A Fan Drive Assembly

Abstract

A fan drive assembly for a vehicle, which can provide reverse fan flow. The assembly has a fan, where separate forward and reverse clutches are coupled to the fan. The reverse clutch has a greater torque capacity than the forward clutch, such that when the reverse clutch is applied, the forward clutch is made to slip, allowing for the reverse rotation and flow of the fan.

1 . A fan drive assembly for a vehicle comprising:
 a fan;   a forward clutch arranged to rotate the fan in a forward direction, the forward clutch comprising a viscous clutch; and   a reverse clutch arranged to rotate the fan in a reverse direction, the reverse clutch comprising an on/off clutch which is engaged when reverse fan rotation is desired, wherein the reverse clutch is selected such that the torque capacity of an engaged reverse clutch is greater than the torque capacity of the forward clutch when the reverse clutch is engaged, to rotate the fan in a reverse direction.   
     
     
         2 . The fan drive assembly of  claim 1 , wherein the fan drive assembly is configured such that the forward clutch is partly disengaged when the reverse clutch is engaged. 
     
     
         3 . The fan drive assembly of  claim 1 , wherein the torque capacity of the forward clutch is adjustable, wherein the forward clutch is controlled such that, when the reverse clutch is engaged, the torque capacity of the forward clutch is adjusted to be less than the torque capacity of the engaged reverse clutch. 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . The fan drive assembly of  claim 1 , wherein the reverse clutch is a dry clutch, preferably an electromagnetic clutch. 
     
     
         7 . The fan drive assembly of  claim 1 , wherein the forward clutch is coupled to a forward drive, preferably using a forward fan belt. 
     
     
         8 . The fan drive assembly of  claim 1 , wherein the reverse clutch is coupled to a reverse drive, preferably using a reverse fan belt. 
     
     
         9 . The fan drive assembly of  claim 1 , wherein the forward drive and the reverse drive are provided as opposite output shafts from a bevel gearbox. 
     
     
         10 . The fan drive assembly of  claim 1 , wherein the forward and reverse clutches are located at opposite sides of the fan. 
     
     
         11 . The fan drive assembly of  claim 1 , wherein the forward and reverse clutches can be located at the same side of the fan. 
     
     
         12 . A vehicle, preferably an agricultural vehicle, comprising a fan drive assembly as claimed in  claim 1 . 
     
     
         13 . The vehicle of  claim 12 , wherein the vehicle further comprises an Engine Control Unit (ECU), wherein the ECU is operable to control the reverse clutch of the fan drive assembly to perform a reverse fan flow of the fan drive assembly. 
     
     
         14 . The vehicle of  claim 13 , wherein the ECU is arranged to receive a fan clean command from an operator, and responsive to said fan clean command, the ECU operates the fan drive assembly in a reverse direction to clean the fan and any associated components, of debris.