Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2000-02-04
2001-08-21
Buiz, Michael Powell (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S211000, C417S300000, C417S302000
Reexamination Certificate
active
06276154
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to fluid flow control devices. More particularly, the present invention relates to a two-step metering device for a variable capacity compressor.
Systems for conditioning air, such as, for example, HVAC systems, air conditioning systems, heat pumps, refrigerators, and freezers may include a variable capacity compressor that is designed to operate at two or more capacities. In this type of conditioning system, the operating capacity of the compressor is varied between a high capacity and a low capacity depending on the operating conditions for the system. Matching the operating capacity of the compressor with the operating conditions can improve the overall efficiency of the conditioning system.
The operating capacity of the compressor may be based on many different operating conditions for the system, including, for example, the conditioning demands of the space being conditioned. The compressor of a refrigerator, for instance, may be operated at full capacity to meet a high demand generated by the introduction of a load of relatively warm items into the cabinet of the refrigerator. The temperature of the cabinet will increase accordingly. This places a greater demand on the cooling system to return the temperature of the cabinet to an acceptable degree. In this situation, the compressor may be run at high capacity to meet the increased demand. When the temperature has been reduced to an acceptable level, the compressor may be operated at a reduced capacity to maintain the desired temperature.
The overall efficiency of a conditioning system is determined by comparing the energy put into the compressor to the amount of heat transferred from the conditioned space. As is known in the art, the greatest efficiency of a conditioning system is achieved when the compressor pressurizes an operating fluid to a predetermined pressure to take advantage of the thermodynamic characteristics of the particular operating fluid. If the compressor is operated at a reduced capacity, the compressor may either pressurize a smaller amount of fluid to the predetermined level or pressurize the same amount of fluid to a reduced level. The most efficient solution is to pressurize a smaller amount of fluid to the predetermined level to take advantage of the thermodynamic characteristics of the operating fluid.
Conditioning systems must also include an expansion valve to reduce the pressure of the operating fluid and allow the operating fluid to expand prior to transferring the heat of the refrigerant and returning to the compressor. There are known expansion valves that are capable of regulating the flow of operating fluid through a conditioning system based on the pressure and/or temperature of the operating fluid. Typically, these valves include a spring-loaded plug disposed adjacent an orifice. The pressurized operating fluid exerts a force on the plug to compress the spring and reveal the orifice. The force of the spring is selected to ensure that the operating fluid has a certain pressure before opening to reveal the orifice. However, these valves are often expensive to manufacture and are often not compatible with the varying demands of a variable capacity compressor.
In light of the foregoing there is a need for a metering device for a variable capacity compressor that is inexpensive and provides a controlled regulation of fluid flow based on the operating capacity of the compressor.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a two-step metering device for a variable capacity compressor. The metering device provides two fluid flow rates that correspond to two operating capacities of the compressor. The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purposes of the invention, as embodied and broadly described herein, the invention is directed to a metering device for controlling the flow of an operating fluid to a variable capacity compressor that is operable at a high capacity and a reduced capacity. The metering device includes a valve defining a fluid flow path for controlling the flow rate of the operating fluid to the compressor. The fluid flow path includes a large orifice configured to allow a flow rate of operating fluid that corresponds to the high capacity of the compressor and a small orifice configured to allow a flow rate of operating fluid that corresponds to the reduced capacity of the compressor. A control is provided to adjust the valve to direct the operating fluid through the large orifice when the compressor is operating at the high capacity and to direct fluid through the small orifice when the compressor is operating at the reduced capacity.
In another aspect, the invention is directed to a system for conditioning air in a space. The system includes a sensor that operates to sense the condition of the space and a compressor that operates to compress an operating fluid at a high capacity and a reduced capacity. A valve is provided for controlling the flow of the operating fluid to the compressor. The valve includes a large orifice configured to allow a flow rate of operating fluid corresponding to the high capacity of the compressor and a small orifice configured to allow a flow rate of operating fluid corresponding to the reduced capacity of the compressor. There is further provided a control operable to run the compressor at one of the first and second operating capacities depending upon the sensed condition of the space. The control is further operable to adjust the valve to direct the operating fluid through the large orifice when the compressor is operating at the high capacity and to direct fluid through the small orifice when the compressor is operating at the reduced capacity.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
REFERENCES:
patent: 2543455 (1951-02-01), Goepfrich
patent: 4009592 (1977-03-01), Boerger
patent: 4425767 (1984-01-01), Barbier
patent: 4429708 (1984-02-01), Strueh
patent: 4459819 (1984-07-01), Hargraves
patent: 4951478 (1990-08-01), McDonald
patent: 5020774 (1991-06-01), Christianson
patent: 5318407 (1994-06-01), Davis
patent: 5364066 (1994-11-01), Dorste et al.
patent: 5405248 (1995-04-01), Alschweig et al.
patent: 5540566 (1996-07-01), Ishizaki et al.
patent: 5715704 (1998-02-01), Cholkeri et al.
Ali Mohammad M
Bristol Compressors, Inc.
Buiz Michael Powell
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
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