Split Secondary Gear with Spring Preload for Backlash-Free Angle Sensing
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Solution Overview
Problem
Gear arrangements for detecting and transmitting the angle of rotation of a rotatable shaft, particularly in steering angle sensor devices, face issues with hysteresis, wear, and rattling noises due to elasticity and temperature fluctuations, leading to inaccurate steering column module performance.
Innovation Solution
A gear wheel arrangement featuring a main rotor and a secondary rotor connected by a spiral spring with a bending angle of zero degrees, allowing for play-free transmission of rotational movement while reducing the risk of distortion and wear, using involute gearing and congruent tooth geometry to ensure backlash-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gear arrangements are used to transmit rotational movement, then the structure is simple, but hysteresis and backlash occur due to elasticity and temperature fluctuations leading to inaccurate detection
Solution Approach 1:
The gear wheel is divided into multiple identical tooth sections (first tooth section, second tooth section, etc.) arranged symmetrically around the gear circumference. Each tooth section has congruent geometry with the others, allowing the gear to be segmented into functional units that work in parallel to reduce hysteresis effects
Solution Approach 2:
The invention changes the geometric parameters of the gear teeth by using involute tooth profiles with specific pressure angles (20° or 15°) and ensuring congruent tooth geometry across all tooth sections. This parameter optimization minimizes backlash and hysteresis while maintaining smooth transmission
2Ease of manufacture
If gear teeth with standard geometry are used, then manufacturing is easy, but wear and rattling noises occur due to backlash changes from elasticity and temperature
Solution Approach 1:
The gear teeth are designed with specific involute profile parameters including pressure angles of 20° or 15°, and all tooth sections have congruent geometry with identical addendum, dedendum, and tooth thickness. These optimized parameters minimize backlash variations under thermal and elastic conditions, reducing wear and noise while remaining manufacturable
Solution Approach 2:
The gear is pre-designed with compensation features for thermal expansion and elastic deformation by using symmetric tooth arrangement and congruent geometry. This preliminary design accounts for temperature fluctuations and elasticity effects before operation, preventing excessive backlash changes that cause noise and wear
3Measurement precision
If multiple auxiliary rotors are added to improve detection accuracy, then rotation angle measurement improves, but device complexity increases
Solution Approach 1:
Instead of using multiple complex auxiliary rotors, the invention segments a single auxiliary rotor into multiple identical tooth sections that function independently but symmetrically. This segmentation achieves the same measurement redundancy and accuracy improvement as multiple rotors would provide, but with significantly reduced structural complexity
Solution Approach 2:
The invention merges the functions of multiple auxiliary rotors into a single auxiliary rotor by placing multiple identical tooth sections on the same rotor body. This consolidation maintains the measurement precision benefits of having multiple measurement paths while eliminating the mechanical complexity of multiple separate rotor assemblies
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 enables accurate, hysteresis-free transmission of rotational angles over a large operating range, improving the accuracy and reducing wear and noise in steering angle sensor devices.
Implementation Method 1
Due to elasticity within the gear drive and/or temperature fluctuations, backlash can develop between the individual gears
Implementation Method 2
A gear wheel arrangement featuring a main rotor and a secondary rotor connected by a spiral spring with a bending angle of zero degrees
Implementation Method 3
A gear wheel arrangement featuring a main rotor and a secondary rotor connected by a spiral spring with a bending angle of zero degrees, allowing for play-free transmission of rotational movement while reducing the risk of distortion and wear, using involute gearing and congruent tooth geometry
Data Source
Figure 1
Figure 2~3
Figure 4~5b
AI summary
The invention relates to a gear arrangement and a sensor device for detecting the angle of rotation of a rotatable shaft, wherein the gear arrangement comprises at least one main rotor (2) with teeth that can be connected to the shaft in a rotationally synchronous manner, at least one secondary rotor (3) with teeth that is mechanically coupled to the main rotor by a first transmission, and at least one spring element, wherein the teeth of the main rotor (2) mesh with the teeth of the secondary rotor (3), wherein the secondary rotor (3) has at least two gears (Z1, Z2) arranged parallel to each other, each of which meshes with the teeth of the main rotor (2), wherein the at least two gears (Z1, Z2) of the secondary rotor (3) are rotatable relative to each other, wherein the at least two gears (Z1, Z2) of the secondary rotor (3) are coupled to each other by means of the at least one spring element, and wherein the at least one spring element is a straight bending spring.which has a bending angle of zero degrees (0°) in a stress-free state.