Electric fluid pump

Abstract

An electric fluid pump includes an upper housing having a fluid inlet and outlet. An impeller is seated within the upper housing for pumping fluid between the inlet and the outlet. The impeller includes at least one magnet secured thereto. A lower housing mates with the upper housing. The lower housing has an upper wall for closing the upper housing and a shaft extending from the upper wall for rotatably supporting the impeller. A stator is seated within the lower housing and spaced from the impeller by the upper wall. The stator includes a plurality of pillars supporting a winding of coils for producing a magnetic field to energize the magnet and rotate the impeller, and a plurality of top plates covering each of the coils and spaced apart by a predetermined gap for maintaining the magnetic field between the stator and the impeller. An end cap closes the stator within the lower housing.

Description

FIELD OF THE INVENTION [0001] The invention relates to a pump driven by a brushless direct current (DC) motor. More particularly, the invention relates to any fluid pump system using DC brushless motor technology to drive coolant (for water pumps) or oil (for engine and transmission pumps). BACKGROUND OF THE INVENTION [0002] The most common pump accessory arrangement found in automobiles utilizes the engine rotation to drive a shaft via a belt connection between a driving pulley (connected to the crankshaft) and a driven pulley. These belts and pulleys are cumbersome, bulky, noisy, and transfer power (torque) inefficiently. Another disadvantage is that these pumps have their output dictated by the rotational speed of the engine. Certain accessories that are coupled to the engine, such as the coolant and oil pumps, must be over-sized, because the pump output must deliver a minimum flow amount of fluid at low engine speeds. At higher engine speeds, such as those experienced under norm...

AI Technical Summary

Benefits of technology

[0015] In an alternate embodiment, the motor housing is a matrix of a polymer and filling compound that gives the polymer good thermal characteristics to allow heat generated in the stator to be transferred through the housing to the coolant or fluid being pumped.

[0016] One embodiment implements a stator design in which the core has expanded top surfaces with tapered or bevelled ends. The tapered ends provide a method to increase the “effective” gap between the stator poles. This allows the stator phases to be closer together resulting in a dramatically reduced physical gap and greatly reducing the “cogging” effect. This feature allows stronger magnets to be used resulting in greater output power for a given size.

[0018] In an alternate embodiment, the rotor and impeller form a unitary body, in order to reduce the number of parts.

[0019] All embodiments eliminate the need for the conventional aluminum plate, resulting in the minimization of drag created by eddy currents generated by the rotating magnets. This results in greater efficiency in converting electrical energy into mechanical power. Furthermore, the removal of the aluminum plate allows the motor housing to be molded as a single unit.

Problems solved by technology

These belts and pulleys are cumbersome, bulky, noisy, and transfer power (torque) inefficiently.

Another disadvantage is that these pumps have their output dictated by the rotational speed of the engine.

This leads to poor efficiencies and increased power losses due to the requirement for a bypass.

However, while aluminum has excellent heat transfer characteristics, it also decreases motor efficiency.

This results in a loss of efficiency when converting electrical energy to mechanical power.

These posts are limited in size resulting in a “cogging” effect in which the rotor wants to rest in specific positions.

This limited size sets restrictions regarding the strength of the permanent magnets and thus limits the maximum output power of the motor for any given motor size.

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