Refrigeration – With indicator or tester – Operatively correlated with automatic control
Reexamination Certificate
2000-07-18
2001-11-20
Tanner, Harry B. (Department: 3744)
Refrigeration
With indicator or tester
Operatively correlated with automatic control
C062S129000
Reexamination Certificate
active
06318097
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for monitoring the refrigerant level in an air conditioner, and more specifically, to a method for monitoring the refrigerant level in an air conditioner having a compressor with a high pressure refrigerant circuit and a low pressure refrigerant circuit.
2. Description of the Related Art
DE 44 01 415 C1 describes a generic method for monitoring the refrigerant level in an air conditioner, the air conditioner having a compressor subdividing the refrigerant circuit into a high-pressure side and a low-pressure side. The pressure and the temperature are measured on the high-pressure side at time intervals, an assigned temperature is determined using the measured pressure with the aid of a refrigerant-specific function, and a refrigerant undercooling value Uw which can be evaluated as a measure of the refrigerant level is determined by subtracting the measured temperature from the assigned one. At least during prescribable operating phases of the air conditioner, use is made for the purpose of assessing the refrigerant level of a maximum value Mw which is set at the start of these operating phases to the last determined undercooling value Uw and is set in the course of this operating phase to a respectively newly determined undercooling value when the latter is greater than the maximum value Mw present at the corresponding instant.
In the case of this type of method for monitoring the refrigerant level in an air conditioner, it is disadvantageous that given a low outside temperature in the range below 15° C. the externally controlled compressor is driven at low par, with the result that the measured relative pressure on the high-pressure side is low. No result capable of further use is obtained in this range for the undercooling value determined therefrom.
The present invention is aimed at one or more of the problems identified above.
BRIEF SUMMARY OF THE INVENTION
The object of the invention is to improve a method for monitoring the refrigerant level in an air conditioner such that the refrigerant level can be optimally monitored even in the case of low outside temperatures.
According to the invention, the object is achieved by the features of claim
1
. Advantageous refinements and developments of the subject matter of the invention are characterized by the features of the subclaims.
A substantial advantage of these refinements resides in that monitoring of the refrigerant level can be performed in the range of low outside temperatures.
REFERENCES:
patent: 5239865 (1993-08-01), Salzer et al.
patent: 5398516 (1995-03-01), Kuribara et al.
patent: 5647222 (1997-07-01), Sarakinis
patent: 5987903 (1999-11-01), Bathla
patent: 44 01 415 C 1 (1994-01-01), None
Calcaterra Mark P.
Daimler-Chrysler AG
Tanner Harry B.
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