Refrigeration – Automatic control – Withdrawing or adding refrigerant from or to normally closed...
Reexamination Certificate
2002-05-14
2003-10-07
Jones, Melvin (Department: 3744)
Refrigeration
Automatic control
Withdrawing or adding refrigerant from or to normally closed...
C062S115000
Reexamination Certificate
active
06629421
ABSTRACT:
BACKGROUND OF THE INVENTION
Refrigeration units used in refrigeration engineering contain a compressor that compresses the refrigerant vapor. The vapor is then cooled and condensed as a result of contact with a “cold source”. With the use of the expansion valve the pressure of the condensed fluid is then decreased down to a pressure low enough to enable the vaporization of the fluid, which absorbs heat from the cooling matter by contacting a so-called, “hot source”. Thereafter, the vaporized gas is returned to the compressor. This type of unit should be controlled to avoid interruption of service. Firstly, if the amount of heat available at the cold source is low, large quantities of liquid refrigerant may be returned to the compressor resulting in damage to the compressor and energy loss. Secondly, if the amount of heat that is available at the hot source is excessive, the rate of liquid flow arriving at the evaporator may not be high enough to maintain the hot source at a desired low temperature level. The excessive amount of heat from the hot source can damage the motor of the compressor.
In the U.S. Pat. No. 4,631,926 by Goldstein et all disclosed the refrigerating unit where the refrigerant flow was controlled by a solenoid valve that was placed between a condenser and an evaporator. The solenoid valve was operating in an “on-off” regimen and was providing liquid refrigerant in a pulse feed manner from the condenser to the evaporator. The liquid refrigerant was boiled out in the evaporator at a low pressure and temperature in a step-wise range with a number of steps, changing that pressure and temperature depending on the final temperature of the refrigerant, which was an average value from several differential pressure and temperature relays. The unit was able to operate with a minimum condensing pressure. The main disadvantage of the disclosed system was that the solenoid valve operates in a heavy-duty regimen due to the large number of circuit switches. Furthermore, the feed device for controlling the refrigerant flow was not reliable due to the use of pressure relay to govern the solenoid valve. In addition, the system for controlling the refrigerant flow was too complicated due to many pressure and temperature relays. Moreover, there was a problem connected with repulsion of the evaporator due to the low pressure of the steam refrigerant caused by a low ambient temperature of the air or water, which was cooling down the condenser.
In conclusion, a need existed for improving the construction and reliability of a refrigeration feed device.
SUMMARY OF THE INVENTION
According to the present invention the self-governing device for a pulse feeding process consists of a housing with an inlet and outlet, a cover, a bushing with two slots on its external surface and with two openings on each slot, positioned in the housing, a piston moving in the bushing and having separate left and right chambers with two openings each, respectively. When the movable piston is placed in the left position, the opening in the left chamber coincides with the corresponding opening in the bushing, and through the corresponding slot connects to the inlet through which the refrigerant flows from a condenser with a higher pressure. At the same time, the opening in the right chamber coincides with the corresponding opening in the bushing and through the corresponding slot connects to the outlet through which the refrigerant flows to an evaporator with lower internal pressure. Due to the difference in the refrigerant's pressure the piston moves to the right. When the movable piston reaches the right position, the opening in the left chamber coincides with the corresponding opening in the bushing and through the corresponding slot connects to the outlet through which the refrigerant flows to an evaporator with a lower internal pressure. At the same time, the opening in the right chamber coincides with the corresponding opening in the bushing and trough the corresponding slot connects to the inlet through which the refrigerant flows from the condenser with a higher pressure, and so on.
A refrigeration unit with a self-governing device for a pulse feeding process is comprised of a compressor, a condenser, an evaporator, the self-governing device for a pulse feeding process that is connected to the condenser and to said evaporator, respectively, a thermostat to control the temperature of the refrigerant vapor in a suction line, which is electrically connected to the compressor. When the temperature of the refrigerant vapor in the suction line decreases, in time, the thermostat turns the compressor's motor off and stops the cooling process. When the temperature of the refrigerant vapor in the suction line is increased, the thermostat turns the compressor's motor on and the cooling process will continue.
A refrigeration unit with the self-governing device for a pulse feeding process enables it to change the amount of refrigerant during the cooling process. It is comprised of a compressor, a condenser connected to at least two solenoid valves, a self-governing device for the pulse feeding process that is connected to solenoid valves and an evaporator, at least two thermostats that control the temperature of the refrigerant vapor in the suction line, and at least one of the thermostats is electrically connected to the corresponding solenoid valve and another thermostat is electrically connected to the compressor. When the temperature of the refrigerant vapor in said suction line decreases, in time the thermostat turns the corresponding solenoid valve off to reduce the refrigerant flow to the evaporator. If the temperature of the refrigerant vapor continues to fall and reaches the value established in a set point adjustment, the corresponding thermostat turns the motor of the compressor off and stops the cooling process. When the temperature of the refrigerant vapor in said suction line is increased, the thermostat turns the compressor's motor on and the cooling process will continue.
A refrigeration unit with the self-governing device for a pulse feeding process has a gas defrost and is comprised of a compressor, a condenser, a self-governing device for the pulse feeding process that is connected to the solenoid valve that is placed between the compressor and the condenser, an evaporator, a thermostat that is electrically connected to the compressor to control the temperature of the refrigerant vapor in the suction line, a solenoid valve that is placed on the line that connects the discharge line of the compressor with the evaporator and is electrically connected to the timer, a pressure controller with set point adjustment that is connected to the discharge line of the compressor, and is electrically connected to the solenoid valve that is placed on said line. When the temperature of the refrigerant vapor in the suction line decreases, in time the thermostat turns the compressor's motor off and stops the cooling process. When the temperature of refrigerant vapor in the suction line is increased, the thermostat turns the compressor's motor on and the cooling process will continue. The timer regulates the gas defrost process of the evaporator. This process starts at the time that is set on the timer, the solenoid valve that is placed between the condenser and the evaporator is closed and the circuit of the solenoid valve that is placed on the line and is connected to the discharge line of the compressor with the evaporator is locked; but the solenoid valve is opened if the pressure of refrigerant vapor in the discharge line is equal to or greater than the pressure that is set on the controller. The gas defrost process stops when a set-point time on the timer has elapsed. The solenoid valve that is placed between the compressor and the condenser is open, the circuit of the solenoid valve that is placed on the line connecting the discharge line of the compressor with the evaporator is open and this solenoid valve is closed.
REFERENCES:
patent: 4274376 (1981-06-01), Tsiang et al.
Khaytin Boris
Levitin Mikhail
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