Pumps – Expansible chamber type – Having additional chamber intake connection from nonpumping...
Reexamination Certificate
2000-01-18
2001-10-09
Freay, Charles C. (Department: 3746)
Pumps
Expansible chamber type
Having additional chamber intake connection from nonpumping...
C137S540000, C417S440000
Reexamination Certificate
active
06299417
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly, to a back pressure structure of an intermediate pressure of a scroll compressor in which an intermediate pressure space between a main frame and a orbiting scroll is maintained in a constant intermediate pressure state to thereby prevent an abnormal movement of the orbiting scroll, so that leakage of a compressed gas is prevented, and a position of a suction hole on a fixed scroll is freely selected to be formed, thereby facilitating its fabrication.
2. Description of the Background Art
In general, there are three types of compressors, that is, a reciprocating type, a scroll type and a centrifugal type (widely called a turbo type). The scroll type compressor sucks and compresses gas and discharges it by using a rotor like the centrifugal type or a sliding vane type.
The scroll compressor is classified by a low pressure type scroll compressor and a high pressure type scroll compressor depending on the fact that a suction gas is charged inside a casing or a discharge gas is charged therein.
The high pressure type scroll compressor uses a back pressure method of an intermediate pressure in which the gas permeated between the orbiting scroll and the main frame out of a high pressure discharge gas is partially orbited toward a suction chamber so that an intermediate pressure is maintained between the orbiting scroll and the main frame.
FIG. 1
is a vertical-sectional view of a horizontal type scroll compressor of a high pressure type scroll compressor in accordance with a conventional art.
As shown in the drawing, the conventional horizontal type scroll compressor is constructed in that a main frame
2
and a sub-frame
3
are respectively fixed at both sides of a horizontal casing
1
filled with oil at a predetermined height, a drive motor
4
having a stator
4
A and a rotor
4
B is mounted between the main frame
2
and the sub-frame
3
, and a driving shaft
5
is press-fitted by passing through the main frame
2
at the center of the rotor
4
B of the drive motor.
A wrap
6
a
is formed in an involute curve on the upper surface of the main frame
2
so that the orbiting scroll
6
combined eccentrically to the driving shaft
5
is rotatably installed. On the upper surface of the orbiting scroll
6
, a fixed scroll
7
, where a wrap
7
a
is formed in an involute curve so as to form a plurality of compressive chambers by being engaged with the wrap
6
a
of the orbiting scroll
6
, is fixedly installed at the main frame
2
.
At one side of a plate at margin of the fixed scroll
7
contacted when the orbiting scroll
7
is orbited, a suction pressure space
7
c
in which a flat plate-type back pressure control valve
8
elastically supported by a coil spring
9
is installed is formed.
A suction hole
7
d
that is opened and closed when the orbiting scroll
8
is orbited is formed at the side close to the compressive chamber of the suction pressure space
7
c
of the fixed scroll
7
.
At the side of the suction pressure space
7
c
toward the compressive chamber, there are formed a vent hole
7
e
for guiding the intermediate pressure gas flown into the suction pressure space
7
c
through the suction hole
7
d
to the outermost compressive chamber among the compressive chambers.
Reference numeral
5
a
denotes a oil passage,
7
f
denotes a leak resistance stopper,
11
denotes a discharge pipe,
10
denotes a suction pipe, and MS denotes an intermediate pressure space.
The operation of the scroll compressor constructed as described above according to the conventional art will now be explained.
When a power is supplied, the rotor
4
B is rotated along with the driving shaft
5
in side the stator
4
A by the power, rendering orbiting scroll
6
eccentrically rotated as long as the eccentric distance, and as the orbiting scroll
6
is orbited at a distance as long as the revolving diameter centering around the driving shaft
5
, a plurality of compressive chambers are formed between the wraps
6
a
and
7
a
of the orbiting scroll
6
and the fixed scroll
7
.
As the orbiting scroll
6
is continuously orbited and moved toward the center, the volume of the compressive chambers is reduced, according to which a coolant gas flown therein through the suction pipe
10
is compressed and discharged to the inside of the casing
1
through the discharge port
7
b
of the fixed scroll
7
in the final compressive chamber.
The discharge gas of high pressure discharged to the inside of the casing
1
flows toward the sub-frame
3
through a coolant passing hole (not shown) formed in the main frame, and thus, the entire casing
1
is highly pressurized, of which a partial gas flows into the intermediate pressure space MS formed between the main frame
2
and the orbiting scroll
6
through a void between the driving shaft
5
and the main frame
2
.
The highly pressurized discharge gas flown into the intermediate pressure space MS thrusts the main frame
2
and the orbiting scroll
6
in the opposite directions to each other, resulting in that the orbiting scroll
6
and the fixed scroll
7
are excessively adhered, which causes an increase of a friction loss.
However, in this respect, in case that the pressure of the intermediate pressure space MS goes beyond a set value of a spring elasticity value determined by a spring elasticity determined by the coil spring
9
, when the orbiting scroll is rotatably moved, the intermediate pressure gas pushes upward the back pressure control valve
8
and flows to the suction pressure space
7
c
through the opened suction hole
7
d.
The intermediate gas flown to the intermediate pressure space
7
c
flows to the first compressive chamber through the vent hole
7
e
to thereby maintain the pressure of the intermediate pressure space MS at an adequate level, thereby preventing an excessive friction loss for the orbiting scroll
6
and the fixed scroll
7
.
Thereafter, when the suction hole
7
d
is closed according as the orbiting scroll
6
is continuously orbited, the back pressure control valve
8
is lowered down by the coil spring
9
, thereby blocking the suction hole
7
d.
However, as to the back pressure structure of the intermediate pressure of the conventional scroll compressor, since the bottom plane of the back pressure control valve
8
is flatly formed so as to be contacted with the plane where the suction hole
7
d
of the suction pressure space
7
c
is formed, the areas pressurized by the discharge gas flown into the suction hole
7
d
are different to each other according to the opening and closing state of the valve
8
.
Thus, a reactivity of the back pressure control valve
8
is delayed, so that the variation of the intermediate pressure is deepened, and thus, the movement of the orbiting scroll
6
becomes unstable, degrading the efficiency of the compressor.
In addition, there is a restriction for the suction hole
7
d
in the aspect that it must be formed within the orbiting radius of the orbiting scroll
6
.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a back pressure structure of a scroll compressor in which a control valve is quickly reacted on an intermediate gas flown into a suction hole when the back pressure control valve is closed or opened, so that the intermediate pressure is constantly formed.
Another object of the present invention is to provide a back pressure structure of a scroll compressor in which a suction hole is freely formed in any place without being restricted by other parts, so that it can be easily made.
To achieve these and other advantages and in accordance with the purposed of the present invention, as embodied and broadly described herein, there is provided a back pressure structure of a scroll compressor having a fixed scroll forming a plurality of compressive chambers together with an orbiting scroll in its casing; including: a suction pressure space having a predetermined volume formed at one side of the fixed scroll; a sucti
Chang Young Il
Shin Dong Ku
Fleshner & Kim LLP
Freay Charles C.
Gray Michael K.
LG Electronics Inc.
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