Current meter or flow meter

Claim 2

A flow meter comprising: a cylindrical object immersed in fluid whose velocity is to be measured and producing Karman vortices therein; a purge fluid reservoir; purge fluid conduit means connected to said reservoir and extending into said cylindrical object and terminating in openings on opposite side surfaces of said cylindrical object, said openings being formed to be substantially perpendicular to the flow direction of said fluid, said purge fluid conduit means conducting purge fluid from said purge fluid reservoir to flow out of said openings of said cylindrical object, the pressure of said purge fluid in said reservoir being greater than the static pressure of said fluid surrounding said cylindrical object; and velocity detecting means mounted in said purge fluid conduit means and detecting the variations of velocity of said purge fluid in said purge fluid conduit means which is indicative of the flow velocity of said fluid.

Claim 3

A flow meter as claimed in claim 1 wherein said purge fluid conduit means comprises a pair of tubes which extend into said cylindrical object and are joined together and connected to said reservoir through a common conduit and said velocity detecting means is mounted in one of said tubes.

Claim 4

A flow meter as claimed in claim 1 wherein openings in said cylindrical object are a plurality of openings on each side thereof aligned in its axial direction.

Claim 5

A flow meter as claimed in claim 1 wherein said openings in said cylindrical object are a pair of slits on each side thereof and extending in the longitudinal direction of said cylindrical object.

Claim 6

A flow meter as claimed in claim 1 in which said purge fluid conduit means have restrictors mounted therein.

Claim 7

A flow meter as claimed in claim 1 in which said purge fluid is air.

Claim 8

A flow meter as claimed in claim 1 in which said purge fluid is a liquid and the pressure of said liquid is approximately equal to atmospheric pressure.

Claim 9

A flow meter comprising: a cylindrical object to be immersed in fluid whose velocity is to be measured and producing Karman vortices in said fluid; a purge fluid reservoir; purge fluid in said reservoir; at least two openings formed in said cylindrical object on opposite sides thereof and said openings formed to be substantially perpendicular to the flow direction of said fluid; a pair of cavities formed in said cylindrical object on opposite sides thereof and said two openings communicating therewith; a partition wall between said cavities; an aperture formed in said partition wall; a pair of tubes connected to said reservoir and respectively communicating with said cavities; purge fluid supplied to said tubes which passes through said aperture and the pressure of said purge fluid in said reservoir being greater than the static pressure of said fluid surrounding said cylindrical object; and velocity detecting means for measuring the flow of said purge fluid.

Claim 10

A flow meter comprising: a cylindrical object to be immersed in fluid whose velocity is to be measured and producing Karman vortices in said fluid; a purge fluid reservoir; purge fluid in said reservoir; at least two openings formed in said cylindrical object on opposite sides thereof and said openings formed to be substantially perpendicular to the flow direction of said fluid; a pair of cavities formed in said cylindrical object on opposite sides thereof and said two openings communicating therewith; a partition wall between said cavities; an aperture formed in said partition wall; a pair of tubes connected to said reservoir and respectively communicating with said cavities; purge fluid supplied to said tubes which passes through said aperture and the pressure of said purge fluid in said reservoir being greater than the static pressure of said fluid surrounding said cylindrical object; and velocity detecting means for measuring the flow of said purge fluid.

Claim 11

A flow meter as claimed in claim 8 wherein said velocity detecting means is mounted in one of said tubes for detecting the variations of velocity of said purge fluid.

Claim 12

A flow meter as claimed in claim 8 wherein said velocity detecting means is mounted in said aperture.

Claim 13

A flow meter comprising: a cylindrical object to be immersed in fluid whose velocity is to be measured and for producing Karman vortices in said fluid; a purge fluid reservoir for supplying purge fluid to purge said cylindrical object, the pressure of the purge fluid in said reservoir being greater than the static pressure of said fluid surrounding said cylindrical object; a pipe with one end connected to said purge fluid reservoir and feeding said purge fluid out of an opening in said cylindrical object to purge at least one side surface of said cylindrical object and said opening formed to be substantially perpendicular to the flow direction of said fluid; and a fluid displacement detecting element mounted in said pipe means for detecting the variations of velocity of said purge fluid.

Claim 14

A flow meter comprising: a cylindrical object to be immersed in fluid whose velocity is to be measured and for producing Karman vortices in said fluid; a purge fluid reservoir for supplying purge fluid to purge said cylindrical object, the pressure of the purge fluid in said reservoir being greater than the static pressure of said fluid surrounding said cylindrical object; a pipe with one end connected to said purge fluid reservoir and feeding said purge fluid out of an opening in said cylindrical object to purge at least one side surface of said cylindrical object and said opening formed to be substantially perpendicular to the flow direction of said fluid; and a fluid displacement detecting element mounted in said pipe means for detecting the variations of velocity of said purge fluid.

Claim 15

A flow meter as claimed in claim 11 in which said cylindrical object has provided therein a plurality of axially aligned openings adjacent said openings on at least one side surface thereof and said plurality of openings formed to be substantially perpendicular to the flow direction of said fluid.

Claim 16

A flow meter as claimed in claim 12 wherein said opening in said cylindrical object is a slit extending in the axial direction and formed to be substantially perpendicular to the flow direction of said fluid.

Claim 17

A flow meter as claimed in claim 11 in which said cylindrical object has formed therein two cavities, a partition wall between said cavities, an aperture formed in said partition wall, and said opening comprises a pair of groups of aligned openings in the wall of said cylindrical object on opposite sides thereof and formed to be substantially perpendicular to the flow direction of said fluid, said group of openings of one side communicating with the group of openings on the other side through said cavities and said aperture and said pipe feeding purge fluid into one of said openings, cavities or aperture so that it flows out of said groups of aligned openings.

Claim 18

A flow meter as claimed in claim 14 in which said fluid displacement detecting element is mounted in said aperture.