Transfer Case Mode Switching for Hill Stop Anti-Sliding
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Solution Overview
Problem
Four-wheel drive vehicles are at risk of sliding down hills when parked on a slope due to braking rear wheels using an electrical park brake (EPB) or hand brake in high-speed two-wheel drive mode.
Innovation Solution
A method and system that automatically switches the vehicle's drive mode from high-speed two-wheel drive to high-speed or low-speed four-wheel drive modes with stronger brake force without changing the brake system, based on real-time parameter detection, including engine state, transmission gear, slope, and speed, to increase friction forces between tires and ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an electrical park brake (EPB) or hand brake is used to brake rear wheels only, then the brake system structure is simple, but the vehicle is at risk of sliding down a hill when parked on a slope
Solution Approach 1:
The system changes the drive mode parameter from high-speed two-wheel drive to high-speed or low-speed four-wheel drive mode. This parameter change enables the transfer case to engage all four wheels, effectively increasing the braking capability and friction forces without modifying the physical brake system structure, thus resolving the contradiction between simple brake structure and anti-sliding reliability
Solution Approach 2:
The transfer case is made multi-functional by enabling it to provide both drive function and braking function. When switched to four-wheel drive mode, the transfer case engages all four wheels, allowing the drivetrain to serve as a braking mechanism in addition to its primary drive function, thereby improving anti-sliding reliability without adding dedicated braking components
2Force
If the drive mode is switched from high-speed two-wheel drive to high-speed or low-speed four-wheel drive mode, then the friction forces between tires and ground are increased, but the drive mode switching complexity increases
Solution Approach 1:
The system employs feedback mechanisms by using sensors to detect slope angle, vehicle speed, and drive mode status. Based on this feedback information, the control unit automatically determines whether switching to four-wheel drive mode is necessary, thereby managing the complexity of drive mode switching through intelligent control rather than manual operation
Solution Approach 2:
The hill stop control system operates autonomously by automatically detecting parking conditions on slopes and self-activating the four-wheel drive mode without requiring driver intervention. The system monitors relevant parameters and automatically executes mode switching when anti-sliding protection is needed, reducing the operational complexity for the user
3Reliability
If automatic drive mode switching is implemented, then the anti-sliding protection is improved, but the control system complexity increases
Solution Approach 1:
A control unit serves as an intermediary between the sensors (detecting slope, speed, and drive mode) and the transfer case (executing mode switching). This intermediary component coordinates the automatic drive mode switching process, managing the control system complexity by centralizing the decision-making logic and automating the protection mechanism without requiring complex manual control systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively reduces the risk of sliding down hills by increasing friction forces, ensuring safety without altering the brake system.
Implementation Method 1
a transfer case is an important component of a power system of a four-wheel drive vehicle, and its main function is to distribute power outputted by the power system to front and rear drive shafts
Implementation Method 2
braking rear wheels only by using an electrical park brake (EPB) or a hand brake
Implementation Method 3
friction forces between tires and the ground are increased, thereby effectively reducing the risk of sliding down a hill
Data Source
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AI summary
A hill stop control method, apparatus and system for a four-wheel drive vehicle, and a vehicle, which belong to the technical field of automobiles. The method includes: when it is determined that a vehicle is in a park brake state, determining, by acquiring the current parameter of the vehicle, whether the vehicle is in a working condition of being prone to sliding; and when it is determined that the vehicle is in a working condition of being prone to sliding, controlling a mode switch of a transfer case to switch the current drive mode to a high-speed four-wheel drive mode having a stronger brake force or a low-speed drive mode. In this way, the automatic switching of a drive mode is realized without changing a brake system; and when stopped on a hill, friction forces between tires and the ground are increased, thereby effectively reducing the risk of sliding down a hill, and effectively solving the problem of a vehicle being at risk of sliding down a hill due to braking rear wheels only by using an EPB or a hand brake when a four-wheel drive vehicle is in a high-speed two-wheel drive mode and is parked on a road surface having a certain slope.