AU2012203057B2 - Compressor assembly having electronics cooling system and method - Google Patents

Abstract

C:\NRPonbrDCC\DER\4349215_ .DOC-24/5/2012 A compressor for an air conditioning system or a heat pump system carrying a refrigerant, comprising: a shell including a suction line for receiving low-pressure refrigerant and a discharge line for discharging high-pressure refrigerant; an electronics module proximate said shell; a cooling apparatus proximate said electronics module that utilizes said low pressure refrigerant to cool said electronics module; and a temperature sensor adjacent said cooling apparatus and in communication with said electronics module, and for detecting a temperature of said low-pressure refrigerant.

Description

Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (ORIGINAL) Name of Applicant: Emerson Climate Technologies, Inc., of 1675 W. Campbell Rd., Sidney, Ohio 45365-0669, United States of America Actual Inventor: CAILLAT, Jean-luc M. Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, of I Nicholson Street, Melbourne 3000, Victoria, Australia Invention Title: Compressor assembly having electronics cooling system and method The following statement is a full description of this invention, including the best method of performing it known to us: C \NRPonbl\DCC\DER\4349232_ DOC - 24/5/12 itsmsiieruoen\NRPorhDCCS5PM\6 719_ldoc-25/06/21D14 COMPRESSOR ASSEMBLY HAVING ELECTRONICS COOLING SYSTEM AND METHOD FIELD The present disclosure relates to a method, to a system, or to a compressor for an air conditioning system or a heat pump system, e.g., that utilises refrigerant to cool system electronics. BACKGROUND The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. A compressor may use electronics to control the compressor motor. The electronics may be externally mounted to the outer shell of the compressor, and used to modulate compressor capacity, such as by varying the speed of the motor. During operation, however, the electronics may generate heat. If too much heat is generated, the electronics may overheat. It is desired to address or ameliorate one or more disadvantages or limitations associated with the prior art, or to at least provide a useful alternative. SUMMARY In accordance with the present invention there is provided a compressor for an air conditioning system or a heat pump system carrying a refrigerant, comprising: a shell including a suction line for rccciving low-pressure refrigerant and a discharge line for discharging high-pressure refrigerant; an electronics module proximate said shell; a cooling apparatus proximate said electronics module that utilizes said low pressure refrigerant to cool said electronics module; a control module; and a temperature sensor adjacent said cooling apparatus and in communication with Sspininero nNRPorhIblCC\SPM\64357 9I doc-25/06/2014 -2 said control module, and for detecting a temperature of said low-pressure refrigerant entering said cooling apparatus, wherein said control module minimizes an amount of said low-pressure refrigerant in a liquid phase passing through said cooling apparatus to cool said electronics module based on said temperature. The present invention also provides a system comprising: a pair of heat exchangers in communication with said compressor; an expansion valve disposed between said heat exchangers; a temperature sensor for detecting a temperature of said low-pressure refrigerant passing through the system; the compressor above; a cooling apparatus for receiving said low-pressure refrigerant; and an electronics module adjacent said cooling apparatus, in communication with said temperature sensor, and controlling said expansion valve based on said temperature of said low-pressure refrigerant to control an amount of said low-pressure refrigerant passing through said cooling apparatus. The present invention also provides a method comprising cooling an electronics module that is externally mounted to a compressor using a cooling apparatus mounted to said electronics module with a low-pressure refrigerant that passes through said cooling apparatus, said step of cooling including monitoring a temperature of said low-pressure refrigerant with a temperature sensor located at an inlet of said cooling apparatus, said temperature sensor being in communication with a control module that minimizes a flow of said low-pressure refrigerant in a liquid phase entering said cooling apparatus based on said temperature. DRAWINGS Preferred embodiments of the present invention are hereinafter described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of an air conditioning or heat pump system: Figure 2 is a perspective view of a compressor and its corresponding electronics i le en RPoribDII SPNI 64i719_1do-2i506/2014 module having a cooling apparatus; and Figure 3 is a cross-sectional view of a conduit in the air conditioning or heat pump system, illustrating the transition of the refrigerant from a liquid phase to a gaseous phase. DETAILED DESCRIPTION Embodiments of the present invention may provide a compressor for an air conditioning system or a heat pump system carrying a refrigerant, comprising: a shell including a suction line for receiving low-pressure refrigerant and a discharge line for discharging high-pressure refrigerant; an electronics module proximate said shell; a cooling apparatus proximate said electronics module that utilizes said low pressure refrigerant to cool said electronics module; and a temperature sensor adjacent said cooling apparatus and in communication with said electronics module, and for detecting a temperature of said low-pressure refrigerant. In the system described above, the electronics module may control a liquid dry out point (LDOP) of the low-pressure refrigerant. Also, the electronics module may control superheating of the low-pressure refrigerant. If the sensor detects a decrease in temperature of the low-pressure refrigerant, the electronics module may cause the expansion valve to decrease an amount of refrigerant allowed to reach one of the heat exchangers. If the sensor detects an increase in temperature of the low-pressure refrigerant, the electronics module may cause the expansion valve to increase an amount of refrigerant allowed to reach one of the heat exchangers. The temperature sensor may be disposed adjacent the cooling apparatus. Alternatively, the temperature sensor may be disposed at an inlet of the cooling apparatus. In yet another alternative, the temperature sensor is disposed downstream of an H I nlemoeNRIorlbl\DC C\SPM\6~l4M7B 19 _Edoc-25/06/2014 -4 inlet of the cooling apparatus. The cooling apparatus may include a cold plate having a plurality of passageways for carrying the low-pressure refrigerant. Moreover, the compressor may be a variable speed compressor. Further, the electronics module may include an inverter. Embodiments of the present invention may provide a system comprising: a pair of heat exchangers in communication with said compressor; an expansion valve disposed between said heat exchangers; a temperature sensor for detecting a temperature of said low-pressure refrigerant passing through the system; the compressor as defined above; a cooling apparatus for receiving said low-pressure refrigerant; and an electronics module adjacent said cooling apparatus, in communication with said temperature sensor, and controlling said expansion valve based on said temperature of said low-pressure refrigerant to control an amount of said low-pressure refrigerant passing through said cooling apparatus. Embodiments of the present invention may provide a method comprising: monitoring a temperature of a low-pressure refrigerant with a temperature sensor in communication with an electronics module; controlling with said electronics module a flow of said low-pressure refrigerant based on said temperature; and cooling said electronics module with said low-pressure refrigerant. 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. 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 IS \ 79 doc-25/06/2014 -5 drawings, corresponding reference numerals indicate like or corresponding parts and features. Figure 1 is a schematic representation of an air conditioning or heat pump system 10. Air conditioning of heat pump system 10 may generally include a compressor 12, a condenser 14, and an evaporator 16. Disposed between condenser 14 and evaporator 16 may be an expansion valve 18. Air conditioning or heat pump system 10 may also be provided with a reversing valve 20 where suction and discharge lines 22 and 24, respectively, pass through. Reversing valve 20 allows system 10 to operate as either a refrigeration system or a heat pump. Regardless whether system 10 operates as a refrigeration system or as a heat pump, compressor 12 receives low-pressure refrigerant at a suction side and dispenses high-pressure refrigerant at a discharge side. When operating as a refrigeration system, system 10 uses the cooling effect of evaporation of the refrigerant to lower the temperature of the surroundings near one heat exchanger (i.e., evaporator 16) and uses the heating effect of high pressure, high temperature gas to raise the temperature of the surroundings near another heat exchanger (i.e., condenser 14). This is usually accomplished by releasing a refrigerant under pressure (usually in a liquid phase) into a low pressure region to cause the refrigerant to expand into a low temperature mixture of liquid and vapor. Commonly, this low pressure region comprises a coil (not shown) that acts as an evaporator, that may be formed in evaporator 16. Once in the evaporator coil, the refrigerant mixture may exchange heat with the tubing of the coil, which in turn exchanges heat with high temperature ambient air of the region desired to be cooled. Evaporation of refrigerant from liquid to gas absorbs heat from the ambient air and thereby cools it. [0048] Release of refrigerant into the low pressure evaporator coil is usually metered by expansion valve 18. There are a wide variety of different types of expansion valves in use today, ranging from simple non-adjustable capillary tubes or orifices to electrically adjustable valves, such as pulse width modulated valves and stepper motor valves. [0049] The refrigerant at the output of evaporator 16 is compressed back into a high pressure state by compressor 12 and is condensed into a liquid phase by condenser 14 so that it may be used again. In some systems, compressor 12 may be variable speed or variable capacity, so that the compressor 12 also controls the rate at which refrigerant flows through the restricted orifice. To operate compressor 12 at variable speed or variable capacity, compressor 12 may include an electronics module 26, including an electronic inverter. [0050] Electronic inverter, which may also be referred to as a variable frequency drive (VFD), receives electrical power from a power supply and delivers electrical power to compressor 12. By modulating the frequency of electrical power delivered to the electric motor of compressor 12, inverter may thereby modulate and control the speed, and consequently the capacity, of compressor 12. To modulate the frequency of electric power, inverter may include solid state electronics to modulate the frequency of electrical power. Generally, inverter more specifically comprises a converter that converts the 6 inputted electrical power from AC to DC, and then inverter converts the electrical power from DC back to AC at a desired frequency. [0051] Figure 2 illustrates an exemplary compressor 12 having electronics module 26 mounted thereto. Electronics module 26 includes an electrical enclosure or housing 28 that houses various electronic components such as a control module 30. Control module 30, such as Assignee's U.S. Pat. No. 6,302,654, which is hereby incorporated by reference in its entirety, may control compressor capacity or monitor operating conditions of the compressor. [0052] Control module 30 may generally include a control block, microprocessor, memory analog-to-digital converters, a communication interface, the inverter described above, and a plurality of terminals connected to various sensors that monitor parameters of the compressor. The control block, which includes processing circuitry, may control compressor capacity. The analog-to-digital converter may be used to convert analog signals sent by the various sensors to a digital signal before input into control module 30. The communication interface may provide communication with the control block from an outside source or server via, for example, an internet or intranet connection. [0053] Electronics module 26 may also house a compressor protection or diagnostic system that may include controller 30, such as that described above, and a power interruption system (not shown). Diagnostic system may include a plurality of sensors, and diagnoses operating conditions by receiving and analyzing motor, compressor, and system parameters. In addition, the diagnostic data may be used to control compressor modulation based on system conditions detected by the sensors. An exemplary compressor protection and control diagnostic systems is described in the assignee's commonly owned U.S. Pat. Application Serial No. 11/059,646 filed on February 16, 2005, and U.S. Pat. No. 6,615,594 which are hereby incorporated by reference in their entirety. [0054] As system 10 operates, the components of electronics module 26 may generate heat. As more heat is generated, however, the components (e.g., inverter components) of electronics module 26 may overheat and cause system 10 to either shutdown or reduce capacity until the components cool, or the components may not operate correctly and cause system 10 to malfunction 7 or fail. To reduce the possibility that the components of electronics module 26 may fail due to overheating, steps may be taken to cool electronics module. [0055] Again referring to Figure 2, a cooling apparatus 50 may be mounted to electronics module 26 to cool electronics module 26. Cooling apparatus 50 may be a cold plate that may include a generally planar member 52 that includes a plurality of pathways 54. The pathways 54 are configured to support a tubular assembly 56 that carries the refrigerant therein. Refrigerant passing through tubular assembly 56 and planar member 52 absorbs heat generated by the electronics module 26 that is passed from the electronics assembly 26 to planar member 52. In this manner, heat generated by the electronics module 26 may be efficiently transferred to the refrigerant (i.e., a suction gas) flowing through the cooling apparatus 50 to cool electronics module 26. (00561 At an inlet 58 of cooling apparatus 50 within a suction line 60 from system 10 may be disposed a temperature sensor 62. Although temperature sensor 62 is Illustrated as being disposed upstream at inlet 58 in Figure 2, the present disclosure should not be limited thereto. Temperature sensor 62, rather, may be disposed upstream of inlet 58, adjacent inlet 58, or downstream of inlet 58 within cooling apparatus 50. Regardless, temperature sensor 62 senses a temperature of the suction line 60 refrigerant, indicating conditions prior to or after the refrigerant enters cooling apparatus 50, and communicates temperatures of the refrigerant in suction line 60 to electronics module 26. Fluctuations in temperature of the refrigerant detected by temperature sensor 62 and communicated to electronics module 26 may by used to control expansion valve 18 to either increase or decrease the amount of refrigerant entering evaporator 16. That is, electronics module 26 is also in communication with expansion valve 18 to control an amount of refrigerant entering evaporator 16 through expansion valve 18. By controlling expansion valve 18 based on a temperature of the refrigerant detected by temperature sensor 62, the amount of refrigerant entering evaporator 16 may be controlled to enhance the cooling effect of cooling apparatus 50 on electronics module 26. 8 [0057] Furthermore, by controlling expansion valve 18, a liquid dry out point (LDOP) of the refrigerant in system 10 may be controlled. LDOP is described in assignee's U.S. Pat. No. 5,502,970, which is hereby Incorporated by reference in its entirety. LDOP operates on a principle that a refrigerant flow pattern develops as the refrigerant acquires heat in the coils 64 of evaporator 16 and ultimately makes a transition from liquid to vapor. Referring to Figure 3, a section of the evaporator coil 64 of evaporator 16 is illustrated. Specifically, a portion adjacent to an exit end of coil 64 has been illustrated, In magnified form, to show how the refrigerant changes state as heat is absorbed.

[0058] In Region a, the refrigerant is principally in the liquid phase with some suspended bubbles of refrigerant in the vapor phase. The bubbles tend to flow along the top of the coil, as illustrated. As heat is absorbed, the refrigerant gradually exhibits the flow Illustrated in Region b. In Region b, bullet-shaped bubbles form and tend to move along the top of the coil as Illustrated. [0059] As the flow proceeds to Region c, the refrigerant enters a stratified flow regime, characterized by liquid refrigerant flowing along the bottom of the coil and vapor refrigerant flowing along the top. As further heat energy is absorbed by the refrigerant, the liquid refrigerant develops waves that are depicted in Region d. These waves are formed on the liquid/vapor interface through the increased velocity of the vaporous refrigerant. [0060] Next, the slug flow regime develops as illustrated in Region e. The waves and the liquid refrigerant grow large enough to touch the upper surface of the coil, with large frothy slugs of liquid interspersed with regions of stratified liquid flow. Finally, in Region f virtually all of the refrigerant is in the vapor phase and the flow become annular. The liquid refrigerant adheres to the sidewall of the coil with a greater quantity present at a bottom of a coil due to gravitational effect. [0061] The LDOP or "burn out" point occurs when the liquid phase adhering to the sidewalls substantially disappears. The LDOP is illustrated generally at Region g in Figure 3. The precise location of the LDOP, however, will shift randomly or erratically back and forth (i.e., left to right in Figure 3) as system 10 operates. 9 [0062] Utilizing the LOOP concept, sensor 62 is disposed at a location adjacent inlet 58 of cooling apparatus 50 so that if a minimum amount of liquid refrigerant advances to the location of sensor 62 (i.e., the LOOP moves downstream of sensor 62 towards cooling apparatus 50), a sudden change of temperature may be detected by sensor 62 (because liquid refrigerant generally has a temperature less than gaseous refrigerant). If such a change in temperature is detected by sensor 62 and communicated to electronics module 26, electronics module 26 may then communicate with expansion valve 18 to reduce the amount of refrigerant flowing to evaporator 16. Reducing the amount of refrigerant flowing to evaporator 16 may move the LOOP upstream of sensor 62. [0063] In contrast, when the temperature of the refrigerant detected by sensor 62 increases, indicating that the LOOP is upstream of sensor 62, expansion valve 18 may be controlled by electronics module 26 to increases the flow of the refrigerant to evaporator 16 to move the LOOP back downstream towards sensor 62. In this manner, the refrigerant flow may be controlled through evaporator 16 to control the LOOP by controlling expansion valve 18. By controlling the LDOP such that the LOOP is essentially at the location of sensor 62, a minimum amount of liquid refrigerant may enter cooling apparatus 50. [0064] Controlling expansion valve 18 based on fluctuation of the LOOP also allows for minimum superheating of the refrigerant, which improves performance of the heat exchange surface of evaporator 16, This, in turn, enables the size of evaporator 16 to be minimized. Furthermore, due to the minimum superheating of the refrigerant, lower temperature cooling of the electronic module 26 may be achieved. This lower temperature cooling of electronics module 36, compared to using condensed liquid as used in conventional refrigerant systems, may result in lower cost electronics. Moreover, controlling expansion valve 18 so that the LOOP stays upstream of cooling apparatus 50 minimizes temperature fluctuations experienced by electronics module 26. 10 [0065] Additionally, condensation that may form on electronics module 26 and cooling apparatus 50 may be kept minimal since electronics module 26 may be cooled in accordance with operation of compressor 12. That is, as capacity of compressor 12 increases, operation of expansion valve 18 may be controlled to maximize the amount of refrigerant entering evaporator 16 and cooling apparatus 50 to cool electronics module 26. [0066] Using LDOP also enables cooling apparatus 50 to be sized such that minimization of electronics module 26 is possible by ensuring lower solid-state electronic component (not shown) junction temperature. Electronics module 26 used by system 10 may have electronic components with a maximum current rating limited by its junction temperature, Tj. In general, Tj should not exceed 160 degrees C and, generally, Ti is about 150 degrees C at a given solid-state packaging case temperature, Tc. Case temperature affects the maximum current rating of the solid-state switch. For example, the solid-state switches may be rated at 60 amperes at a Tc of 25 degrees C and rated at 30 amperes at a Tc of 100 degrees C. This difference in current rating results from thermal resistance at the junction of the solid-state switch and its packaging. [0067] A Tc of 25 degrees Celsius may not be obtained at full current rating using only forced convection of air on a typical heat sink in contact with the packaging case, let alone by using natural convection. Tc of 100 degrees C, however, is more readily observed using these methods and, therefore, current ratings of about 30 amperes are generally achieved using forced convection and natural convection of air on a heat sink with contact with the packaging case. By using refrigerant cooling and controlling the LDOP by controlling the expansion valve 18, however, the amount of cooling that cooling apparatus 50 may exhibit on electronics module 26 and housing 28 may extend the current rating to about 39 amperes (i.e., a 30 percent increase). That is, cooling apparatus 50 having gaseous refrigerant passing therethrough based on controlling the LDOP results in a lower electronic component junction temperature that allows solid-state switch, and therefore electronics module 26, to operate at a higher current rating. Because the current rating may be raised in this manner, the cost of running 11 C:\NRPortbRDCC\DER\43492I 5_.DOC24/05O212 - 12 system 10 may be reduced, and the cost of the electronics used for electronics module 26 may be reduced. 100681 The above description is merely exemplary in nature and, thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the present teachings. Such variations are not to be regarded as a departure from the spirit and scope of the present teachings. 100691 The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. [00701 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (21)

1. A compressor for an air conditioning system or a heat pump system carrying a refrigerant, comprising: a shell including a suction line for receiving low-pressure refrigerant and a discharge line for discharging high-pressure refrigerant; an electronics module proximate said shell; a cooling apparatus proximate said electronics module that utilizes said low pressure refrigerant to cool said electronics module; a control module; and a temperature sensor adjacent said cooling apparatus and in communication with said control module, and for detecting a temperature of said low-pressure refrigerant entering said cooling apparatus, wherein said control module minimizes an amount of said low-pressure refrigerant in a liquid phase passing through said cooling apparatus to cool said electronics module based on said temperature.

2. The compressor of claim 1, wherein said control module controls a liquid dry out point (LDOP) of said low-pressure refrigerant.

3. The compressor of claim 1, wherein said control module controls superheating of said low-pressure refrigerant.

4. The compressor of claim 1, further comprising: a pair of heat exchangers in communication with said compressor; and an expansion valve disposed between said heat exchangers, said expansion valve being controlled by said control module, wherein if said sensor detects a decrease in temperature of said low-pressure refrigerant, said control module causes said expansion valve to decrease an amount of refrigerant allowed to reach one of said heat exchangers. 11 spanInleruo'enNRIortbl\DCC\SPI\64357I9_I doc-25/06/2114 - 14

5. The compressor of claim 1, further comprising: a pair of heat exchangers in communication with said compressor; and an expansion valve disposed between said heat exchangers, said expansion valve being controlled by said control module, wherein if said sensor detects an increase in temperature of said refrigerant, said control module causes said expansion valve to increase an amount of refrigerant allowed to reach one of said heat exchangers.

6. The compressor of claim 1, wherein said temperature sensor is disposed adjacent said cooling apparatus.

7. The compressor of claim 1, wherein said temperature sensor is disposed at an inlet of said cooling apparatus.

8. The compressor of claim 1, wherein said temperature sensor is disposed downstream of an inlet of said cooling apparatus.

9. The compressor of claim 1, wherein said cooling apparatus comprises a cold plate having a plurality of passageways for carrying said low-pressure refrigerant.

10. The compressor of claim 1, wherein said control module controls an amount of the refrigerant passing through said cooling apparatus.

11. The compressor of claim 1, wherein said compressor is a variable speed compressor.

12. The compressor of claim 1, wherein said electronics module includes an inverter.

13. A system comprising: a pair of heat exchangers in communication with said compressor; an expansion valve disposed between said heat exchangers; I \ pmntcuve\RIrbiD C\P \6379_.doc-25/016/214 - 15 a temperature sensor for detecting a temperature of said low-pressure refrigerant passing through the system; the compressor of any one of claims 1-12; a cooling apparatus for receiving said low-pressure refrigerant; and an electronics module adjacent said cooling apparatus, in communication with said temperature sensor, and controlling said expansion valve based on said temperature of said low-pressure refrigerant to control an amount of said low-pressure refrigerant passing through said cooling apparatus.

14. A method comprising cooling an electronics module that is externally mounted to a compressor using a cooling apparatus mounted to said electronics module with a low pressure refrigerant that passes through said cooling apparatus, said step of cooling including monitoring a temperature of said low-pressure refrigerant with a temperature sensor located at an inlet of said cooling apparatus, said temperature sensor being in communication with a control module that minimizes a flow of said low-pressure refrigerant in a liquid phase entering said cooling apparatus based on said temperature.

15. The method of claim 14, wherein controlling said flow controls a LDOP of said low-pressure refrigerant.

16. The method of claim 15, wherein controlling said LDOP controls superheating of said low-pressure refrigerant.

17. The method of claim 14, wherein if said sensor detects a decrease in temperature of said low-pressure refrigerant, said control module decreases said flow of low-pressure refrigerant.

18. The method of claim 14, wherein if said sensor detects an increase in temperature of said low-pressure refrigerant, said control module increases said flow of low-pressure refrigerant. H1 \ i NRPortbiD(C SPM643571,_ 1 (c-25/16/2014 - 16

19. The method of claim 14, wherein said electronics module includes an inverter.

20. The method of claim 14, further comprising compressing said refrigerant with a variable speed compressor.

21. A compressor for an air conditioning system or a heat pump system carrying a refrigerant, the compressor substantially as hereinbefore described with reference to the accompanying drawings and/or examples; or a method comprising cooling an electronics module that is externally mounted to a compressor using a cooling apparatus mounted to said electronics module with a low-pressure refrigerant that passes through said cooling apparatus, the method substantially as hereinbefore described with reference to the accompanying drawings and/or examples.