Hydraulic accumulator health monitor

Abstract

A system and method to diagnose the operational health of a hydraulic accumulator are provided. The system can include a hydraulic accumulator selectively coupled to a hydraulic actuator, such as a swing motor. The accumulator can be charged by movement of the actuator. A pressure sensor can be associated with the accumulator to determine an accumulator pressure. A controller can be connected to the pressure sensor. The controller can determine a charge curve based on a relationship between an actuator operational parameter associated with the actuator movement and the accumulator pressure. The controller can compare the charge curve to a previously defined charge curve or range to determine an error between the charge curve and the previously defined charge curve or range. The degree of the error can be associated with the operational health of the accumulator, and if too large, the operator may be notified of the status.

What is claimed is: 
     
         1 . A system to diagnose a health of a hydraulic accumulator, the system comprising:
 a hydraulic actuator;   a hydraulic accumulator fluidly coupled to the hydraulic actuator, wherein the hydraulic accumulator is configured to be charged from movement of the actuator;   a pressure sensor associated with the hydraulic accumulator to determine an accumulator pressure; and   a controller in communication with the pressure sensor, the controller configured to:
 determine a relationship between an actuator operational parameter associated with the movement of the actuator and the accumulator pressure; and 
 compare the relationship to a previously defined relationship to determine an error, if any, between the determined relationship and the previously defined relationship. 
   
     
     
         2 . The system of  claim 1 , wherein the controller configured to:
 determine a charge curve based on the relationship between the actuator operational parameter associated with a movement of the actuator and the accumulator pressure; and   compare the charge curve to a previously defined charge curve to determine an error between the charge curve and the previously defined charge curve.   
     
     
         3 . The system of  claim 1 , wherein the actuator is a swing motor. 
     
     
         4 . The system of  claim 3 , wherein the actuator operational parameter is a swing angular position. 
     
     
         5 . The system of  claim 3 , wherein the actuator operational parameter is a swing angular speed. 
     
     
         6 . The system of  claim 1 , wherein the controller is configured to notify an operator if the error is outside a predefined threshold range. 
     
     
         7 . The system of  claim 1 , wherein the actuator is a hydraulic cylinder. 
     
     
         8 . The system of  claim 7 , wherein the actuator operational parameter is a linear position of the hydraulic cylinder. 
     
     
         9 . The system of  claim 7 , wherein the actuator operational parameter is a speed of the hydraulic cylinder. 
     
     
         10 . The system of  claim 1 , wherein a valve is fluidly coupled between the actuator and the hydraulic accumulator for selective charging of the hydraulic accumulator. 
     
     
         11 . A method of diagnosing an operational health of a hydraulic accumulator, the method comprising:
 moving a hydraulic actuator to charge a hydraulic accumulator fluidly coupled to the actuator,   storing an accumulator pressure during the movement of the actuator;   determining a relationship between an actuator operational parameter associated with the movement of the actuator and the accumulator pressure; and   comparing the determined relationship to a previously defined relationship to determine an error, if any, between the determined relationship and the previously defined relationship.   
     
     
         12 . The method of  claim 11 , further comprising:
 determining a charge curve based on the relationship between the actuator operational parameter associated with a movement of the actuator and the accumulator pressure; and   comparing the charge curve to a previously defined charge curve to determine an error between the charge curve and the previously defined charge curve.   
     
     
         13 . The method of  claim 11 , wherein the moving an actuator to a position step includes rotating a swing motor between a first position and a second position. 
     
     
         14 . The method of  claim 13 , wherein the actuator operational parameter includes a swing angular position. 
     
     
         15 . The method of  claim 11 , further including reducing the hydraulic accumulator to a minimum accumulator pressure prior to the moving step. 
     
     
         16 . The method of  claim 11 , further including notifying an operator if the error is outside a predefined threshold range about the relationship. 
     
     
         17 . The method of  claim 11 , wherein the moving an actuator to a position step includes moving a hydraulic cylinder between a first position and a second position. 
     
     
         18 . The method of  claim 17 , wherein the actuator operational parameter includes a linear position. 
     
     
         19 . A machine comprising:
 a pump;   a hydraulic actuator selectively moved by fluid provided by the pump;   a hydraulic accumulator fluidly coupled to the hydraulic actuator, wherein the hydraulic accumulator is configured to be charged with pressurized fluid resulting from movement of the actuator;   a pressure sensor associated with the hydraulic accumulator to determine an accumulator pressure; and   a controller in communication with the pressure sensor, the controller configured to:
 determine a relationship between an actuator operational parameter associated with the movement of the actuator and the accumulator pressure; and 
 compare the relationship to a previously defined relationship to determine an error, if any, between the determined relationship and the previously defined relationship. 
   
     
     
         20 . The machine of  claim 19 , wherein the hydraulic actuator is a hydraulic swing motor, and the actuator operational parameter is a swing angular position.