Variable discharge pump

Abstract

A variable discharge pump is provided, the pump comprising a pumping chamber and a reciprocating plunger disposed within a plunger bore so as to reciprocate within the pumping chamber. The pump also has an electrically actuated spill control valve which opens or closes fluid communication between the pumping chamber and a low pressure area. The control valve is operated for a first period of time extending from a first time point occurring after the plunger passes bottom dead center to a second time point occurring before the plunger passes top dead center. The control valve is then operated for a second period of time extending from a third time point occurring between the second time point and the passing of the plunger through top dead center to a fourth time point occurring after the plunger has passed top dead center.

1 . A pump comprising: 
 a first pumping chamber;    a first reciprocating plunger disposed within a first plunger bore so as to reciprocate within the first pumping chamber;    a first electrically actuated spill control valve adapted to open or close fluid communication between the first pumping chamber and a low pressure area; and    a controller adapted to operate the first control valve for a first period of time extending from a first time point occurring after the first plunger passes bottom dead center to a second time point occurring before the first plunger passes top dead center; and    the controller being adapted to operate the first control valve for a second period of time extending from a third time point occurring between the second time point and the passing of the first plunger through top dead center to a fourth time point occurring after the first plunger has passed top dead center.    
   
   
       2 . The pump according to  claim 1 , wherein the first control valve is a solenoid valve.  
   
   
       3 . The pump according to  claim 1 , wherein the controller comprises an electronic control unit.  
   
   
       4 . The pump according to  claim 3 , wherein the electronic control unit includes a data storage device which stores one or more fluid pressure parameters, and wherein the control unit is adapted to vary the operating of the first control valve according to the stored parameters.  
   
   
       5 . The pump according to  claim 3 , wherein the electronic control unit includes a receiver adapted to receive data relating to fluid pressure parameters from an external device, and wherein the control unit is adapted to vary the operating of the first control valve according to the received signals.  
   
   
       6 . The pump according to  claim 1  and including: 
 a second pumping chamber; and    a second reciprocating plunger disposed within a second plunger bore so as to reciprocate within the second pumping chamber;    wherein the first control valve is adapted to open or close fluid communication between the second pumping chamber and the low pressure area;    wherein the controller is adapted to operate the first control valve for a first period of time extending from the first time point occurring after one of the plungers passes bottom dead center to the second time point occurring before the one of the plungers moves through top dead center; and    wherein the controller is adapted to operate the first control valve for a second period of time extending from the third time point occurring between the second time point and the movement of the one of the plungers through top dead center to the fourth time point occurring after the one of the plungers has moved through top dead center.    
   
   
       7 . The pump according to  claim 6 , wherein the one of the plungers is the second plunger.  
   
   
       8 . The pump according to  claim 6 , wherein the first and second plungers are adapted so as to reciprocate out of phase with one another.  
   
   
       9 . The pump according to  claim 6  and including: 
 a spill passage fluidly connecting the first and second pumping chambers; and    a shuttle valve located in the spill passage and adapted to be exposed to fluid pressure in the first and second pumping chambers;    the shuttle valve including a shuttle valve member moveable between a first position in which the first pumping chamber is fluidly connected to the control valve and a second position in which the second pumping chamber is fluidly connected to the control valve.    
   
   
       10 . The pump according to  claim 9 , wherein the shuttle valve is a ball valve and the shuttle valve member is a ball.  
   
   
       11 . The pump according to  claim 6 , wherein the first control valve is a solenoid valve.  
   
   
       12 . The pump according to  claim 6 , wherein the controller comprises an electronic control unit.  
   
   
       13 . The pump according to  claim 12 , wherein the electronic control unit includes a data storage device which stores one or more fluid pressure parameters, wherein the control unit may vary the operation of the control valve according to the stored parameters.  
   
   
       14 . The pump according to  claim 13 , wherein the electronic control unit includes a receiver adapted to receive data relating to fluid pressure parameters from an external device, wherein the control unit may vary the operation of the control valve according to the received signals.  
   
   
       15 . The pump according to  claim 1  and including: 
 a second pumping chamber;    a second reciprocating plunger disposed within a second plunger bore so as to reciprocate within the second pumping chamber; and    a second electrically actuated spill control valve adapted to open or close fluid communication between the second pumping chamber and the low pressure area;    wherein the controller is adapted to operate the second control valve for a first period of time extending from a first time point occurring after the second plunger passes bottom dead center a second time point occurring before the second plunger moves through top dead center; and    wherein the controller is adapted to operate the second control valve for a second period of time extending from a third time point occurring between the second time point and the movement of the second plunger through top dead center to a fourth time point occurring after the second plunger has moved through top dead center.    
   
   
       16 . The pump according to  claim 15 , wherein the first and second plungers are adapted so as to reciprocate out of phase with one another.  
   
   
       17 . The pump according to  claim 15 , wherein the first control valve is a solenoid valve.  
   
   
       18 . The pump according to  claim 15 , wherein the second control valve is a solenoid valve.  
   
   
       19 . The pump according to  claim 15 , wherein the controller comprises an electronic control unit.  
   
   
       20 . The pump according to  claim 19 , wherein the electronic control unit includes a data storage device which stores one or more fluid pressure parameters, wherein the control unit may vary the operation of the control valve according to the stored parameters.  
   
   
       21 . The pump according to  claim 19 , wherein the electronic control unit includes a receiver adapted to receive data relating to fluid pressure parameters from an external device, wherein the control unit may vary the operation of the control valve according to the received signals.  
   
   
       22 . The pump according to  claim 15 , wherein the first and second control valves are actuatable towards a closed position when operated.  
   
   
       23 . The pump according to  claim 15  including first and second springs adapted to bias the first and second control valves, respectively, in the open position.  
   
   
       24 . An internal combustion engine including a pump according to  claim 1 .  
   
   
       25 . A method of pressurizing fluid in a pump, the method comprising the steps of: 
 supplying low pressure fluid to a pumping chamber;    reciprocating a plunger within the pumping chamber so as to force fluid from the pumping chamber;    returning a portion of the fluid from the pumping chamber through an electrically actuated spill control valve;    operating the electrically actuated spill control valve to pressurize the fuel in the pumping chamber during a forward stroke of the plunger; and    discharging the pressurized fuel through a discharge port in communication with the pumping chamber;    wherein the operating step includes operating the control valve for two separate periods of time, a first period of time extending from a first time point occurring after the plunger passes bottom dead center to a second time point occurring before the plunger passes top dead center, and a second period of time extending from a third time point occurring between the second time point and the passing of the plunger through top dead center to a fourth time point occurring after the plunger has passed top dead center.    
   
   
       26 . The method according to  claim 25  and including the step of receiving data relating to fluid pressure parameters from an external device, and varying one or both of the first and second periods of time of the operating step according to the received data.  
   
   
       27 . The method according to  claim 26 , wherein a dwell time period between the fourth time point of the operating step and the first time point of a subsequent operating step is varied according to the received data.  
   
   
       28 . The method according to  claim 26  further comprising the step of storing data relating to one or more fluid pressure parameters, and varying one or both of the first and second periods of time of the operating step according to the stored data.  
   
   
       29 . The method according to  claim 28 , wherein the fourth time point is varied according to the stored data and the received data.