Other

Philips Electronics North America Corporation

Siemens Vdo Automotive Corporation

Continental Automotive Systems Corporation

Jon W Bossoli

Brian David Kilmartin

Carl Gandarillas

Dariusz Pszczola

A method for producing a low-hysteresis magnetoelastic element comprising applying a magnetoelastic material onto a metal substrate. After the magnetoelastic element is securely bonded to the underlying shaft, a reduction in the outside diameter of the shaft draws the magnetoelastic element radially inward causing it to occupy a smaller volume. This process provides the magnetic anistropy required for the sensor to operate properly, and also results in a densification of the magnetoelastic element making it inherently stable. Several methods of reducing the outside diameter of the shaft to draw the magnetoelastic element radially inward have been devised. Prior to deposition of the magnetoelastic material, the outside diameter of a hollow shaft is elastically expanded by applying force to its inside diameter. This is accomplished by using an expanding insert, by pressurizing the cavity within the shaft, or by inducing a managed thermal expansion of the shaft prior to material deposition. Post-deposition operation can also be implemented to reduce the shaft diameter, such as drawing the shaft axially until it yields. Any process that results in a shaft reduction after the magnetoelastic active material is deposited on the shaft can be used in the present invention.

Imparting compressive hoop stress into a bonded magnetoelastic element by means of diameter reduction of the underlying shaft

A coupler acts as an interface between a torque element of a torque sensor and a shaft receiving an applied torque. A portion of the shaft is allowed to twist freely inside the element, and the coupler transfers a portion of the torsion forces in the shaft to the element. The element deforms and generates a magnetic field or other torque response corresponding to the applied torque in the shaft. The applied torque can then be determined based on a relationship between the torque in the shaft and the torque in the element. Reducing the torsion forces applied to the element allows the element to measure higher applied torques without permanently deforming.

Coupler for torque sensor

A magnetoelastic layer is provided on a shaft for sensing torque carried by the shaft around a longitudinal axis. The layer includes first and second adjacent annular parts of a magnetically anisotropic material with circumferential easy axes. The parts are magnetically polarized in opposite circumferential directions when in a quiescent state, but produce helical magnetic fields with respective axial components when torque is carried by the shaft. First and second magnetic-field-guiding structures combine to provide shielding of the magnetoelastic layer from ambient external magnetic fields and to maximize coupling of the axial components from the magnetoelastic layer to one or more magnetic field detectors.

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Cheshire, CT, United States of America

Jon W Bossoli