Rotor of a Built-in Motor

1. Field of the Invention

This invention relates to a rotor of a built-in motor. More specifically, this invention relates to an improvement applicable to the structure of a rotor of a built-in motor, for the purpose of enabling the shaft of the built-in motor to be readily removed from the core of the built-in motor.

2. Description of the Related Art

It is not necessarily difficult to fit the shaft of an electric motor with the core of the electric motor, because various convenient methods, such as force fit, shrinkage fit, etc., are available. It is not necessarily easy, however, to remove the shaft of an electric motor from the core of the electric motor, because application of a considerable magnitude of heat, pressure or the like is generally required for this purpose.

Since a built-in motor has a stator which is mounted, with a flange, on a machine which is driven by the built-in motor, and since it has a rotor which is fitted with the shaft of the machine which is driven by the built-in motor, the core is inclined to be frequently required to be removed from the shaft.

Therefore, a structure which allows a shaft to be readily removed from a core is desirable for a built-in motor.

The object of this invention is to provide a rotor of a built-in motor having a structure which allows the shaft to be readily removed from the core part thereof, whenever it is required.

To achieve the above mentioned object, a rotor of a built-in motor in accordance with this invention is provided:

a shaft (1) having a stepped part (11);

a sleeve (2) having a hollow space (21) arranged to cover the stepped part (11) and a hydraulic pressure supply means (22) and being fitted with the shaft (1) having the stepped part (11); and

a core (3) being fitted with the sleeve (2).

In other words, a rotor of a built-in motor in accordance with this invention has a core (3) which is fitted with a sleeve (2) which is further fitted with a shaft (1), remaining a hollow space (21) therein at a location to cover a stepped part (11) of the shaft (1). The sleeve (2) has a hydraulic pressure supply means (22) for supplying hydraulic pressure into the hollow space (21) which is asymmetrical from side to side (or which has one end (23) whose area is larger than that of the other end (24)). Therefore,the core (3) and sleeve (2) can readily be removed from the shaft (1) by applying hydraulic pressure to the hollow space (21) employing the above mentioned hydraulic pressure supply means (22), because it exerts a thrust in the direction of the shaft (1) based on the above mentioned asymmetry of the above mentioned sleeve (2) (or based on the difference in area of the one end (23) and the other end (24) of the above mentioned sleeve (2)).

FIG. 1 is a cross-sectional view showing the assembled position of the rotor of a built-in motor of one embodiment of this invention; and

FIG. 2 is a cross-sectional view showing the rotor of a built-in motor of the embodiment of FIG. 1 being disassembled in which the sleeve carrying the core is removed from the shaft.

Referring to FIG. 1, a shaft 1 (which is usually the shaft of a machine driven by the built-in motor, not shown in the drawings) has a stepped part 11. A sleeve 2 has a hollow space 21 therein. The one end 23 of the sleeve 2 is fitted with the shaft 1 on the right side of the stepped part 11 as shown in the drawing (or the one end 23 of the sleeve 2 is fitted with the shaft 1 at a location at which the diameter of the shaft 1 is smaller), and the other end 24 of the sleeve 2 is fitted with the shaft on the left side of the stepped part 11 as shown in the drawing (or the one end 24 of the sleeve 2 is fitted with the shaft 1 at a location at which the diameter of the shaft 1 is larger). As a result, the sleeve 2 is asymmetrical from side to side. The sleeve 2 has a hydraulic pressure supply means 22 for supplying hydraulic pressure into the hollow space 21 of the sleeve 2.

A rotor core 3 having a set of windings 4 is permanently fitted on the sleeve 2. In other words, there is little chance for the core 3 to be removed from the sleeve 2.

When this rotor is assembled, the core 3 is fitted with the sleeve 2. Then, the sleeve 2 is heated, before it is pushed to the left and if fitted with the shaft 1 with the shrinkage fit, as shown in the drawing.

Referring to FIG. 2, when this rotor is disassembled (or when the sleeve 2 is removed from the shaft 1), hydraulic pressure with a high pressure of approximately 700 Kg/cm.sup.2 is applied into the hollow space 21, employing the hydraulic pressure supply means 22.

An application of this magnitude of hydraulic pressure causes the sleeve 2 to be elastically deformed, and the friction beteween the both ends 23 and 24 of the sleeve 2 and the shaft 1 is decreased due to a decrease in the pressure between the sleeve 2 and the shaft 1. As a result, even a little difference in the area existing between the both ends 23 and 24 of the sleeve 2, readily causes the sleeve 2 to be shifted in the direction of an arrow shown in the drawing (in the direction from the end whose area is smaller to the end whose area is larger) and resultantly to be removed from the shaft 1. In this way, the core 3 can readily be removed from the shaft 1.

The foregoing description has clarified that this invention has successfully provided a rotor of a built-in motor having a structure which allows the shaft to be readily removed from the core thereof, wheneven it is required.

Although the foregoing description was presented referring to a specific embodiment, this is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as other embodiments of this invention, will be apparent to persons skilled in the art upon reference to the description of this invention. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of this invention.