US 4,765,150 AGranted

Continuously variable capacity refrigeration system

AssigneeMargaux Controls, Inc.

InventorJacob P. Persem

Life of this patent

Estimating the term…

Loading patent…

Abstract

A refrigeration compressor system using a reciprocating compressor with continuously variable capacity. The speed of the compressor can be varied substantially continuously over predefined range of speeds. A controller for the compressor monitors one or more physical parameters indicative of the temperature of the application being refrigerated, such as the temperature itself and/or the pressure in the compressor's refrigerant suction line. Using a predefined algorithm, the controller adjusts the speed of said compressor so as to keep said monitored parameter within a predefined target range. In a preferred embodiment, the compressor is an open direct drive compressor. The compressor's motor has a substantially continuous range of useable operating speeds which varies by a ratio of more than two to one. Furthermore, the controller has a plurality of control strategies for adjusting the speed of the compressor's motor, including one for adjusting the motor's speed in accordance with difference between the measured temperature and a specified target temperature, one for adjusting the motor's speed in accordance with difference between the pressure in the compressor's refrigerant suction line and a specified target temperature, and one for adjusting the motor's speed in accordance with both the temperature and suction pressure.

Claims11

Dependent claims

A single stage compressor system for use in a refrigeration system having one or more refrigerator cases wherein goods are stored said refrigeration system including condensing means for condensing compressed refrigerant from said compressor system, evaporating means for expanding the refrigerant in said condensing means and thereby removing heat from said refrigerator cases, and compressor suction line means for directing expanded refrigerant from said evaporating means to said compressor system, said compressor system comprising:

a reciprocating compressor coupled to a three phase drive motor in an open direct drive arrangement, said motor having a capacity of at least five horsepower;
inverter means for driving said motor at a speed specified by a motor speed signal, wherein said speed can be varied substantially continuously over a predefined range of speeds;
load sensing means for detecting at least one physical parameter indicative of the load on the refrigeration system selected from the set consisting of the temperature in at least one of said refrigerator cases, and the pressure in said compressor suction line means, and for generating a load differential signal corresponding to the difference between said detected physical parameter and a specified target value;
control means, responsive to said load differential signal, for adjusting the capacity of the refrigeration system by adjusting the speed of said motor within said predefined range of speeds, including software means for establishing an initial speed value and for periodically adjusting said speed value so as to minimize said load differential signal, and means for generating a motor speed signal corresponding to said speed value;
wherein said control means adjusts the capacity of said refrigeration system within a substantially continuous range.

2 more elements

A method of controlling the capacity of a single stage compressor system for use in a refrigeration system having one or more refrigerator cases wherein goods are stored, said refrigeration system including condensing means for condensing compressed refrigerant from said compressor system, evaporating means for expanding the refrigerant in said condensing means and thereby removing heat from said refrigerator cases, and compressor suction line means for directing expanded refrigerant from said evaporating means to said compressor system, the steps of the method comprising:

providing a reciprocating compressor coupled to a three phase drive motor in an open direct drive arrangement, said motor having a capacity of at least five horsepower, and inverter means for driving said motor at a speed specified by a motor speed signal, wherein said speed can be varied substantially continuously over a predefined range of speeds;
detecting at least one physical parameter indicative of the load on the refrigeration system selected from the set consisting of the temperature in at least one of said refrigerator cases, and the pressure in said compressor suction line;
generating an error signal .DELTA.S corresponding to the difference between said detected physical parameter and a specified target value;
and
periodically adjusting the capacity of the refrigeration system by adjusting the speed of said motor within said predefined range of speeds, including the steps of establishing an initial speed value, periodically adjusting said speed value so as to minimize said error signal, and generating a motor speed signal corresponding to said speed value;
wherein the capacity of said refrigeration system is automatically adjusted within a substantially continuous range so as to match the load on said refrigeration system.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/012,578Filed 9 Feb 1987
Granted: 23 Aug 1988
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

F25B 49/025
For compression type machines, plants or systems: motor control arrangements
F04B 49/065
Control using electricity: and making use of computers
F04B 49/20
Control , e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided…:…
F16D 3/68
Comprising elastic elements arranged between substantially-radial walls of both coupling parts: the elements being made of rubber or similar material