Refrigeration – Refrigeration producer – Compressor-condenser-evaporator circuit
Patent
1995-05-05
1997-07-29
Wayner, William E.
Refrigeration
Refrigeration producer
Compressor-condenser-evaporator circuit
417297, F04B 4900, F25B 100
Patent
active
056512678
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a gas return blocking arrangement for small refrigeration equipments of the type presenting a hermetic compressor mounted in a gas pumping circuit, said arrangement further including a condenser, a capillary tube and an evaporator and being particularly useful in systems in which the pumping of the gas, after a long stop of the compressor, occurs in a condition of pressure gradient. Situations of this type are common in systems presenting reciprocating hermetic compressors.
BACKGROUND OF THE INVENTION
In these systems, when the temperature of the evaporator reaches a predetermined value and the compressor stops, there occurs the migration of the heated fluid, that is present at a high pressure portion of the system, where the condenser is located, towards a low pressure portion of said system, where the evaporator is located. This migration of refrigerant fluid to the evaporator at each stop of the compressor causes loss of refrigerating capacity in the system.
In a known solution, which is useful in refrigeration systems presenting reciprocating hermetic compressors, the gas pumping system receives between the condenser and the capillary tube a blocking valve, which avoids the hot gas from the condenser to reach the evaporator during the long stops of the compressor.
For compressors having a discharge valve designed for a completely sealing operation, the fluid under high pressure remains restricted and retained in the tube portion of the circuit situated downstream said discharge valve.
However, with this sealing, the compressor has to overcome a starting pressure, which is at least equal to the external high pressure existing downstream the discharge valve. As the piston compression stroke is completed with the motor still in the starting condition, the discharge valve will open a respective discharge chamber, before the normal operative condition is reached by the compressor, because the pressure in the cylinder will surpass that pressure existing downstream said discharge valve, at a time inferior to the starting time of the compressor.
In the case of compressors presenting a discharge valve with an impeller, the complete restriction to the passage of gas under high pressure into the inside of the discharge chamber will only exist if, at the stop of the compressor, the piston is at a maximum suction position. In this condition, the new start of said compressor will occur as described above.
In order to compensate the energetic loss in these cases, the new start of the compressor requires the use of a motor presenting a high starting torque. Such increase in the starting torque can also be obtained by incorporating to the system a starting capacitor. Nevertheless, such solutions increase the cost of the product.
The compressors having a discharge valve with an impeller further present another problem, resulting from the stop of the compressor when the piston is at a portion different from that of maximum suction. In this situation, the discharge valve does not seal the discharge chamber completely, thereby allowing leakages of high pressure gas downstream said compressor towards the inside of the latter and, consequently, towards the evaporator, thus causing a loss in the refrigerating capacity of the system.
DISCLOSURE OF THE INVENTION
Thus, it is an object of the present invention to provide a starting arrangement for small refrigeration systems, particularly those using reciprocating hermetic compressors, the arrangement being capable of blocking, during the long stops of the compressor, the passage of heated gas from the compressor to the evaporator and allowing the motor of the compressor to reach an operative condition before the opening pressure of the discharge valve reaches a value corresponding to the high operative pressure of the refrigeration system.
These and other objectives of the present invention are achieved through a starting arrangement for small refrigeration systems, said system presenting: a high pressure region, inc
REFERENCES:
patent: 2074911 (1937-03-01), Hull
patent: 2080288 (1937-05-01), McCormack
patent: 2314591 (1943-03-01), McCormack
patent: 2579429 (1951-12-01), Noe
patent: 3545220 (1970-12-01), Teegarden
patent: 3606588 (1971-09-01), Romerhaus
patent: 4026122 (1977-05-01), Kuhn et al.
Krueger Manfred
Lilie Dietmar Erich Bernhard
Todescat Marcio Luiz
Empresa Brasileira de Compressores S/A - Embraco
Wayner William E.
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