Constant Net Implement Pump Valve Flow

Abstract

A control system for a machine having a cylinder and an accessory is disclosed. The control system may include a pump configured to provide fluid to the cylinder and the accessory, and a controller operatively connected to the pump. The controller may be configured to operate the pump to provide a primary flow to the cylinder at up to a predetermined maximum level for the cylinder. The predetermined maximum level for the cylinder may be less than a maximum flow capability of the pump. The controller may also be configured to operate the pump to provide a secondary flow to the accessory utilizing a remaining fluid.

1 . A control system for a machine having a cylinder and an accessory, the control system comprising:
 a pump configured to provide fluid to the cylinder and the accessory; and   a controller operatively connected to the pump, the controller configured to:
 operate the pump to provide a primary flow to the cylinder at up to a predetermined maximum level for the cylinder,
 the predetermined maximum level for the cylinder being less than a maximum flow capability of the pump, 
 the maximum flow capability of the pump being equal to or greater than the predetermined maximum level for the cylinder plus a predetermined maximum level for the accessory, and 
 
 operate the pump to provide a secondary flow to the accessory utilizing a remaining portion of the fluid,
 the secondary flow being provided to the accessory at up to the predetermined maximum level for the accessory. 
 
   
     
     
         2 . (canceled) 
     
     
         3 . The control system of  claim 1 , wherein the control system further comprises an engine coupled to the pump,
 wherein the engine is configured to drive the pump, and   wherein the controller is in operative communication with the engine and is further configured to adjust a speed of the engine such that the pump provides the primary flow to the cylinder and the secondary flow to the accessory.   
     
     
         4 . The control system of  claim 1 , wherein the accessory is a cooling fan. 
     
     
         5 . The control system of  claim 1 , further comprising a second pump configured to provide additional flow to the cylinder. 
     
     
         6 . The control system of  claim 1 , wherein the controller is further configured to receive a signal indicative of an operator request for the cylinder. 
     
     
         7 . The control system of  claim 6 , wherein the controller is further configured to calculate a pump displacement based at least in part on the operator request for the cylinder. 
     
     
         8 . The control system of  claim 7 , wherein the controller is further configured to calculate the pump displacement based at least in part on a desired fan speed. 
     
     
         9 . The control system of  claim 8 , wherein the controller is further configured to calculate the pump displacement based at least in part on an engine speed. 
     
     
         10 . The control system of  claim 9 , wherein the controller is further configured to control the pump according to the calculated pump displacement in order to provide the primary flow to the cylinder and the secondary flow to the accessory. 
     
     
         11 . A machine, comprising:
 a linkage;   a cylinder operatively connected to the linkage;   an accessory;   a first pump configured to provide fluid flow to move the cylinder and the accessory;   an engine coupled to the first pump and configured to drive the first pump; and   a controller in operative communication with the first pump and the engine, the controller configured to:
 determine an amount of primary flow to the cylinder,
 the amount of primary flow to the cylinder being less than a maximum flow capability of the first pump, 
 the maximum flow capability of the first pump being equal to or greater than a sum of a predetermined maximum level for the cylinder and a predetermined maximum level for the accessory, 
 
 determine an amount of secondary flow to the accessory,
 the amount of secondary flow being less than or equal to the maximum flow capability of the first pump minus the determined amount of primary flow to the cylinder, 
 
 calculate a displacement of the first pump to provide the determined amount of primary flow to the cylinder at up to the predetermined maximum level for the cylinder and provide the determined amount of secondary flow to the accessory at up to the predetermined maximum level for the accessory, and 
 control the first pump according to the calculated displacement. 
   
     
     
         12 . (canceled) 
     
     
         13 . The machine of  claim 11 , wherein the controller is further configured to adjust a speed of the engine such that the first pump provides the determined amount of primary flow to the cylinder and the determined amount of secondary flow to the accessory. 
     
     
         14 . The machine of  claim 11 , wherein the machine is a hydraulic excavator. 
     
     
         15 . The machine of  claim 11 , wherein the controller is further configured to determine the amount of primary flow to the cylinder independent of the amount of secondary flow to the accessory. 
     
     
         16 . The machine of  claim 11 , wherein the accessory is a cooling fan. 
     
     
         17 . The machine of  claim 16 , wherein the controller is further configured to calculate the displacement of the first pump based on an operator request for the cylinder, a desired fan speed, and a speed of the engine. 
     
     
         18 . The machine of  claim 11 , further comprising a second pump configured to provide fluid flow to the cylinder,
 wherein the controller is in operative communication with the second pump, and   wherein the controller is further configured to:
 calculate a displacement of the second pump to provide an additional flow to the cylinder, and 
 control the second pump according to the calculated displacement. 
   
     
     
         19 . The machine of  claim 18 , wherein the calculated displacement of the first pump is greater than the calculated displacement of the second pump. 
     
     
         20 . A control system for a machine having a cylinder and an accessory, the control system comprising:
 an engine;   a pump coupled to the engine,
 the pump configured to convert mechanical energy from the engine into fluid flow for the cylinder and the accessory; and 
   a controller in operative communication with the engine and the pump, the controller configured to:
 determine an amount of primary flow to the cylinder based at least in part on an operator request for the cylinder, 
 determine an amount of secondary flow to the accessory based at least in part on a desired fan speed, 
 calculate a speed of the engine to provide the determined amount of primary flow to the cylinder and the determined amount of secondary flow to the accessory, and 
 operate the engine according to the calculated speed of the engine. 
   
     
     
         21 . The control system of  claim 20 , further comprising an additional pump configured to provide additional flow to the cylinder. 
     
     
         22 . The control system of  claim 20 , wherein the controller is configured to calculate the speed of the engine based on the determined amount of primary flow to the cylinder, the determined amount of secondary flow to the accessory, and a maximum flow capability of the pump.