Patent ID: 7033147

Claim:
A centrifugal fluid pump assembly which includes a housing having a fluid inlet and a fluid outlet, an impeller rotatable within said housing for feeding fluid by centrifugal force upon rotation thereof, and a motor for rotating said impeller, comprising: a motor current flow rate-related data storage section for storing, for a plurality of different predetermined viscosities, predetermined viscosity-related flow rate data formed from a plurality of motor current flow rate relation data at a plurality of different impeller rotational speeds at predetermined fluid viscosity; a fluid measurement data inputting section; an impeller rotational speed measurement function or an impeller rotational speed calculation function; a motor current measurement function; a flow rate calculating section for calculating a fluid flow rate using 1) a fluid viscosity value inputted to said fluid measurement data inputting section or calculated from a fluid measurement data inputted to said fluid measurement data inputting section, 2) an impeller rotational speed value obtained by said impeller rotational speed measurement function or impeller rotational speed calculation function, 3) a measured motor current obtained by said motor current measurement function and 4) the data stored in said motor current flow rate-related data storage section; wherein said motor current flow rate-related data storage section comprises at least a first predetermined viscosity-related flow rate data storage function for storing a plurality of data regarding the motor current and the flow rate at a plurality of impeller rotational speeds at a first predetermined fluid viscosity, a second predetermined viscosity-related flow rate data storage function for storing a plurality of data regarding the motor current and the flow rate at a plurality of impeller rotational speeds at a second predetermined fluid viscosity, and a third predetermined viscosity-related flow rate data storage function for storing a plurality of data regarding the motor current and the flow rate at a plurality of impeller rotational speeds at a third predetermined fluid viscosity; a specific gravity inputting section or specific gravity calculating function; and a measured motor current correcting function for correcting the measured motor current using a specific gravity inputted by said specific gravity inputting section or calculated by said specific value calculating function.