U.S. patent application number 12/408081 was filed with the patent office on 2010-04-29 for system and method for cooling air conditioning system electronics.
This patent application is currently assigned to Enviro Systems, Inc.. Invention is credited to Theodore L. Belshe, Craig A. Froelich, Stephen D. Rigney.
Application Number | 20100101242 12/408081 |
Document ID | / |
Family ID | 42116161 |
Filed Date | 2010-04-29 |
United States Patent
Application |
20100101242 |
Kind Code |
A1 |
Froelich; Craig A. ; et
al. |
April 29, 2010 |
SYSTEM AND METHOD FOR COOLING AIR CONDITIONING SYSTEM
ELECTRONICS
Abstract
A system, method and apparatus for cooling the electronic
components that regulate power and commutation of a refrigerant
compressor motor in an air conditioning system. The electronic
components are juxtaposed upon a heat sink provided with a
refrigerant passageway. The heat sink is fluidly disposed in the
refrigeration line between the evaporator assembly and compressor
such that refrigerant returning from the evaporator assembly to the
compressor of the air conditioning system travels directly to the
heat sink and through the refrigerant passageway before reaching
the compressor.
Inventors: |
Froelich; Craig A.;
(Seminole, OK) ; Belshe; Theodore L.; (Tecumseh,
OK) ; Rigney; Stephen D.; (Shawnee, OK) |
Correspondence
Address: |
GALLOP, JOHNSON & NEUMAN, L.C.
101 S. HANLEY, SUITE 1600
ST. LOUIS
MO
63105
US
|
Assignee: |
Enviro Systems, Inc.
Seminole
OK
|
Family ID: |
42116161 |
Appl. No.: |
12/408081 |
Filed: |
March 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61197212 |
Oct 24, 2008 |
|
|
|
Current U.S.
Class: |
62/56 ;
62/505 |
Current CPC
Class: |
B64D 2013/0674 20130101;
F25B 31/006 20130101; B64D 13/08 20130101; B64D 2013/0614
20130101 |
Class at
Publication: |
62/56 ;
62/505 |
International
Class: |
F25D 3/00 20060101
F25D003/00; F25B 31/00 20060101 F25B031/00 |
Claims
1. A system for cooling the power and commutation electronics used
to control the motor of a compressor in an air conditioning
refrigeration system, the system comprising: a refrigeration system
including a compressor and an evaporator assembly connected by a
refrigerant line; a motor control unit electrically connected to
the compressor motor, the motor control unit containing electronic
components that control the compressor motor; the electronic
components being mounted in heat transfer relation to a heat sink;
the heat sink including a refrigerant passageway for the passage of
refrigerant there through and being fluidly disposed in the
refrigeration line between the evaporator assembly and compressor
such that refrigerant returning from the evaporator assembly to the
compressor of the air conditioning system travels directly to the
heat sink and through the refrigerant passageway before reaching
the compressor.
2. The system of claim 1 wherein the refrigerant returning from the
refrigerant passageway travels directly to the compressor.
3. The system of claim 1 wherein the compressor motor is a
brushless motor and the electronic components regulate the output
and commutation of the compressor motor.
4. The system of claim 1 wherein the refrigerant passageway is a
tunnel integrally formed in the heat sink.
5. The system of claim 1 wherein the refrigerant passageway is a
discrete component attached to the heat sink.
6. A method of cooling the electronic components of a compressor
motor in an air conditioning refrigeration system, the system
having a compressor and an evaporator assembly, the method
comprising: mounting the electronic components in heat transfer
relation with a heat sink having a refrigerant passageway; and
directing the vapor refrigerant leaving the evaporator assembly
into the refrigerant passageway of the heat sink before returning
the vapor refrigerant to the compressor.
7. The method of claim 6 wherein the refrigerant returning from the
refrigerant passageway travels directly to the compressor.
8. The method of claim 6 wherein the refrigerant passageway is a
tunnel integrally formed in the heat sink.
9. The method of claim 6 wherein the refrigerant passageway is a
discrete component attached to the heat sink.
10. The method of claim 6 wherein the compressor motor is a
brushless motor.
11. A compressor drive module for an air conditioning refrigeration
system, the refrigeration system including a compressor and an
evaporator assembly connected by a refrigerant line, the compressor
drive module comprising: a motor control unit and a motor, the
motor adapted to drive the compressor; the motor control unit being
electrically connected to the motor, said motor control unit
containing electronic components that control the motor; the
electronic components being mounted in heat transfer relation to a
heat sink; the heat sink including a refrigerant passageway for the
passage of refrigerant there through and being fluidly disposed in
the refrigeration line between the evaporator assembly and
compressor such that refrigerant returning from the evaporator
assembly to the compressor of the air conditioning system travels
directly to the heat sink and through the refrigerant passageway
before reaching the compressor.
12. The compressor drive module of claim 11 wherein the refrigerant
returning from the refrigerant passageway travels directly to the
compressor.
13. The method of claim 11 wherein the refrigerant passageway is a
tunnel integrally formed in the heat sink.
14. The method of claim 11 wherein the refrigerant passageway is a
discrete component attached to the heat sink.
15. The compressor drive module of claim 11 wherein the motor is a
brushless motor and the electronic components regulate the output
and commutation of the compressor motor.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/197,212, filed on Oct. 24, 2008, which is hereby
incorporated by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM ON COMPACT DISC
[0003] Not applicable.
FIELD OF INVENTION
[0004] This invention relates to systems and methods for cooling
the control electronics for a refrigerant compressor drive motor of
an aircraft vapor cycle air conditioning system.
BACKGROUND OF THE INVENTION
[0005] A prior art vapor cycle air conditioning system ("a/c
system") for controlling the environment of an aircraft comprises a
refrigeration circuit including a condenser, evaporator assembly,
expansion device and a motor-driven compressor for moving
refrigerant through the refrigeration circuit. In its simplest form
the evaporation assembly consists of one evaporator. However,
present day a/c systems typically use several evaporators either in
series or parallel arrangement. Hence, as used herein the term
"evaporator assembly" refers to a heat exchanging device, system or
arrangement that comprises one or more evaporators. The typical
compressor motor is a brushed electric motor. However, recent
advances in brushless motors have led to their incorporation in air
conditioning and refrigeration systems. In contrast to brushed
motors using mechanical commutation methods, brushless motors rely
on electronics to effect commutation. Hence, in addition to the
control circuitry required for conventional compressor motors,
brushless motors also require circuitry for commutation.
[0006] Controlling and reducing the heat generated by a/c system
compressor motor control circuitry is a known problem in the prior
art. Accordingly, the additional commutation electronics required
of brushless motors can exacerbate heat generated by the compressor
control circuitry. In passenger transport vehicles like planes, the
motor control electronics are typically contained in their own
housing to protect the electronics from the elements. This housing
inhibits cooling of the electronic components by retaining the heat
generated by them.
[0007] The conventional method of cooling the motor control
electronics of an a/c system is to mount the transistorized
components upon a heat sink. The heat sink of the prior art system
consists of a formed mass of material (typically metal) having good
thermal conductivity. The heat sink is formed with an exaggerated
surface area of fins or baffles to allow a maximum of air or
cooling fluid to circulate over its surface either through
convection or forced air means. In the case of aircraft
applications, the air conditioning systems are required to operate
continuously at ambient temperature of 158 degrees Fahrenheit. The
high ambient requirement plus the heat generated from the
electronic components will generate temperatures inside the
controller that exceed the maximum safe operating temperature of
some components which in some cases may be as low as 185 degrees
Fahrenheit. Keeping the electronics below this maximum limit is
difficult using the conventional method of using a heat sink with
passive or forced air cooling due to size and weight limitations
imposed by aircraft installations.
[0008] Alternatively, it is known in the prior art to fluidly
connect the heat sink to a coolant to absorb heat from the heat
sink and carry it out of the system. It has also been proposed to
use the refrigerant of the a/c loop to cool the compressor motor
control electronics. In this regard, U.S. Pat. No. 5,220,809
proposes shunting a portion of the system refrigerant between a
chill block juxtaposed with the motor control module. The chill
block together with the control module forms a cooling groove that
operates like an evaporator. In this regard, the portion of
refrigerant received by the cooling groove expands to a saturated
vapor and extracts heat from the controller.
[0009] U.S. Pat. No. 6,116,040 discloses an apparatus and method
for cooling the electronics of a variable frequency drive used to
control the motor of a compressor in a refrigeration system.
According to this patent, refrigerant is shunted from the condenser
and out of the refrigeration loop, passed through a heat sink in
heat transfer relation to the motor control electronics and then
returned to the compressor either directly or through the
evaporator. While in the shunt circuit, the refrigerant is expanded
so as to cool the heat sink. The apparatuses disclosed in U.S. Pat.
Nos. 6,116,040 and 5,220,809 have two drawbacks. First, they
require shunting of the refrigerant from the condenser and away
from the evaporator assembly and thus use only a portion of the
refrigerant for electronics cooling. Second, by shunting
refrigerant before the expansion phase, these systems rely on two
phase cooling of the refrigerant and therefore require additional
components and more complicated systems to achieve their
objective.
[0010] U.S. Pat. No. 7,009,318 discloses an electronics cooling
system for an automobile a/c compressor system comprising a
compressor unitarily housed with a motor and the motor electronics.
This patent is directed to attaching the motor control electrical
circuitry to or within the cylindrical outer surface of the
compressor motor housing and including a refrigerant passage
through the housing. The refrigerant is flushed through the housing
and past the electrical motor and then compressed by the
compressor. The heat generated by the electrical components of the
electrical circuit is transferred to the refrigerant passing
through the motor. The system is limitedly useful for those motor
vehicle a/c systems having unitarily housed compressors, motors and
electronics. This system does not address the electronic cooling
needs of environmental control systems such as used in aircraft a/c
systems that have motor control electronics remotely housed from
the motor and compressor. In addition, the cooling capacity of the
refrigerant vis a vis the electronic components is lost upon the
compressor, the motor and those portions of the housing remotely
situated from the heat producing electronic components.
SUMMARY OF THE INVENTION
[0011] This invention seeks to solve the foregoing problems
associated with the electronic cooling methods for prior art a/c
systems. It is therefore an object of the present invention to
provide refrigerant cooling to the control electronics of a motor
driven refrigeration system compressor in a more simplified and
economical manner than currently suggested by the prior art. The
present invention can be more specifically directed to an improved
system and method for cooling the compressor motor control
electronics for an aircraft air conditioning system using a DC
motor drive. The present invention is also directed to an improved
aircraft air conditioning compressor drive module. The invention is
also directed to a system, method and compressor drive module that
provides cooling to both the power and control electronics for a
brushless motor driving an a/c system compressor. The invention is
further directed to a system, method and compressor drive module
that uses cool refrigerant vapor directly from the evaporator
assembly returning in the compressor suction line to cool a heat
sink attached to the motor control electronics. The invention is
further directed to a cooling system, method and compressor drive
module that isolates the electronic controller components from the
compressor drive heat.
[0012] The present invention comprises a refrigeration loop
including a compressor, a condenser, an expansion device and an
evaporator assembly connected by refrigerant lines. A brushless
motor preferably drives the compressor. In such embodiment, motor
operation is governed by both power and commutation electronic
circuitry. This electronic circuitry includes heat producing power
electronic components in the form of mosfets and other
transistorized components that require cooling.
[0013] The motor control electronics are separately housed from the
motor and compressor. Inside the housing, the electronic components
are mounted to a circuit board. The circuit board is juxtaposed in
heat transfer relation to a heat sink. The heat sink is provided
with a refrigerant passageway, preferably an interior tunnel that
has a refrigerant receiving end and a refrigerant discharge end.
These ends are respectively attached to inlet and outlet ports on
the motor control housing. The interior tunnel could include
exaggerated surface area to allow for maximum cooling. The heat
sink is preferably a formed block of material with high thermal
transfer properties. The block acts as a heat sink to draw heat
away from the motor control electronics. The cooling capabilities
of the heat sink are enhanced however by intercepting the flow of
refrigerant directly from the evaporator assembly and delivering it
to the inlet port of the motor control housing. The refrigerant
travels through the tunneled heat sink cooling the electronics
mounted thereon and exits the motor control housing via the outlet
port. The outlet port is fluidly connected to the compressor
intake, and hence the electronic-cooling refrigerant is returned to
the a/c loop via the compressor outlet.
[0014] In contrast to prior art systems, the present invention
system and module delivers refrigerant directly from the evaporator
assembly to a dedicated heat sink that is attached to or is
otherwise in heat transfer relation with the motor control
electronics. As such, it dispenses with the need to provide a
separate flow circuit to pass refrigerant from the system condenser
to the compressor control electronics. It also, dispenses with the
need to provide phase changing devices in the form of heat sinks
and expansion valves in the separate flow circuit. By delivering
the refrigerant directly to a dedicated heat sink juxtaposed with
the motor control electronics, the electronic component cooling
capacity of the refrigerant is maximized and not lost on ancillary
structures like the compressor, the compressor motor or remote
housing surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic representation of an a/c system
incorporating the present invention motor control cooling system
and apparatus.
[0016] FIG. 2 is a perspective view of the exterior of the present
invention motor control unit adapted to receive expanded
refrigerant gas directly from the evaporator assembly of an a/c
loop, pass that refrigerant through a housed heat sink and
discharge that refrigerant to the suction port of the refrigeration
loop compressor.
[0017] FIG. 3 is a perspective view of the motor control circuitry
of the present invention motor control unit of FIG. 1 mounted in
heat transfer relation to a heat sink adapted to directly receive
expanded refrigerant gas from the evaporator assembly of an a/c
loop and transmit it to the compressor.
[0018] FIG. 4 is an exploded perspective view of the interior of
the present invention motor control unit of FIG. 1 showing the
motor control circuitry and heat sink adapted to directly receive
and transmit expanded refrigerant gas from the evaporator assembly
of an a/c loop to the compressor.
[0019] FIG. 5 is a perspective view of an aircraft a/c compressor
drive module incorporating the present invention motor control
cooling system and apparatus.
[0020] FIG. 6 is an alternate perspective view of the aircraft a/c
compressor drive module of FIG. 5.
[0021] FIG. 7 is an overhead plan view of the aircraft a/c
compressor drive module of FIG. 5.
[0022] FIG. 8 is a bottom plan view of the aircraft a/c compressor
drive module of FIG. 5.
[0023] FIG. 9 is a left side elevation view of the aircraft a/c
compressor drive module of FIG. 5.
[0024] FIG. 10 is a right side elevation view of the aircraft a/c
compressor drive module of FIG. 5.
[0025] FIG. 11 is a rear elevation view of the aircraft a/c
compressor drive module of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] FIG. 1 depicts an aircraft a/c system 10 comprising the
system and method for cooling the electronic components for the
controller of a compressor motor, which in the preferred embodiment
is a brushless motor. System 10 constitutes a loop or circuit that
includes refrigerant lines 12a, 12b, 12c, 12d and 12e. These lines
fluidly connect the various system components. The system further
includes conventional a/c loop components, whose function is well
known in the art, such as condenser 13, compressor 15 and
evaporator assembly 17. Line 12a connects discharge outlet 14 of
compressor 15 to condenser 13. Refrigerant flows from condenser 13
to expansion device 20 via line 12b. Expansion device 20 expands
high pressure refrigerant leaving condenser 13 to a lower
temperature and pressure. The expansion devices known in the prior
art include throttling valves or capillary tubes. After leaving
expansion device 20 the refrigerant travels via line 12c to
evaporator assembly 17, where the refrigerant undergoes a low
pressure phase change from liquid to vapor via absorption of heat
from the walls of evaporator coils that are in heat transfer
relation to ambient air pushed past the evaporator coils by a
blower 18. In the conventional prior art a/c system loop,
refrigerant (in vapor phase) would leave evaporator assembly 17 and
proceed directly via refrigerant line 12d to suction port 16 of
compressor 15, thereby completing the system loop. Compressor 15
intakes the vapor refrigerant and recirculates it through the
system via outlet port 14.
[0027] As shown in FIG. 1, in the present invention system, line
12d leaving evaporator assembly 17 does not directly lead to
compressor 15. Instead, evaporator assembly 17 is fluidly connected
by line 12d to compressor motor control unit 29, interposed between
evaporator assembly 17 and compressor 15. Line 12e, in turn,
connects motor control unit 29 to the suction inlet port 16 of
compressor 15.
[0028] FIG. 2 shows a preferred embodiment motor control unit 29.
Motor control unit 29 contains power and commutation electronic
components that control the operation of a brushless DC compressor
motor. These electronic components, typically mosfets or other
transistors, are represented by reference numeral 27 in the
drawings. The prior art method of cooling control electronics 27 in
an aircraft a/c system would involve mounting the electronics to a
metal multi-baffled heat sink designed to radiate heat to ambient
air. However, the additional electronics necessitated for
commutation of a brushless motor increase the heat production of
the control electronics. This increased heat production requires
enhanced cooling measures, that due to avionics conditions, also do
not require significant space.
[0029] FIG. 3 shows the motor control circuitry, including
heat-producing components 27, of the present invention motor
control unit 29 mounted in juxtaposition to a heat sink 30. Heat
sink 30 is adapted to receive and transmit expanded refrigerant
vapor from evaporator assembly 17 of a/c loop 10 to compressor 15.
FIG. 4 shows the motor control circuitry and heat sink in exploded
view. As illustrated in these figures, electronic components 27 of
motor control unit 29 are mounted upon printed circuit board 28
which is directly attached to heat sink 30, which in the preferred
embodiment forms the floor of motor control unit 29. Heat sink 30
is preferably fabricated from a block of metallic material that has
a high coefficient of thermal conductivity such that the heat
energy generated by the power electronic components is rapidly
drawn away from and absorbed into the heat sink. Heat sink 30
includes refrigerant passageway 32, which in the preferred
embodiment is a tunnel formed within the block of material.
Refrigerant tunnel 32 includes refrigerant receiving end 33 and
refrigerant discharge end 34. Preferably, tunnel 32 has an
exaggerated (for example, grooved, pitted, dimpled or formed with
pockets) interior surface and defines a serpentine route through
heat sink 30 to maximize refrigerant-to-heat sink contact surface
area. In the preferred embodiment, refrigerant tunnel 32 is
integrally formed within heat sink 30. Alternatively, heat sink 30
and tunnel 32 could be composed of discrete components such as a
metallic slab or strut and conjoined tubing respectively. By
utilizing the refrigeration loop to remove heat from the motor
control electronics, the heat transferred to the refrigerant is
moved by a/c system compressor 15 to condenser 13 where it is
discharged out of the a/c loop. The disclosed method thus employs a
low pressure drop refrigerant path to minimize loss of system
operating efficiency.
[0030] By providing heat sink 30 with refrigerant passageway 32 and
using refrigerant for cooling, heat sink 30 can be made smaller
than the heat sink found in prior art a/c systems. Alternatively,
by adding rifling or fins to heat sink 30, its cooling properties
can be enhanced. Heat sink 30 may also include sensors to provide
temperature and pressure control feedback. The cooling
effectiveness of heat sink 30 may be further enhanced by having
returning refrigerant achieve multiple passes through the heat
sink. Similarly, the cooling effectiveness of heat sink 30 may be
enhanced by directly attaching the control electronics to it with
electrical isolation.
[0031] Refrigerant receiving end 33 of tunnel 32 is connected to
evaporator assembly 17 by supply line 12d. Tunnel 32 and line 12d
interface at inlet port 35 situated on the housing 40 of motor
control unit 29. Refrigerant discharge end 34 of tunnel 32
interfaces with line 12e at outlet port 36 situated on housing 40.
Line 12e leads to inlet port 16 of compressor 15.
[0032] FIGS. 5-11 show a preferred embodiment aircraft a/c
compressor drive module 50 incorporating the present invention
motor control cooling system. Compressor drive module 50 includes
isolated motor control unit 29, brushless DC motor 52 and
compressor 15 mounted upon base 45. In the depicted embodiment
compressor 15 is belt driven by motor 52, but the two components
could be in direct drive arrangement. Motor control unit 29
includes motor input power connection 55 and motor ground
connection 56. Though in the disclosed compressor drive module heat
sink 30 is part of isolated motor control unit 29, heat sink 30 may
be formed as an integral part of the compressor housing. In the
depicted embodiment, compressor 15 may include high and low
pressure sensors 98, 99 electrically connected to motor control
unit 29.
[0033] The cooling system and method disclosed above provides
improved cooling to the isolated motor control electronic
components of an a/c refrigerant loop. While it is particularly
adapted to a system employing a DC current brushless motor to drive
the compressor, it can be used in systems utilizing brushed motors
controlled by electronics. The present invention system delivers
cooling refrigerant directly from an evaporator assembly to the
control electronics. It thereby dispenses with the need to provide
a separate flow circuit to pass refrigerant from the system
condenser to the compressor control electronics. Likewise, the
present invention system dispenses with the need to provide phase
changing devices in the form of heat sinks or expansion valves in
the separate flow circuit. It accomplishes the foregoing without
adding any significant spacing requirement to the motor control
unit.
[0034] While this invention has been explained with reference to
the structure disclosed herein, it is not confined to the details
set forth and this invention is intended to cover any modifications
and changes as may come within the scope of the following
claims.
* * * * *