Danfoss A/s

Jakob S Jakobsen

Leif Skovvang Nielsen

Zbigniew R Huelle

Robert M McCulloch

The invention relates to a valve assembly for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a movable wall of an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The pressure exerted by the vapor phase of the medium provides a bias in a valve opening direction which is directly related to the temperature of the liquid phase and is opposed by a spring bias in the valve closing direction. A heat transfer element such as a heating resistor in the liquid phase is heated or allowed to cool in a controlled manner by an external control unit. A temperature responsive sensor element in the liquid phase of the medium is part of a feedback system for the control unit which allows a selected temperature to be maintained in the chamber which results in a desired constant pressure in a valve opening direction to be maintained in a chamber. A control unit has an evaporator parameter input branch and a second input branch for the feedback temperature sensing element. The control unit has an output for heating the heating resistor in the expansible chamber and a summating section for varying the relative effects of the input branches on the output.

Valve for liquid injection into a refrigerant evaporator

The invention relates to a valve unit for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a movable wall of an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The pressure exerted by the vapor phase of the medium provides a bias in a valve closing direction which is directly related to the temperature of the liquid phase. A heat transfer element such as a heating resistor in the liquid phase is heated or allowed to cool in a controlled manner by an external control unit. A temperature responsive sensor element in the liquid phase of the medium is part of a feedback system for the control unit which allows a selected temperature to be maintained in the chamber which results in a desired constant pressure in a valve closing direction to be maintained in the chamber.

Valve for refrigeration plant

The invention relates to a valve assembly for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a reference pressure generator having an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The pressure exerted by the vapor phase of the medium provides a bias for controlling the valve and is directly related to the temperature of the liquid phase. A heat transfer element such as a heating resistor in the liquid phase is heated or allowed to cool in a controlled manner by an external control unit. A temperature responsive sensor element in the liquid phase of the medium is part of a feedback system for the control unit which allows a selected temperature to be maintained in the chamber which results in a desired constant pressure in a valve opening direction to be maintained in a chamber. A control circuit has an evaporator parameter input branch and a second input branch for the feedback temperature sensing element. The control unit has an output for heating the heating resistor in the expansible chamber and a summating section for varying the relative effects of the input branches on the output.

Regulating circuit for the valve of a refrigeration plant

A speed regulator for a guide and follower motor assembly. A guide pulse frequency generator driven by a guide motor drives a frequency converter which drives a follower motor. The frequency converter includes a frequency regulator with a negative feed back which includes a frequency divider. Adjusting and setting circuits for the frequency divider include an up/down counter for operating the frequency divider, a resetting operation of the counter to provide a frequency indicating value for its output, an adjustable pulse generator for driving the counter, an add/subtract circuit, and a comparator responsive to the add/subtract circuit and the counter to control the pulse generator.

Arrangement for guiding the rotary speed of one or more follower motors

The invention relates to a controlled heating system for maintaining a predetermined or set temperature in a medium of small dimensions which may be a gas, liquid or solid. A single element such as a power transistor functions as a heat transfer device for supplying heat to the medium and as a heat sensing device for sensing temperature changes in the medium which can be fed back and serve as control data for supplying make-up heat to maintain a predetermined temperature. The transistor supplies heat via heat dissipation in its collector-emitter path and senses heat changes via its base-emitter voltage which varies in response to temperature changes in the medium. The controlled heating may be applied to a valve assembly for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a movable wall of an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The transistor serves as a heat transfer element and as a temperature responsive sensor element.

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Sonderborg, Denmark

Jakob S Jakobsen