CA2410872A1 - Refrigerant monitoring apparatus and method - Google Patents
Refrigerant monitoring apparatus and method Download PDFInfo
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- CA2410872A1 CA2410872A1 CA002410872A CA2410872A CA2410872A1 CA 2410872 A1 CA2410872 A1 CA 2410872A1 CA 002410872 A CA002410872 A CA 002410872A CA 2410872 A CA2410872 A CA 2410872A CA 2410872 A1 CA2410872 A1 CA 2410872A1
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- output signal
- controller
- sensor
- charge
- set point
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- 239000003507 refrigerant Substances 0.000 title claims abstract 69
- 238000012544 monitoring process Methods 0.000 title claims abstract 6
- 238000000034 method Methods 0.000 title claims 26
- 238000001514 detection method Methods 0.000 claims abstract 21
- 238000005057 refrigeration Methods 0.000 claims abstract 14
- 238000004378 air conditioning Methods 0.000 claims abstract 4
- 241000287181 Sturnus vulgaris Species 0.000 claims 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/005—Arrangement or mounting of control or safety devices of safety devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
- F25B2700/195—Pressures of the condenser
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2117—Temperatures of an evaporator
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/022—Compressor control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/027—Condenser control arrangements
Abstract
Apparatus for monitoring a refrigerant state in a refrigeration system includes a charge sensor (28) and a controller (30). The sensor (28) is positioned adjacent to the outlet of an evaporator (2). The sensor (28) produces a voltage output signal in response to an input signal from the controller (30). The controller (30) compares the output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state. The sensor (28) is preferably a self-heated thermistor positioned adjacent to flow exiting the evaporator (2) through the outlet. The controller (30) preferably compares the output signal to a set point at preset intervals and computes an average for a predetermined time duration. This helps to avoid false readings due to transitory conditions. The apparatus may be used in various types of refrigeration systems but is contemplated to be used primarily in mobile air conditioning systems in order to detect a reduced refrigerant charge in such systems. In such applications, the input signal is preferably and at least substantially constant voltage applied to a voltage divider circuit. Input from elements in addition to the charge sensor may be used to enhance the accuracy of detection.
Claims (103)
1. Apparatus for monitoring a refrigerant state in a refrigeration system having an evaporator with an outlet, comprising:
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state.
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state.
2. Apparatus according to claim 1, wherein said charge sensor is a self-heated thermistor.
3. Apparatus according to claim 2, wherein said thermistor is positioned adjacent to flow exiting the evaporator through the outlet.
4. Apparatus according to claim 3, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
5. Apparatus according to claim 2, wherein said controller compares said output signal to said set point at preset intervals and ,computes an average for a predetermined time duration.
6. Apparatus according to claim 1, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
7. Apparatus according to claim 2, wherein said controller applies an at least substantially constant current to a circuit interconnecting said controller and said charge sensor.
8. Apparatus according to claim 2, wherein said input signal is a voltage varied to maintain a constant temperature of said thermistor.
9. Apparatus according to claim 2, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
10. Apparatus for detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
11. Apparatus according to claim 10, wherein said charge sensor is a self-heated thermistor.
12. Apparatus according to claim 11, wherein said thermistor is positioned adjacent to flow exiting the evaporator through the outlet.
13. Apparatus according to claim 12, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
14. Apparatus according to claim 11, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
15. Apparatus according to claim 10, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
16. Apparatus according to claim 12, wherein said thermistor is positioned about 90° to vertical.
17. Apparatus according to claim 10, wherein said controller compares said output signal to a first predetermined set point to determine whether a low charge condition exists and to a second predetermined set point to determine whether a very low charge condition exists.
18. Apparatus according to claim 10, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
19. Apparatus according to claim 11, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
20. Apparatus according to claim 14, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
21. Apparatus according to claim 15, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
22. Apparatus according to claim 11, wherein said input signal is at least substantially constant.
23. Apparatus according to claim 22, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
24. A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
positioning a charge sensor adjacent to the outlet of the evaporator;
electrically connecting said sensor to a controller;
sending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal;
sending said output signal from said sensor to said controller;
in said controller, comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
positioning a charge sensor adjacent to the outlet of the evaporator;
electrically connecting said sensor to a controller;
sending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal;
sending said output signal from said sensor to said controller;
in said controller, comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
25. The method of claim 24, wherein said charge sensor is a thermistor.
26. The method of claim 25, wherein positioning said charge sensor comprises positioning said thermistor adjacent to flow exiting the evaporator through the outlet.
27. The method of claim 26, wherein comparing said output signal comprises comparing said output signal to said set point at preset intervals and computing an average for a predetermined time duration.
28. The method of claim 25, wherein comparing said output signal comprises comparing said output signal to said set point at preset intervals and computing an average for a predetermined time duration.
29. The method of claim 24, wherein comparing said output signal comprises comparing said output signal to said set point at preset intervals and computing an average for a predetermined time duration.
30. The method of claim 24, wherein said controller compares said output signal to a first predetermined set point to determine whether a low charge condition exists and to a second predetermined set point to determine whether a very low charge condition exists.
31. The method of claim 25, wherein said controller receives a pressure signal from a transducer positioned in a high pressure side of the refrigeration system and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
32. The method of claim 28, wherein said controller receives a pressure signal from a transducer positioned in a high pressure side of the refrigeration system and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
33. The method of claim 25, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
34. An air conditioning system comprising:
a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator; and apparatus for detecting a reduced refrigerant charge in said circuit, said apparatus including:
a charge sensor positioned adjacent to said outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator; and apparatus for detecting a reduced refrigerant charge in said circuit, said apparatus including:
a charge sensor positioned adjacent to said outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
35. A system according to claim 34, wherein said charge sensor is a self-heated thermistor.
36. A system according to claim 35, wherein said thermistor is positioned adjacent to flow exiting the evaporator through the outlet.
37. A system according to claim 36, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
38. A system according to claim 35, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
39. A system according to claim 34, wherein said controller compares said output signal to said set point at preset intervals and computes an average for a predetermined time duration.
40. A system according to claim 34, wherein said controller compares said output signal to a first predetermined set point to determine whether a low charge condition exists and to a second predetermined set point to determine whether a very low charge condition exists.
41. A system according to claim 34, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
42. A system according to claim 35, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
43. A system according to claim 38, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
44. A system according to claim 39, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
45. Apparatus according to claim 35, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
46. Apparatus for monitoring a refrigerant state in a refrigeration system having an evaporator with an outlet, comprising:
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said controller applying, as said input signal, an at least substantially constant voyage to a voltage divider circuit to drive said sensor, said sensor producing a voltage output signal in response co said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state.
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said controller applying, as said input signal, an at least substantially constant voyage to a voltage divider circuit to drive said sensor, said sensor producing a voltage output signal in response co said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state.
47. Apparatus according to claim 46, wherein said charge sensor is a self-heated thermistor.
48. Apparatus according to claim 47, wherein said thermistor is positioned adjacent to flow exiting the evaporator through the outlet.
49. Apparatus according to claim 48, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
50. Apparatus according to claim 47, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
51. Apparatus according to claim 46, wherein said controller compares said output signal to said set point at preset intervals, stares a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
52. Apparatus for detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said controller applying, as said input signal, an at least substantially constant voltage to a voltage divider circuit to drive said sensor; said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said controller applying, as said input signal, an at least substantially constant voltage to a voltage divider circuit to drive said sensor; said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
53. Apparatus according to claim 52, wherein said charge sensor is a self-heated thermistor.
54. Apparatus according to claim 53, wherein said thermistor is positioned adjacent to flow exiting the evaporator through the outlet.
55. Apparatus according to claim 54, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
56. Apparatus according to claim 53, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
57. Apparatus according to claim 52, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
58. Apparatus according to claim 54, wherein said thermistor is positioned about 90° to vertical.
59. Apparatus according to claim 52, wherein said controller compares said output signal to a first predetermined set point to determine whether a low charge condition exists and to a second predetermined set point to determine whether a very low charge condition exists.
60. Apparatus according co claim 52, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge,
61. Apparatus according to claim 53, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
62. Apparatus according to claim 56, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
63. Apparatus according to claim 57, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
64. A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising;
positioning a charge sensor adjacent to the outlet of the evaporator;
electrically connecting said sensor to a controller;
ending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal, including applying an at least substantially constant voltage to a voltage divider circuit to drive said sensor;
sending said output signal from said sensor to said controller;
in said controller, comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
positioning a charge sensor adjacent to the outlet of the evaporator;
electrically connecting said sensor to a controller;
ending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal, including applying an at least substantially constant voltage to a voltage divider circuit to drive said sensor;
sending said output signal from said sensor to said controller;
in said controller, comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
65. The method of claim 64, wherein said charge sensor is a thermistor.
66. The method of claim 65, wherein positioning said charge sensor comprises positioning said thermistor adjacent to flow exiting the evaporator through the outlet.
67. The method of claim 66, wherein comparing said output signal comprises comparing said output signal to said set point at preset intervals and storing a history of comparisons for a predetermined time duration.
68. The method of claim 65, wherein comparing said output signal comprises comparing said output signal to said sec point at preset intervals and storing a history of comparisons for a predetermined time duration.
69. The method of claim 64, wherein comparing said output signal comprises comparing said output signal to said set point at preset intervals and storing a history of comparisons for a predetermined time duration.
70. The method of claim 64, wherein said controller compares said output signal to a first predetermined set point to determine whether a low charge condition exists and to a second predetermined set point to determine whether a very low charge condition exists.
71. The method of claim 65, wherein said controller receives a pressure signal from a transducer positioned in a high pressure side of the refrigeration system and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
72. The method of claim 68, wherein said controller receives a pressure signal from a transducer positioned in a high pressure side of the refrigeration system and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
73. An air conditioning system comprising:
a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator; and apparatus for detecting a reduced refrigerant charge in said circuit, said apparatus including:
a charge sensor positioned adjacent to said outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said controller applying, as said input signal, an at least substantially constant voltage to a voltage divider circuit to drive said sensor, said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator; and apparatus for detecting a reduced refrigerant charge in said circuit, said apparatus including:
a charge sensor positioned adjacent to said outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said controller applying, as said input signal, an at least substantially constant voltage to a voltage divider circuit to drive said sensor, said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.
74. A system according to claim 73, wherein said charge sensor is a self-heated thermistor.
75. A system according to claim 74, wherein said thermistor is positioned adjacent to flow exiting the evaporator through the outlet.
76. A system according to claim 75, wherein said controller compares said output signal to said see point at preset intervals, scores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
77. A system according to claim 74, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
78. A system according to claim 73, wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.
79. A system according to claim 73, wherein said controller compares said output signal to a first predetermined set point to determine whether a low charge condition exists and to a second predetermined set point to determine whether a very low charge condition exists.
80. A system according to claim 73, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
81. A system according to claim, 74, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
82. A system according to claim 77, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge,
83. A system according to claim 78, which further comprises a high pressure side pressure transducer, and in which said controller receives a pressure signal from said transducer and uses said pressure signal, to calculate a correction factor to shift said voltage output signal to improve reliability of detection of a reduced refrigerant charge.
84. Apparatus for monitoring a refrigerant state in a refrigeration system having an evaporator with an outlet, comprising:
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state;
wherein paid controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history .
a charge sensor positioned adjacent to the outlet of the evaporator; and a controller electrically connected to said sensor to provide an input signal thereto;
said sensor producing a voltage output signal in response to said input signal; and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state;
wherein paid controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history .
85. Apparatus according to claim 84, wherein said controller applies an at least substantially constant current to a circuit interconnecting said controller and said charge sensor.
86. Apparatus according to claim 84, wherein said input signal is a voltage varied to maintain a constant temperature of said thermistor.
97. Apparatus according to claim 84, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
88. Apparatus according to claim 84, wherein said controller determines whether a reduced refrigerant charge exists, and said predetermined refrigerant state is indicative of a reduced refrigerant charge.
89. Apparatus according to claim 88, wherein said input signal is at least substantially constant.
90. Apparatus according to claim 89, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
91. Apparatus according to claim 88, wherein said controller computes an average of said output signal for said predetermined time duration.
92. Apparatus according to claim 88, wherein said controller determines a percentage of output signal readings that are less than said set point during said predetermined time duration.
93. An air conditioning system comprising:
a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator; and apparatus for monitoring a refrigerant state as set forth in claim 88.
a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator; and apparatus for monitoring a refrigerant state as set forth in claim 88.
94.~The method of claim 93, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
95. A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
positioning a charge sensor adjacent to the outlet of the evaporator;
electrically connecting said sensor to a controller;
sending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal;
sending said output signal from said sensor to said controller;
in said controller, comparing at preset intervals said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge, storing a history of comparisons for a predetermined time duration, and making a determination of a refrigerant charge level based on said history.
positioning a charge sensor adjacent to the outlet of the evaporator;
electrically connecting said sensor to a controller;
sending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal;
sending said output signal from said sensor to said controller;
in said controller, comparing at preset intervals said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge, storing a history of comparisons for a predetermined time duration, and making a determination of a refrigerant charge level based on said history.
96. The method of claim 95, wherein making said determination comprises computing an average of output signal readings for said predetermined time duration.
97. The method of claim 95, wherein making said determination comprises determining a percentage of output signal readings that are less than said set point during said predetermined time duration.
98. Apparatus according to claim 51, wherein said controller computes an average of said output signal for said predetermined time duration.
99. Apparatus according to claim 51, wherein said controller determines a percentage of output signal readings that are less than said set point during said predetermined time duration.
100. Apparatus according to claim 57, wherein said controller computes an average of said output signal for said predetermined time duration,
101. Apparatus according to claim 57, wherein said controller determines a percentage of output signal readings that are less than said set point during said predetermined time duration.
102. The method of claim 69, wherein said controller computes an average of output signal readings in said history.
103. The method of claim 69, wherein said controller determines a percentage of output signal readings in said history that are less than said set point
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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US09/584,204 | 2000-05-31 | ||
US09/584,204 US6293114B1 (en) | 2000-05-31 | 2000-05-31 | Refrigerant monitoring apparatus and method |
PCT/US2001/040809 WO2001092794A1 (en) | 2000-05-31 | 2001-05-24 | Refrigerant monitoring apparatus and method |
Publications (2)
Publication Number | Publication Date |
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CA2410872A1 true CA2410872A1 (en) | 2001-12-06 |
CA2410872C CA2410872C (en) | 2012-03-13 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA2410872A Expired - Fee Related CA2410872C (en) | 2000-05-31 | 2001-05-24 | Refrigerant monitoring apparatus and method |
Country Status (5)
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US (1) | US6293114B1 (en) |
EP (1) | EP1290385A1 (en) |
AU (2) | AU2001275502B2 (en) |
CA (1) | CA2410872C (en) |
WO (1) | WO2001092794A1 (en) |
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-
2000
- 2000-05-31 US US09/584,204 patent/US6293114B1/en not_active Expired - Lifetime
-
2001
- 2001-05-24 AU AU2001275502A patent/AU2001275502B2/en not_active Ceased
- 2001-05-24 EP EP01942223A patent/EP1290385A1/en not_active Withdrawn
- 2001-05-24 WO PCT/US2001/040809 patent/WO2001092794A1/en active IP Right Grant
- 2001-05-24 AU AU7550201A patent/AU7550201A/en active Pending
- 2001-05-24 CA CA2410872A patent/CA2410872C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
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AU2001275502B2 (en) | 2004-07-29 |
WO2001092794A1 (en) | 2001-12-06 |
EP1290385A1 (en) | 2003-03-12 |
AU7550201A (en) | 2001-12-11 |
US6293114B1 (en) | 2001-09-25 |
CA2410872C (en) | 2012-03-13 |
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