Refrigeration – With indicator or tester – Condition sensing
Patent
1993-11-22
1995-03-21
Tanner, Harry B.
Refrigeration
With indicator or tester
Condition sensing
F24F 1100
Patent
active
053985168
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to technology for the high accuracy detection of an insufficiency of refrigerant in airconditioning apparatus suitable for use in automotive cooling equipment and the like.
BACKGROUND ART
In general with air conditioning equipment, a refrigerant sensor is installed in a closed circuit in which refrigerant is circulated, to detect if the amount of refrigerant in the closed circuit is sufficient or insufficient. The present inventors have proposed a refrigerant sensor, as disclosed in pending Japanese Patent Application No. 3-357552 (referred to as prior art in the following) which comprises a sensor body having a refrigerant flow path portion for the passage of refrigerant, provided in a flow path between a condenser and evaporator in a cooling cycle, a refrigerant chamber located in the sensor body above the refrigerant flow path portion and communicated with the interior of the refrigerant flow path portion, and a thermo-sensitive device provided inside the refrigerant chamber for detecting if refrigerant inside the chamber is in a liquid phase condition.
The refrigerant sensor constructed as above is fitted to piping between a receiver tank which holds the liquid phase refrigerant condensed by the airconditioning equipment condenser, and an expansion valve whereby liquid phase refrigerant is expanded and evaporated. With drive to the air conditioning equipment, the compressor comes into operation, and if the refrigerant circulating in the cooling cycle is filled to a sufficient amount, the interior of the refrigerant flow path portion of the refrigerant sensor is filled with the liquid phase refrigerant flowing there through until the surface of the liquid reaches the upper surface of the refrigerant chamber interior.
At this time, since the thermo-sensitive device inside the refrigerant chamber is immersed in the liquid phase refrigerant, there is a significant cooling effect due to the refrigerant, so that the resistance value of components such as a thermistor which make tip the thermo-sensitive device is maintained at a low temperature value. However, if the amount of refrigerant in the cooling cycle is diminished due to refrigerant leakage etc., the liquid level of refrigerant inside the refrigerant chamber is lowered and the thermo-sensitive device exposed above the refrigerant liquid surface. Since the cooling effect of gaseous phase refrigerant is less than that of liquid phase refrigerant, the temperature of the thermo-sensitive device rises, with a consequent change in resistance, causing a change in the current flowing through a warning device, thereby bringing on a light notifying of the refrigerant deficiency.
With the refrigerant sensor according to the above prior art, upward or downward movement of the liquid surface of the refrigerant in the refrigerant chamber is possible even with no change in refrigerant quantity, due to fluctuations in the pressure of refrigerant in the piping caused by a change in compressor rotational speed (with an automotive compressor, due to a change in rotational speed of the engine driving the compressor). As a result, the level of the liquid surface of the refrigerant becomes greater than or less than that of the thermo-sensitive device, immersing or exposing the device, with a consequent change in cooling effect.
Hence, when a refrigerant deficiency is detected with a refrigerant sensor which uses for example a thermistor having a higher resistance at lower temperatures for the thermo-sensitive device, then the characteristics as shown in FIG. 6 are obtained. In this figure, the compressor rotational speed is represented by tile horizontal axis, tile current I in the warning device circuit is represented by the vertical axis, and tile characteristic curves B10, B20, B40, B60, B80, B100, and B120 show the characteristics for respective refrigerant fill percentages ranging from 10, 20, 40, 60, 80, 100 to 120% with 100% being the ideal. The 10 current value in FIG. 6 is the value for the case when the warning d
REFERENCES:
patent: 3059443 (1962-10-01), Garner
patent: 4167858 (1979-09-01), Kojima et al.
patent: 5214918 (1993-06-01), Oguni et al.
Kobayashi Kazumitsu
Kuribara Masaru
Tanner Harry B.
Unisia Jecs Corporation
LandOfFree
Method and apparatus for detecting an insufficiency of refrigera does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for detecting an insufficiency of refrigera, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for detecting an insufficiency of refrigera will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1141834