U.S. patent application number 14/461684 was filed with the patent office on 2014-12-25 for capacity modulation system for compressor and method.
The applicant listed for this patent is Emerson Climate Technologies, Inc.. Invention is credited to Ernest R. Bergman, Mitch M. Knapke, Frank S. Wallis.
Application Number | 20140377089 14/461684 |
Document ID | / |
Family ID | 40295529 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140377089 |
Kind Code |
A1 |
Wallis; Frank S. ; et
al. |
December 25, 2014 |
CAPACITY MODULATION SYSTEM FOR COMPRESSOR AND METHOD
Abstract
A compressor is provided and may include a first compression
mechanism, a first valve plate including a first port, and a first
manifold including a first cylinder having a first piston disposed
therein. The first piston may be movable between a first position
opening the first port and a second position closing the first
port. The compressor may additionally include a second compression
mechanism, a second valve plate including a second port, and a
second manifold including a second cylinder having a second piston
disposed therein. The second piston may be movable between a first
position opening the second port and a second position closing the
second port. A valve assembly may move one of the first and second
pistons into the first position while maintaining the other of the
first and second pistons in the second position.
Inventors: |
Wallis; Frank S.; (Sidney,
OH) ; Knapke; Mitch M.; (Maria Stein, OH) ;
Bergman; Ernest R.; (Rossburg, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Emerson Climate Technologies, Inc. |
Sidney |
OH |
US |
|
|
Family ID: |
40295529 |
Appl. No.: |
14/461684 |
Filed: |
August 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13426094 |
Mar 21, 2012 |
8807961 |
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14461684 |
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12177528 |
Jul 22, 2008 |
8157538 |
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13426094 |
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60951274 |
Jul 23, 2007 |
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Current U.S.
Class: |
417/298 |
Current CPC
Class: |
Y10T 137/2544 20150401;
F04B 49/03 20130101; F04B 39/1066 20130101; F04B 53/10 20130101;
F04B 49/225 20130101 |
Class at
Publication: |
417/298 |
International
Class: |
F04B 49/03 20060101
F04B049/03; F04B 39/10 20060101 F04B039/10 |
Claims
1. A compressor comprising: a first compression mechanism; a first
valve plate associated with said first compression mechanism and
including a first port; a first manifold disposed adjacent to said
first valve plate and including a first cylinder having a first
piston disposed therein, said first piston movable relative to said
first manifold between a first position separated from said first
valve plate opening said first port and a second position
contacting said first valve plate closing said first port; a second
compression mechanism; a second valve plate associated with said
second compression mechanism and including a second port; a second
manifold disposed adjacent to said second valve plate and including
a second cylinder having a second piston disposed therein, said
second piston movable relative to said second manifold between a
first position separated from said second valve plate opening said
second port and a second position contacting said second valve
plate closing said second port; and a valve assembly operable to
modulate a capacity of the compressor by moving said first piston
and said second piston between said first position and said second
position, said valve assembly moving one of said first piston and
said second piston into said first position while maintaining the
other of said first piston and said second piston in said second
position.
2. The compressor of claim 1, wherein said one of said first piston
and said second piston is duty-cycle controlled by said valve
assembly.
3. The compressor of claim 2, wherein said other of said first
piston and said second piston is in said second position when said
one of said first piston and said second piston is duty-cycle
controlled by said valve assembly.
4. The compressor of claim 2, wherein said valve assembly includes
a first solenoid valve associated with said first piston and a
second solenoid valve associated with said second piston.
5. The compressor of claim 1, wherein said first piston includes a
first valve element disposed therein and movable relative to said
first piston and said second piston includes a second valve element
disposed therein and movable relative to said second piston, said
first valve element and said second valve element respectively
contacting said first valve plate and said second valve plate when
said first piston and said second piston are in said second
position.
6. The compressor of claim 5, wherein said first piston and said
second piston each include an inner volume having a pressurized
fluid disposed therein, said pressurized fluid operable to bias
said valve elements toward respective ends of said first piston and
said second piston.
7. The compressor of claim 1, further comprising a first chamber
disposed between a top surface of said first piston and an inner
surface of said first cylinder and a second chamber disposed
between a top surface of said second piston and an inner surface of
said second cylinder, said first chamber and said second chamber
selectively receiving a pressurized fluid to move said first piston
and said second piston from said first position to said second
position.
8. The compressor of claim 7, wherein said valve assembly
selectively supplies said pressurized fluid to said first chamber
and said second chamber.
9. The compressor of claim 8, wherein said valve assembly supplies
said pressurized fluid to said first chamber to cycle said first
piston between said first position and said second position at a
predetermined duty cycle while maintaining said second piston in
said first position.
10. The compressor of claim 8, wherein said valve assembly supplies
said pressurized fluid to said first chamber to cycle said first
piston between said first position and said second position at a
predetermined duty cycle while maintaining said second piston in
said second position.
11. A compressor comprising: a first compression mechanism; a first
valve plate associated with said first compression mechanism and
including a first port; a first manifold disposed adjacent to said
first valve plate and including a first cylinder having a first
piston disposed therein, said first piston movable relative to said
first manifold between a first position separated from said first
valve plate opening said first port and a second position
contacting said first valve plate closing said first port; a second
compression mechanism; a second valve plate associated with said
second compression mechanism and including a second port; a second
manifold disposed adjacent to said second valve plate and including
a second cylinder having a second piston disposed therein, said
second piston movable relative to said second manifold between a
first position separated from said second valve plate opening said
second port and a second position contacting said second valve
plate closing said second port; and a valve assembly operable to
modulate a capacity of the compressor by moving said first piston
and said second piston between said first position and said second
position, said valve assembly cycling one of said first piston and
said second piston between said first position and said second
position at a predetermined duty cycle while maintaining the other
of said first piston and said second piston in one of said first
position and said second position.
12. The compressor of claim 11, wherein said valve assembly
includes a first solenoid valve associated with said first piston
and a second solenoid valve associated with said second piston.
13. The compressor of claim 11, wherein said first piston includes
a first valve element disposed therein and movable relative to said
first piston and said second piston includes a second valve element
disposed therein and movable relative to said second piston, said
first valve element and said second valve element respectively
contacting said first valve plate and said second valve plate when
said first piston and said second piston are in said second
position.
14. The compressor of claim 13, wherein said first piston and said
second piston each include an inner volume having a pressurized
fluid disposed therein, said pressurized fluid operable to bias
said valve elements toward respective ends of said first piston and
said second piston.
15. The compressor of claim 11, further comprising a first chamber
disposed between a top surface of said first piston and an inner
surface of said first cylinder and a second chamber disposed
between a top surface of said second piston and an inner surface of
said second cylinder, said first chamber and said second chamber
selectively receiving a pressurized fluid to move said first piston
and said second piston from said first position to said second
position.
16. The compressor of claim 15, wherein said valve assembly
selectively supplies said pressurized fluid to said first chamber
and said second chamber.
17. The compressor of claim 16, wherein said valve assembly
supplies said pressurized fluid to said first chamber to cycle said
first piston between said first position and said second position
at said predetermined duty cycle while maintaining said second
piston in said first position.
18. The compressor of claim 16, wherein said valve assembly
supplies said pressurized fluid to said first chamber to cycle said
first piston between said first position and said second position
at said predetermined duty cycle while maintaining said second
piston in said second position.
19. A compressor comprising: a first compression mechanism; a first
valve plate associated with said first compression mechanism and
including a first port; a first manifold disposed adjacent to said
first valve plate and including a first cylinder having a first
piston disposed therein, said first piston movable relative to said
first manifold between a first position separated from said first
valve plate opening said first port and a second position
contacting said first valve plate closing said first port; a second
compression mechanism; a second valve plate associated with said
second compression mechanism and including a second port; a second
manifold disposed adjacent to said second valve plate and including
a second cylinder having a second piston disposed therein, said
second piston movable relative to said second manifold between a
first position separated from said second valve plate opening said
second port and a second position contacting said second valve
plate closing said second port; and a valve assembly operable to
modulate a capacity of the compressor by moving said first piston
and said second piston between said first position and said second
position, said valve assembly moving said first piston between said
first position and said second position using a first capacity
modulation method and moving said second piston between said first
position and said second position using a second capacity
modulation method independent from said first capacity modulation
method.
20. The compressor of claim 19, wherein said valve assembly
includes a first solenoid valve associated with said first piston
and a second solenoid valve associated with said second piston.
21. The compressor of claim 19, wherein said first piston includes
a first valve element disposed therein and movable relative to said
first piston and said second piston includes a second valve element
disposed therein and movable relative to said second piston, said
first valve element and said second valve element respectively
contacting said first valve plate and said second valve plate when
said first piston and said second piston are in said second
position.
22. The compressor of claim 21, wherein said first piston and said
second piston each include an inner volume having a pressurized
fluid disposed therein, said pressurized fluid operable to bias
said valve elements toward respective ends of said first piston and
said second piston.
23. The compressor of claim 19, further comprising a first chamber
disposed between a top surface of said first piston and an inner
surface of said first cylinder and a second chamber disposed
between a top surface of said second piston and an inner surface of
said second cylinder, said first chamber and said second chamber
selectively receiving a pressurized fluid to move said first piston
and said second piston from said first position to said second
position.
24. The compressor of claim 23, wherein said valve assembly
selectively supplies said pressurized fluid to said first chamber
and said second chamber.
25. The compressor of claim 24, wherein said first capacity
modulation method includes said valve assembly supplying said
pressurized fluid to said first chamber to cycle said first piston
between said first position and said second position at a
predetermined duty cycle and said second capacity modulation method
includes maintaining said second piston in said first position.
26. The compressor of claim 24, wherein said first capacity
modulation method includes said valve assembly supplying said
pressurized fluid to said first chamber to cycle said first piston
between said first position and said second position at a
predetermined duty cycle and said second capacity modulation method
includes maintaining said second piston in said second
position.
27. The compressor of claim 19, wherein said first capacity
modulation method includes cycling said first piston between said
first position and said second position at a predetermined duty
cycle and said second capacity modulation method includes
maintaining said second piston in said first position.
28. The compressor of claim 19, wherein said first capacity
modulation method includes cycling said first piston between said
first position and said second position at a predetermined duty
cycle and said second capacity modulation method includes
maintaining said second piston in said second position.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/426,094 filed on Mar. 21, 2012, which is a
continuation of U.S. patent application Ser. No. 12/177,528 filed
on Jul. 22, 2008 (now U.S. Pat. No. 8,157,538), which claims the
benefit of U.S. Provisional Application No. 60/951,274 filed on
Jul. 23, 2007. The disclosures of the above applications are
incorporated herein by reference.
FIELD
[0002] The present disclosure relates generally to compressors and
more particularly to a capacity modulation system and method for a
compressor.
BACKGROUND
[0003] Heat pump and refrigeration systems are commonly operated
under a wide range of loading conditions due to changing
environmental conditions. In order to effectively and efficiently
accomplish a desired cooling and/or heating under these changing
conditions, conventional heat pump or refrigeration systems may
incorporate a compressor having a capacity modulation system that
adjusts an output of the compressor based on the environmental
conditions.
SUMMARY
[0004] A compressor is provided and may include a first compression
mechanism, a first valve plate associated with the first
compression mechanism and including a first port, and a first
manifold disposed adjacent to the first valve plate and including a
first cylinder having a first piston disposed therein. The first
piston may be movable relative to the first manifold between a
first position separated from the first valve plate opening the
first port and a second position contacting the first valve plate
closing the first port. The compressor may additionally include a
second compression mechanism, a second valve plate associated with
the second compression mechanism and including a second port, and a
second manifold disposed adjacent to the second valve plate and
including a second cylinder having a second piston disposed
therein. The second piston may be movable relative to the second
manifold between a first position separated from the second valve
plate opening the second port and a second position contacting the
second valve plate closing the second port. A valve assembly may
modulate a capacity of the compressor by moving the first piston
and the second piston between the first position and the second
position, whereby the valve assembly moves one of the first piston
and the second piston into the first position while maintaining the
other of the first piston and the second position in the second
position.
[0005] In another configuration, a compressor is provided and may
include a first compression mechanism, a first valve plate
associated with the first compression mechanism and including a
first port, and a first manifold disposed adjacent to the first
valve plate and including a first cylinder having a first piston
disposed therein. The first piston may be movable relative to the
first manifold between a first position separated from the first
valve plate opening the first port and a second position contacting
the first valve plate closing the first port. The compressor may
additionally include a second compression mechanism, a second valve
plate associated with the second compression mechanism and
including a second port, and a second manifold disposed adjacent to
the second valve plate and including a second cylinder having a
second piston disposed therein. The second piston may be movable
relative to the second manifold between a first position separated
from the second valve plate opening the second port and a second
position contacting the second valve plate closing the second port.
A valve assembly may modulate a capacity of the compressor by
moving the first piston and the second piston between the first
position and the second position, whereby the valve assembly cycles
one of the first piston and the second piston between the first
position and the second position at a predetermined duty cycle
while maintaining the other of the first piston and the second
piston in one of the first position and the second position.
[0006] In yet another configuration, a compressor is provided and
may include a first compression mechanism, a first valve plate
associated with the first compression mechanism and including a
first port, and a first manifold disposed adjacent to the first
valve plate and including a first cylinder having a first piston
disposed therein. The first piston may be movable relative to the
first manifold between a first position separated from the first
valve plate opening the first port and a second position contacting
the first valve plate closing the first port. The compressor may
additionally include a second compression mechanism, a second valve
plate associated with the second compression mechanism and
including a second port, and a second manifold disposed adjacent to
the second valve plate and including a second cylinder having a
second piston disposed therein. The second piston may be movable
relative to the second manifold between a first position separated
from the second valve plate opening the second port and a second
position contacting the second valve plate closing the second port.
A valve assembly may modulate a capacity of the compressor by
moving the first piston and the second piston between the first
position and the second position. The valve assembly may move the
first piston between the first position and the second position
using a first capacity modulation method and may move the second
piston between the first position and the second position using a
second capacity modulation method independent from the first
capacity modulation method.
[0007] A method is provided and may include modulating a capacity
of a first cylinder of a reciprocating compressor using a first
capacity modulation method and modulating a capacity of a second
cylinder of the reciprocating compressor using a second capacity
modulation method different than the first capacity modulation
method.
[0008] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
DRAWINGS
[0009] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
[0010] FIG. 1 is a cross-sectional view of a compressor
incorporating a valve apparatus according to the present disclosure
shown in a closed position;
[0011] FIG. 2 is a perspective view of the valve apparatus of FIG.
1;
[0012] FIG. 3 is a cross-sectional view of the valve apparatus of
FIG. 1 shown in an open position;
[0013] FIG. 4 is a perspective view of the valve apparatus of FIG.
3;
[0014] FIG. 5 is a cross-sectional view of a pressure-responsive
valve member shown in a first position;
[0015] FIG. 6 is a cross-sectional view of the pressure-responsive
valve member of FIG. 5 shown in a second position;
[0016] FIG. 7 is a cross-sectional view of a pressure-responsive
valve member according to the present disclosure shown in a closed
position;
[0017] FIG. 8 is a cross-sectional view of a pressure-responsive
valve according to the present disclosure shown in a first
position;
[0018] FIG. 9 is a cross-sectional view of the pressure-responsive
valve of FIG. 8 shown in a second position;
[0019] FIG. 10 is a cross-sectional view of a compressor and valve
apparatus according to the present disclosure shown in a closed
position and opened position; and
[0020] FIG. 11 is a schematic view of a compressor in combination
with a valve apparatus according to the present disclosure.
DETAILED DESCRIPTION
[0021] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses. It should be understood that throughout the drawings,
corresponding reference numerals indicate like or corresponding
parts and features. The present teachings are suitable for
incorporation in many different types of scroll and rotary
compressors, including hermetic machines, open drive machines and
non-hermetic machines.
[0022] Various embodiments of a valve apparatus are disclosed that
allow or prohibit fluid flow, and may be used to modulate fluid
flow to a compressor, for example. The valve apparatus includes a
chamber having a piston slidably disposed therein, and a control
pressure passage in communication with the chamber. A control
pressure communicated to the chamber biases the piston for moving
the piston relative to a valve opening, to thereby allow or
prohibit fluid communication through the valve opening. When
pressurized fluid is communicated to the chamber, the piston is
biased to move against the valve opening, and may be used for
blocking fluid flow to a suction inlet of a compressor, for
example. The valve apparatus may be a separate component that is
spaced apart from but fluidly coupled to an inlet of a compressor,
or may alternatively be a component included within a compressor
assembly. The valve apparatus may be operated together with a
compressor, for example, as an independent unit that may be
controlled by communication of a control pressure via an external
flow control device. The valve apparatus may also optionally
include a pressure-responsive valve member and a solenoid valve, to
selectively provide for communication of a high or low control
pressure fluid to the control pressure passage.
[0023] Referring to FIG. 1, a pressure-responsive valve apparatus
or unloader valve 100 is shown including a chamber 120 having a
piston assembly 110 disposed therein, which moves relative to an
opening 106 in a valve plate 107 to control fluid flow
therethrough. The piston 110 may be moved by communication of a
control pressure to the chamber 120 in which the piston 110 is
disposed. The control pressure may be one of a low pressure and a
high pressure, which may be communicated to the chamber 120 by a
valve, for example. To selectively provide a high or low control
pressure, the valve apparatus 100 may optionally include a
pressure-responsive valve member and a solenoid valve, which will
be described later.
[0024] As shown in FIGS. 1 and 2, the piston 110 is capable of
prohibiting fluid flow through the valve apparatus 100, and may be
used for blocking fluid flow to a passage 104 in communication with
the suction inlet of a compressor 10. While the valve apparatus 100
will be described hereinafter as being associated with a compressor
10, the valve apparatus 100 could also be associated with a pump,
or used in other applications to control fluid flow.
[0025] The compressor 10 is shown in FIGS. 1, 10, and 11 and may
include a manifold 12, a compression mechanism 14, and a discharge
assembly 16. The manifold 12 may be disposed in close proximity to
the valve plate 107 and may include at least one suction chamber
18. The compression mechanism 14 may similarly be disposed within
the manifold 12 and may include at least one piston 22 received
generally within a cylinder 24 formed in the manifold 12. The
discharge assembly 18 may be disposed at an outlet of the cylinder
24 and may include a discharge-valve 26 that controls a flow of
discharge-pressure gas from the cylinder 24.
[0026] The chamber 120 is formed in a body 102 of the valve
apparatus 100 and slidably receives the piston 110 therein. The
valve plate 107 may include a passage 104 formed therein and in
selective communication with the valve opening 106. The passage 104
of the valve apparatus 100 may provide for communication of fluid
to an inlet of the compressor 10, for example. The body 102 may
include a control-pressure passage 124, which is in communication
with the chamber 120. A control pressure may be communicated via
the control-pressure passage 124 to chamber 120, to move the piston
110 relative to the valve opening 106. The body 102 may be
positioned relative to the compression mechanism 14 such that the
valve plate 107 is disposed generally between the compression
mechanism 14 and the body 102 (FIGS. 1, 10, and 11).
[0027] When a pressurized fluid is communicated to the chamber 120,
the piston 110 moves against valve opening 106 to prohibit fluid
flow therethrough. In an application where the piston 110 blocks
fluid flow to a suction inlet of a compressor 10 for "unloading"
the compressor, the piston 110 may be referred to as an unloader
piston. In such a compressor application, the pressurized fluid may
be provided by the discharge-pressure gas of the compressor 10.
Suction-pressure gas from the suction chamber 18 of the compressor
10 may also be communicated to the chamber 120, to bias the piston
110 away from the valve opening 106. Accordingly, the piston 110 is
movable relative to the valve opening 106 to allow or prohibit
fluid communication to passage 104.
[0028] With continued reference to FIG. 1, the piston 110 is moved
by application of a control pressure to a chamber 120 in which the
piston 110 is disposed. The volume within opening 106, generally
beneath the piston 110 at 182, is at low pressure or suction
pressure, and may be in communication with a suction-pressure gas
of a compressor, for example. When the chamber 120 above the piston
110 is at a higher relative pressure than the area under the piston
110, the relative pressure difference causes the piston 110 to be
urged in a downward direction within the chamber 120.
[0029] An O-ring seal 134 may be provided in an insert 136
installed in a wall 121 of the chamber 120 to provide a seal
between the pressurized fluid within the chamber 120 and the low
pressure passage 104. The chamber wall 121 may be integrally formed
with the insert 136, thereby eliminate the need for the O-ring seal
134.
[0030] The piston 110 is pushed down by the difference in pressure
above and below the piston 110 and by the pressure acting on an
area defined by a diameter of a seal B. Accordingly, communication
of discharge-pressure gas to the chamber 120 generally above the
piston 110 causes the piston 110 to move toward and seal the valve
opening 106.
[0031] The piston 110 may further include a disc-shaped sealing
element 140 disposed at an open end of the piston 110. Blocking off
fluid flow through the opening 106 is achieved when a valve seat
108 at opening 106 is engaged by the disc-shaped sealing element
140 disposed on the lower end of the piston 110.
[0032] The piston 110 may include a piston cylinder 114 with a plug
116 disposed therein proximate to an upper-end portion of the
piston cylinder 114. The plug 116 may alternatively be integrally
formed with the piston cylinder 114. The piston cylinder 114 may
include a retaining member or lip 118 that retains the disc-shaped
sealing element 140, a seal C, and a seal carrier or disk 142
within the lower end of the piston 110. A pressurized fluid (such
as discharge-pressure gas, for example) may be communicated to the
interior of the piston 110 through a port P. The sealing element
140 is moved into engagement with the valve seat 108 by the applied
discharge-pressure gas at port P, which is trapped within the
piston 110 by seal C. Specifically, the pressurized fluid inside
the piston 110 biases the seal carrier 142 downward, which
compresses seal C against the disc-shaped sealing element 140. The
seal carrier 142, seal C, and the disc-shaped sealing element 140
are moveable within the lower end of the piston cylinder 114 by the
discharge-pressure gas disposed within the piston 110. As described
above, movement of the piston 110 into engagement with the valve
seat 108 prevents flow through the valve opening 106.
[0033] As shown in FIG. 1, the piston 110 has a disc-shaped sealing
element 140 slidably disposed in a lower portion of the piston 110.
The retaining member 118 is disposed at the lower portion of the
piston 110, and engages the disc-shaped sealing element 140 to
retain the sealing element 140 within the lower end portion of the
piston 110. The slidable arrangement of the sealing element 140
within the piston 110 permits movement of the sealing element 140
relative to the piston 110 when the sealing element 140 closes off
the valve opening 106. When discharge-pressure gas is communicated
to the chamber 120, the force of the discharge-pressure gas acting
on the top of the piston 110 causes the piston 110 and sealing
element 140 to move towards the raised valve seat 108 adjacent the
valve opening 106. The high pressure gas disposed above the piston
110 and low-pressure gas disposed under the piston 110 (in the area
defined by the valve seat 108) thereby pushes the piston 110 down.
The disc-shaped sealing element 140 is held down against the valve
opening 106 by the discharge-pressure gas applied on top of the
disc-shaped sealing element 140. Suction-pressure gas is also
disposed under the sealing element 140 at the annulus between the
seal C and valve seat 108.
[0034] As shown in FIG. 1, the thickness of the retaining member
118 is less than the height of the valve seat 108. The relative
difference between the height of the retaining member 118 and the
valve seat 108 is such that the sealing element 140 engages and
closes off the valve seat 108 before the bottom of the piston 110
reaches the valve plate 107 in which the valve opening 106 and
valve seat 108 are located. Specifically, the height of the
retaining member or lip 118 is less than the height of the valve
seat 108, such that when the sealing element 140 engages the valve
seat 108, the retaining member 118 has not yet engaged the valve
plate 107. The piston 110 may then continue to move or travel over
and beyond the point of closure of the sealing element 140 against
the valve seat 108, to a position where the retaining element 118
engages the valve plate 107.
[0035] The above "over-travel" distance is the distance that the
piston 110 may travel beyond the point the sealing element 140
engages and becomes stationary against the valve seat 108, before
the retaining member 118 seats against the valve plate 107. This
"over-travel" of the piston 110 results in relative movement
between the piston 110 and the sealing element 140. Such relative
movement results in the displacement of the seal C and seal carrier
142 against the pressure within the inside of the piston 110, which
provides a force for holding the sealing element 140 against the
valve seat 108. The amount of "over-travel" movement of the piston
cylinder 114 relative to the sealing disc element 140 may result in
a slight separation (or distance) D between the retaining member
118 and the sealing element 140, as shown in FIG. 1. In one
configuration, the amount of over travel may be in the range of
0.001 to 0.040 inches, with a nominal of 0.020 inches.
[0036] The valve plate 107 arrests further movement of the piston
110 and absorbs the impact associated with the momentum of the mass
of the piston 110 (less the mass of the stationary seal carrier
142, seal C, and sealing element 140). Specifically, the piston 110
is arrested by the retaining member 118 impacting against the valve
plate 107 rather than against the then-stationary sealing element
140 seated on the valve seat 108. Thus, the sealing element 140
does not experience any impact imparted by the piston 110, thereby
reducing damage to the sealing element 140 and extending the useful
life of the valve apparatus 100. The kinetic energy of the moving
piston 110 is therefore absorbed by the valve plate 107 rather than
the sealing element 140 disposed on the piston 110.
[0037] The piston 110, including the sealing element 140, lends
itself to applications where repetitive closure occurs, such as,
for example, in duty-cycle modulation of flow to a pump, or suction
flow to a compressor for controlling compressor capacity. By way of
example, the mass of the piston assembly 110 may be as much as 47
grams, while the sealing element 140, seal carrier 142, and seal C
may have a mass of only 1.3 grams, 3.7 grams and 0.7 grams
respectively. By limiting the mass that will impact against the
valve seat 108 to only the mass of the sealing element 140, seal
carrier 142, and seal C, the seal element 140 and valve seat 108
avoid absorbing the kinetic energy associated with the much greater
mass of the piston assembly 110. This feature reduces the potential
for damage to the sealing element 140, and provides for extending
valve function from about 1 million cycles to over 40 million
cycles of operation. The piston 110 also provides improved
retraction or upward movement of the piston 110, as will be
described below.
[0038] Referring to FIGS. 3 and 4, the piston 110 is shown in the
open state relative to the valve opening 106. Chamber 120 may be
placed in communication with a low pressure fluid source (such as
suction pressure gas from a compressor, for example) to allow the
piston 110 to move away from the valve opening 106 and permit
suction flow therethrough. A valve member 126 (shown in FIGS. 5 and
6) must move to the second position in order to supply low pressure
gas into control-pressure passage 124 and chamber 120. Only after
low pressure gas (e.g., suction pressure gas) is in chamber 120
will the piston 110 be urged upward. In other words, high pressure
gas is trapped in chamber 120 until the chamber 120 is vented to
suction pressure by the movement of valve member 126 into the
second position. The piston 110 is maintained in the open state
while a low pressure or suction pressure is communicated to the
chamber 120. In this state, the piston 110 is positioned for full
capacity, with suction gas flowing unrestricted through valve
opening 106 and into a suction passage 104 within the valve plate
107. Suction-pressure gas in communication with the chamber 120
above the piston 110 allows the piston 110 to move in an upward
direction relative to the body 102. Suction-pressure gas may be in
communication with the chamber 120 via the suction passage 104 in
the valve plate 107.
[0039] The piston 110 may be moved away from the valve opening 106
by providing a pressurized fluid to a control volume or passage 122
that causes the piston 110 to be biased in an upward direction as
shown in FIG. 3. The seals A and B positioned between the piston
110 and chamber 120 together are configured to define a volume 122
therebetween that, when pressurized, causes the piston 110 to move
upward and away from the valve opening 106. Specifically, the
mating surfaces of the piston 110 and chamber 120 are configured to
define a volume 122 therebetween that is maintained in a sealed
manner by an upper seal A and lower seal B. The piston 110 may
further include a shoulder surface 112 against which pressurized
fluid disposed within the volume 122 and between seals A and B
expands and pushes against the shoulder 112 to move the piston 110
within the chamber 120.
[0040] Seal A serves to keep pressurized fluid within the volume
122 between the chamber 120 and piston 110 from escaping to the
chamber 120 above the piston 110. In one configuration,
discharge-pressure gas is supplied through passage 111 and orifice
113 which feeds the volume 122 bounded by seal A and seal B between
the piston 110 and chamber 120. The volume on the outside of the
piston 110, trapped by seal A and seal B, is always charged with
discharge-pressure gas, thereby providing a lifting force when
suction-pressure gas is disposed above piston 110 and within a top
portion of the chamber 120 proximate to control-pressure passage
124. Using gas pressure exclusively to lift and lower the piston
110 eliminates the need for springs and the disadvantages
associated with such springs (e.g., fatigue limits, wear and piston
side forces, for example). While a single piston 110 is described,
a valve apparatus 100 having multiple pistons 110 (i.e., operating
in parallel, for example) may be employed where a compressor or
pump includes multiple suction paths.
[0041] The valve apparatus 100 may be a separate component that is
spaced apart from but fluidly coupled to an inlet of a compressor,
or may alternatively be attached to a compressor (not shown). The
valve apparatus 100 may be operated together with a compressor, for
example, as an independent unit that may be controlled by
communication of a control pressure via an external flow control
device. It should be noted that various flow control devices may be
employed for selectively communicating one of a suction-pressure
gas and a discharge-pressure gas to the control-pressure passage
124 to move the piston 110 relative to the opening 106.
[0042] Referring to FIGS. 5 and 6, the valve apparatus 100 may
further include a pressure-responsive valve member 126 proximate
the control-pressure passage 124. The pressure-responsive valve
member 126 may communicate a control pressure to the
control-pressure passage 124 to move the piston 110, as previously
discussed above. The valve member 126 is movable between first and
second positions in response to the communication of pressurized
fluid to the valve member 126. When a pressurized fluid is
communicated to the valve member 126, the valve member 126 may be
moved to the first position to permit communication of
high-pressure gas to the control-pressure passage 124 to urge the
piston 110 to a closed position. The pressurized fluid may be a
discharge pressure gas from a compressor, for example. In the first
position, the valve member 126 may also prohibit fluid
communication between the control-pressure passage 124 and a low
pressure or suction-pressure passage 186.
[0043] In the absence of pressurized fluid, the valve member 126 is
moved to a second position where fluid communication between the
control-pressure passage 124 and the suction-pressure passage 186
is permitted. The suction-pressure may be provided by communication
with a suction line of a compressor, for example. The valve member
126 (shown in FIGS. 5 and 6) must move to the second position in
order to supply low pressure gas into control-pressure passage 124
and chamber 120. Only after low pressure gas (e.g., suction
pressure gas, for example) is in chamber 120 will the piston 110 be
urged upward. In other words, high pressure gas is trapped in
chamber 120 until it is vented to suction pressure by the movement
of valve member 126 into the second position. The valve member 126
is movable between the first position where fluid communication
between the control-pressure passage 124 and the suction-pressure
passage 186 is prohibited and the second position where fluid
communication between the control-pressure passage 124 and
suction-pressure passage 186 is permitted. Accordingly, the valve
member 126 is selectively moveable for communicating one of the
suction-pressure gas and discharge-pressure gas to the
control-pressure passage 124.
[0044] The valve member 126 is movable between the first position
shown in FIG. 5, and the second position shown in FIG. 6, depending
on the application of high-pressure gas to the valve member 126.
When the valve member 126 is in communication with a pressurized
fluid, the valve member 126 moved to the first position, as shown
in FIG. 5. The pressurized fluid may be a discharge pressure gas
from a compressor, for example.
[0045] As shown in FIG. 5, the valve member 126 includes a
pressure-responsive slave piston 160 and seal seat 168. The slave
piston 160 responds to a high-pressure input (such as discharge
pressure gas from a compressor, for example), by moving downward
against a seal surface 166. The pressure-responsive valve member
126 includes the slave piston 160, a spring 162 for spring-loading
a check valve or ball 164, a sealing surface 166 and mating seal
seat 168, common port 170, a seal 172 on the slave piston outside
diameter, and a vent orifice 174. Operation of the slave piston 160
is described below.
[0046] The slave piston 160 remains seated against a seal surface
166 when a pressurized fluid is in communication with the slave
piston 160. The pressurized fluid may be a discharge pressure gas
from a compressor, for example. When pressurized fluid is in
communication with the volume above the slave piston 160, the
pressurized fluid is allowed to flow through the
pressure-responsive slave piston 160 via hole 178 in the center of
the slave piston 160 and past the check-valve ball 164. This
pressurized fluid, which is at or near discharge pressure, is
communicated to the chamber 120 for pushing the piston 110 down
against valve opening 106, as previously explained, such that
suction flow is blocked and the compressor 10 is "unloaded." There
is a pressure-drop past the check-valve ball 164, as a result of
the pressurized fluid acting to overcome the force of the spring
162 biasing the check-valve ball 164 away from the hole 178. This
pressure differential across the slave piston 160 is enough to push
the slave piston 160 down against surface 166 to provide a seal.
This seal effectively traps or restricts high pressure gas to the
common port 170 leading to the control-pressure passage 124. The
control-pressure passage 124 may be in communication with one or
more chambers 120 for opening or closing one or more pistons 110.
The common port 170 and control-pressure passage 124 directs
discharge-pressure gas to chamber 120 against the piston 110, to
thereby push the piston 110 down.
[0047] As long as high pressure (i.e., higher than system-suction
pressure) exists above the slave piston 160, leakage occurs past
the vent orifice 174. The vent orifice 174 is small enough to have
a negligible effect on the system operating efficiency while
leakage occurs past the vent orifice 174. The vent orifice 174 may
include a diameter that is large enough to prevent clogging by
debris and small enough to at least partially restrict flow
therethrough to tailor an efficiency of the system. In one
configuration, the vent orifice 174 may include a diameter of
approximately 0.04 inches. The vent orifice 174 discharges upstream
of the piston 110 at point 182 (see FIG. 1), so that the pressure
downstream of the piston 110 at passage 104 remains substantially
at vacuum. Specifically, when pressurized fluid flow pushes the
piston 110 closed to block flow through valve opening 106, the
fluid bleeding through the vent orifice 174 discharges through a
suction passage 180 to a location 182 (see FIG. 1) on the closed or
blocked side of the piston 110. The discharged fluid that is bled
away through vent orifice 174 is blocked by the piston 110, and is
not communicated through passage 104. Where the valve apparatus 100
controls fluid flow to a suction inlet of a compressor 10, for
example, the absence of vented fluid flow through passage 104 to
the compressor 10 would reduce power consumption of the compressor
10. Venting of discharge gas upstream of the piston 110 reduces
power consumption of the compressor 10 by allowing the pressure
downstream of the piston 110 to more quickly drop into a
vacuum.
[0048] Referring to FIG. 6, the slave piston 160 (or valve member
126) is shown in a second position, where communication of
pressurized fluid or discharge-pressure gas to the slave piston 160
is prohibited. In this position, the valve chamber is in
communication with the suction-pressure passage 186, such that the
piston 110 is moved into the "loaded" position. The internal volume
of the chamber or passage 184 between the solenoid valve 130 and
the slave piston 160 is as small as practical (considering design
and economic limitations), such that the amount of trapped
pressurized fluid therein may be bled off quickly to effectuate a
fast closure of the piston 110. When communication of pressurized
fluid to the slave piston 160 is discontinued, the pressure trapped
above the slave piston bleeds past the vent orifice 174. As the
pressure drops above the slave piston 160 the check valve 164 is
closed against hole 178, which prevents pressure in the common port
170 from flowing into the chamber above the slave piston 160. The
common port 170 that feeds the chamber 120 above the piston 110 may
also be referred to as the "common" port, particularly where the
valve apparatus 100 includes a plurality of pistons 110.
[0049] There is a pressure balance point across the slave piston
160, whereby bleed-off through the vent orifice 174 causes further
lowering of top-side pressure and lifts the slave piston 160
upwards, unseating the slave piston 160 from the seal surface 166.
At this point, pressure in the common port 170 is vented across the
slave piston seal seat 168 and into the suction-pressure passage
186. The suction-pressure passage 186 establishes communication of
suction pressure through the common port 170 to the chamber 120,
and the piston 110 then lifts when the pressure on top of the
piston 110 drops. Additionally, the use of a pressure drop across
the slave piston's check valve 164 (in the un-checked direction)
will serve to reduce the amount of fluid mass needed to push the
piston 110 down.
[0050] Use of a slave piston 160 to drive the piston 110 provides
for rapid response of the piston 110. The response time of the
valve apparatus 100 is a function of the size of the vent orifice
174 and the volume above the slave piston 160 in which pressurized
fluid is trapped. Where the valve apparatus 100 controls fluid flow
to a suction inlet of a compressor 10, for example, reducing the
volume of the common port 170 will improve response time and
require less usage of refrigerant per cycle to modulate the
compressor. While the above pressure-responsive slave piston 160 is
suitable for selectively providing one of a discharge-pressure gas
or a suction-pressure gas to a control-pressure passage 124, other
alternative means for providing a pressure-responsive valve member
may be used in place of the above, as described below.
[0051] Referring to FIG. 7, an alternate construction of a
pressure-responsive valve 200 is shown in which the slave piston
160 of the first embodiment is replaced by a diaphragm valve 260.
As shown in FIG. 7, the valve member or diaphragm 260 is spaced
apart from the sealing surface 166 such that suction-pressure gas
in passage 186 is in communication with common port 170 and
control-pressure passage 124 for biasing the piston 110 to an open
position. Communication of pressurized fluid (i.e.,
discharge-pressure gas) to the top side of the diaphragm 260 causes
the diaphragm 260 to move down and seal against the sealing surface
166 to prohibit communication of suction-pressure gas at 186 to the
control-pressure passage 124. The pressurized fluid also displaces
the check valve 164 to establish communication of pressurized fluid
to the common port 170 and control-pressure passage 124, to thereby
move the piston 110 into a closed position. In this construction,
the common port 170 is disposed under the diaphragm valve 260, and
the suction-pressure passage 186 is disposed under the middle of
the diaphragm valve 260. The fundamental concept of operation is
the same as the valve embodiment shown in FIG. 6.
[0052] A valve apparatus 100 including the above
pressure-responsive valve member 126 may be operated together with
a compressor, for example, as an independent unit that may be
controlled by communication of pressurized fluid (i.e., discharge
pressure) to the pressure-responsive valve member 126. It should be
noted that various flow control devices may be employed for
selectively allowing or prohibiting communication of discharge
pressure to the pressure-responsive valve member.
[0053] The valve apparatus 100 may further include a solenoid valve
130, for selectively allowing or prohibiting communication of
discharge-pressure gas to the pressure-responsive valve member
126.
[0054] Referring to FIGS. 5-9, a solenoid valve 130 is provided
that is in communication with a pressurized fluid. The pressurized
fluid may be a discharge pressure gas from the compressor 10, for
example. The solenoid valve 130 is movable to allow or prohibit
communication of pressurized fluid to the valve member 126 or slave
piston 160. The solenoid valve 130 functions as a two-port (on/off)
valve for establishing and discontinuing communication of
discharge-pressure gas to the slave piston 160, which responds as
previously described.
[0055] In connection with the pressure-responsive valve member 126,
the solenoid valve 130 substantially has the output functionality
of a three-port solenoid valve (i.e., suction-pressure gas or
discharge-pressure gas may be directed to the common port 170 or
control-pressure passage 124 to raise or lower the piston 110).
When the solenoid valve 130 is energized (via wires 132) to an open
position, the solenoid valve 130 establishes communication of
discharge-pressure gas to the slave piston 160. The slave piston
160 is responsively moved to a first position where it is seated
against a seal surface 166, as previously described and shown in
FIG. 5. While the solenoid valve 130 is energized and
discharge-pressure gas is communicated to the slave piston 160 and
chamber 120, the piston 110 closes the suction gas flow passage 186
in the vicinity of the opening 106 in the valve plate 107. When the
solenoid valve 130 is de-energized to prohibit communication of
pressurized fluid, the slave piston 160 moves to the second
position where communication of suction pressure is established
with the control-pressure passage 124 and chamber 120. As
previously described, suction pressure in communication with the
chamber 120 above the piston 110 biases the piston 110 in an upward
direction. While the solenoid valve 130 is de-energized and suction
pressure is communicated to the control-pressure passage 124, the
piston 110 is positioned for full capacity with suction gas flowing
unrestricted through valve opening 106 into a suction passage 128.
Suction-pressure gas is in communication with the chamber 120 via
the suction passage 128 in the valve plate 107.
[0056] Referring to FIGS. 8 and 9, a pressure-responsive valve 300
is provided and may include a first-valve member 302, a
second-valve member 304, a valve seat member 306, an
intermediate-isolation seal 308, an upper seal 310, and a check
valve 312. The pressure-responsive valve 300 is movable in response
to the solenoid valve 130 being energized and de-energized to
facilitate movement of the piston 110 between the unloaded and
loaded positions.
[0057] The first-valve member 302 may include an upper-flange
portion 314, a longitudinally extending portion 316 extending
downward from the upper-flange portion 314, and a longitudinally
extending passage 318. The passage 318 may extend completely
through the first-valve member 302 and may include a flared check
valve seat 320.
[0058] The second-valve member 304 may be an annular disk disposed
around the longitudinally extending portion 316 of the first valve
member 302 and may be fixedly attached to the first-valve member
302. While the first- and second-valve members 302, 304 are
described and shown as separate components, the first- and
second-valve members 302, 304 could alternatively be integrally
formed. The first and second-valve members 302, 304 (collectively
referred to as the slave piston 302, 304) are slidable within the
body 102 between a first position (FIG. 8) and a second position
(FIG. 9) to prohibit and allow, respectively, fluid communication
between the control-pressure passage 124 and a vacuum port 322.
[0059] The intermediate-isolation seal 308 and the upper seal 310
may be fixedly retained in a seal-holder member 324, which in turn,
is fixed within the body 102. The intermediate-isolation seal 308
may be disposed around the longitudinally extending portion 316 of
the first-valve member 302 (i.e., below the upper-flange portion
314) and may include a generally U-shaped cross section. An
intermediate pressure cavity 326 may be formed between the U-Shaped
cross section of the intermediate-isolation seal 308 and the
upper-flange portion 314 of the first-valve member 302.
[0060] The upper seal 310 may be disposed around the upper-flange
portion 314 and may also include a generally U-shaped cross section
that forms an upper cavity 328 beneath the base of the solenoid
valve 130. The upper cavity 328 may be in fluid communication with
a pressure reservoir 330 formed in the body 102. The pressure
reservoir 330 may include a vent orifice 332 in fluid communication
with a suction-pressure port 334. The suction-pressure port 334 may
be in fluid communication with a source of suction gas such as, for
example, a suction inlet of a compressor. Feed drillings or
passageways 336, 338 may be formed in the body 102 and seal-holder
member 324, respectively, to facilitate fluid communication between
the suction-pressure port 334 and the intermediate pressure cavity
326 to continuously maintain the intermediate pressure cavity 326
at suction pressure. Suction pressure may be any pressure that is
less than discharge pressure and greater than a vacuum pressure of
the vacuum port 322. Vacuum pressure, for purposes of the present
disclosure, may be a pressure that is lower than suction pressure
and does not need to be a pure vacuum.
[0061] The valve seat member 306 may be fixed within the body 102
and may include a seat surface 340 and an annular passage 342. In
the first position (FIG. 8), the second-valve member 304 is in
contact with the seat surface 340, thereby forming a seal
therebetween and prohibiting communication between the
control-pressure passage 124 and the vacuum port 322. In the second
position (FIG. 9), the second-valve member 304 disengages the seat
surface 340 to allow fluid communication between the
control-pressure passage 124 and the vacuum port 322.
[0062] The check valve 312 may include a ball 344 in contact with
spring 346 and may extend through the annular passage 342 of the
valve seat member 306. The ball 344 may selectively engage the
check valve seat 320 of the first-valve member 302 to prohibit
communication of discharge gas between the solenoid valve 130 and
the control-pressure passage 124.
[0063] With continued reference to FIGS. 8 and 9, operation of the
pressure-responsive valve 300 will be described in detail. The
pressure-responsive valve 300 is selectively movable between a
first position (FIG. 8) and a second position (FIG. 9). The
pressure-responsive valve 300 may move into the first position in
response to the discharge gas being released by the solenoid valve
130. Specifically, as discharge gas flows from the solenoid valve
130 and applies a force to the top of the upper-flange portion 314
of the first-valve member 302, the valve members 302, 304 are moved
into a downward position shown in FIG. 8. Forcing the valve members
302, 304 into the downward position seals the second-valve member
304 against the seat surface 340 to prohibit fluid communication
between the vacuum port 322 and the control-pressure passage
124.
[0064] The discharge gas accumulates in the upper cavity 328 formed
by the upper seal 310 and in the discharge gas reservoir 330, where
it is allowed to bleed into the suction-pressure port 334 through
the vent orifice 332. The vent orifice 332 has a sufficiently small
diameter to allow the discharge gas reservoir to remain
substantially at discharge pressure while the solenoid valve 130 is
energized.
[0065] A portion of the discharge gas is allowed to flow through
the longitudinally extending passage 318 and urge the ball 344 of
the check valve 312 downward, thereby creating a path for the
discharge gas to flow through to the control-pressure passage 124
(FIG. 8). In this manner, the discharge gas is allowed to flow from
the solenoid valve 130 and into the chamber 120 to urge the piston
110 downward into the unloaded position.
[0066] To return the piston 110 to the upward (or loaded) position,
the solenoid valve 130 may be de-energized, thereby prohibiting the
flow of discharge gas therefrom. The discharge gas may continue to
bleed out of the discharge gas reservoir 330 through the vent
orifice 332 and into the suction-pressure port 334 until the
longitudinally extending passage 318, the upper cavity 328, and the
discharge gas reservoir 330 substantially reach suction pressure.
At this point, there is no longer a net downward force urging the
second-valve member 304 against the seat surface 340 of the valve
seat member 306. The spring 346 of the check valve 312 is
thereafter allowed to bias the ball 344 into sealed engagement with
check valve seat 320, thereby prohibiting fluid communication
between the control-pressure passage 124 and the longitudinally
extending passage 318.
[0067] As described above, the intermediate pressure cavity 326 is
continuously supplied with fluid at suction pressure (i.e.,
intermediate pressure), thereby creating a pressure differential
between the vacuum port 322 (at vacuum pressure) and the
intermediate pressure cavity 326 (at intermediate pressure). The
pressure differential between the intermediate pressure cavity 326
and the vacuum port 322 applies a force on valve members 302, 304
and urges the valve members 302, 304 upward. Sufficient upward
movement of the valve members 302, 304 allows fluid communication
between the chamber 120 and the vacuum port 322. Placing chamber
120 in fluid communication with the vacuum port 322 allows the
discharge gas occupying chamber 120 to evacuate through the vacuum
port 322. The evacuating discharge gas flowing from chamber 120 to
vacuum port 322 (FIG. 9) may assist the upward biasing force acting
on the valve members 302, 304 by the intermediate pressure cavity
326. The upward biasing force of the check valve 312 against the
check valve seat 320 may further assist the upward movement of the
valve members 302, 304 due to engagement between the ball 344 of
the check valve 302 and the valve seat 320 of the first-valve
member 302. Once the chamber 120 vents back to suction pressure,
the piston 110 is allowed to slide upward to the loaded position,
thereby increasing the capacity of the compressor.
[0068] In a condition where a compressor is started with discharge
and suction pressures being substantially balanced and the piston
110 is in the unloaded position, the pressure differential between
the intermediate pressure cavity 326 and the vacuum port 322
provides a net upward force on the valve members 302, 304, thereby
facilitating fluid communication between the chamber 120 and the
vacuum port 322. The vacuum pressure of the vacuum port 322 will
draw the piston 110 upward into the loaded position, even if the
pressure differential between the intermediate-pressure cavity 326
and the area upstream of 182 is insufficient to force the piston
110 upward into the loaded position. This facilitates moving the
piston 110 out of the unloaded position and into the loaded
position at a start-up condition where discharge and suction
pressures are substantially balanced.
[0069] Referring now to FIG. 10, another embodiment of a valve is
provided that includes a plurality of pistons 410 (shown raised and
lowered for illustration purposes only), each having a reed or
valve ring 440 slidably disposed within the lower end of the piston
410. Operation of the valve ring 440 is similar to the sealing
element 140 previously discussed in that discharge-pressure gas on
top of the valve ring 440 holds the valve ring 440 against the
valve seat 408 when the piston 410 is moved to the "down" position.
Discharge-pressure gas above seal C is confined by the outside and
inside diameter of the seal C. The valve ring 440 is loaded against
the valve seat 408 by the pressure in the piston 410 acting against
seal C, which has a high pressure above the seal C and a lower
pressure (system suction and/or a vacuum) under the seal C. When
the piston 410 is in the unloaded (downward) position and the valve
ring 440 is against the valve seat 408, suction gas has the
potential to leak between the upper surface of the valve ring 440
and the bottom surface of Seal C. The surface finish and design
characteristics of seal C must be appropriately selected to prevent
leakage at the interface between the upper surface of the valve
ring 440 and the bottom surface of Seal C.
[0070] The use of a porting plate 480 provides a means for routing
suction or discharge-pressure gas from the solenoid valve 430 to
the chambers 420 on top of single or multiple pistons 410. The port
on the solenoid valve 430 that controls the flow of gas to load or
unload the pistons 410 is referred to as the "common" port 470,
which communicates via control-pressure passage 424 to chambers
420. The solenoid valve 430 in this application may be a three-port
valve in communication with suction and discharge-pressure gas and
a common port 470 that is charged with suction or
discharge-pressure gas depending on the desired state of the piston
410.
[0071] Capacity may be regulated by opening and closing one or more
of the plurality of pistons 410 to control flow capacity. A
predetermined number of pistons 410 may be used, for example, to
block the flow of suction gas to a compressor, for example. The
percentage of capacity reduction is approximately equal to the
ratio of the number of "blocked" cylinders to the total number of
cylinders. Capacity reduction may be achieved by the various
disclosed valve mechanism features and methods of controlling the
valve mechanism. The valve's control of discharge-pressure gas and
suction-pressure gas may also be used in either a blocked suction
application or in a manner where capacity is modulated by
activating and de-activating the blocking pistons 410 in a
duty-cycle fashion. Using multiple pistons 410 to increase the
available flow area will result in increased full-load compressor
efficiency.
[0072] Furthermore, it is recognized that one or more pistons 110
forming a bank of valve cylinders may be modulated together or
independently, or one or more banks may not be modulated while
others are modulated. The plurality of banks may be controlled by a
single solenoid valve with a manifold, or each bank of valve
cylinders may be controlled by its own solenoid valve. The
modulation method may comprise duty-cycle modulation that for
example, provides an on-time that ranges from zero to 100% relative
to an off-time, where fluid flow may be blocked for a predetermined
off-time period. Additionally, the modulation method used may be
digital (duty-cycle modulation), conventional blocked suction, or a
combination thereof. The benefit of using a combination may be
economic. For example, a full range of capacity modulation in a
multi-bank compressor may be provided by using a lower-cost
conventional blocked suction in all but one bank, where the above
described digital modulation unloader piston configuration is
provided in the one remaining bank of cylinders.
[0073] FIG. 11 shows a portion of the compressor 10 that includes a
passage 502 in communication with a suction inlet of the compressor
10, and a chamber 504 in communication with a discharge pressure of
the compressor 10. The portion of the compressor 10 shown in FIG.
11 further includes the valve apparatus 100. The compressor 10
including the valve apparatus 100 has at least one unloader valve
(i.e., piston 110) for controllably modulating fluid flow to
passage 502 in communication with a suction inlet of the compressor
10.
[0074] As previously described and shown in FIG. 1, the valve
apparatus 100 has at least one valve opening 106 therein leading to
the passage 502 in communication with the suction inlet of the
compressor 10. A piston 110 is slidably disposed within a chamber
120 in the valve apparatus 100. The piston 110 is movable to block
the valve opening 106 to prohibit flow therethrough to passage 502.
The piston 110 and chamber 120 define a volume 122 therebetween,
where communication of a discharge-pressure gas to the volume 122
establishes a biasing force that urges the piston 110 away from the
valve opening 106.
[0075] The compressor 10 further includes a control-pressure
passage 124 in communication with the chamber 120, where the
control-pressure passage 124 communicates one of suction-pressure
gas or a discharge-pressure gas to the chamber 120. The
communication of discharge-pressure gas to the chamber 120 causes
the piston 110 to move to block the valve opening 106 to prohibit
flow therethrough. The communication of suction-pressure gas to the
chamber 120 and communication of discharge-pressure gas to the
volume 122 causes the piston 110 to move away from the valve
opening 106 to permit flow therethrough.
[0076] The compressor 10 may further include a valve member 126
proximate the control-pressure passage 124. As previously described
and shown in FIG. 5, the valve member 126 is movable between a
first position where the control-pressure passage 124 is prohibited
from communication with suction passage 502, and a second position
in which the control-pressure passage 124 is in communication with
the suction passage 502. Alternatively, the compressor 10 could
include the pressure-responsive valve 300, shown in FIGS. 8 and 9,
to selectively allow and prohibit fluid communication between the
control-pressure passage 124 and the suction passage 502.
[0077] The compressor 10 including the valve apparatus 100 may
further include a solenoid valve 130 for establishing or
prohibiting communication of discharge pressure to the valve member
126 (or the pressure-responsive valve 300). As previously described
and shown in FIGS. 5-10, communication of discharge-pressure gas to
the valve member 126 causes the valve member 126 to move to the
first position. In the first position, discharge-pressure gas is
communicated through the control-pressure passage 124 to the
chamber 120 to cause the piston 110 to move against the valve
opening 106 to block suction flow therethrough. Discontinuing or
prohibiting communication of discharge-pressure gas causes the
valve member 126 to move to the second position, in which
suction-pressure gas communicates with the chamber 120 to urge the
piston 110 away from the opening 106 and permit suction flow
therethrough.
[0078] As previously described and shown in FIG. 1, the combination
including the valve apparatus 100 may further include a valve
element 140 slidably disposed within the piston 110 and configured
to engage a valve seat 108 adjacent the valve opening 106. When the
valve element 140 engages the valve seat 108, the valve element 140
is configured to remain stationary while the piston 110 slides
relative to the stationary valve element 140 to seat against the
valve opening 106. In this manner, the piston 110 does not impact
against the valve element 140, thereby preventing damage to the
valve element 140.
[0079] The one or more pistons 110 in the above disclosed
compressor combination may be controlled by a solenoid valve
assembly, for example, that directs either discharge pressure or
suction pressure to the top of each piston 110. The solenoid or the
pressure-responsive valve may be configured to vent the pressure
above the valve member 126 (or slave piston 160 or 302, 304) to a
low pressure source, such as a chamber at suction pressure or
vacuum pressure on the closed side of the unloader piston. A single
solenoid valve 130 may be capable of operating multiple unloader
pistons 110 of the valve apparatus 100 simultaneously, through a
combination of drillings and gas flow passages.
[0080] It should be noted that the compressor 10 and valve
apparatus 100 may alternatively be operated or controlled by
communication of a control pressure a separate external flow
control device (FIGS. 8 and 9). Additionally, the compressor 10
including the valve apparatus 100 may comprise combinations of one
or more of the above components or features, such as the solenoid
assembly 130, which may be separate from or integral with the
compressor 10.
* * * * *