System and method for cooling power electronics using heat sinks

• US 8,950,201 B2
• Filed: 03/30/2012
• Issued: 02/10/2015
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: Trane International Inc. (Trane Technologies plc)
• Inventors: Voorhis, Roger J.
• Primary Examiner(s): Tyler, Cheryl J
• Assistant Examiner(s): VAZQUEZ, ANA M
• Application Number:
  US13/435,653
• Publication Number:
  US 20130255292A1
• Time in Patent Office: 1,047 Days
• Field of Search: 621/17, 622/592, 622/381, 625/13, 621/13, 621/15
• US Class Current: 62/117
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2313/021 Indoor unit or outdoor unit with auxiliary heat exchanger not forming part of the indoor or outdoor unit
• CPC Class Codes: F25B 2313/02741 using one four-way valve
• CPC Class Codes: F25B 2400/077 Compressor control units, e.g. terminal boxes, mounted on the compressor casing wall containing for example starter, protection switches or connector contacts
• CPC Class Codes: F25B 30/06 characterised by the source of low potential heat
• CPC Class Codes: F25B 31/006 Cooling of compressor or motor
• CPC Class Codes: F25B 41/20 Disposition of valves, e.g. of on-off valves or flow control valves expansion valves F25B41/31
• CPC Class Codes: F25B 5/02 arranged in parallel

Abstract

A heat pump includes a main refrigerant circuit having a compressor, an indoor heat exchanger, and an outdoor heat exchanger, and a reversing valve. A biflow expansion valve is configured to receive condensed liquid refrigerant and to expand the refrigerant. A cooling circuit in fluid communication with the main refrigerant line includes an expansion device configured to receive a portion of condensed liquid refrigerant from the main refrigerant circuit and to expand the portion of condensed liquid refrigerant. A heat sink is configured to receive the expanded portion of refrigerant from the expansion device. Power electronics are coupled to the heat sink such that the portion of expanded refrigerant from the expansion device passes through the heat sink and cools the power electronics.

Claims

1. A heat pump comprising:

a main refrigerant circuit including

a compressor configured to compress a refrigerant,

an indoor heat exchanger,

an outdoor heat exchanger,

a biflow expansion valve configured to receive condensed liquid refrigerant and to expand the refrigerant,

a reversing valve movable between a first position that directs refrigerant from the compressor sequentially to the outdoor heat exchanger, the biflow expansion valve, and the indoor heat exchanger in a cooling mode, and a second position that directs compressed refrigerant from the compressor sequentially to the indoor heat exchanger, the biflow expansion valve, and the outdoor heat exchanger in a heating mode; and

a cooling circuit in fluid communication with the main refrigerant line, the cooling circuit including

a heat sink configured to receive expanded refrigerant,

an expansion device configured to receive a portion of condensed liquid refrigerant from the main refrigerant circuit, the expansion device including a first orifice check valve disposed between the heat sink and a first branch point on the main refrigerant circuit between the indoor heat exchanger and the biflow expansion valve, and a second orifice check valve disposed between the heat sink and a second branch point on the main refrigerant circuit between the outdoor heat exchanger and the biflow expansion valve,

the first orifice check valve is configured to expand the portion of condensed refrigerant in the heating mode,

and

power electronics coupled to the heat sink, the portion of expanded refrigerant from the expansion device passing through the heat sink and cooling the power electronics,

the main refrigerant circuit further includes a suction line with a third branch point between the reversing valve and the compressor,

the cooling circuit further includes a branch line that fluidly connects the heat sink to the third branch point of the suction line, and

wherein the second orifice check valve in the heating mode is configured to inhibit passage of the portion of expanded refrigerant from the first orifice check valve to the second branch point such that the portion of expanded refrigerant is directed to the suction line through the branch line to mix with refrigerant evaporated by the outdoor heat exchanger.

2. The heat pump of claim 1, wherein the power electronics are variable frequency drive (VFD) components.

3. The heat pump of claim 2, wherein the compressor is a variable speed compressor and the VFD components control the speed of the compressor.

4. The heat pump of claim 2, further comprising a supply air fan configured to force air through the indoor heat exchanger, the supply air fan driven by a variable speed motor, wherein the VFD components control the speed of the variable speed motor.

5. The heat pump of claim 1, wherein the biflow expansion valve is a thermostatic expansion valve having a 15% bleed.

6. The heat pump of claim 1, wherein the expansion device of the cooling circuit is a fixed orifice valve.

7. A heat pump comprising:

a main refrigerant circuit including

a compressor configured to compress a refrigerant,

an indoor heat exchanger,

an outdoor heat exchanger,

at least one expansion valve configured to receive condensed liquid refrigerant and to expand the refrigerant,

a reversing valve movable between a first position that directs refrigerant from the compressor sequentially to the outdoor heat exchanger, the at least one expansion valve, and the indoor heat exchanger in a cooling mode, and a second position that directs compressed refrigerant from the compressor sequentially to the indoor heat exchanger, the at least one expansion valve, and the outdoor heat exchanger in a heating mode; and

a cooling circuit in fluid communication with the main refrigerant line, the cooling circuit including

a heat sink configured to receive expanded refrigerant,

a first orifice check valve disposed between the heat sink and a first branch point on the main refrigerant circuit between the indoor heat exchanger and the at least one expansion valve,

a second orifice check valve disposed between the heat sink and a second branch point on the main refrigerant circuit between the outdoor heat exchanger and the at least one expansion valve,

wherein each of the first and second orifice check valves is configured to receive a portion of condensed liquid refrigerant from the main refrigerant circuit and to expand the portion of condensed liquid refrigerant, the first orifice check valve is configured to expand the portion of condensed liquid refrigerant in the heating mode, and

power electronics coupled to the heat sink, the portion of expanded refrigerant from one of the first orifice check valve and the second orifice check valve passing through the heat sink and cooling the power electronics,

the main refrigerant circuit includes a suction line between the reversing valve and the compressor, and

the cooling circuit further includes a branch line that fluidly connects the heat sink to a third branch point on the suction line, and

wherein the second orifice check valve is configured to inhibit passage of the portion of expanded refrigerant from the first orifice check valve to the second branch point such that the portion of expanded refrigerant is directed to the suction line through the branch line to mix with refrigerant evaporated by the outdoor heat exchanger.

8. The heat pump of claim 7, wherein the second orifice check valve is configured to allow substantially unrestricted passage of the portion of expanded refrigerant from the first orifice check valve to the second branch point.

9. The heat pump of claim 7, wherein the second orifice check valve is configured to expand the portion of condensed refrigerant in the cooling mode.

10. The heat pump of claim 9, wherein the first orifice check valve is configured to allow substantially unrestricted passage of the portion of expanded refrigerant from the second orifice check valve to the first branch point.

11. The heat pump of claim 9, wherein the first orifice check valve is configured to inhibit passage of the portion of expanded refrigerant from the second orifice check valve to the first branch point such that the portion of expanded refrigerant is directed to the suction line through the branch line to mix with the refrigerant evaporated in the indoor heat exchanger.

12. The heat pump of claim 7, wherein the power electronics are variable frequency drive (VFD) components.

13. The heat pump of claim 12, wherein the compressor is a variable speed compressor and the VFD components control the speed of the compressor.

14. The heat pump of claim 12, further comprising a supply air fan configured to force air through the indoor heat exchanger, the supply air fan driven by a variable speed motor, wherein the VFD components control the speed of the variable speed motor.

15. The heat pump of claim 12, wherein each of the first and second orifice check valves includes a fixed orifice valve.

16. A method of operating a heat pump, the method comprising:

directing compressed refrigerant from a compressor sequentially to an outdoor heat exchanger to condense the refrigerant, at least one expansion valve to expand the refrigerant, and an indoor heat exchanger to evaporate the refrigerant in a cooling mode;

directing compressed refrigerant from the compressor sequentially to the indoor heat exchanger to condense the refrigerant, the at least one expansion valve to expand the refrigerant, and the outdoor heat exchanger to evaporate the refrigerant in a heating mode;

directing a portion of the condensed refrigerant from a first branch point upstream of the at least one expansion valve toward a heat sink coupled to power electronics;

expanding the portion of condensed refrigerant with a fixed orifice expansion device, the fixed orifice expansion device includes a first orifice check valve configured to expand the portion of condensed refrigerant in the heating mode;

directing the portion of expanded refrigerant to the heat sink;

cooling the heat sink and the power electronics with the expanded portion of the refrigerant;

inhibiting passage of the portion of expanded refrigerant from the first orifice check valve through a second orifice check valve to a second branch point downstream of the at least one expansion valve; and

directing the portion of expanded refrigerant to a suction line between a reversing valve and the compressor and through a branch line that fluidly connects the heat sink to a third branch point on the suction line to mix with refrigerant evaporated by the outdoor heat exchanger.