Water current meter

• US 4,258,568 A
• Filed: 07/19/1979
• Issued: 03/31/1981
• Est. Priority Date: 07/19/1979
• Status: Expired due to Term

• Current Assignee: Boris P. Sukhov, Reinder Boetes
• Original Assignee: Boris P. Sukhov, Reinder Boetes
• Inventors: Sukhov, Boris P., Boetes, Reinder
• Primary Examiner(s): MYRACLE, JERRY
• Application Number:
  US06/058,644
• Time in Patent Office: 621 Days
• Field of Search: 73/170 A, 73/189
• US Class Current: 73/170.11
• CPC Class Codes: B63B 22/18 having means to control attitude or position, e.g. reaction surfaces or tether
• CPC Class Codes: G01P 5/02 by measuring forces exerted by the fluid on solid bodies, e.g. anemometer
• CPC Class Codes: G01P 7/00 Measuring speed by integrating acceleration measuring travelled distance by double integration of acceleration G01C21/16

Abstract

A self recording meter for recording water currents is described. The current meter comprises a housing having a vertical axis, three accelerometers each having a sensitive axis mounted at 90° to each other within the housing wherein the sensitive axis of one of the accelerometers is coincident with the housing vertical axis, and the other axes are substantially horizontal, a magnetic compass disposed within the housing for measuring an angle defined between magnetic North and the sensitive axis of one of the substantially horizontal accelerometers, a depth sensor, and circuitry for emitting electronic signals from the accelerometers, compass and depth sensor indicating magnitude of horizontal current relative to depth, direction of horizontal current relative to depth, and magnitude and direction of vertical current relative to depth.

The meter is releasably secured to a weight such that it drops to the water bottom where a release mechanism separates the weight from the meter housing and a switching circuit concurrently activates the meter electronic circuitry such that current measurements are made as the meter rises to the surface. The meter electronic circuitry is deactivated upon the meter reaching the surface at which time a flashing light and radio beacon are activated.

Current measurements are recorded on a cassette tape for subsequent interpretation.

Claims

1. A water current meter comprising, in combination:

a housing having a vertical axis, three accelerometers each having a sensitive axis mounted at 90°

to each other within said housing wherein the sensitive axis of one of said accelerometers is coincident with said housing vertical axis, and the other axes are substantially horizontal, a magnetic compass disposed within the housing for measuring an angle defined between magnetic North and the sensitive axis of one of said substantially horizontal accelerometers, a depth sensor, and circuitry for emitting electronic signals from said accelerometers, compass and depth sensor indicating magnitude of horizontal current relative to depth, direction of horizontal current relative to depth, and magnitude and direction of vertical current relative to depth.

2. A water current meter as claimed in claim 1, in which said circuitry includes a signal conditioning system for converting electronic signals from the accelerometers, compass and depth sensor to binary coded decimal signals, a digital recorder, and a multiplexer for receiving said converted signals and transmitting said converted signals to the recorder.

3. A water current meter as claimed in claim 2, in which said housing has positive buoyancy, said current meter additionally comprising a releasable weight for imparting negative buoyancy to the meter whereby said meter upon deployment sinks to the bottom of the water, means for releasing said weight upon impact with the bottom whereby the meter housing floats to the surface, and switching means for activating the meter circuitry upon release of the weight and deactivating the said circuitry upon the meter housing reaching the surface.

4. A water current meter as claimed in claim 3, in which said switching means comprises a permanent magnet secured to the releasable weight and a pair of reed switches in series, one of which is normally open and the other normally closed, operably mounted within the housing opposite to and controlled by the said permanent magnet, whereby said normally-open reed switch closes upon release of the weight and the permanent magnet, a relay operable by said closing of the reed switch having a normally-open switch in a circuit parallel to the closing reed switch which closes to maintain the meter circuit activated, a switching transistor operably connected to the depth sensor and adapted to function as a switch for a second relay wherein said second relay is activated when the meter housing reaches the surface to deactivate the meter circuit.

5. A water current meter as claimed in claim 4, in which said current meter additionally comprises a signalling unit including a flashing light and radio beacon activated by the second relay upon the meter housing reaching the surface.

6. A water current meter as claimed in claim 5, in which said housing has a symmetrical shape relative to its vertical axis and has a high drag coefficient and low mass.

7. A water current meter as claimed in claim 6, in which the housing has an elongated cylindrical shape.

8. A water current meter as claimed in claim 7, in which said cylindrical housing has a planar disc concentric with the housing extending therefrom perpendicular to the vertical axis of the housing for increasing vertical drag.

9. A water current meter as claimed in claim 8, in which said planar disc has a cylindrical sleeve formed on the periphery thereof concentric therewith for increasing vertical and horizontal drag.

10. A water current meter as claimed in claim 7, in which the releasable weight has a plunger rod slidably mounted in an axial hole formed in the weight in alignment with the vertical axis of the housing and projecting downwardly from the weight, a disc secured to the lower free end of the rod for engaging the bottom, an inverted frusto-conical head having a peripheral groove secured to the upper end of the rod, and a plurality of spring-loaded release plungers radially disposed in the weight equiangularly about the said head in engagement with the peripheral recess at one end and in engagement with the meter housing at the opposite end, whereby upward axial movement of the plunger rod upon contact with the bottom permits the said release plungers to be biased inwardly releasing the weight from the meter housing.

11. A water current meter as claimed in claim 6, in which said housing has a spherical shape.

12. A water current meter as claimed in claim 11, in which said spherical housing has a hollow cylindrical extension formed at the lower portion thereof co-axial with the vertical axis of the housing, and a release mechanism for the weight comprising a cylindrical weight having an axial hole in alignment with the vertical axis of the housing, a plunger rod slidably mounted in said hole projecting downwardly from the weight, a disc secured to the lower free end of the rod for engaging the bottom, and a plurality of hooks pivotally mounted on the weight about the periphery thereof adapted to grip the cylindrical extension and operable by the plunger rod whereby upward axial movement of the plunger rod upon contact with the bottom releases the said hooks from the cylindrical extension.

13. A water current meter as claimed in claim 6, in which said housing has a transparent top cover and an antenna mounted on said top cover, said antenna having a spring extension at one end securing the antenna to the top cover and a circular disc at the other free end.

14. A method of measuring water currents comprising the steps of sinking to the water bottom a buoyant meter housing releasably secured to a weight, said housing having a vertical axis and containing three accelerometers each having a sensitive axis mounted at 90°

to each other within said housing wherein the sensitive axis of one of said accelerometers is coincident with said housing vertical axis, and the other axes are substantially horizontal, a magnetic compass disposed within the housing for measuring an angle defined between magnetic North and the sensitive axis of one of said substantially horizontal accelerometers, a depth sensor, and circuitry for emitting electronic signals from said accelerometers, compass and depth sensor indicating magnitude of horizontal current relative to depth, direction of horizontal current relative to depth, and magnitude and direction of vertical current relative to depth, releasing said meter housing from the weight and concurrently activating a flashing light and radio beacon.