Reciprocating motor

Details Reciprocating motor Reciprocating motor

2002-11-25

2004-12-21

Lam, Thanh (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Linear

C310S017000

Reexamination Certificate

active

06833637

ABSTRACT:

TECHNICAL FIELD
The present invention relates a reciprocating motor, and more particularly, to an improved reciprocating motor in which the width of an entrance of an opening where a winding coil is positioned, that is, the interpole distance is minimized, the space of the opening is maximized to reduce the amount of a pricy permanent magnet to be used, its output is heightened and its structure is simplified to be compact.
BACKGROUND ART
Generally, a motor is an instrument for converting an electric energy to a kinetic energy. There are two types of motors: one is a rotary motor which converts the electric energy to a rotational movement, and the other is a reciprocating motor which converts the electric energy to a linear reciprocal movement.
As a driving source, the motor is adopted for use to various fields. Especially, it is installed in almost every home appliance such as a refrigerator, an air conditioner, a washing machine or an electric fan. In case of the refrigerator and the air conditioner, the motor is not only used to rotate a ventilating fan, but also installed as a driving source at a compressor of a cooling cycle apparatus of the refrigerator and the air conditioner.
FIG. 1
is a drawing illustrating an example of a reciprocating motor in accordance with a conventional art.
As shown in
FIG. 1
, the reciprocating motor includes a cylindrical outer core
10
formed having a predetermined width and length, a cylindrical inner core
20
inserted in the outer core
10
with a predetermined space, a winding coil
30
coupled to the outer core
10
or the inner core
20
, and a mover
40
movably inserted between the outer core
10
and the inner core
20
.
FIG. 1
shows the structure that, the winding coil
30
is coupled to the outer core
10
.
The outer core
10
has a ‘U’-shaped section with a predetermined thickness, so that an opening
11
is formed in which the winding coil
30
is positioned. The ‘U’-shaped outer core
10
forms a pass part
12
at which a flux flows, and a pole part
13
is formed at both ends of the pass part
12
.
The inner core
20
has a section with a length corresponding to that of the outer core
10
and a predetermined width.
The outer core
10
and the inner core
20
are fixed at a separate frame (not shown) to constitute a stator (S).
The mover
40
includes a cylindrical magnet holder
41
inserted between the outer core
10
and the inner core
20
and a plurality of permanent magnets
42
combined at the outer circumferential surface of the magnet holder
41
.
The operation of the reciprocating motor constructed as described above will now be explained.
FIG. 2
is a sectional view showing an operational state of the general reciprocating motor.
As shown in
FIG. 2
, first, when a current flows to the winding coil
30
, a flux is formed around the winding coil
30
due to the current flowing along the winding coil
30
. The flux flows to form a closed loop along the pass part
12
of the outer core and the inner core
20
which constitute the stator (S).
The interaction between the flux according to the current flowing along the coil
30
and the flux according to the permanent magnet
42
constituting the mover
40
makes the permanent magnet
42
to move in the axial direction.
When the direction of the current flowing to the winding coil
30
is changed, the direction of the flux formed at the pass part
12
of the outer core and the inner core
20
is accordingly changed, and thus, the permanent magnet
42
is moved in the opposite direction.
When the current is supplied to the permanent magnet
42
by changing its direction by turns, the permanent magnet
42
is moved linearly and reciprocally between the outer core
10
and the inner core
20
. Accordingly, the mover
40
has a linear reciprocal driving force.
In the reciprocating motor, the length Lm of the permanent magnet
42
of the mover
40
is usually equivalent to the sum of the length Lp of the pole part and the interpole distance Lb.
Accordingly, since the length of the permanent magnet
42
is in proportion to the interpole distance Lb positioned at both sides of the opening
11
, the shorter the interpole distance Lb is, the shorter Lm of the permanent magnet
42
becomes.
The length Lp of the pole part corresponds to the stroke, and the interpole distance Lb is equivalent to the width of the entrance of the opening
11
.
The permanent magnet
42
of the mover
40
of the reciprocating motor costs much for its materials. Thus, in order to incur a less production cost, its amount to be used should be reduced. Especially, in case of a mass production, it is requisite to reduce a production unit cost.
In addition, in a case that the reciprocating motor is mounted in a different system, in order to occupy a less installation space, the reciprocating motor needs to be compact structurally.
Thus, it is critical to reduce the length of the high-priced permanent magnet
42
by reducing the interpole distance Lb to thereby reduce the cost of materials, prevent leakage of the magnetic flux and have a compact structure while obtaining the inner space of the opening as large as possible where the winding coil
30
is positioned.
In consideration of this, a structure as shown in
FIG. 3
has been proposed.
FIG. 3
is a sectional view of a reciprocating motor proposed during a research and development of the inventor of the present invention.
With reference to
FIG. 3
, the structure includes a ‘U’-shaped pass part
12
, of the outer core
10
where the winding coil
30
is positioned, having a section with a predetermined thickness; a triangular extended part
14
protrusively extended in a triangle form at inner sides of both ends of the pass part
12
, and a pole part
15
formed by the both ends of the pass part
12
and the triangular extended part
14
.
An opening
16
where the winding coil
30
is positioned is formed by the inner side of the pass part
12
and the inner side of the triangular extended part
14
. The distance between the inner ends of the triangular extended parts
14
, that is, the interpole distance Lb′ between the pole parts
15
, forms the entrance of the opening
16
.
However, with such a structure, if the triangular extended part
14
is enlarged to reduce the width of the entrance of the opening
16
in which the winding coil
30
is positioned, the inner space of the opening
16
becomes small, causing that the number of winding of the winding coil is reduced. On the other hand, if the triangular extended part
14
is made small to enlarge the inner space of the opening
16
, the entrance of the opening
16
is widened, causing increase in the amount of the permanent magnet to be used.
Meanwhile, if the triangular extended part
14
is sharpened to maintain the inner space of the opening
16
and shorten the length of the entrance of the opening
16
, that is, if the angle made as the inner face of the pass part
12
and the inner face of the triangular extended part
14
meet is almost perpendicular, the flow resistance of the flux flowing to the outer core
10
is rapidly increased, causing a damage to the flux.
In addition, with such a structure, when the mover
40
including the permanent magnet
42
is being linearly and reciprocally moved, the range in which the end portion of the mover
40
is protruded outwardly of the pole part
15
becomes wide. Thus, the space between the mover and other components should be distanced, causing a problem that its structure is enlarged.
DISCLOSURE OF THE INVENTION
Therefore, an object of the present invention is to provide a reciprocating motor in which the width of an entrance of an opening where a winding coil is positioned, that is, the interpole distance is minimized, the space of the opening is maximized to reduce an amount of a pricy permanent magnet to be used, its output is heightened and its structure is simplified to be compact.
In order to achieve the above objects, there is provided a reciprocating motor having an outer core, inner cores inserted at a predetermined distance from t

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