Brake Control System Slope Gradient Release Rate
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Solution Overview
Problem
Existing brake control systems for vehicles, especially in off-road conditions, experience aggressive and intrusive deceleration on steep slopes, leading to loss of stability and driver discomfort due to high traction demands, particularly in wet or muddy conditions, where anti-lock braking functions override hill descent control.
Innovation Solution
The brake control system incorporates a gradient sensing mechanism, such as an inclinometer, to vary the braking effort retention and release rate based on slope steepness, allowing for a controlled acceleration to a preset speed, and immediately releases braking when the accelerator pedal is signaled, ensuring smooth transitions and maintaining vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the control unit applies large braking effort to prevent vehicle speed from exceeding target value on steep slopes, then vehicle speed control is improved, but wheel lock occurs causing loss of stability and driver confidence
Solution Approach 1:
The system changes the release rate parameter of braking effort based on detected slope gradient. On steeper slopes, the release rate is reduced to prevent wheel lock and maintain stability, while on gentler slopes, the release rate can be higher for faster response. This dynamic parameter adjustment resolves the contradiction between speed control and stability.
2Loss of time
If the brake pedal is released immediately after stopping on a downhill slope, then driver response time is reduced, but the vehicle accelerates too quickly causing aggressive deceleration when brakes are applied
Solution Approach 1:
The control unit performs preliminary action by automatically applying braking effort as soon as the brake pedal is released after stopping on a downhill slope. This preliminary braking prevents the vehicle from accelerating too quickly under gravity, ensuring smooth deceleration when the driver subsequently applies the brakes, while still allowing rapid driver response.
3Speed
If the braking effort is released quickly when the vehicle is held stationary on a slope, then vehicle responsiveness is improved, but traction demands become excessive causing anti-lock braking to override hill descent control
Solution Approach 1:
The system adjusts the braking effort release rate parameter based on the detected slope gradient. On steeper slopes, the release rate is reduced to moderate traction demands and prevent anti-lock braking override, while on gentler slopes, the release rate can be higher for improved responsiveness. This resolves the contradiction between responsiveness and reliability.
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
This approach provides a more controlled and comfortable vehicle descent by adjusting braking effort according to slope steepness, preventing aggressive deceleration and maintaining vehicle stability, enhancing driver confidence and safety.
Implementation Method 1
the gradient sensing means (22) provides a signal indicative of the steepness of the slope
Data Source
Figure 1
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Figure 3
AI summary
A motor vehicle (10) has an inclinometer (22) to determine the steepness of the slope upon which the vehicle stands, brakes (11) and a driver brake pedal (24) for generating a braking effort in the brakes (11). The brakes (11) are also controlled by a brake hydraulic control unit (14) and an electronic control unit (15). The brake hydraulic control unit (14) is arranged to control the release of the braking effort generated to stop the vehicle on a slope by the brake pedal (24) at a release rate which varies as a function of the steepness of the slope determined by the inclinometer (22) following operation of the brake pedal to release the brakes. The vehicle thus achieves controlled descent of a hill after a stationary position. Such a brake control system is particularly advantageous to a motor vehicle having a hill descent mode.