Control method for controlling the gas flow in a compressor

Abstract

A control method for controlling the gas flow by a compressor in which a volume is expanded during an intake stroke and the intaken volume of gas is compressed and taken out through a non return valve ( 6 ) for outflow and/or an operable outlet valve ( 3 ) during an evacuation stroke, and in which the compressor has a controllable inlet valve ( 2 ) that is pneumatically, hydraulically or electromagnetically operable and that is opened and closed upon basis of a signal from a control system. The inlet valve ( 2 ) is kept closed during at least a part of an intake stroke.

1 . A control method for controlling the gas flow by a compressor in which a volume is expanded during an intake stroke and the introduced volume of gas is compressed and taken out through a non return valve ( 6 ) for outflow and/or an operable outlet valve ( 3 ) during an evacuation stroke, and in which the compressor has a controllable inlet valve ( 2 ) that is pneumatically, hydraulically or electromagnetically operable and that is opened and closed upon basis of a signal from a control system, characterized in that the inlet valve ( 2 ) is kept closed during at least a part of an intake stroke.  
   
   
       2 . A control method according to  claim 1 , characterized in that the inlet valve ( 2 ) is kept closed during the whole intake stroke.  
   
   
       3 . A control method according to  claim 1 , characterized in that the frequency of cycles with closed intake stroke is varied between 0% and 100% of the number of revolutions per minute in order to, at the given number of revolutions per minute, deliver the amount of the compressed gas required for the moment.  
   
   
       4 . A control method according to  claim 3 , characterized in that, between each cycle or each continuous series of cycles with closed intake strokes, an equal amount of revolutions are performed.  
   
   
       5 . A control method according to  claim 1 , characterized in that the inlet valve ( 2 ) is closed upon transition, or after the transition, from intake stroke to evacuation stroke.  
   
   
       6 . A control method according to  claim 1 , characterized in that the inlet of the compressor ( 1 ), besides the controllable inlet valve ( 2 ), comprises a non return valve ( 13 ) for inflow, and that the conduit for supply of gas to the latter is throttled down or closed by means of a closure member ( 14 ) arranged by or upstream the non return valve, by controlling the gas pressure in a tank ( 8 ) associated to the compressor.  
   
   
       7 . A control method according to  claim 6 , characterized in that the closure member ( 14 ) is a controllable valve, which is opened and closed upon basis of a signal from the control system.  
   
   
       8 . A control method according to  claim 1 , characterized in that the outlet of the compressor ( 1 ), apart from a non return valve ( 6 ) for outflow, comprises a controllable outlet valve ( 3 ) which is pneumatically, hydraulically or electro-magnetically operated, and which opens and closes upon basis of a signal from the control system.  
   
   
       9 . A control method according to  claim 1 , characterized in that the outlet valve ( 3 ) is opened as there is a pressure balance between the gas to be evacuated and the gas on the opposite side of the outlet valve ( 3 ), the latter being controlled by means of a sensor ( 18 ) that registers the cylinder pressure that is compared to the pressure in the tank registered by another sensor ( 9 ).  
   
   
       10 . A control method according to  claim 1 , characterized in that a conduit ( 7 ) that extends between the compressor ( 1 ) and the tank ( 8 ) fulfills the need of pressurized gas between the compressor and the equipment that will use the pressurized gas.  
   
   
       11 . A control system, characterized in that it comprises a computer program adapted for executing the control method according to  claim 1 .  
   
   
       12 . A control method according to  claim 2 , characterized in that the frequency of cycles with closed intake stroke is varied between 0% and 100% of the number of revolutions per minute in order to, at the given number of revolutions per minute, deliver the amount of the compressed gas required for the moment.  
   
   
       13 . A control method according to  claim 12 , characterized in that, between each cycle or each continuous series of cycles with closed intake strokes, an equal amount of revolutions are performed.