Transmission Clutch Hold Pressure Control for Hill Ascent and Descent
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Solution Overview
Problem
Existing transmission control systems struggle to effectively manage clutch hold pressure to prevent roll-back or roll-forward of vehicles when traversing inclines or declines, particularly during initial acceleration from a stationary or near-stationary position, as they rely on simplistic braking torque adjustments and lack precise control based on vehicle tractive effort and road grade.
Innovation Solution
A transmission control module that determines and applies clutch hold pressure based on a combination of transmission output speed, throttle position, brake status, and road grade, using a control circuit with stored instructions to calculate tractive effort and adjust clutch pressure dynamically to resist roll-back or roll-forward, incorporating sensors for real-time data and threshold comparisons to optimize clutch engagement and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simplistic braking torque adjustments are used in existing transmission control systems, then the system complexity is reduced, but the ability to effectively manage clutch hold pressure to prevent roll-back or roll-forward on inclines is insufficient
Solution Approach 1:
The clutch hold pressure is dynamically adjusted based on real-time vehicle conditions including tractive effort calculations, road grade detection, transmission output speed, throttle position, and brake status. The control system continuously modifies the clutch hold pressure rather than using fixed simplistic adjustments, allowing the system to adapt to changing conditions while maintaining reliable roll-back prevention.
Solution Approach 2:
The transmission control module implements a feedback mechanism that monitors multiple parameters (transmission output speed, throttle position, brake status, road grade) and uses this information to continuously adjust the clutch hold pressure. The system compares actual vehicle conditions against desired states and modifies clutch pressure accordingly to maintain effective control on inclines.
2Stability of the object's composition
If clutch hold pressure is increased to resist roll-back on inclines, then vehicle stability is improved, but the risk of clutch slippage and excessive wear increases
Solution Approach 1:
The control system dynamically changes the clutch hold pressure parameter based on calculated tractive effort, road grade, and vehicle conditions. Rather than applying maximum constant pressure, the system adjusts the pressure to the minimum level required to prevent roll-back, thereby maintaining vehicle stability while minimizing clutch slippage and wear through optimized parameter selection.
Solution Approach 2:
The system applies partial action by using only the necessary amount of clutch hold pressure required to prevent roll-back rather than excessive pressure. The clutch hold pressure is modulated to match the actual demand based on tractive effort calculations, providing just enough force to maintain stability without causing harmful slippage or accelerated wear.
3Productivity
If clutch release ramp rate is increased for faster acceleration response, then productivity is improved, but the risk of vehicle roll-back before clutch engagement increases
Solution Approach 1:
The system performs preliminary action by establishing the required clutch hold pressure before clutch release begins. The transmission control module calculates the necessary hold pressure based on tractive effort and road grade, then applies this pressure in advance of clutch engagement. This preliminary positioning of the clutch under proper pressure ensures the vehicle remains stable before acceleration commences.
Solution Approach 2:
The system applies preliminary anti-action by using clutch hold pressure to counteract the tendency toward roll-back before the clutch is fully engaged and power transmission begins. The hold pressure creates a counterbalancing force that prevents roll-back during the transition period, allowing the clutch to be released more quickly without compromising vehicle stability.
Data Source
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Figure 3A
AI summary
A device, system, and method for controlling transmission torque to provide hill ascent and/or descent assistance to a vehicle includes applying a clutch hold pressure to one or more clutches of a transmission to lock an output shaft of the transmission to resist roll-back of the vehicle. The clutch hold pressure is determined as a function of the tractive effort of the vehicle and is applied based on one or more of a transmission output speed signal, an engine throttle signal, and a vehicle brake signal.