Pumps – With condition responsive pumped fluid control – Pump inlet or pump chamber vented to ambient
Reexamination Certificate
2003-01-09
2004-08-03
Yu, Justine R. (Department: 3746)
Pumps
With condition responsive pumped fluid control
Pump inlet or pump chamber vented to ambient
C418S055100, C417S310000
Reexamination Certificate
active
06769881
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly, to a vacuum preventing device for a scroll compressor in which gas in a discharge region flows backward to a suction region at the time of an abnormal driving such as a pump down or an expansion valve blocking, thereby preventing a vacuum of the compressor.
2. Description of the Background Art
Generally, a compressor is a device for converting mechanical energy into latent energy of a compression fluid, and is largely classified into a reciprocation compressor, a scroll compressor, a centrifugal compressor, and a vane compressor by compression methods.
The scroll compressor has a structure that gas is sucked, compressed, and discharged by using a rotation member like the centrifugal type and the vane type differently from the reciprocating type which uses a linear reciprocation of an piston.
FIG. 1
is a longitudinal sectional view showing an inner part of the conventional scroll compressor.
As shown, the scroll compressor comprises: a case
1
divided into a gas suction pipe SP and a gas discharge pipe DP; a main frame
2
and a sub frame (not shown) respectively installed at both sides of upper and lower portions of an inner circumference surface of the case
1
; a driving motor
3
installed between the main frame
2
and the sub frame; a rotation shaft
4
engaged to a center portion of the driving motor
3
for transmitting a rotation force of the driving motor
3
; an orbiting scroll
5
installed to have an eccentric rotation at an upper portion of the rotation shaft
4
and having a wrap
5
a
of an involute curve shape at the upper portion thereof; and a fixed scroll
6
engaged to the orbiting scroll
5
, and having a wrap
6
a
of an involute curve shape so as to form a plurality of compression spaces P therein.
The case
1
is divided into a suction region S
1
and a discharge region S
2
by a high and low pressure separation plate
7
, and a compression region S
3
is formed at a position connected to the compression space P.
A gas inlet
6
b
and an outlet
6
c
are respectively formed at a lateral surface and a center portion of the fixed scroll
6
, and a non-return valve
8
for preventing discharged gas from flowing backward is installed at an upper surface of the fixed scroll
6
.
The main frame
2
and the sub frame are fixed to the inner circumference surface of the case
1
by a fixation means such as welding, and the fixed scroll
6
is also fixed to a bottom surface of the high and low pressure separation plate
7
by a fixation means such as a bolt.
Meantime, in case of a pump down and an expansion valve blocking, the suction region S
1
of the compressor becomes a high vacuum state. At this time, components relevant to the compressor may be damaged and destroyed.
To prevent this, a vacuum preventing device
20
is provided in the conventional art.
FIG. 2
is a longitudinal sectional view showing an operation at the time of a normal driving in the vacuum preventing device of
FIG. 1
,
FIG. 3
is a longitudinal sectional view showing an operation at the time of an abnormal driving in the vacuum preventing device of
FIG. 1
, and
FIG. 4
is a sectional view taken along line A—A of FIG.
2
.
Referring to
FIGS. 2 and 3
, the vacuum preventing device
20
includes a chamber
10
formed at one side of the fixed scroll
6
, and a discharge hole
11
connected to the discharge region S
2
at an upper surface of the chamber
10
.
A compression hole
12
connected to the compression region S
3
is formed at a bottom surface of the chamber
10
, a plug
14
having a suction hole
13
is fixed to an opening portion of the chamber
10
by a fixation pin
15
, and the suction hole
13
is connected to the discharge hole
11
.
An open/close member
17
for selectively connecting the discharge hole
11
and the suction hole
13
is movably installed in the chamber
10
.
A spring
16
for limiting a movement of the open/close member
17
and providing an elasticity force thereto is installed at the opening portion of the chamber
10
.
Hereinafter, operations of the conventional scroll compressor will be explained.
First, when a power source is applied to the driving motor
3
, the driving motor
3
rotates the rotation shaft
4
, and the orbiting scroll
5
engaged to the rotation shaft
4
is rotated to an extent of its eccentric distance.
At this time, a plurality of compression spaces P formed between the wrap
5
a
of the orbiting scroll
5
and the wrap
6
a
of the fixed scroll
6
gradually move towards a center portion of the fixed scroll
6
as the orbiting scroll
5
continuously performs an orbiting movement, thereby having a decreased volume.
By the decreased volume of the compression spaces P, gas of the suction region S
1
is sucked into the compression space P through the inlet
6
b
, and the sucked gas is discharged to the discharge region S
2
through the outlet
6
c.
When the compressor is normally driven, a pressure of the compression region is larger than an elasticity force of the spring
16
, so that the open/close member
17
overcomes the elasticity force of the spring
16
and closes the discharge hole
11
.
However, the compressor is abnormally driven, a pressure of the compression region is smaller than the elasticity force of the spring
16
, so that the open/close member
17
is shoved by the elasticity force of the spring
16
and opens the discharge hole
11
. At this time, the discharge hole
11
is connected to the suction hole
13
.
As the discharge hole
11
and the suction hole
13
are connected to each other, gas of the discharge region S
2
flows backward into the suction region S
1
through the discharge hole
11
and the suction hole
13
, thereby releasing a vacuum of the compressor.
As shown in
FIG. 4
, in the conventional scroll compressor, a minute clearance t is formed between an inner wall of the chamber
10
and an outer circumference surface of the open/close member
17
so as to induce a smooth slide movement of the open/close member
17
.
Generally, the clearance is fabricated as the minimum size so that the open/close member
17
can slide the chamber
10
, and fabricated as a minute size enough not to leak gas through the discharge hole
11
when the open/close member
17
closes the discharge hole
11
.
When the clearance t becomes smaller, gas is closed more efficiently but an operation of the open/close member
17
is not smooth. On the contrary, when the clearance t becomes larger, gas leakage is increased and an operation of the open/close member
17
is smooth. Accordingly, considering the operation of the open/close member
17
, the clearance t is designed and fabricated within a tolerance limit range.
However, in the conventional art, when the compressor is normally driven, the open/close member
17
receives a pressure downwardly by a gas pressure of the discharge region S
2
. At this time, a bottom surface of the open/close member
17
is adhered to an inner bottom surface of the chamber
10
and an upper surface of the open/close member
17
is more separated from an inner upper surface of the chamber
10
. That is, the clearance t becomes large more than the tolerance limit range.
When the clearance t becomes large, a part of gas of the discharge region leaks to the suction region through the clearance, thereby degrading a compression efficiency of the compressor.
Also, in the conventional art, since high minuteness is required at the time of designing and fabricating the clearance, a high cost is required and a productivity is degraded.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a vacuum preventing device for a scroll compressor, in which a rotation member which selectively connects a discharge hole to a suction hole by being rotated by a pressure difference between the compression region and the discharge region is installed, so that a vacuum of the compressor can be efficiently prevented at the time of an abnormal driving and
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Liu Han L
Yu Justine R.
LandOfFree
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