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US 12,235,134 B2Granted
Sensor for a magnetic measuring device
AssigneeRobert Bosch GmbH
InventorsMartin Joerg, Mathias Kimmerle, Peter Bigl
Life of this patent
Estimating the term…
Abstract
A sensor for a magnetic measuring device for detecting a rotational or translational movement of a body includes a permanent magnet which is connected to the body for conjoint rotation and which moves with the body. The sensor is fastened to a body by a method, and the sensor can be used in a magnetic measuring device for contactlessly detecting a rotational movement of a body. Plastic-bonded permanent magnet material is injection-molded onto the body, acting as an extension thereof, and forms a free end of the body acting as a permanent magnet.
Claims12
A sensor for a magnetic measuring device for detecting a rotational or translational movement of a shaft, comprising:
- a permanent magnet connected in a rotationally fixed manner to the shaft so as to move together with the shaft, the permanent magnet including a plastic bonded permanent magnetic material injection molded onto the shaft as an extension of the shaft that forms a free end of the shaft;
- and
- a fixing geometry of the shaft including a protruding structure with a mushroom-shaped protrusion cross section and a surrounding protrusion undercut,
- wherein the protruding structure protrudes directly from the shaft,
- wherein the permanent magnet completely encloses the protruding structure, such that a radial and axial positive engagement is formed between the permanent magnet and the shaft,
- wherein the shaft is cylindrical and defines a first diameter and a rotational axis,
- wherein the permanent magnet defines a cylindrical portion having a second diameter that is equal to the first diameter at an intersection of the cylindrical portion with the shaft,
- wherein the first diameter of the cylindrical portion is constant in a direction extending away from the shaft along the rotational axis,
- wherein the permanent magnet defines a tapered portion extending from the cylindrical portion opposite the intersection of the cylindrical portion with the shaft along the rotational axis,
- wherein the tapered portion has a plurality of diameters that decrease in size in the direction extending away from the shaft along the rotational axis,
- wherein the permanent magnet defines a front surface that intersects the tapered portion, the front surface being circular and flat, and the front surface defining a distal end of the permanent magnet, and
- wherein a third diameter of the front surface is substantially equal to a smallest diameter of the plurality of diameters of the tapered portion.
9 more elements
A method for fixing a sensor to a shaft, comprising:
- inserting an end of the shaft into a cavity of an injection molding tool, wherein a fixing geometry of the shaft includes a protruding structure with a mushroom-shaped protrusion cross section and a surrounding protrusion undercut, and the protruding structure protrudes directly from the inserted end of the shaft;
- introducing plastic bonded permanent magnetic material into the cavity of the injection molding tool, such that the plastic bonded permanent magnetic material cures and forms a free end of the shaft as an extension of the shaft that completely encloses the protruding structure, such that a radial and axial positive engagement is formed between the introduced permanent magnetic material and the shaft;
- and
- magnetizing the introduced permanent magnetic material in order to form a permanent magnet,
- wherein the shaft is cylindrical and defines a first diameter and a rotational axis,
- wherein the permanent magnet defines a cylindrical portion having a second diameter that is equal to the first diameter at an intersection of the cylindrical portion with the shaft,
- wherein the first diameter of the cylindrical portion is constant in a direction extending away from the shaft along the rotational axis,
- wherein the permanent magnet defines a tapered portion extending from the cylindrical portion opposite the intersection of the cylindrical portion with the shaft along the rotational axis,
- wherein the tapered portion has a plurality of diameters that decrease in size in the direction extending away from the shaft along the rotational axis,
- wherein the permanent magnet defines a front surface that intersects the tapered portion, the front surface being circular and flat, and the front surface defining a distal end of the permanent magnet, and
- wherein a third diameter of the front surface is substantially equal to a smallest diameter of the plurality of diameters of the tapered portion.
8 more elements
A magnetic measuring device, comprising:
- a shaft formed with a protruding structure configured to protrude from an end face of the shaft, the protruding structure having a mushroom-shaped cross section, and the protruding structure integrally formed with the shaft;
- a permanent magnet connected in a rotationally fixed manner to the shaft so as to move together with the shaft, the permanent magnet including a plastic bonded permanent magnetic material injection molded onto the shaft as an extension of the shaft that forms a free end of the shaft;
- and
- a measurement transducer arranged in a stationary manner and operably connected to the permanent magnet,
- wherein, depending on movement of the shaft, the permanent magnet influences at least one magnetic variable of a magnetic field detected by the measurement transducer,
- wherein the permanent magnet is configured to contactlessly influence the measurement transducer to detect movement of the shaft,
- wherein the permanent magnet completely encloses the protruding structure, such that a radial and an axial positive engagement is formed between the permanent magnet and the shaft,
- wherein the shaft is cylindrical and defines a first diameter and a rotational axis,
- wherein the permanent magnet defines a cylindrical portion having a second diameter that is equal to the first diameter at an intersection of the cylindrical portion with the shaft,
- wherein the first diameter of the cylindrical portion is constant in a direction extending away from the shaft along the rotational axis,
- wherein the permanent magnet defines a tapered portion extending from the cylindrical portion opposite the intersection of the cylindrical portion with the shaft along the rotational axis,
- wherein the tapered portion has a plurality of diameters that decrease in size in the direction extending away from the shaft along the rotational axis,
- wherein the permanent magnet defines a front surface that intersects the tapered portion, the front surface being circular and flat, and the front surface defining a distal end of the permanent magnet, and
- wherein a third diameter of the front surface is substantially equal to a smallest diameter of the plurality of diameters of the tapered portion.
11 more elements
Dependencies are inferred from the claim text.