Determining the amount of working fluid in a refrigeration or he

Details Determining the amount of working fluid in a refrigeration or he Determining the amount of working fluid in a refrigeration or he

1995-06-26

1998-03-10

Tanner, Harry B.

Refrigeration

With indicator or tester

Condition sensing

F25B 4902

Patent

active

057248222

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to the determination of the amount of working fluid in a compressor-operated refrigeration or heat pump system.
More particularly, the invention relates to a method for determining the existing amount of working fluid in a compressor-operated refrigeration or heat pump system, in which method the existing values of at least two variable quantities, consisting of the temperature or the pressure at different preselected places in the system, are sensed at a moment when the system is in operation and the sensed values of said quantities or at least one value of at least one other variable quantity, derived from said sensed values, are/is utilized for determining an approximate value of the magnitude of the amount of working fluid based upon a previously established relationship between the magnitude of the existing amount of working fluid in the system and the value or values, respectively, of the utilized quantity or quantities.
A method of the above kind is previously known through U.S. Pat. No. 5,009,076. However, a disadvantage of this known method is the inaccuracy in the possible determination of the amount of working fluid in the system.
The invention therefore has for its object to provide an improved method of the kind above defined, which makes it possible to achieve a substantially increased accuracy in the determination of the existing amount of working fluid in the system.
For this purpose, the method proposed according to the invention is primarily characterized in that at least two different preliminary approximate values of the magnitude of the amount of working fluid are determined while utilizing values of at least partially different variable quantities and that a resultant approximate value is then determined based upon said preliminary values.
Preferably, one of the preliminary values may be selected as the resultant value. In this case, different preliminary values may be selected as the resultant value within different regions for the magnitude of one of the preliminary values.
Alternatively, the resultant value may be determined through a weighting procedure in which different weights are assigned to the preliminary values.
A still further increased accuracy in the determination of the magnitude of the amount of working fluid may be obtained if each preliminary approximate value is determined based upon a relationship between the magnitude of the amount of working fluid and the value or values, respectively, of the utilized quantity or quantities, selected in view of the existing conditions of at least one of the two external media. By way of example, one condition of an external medium which may deserve to be taken into account when selecting said relationship, may be the temperature of said medium. Another possible condition is the moisture content of the medium. If the external medium consists of a flowing medium, said relationship should also be selected in view of the existing flow rate of said medium.
The invention also relates to an arrangement for determining the existing amount of working fluid in a compressor-operated refrigeration or heat pump system.
Below the invention will be further described with reference to the accompanying drawings, in which:
FIG. 1 shows a refrigeration system for use in an air-conditioning plant of a car and an arrangement according to the invention for determining the existing amount of working fluid in said system, while
FIGS. 2 and 3 are diagrams showing curves which illustrate experimentally measured relationships between the amount of working fluid in said refrigeration system and different variable quantities, depending thereon, which may be utilized in the arrangement according to the invention.
The refrigeration system shown in FIG. 1 and generally designated 10 is designed as a closed system which contains a condenser 11, a fixed restriction 12, formed by a capillary tube, an evaporator 13, a liquid separator 14 and a compressor 15. The system contains a working fluid which, when the system is in operation, ci

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patent: 4220010 (1980-09-01), Mueller et al.
patent: 4265091 (1981-05-01), Kobayashi
patent: 5009074 (1991-04-01), Goubeaux et al.
patent: 5009076 (1991-04-01), Winslow
patent: 5150584 (1992-09-01), Tomasov et al.
patent: 5152152 (1992-10-01), Brickner et al.
patent: 5241833 (1993-09-01), Ohkoshi

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