Note: Descriptions are shown in the official language in which they were submitted.
CA 02881255 2015-02-05
258255
COMPRESSOR WITH MAGNETICALLY
ACTUATED VALVE ASSEMBLY
BACKGROUND OF THE INVENTION
[0001] The invention relates generally to compressors with magnetically
actuated
valve assembly. More particularly, the invention relates to compressors for
refrigerators
with magnetically actuated valve assembly.
[0002] Valves having different operating principles may be used in
compressors.
Reed valve is an example of a valve assembly typically used in small
compressors for air
condition systems or refrigerators. A typical reed valve includes a reed valve
plate
(which is usually a thin metal sheet) that is clamped on one side, and is free
on the other
side. Due to a gas pressure difference differential between inlet and outlet
side of the
reed valve, it bends upwards to release the overpressure.
[0003] Valve dynamics may govern part of the pressure losses for a
compressor
eventually determining the efficiency, usually determined by the effective
efficiency ratio
(EER). Late closure or early opening of the valve may cause a deviation from
the ideal
compression-expansion cycle, which may lead to extra work input and lower EER.
Further, due to a spring interaction of the reed valve plate and the gas, the
valve plate
may oscillate during the opening and closing of the valve, which in turn could
lead to
increased collision of the valve reed with the valve plate or valve stop.
These oscillations
may cause noise, material fatigue (leading to reduced valve life), and
increased flow
losses. Furthermore, part load operation may only be realized in a typical
compressor, by
using a bypass or reduction of compressor motor speed.
[0004] Thus, there is a need for improved valve assembly configurations
for
compressors. Further, there is a need for improved valve assembly
configurations for
compressors used in refrigerators.
1
CA 02881255 2015-02-05
258255
BRIEF DESCRIPTION OF THE INVENTION
[0005] One embodiment is directed to a compressor including a housing, a
cylinder disposed in the housing, and a piston disposed in the housing. The
cylinder and
the piston define a compression chamber, a discharge chamber, and a suction
chamber.
The compressor further includes at least one valve assembly including a valve
member
disposed in the housing, wherein the compression chamber is in fluid
communication
with the discharge chamber or the suction chamber via the valve assembly. The
compressor further includes at least one magnetic valve actuation element
disposed in the
housing, wherein at least one of the magnetic valve actuation element and the
valve
assembly includes an electromagnet, the electromagnet configured to
magnetically
actuate the valve member in response to an actuation signal.
[0006] Another embodiment of the invention is directed to a compressor
including a housing, a cylinder disposed in the housing, and a piston disposed
in the
housing. The cylinder and the piston define a compression chamber, a discharge
chamber, and a suction chamber. The compressor includes at least one valve
assembly
including a valve member disposed in the housing, wherein the compression
chamber is
in fluid communication with the discharge chamber or the suction chamber via
the valve
assembly. The valve assembly includes a ferromagnetic material disposed on a
surface
of the valve member, a permanent magnet disposed on a surface of the valve
member, or
combinations thereof. The compressor further includes at least one
electromagnet
disposed in the housing such that the electromagnet is configured to actuate
the valve
member in response to an actuation signal.
[0007] Another embodiment of the invention is directed to a compressor
including a housing, a cylinder disposed in the housing, and a piston disposed
in the
housing. The piston further includes at least one magnetic element. The
cylinder and the
piston define a compression chamber, a discharge chamber, and a suction
chamber. The
compressor includes at least one valve assembly including a valve member
disposed in
the housing, wherein the compression chamber is in fluid communication with
the
2
CA 02881255 2015-02-05
258255
discharge chamber or the suction chamber via the valve assembly, wherein the
valve
assembly includes an electromagnet configured to actuate the valve member in
response
to an actuation signal.
DRAWINGS
[0008] These and other features, aspects, and advantages of the present
invention
will become better understood when the following detailed description is read
with
reference to the accompanying drawings, in which like characters represent
like parts
throughout the drawings, wherein:
[0009] FIG. 1 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0010] FIG. 2 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0011] FIG. 3 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0012] FIG. 4 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0013] FIG. 5 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0014] FIG. 6 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0015] FIG. 7 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0016] FIG. 8 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
3
CA 02881255 2015-02-05
258255
[0017] FIG. 9 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0018] FIG. 10 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0019] FIG. 11 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0020] FIG. 12 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0021] FIG. 13 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0022] FIG. 14 illustrates a cross-section view of a compressor, according
to an
embodiment of the invention;
[0023] FIG. 15 illustrates a refrigerator including the compressor,
according to an
embodiment of the invention.
[0024] FIG. 16 shows the flux density in reed valve and solenoid from
magnetic
flux simulation using finite elements;
[0025] FIG. 17 shows a plot of magnetic force versus distance between reed
valve
and electromagnet; and
[0026] FIG. 18 shows the plot of pressure versus volume for one
compression
cycle.
DETAILED DESCRIPTION
[0027] Approximating language, as used herein throughout the specification
and
claims, may be applied to modify any quantitative representation that could
permissibly
4
CA 02881255 2015-02-05
258255
vary without resulting in a change in the basic function to which it is
related.
Accordingly, a value modified by a term or terms, such as "about", and
"substantially" is
not to be limited to the precise value specified. In some instances, the
approximating
language may correspond to the precision of an instrument for measuring the
value. Here
and throughout the specification and claims, range limitations may be combined
and/or
interchanged, such ranges are identified and include all the sub-ranges
contained therein
unless context or language indicates otherwise.
[0028] In the following specification and the claims, the singular forms
"a", "an"
and 'the" include plural referents unless the context clearly dictates
otherwise. As used
herein, the term "or" is not meant to be exclusive and refers to at least one
of the
referenced components being present and includes instances in which a
combination of
the referenced components may be present, unless the context clearly dictates
otherwise.
[0029] As used herein, the terms "may" and "may be" indicate a possibility
of an
occurrence within a set of circumstances; a possession of a specified
property,
characteristic or function; and/or qualify another verb by expressing one or
more of an
ability, capability, or possibility associated with the qualified verb.
Accordingly, usage
of "may" and "may be" indicates that a modified term is apparently
appropriate, capable,
or suitable for an indicated capacity, function, or usage, while taking into
account that in
some circumstances, the modified term may sometimes not be appropriate,
capable, or
suitable.
[0030] In some embodiments, a compressor is presented. The term
"compressor"
as used herein refers to a mechanical device that increases the pressure of a
fluid by
reducing its volume. In some embodiments, the compressor as described herein
may be
configured to operate an air conditioning system, a refrigeration system, a
cooling
system, or combinations thereof. In certain embodiments, the compressor as
described
herein is configured to operate a refrigerator, and the fluid worked upon by
the
compressor is a refrigerant.
CA 02881255 2015-02-05
258255
[0031] The compressor may be further classified as a reciprocating
compressor, a
linear compressor, rotary compressor, a scroll compressor, and the like,
according to the
mechanism used for compressing the fluid (e.g., a refrigerant). Some
embodiments of the
invention present a reciprocating compressor having the magnetically actuated
valve
assembly described herein. Some other embodiments of the present invention
present a
linear compressor having the magnetically actuated valve assembly described
herein.
[0032] Figures 1-10 illustrate representative cross-sectional views of the
compressor 100, in accordance with some embodiments of the invention. As
indicated in
Figures 1-10, the compressor 100 includes a housing 110. The compressor 100
further
includes a cylinder 120 and a piston 130 disposed in the housing 110. As shown
in
Figures 1-10, the cylinder 120 and the piston 130 define a compression chamber
111, a
discharge chamber 112, and a suction chamber 113.
[0033] As mentioned earlier, the compressor 100 in accordance with some
embodiments of the invention may be a reciprocating compressor or a linear
compressor.
Figures 1-6 illustrate embodiments for a reciprocating compressor 100, whereas
Figures
7-10 illustrate embodiments for a linear compressor 100. In a reciprocating
compressor
100, as shown in Fig. 1, the piston 130 and the cylinder 120 define the
compression
chamber 111, the discharge chamber 112, and the suction chamber 113, such that
the
fluid (e.g., the refrigerant) flows in (shown by arrows) from the suction
chamber 113 to
the compression chamber 111, where it is compressed by the piston 130, and
flows out
from the compression chamber 111 to the discharge chamber 112 (shown by
arrows).
Similarly, in a linear compressor 100, the piston 130 and the cylinder 120
define the
compression chamber 111, the discharge chamber 112, and the suction chamber
113, as
shown in Fig. 7. However, in one example embodiment of a linear compressor
100, the
suction chamber 113 is present in the piston 130, and the fluid (e.g., the
refrigerant) flows
in (shown by arrows) from the suction chamber 113 (present in the piston 130)
to the
compression chamber 111, where it is compressed by the piston 130, and flows
out from
the compression chamber 111 to the discharge chamber 112 (shown by arrows). In
some
6
CA 02881255 2015-02-05
258255
embodiment, a configuration of the suction chamber in the compressor may be
similar to
the reciprocating compressor.
[0034] With continued reference to Figures 1 and 7, the compressor 100
further
includes at least one suction port 114 and a discharge port 115. The suction
port 114
allows for the fluid to enter the compression chamber 111 from the suction
chamber 113,
and the discharge port 115 allows for the exit of the fluid from the
compression chamber
111 to the discharge chamber 112. Typically, both suction port 114 and the
discharge
port 115 are opened and closed using valve assemblies (such, as reed valves)
that are
actuated by the pressure differential across the two chambers. However, as
alluded to
previously, conventional valve assemblies may not open or close in time, thus
resulting in
efficiency loss. Further, valve plate may oscillate (or flutter) during the
opening and
closing of the valve, which in turn could lead to noise, material fatigue
(leading to
reduced valve life), and increased losses.
[0035] Embodiments of the invention described herein address the noted
shortcomings of the state of the art. According to some embodiments of the
invention,
the compressor 100 further includes at least one valve assembly 140 disposed
in the
housing 110, as indicated in Figures 1-10. The compression chamber 111 is in
fluid
communication with the suction chamber 113 or the discharge chamber 112 via
the valve
assembly 140. The term "fluid communication" as used herein means that a fluid
can
flow from the compression chamber 111 to the discharge chamber 112 or the
suction
chamber 113, via the valve assembly 140. Accordingly, the valve assembly 140
may be
configured to open/close the suction port 114 (Figures 2, 3, 6, 9, and 10) or
the discharge
port 115 (Figures 1, 4, 5, 7, and 8). The valve assembly 140 configured to
open/close the
suction port may be sometimes referred to as the "suction valve" in the text.
Similarly,
the valve assembly 140 configured to open/close the discharge port may be
sometimes
referred to as the "discharge valve" in the text.
[0036] It should be noted that Figures 1-10, for the sake of
representation and
brevity, indicate only a single valve assembly (on the discharge or the
suction side) that is
7
CA 02881255 2015-02-05
258255
magnetically actuated. However, as will be apparent to one of ordinary skill
in the art,
the compressor 100 in operation would include at least one additional valve
assembly
(not shown), which may or may not be magnetically actuated, in accordance with
embodiments of the invention. Figures 12 and 14 illustrate embodiments of the
invention
(described in detail later) in which both the suction and the discharge valve
assemblies
are magnetically actuated.
[0037] Referring again to Figures 1-10, the valve assembly 140 includes a
valve
member 142. In some embodiments, the valve assembly 140 may be a reed valve,
and
the valve member 142 may be a reed plate or a reed. The valve member 142 may
include
any suitable material and in some embodiments may be in the form of a thin
plate.
[0038] With continued reference to Figures 1-10, the compressor 100
further
includes at least one magnetic valve actuation element 150 disposed in the
housing 110.
The term "magnetic valve actuation element" as used herein refers to an
element
including a ferromagnetic material or a magnet. The magnet may further include
an
electromagnet or a permanent magnet. A suitable configuration of the magnetic
valve
actuation element 150 may be chosen depending, in part, on one or both of the
location of
the magnetic valve actuation element 150 and the valve assembly 140 type.
[0039] In some embodiments, the magnetic valve actuation element 150 is
disposed in the housing 110 such that the magnetic valve actuation element 150
is
proximate to the valve assembly 140 during operation of the compressor 100, in
particular during the compression cycle when the valve assembly 140 needs to
be
actuated. In* some embodiments, as shown in Figures 1-3, 7 and 9, the magnetic
valve
actuation element 150 is disposed in the suction chamber 113 or the discharge
chamber
112. In some such embodiments, the magnetic valve actuation element 150 may be
attached to one more of the interior surface of the housing 110, the interior
surface of the
cylinder 120, and the cylinder head. In some other embodiments, as shown in
Figures 4-
6, 8 and 10, the piston 130 may include the magnetic valve actuation element
150, and
8
CA 02881255 2015-02-05
258255
the magnetic valve actuation element 150 may be disposed on a surface of the
piston
head or embedded inside the piston itself.
[0040] As mentioned previously, embodiments of the invention present
magnetically actuated valve assemblies for compressor. Accordingly, at least
one of the
magnetic valve actuation element 150 and the valve assembly 140 includes an
electromagnet; the electromagnet is configured to magnetically actuate the
valve member
142 in response to an actuation signal. A suitable electromagnet may include a
solenoid
core and a coil of a conductive material (e.g., copper). Non-limiting examples
of suitable
solenoid configurations may include E-shaped, round shaped, or rectangular
shaped core.
In certain embodiments, a suitable solenoid configuration may include an E-
shaped core.
[0041] The term "magnetically actuate" as used herein means that in
response to
an actuation signal a magnetic force is initiated or terminated between the
magnetic valve
actuation element 150 and the valve assembly 140, such the valve member 142 is
actuated. The terms "actuated" and "actuation" as used herein include
initiating or
assisting in opening/closing of the valve member 142. Further, the term
"actuated" also
includes keeping the valve member 142 open/closed for the desired period of
time. As
mentioned earlier, a valve member 142 is actuated in a typical compressor
based on the
pressure differential across the clambers. As will be apparent to one of
ordinary skill in
the art, in the embodiments described herein, the valve member 142 is
magnetically
actuated in conjunction with the pressure differential across the chambers.
[0042] In some embodiments, the compressor 100 may further include one or
more controllers and sensors (not shown). The sensor may be configured to
determine
one or more of the location of the valve member 142, the location of the
piston 130, the
gas pressure in the compression chamber 111, the gas pressure in the discharge
chamber
112, and the gas pressure in the suction chamber 113. The sensor may be
further
configured to send an actuation signal to the controller such that an
intensity and/or
direction of the current applied to the electromagnet is altered, thereby
actuating the
valve member 142.
9
CA 02881255 2015-02-05
258255
[0043] According
to one embodiment of the invention, the magnetic valve
actuation element 150 may be disrmsed in the suction chamber 113 or the
discharge
chamber 112, as shown in Figures 1-3, 7 and 9. In some such embodiments, the
magnetic valve actuation element 150 includes an electromagnet, as shown in
Figures 1-
3, 7 and 9. Further, in such embodiments, wherein the magnetic valve actuation
element
150 includes an electromagnet, the valve assembly 140 includes a ferromagnetic
material
144 disposed on a surface of the valve member 142, a permanent magnet 144
disposed on
a surface of the valve member 142, or another electromagnet.
[0044] In certain
embodiments, the valve assembly 140 includes a ferromagnetic
material 144 disposed on a surface of the valve member 142, a permanent magnet
144
disposed on a surface of the valve member 142, or combinations thereof. This
is in
contrast to a valve assembly including a valve plate (or a reed) that is
itself
ferromagnetic. In such instances, the thin valve plate (or reed) may quickly
get
magnetically saturated and may not generate sufficient magnetic force to
actuate the reed.
Thicker valve plate (or reed) on the other hand may not have the desired
resilience or
flexibility to bend in response to the gas pressure across the chamber.
Some
embodiments of the invention address the noted shortcomings of the art by
including an
additional layer of a ferromagnetic material or a permanent magnet 144
disposed on a
surface of the valve member 142, as indicated in Figures 1-3, 7, and 9.
[0045] In some
embodiments, the valve member 142 has a thickness in a range
from about 0.05 millimeters to about 0.35 millimeters. The
thickness of the
ferromagnetic material or permanent magnet may be chosen to achieve the
desired
magnetic flux without significantly effective the resilience of the valve
member 142. A
suitable thickness of the ferromagnetic material or the permanent magnet may
be in a
range from about 0.1 millimeters to about 0.5 millimeters, in some
embodiments. Non-
limiting examples of suitable ferromagnetic materials may include iron, iron
alloys,
ferrite, nickel, or combinations thereof. The ferromagnetic material or the
permanent
magnet 144 may be disposed on a portion of the surface of the valve member 142
or may
CA 02881255 2015-02-05
258255
substantially cover the surface of the valve member 142. Further, in some
embodiments,
it may be desirable that the ferromagnetic material or the permanent magnet is
disposed
on a surface of the valve member 142 that is facing the magnetic valve
actuation element
150.
[0046] In some
embodiments, both the magnetic valve actuation element 150 and
the valve assembly 140 may include electromagnets (not shown in Figures). In
such
instances, one or both of the magnetic valve actuation element 150 and the
valve
assembly 140 may be configured to receive an actuation signal to actuate the
valve
member 142. In some embodiments, an electromagnet may be arranged around the
valve
member 142, or alternatively, in some other embodiments, the valve member 142
itself
may be an electromagnet.
[0047] In some
embodiments, the magnetic valve actuation element 150 may be
configured to receive an activation signal when the valve member 142 is at a
determined
position relative to the magnetic valve actuation element 150, thereby
generating an
attractive or a repulsive magnetic force such that the valve assembly 140 is
opened.
Referring again to Figures 1, 3 and 7, in order to open the discharge or
suction valve
assembly 140, an attractive magnetic force may be generated between the
magnetic valve
actuation element 150 and the valve assembly 140, such that the opening of the
valve
assembly 140 is assisted along with the pressure differential generated across
the
chambers. Similarly, in Figures 2 and 9, in order to open the suction valve
assembly 140,
a repulsive magnetic force may be generated between the magnetic valve
actuation
element 150 and the valve assembly 140.
[0048] In some
other embodiments, the opening of the valve assembly 140 may
be primarily effected using the pressure differential across the chambers and
the magnetic
valve actuation element 150 may be employed to keep the valve assembly 140
open such
that the fluttering of the valve assembly 140 is minimized. In some such
embodiments,
the magnetic valve actuation element 150 may be configured to receive an
activation
signal when the valve member 140 is in contact with the magnetic valve
actuation
11
=
CA 02881255 2015-02-05
258255
element 140, thereby generating an attractive magnetic force such that the
valve assembly
140 is kept open.
[0049] In some embodiments, the magnetic valve actuation element 150 may
be
configured to receive an activation signal when a gas pressure in the
compression
chamber reaches a determined value, thereby generating an attractive magnetic
force,
generating a repulsive magnetic force, or deactivating the magnetic force,
such that the
valve assembly 140 is closed. Referring again to Figures 1, 3 and 7, in some
embodiments, in order to close the discharge or suction valve assembly 140, a
repulsive
magnetic force may be generated between the magnetic valve actuation element
150 and
the valve assembly 140, such that the closing of the valve assembly 140 is
assisted along
with the pressure differential generated across the chambers. Similarly, in
Figures 2 and
9, in order to close the suction valve assembly 140, an attractive magnetic
force may be
generated between the magnetic valve actuation element 150 and the valve
assembly 140.
[0050] In some other embodiments, in order to close the discharge or
suction
valve assembly 140, the electrical current to the magnetic valve actuation
element 150
may be turned off to deactivate the magnetic force between the magnetic valve
actuation
element 150 and the valve assembly 140, such that the closing of the valve
assembly 140
is assisted, along with the spring force.
[0051] Thus by way of example, the valve member (e.g., reed) 142 in Fig. 1
may
open because of overpressure at the compression chamber 111 side. As the valve
member 142 gets closer to or is in contact with the magnetic valve actuation
element 150,
an actuation signal may be sent by the sensor to a controller, such that the
magnetic valve
actuation element (e.g., solenoid) 150 may get powered to generate an
attractive force,
and the valve assembly 140 is kept open to allow the fluid to pass through it.
Once, the
gas pressure in the compression chamber 111 and the discharge chamber 112 is
substantially the same, a sensor may send a deactivation signal, such that the
magnetic
valve actuation element 150 is unpowered and the valve member 142 is closed
because of
the spring force.
12
CA 02881255 2015-02-05
258255
[0052] According
to some embodiments of the invention, the magnetic circuit of
the electromagnet (e.g., solenoid) may be closed when the valve member 142 is
at its
maximum stroke position, which results in strong magnetic forces and the valve
member
142 is fixed in an open position. This "clamping" or "fixing" of the valve
member 142 to
the electromagnet (e.g., solenoid) may avoid oscillations during the opening
phase.
Further, using this configuration, the valve member 142 closing time may be
shifted to a
later point (by generating the appropriate repulsive or attractive magnetic
force), thus
enabling part load operation of the compressor.
[0053] In some
other embodiments, the valve assembly 140 may include the
electromagnet configured to actuate the valve member 142, and the magnetic
valve
actuation element 150 may include a ferromagnetic material, a permanent
magnet, or
another electromagnet. In such embodiments, when the valve member 142 is at a
determined position relative to the magnetic valve actuation element 150, a
sensor may
send an activation signal to the controller, thereby generating an attractive
magnetic force
such that the valve assembly is opened. Further, in such embodiments, when a
gas
pressure in the compression chamber 111 reaches a determined value, a sensor
may send
a deactivation signal to the controller, thereby generating a repulsive
magnetic force, or
deactivating the magnetic force, such that the valve assembly 140 is closed.
[0054] According
to another embodiment of the invention, the piston 130
includes the magnetic valve actuation element 150, as shown in Figures 4-6, 8,
and 10.
The magnetic valve actuation element 150 in such embodiments may be disposed
on a
surface of the piston head (Figures 5 and 6) or disposed inside the piston
itself (Figures 4,
8 and 10). In some other embodiments, the magnetic valve actuation element 150
may be
attached or fixed to the piston 130 (embodiment not shown).
[0055] In some
such embodiments, the valve assembly 140 includes an
electromagnet and the magnetic valve actuation element 150 includes a
permanent
magnet or a ferromagnetic material, as shown in Figures 4-6, 8 and 10. As
noted earlier,
the electromagnet is configured to actuate the valve assembly 140 in response
to an
13
CA 02881255 2015-02-05
258255
actuation signal. In some embodiments, an electromagnet may be arranged around
the
valve member 142, or alternatively, in some other embodiments, the valve
member 142
itself may be an electromagnet.
[0056] In some embodiments, the electromagnet in the valve assembly 140
may
be configured to actuate the valve member 142 when the piston 130 is at a
determined
position relative to valve assembly 140, thereby generating an attractive or a
repulsive
magnetic force such that the valve assembly 140 is opened. Referring again to
Figures 4-
5, 8 and 10 in order to open the discharge or suction valve assembly 140, a
repulsive
magnetic force may be generated between the magnetic valve actuation element
150 and
the valve assembly 140, such that the opening of the valve assembly 140 is
assisted along
with the pressure differential generated across the chambers. Similarly, in
Fig. 6, in order
to open the suction valve assembly 140, an attractive force may be generated
between the
magnetic valve actuation element 150 and the valve assembly 140.
[0057] In some embodiments, the electromagnet in the valve assembly 140
may
be configured to actuate the valve member 142 when the piston 130 is at a
determined
position relative to valve assembly 140, thereby generating an attractive or a
repulsive
magnetic force such that the valve assembly 140 is closed. Referring again to
Figures 4-
5, 8 and 10 in order to close the discharge or suction valve assembly 140, an
attractive
magnetic force may be generated between the magnetic valve actuation element
150 and
the valve assembly 140, such that the closing of the valve assembly 140 is
assisted along
with the pressure differential generated across the chambers. Similarly, in
Fig. 6, in order
to close the suction valve assembly 140, a repulsive force may be generated
between the
magnetic valve actuation element 150 and the valve assembly 140.
[0058] In some other embodiments, in order to close the discharge or
suction
valve assembly 140, the electrical current to the electromagnet in the valve
assembly 140
may be turned off to deactivate the magnetic force between the magnetic valve
actuation
element 150 and the valve assembly 140, such that the closing of the valve
assembly 140
is assisted, along with the spring force.
14
CA 02881255 2015-02-05
258255
[0059] Thus, by way of example, and with reference to the discharge valve
assembly 140 in Fig. 5, a switching of the magnetic force between the magnetic
valve
actuation element 150 and the valve assembly 140 is described to magnetically
actuate
the valve assembly 140. In Fig. 5, as the piston gets closer to the valve
assembly 140
(that is approaches top dead center (TDC)), in response to a sensor, an
activation signal
may be sent to a controller, such that a repulsive magnetic force is generated
between the
magnetic valve actuation element 150 and the valve assembly 140. This
repulsive
magnetic force along with the pressure differential between the compression
chamber
111 and the discharge chamber 112 may assist in rapid opening of the valve. At
a
particular distance of the piston 130, in response to a sensor, a deactivation
signal may be
sent to a controller, such that the magnetic force switches to an attractive
force (e.g., by
changing the current direction to the electromagnet), and counteracts the
pressure
differential, thereby keeping the valve open at a fixed position. As the
distance between
the piston 130 and the valve assembly 140 goes on decreasing, this magnetic
force
increases and enables closure of the valve assembly 140 when the piston 130
reaches the
TDC.
[0060] Similarly, with reference to the suction valve assembly 140 as
shown in
Fig. 6, as the piston move away from the valve assembly 140, in response to a
sensor, an
activation signal may be sent to a controller, such that an attractive
magnetic force is
generated between the magnetic valve actuation element 150 and the valve
assembly 140.
This attractive magnetic force along with the pressure differential between
the
compression chamber 111 and the suction chamber 113 may assist in rapid
opening of
the valve. As the piston 130 moves closer to the bottom dead center (BDC), in
response
to a sensor, a deactivation signal may be sent to a controller, such that the
magnetic force
switches to a repulsive force (e.g., by changing the current direction to the
electromagnet), and counteracts the pressure differential, thereby closing the
valve.
Thus, by using magnetic valve actuation elements in the piston 130, the valves
may
open/close at desired crank angle locations (e.g., suction valve at bottom
dead center and
discharge valve at top dead center). Further, the presence of magnetic force
may
CA 02881255 2015-02-05
258255
decrease the maximum lift (thereby decreasing the collision velocity), and
flutter
frequency of the valve members.
[0061] As alluded to previously, the compressor 100 may include a
plurality of
valve assemblies, a plurality of magnetic valve actuation elements, or both.
According to
one embodiment of the invention, a compressor 100 includes a plurality of
magnetic
valve actuation elements is presented, as shown in Figures 11 and 13. Fig. 11
illustrates a
cross-sectional view of a reciprocating compressor, while Fig. 13 illustrates
a cross-
sectional view of a linear compressor. In Figures 11 and 13, the compressor
100 includes
a first magnetic actuating element 150 disposed in the discharge chamber 112
and a
second magnetic actuating element 170, wherein the piston 130 includes the
second
magnetic actuating element 170. The compressor 100 further includes the valve
assembly 140, such that at least one of the first magnetic actuating element
150, the
second magnetic actuating element 170, and the valve assembly 140 includes the
electromagnet. In the example embodiments illustrated in Figures 11 and 13,
the valve
member 142 includes the electromagnet. In such embodiments, for example, to
effect
opening of the valve, an attractive magnetic force may be generated between
the valve
member 142 and the first magnetic valve actuation element 150, and a repulsive
magnetic
force may be generated between the valve member 142 and the second magnetic
valve
actuation element 170. To close the valve, the magnetic force polarities may
be reversed.
[0062] In such instances, the actuation of the valve member 142 may be
effected
by the combined effect of both the magnetic valve actuation elements 150/170,
thereby
resulting in faster opening/closing of the valves and lesser number of
oscillations. The
increasing strength of the magnetic force (both repulsive and attractive) as
the piston 130
moves closer or further, may result in a faster response of the valve. Thus,
by optimizing
the magnetic force strength between the valve and the two magnetic valve
actuation
elements and the timing of magnetic force switching, a compressor
configuration having
an improved net EER and increased valve life may be obtained.
16
CA 02881255 2015-02-05
258255
[0063] According
to one embodiment of the invention, a compressor 100 include a
plurality of valve assemblies and magnetic valve actuation elements is
presented, as
shown in Figures 12 and 14. Fig. 12 illustrates a cross-sectional view of a
reciprocating
compressor while Fig. 14 illustrates a cross-sectional view of a linear
compressor. In
Figures 12 and 14, the compressor 100 includes a first valve assembly 140
including a
first valve member 142 and a second valve assembly 160 including a second
valve
member 162. As shown in Figures 12 and 14, the compression chamber 111 is in
fluid
communication with the discharge chamber 112 via the first valve assembly 140,
and the
compression chamber 111 is in fluid communication with the suction chamber 113
via
the second valve assembly 160. The compressor 100 further includes a first
magnetic
valve actuation element 150 and a second magnetic valve actuation element 170.
At least
one of the first magnetic valve actuation element 150 and the first valve
assembly 140
includes a first electromagnet, the first electromagnet configured to
magnetically actuate
the first valve member 142 in response to a first actuation signal, as shown
in Figures 12
and 14. Further, at least one of the second magnetic valve actuation element
170 and the
second valve assembly 160 includes a second electromagnet, the second
electromagnet
configured to magnetically actuate the second valve member 162 in response to
a second
actuation signal. In the example embodiments illustrated in Figures 12 and 14,
the
second valve member 162 includes the electromagnet. Further, the first valve
assembly
140 includes a ferromagnetic material or a permanent magnet 144 disposed on a
surface
of the valve member 142, and the first magnetic valve actuation element 150
includes the
electromagnet. In such instances, the actuation of the both the discharge and
suction
valves may be effected by magnetic actuation, thereby resulting faster
opening/closing of
the valves and lesser number of oscillations.
[0064] In some
embodiments, a refrigerator unit (e.g., a household refrigerator)
including a compressor as described herein is presented. In a refrigerator, a
compressor
is used to compress a refrigerant. In a household refrigerator, as the
refrigerant passes
through one or more evaporators (not shown), the refrigerant absorbs heat from
one or
more refrigerator compartments (not shown) and hence produces a cooling
effect. In the
17
CA 02881255 2015-02-05
258255
evaporator, the refrigerant undergoes an expansion and the expanded
refrigerant is
compressed in the compressor. Fig. 15 shows a refrigerator unit 200 including
one
example compressor 100 configuration. A suitable compressor configuration as
described herein may be used in the refrigerator 200.
[0065] The compressor configurations as described herein, in accordance
with the
embodiments of the invention, may provide for one or more of (i) late closure
of
discharge valve and/or suction valve, (ii) less number of oscillation or
flutter frequency,
(iii) faster valve response time, (iv) improved valve life, (v) improvement in
EER, and
(vi) part load operation.
EXPERIMENTAL
Example 1
[0066] Simulation tests were conducted to calculate the magnetic force for
a
particular reed thickness. Fig. 16 shows the flux density in reed valve (reed
thickness
0.3 millimeters) and solenoid from magnetic flux simulation using finite
elements. As
shown in Fig. 16, the thin reed plate is a bottleneck for flux lines. Thicker
plates may
show higher magnetic forces but may affect the valve dynamics. Fig. 17 shows
the
magnetic force generated as function of distance between reed valve and
electromagnet.
In the example shown in Fig. 17, a maximum force of 1.33N is generated at a
thickness
of 0.5 millimeters. Accordingly, in this example, an additional ferromagnetic
material
(of approximately ¨0.2 mm thickness) may be disposed on the reed to generate
the
desired magnetic flux. Fig. 18 shows the pressure versus volume for one
compression
cycle. At least a portion of the losses (shown by hashed region) may be
reduced with the
magnetically actuated valve, in accordance with some embodiments of the
invention.
[0067] The present invention has been described in terms of some specific
embodiments. They are intended for illustration only, and should not be
construed as
being limiting in any way. Thus, it should be understood that modifications
can be made
thereto, which are within the scope of the invention and the appended claims.
18
CA 02881255 2015-02-05
258255
Furthermore, all of the patents, patent applications, articles, and texts
which are
mentioned above are incorporated herein by reference.
19
