Vehicle Transmission Speed Sensor Using Drain Plug Integration
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Solution Overview
Problem
The compact nature of modern vehicles and variety of transmission models make it challenging to select a suitable location for an additional threaded hole required by traditional electronic speed sensors in vehicle transmissions, increasing manufacturing costs and reducing reliability due to susceptibility to vehicle suspension movement.
Innovation Solution
Integrating a tone wheel with equispaced radial arms on a rotating output element and using an inductive pick-up, such as a drain, fill, or level plug, to eliminate the need for an additional threaded hole and ensure access without extra measures, providing a reliable speed signal closer to the microprocessor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional threaded hole is provided in the transmission casing for a traditional electronic speed sensor, then speed sensing capability is improved, but manufacturing cost increases and the location selection becomes problematic due to compact vehicle design
Solution Approach 1:
The patent combines the speed sensing function with an existing threaded hole in the transmission casing that is already required for other purposes (such as mounting brackets or covers). By integrating the speed sensor into this pre-existing hole, the patent eliminates the need to create an additional hole, thereby avoiding extra manufacturing steps and reducing production costs while maintaining speed sensing capability
Solution Approach 2:
The patent makes the existing threaded hole serve multiple functions: its original purpose (such as mounting support) and the new speed sensing function. This multi-functionality approach allows the same structural feature to fulfill both its traditional role and the speed detection role, eliminating the need for dedicated separate provisions
2Reliability
If an additional threaded hole is provided in the transmission casing for a traditional electronic speed sensor, then speed sensing capability is improved, but device complexity increases due to additional access space requirements
Solution Approach 1:
The patent merges the speed sensor mounting location with an existing access point in the transmission casing. By placing the speed sensor in a hole that already requires access for other maintenance or assembly purposes, the patent avoids creating additional access spaces, thereby reducing structural complexity and simplifying the overall design
3Reliability
If a wheel hub speed sensor is used, then speed indication is provided, but the sensor is subject to vehicle suspension movement which reduces reliability
Solution Approach 1:
The patent extracts the speed sensing function from the wheel hub location (which is subject to suspension movement) and relocates it to the transmission casing (which is a fixed, stable structure). By taking the sensor out of the vulnerable wheel hub environment and placing it in the stable transmission housing, the patent eliminates the harmful effect of suspension movement on sensor reliability
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 solution reduces manufacturing costs, ensures reliable speed sensing by utilizing existing transmission casing holes, and provides a stable speed signal for vehicle systems like tachographs, while being less susceptible to suspension movement.
Implementation Method 1
an inductive pick-up comprising one of a drain plug, a fill plug or a level plug of a transmission casing
Data Source
AI summary
A speed sensor of a rotatable output element of a transmission comprises a rotating tone wheel (33) and an inductive pick-up (29) comprising one of a drain plug, a fill plug or a level plug. The arrangement is suitable for providing a vehicle speed signal to a vehicle tachograph.