Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-01-19
2001-07-24
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S090000, C384S107000
Reexamination Certificate
active
06265798
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a motor, and especially a motor having a magnetic bearing that incurs no rotation wear.
BACKGROUND OF THE INVENTION
In most prior art motors, the positioning of the rotation shaft is achieved by a heatproof washer or a metallic C-ring. A conventional self-lube bearing fan motor, as shown in
FIG. 1
, comprises: a base
11
, a stator
12
, a rotor
13
, a bearing
14
, an elastic washer
15
, and a C-ring
16
.
The base
11
is located at the central location of a fan frame
10
. The base
11
and the fan frame
10
are integrally formed. In the central location of the base
11
is provided a bearing seat
111
. The stator
12
is telescopically fitted on the bearing seat
111
and is fixed relative to the base
11
. The stator
12
includes a plurality of coils
121
and a plurality of silicon steel sets
122
. The bearing
14
is a self-lube bearing fitted in the bearing seat
111
of the base
11
. The rotor
13
includes a hollow cylinder
130
having an open end. The outer wall of the cylinder
130
engages with a fan blade set
134
and on the inner wall of the cylinder
130
is provided a magnet
131
. At the central location of the cylinder
130
is provided a rotation shaft
132
. A groove
133
is formed near the lower end of the rotation shaft
132
. The rotation shaft
132
is received by the bearing
14
. The elastic washer
15
is telescopically fitted on the rotation shaft
132
at an upper location thereof to provide an elastic buffer. The C-ring
16
is engaged in the groove
133
near the lower end of the rotation shaft
132
so that rotation shaft
132
is prevented from being disengaged from the base
11
.
From the above description, it can be know that in the prior art motor, the C-ring
16
is used to axially position the rotation shaft
132
of the rotor
13
so that when the rotor
13
rotates after the excitation of the coil
121
and generates airflow F
1
, the C-ring
16
prevents the bearing
14
from disengaging from the base
111
due to the force F
2
exerted on the fan blade set
134
.
The positioning of the rotation shaft in the aforementioned prior art motor involves the following drawbacks:
1. When the motor operates, the contact wear and friction between the C-ring
16
and bearing
14
are incurred and the life of the motor will be reduced.
2. The friction between the C-ring
16
and the bearing
14
incurs noises or varied rotation speeds.
3. The rotor
13
and the stator
12
are designed with a magnetic bias. However, when the rotor
13
rotates, the rotation shaft
132
is moved by an external force and the equilibrium position of the rotor relative to the stator is determined by the external force. This results in a big problem in motor design.
SUMMARY OF THE INVENTION
An object of the invention is to provide a motor having a magnetic bearing that utilizes a magnetic force to adjust the position of the rotation shaft to achieve a non-contact axial positioning effect and to avoid contact wear when the motor operates.
Another object of the invention is to provide a motor having a magnetic bearing that utilizes a magnetic force to adjust the radial position of the rotation shaft to achieve a non-contact radial positioning effect and to avoid contact wear when the motor operates.
Yet another object of the invention is to provide a motor having a magnetic bearing that utilizes a magnetic force to avoid the insufficiency of the original magnetic bias so that a stationary equilibrium position of the rotor can be achieved when the motor operates.
To achieve the above-mentioned objects, a motor having a magnetic bearing in accordance with the invention comprises a base formed with a bearing seat; a stator fixed to the base; a rotor provided with a rotation shaft and rotatable with respect to the stator by magnetic forces generated from excitation; a bearing fixed to the bearing seat of the base for receiving the rotation shaft of the rotor; and a magnetic element pair including a first element and a second element. The first element is telescopically interference-fitted on the rotation shaft, the second element is fixed relative to the bearing seat and letting the rotation shaft insert therethrough, and a magnetic force is generated between the first element and the second element. The magnetic force pushes the rotation shaft toward or out of the base.
When the above-mentioned motor rotates, an external force acts on the rotor in a direction and a magnetic force between the magnetic element pair is utilized to counteract the external force so that the axial positioning of the rotation shaft can be achieved and the contact wear can be avoided. In addition, the insufficiency of the magnetic bias between the rotor and the stator can be avoided and the rotor can be kept in a stationary equilibrium position when the motor operates.
Furthermore, a magnetic bearing can be used to replace the bearing of the above-mentioned motor for radially positioning the rotation shaft. The magnetic bearing is provided in the bearing seat and comprises at least one magnetic element pair including a first element and a second element. The first element is telescopically interference-fitted on the rotation shaft and the second element is fixed relative to the bearing seat and lets the rotation shaft insert therethrough. Each of the first element and the second element is formed with a tapered contact surface, and a magnetic force is generated between the first element and the second element. The first element and the second element can achieve not only an axial positioning effect but also a radial positioning effect.
REFERENCES:
patent: 3899223 (1975-08-01), Baermann
patent: 5280208 (1994-01-01), Komura et al.
patent: 5561335 (1996-10-01), Dunfield et al.
patent: 5821655 (1998-10-01), Tokushima et al.
patent: 6057620 (2000-05-01), Chen et al.
Chuang Te-Tsai
Huang Wen-hsi
Lin Kuo-Cheng
Tsai Min-shi
Delta Electronics , Inc.
Lam Thanh
Ramirez Nestor
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