Sensor arrangement for an automated transmission and method for detecting a magnetic interference field

A method for ascertaining an external magnetic interference field by a sensor arrangement (46) for an automated transmission having a shifting device (2) including multiple shift rails (4, 14, 24, 34) arranged axially parallel to one another and being axially displaceable by associated shift actuators (8, 18, 28, 38), wherein the sensor arrangement (46) has multiple displacement sensors (48, 56, 64, 72), each of which comprises a signal transmitter (50, 58, 66, 74) attached to one of the shift rails (4, 14, 24, 34) and a signal receiver (52, 60, 68, 76) fixedly arranged on a housing, wherein the signal transmitters (50, 58, 66, 74) are each in the form of a permanent magnet having magnetic poles, wherein the signal receivers (52, 60, 68, 76) are each in the form of a 3D Hall sensor, and wherein the signal receivers (52, 60, 68, 76) are connected to an electronic transmission control unit (44) via electrical sensor lines (54, 62, 70, 78),

• wherein the signal transmitters (50, 58, 66, 74) are arranged having an identical axial alignment of their magnetic poles (N, S), and wherein the signal receivers (52, 60, 68, 76) are arranged in a common plane (80) that is horizontal in an installation position of the signal receivers,
• the method comprising the steps of:
• detecting sensor signals of each of the signal receivers (52, 60, 68, 76) at a fixed interval (ΔtS);
• storing current signal values (xS) of the sensor signals, and
• determining a presence of an external magnetic interference field in response to detecting that the signal values (xS) of at least two signal receivers (52, 60, 68, 76) simultaneously have a signal value change at a time when a gear change operation of the transmission has not been triggered.

A sensor arrangement (46) for an automated transmission, comprising:

• a shifting device (2) including multiple shift rails (4, 14, 24, 34), which are arranged so as to be axially parallel to one another and which are axially displaceable by associated shift actuators (8, 18, 28, 38),
• wherein the sensor arrangement (46) includes multiple displacement sensors (48, 56, 64, 72),
• wherein each of the displacement sensors comprises a signal transmitter (50, 58, 66, 74) attached to one of the shift rails (4, 14, 24, 34) and a signal receiver (52, 60, 68, 76) fixedly arranged on a housing,
• wherein the signal transmitters (50, 58, 66, 74) are each in the form of a permanent magnet having magnetic poles,
• wherein the signal receivers (52, 60, 68, 76) are each in the form of a 3D Hall sensor, and
• wherein the signal receivers (52, 60, 68, 76) are each connected to an electronic transmission control unit (44) via electrical sensor lines (54, 62, 70, 78),
• wherein the signal transmitters (50, 58, 66, 74) are arranged having an identical axial alignment of their magnetic poles (N, S), and
• wherein the signal receivers (52, 60, 68, 76) are arranged in a common plane (80) that is horizontal in an installation position of the signal receivers;
• wherein the ECU forms a mean value of the sensor signals and defines an inner tolerance range about the mean value and an outer interference range about the mean value that is greater than the inner tolerance range, and wherein the ECU establishes an observation period including a most recently detected sensor signal.