Acceleration-Based Binary Clutch Control for Smooth Gear Shifts
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Solution Overview
Problem
Binary clutch assemblies in vehicle transmissions face challenges in smoothly transitioning between gear states, particularly during high-acceleration launches and rolling garage shifts, due to their binary nature with only fully-applied and fully-released states, which can lead to inefficient shifts and potential delays in gear changes.
Innovation Solution
A controller communicates with the binary clutch assembly and vehicle speed sensors to calculate vehicle acceleration and select a variable shift apply point, dynamically switching the SOWC portion from a locked to a freewheeling state based on acceleration, allowing for smoother transitions between gear states, such as from 1st gear to 2nd gear and enabling reverse shifts during rolling garage maneuvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the SOWC portion is kept in applied state during 1st gear launch, then the binary clutch assembly can enable rolling garage shift to reverse, but it prevents smooth shift to 2nd gear
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed shift apply point to a dynamic variable shift apply point that adapts based on vehicle acceleration. The controller monitors acceleration and adjusts the shift apply point in real-time, allowing the SOWC portion to remain applied longer during high acceleration (enabling reverse shifts) while automatically releasing earlier during low acceleration (enabling smooth 1-2 shifts).
Solution Approach 2:
The patent changes the parameter of shift apply point from a fixed value to a variable value that depends on acceleration. By making the shift apply point a function of acceleration rather than a constant, the system can optimize clutch engagement timing for different driving conditions, resolving the contradiction between reverse shift capability and smooth forward shifting.
2Ease of operation
If the SOWC portion is released early for smooth 1st to 2nd gear shift, then forward gear transitions improve, but the ability to shift to reverse during rolling garage maneuvers is lost
Solution Approach 1:
The system dynamically adjusts the SOWC release timing based on real-time acceleration feedback. During high acceleration launches, the controller maintains the SOWC in applied state longer, preserving reverse shift capability. During low acceleration conditions, the controller releases the SOWC earlier, enabling smooth 1-2 shifts. This dynamic adaptation resolves the contradiction.
Solution Approach 2:
The patent implements feedback control by continuously monitoring vehicle acceleration and using this information to determine the optimal shift apply point. The acceleration signal provides feedback about driver intent and vehicle state, allowing the controller to make informed decisions about SOWC timing that balance both reverse shift capability and smooth forward shifting.
3Device complexity
If a fixed shift apply point is used, then control is simple, but it cannot accommodate varying acceleration conditions and driver intent
Solution Approach 1:
The patent changes the shift apply point parameter from fixed to variable based on acceleration. This allows the system to adapt to different driving conditions while maintaining a relatively simple control structure. The acceleration-based variable shift apply point provides the necessary adaptability without requiring complex control algorithms.
Data Source
AI summary
A vehicle includes an engine and transmission having gear sets, an input member that is continuously connected to the engine and a gear set, a binary clutch assembly, a speed sensor, and a controller. The binary clutch assembly includes a freewheeling element holding torque in one rotational direction, and also a selectable one-way clutch (SOWC) portion holding torque in two rotational directions when applied. The controller executes a method to transmit a first binary clutch command to the binary clutch assembly and thus apply the SOWC portion at vehicle launch, and calculates, via the processor, an acceleration value of the vehicle using the measured speed. The controller also selects a shift apply point of the binary clutch assembly as a function of the calculated acceleration value, and transmits a second binary clutch command to the binary clutch assembly to release the SOWC portion at the selected shift apply point.