Sensor Gear With Segmented Teeth For Steering Position Measurement
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Solution Overview
Problem
Current position detection assemblies for steering shafts in power steering systems face challenges in accurately measuring rotational position and torque, leading to inefficiencies in power steering assist delivery.
Innovation Solution
A sensor module with a unique gear design, featuring a first gear with radially extending teeth and slots, and a flexible tooth configuration that maintains double flank contact with driving gears, enabling precise measurement of angular position and torque through a sensor assembly connected to a power steering assist unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional gear assembly is used in the sensor module, then the structure is simpler, but the measurement precision of rotational position and torque deteriorates
Solution Approach 1:
The gear tooth is segmented into multiple portions (first tooth portion, second tooth portion, third tooth portion) with different functional characteristics. Each portion is optimized for specific purposes: the first tooth portion maintains double flank contact for precise position measurement, the second tooth portion provides structural support, and the third tooth portion engages with the driving gear. This segmentation allows the gear assembly to achieve high measurement precision while managing structural complexity through functional differentiation.
Solution Approach 2:
Different regions of the gear tooth are given different geometric properties and material characteristics. The first tooth portion has specific flank angles and surface finishes optimized for sensor contact and position measurement, while other portions have properties optimized for strength and engagement. This local quality differentiation enables precise measurement without requiring the entire gear structure to be overly complex.
2Reliability
If the gear tooth width is uniform throughout, then the manufacturing is easier, but the reliability of double flank contact deteriorates at varying center distances
Solution Approach 1:
The gear tooth width parameter is changed along the radial direction, creating a tapered or variable width profile. The first tooth portion has a different width than the second and third portions, allowing the contact surfaces to maintain proper alignment and double flank contact reliability even when center distances vary during operation. This parameter variation compensates for manufacturing tolerances and assembly variations.
Solution Approach 2:
The variable tooth width design allows the gear to dynamically adapt to varying center distances during operation. As the center distance changes, the different width portions engage differently, maintaining reliable double flank contact throughout the range of motion. This dynamic adaptation ensures consistent measurement reliability without requiring precision manufacturing at the expense of ease of manufacture.
3Adaptability or versatility
If the first slot extends deeply towards the slot root, then the flexibility for de-lashing improves, but the structural strength of the gear tooth deteriorates
Solution Approach 1:
The gear tooth is segmented into multiple portions separated by slots of different depths. The first slot extends partially towards the root to provide flexibility for de-lashing operations, while the second slot provides additional flexibility. This segmentation allows the tooth to bend and flex during de-lashing without compromising overall structural strength, as the remaining tooth portions maintain structural integrity.
Solution Approach 2:
Different portions of the gear tooth have different structural qualities and slot configurations. The first tooth portion has a slot that provides localized flexibility for de-lashing, while the second and third portions maintain stronger, more rigid structures for load-bearing and engagement. This local quality differentiation allows the gear to have both flexibility where needed and strength where required.
Data Source
AI summary
A gear includes a gear body and a first gear tooth. The gear body extends radially between an outer portion and an inner portion. The first gear tooth has a first tooth portion, a second tooth portion, and a first slot. The first tooth portion extends radially from the outer portion towards a first land. The second tooth portion is circumferentially spaced apart from the first tooth portion and extends radially from the outer portion towards a second land. The first slot is defined between the first tooth portion and the second tooth portion and extends from at least one of the first land and the second land towards a first slot root.