Arrangement and Method for a Compressed Air System

Abstract

The invention includes an arrangement for a compressed air system including an air compressor arranged to generate compressed air for the compressed air system, an air dryer arranged to dry the generated compressed air and an arrangement for unloading the air compressor in certain conditions. The arrangement for unloading includes a control unit arranged to send a control signal to a valve, an air line between the valve and the air compressor, with the control unit being arranged to activate the control signal for unloading the air compressor in the event of at least one predetermined operating state of the air compressor. A method for a compressed air system is also disclosed. Improved unloading of an air compressor can be obtained, which takes place in the event of certain predetermined operating states, such as for example, when an engine speed exceeds a particular limit value.

1 . An arrangement for a compressed air system, comprising
 an air compressor arranged to generate compressed air for the compressed air system,   an air dryer arranged to dry generated compressed air, and   means for unloading the air compressor in certain conditions, wherein the unloading means comprises a control unit arranged to send a control signal to a valve, and an air line between the valve and air compressor, with the control unit being arranged to activate the control signal for unloading the air compressor in the event of at least one predetermined operating state of the air compressor.   
   
   
       2 . The arrangement as claimed in  claim 1 , wherein the arrangement is adapted to be driven by an engine arranged in a vehicle. 
   
   
       3 . The arrangement as claimed in  claim 2 , wherein the predetermined operating state corresponds to at least one of the following conditions being fulfilled:
 i) a speed of the engine exceeds a first predetermined limit value,   ii) a rate of increase in the engine speed exceeds a second predetermined limit value,   iii) a torque of the engine exceeds a third predetermined limit value.   
   
   
       4 . The arrangement as claimed in  claim 3 , wherein the control unit is arranged to activate the unloading only when a system pressure in the compressed air system exceeds a predetermined minimum value corresponding to the system pressure being sufficiently high to ensure a correct braking function of the vehicle and/or sufficient lifting force in an air suspension system of the vehicle. 
   
   
       5 . The arrangement as claimed in  claim 1 , wherein the control unit is arranged to control the unloading with a hysteresis. 
   
   
       6 . The arrangement as claimed in  claim 1 , the control unit is connected to a data link by means of which information about relevant data is transferred for determining whether the at least one predetermined operating state applies. 
   
   
       7 . The arrangement as claimed in  claim 1 , the valve is arranged to be connected directly to the air dryer. 
   
   
       8 . A method for a compressed air system, comprising:
 generating compressed air for compressed air system by means of an air compressor,   drying the generated compressed air by means of an air dryer, and   unloading the air compressor in certain conditions,   generation of a control signal from a control unit to a valve for activating an air flow via the valve, an air line and onward to the air compressor, for unloading the air compressor in the event of at least one predetermined operating state of the air compressor.   
   
   
       9 . The method as claimed in  claim 8 , comprising operating the air compressor by means of an engine adapted for a motor vehicle. 
   
   
       10 . The method as claimed in  claim 9 , comprising initiating unloading of the air compressor when an operating state that corresponds to at least one of the following conditions is fulfilled:
 i) a speed of the engine exceeds a first predetermined limit value,   ii) a rate of increase in the engine speed exceeds a second predetermined limit value,   iii) a torque of the engine exceeds a third predetermined limit value.   
   
   
       11 . The method as claimed in  claim 10 , comprising initiating unloading when a system pressure in the compressed air system exceeds a predetermined minimum value corresponding to the system pressure being sufficiently high to ensure a correct braking function of the vehicle and/or lifting force in an air suspension system of the vehicle. 
   
   
       12 . The method as claimed in  claim 11 , comprising controlling the unloading of the compressor with a hysteresis. 
   
   
       13 . The method as claimed in  claim 9 , comprising transmitting to the control unit information about relevant data for determining whether the at least one predetermined operating state applies.