Electrically driven motors and pumps having such motors

Abstract

A motor, possibly for a pump, has a housing, a first member disposed within the housing and mounted on an inner wall of the housing, and a second member rotatably disposed within the housing and having a rotary shaft. A thrust bearing is mounted within the housing in order to support a first end of the rotary shaft in an axial direction of the rotary shaft. A core and coils wound around the core are provided on one of the first and second members. A set of magnets is provided on the other of the first and second members. The core and the set of magnets are positioned such that a magnetic force is produced in an area where a magnetic flux is generated between the core and the set of magnets. The magnetic force causes the second member to move toward the thrust bearing.

Description

[0001] This application claims priority to Japanese patent application serial number 2003-344431, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to electrically driven motors and pumps having such motors. [0004] 2. Description of the Related Art [0005] Various types of electrically driven motors are known. For example, Japanese Laid-Open Patent Publication No. 2000-102210 teaches a brush-less electrically driven motor having a housing, a stator, a rotor, magnets, a thrust bearing, and a spring. The rotor has a rotor shaft that is rotatably supported by the housing. The magnets are provided on the rotor and oppose the stator via a predetermined space. The thrust bearing is mounted to the housing and supports the one end of the rotor shaft with respect to a thrust direction. The spring biases the rotor in a direction toward the thrust bearing, so that the one end of the rotor...

AI Technical Summary

Benefits of technology

[0007] It is accordingly an object of the present invention to teach improved techniques for minimizing the number of parts and the number of assembly steps of electrically driven motors.

[0009] Therefore, it is not necessary to incorporate a spring in order to bias the rotary shaft toward the thrust bearing. As a result, the number of parts and the number of assembly steps of the motor can be reduced.

[0010] In another aspect of the present teachings, the core and the set of magnets are offset from each other in the axial direction of the rotary shaft. This allows the biasing force to be easily produced by primarily determining the position of the core relative to the set of magnets.

[0018] In another aspect of the present teachings, the motor further includes an electric control circuit electrically connected to the coils in order to control the supply of current to the coils. The electrical control circuit is disposed within a substantially closed space formed within the first end cover. The substantially closed space reliably prevents the possible short-circuiting or breakage of the electrical connection.

Problems solved by technology

Because the motor of the above publication requires a spring to bias the rotor toward the thrust bearing, there has been a problem with the relatively large number of parts and the relatively large number of assembly steps for assembling the motor.

These problems have been a limitation in attempts to downsize the motors.

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