Rotary compressor

Details Rotary compressor Rotary compressor

2000-07-27

2002-01-08

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

With relatively movable partition member

C418S064000, C418S065000, C418S066000, C418S067000, C418S180000

Reexamination Certificate

active

06336800

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to rotary compressors and, more particularly, to a rotary compressor of the low operational noise type, having a bypass passage on the internal surface of its cylinder at a position around a fluid exhaust stroke initiating point to effectively reduce excessive pressure pulsation generated at the initial stage of an exhaust stroke, thus effectively reducing impact exciting force caused by the pressure pulsation within the compression chamber of the cylinder and effectively reducing pulsation noise having a wide frequency band.
2. Description of the Prior Art
As well known to those skilled in the art, compressors are machines used for compressing fluid, such as liquid or gas, to a desired pressure and have been preferably and widely used for a variety of applications. Such compressors are recognized as very important elements in a variety of refrigeration systems, such as air conditioners or refrigerators, since the compressors are used for compressing refrigerant of refrigeration cycles and determine the operational capacities and operational efficiencies of such refrigeration systems. Conventional compressors have been classified into two types: rotary compressors and scroll compressors. Of the two types, the scroll compressors are designed to compress refrigerant by a rotating action of a rotatable scroll, operated in conjunction with a drive unit, relative to a fixed scroll. On the other hand, the rotary compressors compress refrigerant by a roller, which is operated in conjunction with a drive unit and is eccentrically rotated within the bore of a cylinder.
FIGS. 1 and 2
show the construction of a conventional rotary compressor. As shown in the drawings, the conventional rotary compressor comprises a casing
10
provided with both a refrigerant inlet port
10
a
for introducing refrigerant into the casing
10
and a refrigerant outlet port
10
b
for discharging compressed refrigerant from the casing
10
. A stator
11
is fixed within the casing
10
, while a rotor
12
is positioned to be electromagnetically rotatable relative to the stator
11
when it is electrically activated. A rotating shaft
13
having an eccentric portion (
13
′) is integrated with the central axis of the rotor
12
and is rotatable along with the rotor
12
. A roller
17
is fixed to the eccentric portion (
13
′) of the rotating shaft
13
and set within the bore
16
a
of a cylinder
16
. The cylinder
16
has a suction port
21
and an exhaust port
22
and compresses working fluid, sucked into the bore
16
a
through the suction port
21
, in accordance with an eccentric rotating action of the roller
17
within the bore
16
a
and discharges the compressed fluid from the bore
16
a
through the exhaust port
22
.
A vane
18
is provided within the bore
16
a
of the cylinder
16
at a position around the exhaust port
22
and is normally biased by a spring
19
so as to elastically come into contact with the external surface of the roller
17
. The above vane
18
partitions the chamber, formed between the cylinder
16
and the roller
17
, into a variable suction chamber
16
b
and a variable compression chamber
16
c
. An exhaust control valve (not shown) is provided within the exhaust port
22
of the cylinder
16
and is used for controlling the port
22
so as to allow the port
22
to exhaust the compressed fluid from the cylinder
16
when the roller
17
completely rotates within the cylinder
16
at a predetermined angle. A main bearing
14
is installed at an upper position within the cylinder
16
, while a sub-bearing
15
is installed at a lower position within the cylinder
16
.
The above conventional rotary compressor is operated as follows: That is, when the compressor is electrically activated, the rotor
12
is electromagnetically rotated along with the rotating shaft
13
relative to the stator
11
. Therefore, the roller
17
is eccentrically rotated within the cylinder bore
16
a
while coming into tangential contact with the internal surface of the cylinder
16
. When the roller
17
is eccentrically rotated within the cylinder bore
16
a
, refrigerant is introduced into the bore
16
a
through the suction port
21
. The refrigerant is thus gradually compressed as the compression chamber
16
c
, formed by the roller
17
, the internal surface of the cylinder
16
and the vane
18
, is gradually reduced in its volume due to the eccentric rotating action of the roller
17
within the cylinder bore
16
a
. When the pressure of the refrigerant reaches a predetermined reference level as it is compressed, the exhaust control valve is opened, thus allowing the compressed refrigerant to be exhausted from the cylinder
16
through the exhaust port
22
. The exhausted compressed air is, thereafter, discharged from the compressor through the refrigerant outlet port
10
b
formed on the casing
10
of the compressor.
In the drawings, the reference numeral
20
denotes an accumulator.
FIG. 3
is a sectional view corresponding to
FIG. 2
, showing a resonator installed within the cylinder of the conventional rotary compressor. As shown in the drawing, a resonator
40
, designed to reduce operational noise of a predetermined frequency band, is formed in the cylinder
16
to communicate with the exhaust port
22
. Due to the resonator
40
, the compressor reduces pulsation noise, caused by refrigerant gas within the cylinder
16
during a refrigerant compression stroke of the cylinder
16
. The resonator
40
also prevents an undesirable quick discharging of the pressure pulsation from the cylinder
16
during a refrigerant exhaust stroke of the cylinder
16
, thus reducing operational noise and vibration during the refrigerant exhaust stroke. The resonator
40
is determined in its resonating frequency band in accordance with both the shape of a resonating cavity determined by the acoustic resonance and the shape of a pressure leading passage.
Since both the shape of the resonating cavity and the shape of the pressure leading passage are fixed, the resonating frequency band of the resonator
40
for the cylinder
16
is fixed. However, since the compression chamber
16
c
is gradually reduced in its volume in a refrigerant compression stroke, the internal pressure of the compression chamber
16
c
continuously varies, with the pressure pulsation being exhausted from the cylinder
16
through the exhaust port
22
. Therefore, the compressor inevitably generates operational noises having a variety of frequency bands, and so the resonator
40
, having a fixed resonating frequency band, does not desirably reduce the pressure pulsation in the compressor.
In addition, lubrication oil may be undesirably introduced from the cylinder bore
16
a
into the resonating cavity of the resonator
40
at the initial stage of the operation of the compressor. In such a case, it is almost impossible to effectively remove the lubrication oil from the resonator
40
during the operation of the compressor since the pressure leading passage of the resonator
40
is positioned above the resonating cavity. The amount of lubrication oil, remaining in the resonating cavity, varies during the operation of the compressor, and changes the noise reduction characteristics of the resonator
40
. Therefore, the resonator
40
does not maintain its designed noise reductirefrigeranton characteristics and fails to accomplish its desired noise reducing operational effect.
In addition, since the resonator
40
is formed on the middle portion of the exhaust line while communicating with the exhaust port
22
, the quantity of refrigerant, which is undesirably remained in the compression chamber
16
c
at the final stage of a compressed refrigerant exhaust stroke and is free from exhausting compressed refrigerant from the cylinder
16
, is undesirably increased. Therefore, the highly compressed refrigerant gas, remaining in the dead cavity, is undesirably fed back to the suction chamber
16
b
of the cylinder bore
16
a
after the ex

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