Lubricant supply system and method for controlling gearbox lubrication

Abstract

A lubricant supply system for a gearbox includes a lubricant flow circuit having, in fluid flow sequence: a variable-flow rate first pump; an lubricant cooler; and a gearbox. The system also includes: a first temperature sensor for sensing a temperature of lubricant circulating within the lubricant flow circuit; a pressure sensor for sensing a pressure of lubricant circulating within the lubricant flow circuit; and a controller operably connected to the pressure and temperature sensors and to the first pump. The controller is operable to control flow of the pump in response to the sensed temperature and to the sensed pressure.

1 . A lubricant supply system, comprising:
 a lubricant flow circuit comprising, in fluid flow sequence:
 a variable flow rate first pump; 
 a lubricant cooler; and 
 a gearbox; 
   a first temperature sensor for sensing a temperature of lubricant circulating within the lubricant flow circuit;   a pressure sensor for sensing a pressure of lubricant circulating within the lubricant flow circuit; and   a controller configured to be operably connected to the pressure and temperature sensors and to the first pump, the controller operable to control flow of the first pump in response to the sensed temperature and to the sensed pressure.   
     
     
         2 . The system of  claim 1  further comprising a second pump mechanically driven by the gearbox and coupled in the lubricant flow circuit in parallel with the first pump. 
     
     
         3 . The system of  claim 1  wherein the first temperature sensor is disposed in the lubricant flow circuit downstream of the gearbox. 
     
     
         4 . The system of  claim 1  further comprising a sump disposed in the lubricant flow circuit between the gearbox and the first pump. 
     
     
         5 . The system of  claim 4  comprising a second temperature sensor disposed in the sump for sensing a temperature of lubricant in the sump, wherein die controller is operably connected to the second temperature sensor, the controller operable to control the flow of the first pump in response to the sensed temperature of the lubricant in the sump. 
     
     
         6 . The system of  claim 1  wherein the controller is programmed with proportional-integral -derivative logic. 
     
     
         7 . The system of  claim 1  wherein the pressure sensor is disposed in the lubricant flow circuit downstream of the first pump. 
     
     
         8 . The system of  claim 1  wherein the controller is programmed with a lubricant temperature setpoint and a lubricant pressure setpoint, and the controller is operable to control the flow of the first pump in response to the sensed temperature and to the sensed pressure in comparison to the lubricant temperature setpoint and the lubricant pressure setpoint, respectively. 
     
     
         9 . The system of  claim 8  wherein the controller is programmed to limit a maximum flow rate of lubricant through the lubricant flow circuit referencing the lubricant pressure setpoint, and to limit a minimum flow rate of lubricant through the lubricant flow circuit referencing the lubricant temperature setpoint. 
     
     
         10 . A method for controlling gearbox lubrication, comprising:
 circulating lubricant at a flow rate through a lubricant flow circuit comprising a variable flow rate first pump, a lubricant cooler, and a gearbox;   sensing a first temperature of the lubricant, and varying the flow rate with reference to a lubricant temperature setpoint; and   sensing a pressure of the lubricant, and varying the flow rate with reference to a lubricant pressure setpoint.   
     
     
         11 . The method of  claim 10  further comprising using a second pump disposed in parallel with the first pump and mechanically driven by the gearbox to circulate lubricant through the lubricant flow circuit. 
     
     
         12 . The method of  claim 10  wherein the first temperature is sensed in the lubricant flow circuit downstream of the gearbox. 
     
     
         13 . The method of  claim 10  further comprising circulating the lubricant through a sump disposed in the lubricant flow circuit between the gearbox and the first pump. 
     
     
         14 . The method of  claim 13  further comprising sensing a second temperature of lubricant in the sump; wherein the lubricant flow rate is controlled with reference to a higher of the first and second temperatures. 
     
     
         15 . The method of  claim 10  further comprising using proportional-integral-derivative logic to control the lubricant flow rate. 
     
     
         16 . The method of  claim 10  wherein the lubricant pressure is sensed in the lubricant flow circuit downstream of die first pump. 
     
     
         17 . The method of  claim 10  further comprising determining a maximum lubricant flow rate referencing the lubricant pressure setpoint, and determining a minimum flow rate referencing the lubricant temperature setpoint. 
     
     
         18 . The method of  claim 17  further comprising preferentially controlling the lubricant flow rate referencing either the lubricant pressure setpoint or the lubricant temperature setpoint depending on a predetermined priority. 
     
     
         19 . The method of  claim 10  wherein the lubricant is circulated at a flow rate sufficiently low so that the lubricant pressure does not exceed the lubricant pressure setpoint.