U.S. patent application number 13/572410 was filed with the patent office on 2012-12-06 for mechanism to raise the efficiency of a reciprocating refrigeration compressor.
Invention is credited to Xiaohua YUAN.
Application Number | 20120308419 13/572410 |
Document ID | / |
Family ID | 42512611 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120308419 |
Kind Code |
A1 |
YUAN; Xiaohua |
December 6, 2012 |
Mechanism to Raise the Efficiency of a Reciprocating Refrigeration
Compressor
Abstract
An improvement to raise the efficiency of a reciprocating
refrigeration compressor, the improvement comprising a channel in
the piston that transfers pressure from the clearance volume of the
cylinder to the low pressure side of the piston when an opening of
the channel aligns with a groove or a duct in the cylinder wall.
The channel comprises a ball extending from and held to the
clearance volume opening of the channel by a spring. When the
spring is compressed, the ball is moved from the opening, and
pressure in the clearance volume is transferred to the low pressure
side of the piston.
Inventors: |
YUAN; Xiaohua; (US) |
Family ID: |
42512611 |
Appl. No.: |
13/572410 |
Filed: |
August 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12703506 |
Feb 10, 2010 |
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13572410 |
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12727907 |
Mar 19, 2010 |
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12703506 |
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Current U.S.
Class: |
417/490 |
Current CPC
Class: |
F04B 53/14 20130101;
F04B 53/148 20130101; F04B 53/12 20130101 |
Class at
Publication: |
417/490 |
International
Class: |
F04B 7/04 20060101
F04B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 2010 |
CN |
2010101014022 |
Claims
1. An improved reciprocating compressor comprising a cylinder body
and a piston, the improvement comprising at least one channel in
the piston, the channel connecting a clearance volume at a first
side of the piston to a low pressure side of the piston, wherein
the channel comprises: a) a first segment on the clearance volume
side of the piston comprising: a spherical-shaped opening having a
diameter smaller than a diameter of the remainder of the segment,
and a ball, a spring, and an adjustable set screw, the ball i)
moveable in the first segment and in communication with the spring,
ii) extending into the spherical-shaped opening, and iii) having a
diameter greater that the opening diameter and less than the
diameter of the remainder of the segment, and b) a second segment
having an opening at the low pressure side of the piston, the
second segment having a diameter smaller than the diameter of the
first segment, wherein the ball seals the channel when the spring
is extended and opens the channel when the spring is
compressed.
2. The improved compressor of claim 1 wherein the set screw is in
communication with the spring such that adjusting the set screw
applies a force from the spring to the ball, forcing the ball to
seal the spherical-shaped opening.
3. A method of improving the efficiency of a reciprocating
compressor comprising using the improved compressor of claim 1
wherein, when the piston completes a compression stroke, a portion
of the ball extending from the spherical-shaped opening contacts a
valve plate located in the clearance volume side of the piston, the
contact moving the ball in the channel by compressing the spring to
open the spherical-shaped opening to allow high pressure in the
clearance volume to flow through the channel to the low pressure
side of the piston.
4. The method of claim 3 wherein the high pressure flows to a
compressor crankcase.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of and claims
priority to Chinese Patent Application No. 2010101014022 filed Jan.
27, 2010, U.S. patent application Ser. No. 12703506 filed Feb. 10,
2010, U.S. patent application Ser. No. 12727907 filed Mar. 19,
2010, and Provisional Application No. 61314372 filed Mar. 16, 2010,
each of which is hereby incorporated by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to reciprocating
refrigeration compressors and specifically to improving efficiency
by improving the structure of the valve plate, piston, and cylinder
bore.
BACKGROUND OF THE INVENTION
[0003] A reciprocating refrigeration compressor is composed of main
parts, including the body, crankshaft, cylinder cover, valve plate,
piston, connecting rod, motor, motor cover, bearing housing, bottom
plate, and the like. Typically, an electric motor drives the
crankshaft, which is connected to a connecting rod and piston. The
crankshaft moves the piston upward and downward. A valve plate on
the cylinder plane has a suction port and a discharge port. As the
piston moves downward on the suction stroke, pressure is reduced in
the cylinder. Refrigeration systems use a circulating liquid
refrigerant that enters the compressor as a vapor. When the
pressure falls below that in the compressor suction line, the
pressure differential causes the suction valves to open and forces
the refrigerant vapor to flow into the cylinder.
[0004] As the piston reaches the bottom of its stroke and starts
upward on the compression stroke, pressure is developed in the
cylinder, forcing the suction valves closed. The pressure in the
cylinder continues to rise as the piston moves upward, compressing
the vapor trapped in the cylinder. When the pressure in the
cylinder exceeds the pressure existing in the compressor discharge
line, the discharge valve is forced open, and the compressed gas
flows into the discharge line which is connected to the
condenser.
[0005] When the piston starts downward, the reduction in pressure
allows the discharge valve to close because of the higher pressure
in the condenser and discharge line, and the cycle is repeated.
[0006] Three main factors affect compressor efficiency: 1) The
seating of the valves; 2) the temperature of the cylinder walls (if
the cylinder wall are hot and suction gas entering the cylinder on
the intake stroke is heated by the cylinder walls, the gas expands,
resulting in a reduced weight of gas entering the compressor); and
3) the clearance volume of the cylinder.
[0007] The most important factor affecting compressor efficiency is
clearance volume. The clearance volume is composed of following
five areas: 1) clearance above the piston; 2) clearance for reed
thickness; 3) discharge ports on valve plate; 4) clearance between
the piston and the cylinder wall; and 5) clearance for the reed
opening and stopping.
[0008] When the piston starts down on the suction stroke, the
residual high pressure gas in the clearance volume expands and its
pressure is reduced. No vapor from the suction line can enter the
cylinder until the pressure in the cylinder has been reduced below
the suction line pressure. Thus, the first part of the suction
stroke is actually lost from a capacity standpoint, and as the
compression ratio increases, a greater percentage of the suction
stroke is occupied by the residual gas.
[0009] A problem exists in the efficiency of the compressor.
Compressor efficiency is typically effected by the clearance
volume, rate of heat transfer, valve and piston leakage, vapor load
and the like. For example, in a typical three-cylinder compressor
having pistons with a diameter of 65 mm, a high temperature results
in a compression ratio from 4-8; a media temperature application in
a compression ratio from 7-12, and low temperature application
results in a compression ratio from 8-18. Because of the difference
between discharge pressure vs. suction pressure, the efficiency
effects are 12-19%, 16-28%, 19-41%, respectively. The larger the
compression ratio, the more serious the efficiency effect will
be.
[0010] Regular improvements from many compressor builders are: 1)
Mill the reed shape to certain depth (usually is same as reed
thickness) on the top of piston; 2) Reduce the thickness of valve
plate; and 3) Use a model called discs compressor, which has
different valve plate designing to eliminate discharge port
clearance volume. All these methods will reduce the clearance
volume, thus raising the compressor efficiency to certain level,
but the clearance volume issues with high temperature and high
pressure still exists. A further difficulty with existing methods
is that they require major changes to the design of the compressor.
There is a long-standing need for an improvement to compressor
efficiency that is simple and does not require major design
changes.
BRIEF DESCRIPTION OF THE INVENTION
[0011] The present invention is a device and method of improving
the efficiency of a reciprocating refrigeration compressor
comprising a cylinder body and a piston. The method comprises
creating at least one channel in the piston, such that, when a
compression stroke is completed the channel transfers a pressure in
a clearance volume to a low pressure side of the piston.
[0012] In an embodiment, at least one groove is created in a wall
of the cylinder body. In addition, each channel has a first end
comprising an opening on the exterior diameter of the piston
between a pressure ring and an oil ring and a second opening on the
low pressure side of the piston. When a compression stroke is
completed, each opening of the channel on the exterior diameter of
the piston aligns with each groove to transfer a pressure in the
clearance volume to the low pressure side of the piston.
[0013] In an embodiment, a duct is created in the cylinder body.
The duct extends from an opening at the clearance volume side of
the cylinder body to a second opening in the wall of the cylinder.
When a compression stroke is completed, each channel aligns with
each duct and pressure in the clearance volume is transferred to
the low pressure side of the piston through the ducts and the
channels.
[0014] In an embodiment, each channel comprises a first end
comprising a first opening on the clearance volume side of the
piston and a second opening on the low pressure side of the piston.
The first end opening has a diameter smaller than a second diameter
of the remainder of the channel. Each first end comprises a ball, a
spring, and a set screw. The ball has a diameter greater that the
first end diameter and less than the second diameter. The ball is
held against the opening, which is spherical shaped, by the spring,
to seal the first end opening. A portion of the ball extends from
the top of the piston into the clearance volume. When the piston
moves up and down normally, high pressure does not cause
compression of the spring, so that the opening remains sealed by
the ball. When the piston completes a compression stroke, the
portion of the ball extending from the opening contacts the valve
plate. The upward movement of the piston pushes the ball into the
valve plate. Contact with the valve plate compresses the spring and
moves the ball down into the first end opening, thus opening the
channel. High pressure in the clearance volume flows through the
channel to the low pressure side of the piston. As the piston
continues its cycle and moves downward from the valve plate, the
ball is resealed in the opening by energy released from the
spring.
[0015] The present invention is an improvement for a reciprocating
refrigeration compressor, comprising a cylinder body and a piston.
The improvement comprises at least one channel in the piston
connecting the clearance volume to a low pressure side of the
piston.
[0016] In an embodiment, the improvement comprises at least one
groove in a wall of the cylinder body. In addition, each channel
comprises a first end having an opening on a exterior diameter of
the piston between the pressure ring and the oil ring and a second
opening on the low pressure side of the piston. When a compression
stroke is completed, each channel aligns with each groove to
transfer pressure in the clearance volume to the low pressure side
of the piston.
[0017] In an embodiment, the improvement comprises at least one
duct in the cylinder body. The duct has an opening extending from
the clearance volume to a second opening at a point in a wall of
the cylinder. In addition, each channel comprises a first end
having an opening on a exterior diameter of the piston between the
pressure ring and an oil ring. When a compression stroke is
completed, each channel aligns with each duct and pressure in the
clearance volume is transferred to the low pressure side of the
piston through the ducts and the channels.
[0018] In an embodiment, the improvement comprises a channel
comprising a first end having a first opening on the clearance
volume side of the piston and a second opening on the low pressure
side of the piston. The first end opening has a diameter smaller
than a second diameter of the remainder of the channel. Each first
end comprises a ball, a spring, and a set screw. The ball extends
from the first end opening and has a diameter greater that the
first end diameter, but less than the second diameter. The ball is
held against the opening by the spring with a portion of the ball
extending from the top of the piston into the clearance volume to
seal the first end opening of the channel. The ball and spring work
together to open the channel when the ball is pressed and the
spring is compressed, and to close the channel when the spring is
extended.
[0019] The present invention addressed the issue of high pressure
in clearance volume affecting the efficiency of a refrigeration
compressor with a new technical method that releases the high
pressure simply and in very short time. The present invention
provides a substantial improvement in the volumetric efficiency of
the compressor by releasing the high pressure from clearance volume
of the compressor. Among the advantages of this invention are:
[0020] 1) Without the high pressure in the clearance volume, the
efficiency effect from that will be controlled to about 2% only,
thus, the compressor efficiency will be raised dramatically.
[0021] 2) Without the high pressure, high temperature will be
reduced automatically. Without high temperature, the density of
vapor will not have extra expansion. Thus, the extra compressor
efficiency will be raised.
[0022] 3) The high pressure will be released to compressor
crankcase, which will raise internal pressure. Thus the suction
pressure will be raised, and this result will be really helpful to
compressor system capacity.
[0023] 4) High pressure is the main reason for noise. Without high
pressure, the compressor will be quieter.
[0024] 5) Reducing the possibility of "slugging." Slugging occurs
when the compressor vapor condenses to a liquid upon entering the
compressor. Because liquid does not compress, slugging leads to
failure of the compressor.
[0025] As used herein, "approximately" means within plus or minus
25% of the term it qualifies. The term "about" means between 1/2
and 2 times the term it qualifies. The term "substantially" means
that ninety-five percent of the values of the physical property
when measured along an axis of, or within a plane of or within a
volume of the structure, as the case may be, will be within plus or
minus 10% of a mean value.
[0026] As used herein, "implementation" is interchangeable with
"embodiment."
[0027] As used herein, "top" and "up" mean furthest away from the
crankcase, while "bottom" and "down" mean closest to the
crankcase.
[0028] Numerical ranges as used herein are intended to include
every number and subset of numbers contained within that range,
whether specifically disclosed or not. Further, these numerical
ranges should be construed as providing support for a claim
directed to any number or subset of numbers in that range.
[0029] The methods of the present invention can comprise, consist
of or consist essentially of the essential elements and limitations
of the invention described herein, as well as any additional or
optional components, or limitations described herein or otherwise
useful in compositions and methods of the general type as described
herein.
[0030] All references to singular characteristics or limitations of
the present invention shall include the corresponding plural
characteristic or limitation, and vice versa, unless otherwise
specified or clearly implied to the contrary by the context in
which the reference is made. Definitions used herein are intended
to supplement and illustrate, not preclude, the definitions known
to those of skill in the art.
[0031] All combinations of method or process steps as used herein
can be performed in any order, unless otherwise specified or
clearly implied to the contrary by the context in which the
referenced combination is made.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a cross-sectional view of reciprocating
motor-compressor when almost finishing the compression stroke.
[0033] FIG. 2 is a the top view without valve plate mounting.
[0034] FIG. 3 shows the piston moving upward and downward.
[0035] FIG. 4 is a partial enlarged view of an embodiment.
[0036] FIG. 5 is a sectional view.
[0037] FIG. 6 is a partial enlarged depiction of an embodiment.
[0038] FIG. 7 is a cross-sectional view of an embodiment.
[0039] FIG. 8 is a partial enlarged view of an embodiment,
[0040] FIG. 9 is a cross section of an embodiment showing the
piston at an almost completed compression stroke.
[0041] FIG. 10 is an enlarged view of FIG. 8.
[0042] FIG. 11 is an enlarged view of FIG. 10.
DETAILED DESCRIPTION OF THE INVENTION
[0043] The invention is a mechanism of raising the efficiency of
the refrigeration compressor. This mechanism includes cylinder
body, a piston attached to a crankcase, suction valve, discharge
valve, and valve plate, as well as modifications to existing
compressors. The specialty for this mechanism is that there is a
channel to connect the high pressure side of the clearance volume
above the piston to the low pressure side below the piston through
channels within the piston only or on the piston and cylinder body
together. The invention substantially releases the high pressure in
the clearance volume at the end of compression stroke. Reduction of
pressure in the clearance volume increases the efficiency of the
compressor as long as other factors effecting efficiency remain
constant.
[0044] The invention has several methods of connecting the high
pressure side and low pressure side with a channel. First, a
channel is bored between the clearance volume (high pressure) and
crank case (low pressure). The channel is formed by preferably by
drilling one small hole with size range of about 3-5 mm on each
reed stopping deck along the cylinder wall to the depth of about
0.1 to about 0.3 mm under upper piston ring. This depth is very
critical. Too deep will cause the high pressure releasing too
earlier, which will cause efficiency lost. Too shallow will cause
the high pressure not be able to release in short time. Also,
several holes are drilled through the piston outside diameter
between the piston rings. When the piston completes the compression
stroke, a through channel is formed between the clearance volume
and the crank case from an opening on the cylinder bore deck that
is interconnected to openings on the outer diameter of the sides of
the piston between the piston rings. Because of the pressure
balance, when the channel is opened, the high pressure in the
clearance volume is released suddenly, and the new pressure will be
equal to suction pressure.
[0045] In an alternate embodiment, a channel is formed by drilling
a hole on the center of piston from the crankcase side with two
diameters: a smaller size for the opening and a bigger size for
remainder of the channel. A metal ball, spring, and set screw are
mounted at the opening. The diameter of opening on the piston is
smaller than the diameter of the metal ball, but the internal
diameter of the channel on the piston is bigger than the diameter
of metal ball. The transition between the sizes of the holes is
sphere-shaped to allow the ball to sit and seal.
[0046] When finishing assembling the ball, the spring, and a set
screw, through adjusting the set screw, it will push the spring to
apply a force to the ball, so that the ball is forced to sit on the
surface of sphere shape, and seal this through hole. The partial
ball extends from the top of the piston. When piston moves up and
down normally, the high pressure is not leaked from this hole and
the contact area between the ball and piston. When the piston
completes the compression stroke, the ball on the piston touches
the valve plate, and is squeezed down, thus the open channel is
formed. The clearance volume with high pressure above the piston is
connected with low pressure side. In this way, the high pressure is
released from the clearance volume.
[0047] The improvement is shown by the following examples relating
to the Figures:
[0048] In an embodiment depicted in FIGS. 1-4, the invention
provides a mechanism of raising the efficiency of the reciprocating
refrigeration compressor. As shown in FIG. 1, the mechanism
includes cylinder body 1, piston 2, suction reed 3 (see FIG. 3),
discharge reed 4, and valve plate 5. Two grooves 6 are milled along
the cylinder bore 7, located on each stopping deck 13 (see FIG. 2).
The grooves' 6 length is such that it allows high pressure in the
clearance volume 12 (see FIG. 4) to be released, and allow the
piston 2 to finish its compression stroke without losing high
pressure early which reduces the efficiency. Several holes 8 are
drilled through the piston 2 outside diameter between pressure ring
9 and oil ring 10. The holes 8 connect the outside diameter 2a of
the piston 2 to the low pressure side of the piston inside the
cylinder toward the crankcase 18. When the piston 2 completes the
compression stroke, a through channel 11 will be formed
automatically from the clearance volume 12 to the grooves 6 on the
cylinder bore stopping deck 13, then going through to the area
between two piston rings 9 & 10, finally through the holes 8 on
the piston 2 outside diameter 2a, flowing into the crankcase side
of the piston 18.
[0049] In an embodiment depicted in FIGS. 5 and 6, the groove 6 on
the cylinder bore deck 13 described above is replaced with an "L"
shaped duct 14. Ducts 14 are drilled on the cylinder stopping deck
13 parallel to the piston 2, and a second part of the duct 14a
perpendicular to the piston 2. The parts of the duct 14, 14a are
interconnected to form a shape substantially similar to a letter
"L". The second part of the duct 14a is situated to align with the
opening 15 of the channel 11 in the piston 2. The embodiment
performs in a similar fashion as described above.
[0050] In an embodiment depicted in FIGS. 7-11, a channel is formed
(preferably by drilling) on the center of the piston from the
crankcase side. The channel has two diameters: a smaller size for
at a first end 20, and a slightly bigger size for the remainder of
the channel 21. One metal ball 22, one spring 23, and one set screw
24 is mounted within the channel 21 of the piston 2 at the first
end 20. The diameter of the first end 20 on the top of the piston 2
must be smaller than the diameter of the metal ball 22, but
internal diameter of hole 21 on the piston 2 must be bigger than
the diameter of metal ball 22. The transition with two sizes first
end 20 and hole 21 will be sphere shape to allow the ball 22 to sit
and seal the first end 20.
[0051] As shown in FIGS. 9-11, when finishing assembling the ball
22, the spring 23, and a set screw 24, through adjusting the set
screw 24, it will push the spring to apply a force to the ball 22,
so that the ball 22 will be forced to sit on the surface of sphere
shape, and seal first end 20. The partial ball 22 will be out of
the top of the piston 2. When piston 2 moves up and down normally,
the high pressure would not be leaked from first end 20 and the
contact area between the ball 22 and piston 2. When the piston 2
completes the compression stroke, the ball 22 on the piston 2 will
touch the valve plate 5, and will be squeezed down, thus the open
channel will be formed automatically. The clearance volume with
high pressure above the piston 2 will be connected with low
pressure side. In this way, the high pressure will be released
then.
[0052] Accordingly, this invention is intended to embrace all
alternatives, modifications, and variations that fall within the
spirit and broad scope of the claims.
* * * * *