Driveshaft Torque Sensor Using Magnetic Encoding
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Solution Overview
Problem
Existing driveshaft torque sensors are expensive, leading to a desire for a more economical solution that can accurately measure torque transmission in motorized vehicles.
Innovation Solution
A driveshaft assembly with a magnetically encoded zone on a nickel-alloy steel shaft member, coupled with a bearing assembly and sensor system that senses the magnetic field changes to produce an electrical signal for torque measurement, allowing for accurate calculation of vehicle horsepower and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque sensor such as a strain gage or surface acoustic wave device is used to directly measure shaft torque, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent replaces traditional mechanical torque sensors (strain gages, surface acoustic wave devices) with a magnetic field-based sensing system. A magnetically encoded zone is created on the driveshaft, and a magnetic sensor detects changes in the magnetic field as the shaft rotates, converting mechanical torque measurement into a magnetic field detection problem. This substitution eliminates the need for expensive mechanical sensors while maintaining measurement capability.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the torque applied to the driveshaft and the sensor detection. The magnetically encoded zone acts as a mediator that translates mechanical torque into detectable magnetic field variations. This intermediary approach allows indirect measurement of torque through magnetic field changes, providing a cost-effective alternative to direct mechanical sensing.
2Ease of manufacture
If approximation techniques are used to estimate torque magnitude, then device cost is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces approximation techniques with a direct magnetic field-based measurement system. By creating a magnetically encoded zone on the driveshaft and using a magnetic sensor to detect field changes, the system achieves actual torque measurement rather than estimation. This substitution maintains low cost while eliminating the precision limitations of approximation methods.
Solution Approach 2:
The driveshaft itself serves as part of the sensing system through the magnetically encoded zone. The shaft's own rotation and torque transmission properties are utilized to generate the magnetic field variations that the sensor detects. This self-service approach eliminates the need for separate, expensive sensing mechanisms while providing accurate measurement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective means to directly measure torque transmission, offering accurate performance data and enabling better control over vehicle operations, including shift points and early diagnostics for driveline issues.
Implementation Method 1
a magnetically encoded zone with a magnetic field that varies as a function of the torque that is transmitted through the first shaft member
Implementation Method 2
The sensor is arranged to sense the magnetic field of the magnetically encoded zone and responsively produce an electrical signal
Data Source
AI summary
A driveshaft assembly that includes a first shaft member, a second shaft member, a bearing assembly and a sensor. The first shaft member has a magnetically encoded zone with a magnetic field that varies as a function of the torque that is transmitted through the first shaft member. The second shaft member is coupled for rotation with the first shaft member. The bearing assembly comprises a bearing support, which is configured to be coupled to a vehicle structure, and a bearing that is housed in the bearing support. The bearing journally supports the first shaft member for rotation about a first axis. The sensor is coupled to the bearing assembly. The sensor is arranged to sense the magnetic field of the magnetically encoded zone and responsively produce an electrical signal.