generating choke body having a prismatic part of trapezoidal cross-section of a height h, said prismatic part of trapezoidal cross-section having a first side of a length a and a section side of a length b in parallel alignment with said first side, and said choke body having a slab-like extension of a length l and a maximum width d projecting away from said second side; and pressure pickups positioned inside said prismatic part of the choke body, such that said pressure pickups can measure the periodic pressure variations which are generated by the vortex separation, said pressure pickups comprising at least two chambers positioned in the side walls of said prismatic part of trapezoidal cross-section, each of said chambers is covered by an element constructed of a pressure deflectable material, and each of said chambers is connected in a pressure conducting manner with transducers for converting the deflections of said deflectable element into electrical signals which are proportional to said deflections; wherein: b is less than a; the ratio of the height h of said trapezoidal cross-section to the length a of the first side is a value of from about 0.5 to about 1; The ratio of the length l of said slab like extention projecting away from said second side b to the length of the first surface a is a value of from about 0.5 to about 1; the ratio of the sum of the height h of said trapezoidal cross-section and the length l of said slab-like extention to the length of the first side a is a value of from about 1.2 to about 1.8; the ratio of the length of said second side b to the length of said first side a is a value of from about 0.5 to about 0.7; and the ratio of the width d of said slab-like extension to the length a of said first side is a value of from about 0.15 to about 0.35.