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Magnetoelastic

For the first time, the measurement of torque within an automotive transmission is not only possible, but commercially feasible. This groundbreaking technology, developed by Methode's Sensor Technology group, has also made vehicle electrically assisted-compliant steering a reality. Methode's patented magnetoelastic technology allows custom-designed solutions to meet any customer or industry needs.

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Customer Values

  • Maintenance-free throughout the design life of the product
  • Enhanced product performance and design-in simplicity
  • Product differentiation
  • Reduce warranty and catastrophic failure
  • Achieve ever-changing industry and regulatory requirements

Technology Values

  • No sensor wear or recalibration throughout the design life
  • Total immersion in caustic fluids, high temperature, impact and vibration
  • Meet challenging ergonomic, environmental performance and cost objectives

Technology Fundamentals

Methode's patented non-contact sensor technology utilizes fundamental mechanical and magnetic properties of the material to measure different process parameters. The process involves measuring changes in the properties of remnant magnetic fields as the mechanical characteristics change, such as shear stress, as external forces are applied onto the sensor host. The technology is applied by directly magnetizing a mechanical member instead of attaching additional elements, such as a ring. Highly sensitive fluxgate sensors located in close proximity to the magnetized member sense the change in the magnetic-field characteristics that are proportional to the applied force. These changes are linear and repeatable within the elastic limit of the material, and are accurate under normal and extended operating conditions. Even though the underlying principle utilizes the theory of magnetoelasticity, Methode enhances the efficiency by developing and patenting magnetic profiles that eliminate certain known shortcomings of magnetoelasticity, increasing its versatility and uses.

Solution Line Capabilities

Torque

Torque measurement has been previously achieved primarily through either a strain gauge or phase-shift approach, which limited the applications for engineers and required mathematical solutions to estimate torque. Methode now provides a commercially viable measurement of torque either in an axial or radial direction. Methode's magnetoelastic technology can function on any size substrate whether it is rotating at high speeds or not at all. Through patented enhancements to the fundamental magnetoelastic technology, Methode can now provide robust measurements without the use of costly shielding for challenging EMI conditions and maintain very high accuracy. Typically this measurement is used as a discrete input or as a critical measurement for closed-loop control within a larger system.

COMMON SPECIFICATIONS

Range: 0 to +/- 1Nm or 0 to +/- 50 kNm
Resolution: 0.1 Nm to 0.5 Nm
Accuracy: 0.5% to 1.0%
Repeatability: 0.25% to 0.4%
Response to Change: 1kHz to 20kHz
Substrate: 6.0mm to 600mm
Operating Temperature: -40C to 180C
Power Required: <15mA

Linear Position

Methode's magnetoelastic technology offers a new approach that addresses previously ignored or difficult to overcome application challenges for engineers. The key to our patented approach of measuring linear position is in the sensing device, which magnetically conditions the shaft with a low-level profile that is then measured by a very sensitive fluxgate assembly. The integration of current magnetics into the equipment make our sensors a more cost-effective solution. This sensor assembly also features a low profile that allows for ease of integration, and often avoids necessary rework of current equipment designs. Additionally, because of Methode's magnetic profile, our solutions can reside within caustic fluids and not draw ferrous material towards the sensor, which eliminates additional engineering efforts to isolate the shaft and or sensor from the fluids.

COMMON SPECIFICATIONS

Range: <1 mm to 33 mm
Resolution: 0.1 mm to 0.5 mm<
Accuracy: 0.5% to 1.0%
Repeatability: 0.25% to 0.4%
Response to Change: 1kHz to 20kHz
Substrate: 6.0mm to 600mm
Operating Temperature: -40C to 180C
Power Required: <15mA

Speed

Magnetizing the shaft, target or gear tooth allows for the measurement of speed without applying a permanent target to the shaft. Methode's sensor offers a small footprint, an easy design installation; the ability to measure through a nonferrous membrane or wall, such as a housing; and can be placed in potentially explosive environments. A simple two-wire connection provides a commonly accepted signal output. The greater value is when the speed sensor is incorporated as part of a torque or absolute-angle sensor. The magnetic profile and housing then becomes common, mitigating the cost of two or three different devices, and reducing space, weight and customer product assembly.

COMMON SPECIFICATIONS

Range: <1 rpm to 25,000 rpm
Resolution: 0.1 rpm
Accuracy: 0.5% to 1.0%
Repeatability: 0.25% to 0.4%
Response to Change: 1kHz to 20kHz
Operating Temperature: -40C to 180C
Power Required: <15mA

Absolute Angle

The ability to measure absolute angular position without the use of an applied mechanical target improves accuracy and reduces requirements usually placed on engineers. A magnetic profile is applied to the rotating shaft, and the sensor device then measures the profile's changes. As this is an analog measurement, response times can be rapid, which allows for use at high rotational speeds, but can be changed to a digital signal if the customer desires. This technology offers significant value in measurement resolution, robustness, rapid response, ease of integration and commercial viability. Like speed sensors, real value in design comes from the ability to combine absolute angle, torque and speed into one sensor—offering the engineer a real space and cost savings, as well as performance enhancement.

COMMON SPECIFICATIONS

Range: 0.1 degree to 360 degrees
Resolution: 1 degree to 4 degrees
Accuracy: 0.5% to 1.0%
Repeatability: 0.25% to 0.4%
Response to Change: 1kHz to 20kHz
Operating Temperature: -40C to 180C
Power Required: <15mA

Load & Force

Methode's patented approach is the first technology that is durable enough to withstand extreme temperature changes, as well as overload excursions without damage to the sensor. The sensor never drifts over time or requires recalibration, offering a stable solution throughout the product's life. Methode's magnetoelastic technology also allows for use in washdown applications and in environments that require special certifications, including explosion-proof and submersible in nonconductive fluids. Our custom design offers installation into areas that present hurdles to other technologies.

COMMON SPECIFICATIONS

Range: <1 lbs to 20 tons
Resolution: 0.25 lbs to 1 lbs
Accuracy: 0.5% to 1.0%
Repeatability: 0.25% to 0.4%
Response to Change: 1kHz to 20kHz
Substrate: 6.0mm to 600mm
Operating Temperature: -40C to 180C
Power Required: <15mA

Level

Methode's magnetoelastic technology offers a safe and reliable approach to those applications where the material is flammable or requires special handling. The measurement can be made through the wall of the container or nonferrous pipe or housing. This allows sensor pickups and electronics to reside outside the vessel. For those applications where it is desired to have the sensor submerged in the fluid, Methode's magnetoelastic technology survives most caustic environments. Baseline benefits of the technology allow for creative approaches.

COMMON SPECIFICATIONS

Range: application specific
Resolution: application specific
Accuracy: 0.5% to 1.0%
Repeatability: 0.25% to 0.4%
Response to Change: 1kHz to 20kHz
Operating Temperature: -40C to 180C
Power Required: <15mA

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