Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2002-05-31
2004-08-31
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C092S13000R, C092S13000R
Reexamination Certificate
active
06783335
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 2001-74200 filed Nov. 27, 2001, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to linear compressors for refrigerating systems and air conditioning systems, such as refrigerators and air conditioners, and, more particularly, to a linear compressor provided with an anti-collision device preventing a movement of a piston, which exceeds an upper dead center position of a piston inside a cylinder.
2. Description of the Prior Art
As is well known to those skilled in the art, a compressor is a machine that sucks and compresses the gas refrigerant in a refrigerating system or an air conditioning system, such as a refrigerator or an air conditioner, operated by performing a refrigeration cycle. Compressors have been typically classified into two types: reciprocating compressors and rotary compressors. The reciprocating compressors compress the gas refrigerant by a rectilinear reciprocation of a piston, while the rotary compressors compress the gas refrigerant by rotation of one or more vanes. A linear compressor is a type of reciprocating compressor, and linearly reciprocates a piston using a linear motor to compress the gas refrigerant Such a linear compressor has low energy loss, thus being high in energy efficiency in comparison with the other type of compressors.
FIGS. 1 and 2
are side sectional views, showing the construction of a conventional linear compressor.
FIG. 1
shows the linear compressor when a piston is positioned at a stop position, and
FIG. 2
shows the compressor when the piston is positioned at an upper dead center position.
As shown in
FIGS. 1 and 2
, the conventional linear compressor comprises a drive unit
10
and a compressing unit
20
, which are housed in a hermetic casing
1
. The drive unit
10
generates drive power when electricity is applied from an external power source, while the compressing unit
20
sucks the gas refrigerant and compresses the gas refrigerant using the drive power transmitted from the drive unit
10
.
The compressing unit
20
comprises a hollow cylinder
21
defining a compressing chamber
22
in a cylindrical bore with a cylinder head
23
assembled including an end of the hollow cylinder
21
which guides the suction and the discharge of the gas refrigerant. A piston
24
is movably received in the compressing chamber
22
of the hollow cylinder
21
, and linearly reciprocates in the compressing chamber
22
using the drive power transmitted from the drive unit
10
.
The drive unit
10
, which is a type of linear motor, comprises a cylindrical white iron assembly
11
arranged around the hollow cylinder
21
. A core
12
, wound with a coil
13
, is arranged such that the core
12
and coil
13
surround the iron assembly
11
with an annular gap defined between the iron assembly
11
and the core
12
. When an alternating current AC is applied to the coil
13
of the core
12
, the core
12
generates a magnetic flux. A magnet
14
is positioned in the gap formed between the iron assembly
11
and the core
12
such that the magnet
14
reciprocates along with the piston
24
.
The core
12
is fabricated by closely layering a plurality of steel sheets, and is supported by both the hollow cylinder
21
and a support frame
21
a
. The magnet
14
is mounted to a movable member
25
integrated with the piston
24
into a single structure, and linearly reciprocates in cooperation with the magnetic flux generated by the core
12
. Due to the linear reciprocating action of the magnet
14
, the piston
24
reciprocates in the hollow cylinder
21
.
Both the drive unit
10
and the compressing unit
20
are elastically suspended in the hermetic casing
1
by a plurality of coil springs
2
elastically supporting the hollow cylinder
21
at a lower portion inside the hermetic casing
1
. A plurality of spacers
4
vertically extends upward from an upper surface of the support frame
21
a
of the hollow cylinder
21
to the same height. A resonant spring
3
, which is a type of plate spring, is mounted to ends of the spacers
4
. The movable member
25
, which is integrated with the piston
24
into the single structure and reciprocates by the drive unit
10
, is mounted at an end to the center of the resonant spring
3
. The piston
24
linearly reciprocates in the hollow cylinder
21
by both the resonant spring
3
and the movable member
25
, thus sucking the gas refrigerant into the hermetic casing
1
and compressing the refrigerant prior to discharging the compressed gas refrigerant from the hermetic casing
1
.
The cylinder head
23
has a suction chamber
6
and an exhaust chamber
8
. The suction chamber
6
, which is provided with a suction valve
5
, guides the gas refrigerant from the outside of the hermetic casing
1
into the compressing chamber
22
. The exhaust chamber
8
, which is provided with an exhaust valve
7
, guides the compressed gas refrigerant from the compressing chamber
22
to the outside of the hermetic casing
1
.
When an alternating current AC is applied to the coil
13
of the drive unit
10
, the coil
13
generates a magnetic flux. This magnetic flux of the coil
13
cooperates with the magnetic field of the magnet
14
, which is mounted to the movable member
25
, thus allowing the movable member
25
to reciprocate in a vertical direction while vibrating the resonant spring
3
. The piston
24
thus linearly reciprocates in the cylinder
21
. When the piston
24
moves from a stop position of
FIG. 1
to a lower dead center position during a reciprocating action, the suction valve
5
is opened to suck the gas refrigerant from the suction chamber
6
into the compressing chamber
22
. When the piston
24
moves to a upper dead center position as shown in
FIG. 2
, the suction valve
5
is closed and the exhaust valve
7
is opened to discharge the compressed gas refrigerant from the compressing chamber
22
to the exhaust chamber
8
.
The natural frequency of the resonant spring
3
according to the mass of the piston
24
, magnet
14
and movable member
25
is set to be almost equal to the frequency of the alternating current AC applied to the coil
13
of the core
12
, and the drive unit
10
can generate high drive power caused by resonance. The amplitude of both the reciprocating piston
24
and the movable member
25
is regulated by controlling the applied voltage. In such a case, to allow the piston
24
to stably reciprocate with a predetermined amplitude, a separate control unit (not shown) capable of stably controlling the amplitude of the piston
24
can be provided.
In such a conventional linear compressor, the volumetric efficiency of the compressor varies in accordance with a gap volume determined by a minimum gap distance Xc between the cylinder head
23
and the upper dead center position of the piston
24
. That is, higher volumetric efficiency of the linear compressor can be obtained as the minimum gap distance Xc is reduced. Therefore, when high volumetric efficiency of the compressor is desired, reducing the gap volume as much as possible by controlling the amplitude of the piston
24
such that the piston
24
can approach close to the cylinder head
23
and the suction valve
5
during an operation of the compressor is preferable.
However, during a reciprocating action of the piston in the cylinder of the conventional linear compressor, the behavior of the piston may become unstable, thereby abruptly and rapidly increasing the amplitude of the piston due to unexpected internal or external causes, such as unexpected rapid variation in the applied voltage or unexpected rapid variation in the pressure of the refrigeration cycle. When the amplitude of the piston rapidly increases as described above, the end of the piston may come into collision with the suction valve and/or the cylinder head, thus generating operational noise, in addition
Freay Charles G.
Staas & Halsey , LLP
LandOfFree
Linear compressor having an anti-collision device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Linear compressor having an anti-collision device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear compressor having an anti-collision device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3342074