Electric motor and fan unit employing the same

Abstract

A ring-shaped member is secured to a shaft of a motor between a portion of the shaft connected to a rotor and a sleeve accommodating the shaft and impregnated with lubricating oil. The ring-shaped member is coated with a repellent agent repelling the lubricating oil. An outer diameter of the ring-shaped member at its sleeve side, i.e., a first outer diameter is larger than that at the opposite side, i.e., a second outer diameter. A shaft-retaining portion is provided between the connected portion of the shaft and the ring-shaped member. A diameter of the hole is larger than the first outer diameter and smaller than the second outer diameter. At least one of the ring-shaped member and the shaft-retaining portion is elastically deformable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a fan unit using an electric motor according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view of the fan unit of FIG. 1.

FIG. 3 is a perspective view of a housing of the fan unit of FIG. 1, with a circuit board and a stator attached thereto.

FIG. 4 is a cross-sectional view of the fan unit of FIG. 1, while a rotating part and a stationary part are separated from each other.

FIG. 5 shows the stator of the fan unit of FIG. 1, when seen from above.

FIG. 6 is a partial, enlarged cross-sectional view of a ring-shaped member, a shaft-retaining portion and components around them in the fan unit of FIG. 1.

FIGS. 7A to 7F are cross-sectional views showing modified examples of the ring-shaped member in the fan unit of FIG. 1.

Claims

1. A motor comprising: a shaft rotatable around a rotation axis and connected in its connection part to a rotor;a sleeve impregnated with lubricating oil, surrounding the shaft except for the connection part of the shaft, and supporting the shaft in a rotatable manner;a hollow cylindrical portion having an open end and accommodating the sleeve;a ring-shaped member secured around the shaft between the connection part of the shaft and the sleeve and coated with a repellent agent repelling the lubricating oil, an outer peripheral surface of the ring-shaped member facing the hollow cylindrical portion, the ring-shaped member having a first outer diameter at its sleeve side and a second outer diameter at its connection-part side larger than the first outer diameter; anda shaft-retaining portion defining a hole therein and provided on the hollow cylindrical portion to be located between the connection part of the shaft and the ring-shaped member, a diameter of the hole being larger than the first outer diameter and smaller than the second outer diameter of the ring-shaped member, whereinat least one of the ring-shaped member and the shaft-retaining portion is elastically deformable.

2. A motor according to claim 1, wherein the ring-shaped member is tapered toward the sleeve in such a manner that the first outer diameter is smaller than the second outer diameter.

3. A motor according to claim 1, wherein the outer peripheral surface of the ring-shaped member is stepped.

4. A motor according to claim 1, further comprising a stator including a core, a coil wound around the core, and an insulator insulating the core from the coil, the stator being secured to an outer peripheral surface of the hollow cylindrical portion, wherein the shaft-retaining portion is formed by a part of the insulator.

5. A motor according to claim 1, wherein the ring-shaped member is a pressed metal member.

6. A motor according to claim 5, wherein a layer of the repellent agent repelling the lubricating oil is formed on a surface of the ring-shaped member by immersing the ring-shaped member in the repellent agent.

7. A motor according to claim 1, wherein a sleeve side face of the ring-shaped member is concave in such a manner that the sleeve side face gets close to the sleeve radially outward.

8. A fan unit comprising the motor according to claim 1 and an impeller generating an air flow by its rotation, wherein the impeller is connected to the shaft of the motor directly or via a rotor hub.