Non-Contact Torque Sensor Using Millimeter Wave Encoder Structures
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Solution Overview
Problem
Conventional torque sensors face issues such as reduced lifetime due to abrasion, high costs, and increased complexity, particularly in the automotive industry, where mechanical contact and magnetic field applications lead to frictional resistance, high costs, and reduced measurement precision.
Innovation Solution
A device utilizing two encoder structures coupled to a shaft for conjoint rotation, with a transmitter and receiver configured to transmit and receive millimeter waves, allowing for the determination of torque by analyzing the relative rotation of the encoder structures, thereby reducing friction and complexity while enhancing measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistance potentiometer with mechanical contact is used for torque measurement, then the sensor can detect torque through contact position changes, but the frequent rotation leads to abrasion that considerably reduces the lifetime of the sensor
Solution Approach 1:
The patent replaces the mechanical contact-based resistance potentiometer with a magnetic field-based detection system. The encoder structure with magnetic poles interacts with a magnetic sensor without physical contact, eliminating wear and extending sensor lifetime while maintaining torque measurement capability through detection of magnetic field changes caused by encoder disk rotation.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the rotating shaft and the stationary sensor. The encoder disk with magnetic poles modulates the magnetic field, which is then detected by the magnetic sensor, allowing torque measurement without direct mechanical contact between moving and stationary components.
2Measurement precision
If a resistance potentiometer with friction contact is used for torque measurement, then the sensor can detect torque through contact position changes, but the frictional resistance causes power deficiency during operation
Solution Approach 1:
The patent replaces the friction-based mechanical contact system with a non-contact magnetic field detection system. The magnetic sensor detects changes in the magnetic field generated by the encoder disk, eliminating frictional resistance and the associated power loss while maintaining accurate torque measurement.
3Measurement precision
If a resistance potentiometer with multiple components is used for torque measurement, then the sensor can detect torque through contact position changes, but the transition process from torque to electrical signal comprises many links and components, entailing high costs
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate components from the torque-to-electrical-signal conversion process. By using a magnetic encoder disk with magnetic poles that directly modulate the magnetic field detected by a magnetic sensor, the system removes the need for resistive elements, sliding contacts, and complex signal conditioning circuits, thereby reducing component count and cost.
Solution Approach 2:
The patent replaces the complex mechanical-resistive signal conversion mechanism with a simpler magnetic field-based detection system. The encoder disk's rotational position directly modulates the magnetic field, which is detected by the magnetic sensor, eliminating multiple mechanical links and reducing overall system complexity.
4Use of energy by moving object
If a coiled cable is provided for electrical supply to the torque sensor on the rotating shaft, then the sensor can be electrically supplied, but the cable limits the number of revolutions
Solution Approach 1:
The patent replaces the electrical supply system with a wireless power transmission system using electromagnetic induction. A transmitter on the rotating shaft transfers power wirelessly to a receiver on the stationary housing, eliminating the coiled cable and its revolution limit while providing continuous electrical supply to the sensor.
5Adaptability or versatility
If wireless energy supply by inductive coupling is used for torque sensor power transmission, then the cable revolution limit is eliminated, but this considerably increases complexity, structural space and costs
Solution Approach 1:
The patent combines the wireless power transmission function with the existing magnetic field detection system. The same magnetic coupling mechanism used for torque measurement is also utilized for wireless power transfer, allowing the encoder disk and magnetic poles to serve dual functions: encoding rotational information and enabling inductive power transmission, thereby reducing overall system complexity.
6Measurement precision
If magnetic field sensors are used for detecting position change in torque sensors, then the sensor can detect torque through magnetic field changes, but the magnetic field applications cause additional costs on the application side
Solution Approach 1:
The patent introduces an encoder disk with magnetic poles as an intermediary that converts rotational position into a modulated magnetic field pattern. This allows the use of simple, cost-effective magnetic sensors on the stationary side to detect torque, while the expensive magnetic field generation components (magnetic poles and encoder disk) are located on the rotating shaft where they are already required for 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 effectively reduces sensor costs and improves performance by eliminating mechanical contact and magnetic field dependencies, enabling precise torque measurement with reduced friction and increased sampling rate.
Implementation Method 1
at least one transmitter configured to transmit millimeter waves (mm waves) in the direction of the first and second encoder structures and at least one receiver configured to receive mm waves reflected or transmitted by the first and second encoder structures
Data Source
AI summary
A concept for torque measurement on a shaft is described. To that end, millimeter waves are transmitted in the direction of a first encoder structure, which is coupled to a first shaft section of the shaft for conjoint rotation and is arranged around the shaft, and in the direction of a second encoder structure, which is coupled to a second shaft section of the shaft for conjoint rotation and is arranged around the shaft. The first encoder structure and the second encoder structure are rotatable relative to one another in the case of a torque to be transmitted via the shaft. At least one reception signal is generated on the basis of millimeter waves reflected or transmitted by the first and second encoder structures. A torque transmitted using the shaft is determined on the basis of the at least one reception signal.