Method for control of an electronic liquid dispenser and associated dispenser system

1. A control method for an electronic liquid dispenser, wherein the liquid dispenser utilizes a motor to drive a pump mechanism from a home position in a dispense cycle for dispensing a metered dose of liquid from a reservoir, the motor powered by a voltage source, the method comprising:

upon initiation of the dispense cycle, starting the motor to operate the pump mechanism;

calculating motor work being performed by the motor immediately after motor start;

upon the calculated motor work immediately after motor start exceeding a first set point work value during initiation of the dispense cycle, stopping and reversing the motor to return the pump mechanism to the home position;

during the subsequent dispense cycle, separately detecting motor voltage and motor current; and

upon the calculated motor work being greater than a second set point work value and less than the first set point work value, stopping and reversing the motor to return the pump mechanism to the home position when (a) detected voltage fails below a set point voltage value or (b) detected current exceeds a set point current value.

2. The control method as in claim 1 , wherein motor work is calculated as a function of motor current, motor voltage, and run time of the motor.

3. The control method as in claim 1 , wherein motor work is calculated as a function of motor voltage, motor resistance, and run time of the motor.

4. The control method as in claim 1 , wherein the motor work is calculated immediately after start of the motor and the first set point work value immediately after start of the motor is defined to detect an initial jam of the motor and reverse the motor.

5. The control method as in claim 1 , wherein the pump mechanism generates a normal, repeatable motor current or motor voltage profile during a normal dispense cycle, the method further comprising monitoring and detecting for deviations of motor current and motor voltage from the normal current or voltage profile and, when a deviation is detected in motor current or motor voltage, calculating motor work a second time and reversing the motor when the calculated motor work exceeds the set point work value.

6. The control method as in claim 5 , wherein the normal motor current profile includes an increase in motor current at the home position of the pump mechanism, the method further comprising detecting the increase in motor current at the end of the dispense cycle before stopping the motor.

7. The control method as in claim 5 , wherein the normal motor voltage profile includes a decrease in motor voltage at the home position of the pump mechanism, the method further comprising detecting the decrease in motor voltage at the end of the dispense cycle before stopping the motor.

8. The control method as in claim 5 , wherein the normal motor current profile includes an initial increase and subsequent decrease in motor current during the dispense cycle, the method further comprising detecting the decrease in motor current before the calculated motor work exceeds the set point value.

9. The control method as in claim 5 , wherein the normal motor voltage profile includes an initial decrease and subsequent increase in motor voltage during the dispense cycle, the method further comprising detecting the increase in motor voltage before the calculated motor work exceeds the set point value.

10. The control method as in claim 1 , wherein after the motor is reversed, motor current is monitored for an increase in motor current before stopping the motor, the increase in motor current being an indication that the pump mechanism has returned to the home position.

11. The control method as in claim 10 , wherein before the increase in motor current is detected, motor current is monitored for steady or decreasing current for a defined time period.

12. The control method as in claim 1 , wherein after the motor is reversed, motor voltage is monitored for a decrease in motor voltage before stopping the motor, the decrease in motor voltage being an indication that the pump mechanism has returned to the home position.