In an angle-based crankshaft position sensing system, an electrical circuit is provided for also sensing the direction of rotation of the crankshaft. A slotted target wheel is coupled to the crankshaft and a single dual-element MR sensor is juxtaposed with the target wheel. The elements generate respective detection signals when a slot passes by the elements, with the position of the slot being indicated as being directly under the sensor at the point in time when the detection signals intersect each other. Also, square waves are generated for each detection signal, and when the magnitude of the second square wave is non-zero when the falling edge of the first square wave occurs, a clockwise rotation is indicated. On the other hand, if the magnitude of the second square wave is zero when the falling edge of the first square wave occurs, a counterclockwise rotation is indicated.

The present invention features a method and an apparatus for sensing the speed and the direction of rotation of a motor. The apparatus of the invention has a timing wheel disk that is attached to the rotational shaft of a motor and has a number of slots. Opposite the timing wheel are mounted two spaced-together proximity sensors that are a given or a fixed distance apart. The sensors are spaced to read within each slot of the disk at any given point during in the rotation of the timing wheel. When the sensors detect the edges of each slot of the rotating wheel, signals are generated. The sensors respectively define sensing channels A and B. A microcontroller contains a logic program that calculates the motor's speed and direction. Speed is determined by measuring the time that it takes for a point (the edge of a rotating disk's slot) to travel across both sensors. Direction is determined by storing the logic level of the first sensor (channel A) while a generated exclusive OR signal is high, and then analyzing the level of channel A when the exclusive OR is low. Channel A changes logic states over the exclusive OR period when the motor is rotating clockwise; it remains at the same logic state over the exclusive OR period when the motor is rotating counterclockwise. The invention requires no coupling or interface between the sensors. No moving parts are required by this invention, since the timing wheel is mounted directly upon the motor shaft, and the sensors are fixedly mounted adjacent the timing wheel on the brake drum, which requires no special bracketing.

A method is described for determining a rotation speed and a rotation direction of a component (2), in particular a transmission output shaft, with a sensor device (1). In the sensor device (1), as a function of a rotation speed and direction of the component (2), a first sensor signal and a second sensor signal are generated, which are phase shifted relative to one another and each of which, on reaching an upper switching threshold or a lower switching threshold in the sensor device (1), triggers a switching signal. When there are alternating, consecutive switching signals of the two sensor signals, the sensor device (1) emits a pulse signal as a function of which a variation of a sensor signal is generated, which is used to determine a rotation speed of the component (2). After a rotation direction reversal of the component (2) a pulse signal of the sensor device (1) is only generated after sensing a rotation movement of the component (2), this rotation movement of the component (2) being sensed when, in alternation, a switching signal of one sensor signal is followed by a switching signal of the other sensor signal.

A proximity sensor which includes a bar magnet having opposing North and South poles and two magnetic responsive sensors disposed on a lateral face of the magnet between the opposing North and South poles and a pair of corresponding flux concentrators, configured such that the magnetic responsive sensors are sandwiched between the magnet and the flux concentrators along a lateral face of the magnet between opposing pole faces forming a dual-element sensor assembly. In one embodiment the dual-element sensor assembly is adapted to be utilized with a two-channel ferrous target, a target wheel having ferrous targets that are axially separated to correspond to the two-channel sensor assembly. In this embodiment the sensors are configured such that the longitudinal axis of the sensor is generally parallel to the axis of rotation of the ferrous target wheel. In order to provide the directional information, the targets on each channel are also angularly separated on the ferrous target wheel to provide a unique logic sequence for each direction of rotation. In an alternate embodiment the dual element sensor assembly is utilized with a single channel target wheel with the sensors aligned such that the longitudinal axis of the sensor assembly is generally perpendicular to the axis of rotation of the ferrous target such that the sensors are sequentially disposed to a single channel target as the target wheel rotates. Similar to the other embodiment, the alternative embodiment is also able to provide a unique logic sequence depending on the direction of rotation of the ferrous target wheel. Thus, the sensor in accordance with the present invention is not only able to sense the proximity of a ferrous target, but also the direction of rotation of the ferrous target wheel.

In a tachogenerator for detecting the rotation speed of a rotating machine part, in particular that of a vehicle wheel, having a predetermined measurement resolution, having at least one magnetically acting encoder which can rotate with the machine part, has magnetically acting areas which are subdivided in a predetermined sequence into angle parts, in particular teeth composed of ferromagnetic material or a magnetic pole ring, and which, during rotation, produces a measurement signal in at least one magnet sensor which is arranged to be stationary relative to the encoder and is separated from said encoder by an air gap, which measurement signal corresponds to the angular pitch of the encoder and whose frequency corresponds to the rotation frequency of the machine part, in order to produce measurement signals which can be evaluated with an air gap which is not constant, the angular pitch of the encoder is coarser than the predetermined measurement resolution requires, and at least two magnet sensors are provided, which are arranged fixed one behind the other in the rotation direction, relative to the encoder, in order to produce at least two mutually phase-shifted measurement signals which correspond to the angular pitch of the encoder, and means are provided for linking the measurement signals emitted by the sensors to form an output signal, with the output signal being at a frequency which is greater than the measurement signals of the magnet sensors, in order to achieve the predetermined measurement resolution.