Patent
Transport temperature control system having enhanced low ambient heat capacity
| العنوان: | Transport temperature control system having enhanced low ambient heat capacity |
|---|---|
| Patent Number: | 5,669,223 |
| تاريخ النشر: | September 23, 1997 |
| Appl. No: | 08/665,968 |
| Application Filed: | June 21, 1996 |
| مستخلص: | In a transport temperature control system having a cooling and heating mode of operation an apparatus and method are provided for enhancing the heating capacity during the heating mode of operation. A second expansion valve is provided to connect the higher pressure liquid line to the refrigerant circuit downstream of the evaporator. When additional refrigerant is needed in the heating circuit to increase heating capacity, especially during low ambient temperature operating conditions, the second expansion valve is caused to open to admit more refrigerant to the system. After passing through the second expansion valve low pressure gas is passed to the compressor, optimizing compressor efficiency such that an increased amount of hot refrigerant gas is delivered to the evaporator for enhanced heating capacity. |
| Inventors: | Haley, James H. (Eden Prairie, MN); Drake, Gillian M. (Bloomington, MN); Herrig, Doyle G. (Elko, MN) |
| Assignees: | Thermo King Corporation (Minneapolis, MN) |
| Claim: | We claim |
| Claim: | 1. In a transport temperature control system having cooling and heating cycles, a first refrigerant circuit which includes a compressor, condenser, receiver, first expansion valve means, and evaporator, a second refrigerant circuit which includes the compressor and evaporator, and mode selector means having cooling and heating output ports selectively connectable to the first and second refrigerant circuits, respectively, the improvement comprising second expansion valve means having its inlet connected between the receiver and an inlet to said first expansion valve means, an outlet connected between the evaporator and the compressor and sensing means for sensing a superheat condition of the refrigerant at a location between the evaporator and the compressor, such that the opening of said second expansion valve means is controlled according to a predetermined level of the superheat condition. |
| Claim: | 2. The transport temperature control system as recited in claim 1, wherein the predetermined level of the superheat condition is within the range of about 20.degree. F.-40.degree. F. superheat of the refrigerant. |
| Claim: | 3. The transport temperature control system as recited in claim 1, wherein said second expansion valve means is fully closed when the level of the superheat condition is below about 20.degree. F. |
| Claim: | 4. The transport temperature control system as recited in claim 1, wherein said second expansion valve means is fully opened when the level of the superheat condition is above about 40.degree. F. |
| Claim: | 5. The transport temperature control system as recited in claim 1, wherein said sensing means is located a point upstream of the outlet of the second expansion valve. |
| Claim: | 6. The transport temperature control system as recited in claim 3, further comprising a heat exchanger connected between the receiver and said first expansion valve means and an accumulator connected between said evaporator and compressor, the heat exchanger having a first inlet connected to the outlet of the receiver and a first outlet connected to the inlet of said first expansion valve means, a second inlet connected to the outlet of the evaporator and a second outlet connected to an inlet of the accumulator. |
| Claim: | 7. The transport temperature control system as recited in claim 6, wherein the inlet of said second expansion valve means is connected between the first outlet of the heat exchanger and the inlet of said first expansion valve means. |
| Claim: | 8. The transport temperature control means of claim 6, wherein the outlet of said second expansion valve means is connected between the outlet of the evaporator and the second inlet of the heat exchanger. |
| Claim: | 9. The transport temperature control system as recited in claim 8, wherein the sensor bulb of said second expansion valve means is positioned adjacent the outlet of the evaporator. |
| Claim: | 10. The transport temperature control system as recited in claim 1, wherein said sensing means is located a point downstream of the outlet of the second expansion valve. |
| Claim: | 11. The transport temperature control system as recited in claim 1, further comprising a heat exchanger connected between the receiver and said first expansion valve means and an accumulator connected between the evaporator and the compressor, the heat exchanger having a first inlet connected to the outlet of the receiver and a first outlet connected to the inlet of said first expansion valve means, a second inlet connected to the outlet of the evaporator and a second outlet connected to an inlet of the accumulator. |
| Claim: | 12. The transport temperature control system as recited in claim 11, wherein the inlet of said second expansion valve means is connected between the first outlet of the heat exchanger and the inlet of said first expansion valve means. |
| Claim: | 13. The transport temperature control means of claim 11, wherein the outlet of said second expansion valve means is connected between the outlet of the evaporator and the second inlet of the heat exchanger. |
| Claim: | 14. The transport temperature control system as recited in claim 13, wherein said sensing means of said second expansion valve means is positioned adjacent the outlet of the evaporator. |
| Claim: | 15. A method of operating a transport temperature control system having a heating cycle, the system comprising a first refrigerant circuit which includes a compressor, condenser, receiver, first expansion valve and evaporator, and a second refrigerant circuit which includes the compressor and evaporator, mode selector means having cooling and heating output ports selectively connectable to the first and second refrigerant circuits, respectively, and a second expansion valve having its inlet connected between the receiver and an inlet to the first expansion valve and an outlet connected between the evaporator and the compressor, said method comprising the step of |
| Claim: | i. sensing a superheat condition of the refrigerant at a location between the evaporator and the compressor; and |
| Claim: | ii. controlling the opening of the second expansion valve when said sensed superheat condition is outside a predetermined range. |
| Claim: | 16. The method as recited in claim 15, wherein the predetermined range of step ii. is between about 20.degree. F.-40.degree. F. |
| Claim: | 17. The method as recited in claim 16, wherein step ii. comprises fully opening the second expansion valve when the superheat condition is above about 40.degree. F. |
| Claim: | 18. The method as recited in claim 16, wherein step ii. comprises fully closing the second expansion valve when the superheat condition is below about 20.degree. F. |
| Claim: | 19. The method as recited in claim 17, wherein step i. comprises sensing the superheat condition of the refrigerant at a location between the evaporator and the compressor, but downstream of the outlet of the second expansion valve. |
| Claim: | 20. The method as recited in claim 18, wherein step i. comprises sensing the superheat condition of the refrigerant at a location between the evaporator and the compressor, but downstream of the outlet of the second expansion valve. |
| Claim: | 21. The method as recited in claim 17, wherein step i. comprises sensing the superheat condition of the refrigerant at a location between the evaporator and the compressor, but upstream of the outlet of the second expansion valve. |
| Claim: | 22. The method as recited in claim 18, wherein step i. comprises sensing the superheat condition of the refrigerant at a location between the evaporator and the compressor, but upstream of the outlet of the second expansion valve. |
| Current U.S. Class: | 62/160; 62/174; 62/205; 623/244 |
| Current International Class: | F25B 1300 |
| Patent References Cited: | 3370438 February 1968 Hopkinson 4226604 October 1980 Weis 4258553 March 1981 Kelly 4268291 May 1981 Cann 4306420 December 1981 Cann 4324105 April 1982 Cann 4362030 December 1982 Voorhis 4394816 July 1983 Voorhis 4419866 December 1983 Howland 4454725 June 1984 Cann 4720980 January 1988 Howland 4748818 June 1988 Satterness 4903495 February 1990 Howland 4912933 April 1990 Renken 4986084 January 1991 Beckhusen 5056324 October 1991 Haley 5157933 October 1992 Brendel 5168713 December 1992 Howland 5172559 December 1992 Renken 5193353 March 1993 Brendel 5197297 March 1993 Brendel 5415006 May 1995 Renken |
| Primary Examiner: | Tanner, Harry B. |
| رقم الانضمام: | edspgr.05669223 |
| قاعدة البيانات: | USPTO Patent Grants |
| الوصف غير متاح. |