The present invention relates to a method and an arrangement for determining the armature (1) position of an electromagnet. In the method the potential differences in the yoke (2) or in the armature (1), generated by a non-homogeneous eddy current distribution in the event of a deflection of the armature (1), are detected to determine the instantaneous armature (1) position relative to a reference position from these potential differences. For this purpose at least one voltage difference is measured between two measuring points on the yoke (2) or armature (1), or between one measuring point on the yoke (2) or armature (1) and a reference potential. The armature (1) position relative to a reference position on the electromagnet is then determined from this voltage difference. The method can be performed cost effectively, and can also easily be applied to existing electromagnets.

There is a solenoid including a stator having a first stator tooth and a second stator tooth, and an armature having a first armature tooth and a second armature tooth. The armature is moveable with respect to the stator over a predetermined stroke. A coil is associated with one of the stator and the armature for conducting an electric current and generating magnetic flux that is guided by the stator and the armature. The stator or the armature acts as a ferromagnetic core for the coil. There is a first air-gap between the first stator tooth and the first armature tooth that has a first length, and a second air-gap between the second stator tooth and the second armature tooth that has a second length. The first and second lengths are constant to within a predetermined margin over the predetermined stroke when the first and second armature teeth overlap the first and second stator teeth respectively.

The invention relates to a device for controlling armature solenoid provided with a DC voltage source (14), at least one buffer capacitor (18), which is connected in parallel to the DC voltage source (14) and has a known capacitance (C), and a first switch (28), which is arranged between the DC voltage source (14) and the buffer capacitor (18). The exciter coil (16) and a second switch (30) arranged in series therewith are connected in parallel to the buffer capacitor (18). A control and evaluation unit (22), when the buffer capacitor (18) is charged, opens the first switch (28) and closes the second switch (30) in order to determine, on the basis of the measurement voltage (20), the frequency of the resonant circuit having the capacitance (C) of the buffer capacitor (18) and the inductance (L) of the armature solenoid (12). The inductance (L) of the armature solenoid (12) is determined on the basis of the frequency, and the air gap width (h) of the armature solenoid (12) is determined on the basis of the inductance. The PWM control signal with which the armature solenoid (12) is operable in order to generate a predefined force to be applied by the armature solenoid (12) is applied to the second switch (30) on the basis of a look-up table or a mathematical modelling of the electromagnetic behavior of the armature solenoid (12).

An electrical assembly comprises a device. The device includes an inductive coil and an armature. The armature is arranged to be moveable between first and second positions when the inductive coil is energized. The electrical assembly further includes a detection unit which is configured to detect an inductance of the inductive coil or a characteristic that corresponds to the inductance of the inductive coil. The detection unit is further configured to determine the position of the armature based on the detected inductance or the detected characteristic.

A method may include generating an electrical drive waveform associated with a target actuator by stretching or compressing a reference drive waveform associated with a reference actuator in a time domain of the reference drive waveform in accordance with a time adjustment factor, wherein the time adjustment factor is determine based on a difference between a resonant frequency of the target actuator and a resonant frequency of the reference actuator. The same or another method may include generating an electrical drive waveform associated with a target actuator by increasing or decreasing an amplitude of a reference drive waveform associated with a reference actuator in accordance with an amplitude adjustment factor, wherein the amplitude adjustment factor is determined based on a difference between a resonant frequency of the target actuator and a resonant frequency of the reference actuator.

A method for determining a position of a movable element of a linear actuator of a motor vehicle includes supplying a current to a coil of the linear actuator so as to move and/or hold the movable element by a magnetic field of the coil generated by the supplied current; modulating the current supplied to the coil with an electrical alternating variable having a predetermined frequency; determining an impedance or an admittance of the coil at the predetermined frequency by measuring a further variable at the predetermined frequency; and determining the position of the movable element as a function of the determined impedance or admittance.

Methods and systems are provided for operating a solenoid actuator to engage and/or disengage a torque transmission member of a vehicle transmission. In one example, a method may include increasing the holding force of the solenoid actuator. Additionally, the solenoid actuator may include a translatable structural element that creates a moment upon touching another structural element holding the translatable element in a locked position.

Some embodiments provide irrigation valve control apparatuses comprising: a solenoid configured to cooperate with a plunger; an input stimulus source coupled with the solenoid and configured to apply an input stimulus while a plunger drive signal is not being applied and that is sufficiently small to not cause the plunger to move; sampling circuitry configured to measure one or more voltage measurements corresponding to one or more voltages across the solenoid, wherein the one or more voltage measurements are dependent upon the current position of the plunger relative to the solenoid; and control circuitry cooperated with the sampling circuitry to receive the one or more voltage measurements from the sampling circuitry, wherein the control circuitry is configured to determine whether the plunger is in one of the open and closed positions based on the one or more voltage measurements.

An apparatus and method of detecting movement of a plunger of the solenoid includes detecting a peak (I.sub.PEAK) in a current signal applied to a coil of the solenoid. A predetermined threshold is added to the current signal applied to the coil of the solenoid to generate a level shifted signal. The level shifted signal and the peak signal are compared to detect movement of a plunger of the solenoid.

An apparatus and method of detecting movement of a plunger of the solenoid includes detecting a peak (I.sub.PEAK) in a current signal applied to a coil of the solenoid. A predetermined threshold is added to the current signal applied to the coil of the solenoid to generate a level shifted signal. The level shifted signal and the peak signal are compared to detect movement of a plunger of the solenoid.