Differential Ring Gear Speed Target for Hybrid Gearbox Sensing
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Solution Overview
Problem
Existing motor vehicle transmission differential systems face challenges in accurately and reliably measuring the speed of rotation of the ring gear, particularly in hybrid transmissions where precise control of power sources and synchronization of shaft speeds are crucial, while ensuring the design and location of measurement targets do not disrupt lubrication or housing functionality.
Innovation Solution
A motor vehicle transmission differential ring gear design featuring a measurement target arranged on the radial side face of the crown with a peripheral annular body and a machined housing, where the target is axially force-fitted, allowing for precise speed measurement using a sensor positioned either axially or radially opposite the target teeth, ensuring compatibility with a parking wheel and locking mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring target with sufficient number of teeth is used to provide accurate differential regime measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measuring target is segmented into two functional parts: the crown with gear teeth for mechanical engagement and parking wheel cooperation, and the integrated target portion with distributed teeth for measurement. This segmentation allows each part to optimize its function while reducing overall complexity.
Solution Approach 2:
The measuring target merges multiple functions into a single integrated component: it serves as both the gear crown for power transmission and the measurement target for speed sensing. The target portion is directly formed as part of the crown, eliminating the need for separate attached targets and reducing assembly complexity.
2Ease of operation
If the measuring target is placed on the differential housing, then ease of operation is improved, but it impacts the parking wheel placement and lubrication function
Solution Approach 1:
The measuring target is positioned on the crown's outer peripheral surface, utilizing the radial dimension rather than occupying the axial space on the housing. This dimensional relocation allows the parking wheel to be placed on the housing without interference, while the target remains accessible to sensors through the radial arrangement of its teeth.
Solution Approach 2:
The target is located specifically on the crown's outer peripheral surface, a local position that does not interfere with the housing's lubrication channels or the parking wheel's mounting area. This localized placement maintains the housing's full functionality while enabling measurement.
3Device complexity
If the sensor is positioned inside the gearbox casing, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The target's teeth are asymmetrically distributed around the crown's periphery, creating an irregular pattern as the crown rotates. This asymmetric tooth distribution ensures that sensors positioned at various locations inside the gearbox casing can detect the rotational position and speed accurately, as the asymmetric pattern provides unique positional information at each angle.
Data Source
AI summary
The invention relates to a differential ring gear (22) comprising gear teeth arranged along the outer radial periphery thereof, characterised in that the differential ring gear is equipped with a target (50) for measuring the rotation speed of the differential ring gear, said target taking the form of a ring comprising a plurality of circumferentially distributed teeth (56). The measurement target (50) is arranged on a radially oriented side face of the differential ring gear (12).