Refrigerant monitoring apparatus and method
First Claim
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 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.
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Accused Products
Abstract
Apparatus for monitoring a refrigerant state in a refrigeration system includes a charge sensor and a controller. The sensor is positioned adjacent to the outlet of an evaporator. The sensor produces a voltage output signal in response to an input signal from the controller. The controller compares the output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state. The sensor is preferably a self-heated thermistor positioned adjacent to flow exiting the evaporator through the outlet. The controller 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 an 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.
136 Citations
58 Claims
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1. Apparatus for monitoring a refrigerant state in a refrigeration system having an evaporator with an outlet, comprising:
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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.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
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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.- View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 52)
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23. A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
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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, 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. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. An air conditioning system comprising:
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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.- View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. Apparatus for monitoring a refrigerant state in a refrigeration system having an evaporator with an outlet, comprising:
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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 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. - View Dependent Claims (46, 47, 48, 49, 50, 51, 53, 54, 55)
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 46.
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50. The method of claim 46, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
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51. Apparatus according to claim 47, wherein said input signal is at least substantially constant.
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53. Apparatus according to claim 46, wherein said controller applies an at least substantially constant current to a circuit interconnecting said controller and said charge sensor.
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54. Apparatus according to claim 46, wherein said input signal is a voltage varied to maintain a constant temperature of said thermistor.
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55. Apparatus according to claim 46, wherein said controller applies an at least substantially constant voltage to a voltage divider circuit to drive said charge sensor.
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56. A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:
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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. - View Dependent Claims (57, 58)
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Specification