A plurality of teeth are provided to protrude in staggered arrangement in an annular core in a circumferential direction, coils are respectively wound around the respective teeth, and when the respective coils are energized, corresponding teeth are excited to thereby form a plurality of magnetic circuits having an inclination of +45 degrees or −45 degrees with respect to an axial center direction of an object to be detected between the teeth and the facing object to be detected.

This invention concerns torque sensor systems and methods that computationally compensate in real-time for hysteresis in signals output from sense elements that are indicative of a torque, including a time-varying torque. In preferred embodiments, temperature effects can also be compensated for by such methods and systems.

A torque sensor to detect torque transmitted by a shaft having magnetostrictive properties is provided with a pair of cylindrical detection units arranged around the shaft and aligned side-by-side in an axial direction of the shaft, and first and second connection lines connecting the pair of detection units. Each detection unit includes first to fourth detection coils stacked in a radial direction. A series circuit formed by series connecting the first and fourth detection coils is parallel connected to a series circuit formed by series connecting the second and third detection coils. The first and second connection lines are configured to connect between corresponding connecting portions of the first and fourth detection coils and between corresponding connecting portions of the second and third detections coils, respectively. The torque transmitted by the shaft is detected based on a potential difference between the first connection line and the second connection line.

A magnetostrictive torque sensor includes detection coils formed around a magnetostrictive material made of chrome steel or chrome molybdenum steel, a magnetic ring configured to cover around the detection coils, and a drive unit for providing alternating current excitation to the detection coils at an excitation frequency of 50 kHz or more and 333 kHz or less. A torque applied to the magnetostrictive material is detected based on a change in inductance of the detection coils. The magnetic ring is configured by wrapping around the detection coils with an amorphous tape made of amorphous soft magnetic material in a tape shape. The thickness of the magnetic ring is 1.455 times or more as thick as a skin effect thickness of the magnetostrictive material and less than 1.000 mm.

The torque measuring device includes: a casing made of a magnetic metal; a rotating shaft rotatably arranged inside the casing and having a magnetostrictive effect section whose magnetic permeability changes according to torque to be transmitted; and a torque sensor arranged around the magnetostrictive effect section and supported by the casing, the torque sensor including a coil unit formed in a cylindrical shape using a flexible substrate having a detection coil that changes voltage in response to changes in the magnetic permeability of the magnetostrictive effect section, and a holder made of rubber or synthetic resin, covering an outer peripheral surface of the coil unit, and having a portion that protrudes from the coil unit on both sides in an axial direction; and the torque sensor supported by the casing with an outer peripheral surface of the holder fitted into an inner peripheral surface of the casing.

A torque measuring device includes a bridge circuit in which four detection coils arranged around a magnetostrictive effect section of a rotating shaft are arranged on four sides; and the bridge circuit includes a resistance element connected to at least one of the four sides for adjusting a resistance value of the side.

A torque measuring device includes: a coil unit having a detection coil configured to change a voltage in response to a change in magnetic permeability of a magnetostrictive effect section of a rotating shaft; a back yoke arranged coaxially around the coil unit; a holder configured to hold the coil unit and the back yoke; and an electronic circuit including the detection coil and configured to generate an output voltage according to a voltage of the detection coil, a clearance in a radial direction is provided between an outer peripheral surface of the coil unit and an inner peripheral surface of the back yoke, and a range of change in the clearance that accompanies temperature change during use is regulated to a range in which a change in the output voltage is linear with respect to the change in the clearance.

The manufacturing method includes: performing testing of samples having the same configuration as the torque measuring device to be manufactured to find a coil balance C.sub.b that is a ratio (R1×R3)/(R2×R4) of a product R1×R3 of resistance values R1 and R3 of one pair of opposite sides of the four sides of a bridge circuit 8, and a product R2×R4 of resistance values R2 and R4 of another pair of opposite sides of the four sides, and a temperature change rate V.sub.T of output voltage Vo of a sensor portion 4, and acquiring a relationship X between the coil balance C.sub.b and the temperature change rate V.sub.T from the test results; and measuring the resistance values R1, R2, R3, R4 of the four sides to find the coil balance C.sub.b to find the temperature change rate V.sub.T from the relationship X for the torque measuring device to be manufactured.

A torque transmitter for a torque sensor for measuring a torque on a shaft includes a carrier plate that includes a plurality of sensor element carrier plate regions, on each of which at least one sensor element for recording magnetic field changes is arranged, and an enclosure region formed in a substantially annular shape to enclose the shaft around a circumference of the shaft. The plurality of sensor element carrier plate regions are perpendicularly connected to the enclosure region and arranged radially within the enclosure region by being spaced apart along a circumferential direction around the circumference of the shaft.

A gap compensated stress sensing system and methods for using the same are provided. The system can include a sensor head in communication with a controller. The sensor head can contain a stress sensor configured to generate a stress signal representing stress applied to a target based upon measurement of generated magnetic fluxes passing through the target. The system can also include a drive circuit configured to provide a current for generation of the magnetic fluxes, and to measure signals characterizing a gap between the sensor head and the target. The controller can analyze these signals to determine a gap-dependent reference signal that is relatively insensitive to electrical runout. The controller can further adjust the stress signal based upon the gap-dependent reference signal to determine an improved stress signal that has reduced sensitivity to gap changes.