Vehicle Brake Control Device Using Pedal Speed and Vacuum Pressure
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Solution Overview
Problem
Existing vehicle brake control devices struggle to initiate brake assistance processing at the appropriate timing, especially when a sensor to detect pressure in the variable pressure chamber of the vacuum booster is not provided, leading to inefficient brake assistance during high-speed brake operations.
Innovation Solution
A vehicle brake control device that includes a vacuum booster, a master cylinder, and a brake adjusting mechanism, which determines the start of brake assistance processing based on the operating speed of the brake pedal and the negative pressure in the negative pressure chamber, adjusting the target hydraulic pressure and increase amount to optimize brake assistance without relying on a pressure sensor for the variable pressure chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the brake assistance processing is started based on the assistance limit pressure detected by a pressure sensor, then the brake assistance can be optimized, but the device complexity increases due to the additional sensor
Solution Approach 1:
The system uses existing sensors (brake pedal operating speed sensor and negative pressure chamber pressure sensor) to determine when to start brake assistance processing, eliminating the need for a separate variable pressure chamber pressure sensor. The control unit self-determines the assistance start timing based on readily available data from other system components.
Solution Approach 2:
The existing pressure sensor in the negative pressure chamber serves multiple functions: it monitors negative pressure for normal brake operation and also provides data for determining brake assistance processing start timing, replacing what would otherwise require a dedicated pressure sensor for the variable pressure chamber.
2Reliability
If the brake assistance processing is delayed until the vacuum booster reaches assistance limit, then the system responds accurately to actual needs, but the response time is too late for emergency braking scenarios
Solution Approach 1:
The system performs preliminary action by starting the brake assistance processing before the vacuum booster actually reaches its assistance limit. By using brake pedal operating speed and negative pressure chamber pressure as predictive indicators, the system anticipates when assistance will be needed and initiates it in advance, ensuring timely response during emergency braking.
Solution Approach 2:
The control unit continuously monitors brake pedal operating speed and negative pressure chamber pressure, using this feedback to dynamically determine the optimal timing for starting brake assistance processing. This closed-loop feedback mechanism allows the system to adapt to different braking scenarios and initiate assistance at the most appropriate moment.
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 device effectively initiates brake assistance processing before the vacuum booster reaches its assistance limit, ensuring appropriate brake force assistance during emergency braking, even without a pressure sensor for the variable pressure chamber, thereby improving brake operation efficiency and reducing the gap between intended and actual vehicle deceleration.
Implementation Method 1
the vacuum booster utilizes the differential pressure to assist brake operation force being operation force of a brake pedal by the driver
Implementation Method 2
pressure in the variable pressure chamber is increased by atmospheric air flowing into the variable pressure chamber
Data Source
AI summary
Provided is a vehicle brake control device which is capable of suitably executing brake assistance processing, even if a sensor for detecting the pressure inside a variable-pressure chamber of a vacuum booster is not provided. A brake device is provided with: a vacuum booster for assisting an operation force inputted to a brake pedal; a master cylinder which generates MC pressure Pmc corresponding to the assisted operation force; wheel cylinders which are provided to wheels, and in which WC pressure is increased as the MC pressure Pmc is increased; and a brake actuator capable of adjusting the WC pressure. When it is determined that emergency braking is requested, a control device of the brake device sets, as the assistance limit pressure, the MC pressure Pmc at that point in time, and operates the brake actuator, to execute brake assistance processing for assisting WC pressure increase.