Method and apparatus for monitoring and determining the functional status of an electromagnetic valve
AssigneeFesto AG & Co.
InventorsOliver Ahrens, Otto Szenn, Wjatscheslaw Missal, Karl-Heinz Forster
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Abstract
The present invention provides a method and apparatus for determining the functional status of an electromagnetic valve having a solenoid and plunger including determining the electro-mechanical switching time of a valve based on characteristics of an electrical characteristic responsive to the solenoid; comparing the valve electro-mechanical switching time to a predetermined value; and generating a valve status signal dependant on the results of the comparison.
Claims24
A method of determining a functional status of an electro-mechanical valve having a solenoid and plunger comprising the steps of:
- determining an electro-mechanical switching time, (tems), of a valve based on an electrical characteristic responsive to the solenoid;
- determining the (tems) includes determining a beginning and an end of a time window, and wherein determining the beginning of the time window includes the steps of:
- evaluating the current supplied to the solenoid over time;
- evaluating a valve switching pilot voltage (Vc) over time;
- determining when a slope of the (Vc) reaches a predetermined negative value and assigning that time as a switch on time;
- and
- adding a predetermined time value to the switch on time to determine the beginning of the time window;
- comparing the (tems) to a tolerance value;
- and
- generating a valve status signal dependant on a result of the comparison.
A method of monitoring the functional status of an electro-mechanical valve having a solenoid coil and plunger comprising the steps of:
- energizing the solenoid coil to initiate movement of the solenoid plunger from a first position to a second position;
- acquiring a signal relating to an electrical characteristic responsive to the solenoid;
- performing an algorithm on the signal to determine when the plunger reaches the second position;
- determining a time value based on the plunger movement between the first and second position including the step of staffing a timer upon energizing the solenoid and stopping the timer when the plunger reaches the second position;
- comparing the time value to a lower and an upper tolerance value;
- and
- indicating a functional status of the valve based on the comparison.
A method of determining a functional status of an electromagnetic valve having a solenoid and plunger comprising the steps of:
- determining a time value for the plunger to move between an initial position and a final position based on a first electrical characteristic responsive to the solenoid;
- comparing the time value to a tolerance range including an upper and lower limit;
- sensing a second electrical characteristic responsive to the solenoid and determining the tolerance range responsive to the second electrical characteristic;
- and
- generating a valve status signal indicating a defective valve if the time value falls outside of the tolerance range.
Dependencies are inferred from the claim text.