Compressor control mechanism and method

Abstract

The present invention is a mechanical refrigeration system and method of operation thereof including a compressor, a condenser, an expansion valve an evaporator, a hot gas bypass line and a hot gas valve. A control regulates the operation of the compressor and the hot gas valve and, upon determining that the compressor is to be shut off, first opens the hot gas valve for a predetermined time period to reduce any pressure differential between the high and low pressure sides of the compressor. This pressure reduction providing for reducing or eliminating any destructive compressor movement that would otherwise occur at shut down as the momentum of the moving parts of the compressor operate against a pressure differential. A similar method can be used to avoid such unwanted movement at start-up of the compressor.

1 . A refrigeration system comprising: 
 a compressor fluidly connected to a high pressure line extending between a high pressure outlet side of the compressor and a condenser, the condenser in fluid communication with an expansion valve for regulating a flow of condensed and cooled refrigerant to an evaporator and the evaporator fluidly connect to a low pressure inlet side of the compressor, and a bypass line having a hot gas valve therein for directing refrigerant from the high pressure outlet side of the compressor to the inlet side of the compressor, and a control mechanism for operating the expansion valve, the compressor and the hot gas valve for closing the expansion valve and at substantially the same time opening the hot gas valve for a first predetermined period of time prior to a desired shut off of the compressor.    
     
     
         2 . The system as defined in    claim 1    and the first predetermined period of time elapsing substantially at the time of shut off of the compressor whereupon the hot gas valve is closed.  
     
     
         3 . The system as defined in    claim 1    and the first predetermined period of time elapsing after the turn off of the compressor whereupon the hot gas valve is closed.  
     
     
         4 . A refrigeration system comprising: 
 a compressor fluidly connected to a high pressure line extending between a high pressure outlet side of the compressor and a condenser, the condenser in fluid communication with an expansion valve for regulating a flow of condensed and cooled refrigerant to an evaporator and the evaporator fluidly connect to a low pressure inlet side of the compressor, and a bypass line having a hot gas valve therein for directing refrigerant from the high pressure outlet side of the compressor to the inlet side of the compressor, and a control mechanism for operating the expansion valve, the compressor and the hot gas valve for closing the expansion valve and at substantially the same time opening the hot gas valve for a first predetermined period of time prior to a desired shut off of the compressor and the control closing the hot gas valve after the lapse of a second predetermined period of time following the shut off of the compressor.