Automatic Gearbox Downshift Control via Actuator and Brake Signals
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Solution Overview
Problem
Existing control devices for automatic gearboxes in sporty vehicles lack the ability to securely alternate between single downshift and multiple downshift modes, often resulting in unintended multiple downshifts due to prolonged actuator pressing, and do not optimize gear change sequences, potentially taking the driver by surprise.
Innovation Solution
A control device with an electronic control unit that detects actuator and brake pedal signals to differentiate between single and multiple downshift requests based on time delays, ensuring safe gear changes within engine speed limits, and calculates the minimum transmission ratio for multiple downshifts based on vehicle speed and current gear engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If prolonged pressing on the actuator is used to trigger multiple downshifts, then the driver can quickly change to lower gears for sporty driving, but unintended multiple downshifts may occur that surprise the driver
Solution Approach 1:
The brake pedal acts as an intermediary condition that must be simultaneously activated with the actuator to trigger multiple downshifts. This additional mediator prevents accidental activation while preserving quick gear changes when intentionally desired, resolving the contradiction between speed and reliability
Solution Approach 2:
The control system adds a temporal dimension by requiring simultaneous activation of two controls (actuator + brake pedal) within a specific time window. This transforms a simple pressure-duration control into a multi-dimensional control scheme that prevents unintended operations
2Reliability
If downshifts are performed one by one with time delays, then safety checks can be performed at each step, but the gear change sequence is not optimized and takes longer
Solution Approach 1:
The control unit pre-calculates the optimal downshift sequence and identifies the final target gear before execution. By determining the complete path in advance and performing safety checks proactively, the system enables faster sequential downshifts without compromising safety, reducing total gear change time
3Speed
If multiple downshifts are executed quickly, then the driver experiences responsive gear changes, but the engine speed may exceed authorized limits
Solution Approach 1:
The control unit continuously monitors engine speed during the downshift sequence and uses feedback to adjust the timing and progression of gear changes. This real-time feedback ensures that engine speed remains within authorized limits while maintaining responsive gear changes, resolving the contradiction between speed and harmful effects
Data Source
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AI summary
The device comprises an electronic control unit (10) that can detect a request from a driver to perform a single or multiple downshift. The control unit receives a first boolean signal (BR) associated with brake pedal (6) pressure and a second boolean signal (PAD) associated with pressure on a spring-back actuator (7), and the control unit delivers a third boolean signal requesting a single downshift (Mono_R) and a fourth boolean signal (Multi_R) requesting a multiple downshift. The electronic control unit (10) triggers a time delay when the actuator is activated and maintains same as long as the actuator is activated.