US 4,167,858 AGranted

Refrigerant deficiency detecting apparatus

AssigneeNippondenso Co., Ltd.

InventorsYasuhumi Kojima, Teiichi Nabeta

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Abstract

In the pipeline of a refrigerator system comprising a compressor, a condenser, an expansion valve and an evaporator, a thermistor adapted to serve as a detector for detecting the dryness of refrigerant is disposed so as to be immersed in the refrigerant at a position where the refrigerant is changed into a homogeneous gas-liquid mixture under the low refrigerant condition. The dryness of the refrigerant is detected by utilizing the fact that while the thermistor is cooled by the refrigerant when its quantity is normal, when its quantity is below normal the refrigerant is changed into a dry gas so that the thermistor is not cooled by the refrigerant and its resistance value is changed. Also a control circuit is provided which is responsive to the signal from the detector, whereby when the dryness of the refrigerant reaches a predetermined value, a signal is generated to render the compressor inoperative. This ensures accurate detection of the shortage of refrigerant and has the effect of preventing failure of the compressor due to the compressor being operated with the insufficient refrigerant.

Claims8

Dependent claims

A refrigerant deficiency detecting apparatus for a refrigerator system including a refrigerant, a compressor, a condensor, a receiver, an expansion valve and an evaporator, said apparatus comprising:

a d.c. electric source;
a temperature responsive resistor element positioned in the refrigerator system between said receiver and evaporator for changing its resistance in response to changes in the cooling effect of said refrigerant;
a current limiting resistor;
normally closed switch means for selectively effecting a series connection between said current limiting resistor and said temperature responsive resistor across said d.c. electric source to provide a temperature responsive d.c. voltage signal at the junction point of said switch means and said temperature responsive resistor;
a comparator circuit connected to said junction point for generating a discrimination signal either when said temperature responsive d.c. signal exceeds a predetermined value or when said normally closed switch means is opened;
a delay circuit connected to said comparator for generating a command signal when said discrimination signal continues to exist for a predetermined time;
and
control means, connected to said delay circuit for rendering said compressor inoperative and for opening said normally closed switch means in response to said command signal.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/835,898Filed 23 Sep 1977
Priority: JP 51-12987127 Oct 1976
Granted: 18 Sep 1979
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G01K 3/005
Thermometers giving results other than momentary value of temperature: circuits arrangements for indicating a predetermined temperature
F25B 49/005
Arrangement or mounting of control or safety devices: of safety devices
G01K 13/02
Thermometers specially adapted for specific purposes: for measuring temperature of moving fluids or granular materials capable of flow
G01N 27/18
Of an electrically-heated body in dependence upon change of temperature: caused by changes in the thermal conductivity of a surrounding material…