Variable speed motor with tapped starting winding

Details Variable speed motor with tapped starting winding Variable speed motor with tapped starting winding

2000-08-21

2002-07-02

Waks, Joseph (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S179000, C310S189000, C310S114000, C310S134000

Reexamination Certificate

active

06414412

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a variable speed motor, more particularly to a variable speed motor with a tapped starting winding.
2. Description of the Related Art
Referring to
FIGS. 1A and 1B
, a variable speed motor for a ceiling fan in accordance with U.S. Pat. No. 4,841,188 is shown to include a motor body
5
, a run coil
1
, and a starting winding
2
. The motor body
5
, such as a stator, has an axis
510
, and a plurality of coil mounting parts
511
that extend radially and that are angularly spaced apart relative to the axis
510
, thereby forming a plurality of radial slots thereamong. The run coil
1
and the starting winding
2
are mounted on the coil mounting parts
511
of the motor body
5
. As illustrated, the run coil
1
spans substantially all of the coil mounting parts
511
of the motor body
5
. In addition, the coil mounting parts
511
are grouped into three adjacent clusters, each of which is spanned by a respective one of first, second and third speed-changing coils
205
,
206
,
207
of the starting winding
2
. The starting winding
2
further includes a set of medium speed taps
203
a
,
203
b
, and a set of low speed taps
204
a
,
204
b.
The run coil
1
has first and second coil terminals
101
,
102
, and is to be connected across an AC power source
4
. The first speed-changing coil
205
has a first coil terminal
201
, and a second coil terminal provided with one of the medium speed taps
203
a
. The second speed-changing coil
206
has a first coil terminal provided with the other one of the medium speed taps
203
b
, and a second coil terminal provided with one of the low speed taps
204
a
. The third speed-changing coil
207
has a first coil terminal provided with the other one of the low speed taps
204
b
, and a second coil terminal
202
. A capacitor
3
connects the second coil terminal
202
of the third speed-changing coil
207
to the second coil terminal
102
of the run coil
1
.
During high-speed operation of the motor, the first coil terminal
201
of the first speed-changing coil
205
is connected to the first coil terminal
101
of the run coil
1
, the medium speed taps
203
a
,
203
b
interconnect the first and second speed-changing coils
205
,
206
in series, and the low speed taps
204
a
,
204
b
interconnect the second and third speed-changing coils
206
,
207
in series. As such, the series combination of the first, second and third speed-changing coils
205
,
206
,
207
and the capacitor
3
is connected in parallel to the run coil
1
and to the AC power source
4
.
Referring to
FIGS. 2A and 2B
, during medium-speed operation of the motor, the medium speed tap
203
a
connects the second coil terminal of the first speed-changing coil
205
to the first coil terminal
101
of the run coil
1
, while the other medium speed tap
203
b
connects the first coil terminal of the second speed-changing coil
206
to the first coil terminal
201
of the first speed-changing coil
205
. The low speed taps
204
a
,
204
b
interconnect the second and third speed-changing coils
206
,
207
in series. As such, the series combination of the second and third speed-changing coils
206
,
207
and the capacitor
3
is connected in parallel to the series combination of the first speed-changing coil
205
and the run coil
1
and to the AC power source
4
.
Referring to
FIGS. 3A and 3B
, during low-speed operation of the motor, the medium speed taps
203
a
,
203
b
interconnect the first and second speed-changing coils
205
,
206
in series. The low speed tap
204
a
connects the second coil terminal of the second speed-changing coil
206
to the first coil terminal
101
of the run coil
1
, while the other low speed tap
204
b
connects the first coil terminal of the third speed-changing coil
207
to the first coil terminal
201
of the first speed-changing coil
205
. As such, the series combination of the third speed-changing coil
207
and the capacitor
3
is connected in parallel to the series combination of the first and second speed-changing coils
205
,
206
and the run coil
1
and to the AC power source
4
.
Due to the arrangement of the starting winding
2
, the directions of current flow through the first, second and third speed-changing coils
205
,
206
,
207
can be maintained when changing between high-speed and medium-speed operations, and when changing between medium-speed and low-speed operations, thereby resulting in noise reduction.
During the medium-speed and low-speed operations of the motor, at least one of the first and second speed-changing coils
205
,
206
is connected in series to the run coil
1
. As such, the amounts of currents flowing through the first, second and third speed-changing coils
205
,
206
,
207
of the starting winding
2
tend to differ from each other during the medium-speed and low-speed operations. Because the first, second and third speed-changing coils
205
,
206
,
207
span only a respective cluster of the coil mounting parts
511
of the motor body
5
, uniform magnetic line distribution at the coil mounting parts
511
can not be maintained during the medium-speed and low-speed operations of the motor, which can affect stability and balance, and which can arise in the generation of vibration and noise.
SUMMARY OF THE INVENTION
Therefore, the main object of the present invention is to provide a variable speed motor with a tapped starting winding that is capable of overcoming the aforesaid drawback of the prior art.
According to this invention, a variable speed motor comprises a motor body, a run coil and a starting winding. The motor body has an axis, and a plurality of coil mounting parts that extend radially and that are angularly spaced apart relative to the axis. The run coil is mounted on the coil mounting parts. The starting winding includes first, second and third speed-changing coils mounted on the coil mounting parts, a set of first taps provided respectively on first and second coil terminals of the first speed-changing coil, a set of second taps provided respectively on first and second coil terminals of the second speed-changing coil, and a set of third taps provided respectively on first and second coil terminals of the third speed-changing coil. Each of the first, second and third speed-changing coils spans an angular length relative to the axis that is substantially equal to that spanned by the run coil.
Preferably, each of the run coil and the first, second and third speed-changing coils of the starting winding spans substantially all of the coil mounting parts of the motor body.


REFERENCES:
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patent: 5012148 (1991-04-01), Vithayathil
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patent: 6008560 (1999-12-01), Becerra
patent: 6133702 (2000-10-01), Noble et al.

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