Parker-hannifin Corporation

Roy M Yabuki

Richard L Kenyon

Virender Jain

Sandra L Harper

Chester D Campbell

Alan Matthies

Michael E Nolan

Ashok G Zopey

Roger G Riefler

Derek Y Kamemoto

Jain Virender

Apparatus for detecting low charge of a working fluid in a heat transfer system of the type having a fluid circuit comprising a compressor for pressurizing working fluid received from an evaporator, a condenser and condenser fan for cooling the working fluid received from the compressor, and an expansion device for controlling flow of the working fluid between the condenser and the evaporator, the apparatus comprising: a working fluid state sensor operative in response to a control signal and disposed in the fluid circuit on the outlet side of the evaporator to produce a working fluid state signal; and a control circuit for providing the control signal to the sensor and for controlling operation of the heat transfer system based on a comparison of the working fluid state signal with a state set point; the control circuit detecting a low charge condition of the working fluid when the state signal indicates the working fluid superheat exceeds a first predetermined threshold over a first predetermined time with the expansion device in a fully open condition.

Method and apparatus for detecting low refrigerant charge

Apparatus for detecting working fluid state in a heat transfer system of the type having an evaporator and an expansion valve for controlling mass flow of the working fluid to the evaporator, comprises a first sensor disposed in the working fluid on the outlet side of the evaporator; the first sensor producing a first signal related to the working fluid state; a second sensor disposed in the working fluid on the inlet side of the evaporator; the second sensor producing a second signal related to a pressure dependent characteristic of the working fluid; and a control circuit for receiving the first and second signals and determining the working fluid state based on a ratio of the first and second signals.

Apparatus and method for mass flow control of a working fluid

A heat transfer system includes a high side pressure sensor in the form of a temperature dependent resistance in heat exchange with the system working fluid to locally heat the fluid in response to a control signal. Control means are provided for applying the control signal to the resistance and detecting a minimum thermal resistance between the thermistor and the working fluid.

Apparatus and method for detecting characteristics of a working fluid

A mass flow control apparatus and method for use in combination with a heat transfer system having a compressor, condenser, expansion valve, evaporator and working fluid in a fluid circuit. The mass flow is controlled using a quality sensor for the working fluid exiting the evaporator, and a high side pressure sensor. A control circuit is provided that monitors the quality sensor and the high side pressure sensor, and controls operation of the compressor, condenser fan and valve in response thereto. A flow reduction mode is used to reduce high side pressure at the valve inlet without excessive compressor cycling by changing the quality sensor set point when the high side pressure exceeds the condenser fan turn-on pressure but is less than the compressor disengage pressure.

An expansion valve (10) for heat transfer systems such as an air conditioning system, includes a control element (20) for controlling the flow rate of working fluid through the valve. The control element has a stem member (28) and movable member (42) movable on the stem member. Openings (38) to an internal passage (30) in the stem member are regulated by positioning the movable member to achieve regulated flow rate of refrigerant material through the valve. The movable member of the control element is moved by a plunger (24) of a proportional solenoid (22). The proportional solenoid has a magnetic flux circuit including a low permeance isolation tube (62) surrounding the plunger, which enables removal of the coil (76) and frame (78) of the solenoid from the valve. The solenoid further includes a variable permeance flux washer (69) the flux through which varies with plunger position, which is disposed from a gap (82) which provides an area of magnetic saturation. The proportional solenoid produces force/displacement characteristics which enable precise control of the control element and accurate regulation of the refrigerant flow rate through the valve.

Expansion valve control element for air conditioning system

Expansion valve for air conditioning system with proportional solenoid

A mass flow control apparatus and method for use in combination with a heat transfer system having a compressor, condenser, expansion valve, evaporator and working fluid in a s fluid circuit. The mass flow is controlled using a quality sensor for the working fluid exiting the evaporator, and a high side pressure sensor. A control circuit is provided that monitors the quality sensor and the high side pressure sensor, and controls operation of the compressor, condenser fan and valve in response thereto. A flow reduction mode is used to reduce high side pressure at the valve inlet without excessive compressor cycling by changing the quality sensor setpoint when the high side pressure exceeds the condenser fan turn-on pressure but is less than the compressor disengage pressure.

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Los Angeles, CA, United States of America

Roy M Yabuki