Electric pump

Abstract

An electric pump may comprise a pump case (110, 150) having a pump chamber. An impeller 143 may be rotatably disposed within the pump chamber. The impeller 143 may include a magnetized cylindrical portion 145. A stator 133 may be disposed opposite to the cylindrical portion 145 of the impeller 143. The stator 133 may drive the impeller 143 by applying magnetic forces to the cylindrical portion 145 of the impeller 143. A shaft 146 may be formed integrally with the impeller 143. One end of the shaft 143 may be rotatably supported with respect to the pump case.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to Japanese Patent Application numbers 2006-22284, filed on 31 January with the JPO, the contents of which are hereby incorporated by reference into the present application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an electric pump used to circulate cooling water to cool an automobile engine or an inverter or the like.[0004]2. Description of the Related Art[0005]The known electric pump includes a pump case. A pump chamber is formed in the pump case. An impeller is disposed within the pump chamber. The impeller includes a magnetized cylindrical portion. A bearing is formed integrally in the center of the impeller, and a shaft is inserted into the bearing. One end of the shaft is fixed in the pump casing (in other words, the shaft is supported cantilevered from the pump case). A stator is disposed outside the pump case to drive the impeller. The external ...

AI Technical Summary

Benefits of technology

[0007]It is an object of the present teachings to provide an electric pump capable of reducing the vibrations of the impeller about the shaft, and controlling the occurrence of unpleasant noise.

[0009]In this electric pump, the shaft is rotatably supported with respect to the pump case, and the shaft is fixed to the impeller. Therefore, there is no relative motion between the impeller and the shaft, and this measure on its own suppresses vibrations of the impeller about the shaft. In other words, in a structure in which the impeller is installed on a shaft fixed to the pump case so that the impeller can rotate with respect to the shaft, there is a clearance between the shaft and the impeller, and the clearance promotes oscillation of the impeller about the shaft. In this electric pump, the impeller is fixed to the shaft, and there is no clearance between the two, so it is possible to suppress vibrations of the impeller about the shaft. In this way, it is possible to suppress the occurrence of unusual sounds.

[0010]In another aspect of the present teachings, an electric pump capable of reducing the amount of impeller wear, and improving the impeller durability is provided. In other words, when the impeller is rotating, the fluid drawn into the pump chamber flows in between the impeller and the pump casing. Therefore, the contact force between the impeller and the pump casing is reduced, so impeller wear does not become a problem. However, if air or foreign matter is mixed into the fluid drawn into the pump chamber, the fluid pressure acting on the impeller fluctuates. Therefore, there are occasions when the impeller is strongly forced against pump casing, so impeller wear becomes a problem. If the impeller wears, the durability of the impeller is reduced.

[0012]In this electric pump, the fluid drawn into the pump chamber can flow in the grooves formed in the lower end surface of the bearing. Therefore, the friction force generated between the bearing of the impeller and the pump casing is reduced. Therefore, wear of the impeller is suppressed, and the durability of the impeller can be improved.

Problems solved by technology

However, if air or foreign matter is mixed into the fluid drawn into the pump chamber, the fluid pressure acting on the impeller fluctuates.

Therefore, there are occasions when the impeller is strongly forced against pump casing, so impeller wear becomes a problem.

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