Control system for a decanter centrifuge

Abstract

A torque sensing device capable of measuring the force exerted by a torque arm on a lever is positioned between the torque arm and the lever. The torque arm is connected to the pinion of a planetary gearbox for rotating the bowl and screw conveyer of a decanter centrifuge at different speeds. The torque sensing device measures the torque between the pinion gear and the planetary gearbox. The sensor can be connected to a controller which can reduce the flow of the liquid/solid mixture to the decanter centrifuge thereby/reducing the torque and avoiding substantial damage to the planetary gearbox.

I claim: 
     
         1 . A torque sensor for measuring the torque applied to a pinion gear of a planetary gearbox for a decanter centrifuge comprising:
 a body having a first stem portion having a first cross-sectional area and a head portion having a second cross-sectional area larger than that of the stem portion; and   a force sensor embedded in the body and having a pair of electrical contacts.   
     
     
         2 . A torque sensor as claimed in  claim 1  wherein the force sensor comprises a thin flexible printed circuit. 
     
     
         3 . A torque sensor as claimed in  claim 2  wherein the force sensor includes a piezoelectric component whose resistance is inversely proportional to an applied force on the body. 
     
     
         4 . A torque sensor as claimed in  claim 1  wherein the head portion has an upper generally planar surface and the force sensor is embedded within the head portion and lies in a plane parallel to the upper generally planar surface of the head. 
     
     
         5 . A method of controlling the liquid/solid mixture flow rate to a decanter centrifuge, the decanter centrifuge including a planetary gearbox having a central pinion gear, a torque arm fixed to the pinion gear and a pivoted lever arm connected at one end to an over center spring mechanism and engaging the torque arm at a second portion comprising:
 positioning a torque sensor between the torque arm fixed to the pinion gear and the second portion of the lever arm;   measuring the torque force applied to the lever arm; and   varying the flow rate of the liquid solid mixture to the decanter centrifuge in response to the force applied to the lever arm.   
     
     
         6 . The method of  claim 5  including varying the flow rate of the liquid/solid mixture by varying the speed of a variable speed pump which pumps the liquid/solid mixture to the decanter centrifuge. 
     
     
         7 . The method of  claim 5  including varying the flow rate of the liquid/solid mixture by controlling an adjustable valve. 
     
     
         8 . The method of  claim 5  including the terminating the flow of the liquid/solid mixture to the decanter centrifuge, at a predetermined maximum torque load. 
     
     
         9 . The method of  claim 5  including the step of establishing a range of acceptable torque force levels applied to the lever arm and varying the flow rate of the solid/liquid mixture so that the torque force level is maintained within the predetermined range. 
     
     
         10 . The method of  claim 5  further comprising the step of providing a remote monitor including a display device for displaying the measured torque force and varying the flow rate of the liquid/solid mixture in response to force measurements displayed on the monitor. 
     
     
         11 . A method of controlling the liquid/solid mixture flow rate to a decanter centrifuge, the decanter centrifuge including a planetary gearbox having a central pinion gear, a torque arm fixed to the pinion gear and a pivoted lever arm connected at one end to a support and engaging the torque arm at a second portion comprising:
 positioning a torque sensor between the torque arm fixed to the pinion gear and the second portion of the lever arm;   measuring the torque force applied to the lever arm; and   varying the flow rate of the liquid solid mixture to the decanter centrifuge in response to the force applied to the lever arm.   
     
     
         12 . The method of  claim 11  including varying the flow rate of the liquid/solid mixture by varying the speed of a variable speed pump which pumps the liquid/solid mixture to the decanter centrifuge. 
     
     
         13 . The method of  claim 11  including varying the flow rate of the liquid/solid mixture by controlling an adjustable valve. 
     
     
         14 . The method of  claim 11  including the terminating the flow of the liquid/solid mixture to the decanter centrifuge. 
     
     
         15 . The method of  claim 11  including the step of establishing a range of acceptable torque force levels applied to the lever arm and varying the flow rate of the solid/liquid mixture so that the torque force level is maintained within the predetermined range.