Transfer Case Range Change Control via Braking
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Solution Overview
Problem
Existing transfer case systems in vehicles lack efficient mechanisms for dynamic range changes between high and low gear settings while moving, often requiring the vehicle to be stationary, and do not effectively manage vehicle speed and braking during range changes.
Innovation Solution
A vehicle control system that outputs range change signals, brake control signals, and selector control signals to manage gear selection, enabling semi-autonomous or autonomous transfer case range changes, including dynamic shifts while moving, and controlling vehicle speed and braking to maintain stability during range changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dynamic range changes are implemented while the vehicle is moving, then the productivity and ease of operation are improved, but the reliability and safety deteriorate due to potential rollaways and loss of vehicle control
Solution Approach 1:
The system applies braking force before the range change is initiated to prevent vehicle movement during the neutral state. The brake control signal is generated in advance based on the range change signal, ensuring the vehicle is secured before the transfer case enters neutral, thus preventing rollaways while enabling dynamic range changes.
Solution Approach 2:
The system continuously monitors vehicle speed and braking status during the range change process. The brake control signal is dynamically adjusted based on feedback from vehicle speed sensors and transmission state, ensuring continuous control stability throughout the range change sequence from engagement through neutral to re-engagement.
2Adaptability or versatility
If the vehicle transmission engages neutral during range change, then the adaptability for dynamic shifts is improved, but the vehicle speed control deteriorates leading to potential acceleration or rollaway
Solution Approach 1:
The brake control signal is generated in advance based on the range change signal, ensuring braking is applied before the transmission enters neutral. This preliminary braking action prevents the vehicle from accelerating or rolling away when the drive connection is disengaged, maintaining speed stability throughout the neutral state.
Solution Approach 2:
The braking system acts as an intermediary between the range change command and vehicle motion. By introducing controlled friction through the brakes, the system mediates the transition through neutral state, preventing uncontrolled speed changes while allowing the transfer case to complete its range change sequence.
3Ease of operation
If a synchroniser is fitted to enable shift-on-the-fly control, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The system replaces complex mechanical synchronising mechanisms with an electronically controlled braking system. Instead of using mechanical synchronisers to match speeds during range changes, the invention uses brake control signals to secure the vehicle, simplifying the mechanical structure while maintaining ease of operation for dynamic range changes.
Data Source
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AI summary
Aspects of the present invention relates to a vehicle control system (1) for controlling a vehicle transfer case (3). The transfer case (3) is operable in a high range and a low range. The vehicle control system (1) is configured to output a range change signal to implement a transfer case range change. The vehicle control system (1) also outputs a brake control signal for controlling vehicle braking during the range change. The present invention also relates to a vehicle (5) and a related method of operating a vehicle control system (1) and optionally also a transmission (7).