Method and device for determining a speed by means of an inductive speed sensor

A speed measurement device for determining a speed using a measurement sensor in a vehicle, comprising:

• at least one coil;
• a ferromagnetic transmitter element to change the inductance of the at least one coil;
• and
• at least one inductive speed sensor, including:
• the at least one coil;
• the ferromagnetic transmitter element;
• and
• an evaluation circuit;
• wherein the evaluation circuit is configured to record a change in the inductance of the at least one coil, and to determine the speed based on the changed inductance of the at least one coil,
• wherein in each case, there is one inductive speed sensor used as a wheel speed sensor for at least two wheels of the vehicle, and
• wherein the evaluation circuit is configured to recognize a reversal of the direction of movement of the ferromagnetic transmitter element with respect to the at least one coil or a reversal of the direction of travel of the vehicle from forward travel to reverse travel or from reverse travel to forward travel based on at least one temporal phase offset between the temporal profiles of the inductances recorded by the wheel speed sensors of the at least two wheels,
• wherein the wheel speed sensor includes a passive inductive speed sensor and an encoder, which is the ferromagnetic transmitter element, that is configured in the shape of a ring and rotates together with a wheel of the vehicle coaxially with respect to the wheel axis, wherein the wheel speed sensor also includes a stationary coil and a soft-magnetic core, wherein the coil surrounds the soft-magnetic core, and a common center axis of the coil and of the soft-magnetic core is arranged parallel to the wheel axis and perpendicular to a plane that is also perpendicular to the wheel axis, and
• wherein the ferromagnetic transmitter element has alternately protruding teeth and tooth gaps, wherein the wheel speed sensor includes the evaluation circuit that is coupled to the coil, wherein a gap is formed between the ferromagnetic transmitter element and an end of the soft-magnetic core pointing toward the transmitter element, wherein a permanent magnet is arranged on that end of the soft-magnetic core pointing away from the ferromagnetic transmitter element, and wherein the magnetic field of the permanent magnet on one side penetrates the soft-magnetic core, the coil and also the ferromagnetic transmitter element at least in places.

A driver assistance system, comprising:

• at least one speed measurement device for determining a speed using a measurement sensor in a vehicle;
• wherein the speed measurement device includes:
• at least one coil;
• a ferromagnetic transmitter element to change the inductance of the at least one coil;
• and
• at least one inductive speed sensor, including:
• the at least one coil;
• the ferromagnetic transmitter element;
• and
• an evaluation circuit;
• wherein the evaluation circuit is configured to record a change in the inductance of the at least one coil, and to determine the speed based on the changed inductance of the at least one coil,
• wherein in each case, there is one inductive speed sensor used as a wheel speed sensor for at least two wheels of the vehicle, and
• wherein the evaluation circuit is configured to recognize a reversal of the direction of movement of the ferromagnetic transmitter element with respect to the at least one coil or a reversal of the direction of travel of the vehicle from forward travel to reverse travel or from reverse travel to forward travel based on at least one temporal phase offset between the temporal profiles of the inductances recorded by the wheel speed sensors of the at least two wheels,
• wherein the wheel speed sensor includes a passive inductive speed sensor and an encoder, which is the ferromagnetic transmitter element, that is configured in the shape of a ring and rotates together with a wheel of the vehicle coaxially with respect to the wheel axis, wherein the wheel speed sensor also includes a stationary coil and a soft-magnetic core, wherein the coil surrounds the soft-magnetic core, and a common center axis of the coil and of the soft-magnetic core is arranged parallel to the wheel axis and perpendicular to a plane that is also perpendicular to the wheel axis, and
• wherein the ferromagnetic transmitter element has alternately protruding teeth and tooth gaps, wherein the wheel speed sensor includes the evaluation circuit that is coupled to the coil, wherein a gap is formed between the ferromagnetic transmitter element and an end of the soft-magnetic core pointing toward the transmitter element, wherein a permanent magnet is arranged on that end of the soft-magnetic core pointing away from the ferromagnetic transmitter element, and wherein the magnetic field of the permanent magnet on one side penetrates the soft-magnetic core, the coil and also the ferromagnetic transmitter element at least in places.

A vehicle, comprising:

• a driver assistance system;
• wherein the driver assistance system includes at least one speed measurement device for determining a speed using a measurement sensor in a vehicle, and wherein the speed measurement device includes:
• at least one coil;
• a ferromagnetic transmitter element to change the inductance of the at least one coil;
• and
• at least one inductive speed sensor, including:
• the at least one coil;
• the ferromagnetic transmitter element;
• and
• an evaluation circuit;
• wherein the evaluation circuit is configured to record a change in the inductance of the at least one coil, and to determine the speed based on the changed inductance of the at least one coil,
• wherein in each case, there is one inductive speed sensor used as a wheel speed sensor for at least two wheels of the vehicle, and
• wherein the evaluation circuit is configured to recognize a reversal of the direction of movement of the ferromagnetic transmitter element with respect to the at least one coil or a reversal of the direction of travel of the vehicle from forward travel to reverse travel or from reverse travel to forward travel based on at least one temporal phase offset between the temporal profiles of the inductances recorded by the wheel speed sensors of the at least two wheels,
• wherein the wheel speed sensor includes a passive inductive speed sensor and an encoder, which is the ferromagnetic transmitter element, that is configured in the shape of a ring and rotates together with a wheel of the vehicle coaxially with respect to the wheel axis, wherein the wheel speed sensor also includes a stationary coil and a soft-magnetic core, wherein the coil surrounds the soft-magnetic core, and a common center axis of the coil and of the soft-magnetic core is arranged parallel to the wheel axis and perpendicular to a plane that is also perpendicular to the wheel axis, and
• wherein the ferromagnetic transmitter element has alternately protruding teeth and tooth gaps, wherein the wheel speed sensor includes the evaluation circuit that is coupled to the coil, wherein a gap is formed between the ferromagnetic transmitter element and an end of the soft-magnetic core pointing toward the transmitter element, wherein a permanent magnet is arranged on that end of the soft-magnetic core pointing away from the ferromagnetic transmitter element, and wherein the magnetic field of the permanent magnet on one side penetrates the soft-magnetic core, the coil and also the ferromagnetic transmitter element at least in places.