BACKGROUND OF THE INVENTION
This invention relates to flow meters of the turbine variety wherein a rotor is turned by the fluid being measured. The turbine rotor turns at a velocity proportional to the rate of flow. The vanes of the rotor passing through the magnetic field of a pickoff coil generate a pulsating signal in the pickoff coil at a frequency that is proportional to the flow rate.
DESCRIPTION OF THE PRIOR ART
Prior art turbine type flow meters typically comprise a single rotor with its pickoff coil together with various means for the preconditioning of the flow pattern ahead of the turbine. While such prior art turbine type flow meters are superior to most other types of flow meters, they still leave considerable room for improved performance in terms of accuracy, linearity, minimization of initial calibration requirements, and especially in terms of measurement range.
SUMMARY OF THE INVENTION
This invention relates to turbine type flow meters incorporating means ahead of the main turbine rotor for optimally shaping and directing the flow pattern as the fluid enters the main rotor.
It is, therefore, one object of the present invention to provide a turbine type flow meter that provides improved accuracy relative to prior art turbine type flow meters.
Another object of this invention is to provide a turbine type flow meter that exhibits improved accuracy over a wider range of fluid flow rates without resort to excessively high revolutions per minute at the maximum rate of flow, such excessively high revolutions per minute being undesirable as they adversely affect bearing life of the turbine flow meter.
A still further object of this invention is to provide a turbine type flow meter that provides improved linearity over the total measurement range.
A still further object of this invention is to provide such an improved turbine type flow meter in a form that eliminates the need for initial calibrations involving the tweaking or filing of rotor blades, bending of straightener vanes, etc. to obtain wide range linearity.
A still further object of this invention is to achieve such improved performance through the incorporation of an auxiliary, oppositely turning rotor ahead of or upstream from the main rotor, the auxiliary rotor serving as the primary means for appropriately directing the flow pattern of the fluid as it enters the main rotor.
Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize his invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.