US5457965A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low refrigerant charge detection system
Assignee: Visteon Global Technologies Inc
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Filing: 1994-04-11
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Granted: 1995-10-17
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Expires: 2014-04-11
Abstract
Abstract An apparatus for detecting is disclosed for detecting a low level of refrigerant circulating through a motor vehicle refrigerant circuit. The apparatus comprises an electronic logic module, and a pressure transducer and a thermistor preferably located in the refrigerant circuit between the compressor and the evaporator. The pressure transducer generates a signal indicative of the refrigerant pressure, from which the module derives a saturation temperature of the refrigerant. The saturation temperature is compared with the measured temperature to determine if a superheat condition exists indicative of low refrigerant charge exists. When the refrigerant remains at a predetermined level of superheating, the compressor clutch is disengaged to interrupt circulation through the refrigerant circuit. In an alternative embodiment, a pair of thermistors are respectively situated proximate an inlet and an outlet of an evaporator, and the module interrupts circulation when the outlet thermistor indicates a temperature more than a predetermined amount greater than the inlet thermistor. In a third embodiment, a pressure switch in the refrigerant circuit generates a signal when a predetermined pressure is reached, and the module interrupts circulation if the temperature of the medium at the predetermined pressure corresponds to a superheat condition.
Inventors
- 👤 John H. Blair
- 👤 Norman H. Dolinski
- 👤 Gerhard A. Dage
- 👤 George E. Peck
- 👤 Manfred Koberstein
- 👤 Robert W. Matteson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:40
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; F; F25; F25B; F25B49/00; F25B49/005; G01F23/14; F25B2500/00; F25B2500/24
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
135 words
An apparatus for detecting a low level of a medium circulating through a motor vehicle refrigerant circuit including a compressor, a condenser and an evaporator, the apparatus comprising: a pressure transducer for generating a signal indicative of the pressure of the medium in the refrigerant circuit; means for measuring the temperature of the medium; and an electronic logic module in communication with the pressure transducer and the means for measuring the temperature of the medium, the module accepting a plurality of inputs from the pressure transducer and the means for measuring the temperature and interrupting operation of the compressor when the medium remains at a predetermined level of superheating; the pressure transducer and the means for measuring the temperature of the medium being located in the refrigerant circuit substantially between the compressor and the condenser.
Claim 2
Independent Claim
135 words
An apparatus for detecting a low level of a medium circulating through a motor vehicle refrigerant circuit including a compressor, a condenser and an evaporator, the apparatus comprising: a pressure transducer for generating a signal indicative of the pressure of the medium in the refrigerant circuit; means for measuring the temperature of the medium; and an electronic logic module in communication with the pressure transducer and the means for measuring the temperature of the medium, the module accepting a plurality of inputs from the pressure transducer and the means for measuring the temperature and interrupting operation of the compressor when the medium remains at a predetermined level of superheating; the pressure transducer and the means for measuring the temperature of the medium being located in the refrigerant circuit substantially between the compressor and the condenser.
Claim 3
Dependent Claim
28 words
The apparatus of claim 1 wherein the electronic logic module interrupts electrical power to a clutch of the compressor when the medium reaches the predetermined level of superheating.
Claim 4
Dependent Claim
18 words
The apparatus of claim 1 wherein the means for measuring the temperature of the medium comprises a thermistor.
Claim 5
Dependent Claim
22 words
The apparatus of claim 1 wherein the electronic logic module includes a look-up table having the predetermined level of superheating stored therein.
Claim 6
Independent Claim
93 words
An apparatus for detecting a low level of a medium circulating through a motor vehicle refrigerant circuit, the apparatus comprising: a switch situated in the refrigerant circuit and generating an output signal when a predetermined pressure is reached; means for measuring the temperature of the medium; and an electronic logic module in electrical communication with the switch and the means for measuring the temperature of the medium, the module being adapted to interrupt circulation through the refrigerant circuit if the temperature of the medium at the predetermined pressure corresponds to a superheat condition.
Claim 7
Independent Claim
93 words
An apparatus for detecting a low level of a medium circulating through a motor vehicle refrigerant circuit, the apparatus comprising: a switch situated in the refrigerant circuit and generating an output signal when a predetermined pressure is reached; means for measuring the temperature of the medium; and an electronic logic module in electrical communication with the switch and the means for measuring the temperature of the medium, the module being adapted to interrupt circulation through the refrigerant circuit if the temperature of the medium at the predetermined pressure corresponds to a superheat condition.
Claim 8
Dependent Claim
13 words
The apparatus of claim 5 wherein the switch comprises a clutch cycling switch.
Claim 9
Dependent Claim
19 words
The apparatus of claim 6 wherein the clutch cycling switch is located on an accumulator of the refrigerant circuit.
Claim 10
Dependent Claim
13 words
The apparatus of claim 5 wherein the switch comprises a dual function switch.
Claim 11
Dependent Claim
23 words
The apparatus of claim 8 wherein the dual function switch is located on a high side of a compressor of the refrigerant circuit.
Claim 12
Dependent Claim
23 words
The apparatus of claim 5 wherein the means for measuring the temperature of the medium comprises a thermistor situated in the refrigerant circuit.
Claim 13
Dependent Claim
25 words
The apparatus of claim 17 wherein the refrigerant circuit includes a compressor, and the thermistor is situated on a low pressure side of the compressor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-10-16 | 1999-04-17 | 1999-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-10-16 | 2003-04-17 | 2003-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-10-16 | 2007-04-17 | 2007-10-17 | $7700.00 | Window Closed / Lapsed |