Magnetoelastic torque sensor with extended compensation for interference fields

A magnetoelastic torque sensor, comprising:

• a shaft having at least one magnetized region, the shaft having an axial direction and a radial direction;
• at least three magnetic field sensors, each having at least one measurement axis and being configured to acquire a component of a magnetic flux density of a magnetic field in a direction of the at least one measurement axis;
• and
• an evaluation unit;
• wherein the at least three magnetic field sensors include a first magnetic field sensor, a second magnetic field sensor, and a third magnetic field sensor, the second magnetic field sensor being situated in the axial direction between the first magnetic field sensor and the third magnetic field sensor;
• wherein at least one of the at least three magnetic field sensors is situated relative to the at least one magnetized region in such a way that the at least one magnetic field sensor is set up to acquire a component of a magnetic flux density of a magnetic field, in the direction of the respective at least one measurement axis, the magnetic field being producible when there is a loading of the shaft with a torque by the at least one magnetized region;
• and
• wherein the evaluation unit is configured to acquire at least one measurement signal of the first magnetic field sensor, at least one measurement signal of the second magnetic field sensor, and at least one measurement signal of the third magnetic field sensor, and to determine a torque exerted on the shaft based on the at least one measurement signal of the first magnetic field sensor, the at least one measurement signal of the second magnetic field sensor, the at least one measurement signal of the third magnetic field sensor, and a ratio of a distance between the second magnetic field sensor and the third magnetic field sensor in the axial direction to a distance between the first magnetic field sensor and the second magnetic field sensor in the axial direction.

A vehicle, comprising:

• a magnetoelastic torque sensor, including:
• a shaft having at least one magnetized region, the shaft having an axial direction and a radial direction,
• at least three magnetic field sensors, each having at least one measurement axis and being configured to acquire a component of a magnetic flux density of a magnetic field in a direction of the at least one measurement axis, and
• an evaluation unit,
• wherein the at least three magnetic field sensors include a first magnetic field sensor, a second magnetic field sensor, and a third magnetic field sensor, the second magnetic field sensor being situated in the axial direction between the first magnetic field sensor and the third magnetic field sensor,
• wherein at least one of the at least three magnetic field sensors is situated relative to the at least one magnetized region in such a way that the at least one magnetic field sensor is set up to acquire a component of a magnetic flux density of a magnetic field, in the direction of the respective at least one measurement axis, the magnetic field being producible when there is a loading of the shaft with a torque by the at least one magnetized region, and
• wherein the evaluation unit is configured to acquire at least one measurement signal of the first magnetic field sensor, at least one measurement signal of the second magnetic field sensor, and at least one measurement signal of the third magnetic field sensor, and to determine a torque exerted on the shaft based on the at least one measurement signal of the first magnetic field sensor, the at least one measurement signal of the second magnetic field sensor, the at least one measurement signal of the third magnetic field sensor, and a ratio of a distance between the second magnetic field sensor and the third magnetic field sensor in the axial direction to a distance between the first magnetic field sensor and the second magnetic field sensor in the axial direction;
• wherein the vehicle being operable electrically and/or with muscular force and having a crank drive, the magnetoelastic torque sensor being situated on the crank drive.

A method for determining a torque using a magnetoelastic torque sensor, the magnetoelastic torque sensor including:

• a shaft having at least one magnetized region, the shaft having an axial direction and a radial direction,
• at least three magnetic field sensors, each having at least one measurement axis and being configured to acquire a component of a magnetic flux density of a magnetic field in a direction of the at least one measurement axis, and
• an evaluation unit,
• wherein the at least three magnetic field sensors include a first magnetic field sensor, a second magnetic field sensor, and a third magnetic field sensor, the second magnetic field sensor being situated in the axial direction between the first magnetic field sensor and the third magnetic field sensor,
• wherein at least one of the at least three magnetic field sensors is situated relative to the at least one magnetized region in such a way that the at least one magnetic field sensor is set up to acquire a component of a magnetic flux density of a magnetic field, in the direction of the respective at least one measurement axis, the magnetic field being producible when there is a loading of the shaft with a torque by the at least one magnetized region, and
• wherein the evaluation unit is configured to acquire at least one measurement signal of the first magnetic field sensor, at least one measurement signal of the second magnetic field sensor, and at least one measurement signal of the third magnetic field sensor, and to determine a torque exerted on the shaft based on the at least one measurement signal of the first magnetic field sensor, the at least one measurement signal of the second magnetic field sensor, the at least one measurement signal of the third magnetic field sensor, and a ratio of a distance between the second magnetic field sensor and the third magnetic field sensor in the axial direction to a distance between the first magnetic field sensor and the second magnetic field sensor in the axial direction,
• the method comprising the following steps:
• acquiring a first measurement signal of the first magnetic field sensor;
• acquiring a second measurement signal of the second magnetic field sensor;
• acquiring a third measurement signal of the third magnetic field sensor;
• and
• determining a torque exerted on the shaft based on the first measurement signal, the second measurement signal, the third measurement signal, and the ratio of the distance between the second magnetic field sensor and the third magnetic field sensor in the axial direction to a distance between the first magnetic field sensor and the second magnetic field sensor in the axial direction.