Pump control system for variable displacement pump

Abstract

A pump control system has pump-displacement controls configured to selectively activate and deactivate a predetermined pump-displacement limit between physical displacement limits of a variable-displacement pump. The pump-displacement controls may be configured to adjust an operating displacement of the variable-displacement pump within a range bounded by the predetermined pump-displacement limit when the predetermined pump-displacement limit has been activated. Further, the pump-displacement controls may be configured to adjust the operating displacement of the variable-displacement pump without restriction from the predetermined pump-displacement limit when the predetermined pump-displacement limit has been deactivated.

1 . A pump control system for a variable-displacement pump powered by a power source, comprising: 
 pump-displacement controls configured to: 
 selectively activate and deactivate a predetermined pump-displacement limit between physical displacement limits of the variable-displacement pump;  
 adjust an operating displacement of the variable-displacement pump within a range bounded by the predetermined pump-displacement limit when the predetermined pump-displacement limit has been activated; and  
 adjust the operating displacement of the variable-displacement pump without restriction from the predetermined pump-displacement limit when the predetermined-pump displacement limit has been deactivated.  
   
   
   
       2 . The pump control system of  claim 1 , wherein the pump-displacement controls automatically activate the predetermined pump-displacement limit in response to a predetermined condition.  
   
   
       3 . The pump control system of  claim 2 , wherein the predetermined condition relates to operations of the power source.  
   
   
       4 . The pump control system of  claim 2 , wherein the predetermined condition includes the power source operating outside a predetermined speed range.  
   
   
       5 . The pump control system of  claim 2 , wherein the predetermined condition includes the power source operating at idle speed.  
   
   
       6 . A method of controlling a variable-displacement pump that is powered by a power source, the method including: 
 selectively activating and deactivating a predetermined pump-displacement limit between physical displacement limits of the variable-displacement pump;    adjusting an operating displacement of the variable-displacement pump within a range bounded by the predetermined pump-displacement limit when the predetermined pump-displacement limit has been activated; and    adjusting the operating displacement of the variable-displacement pump without restriction from the predetermined pump-displacement limit when the predetermined-pump displacement limit has been deactivated.    
   
   
       7 . The method of  claim 6 , wherein pump-displacement controls automatically activate the predetermined pump-displacement limit in response to a predetermined condition.  
   
   
       8 . The method of  claim 7 , wherein the predetermined condition relates to operations of the power source.  
   
   
       9 . The method of  claim 7 , wherein the predetermined condition includes the power source operating outside a predetermined speed range.  
   
   
       10 . The method of  claim 7 , wherein the predetermined condition includes the power source operating at idle speed.  
   
   
       11 . The method of  claim 6 , wherein selectively activating the predetermined pump-displacement limit includes activating a displacement stop to move from a first position to a second position that is in a travel path of a displacement-control actuator, wherein the displacement-control actuator is movable to adjust the operating displacement of the variable-displacement pump.  
   
   
       12 . The method of  claim 11 , wherein the displacement stop includes a limit-activating piston, and selectively activating the predetermined pump-displacement limit includes moving the displacement stop from the first position to the second position by supplying pressurized fluid to the limit-activating piston.  
   
   
       13 . The method of  claim 12 , wherein the displacement-control actuator is a displacement-actuator piston disposed within a cylinder, at least a portion of the limit-activating piston is also disposed within the cylinder, and selectively activating the predetermined pump-displacement limit includes moving the displacement stop from the first position to the second position by supplying pressurized fluid to the limit-activating piston and moving the limit-activating piston toward the displacement-actuator piston.  
   
   
       14 . The method of  claim 11 , wherein selectively activating the predetermined pump-displacement limit includes pump-displacement controls moving the displacement stop from the first position to the second position in response to a predetermined condition.  
   
   
       15 . A pump control system for a variable-displacement pump powered by a power source of a work machine, comprising: 
 a displacement-control actuator movable to adjust the operating displacement of the variable-displacement pump;    a displacement stop movable between a first position and a second position that is in a travel path of the displacement-control actuator; and    displacement-stop controls configured to: 
 activate a predetermined pump-displacement limit by moving the displacement stop from the first position to the second position in response to a predetermined condition of the work machine.  
   
   
   
       16 . The pump control system of  claim 15 , wherein the displacement stop includes a limit-activating piston and the displacement-stop controls move the displacement stop from the first position to the second position by supplying pressurized fluid to the limit-activating piston.  
   
   
       17 . The pump control system of  claim 16 , wherein the displacement-control actuator is a displacement-actuator piston disposed within a cylinder and at least a portion of the limit-activating piston is also disposed within the cylinder.  
   
   
       18 . The pump control system of  claim 17 , further including: 
 a stop that limits travel of the limit-activating piston toward the displacement-actuator piston.    
   
   
       19 . The pump control system of  claim 15 , wherein the predetermined condition of the work machine relates to operations of the power source.  
   
   
       20 . The pump control system of  claim 15 , wherein the predetermined condition of the work machine includes the power source operating outside a predetermined speed range.