A metering valve comprising a solenoid having: a coil mounted on a core; and an armature moveable axially with respect to the core and against a return bias in response to a current in the coil; a variable capacitor having a first plate mounted for movement with the armature and a second plate fixed with respect to the core. The metering valve comprises an electronic feedback loop which is used to adjust the current in the coil based on a feedback signal derived from of the capacitance of the variable capacitor. A reference capacitor may be provided having opposing third and fourth plates at a set separation. A valve body may house the solenoid, the variable capacitor and the reference capacitor.

A fluid dispensing device and method for controlling the device are provided. The device includes a housing defining a fluid outlet. A valve controls the flow of fluid to the outlet. A sensor is configured to detect an object outside of and proximate to the housing. A solenoid is configured to move the valve between an open position and a closed position. A controller is configured to receive the output signal of the sensor, determine a characteristic of noise in the output signal such as a level of noise; adjust at least one of a sampling rate of the output signal and an amount of filtering of the output signal responsive to the characteristic of noise in the output signal, and transmit a control signal to the solenoid responsive to the output signal.

Provided are embodiments for determining solenoid plunger position by performing a method which includes generating, by a first signal circuit, a first signal based at least in part on a pull-in current value of a current applied to a solenoid coil of a solenoid. The method further includes generating, by a second signal circuit, a second signal by applying a time delay to the first signal. The method further includes comparing, by a comparator circuit, the first signal and the second signal to determine whether a plunger of the solenoid has moved within the solenoid from a first position to a second position. The method further includes, responsive to determining that the plunger of the solenoid has moved within the solenoid from the first position to the second position, reducing the current applied to the solenoid coil of the solenoid from the pull-in current value to a hold current value.

A sprayer control system includes a plurality of smart nozzles each having at least one control valve with a valve operator, an electronic control unit for the valve operator, and one or more spray nozzles. The at least one control valve and the ECU control a flow rate of liquid agricultural product through the nozzles. A duty cycle modulator is in communication with the ECU and generates an applied duty cycle for the at least one control valve. The duty cycle modulator includes a specified duty cycle input having a specified duty cycle and a pressure monitor associated with the at least one control valve. A pressure comparator compares the valve pressure determined with the pressure monitor with a system pressure and generates a pressure error. An applied duty cycle generator generates the applied duty cycle based on the specified duty cycle modified by the pressure error.

A controller for a linear solenoid valve is configured to: calculate an average value of an exciting current within a period including a natural number multiple of the dither cycle as an average current value; execute a feedback control on a control value of the pulse width modulation signal such that a target value of the exciting current and the average current value match; and calculate a dither correction amount by multiplying a ratio between the control value of the pulse width modulation signal obtained by the feedback control and the average current value by a dither current value that is a current value corresponding to the dither correction amount and calculating the dither correction amount such that an increase in the exciting current due to the dither correction amount is canceled out by a decrease in the exciting current due to the dither correction amount within one dither cycle.

A fluid dispensing device and method for controlling the device are provided. The device includes a housing defining a fluid outlet. A valve controls the flow of fluid to the outlet. A sensor is configured to detect an object outside of and proximate to the housing. A solenoid is configured to move the valve between an open position and a closed position. A controller is configured to receive the output signal of the sensor, determine a characteristic of noise in the output signal such as a level of noise, adjust at least one of a sampling rate of the output signal and an amount of filtering of the output signal responsive to the characteristic of noise in the output signal, and transmit a control signal to the solenoid responsive to the output signal.

A method for actuating a valve with an electromagnetic valve drive through which electric current is conducted to open or close the valve or to hold the valve in an open or closed position includes receiving an opening signal, determining an adapted opening signal which is adapted to physical limits of the valve or valve drive, and determining a feed-forward signal for feed-forward control of an electric current to drive the electromagnetic valve drive to open the valve in reaction to the adapted opening signal. The method further includes calculating an actuation signal for actuating the valve drive using the feed-forward signal, and outputting the actuation signal.

This invention provides two methods for detecting mechanical or electrical faults in a solenoid valve. In the first method, a force sensor is placed in the valve in such a way as to detect changes in the impact force of the plunger against the solenoid valve body or coil housing (depending upon the direction of movement of the plunger upon application of the electric current/magnetic field). A second method is provided which makes use of an accelerometer placed in such a way as to detect changes in the response of the plunger to the application of the magnetic field.

An electric current detection apparatus, the electric current detection apparatus is configured to detect an electric current flowing in a solenoid configured to be electrified by a PWM control, the apparatus includes a switch, an electric current value detection portion configured to detect a first electric current value at a first timing corresponding to a timing when the switch transitions from a closed state to an open state, the electric current value detection portion being configured to detect a third electric current value at a third timing, and a second electric current value calculation portion configured to calculate a second electric current value on the basis of the first electric current value and the third electric current value, the second electric current value being an electric current value of the electric current at the second timing.

A method for controlling a current flowing through a consumer comprises the following steps, which are periodically traversed: determining a dither current based on a dither signal and a definite point in time, wherein the dither signal is determined by a frequency, an amplitude and a signal form and actuating a flow control valve to produce the sum of a target current and the determined dither current by the consumer. Furthermore, the method comprises determining an indication to the current flowing through the consumer; compensating the indication by the factor of the dither current; and providing the indication, wherein the determination of the dither current and the determination of the indication are synchronized with each other in a predetermined way.