Method and apparatus to regulate oil pressure via controllable piston cooling jets

Abstract

A method of regulating oil pressure within an engine assembly is provided. The engine assembly includes an oil pump configured to provide oil to an oil system of the engine assembly; a piston cooling jet configured to direct a jet of oil from the oil system towards a piston of an engine; and an electronic control valve configured to control the flow of oil to the piston cooling jet. The method includes operating the electronic control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or engine running speed; and regulating the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or engine running speed, by operating the electronic control valve.

2 . The method of claim  1 , wherein the electronic control valve is operated to provide a flow rate of oil below the threshold flow rate to the piston cooling jet when the pressure of oil within the oil system is being regulated. 
     
     
         3 . The method of claim  1 , wherein the oil pump is a fixed oil pump configured such that the pressure of oil provided by the oil pump varies according to the engine running speed. 
     
     
         4 . The method of claim  1 , wherein the electronic control valve is a variable control valve configured to allow the flow rate of oil to the piston cooling jet to be selectively varied. 
     
     
         5 . The method of claim  1 , further comprising determining the pressure of oil within the oil system. 
     
     
         6 . The method of claim  1 , further comprising:
 controlling the operation of the electronic control valve such that the pressure of oil within the oil system is maintained at or below a first threshold pressure level.   
     
     
         7 . The method of  claim 6 , further comprising:
 controlling the operation of the electronic control valve such that the pressure of oil within the oil system is not reduced below a second threshold pressure level.   
     
     
         8 . The method of claim  1 , further comprising:
 controlling the operation of the electronic control valve to maintain the pressure of oil within the oil system at a particular value.   
     
     
         9 . An engine assembly, comprising:
 an oil pump configured to provide oil to an oil system;   a piston cooling jet, configured to direct a jet of oil from the oil system towards a piston of an engine;   an electronic control valve configured to control the flow of oil to the piston cooling jet; and   a controller configured to:
 operate the electronic control valve to provide a flow rate of oil above a threshold flow rate to the piston cooling jet when the engine assembly is operating above a threshold power output or threshold engine running speed; and 
 regulate the pressure of oil within the oil system when the engine assembly is operating below the threshold power output or threshold engine running speed, by operating the electronic control valve. 
   
     
     
         10 . The engine assembly of  claim 9 , wherein the oil pump is a fixed oil pump configured such that the pressure of oil provided by the oil pump varies according to a running speed of the engine assembly. 
     
     
         11 . The engine assembly of  claim 9 , wherein the electronic control valve is a variable flow control valve operable to control the flow rate of oil passing through the electronic control valve. 
     
     
         12 . The engine assembly of  claim 11 , wherein the engine assembly further comprises a pressure sensor configured to determine the pressure of oil within the oil system. 
     
     
         13 . The engine assembly of  claim 12 , wherein the controller is configured to control the operation of the electronic control valve in order to maintain the pressure of oil within the oil system at or below a first threshold pressure level. 
     
     
         14 . The engine assembly of  claim 13 , wherein the controller is configured to control the operation of the electronic control valve in order to maintain the pressure of oil within the oil system at or above a second threshold pressure level. 
     
     
         15 . A method for regulating oil pressure within an engine assembly, comprising:
 operating an electronic control valve in a fully open position to provide oil to a piston cooling jet when the engine assembly is operating above a threshold engine running speed or engine load, the piston cooling jet configured to jet oil from an oil system towards a piston of an engine, the oil system including an oil pump; and   decreasing a degree of valve opening of the electronic control valve to enable oil flow through the valve within a target pressure range to the piston cooling jet when the engine assembly is operating below the threshold engine running speed or load.   
     
     
         16 . The method of  claim 15 , further comprising, subsequent to decreasing the degree of valve opening, increasing a degree of valve opening in response to determining an increase in engine speed or engine load. 
     
     
         17 . The method of  claim 15 , where the oil pump is a fixed geometry oil pump and where an output of the fixed geometry oil pump corresponds to the engine running speed. 
     
     
         18 . The method of  claim 15 , further comprising, operating the electronic control valve in a fully closed position. 
     
     
         19 . The method of  claim 15 , further comprising, prior to decreasing the degree of valve opening, determining the target pressure range based on engine speed and engine load. 
     
     
         20 . The method of  claim 15 , where the electronic control valve is continuously adjustable in a plurality of open positions between the fully open position and a fully closed position.