Transmission Neutral Control Using Adaptive One-Clutch Engagement
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Solution Overview
Problem
Existing vehicle transmission systems face challenges in maintaining a stationary state when the neutral range is selected, leading to inadvertent movement on flat ground due to the default two-clutch neutral state, which can result in creeping or shifting issues.
Innovation Solution
A method and system that utilize a processor to determine a pressure threshold for the transmission lubricant based on temperature and input shaft speed, adjusting the clutch engagement state to either a one-clutch or two-clutch neutral state, and incorporating sensors for diagnostics and brake pedal position to ensure accurate control, thereby preventing unintended vehicle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a two-clutch neutral state is used in the transmission system, then the transmission can maintain a default neutral position, but the vehicle experiences inadvertent movement or creeping on flat ground
Solution Approach 1:
The system dynamically switches between two-clutch neutral state and one-clutch neutral state based on vehicle operating conditions (speed, brake pedal position, gear range). The controller monitors these conditions and adjusts clutch engagement accordingly, making the neutral state adaptive rather than static to prevent inadvertent movement while maintaining ease of operation.
Solution Approach 2:
The system changes the clutch engagement parameter (number of engaged clutches) based on lubricant pressure, temperature, and input shaft speed. By adjusting this parameter dynamically, the system achieves both reliable vehicle stationarity and ease of neutral positioning without contradiction.
2Reliability
If the clutch engagement state is dynamically adjusted based on lubricant pressure and temperature, then vehicle stationarity is improved, but the control system complexity increases
Solution Approach 1:
The existing lubricant pressure sensor and temperature sensor, originally designed for other transmission monitoring functions, are repurposed to also determine clutch engagement state. This multi-functional use of existing sensors increases reliability without adding dedicated hardware complexity.
Solution Approach 2:
The system uses its own existing diagnostic capabilities (lubricant pressure sensor self-diagnostics, temperature sensor self-diagnostics) to determine whether to engage one or two clutches. The transmission control system serves its own stationarity control needs using its own monitoring resources, avoiding additional dedicated components.
3Reliability
If one-clutch neutral state is commanded to prevent vehicle movement, then vehicle stationarity is improved, but the transition smoothness and shift quality may be affected
Solution Approach 1:
The system dynamically selects between one-clutch and two-clutch neutral states based on real-time conditions. During transitions to neutral, the system can use the two-clutch state for smoother engagement, then switch to one-clutch state for stationarity, optimizing both shift quality and vehicle control.
Solution Approach 2:
The system monitors lubricant pressure and temperature in advance to determine the appropriate clutch engagement state before actual neutral selection occurs. This preliminary assessment allows for smoother transitions and better shift quality by preparing the appropriate clutch state ahead of time.
Data Source
AI summary
Systems and methods are provided for controlling a transmission associated with a vehicle. The method includes receiving a neutral range selection for the transmission, and receiving a temperature and a pressure of a lubricant associated with the transmission. The method includes receiving a speed of an input shaft associated with the transmission, and determining, by a processor, based on the temperature and the speed of the input shaft, a pressure threshold value for the lubricant. The method includes outputting, by the processor, one or more control signals to command the transmission to a one clutch neutral state in which one clutch of a plurality of clutches associated with the transmission is engaged based on a comparison of the pressure threshold value to the pressure of the lubricant.