Engine fuel pump drive system

Abstract

A fuel pump drive mechanism may include a fuel pump rocker arm and a fulcrum member. The fuel pump rocker arm may have a first end defining a cam engagement region and a second end defining a fuel pump engagement region. The fulcrum member may be engaged with the rocker arm and may be displaceable between first and second positions. The fulcrum member may engage the rocker arm at a first location between the first and second ends when in the first position and may engage the rocker arm at a second location between the first location and the second end when in the second position. The rocker arm may provide a first pump stroke for the lifter when the fulcrum member is in the first position and a second pump stroke for the lifter less than the first pump stroke when the fulcrum member is in the second position.

1 . A fuel pump drive mechanism comprising:
 a fuel pump rocker arm having a first end defining a cam lobe engagement region and a second end defining a fuel pump lifter engagement region; and   a fulcrum member engaged with the rocker arm and displaceable between first and second positions, the fulcrum member engaging the rocker arm at a first location between the first and second ends when in the first position and engaging the rocker arm at a second location between the first location and the second end when in the second position, the rocker arm providing a first pump stroke for the lifter when the fulcrum member is in the first position and a second pump stroke for the lifter less than the first pump stroke when the fulcrum member is in the second position.   
     
     
         2 . The fuel pump drive mechanism of  claim 1 , wherein the fulcrum member includes first and second pivot regions, the fulcrum member being rotatable from the first position where the first pivot region abuts the rocker arm at the first location to the second position where the second pivot region abuts the rocker arm at the second location. 
     
     
         3 . The fuel pump drive mechanism of  claim 1 , further comprising an actuation mechanism engaged with the fulcrum member and displacing the fulcrum member between the first and second positions. 
     
     
         4 . The fuel pump drive mechanism of  claim 3 , wherein the actuation mechanism includes an electrical solenoid actuated mechanism. 
     
     
         5 . The fuel pump drive mechanism of  claim 3 , wherein the actuation mechanism includes a mechanically actuated mechanism. 
     
     
         6 . The fuel pump drive mechanism of  claim 1 , wherein the rocker arm includes a first side engaged with the cam lobe and the pump lifter and a second side opposite the first side engaged with the fulcrum member. 
     
     
         7 . The fuel pump drive mechanism of  claim 1 , wherein the first pump stroke corresponds to a first pump output capacity and the second pump stroke corresponds to a second pump output capacity less than the first pump output capacity. 
     
     
         8 . An engine assembly comprising:
 a fuel pump rocker arm having first and second ends;   a fulcrum member engaged with the rocker arm and displaceable between first and second positions, the fulcrum member engaging the rocker arm at a first location between the first and second ends when in the first position and engaging the rocker arm at a second location between the first location and the second end when in the second position;   a cam lobe engaged with the rocker arm at the first end to displace the rocker arm; and   a fuel pump including a lifter engaged with the rocker arm at the second end and being driven by the displacement of the rocker arm, the rocker arm providing a first pump stroke for the lifter when the fulcrum member is in the first position and a second pump stroke for the lifter less than the first pump stroke when the fulcrum member is in the second position.   
     
     
         9 . The engine assembly of  claim 8 , wherein the fulcrum member includes first and second pivot regions, the fulcrum member being rotatable from the first position where the first pivot region abuts the rocker arm at the first location to the second position where the second pivot region abuts the rocker arm at the second location. 
     
     
         10 . The engine assembly of  claim 8 , further comprising an actuation mechanism engaged with the fulcrum member and displacing the fulcrum member between the first and second positions. 
     
     
         11 . The engine assembly of  claim 10 , wherein the actuation mechanism includes an electrical solenoid actuated mechanism. 
     
     
         12 . The engine assembly of  claim 10 , wherein the actuation mechanism includes a mechanically actuated mechanism. 
     
     
         13 . The engine assembly of  claim 8 , wherein the rocker arm includes a first side engaged with the cam lobe and the pump lifter and a second side opposite the first side engaged with the fulcrum member. 
     
     
         14 . The engine assembly of  claim 8 , wherein the first pump stroke corresponds to a first pump output capacity and the second pump stroke corresponds to a second pump output capacity less than the first pump output capacity. 
     
     
         15 . The engine assembly of  claim 8 , wherein the fulcrum member engages the rocker arm at the first location during engine operation at a first engine speed and the fulcrum member engages the rocker arm at the second location during engine operation at a second engine speed greater than the first engine speed. 
     
     
         16 . A method comprising:
 operating an engine fuel pump at a first pump output capacity including engaging a fuel pump rocker arm at a first end with a cam lobe and engaging a fuel pump lifter with a second end of the rocker arm, the rocker arm being supported at a first location between the first and second ends by a fulcrum member and the rocker arm providing a first pump stroke corresponding to the first pump output capacity; and   operating the engine fuel pump at a second pump output capacity less than the first pump output capacity including supporting the rocker arm at a second location between the first location and the second end and engaging the rocker arm at the first end with the cam lobe and engaging the fuel pump lifter with the second end of the rocker arm to provide a second pump stroke less than the first pump stroke.   
     
     
         17 . The method of  claim 16 , further comprising switching between the first and second pump output capacities by rotating the fulcrum member from a first position where a first pivot region of the fulcrum member abuts the fuel pump rocker arm at the first location to a second position where a second pivot region of the fulcrum member abuts the fuel pump rocker arm at the second location. 
     
     
         18 . The method of  claim 16 , wherein the fuel pump is operated at the first pump output capacity during engine start-up. 
     
     
         19 . The method of  claim 16 , wherein the fuel pump is operated at the first pump output capacity at engine speeds below 1000 revolutions per minute. 
     
     
         20 . The method of  claim 16 , wherein the fuel pump is operated at the second pump output capacity at engine speeds above 1000 revolutions per minute.