Steering Angle Sensor with Non-Volatile Revolution Counter
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Solution Overview
Problem
Existing steering angle sensors require multiple components and signal lines to detect the steering angle over a range of angles greater than 360°, making them complex and inefficient, especially when used as True Power On Sensors that need to function without electrical energy for extended periods.
Innovation Solution
A steering angle sensor design that uses a transmitter element and a measuring sensor to generate a magnetic field, with a counting element and non-volatile memory to count revolutions, allowing for a single signal line to determine the absolute angular position, and incorporating magnetizable memory elements connected in series to achieve a counting effect, enabling the sensor to operate without electrical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transmitter elements and measuring sensors are used to detect steering angle over multiple revolutions, then the detection accuracy and range are improved, but the device complexity and number of components increase
Solution Approach 1:
The patent combines multiple transmitter elements and measuring sensors into a single integrated unit. The transmitter element generates a magnetic field that is detected by the measuring sensor, and both are coupled to the same evaluation unit, reducing the number of separate components while maintaining the capability to detect steering angle over multiple revolutions through signal processing
Solution Approach 2:
The single transmitter element and measuring sensor configuration is designed to perform multiple functions: detecting steering angle within one revolution and counting revolutions over multiple turns. The evaluation unit processes signals to determine both the angular position and the number of revolutions, making the sensor system multi-functional without requiring additional components
2Measurement precision
If a mechanical gearbox is used to determine absolute angular position over multiple revolutions, then the detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical gearbox with an electromagnetic field-based system. The transmitter element generates a magnetic field that rotates with the steering column, and the measuring sensor detects this field to determine angular position. The evaluation unit processes the magnetic field signals to calculate both the angular position within one revolution and the number of revolutions, eliminating mechanical complexity while maintaining detection capability
Solution Approach 2:
The system uses changes in magnetic field parameters (strength, direction, phase) as the transmitter element rotates to encode both the angular position and revolution count information. The evaluation unit detects these parameter changes and translates them into absolute angular position data over multiple revolutions, replacing mechanical position encoding with electromagnetic parameter modulation
3Use of energy by moving object
If the sensor is designed as a True Power On Sensor to function without electrical energy, then the energy efficiency is improved, but the reliability of data retention may worsen
Solution Approach 1:
The sensor system uses the rotational motion of the steering column itself to generate the magnetic field through the transmitter element, eliminating the need for external electrical power during normal operation. The measuring sensor detects the magnetic field generated by the transmitter element's position, and the evaluation unit processes this passive signal to determine steering angle and revolution count, making the system self-powered during operation
Solution Approach 2:
The system is designed to retain revolution count data in memory before power is applied, allowing the sensor to function as a True Power On Sensor. The non-volatile memory stores the revolution count information persistently, so when power is first applied or after extended periods without power, the system can immediately access the stored revolution data without requiring re-initialization or continuous power
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
This design simplifies the sensor by reducing the number of components needed, allowing it to function as a True Power On Sensor and accurately detect steering angles over multiple revolutions, even without electrical energy, while enhancing the detection of steering torque and driver intention for vehicle assistance systems.
Implementation Method 1
a transmitter element for exciting a transmitter field and a measuring sensor for stimulating an output signal depending on the reception of the transmitter field
Implementation Method 2
the non-volatile memory comprises at least two magnetizable memory elements that are connected together in series, the magnetization of which can be adjusted by a magnetic source depending on the number of revolutions of the transmitter field
Implementation Method 3
a magnetoresistive measuring sensor based on the AMR effect, the TMR effect or the GMR effect
Data Source
AI summary
The invention relates to a steering angle sensor for detecting a steering angle of a steering column over an angular range of more than 360° in a vehicle, comprising—a transmitter element for exciting a transmitter field and a measuring sensor for exciting an output signal dependent on a reception of the transmitter field, wherein the measuring sensor and the transmitter element are arranged such that the transmitter field received by the measuring sensor is dependent on the steering column rotational angle to be detected, and—a counter element with a non-volatile storage unit for counting and outputting a number of revolutions of the transmitter field with respect to a reference rotational angle.