Method and apparatus for diagnosing leakage in a fluid power system

A method of diagnosing leakage in a fluid power system including a fluid supply line operatively connected to a plurality of valves which are connected to a plurality of actuators, the method comprising the steps of:

• processing flow signals generated by a flow sensor disposed in the supply line to obtain fluid consumption over time;
• processing signals used to change the state of the plurality of valves to determine a plurality of episodes, each of the plurality of episodes corresponding to a pressurization of a particular branch of a particular actuator;
• combining the flow signals with the signals used to change the state of the valves to calculate a change in air consumption value, ΔFC, for each valve change of state;
• comparing the ΔFC values for each episode to a predetermined reference value to determine a deviation value corresponding to a particular one of the plurality of episodes;
• identifying the one of the plurality of episodes with the greatest deviation;
• and
• generating a signal indicating that a leak is present in the system and indicating the corresponding branch responsible for the leak.

A method of diagnosing leakage in a fluid power system including a fluid supply line operatively connected to a plurality of valves which are each connected to a corresponding actuator by a first and second fluid supply branch, the first and second branches of each actuator being selectively pressurized and exhausted by the corresponding valves, the method comprising the steps of:

• defining a plurality of episodes wherein each episode corresponds to a time period when one of the first and second branches of one of the plurality of actuators is pressurized;
• sensing the flow of fluid through the supply line to determine fluid consumption;
• calculating a change in fluid consumption value ΔFC, for each episode to obtain a ΔFC value for each branch;
• comparing the ΔFC value to a predetermined reference value for each of the branches of each of the plurality of actuators during a system cycle to obtain a deviation value for each of the first and second branches;
• calculating the difference between the deviation value of the first and second branches to obtain an actuator deviation value;
• comparing the actuator deviation values for each actuator to determine which of the plurality of actuators has the highest deviation value;
• comparing the actuator deviation values for the first and second branches for the actuator with the highest actuator deviation value to identify which one of the first and second branches has the highest deviation value;
• and
• generating a signal indicating that the one of the first and second branches with the highest deviation value has a leak.

A method of diagnosing leakage in a fluid power system including a fluid supply line operatively connected to a plurality of valves which are each connected to a corresponding actuator by a first and second branch, the first and second fluid supply branches of each actuator being selectively pressurized and exhausted by the corresponding valves, the method comprising the steps of:

• monitoring the plurality of valves to determine which branch of each of the plurality of actuators is pressurized;
• defining a plurality of episodes wherein each episode corresponds to a time period when one branch of one of the plurality of actuators is pressurized;
• sensing the flow of fluid through the supply line to determine an amount of fluid consumed for each episode to form a flow consumption curve;
• calculating an actual slope value for each branch from the flow consumption curve;
• comparing the actual slope value to a predetermined reference slope value for each of the branches of each of the actuators during a system cycle and generating a deviation value for each of the branches;
• calculating the difference between the deviation value of the first and second branches to obtain an actuator deviation value for each actuator;
• comparing the actuator deviation values for each actuator to each other to determine the actuator with the highest actuator deviation value;
• comparing the deviation values of the first and second branches of the actuator with the highest deviation value to determine which one of the first and second branches has the highest deviation value;
• and
• generating a signal indicating that the one of the first and second branches with the highest deviation value has a leak.

A method of diagnosing leakage in a fluid power system including a fluid supply line operatively connected to a plurality of valves which are each connected to a corresponding actuator by a first and second branch, the first and second branches of each actuator being selectively pressurized and depressurized by the corresponding valves, the method comprising the steps of:

• (a) calculating an actual total fluid consumption value for a system cycle;
• (b) comparing the actual total fluid consumption value to a predetermined reference total fluid consumption value, when the actual total fluid consumption value deviates a predetermined amount from the reference value then proceed to step (c), if the actual total fluid consumption value is deviated less than the predetermined amount from the reference value then return to step (a);
• (c) defining a plurality of episodes wherein each episode corresponds to a time period when one branch of one of the plurality of actuators is pressurized;
• (d) sensing the flow of fluid through the supply line to obtain fluid consumption values;
• (e) calculating a fluid consumption value for each episode to obtain a fluid consumption value for each branch;
• (f) comparing the fluid consumption value to a predetermined reference value for each of the branches of each of the plurality of actuators during a system cycle to obtain a deviation value for the first and second branch;
• (g) calculating the difference between the deviation value of the first and second branches to obtain an actuator deviation value;
• (h) comparing the actuator deviation values for each actuator to determine which of the plurality of actuators has the highest deviation value;
• (i) comparing the deviation values for first and second branches for the actuator with the highest actuator deviation value to identify which branch has the highest fluid consumption value;
• and
• (j) generating a signal indicating that the identified branch with the highest fluid consumption value has a leak.

An apparatus for diagnosing leakage in a fluid power system including a fluid supply line operatively connected to a plurality of valves which are each connected to a corresponding actuator by a first and second branch, the first and second branches of each actuator being selectively pressurized and depressurized by the corresponding valves, the apparatus comprising:

• a flow sensor disposed in the fluid supply line for sensing fluid flow to the plurality of valves;
• a monitoring device operatively connected to the flow sensor, the monitoring device including a processor and memory;
• a valve controller operatively connected to each of the plurality of valves and operatively connected to the monitoring device, the valve controller generating signals to cause the plurality of valves to shift state;
• the monitoring device defining a plurality of episodes wherein each episode corresponds to a time period when one branch of one of the plurality of actuators is pressurized;
• the monitoring device calculating a change in fluid consumption values, ΔFC, from signals received from the flow sensor;
• the monitoring device calculates a ΔFC value for each episode to obtain a ΔFC value for each branch and compares the ΔFC value to a predetermined reference value for each of the branches of each of the plurality of actuators during a system cycle to obtain a deviation value for the first and second branch;
• for each actuator, the monitoring device calculates the difference between the deviation value of the first and second branches to obtain an actuator deviation value, and compares the actuator deviation values for each actuator to determine which of the plurality of actuators has the highest deviation value;
• for the actuator with the highest deviation value, the monitoring device compares the fluid consumption values for first and second branches to determine which branch has the highest fluid consumption value, and generates a signal indicating that the branch with the highest fluid consumption value has a leak.