Brake System Pitching Motion Control via Speed-Dependent Rear Pressure
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Solution Overview
Problem
Vehicle brake systems experience pitching motion during high braking deceleration, which can be uncomfortable and compromise safety, especially in autonomous braking scenarios where drivers are unprepared for the motion.
Innovation Solution
A brake system with electronic control devices that adjust brake pressure on the rear axle based on vehicle speed, increasing pressure at lower speeds to reduce pitching motion and enhance safety and comfort by distributing brake pressure dynamically between the front and rear axles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high braking deceleration is applied to achieve high braking performance, then braking effectiveness is improved, but pitching motion increases causing discomfort and safety issues
Solution Approach 1:
The patent applies different brake pressures to different axles based on local conditions. The rear axle receives increased brake pressure specifically during braking events to counteract pitching motion, while the front axle maintains normal braking pressure. This localized pressure adjustment eliminates the harmful pitching effect without reducing overall braking performance.
Solution Approach 2:
The system detects braking events in advance and preemptively increases rear axle brake pressure before significant pitching motion occurs. By detecting the braking event early and applying counteracting pressure to the rear axle, the system prevents the harmful pitching motion from developing, rather than reacting after the problem occurs.
2Ease of operation
If brake pressure is increased on the rear axle to reduce pitching motion, then ride comfort is improved, but brake system complexity increases
Solution Approach 1:
The patent utilizes the existing electronic stability program (ESP) pressure control devices and hydraulic lines to implement rear axle pressure adjustment. By making the existing ESP system multi-functional—using it both for stability control and for pitching motion compensation—the patent avoids adding dedicated new hardware, thereby limiting the increase in system complexity.
Solution Approach 2:
The brake system uses its own existing components (ESP pressure control devices, hydraulic lines, and controller) to solve the pitching motion problem. The system serves itself by utilizing its built-in capabilities rather than requiring entirely separate dedicated systems, thus improving comfort without proportionally increasing complexity.
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
The system effectively reduces pitching motion, improving ride comfort and safety by adapting brake pressure distribution according to speed, allowing for increased braking deceleration without excessive physical strain on occupants.
Implementation Method 1
a master cylinder is operated with a brake pedal and pressure is generated in a pressure chamber filled with brake fluid. The brake fluid is passed by way of hydraulic lines to wheel brake cylinders
Implementation Method 2
In some instances, a brake booster may be provided to increase the braking force
Data Source
AI summary
A brake system for a motor vehicle having front and rear axles, the brake system having front and rear axle braking mechanisms operated under pressure control devices for producing a respective brake pressure on the front and rear axles of the motor vehicle. A controller receives signal information from sensors and systems on the motor vehicle to detect initiation of a braking process and detect a current speed of travel of the motor vehicle. An initial brake pressure for the rear axle braking mechanism is determined by the controller. A target brake pressure for the rear axle braking mechanism is determined by the controller and is representative of an increase in pressure relative to the initial brake pressure and the current speed of travel. Instructions from the controller operate the pressure control devices to produce the target brake pressure at the rear axle braking mechanism.