A rotational angle detection device includes a first gear that rotates about a first rotation axis and that has a main surface having an annular shape that crosses the first rotation axis and a plurality of first teeth provided on the main surface; a second gear that rotates about a second rotation axis in engagement with the first gear and that has a larger number of second teeth than the first teeth; and a sensor that detects a rotational angle of the second gear. The second rotation axis extends in a direction orthogonal to both of a virtual line that connects a center of the first gear and a position where the first gear and the second gear are engaged with each other, and the first rotation axis. Each of the first teeth extends so as to shift from an outer side toward an inner side in a radial direction of the main surface as it shifts along a circumferential direction of the main surface. Adjacent two of the first teeth are disposed so as to overlap each other in the radial direction.

A system includes an encoder magnet, a magnetic field sensor, and a shield structure. The encoder magnet is configured to rotate about an axis of rotation and is configured to produce a measurement magnetic field. The magnetic field sensor is axially displaced away from the encoder magnet and is configured to detect the measurement magnetic field. The shield structure at least partially surrounds both of the encoder magnet and the magnetic field sensor for shielding against stray magnetic fields. The shield structure attaches to a secondary structure. The shield structure and the encoder magnet may be coupled via the secondary structure so that they are commonly rotational. Alternatively, the sensor package and the shield structure are coupled via the secondary structure so that they are nonrotational relative to the encoder magnet.

A multi-turn measurement system includes a plurality of gears, a plurality of pinions engaging the plurality of gears, a plurality of magnets each disposed on one of the plurality of gears, and a plurality of magnetic field sensors. Rotation of the pinions about a center axis drives rotation of the plurality of gears. The magnets each have a magnetic field that changes based on an angular position of the one of the plurality of gears. The magnetic field sensors are each positioned to sense the magnetic field of one of the plurality of magnets.

Embodiments herein are directed to steering position rotary sensors including a housing defining an internal cavity, a center shaft extending through the housing, and a gear coupled to the center shaft, wherein the gear is positioned off-center relative to a central rotational axis extending through the center shaft. The steering position rotary sensor may further include a magnet coupled to the gear, a first Hall effect sensor positioned adjacent the gear and concentric with the magnet, and a second Hall effect sensor positioned adjacent the center shaft and concentric with the central rotational axis, wherein the first Hall effect sensor and the second Hall effect sensor are separated by a magnetic shield.

Provided is a sensor device that is machinable and mountable easily. A sensor device includes an external gear configured to rotate together with a pinion shaft, driven gears configured to rotate by meshing with the external gear, permanent magnets configured to rotate together with the driven gears, magnetic sensors configured to detect magnetic fields of the permanent magnets, a circuit board assembly having the magnetic sensors mounted on a printed circuit board, a tubular first housing member that houses the external gear, and a second housing member that supports the driven gears and houses the circuit board assembly. The second housing member has a flange portion that abuts against an open end face of a fitting hole of the first housing member, and parts of the driven gears that protrude from the flange portion mesh with the external gear inside the first housing member.

Provided is an angle detection apparatus making it possible to reduce the labor of manufacturing while also suppressing bulkiness.

The angle detection apparatus includes a first rotating body (120), a second rotating body (122), a first transmission mechanism (111) that causes the second rotating body (122) to rotate by reducing a speed of a rotation of the first rotating body (120), a first angle detector (Ds) that detects a rotational angle of the first rotating body (120), another second angle detector (Dm) that detects a rotational angle of the second rotating body (122), and a processor (40) that specifies a number of revolutions (Rs) of the first rotating body (120). The processor (40) specifies the number of revolutions (Rs) while dynamically varying a specification condition for specifying the number of revolutions (Rs) according to a numerical value decided according to the detected rotational angle of the first rotating body (120) and a reduction ratio (G1) of the first transmission mechanism (111), and the detected rotational angle of the second rotating body (122).

Embodiments herein are directed to steering position rotary sensors including a housing defining an internal cavity, a center shaft extending through the housing, and a gear coupled to the center shaft, wherein the gear is positioned off-center relative to a central rotational axis extending through the center shaft. The steering position rotary sensor may further include a magnet coupled to the gear, a first Hall effect sensor positioned adjacent the gear and concentric with the magnet, and a second Hall effect sensor positioned adjacent the center shaft and concentric with the central rotational axis, wherein the first Hall effect sensor and the second Hall effect sensor are separated by a magnetic shield.

The present invention provides an absolute encoder suitable for reduction in thickness. An absolute encoder, for determining a rotation amount of a main spindle that rotates a plurality of revolutions, includes a first drive gear configured to rotate in accordance with rotation of the main spindle; a first driven gear that engages with the first drive gear; a second drive gear configured to rotate in accordance with rotation of the first driven gear; a second driven gear that engages with the second drive gear; and an angular sensor configured to detect a rotation angle at which a second rotating body is rotated in accordance with rotation of the second driven gear.

A wheel portion allows a shaft body that serves as a detection object to be inserted therein in a direction of a rotational axis from a position in front of the wheel portion, and is rotated about the rotational axis when the shaft body is rotated. The wheel portion includes a tubular portion in which the shaft body is inserted and a projecting edge portion extending away from the rotational axis at a front end of the tubular portion. The housing portion includes a cover portion having a hollow tubular opening portion in which the shaft body is inserted. The cover portion and the wheel portion are engaged with each other such that the opening portion is located on an inner side of the projecting edge portion.

A rotary position sensor comprises a magnetic sensor for generating two independent signals indicative of at least two different order magnetic fields, and a magnetic assembly forming a first magnetic field component having a first order at the location of the magnetic sensor, in which the first magnetic field component is rotatable relative to the magnetic sensor by receiving a first angle. The magnetic assembly is also adapted for forming a second magnetic field component having a second order, different from the first order, at the location of the magnetic sensor, in which the second magnetic field component is rotatable relative to the magnetic sensor and the first magnetic assembly by receiving a second angle. The position sensor comprises a processor for combining the two independent signals to produce a unique system state representative of the first and second angle.