Brake Pump Control for Engine Stop Collision Avoidance
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Solution Overview
Problem
Collision avoidance systems for vehicles with engine automatic stop functions, such as hybrid vehicles, face challenges in ensuring adequate brake assist performance during engine stops due to insufficient negative-pressure brake booster pressure, which compromises safety and fuel efficiency.
Innovation Solution
A vehicle driving support device that includes a front environment recognizing unit, a collision determining unit, and a brake control unit, which automatically starts a brake pump when a high collision probability is detected and the engine is stopped or the brake booster pressure is insufficient, implementing a prefill function to ensure sufficient brake pressure for collision avoidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine automatic stop function is activated to enhance fuel efficiency, then fuel consumption is reduced, but the brake booster cannot generate sufficient negative pressure during engine stop, deteriorating brake assist performance
Solution Approach 1:
The brake control unit starts the pump motor in advance before the driver's braking operation is detected, when collision probability is high and engine stop is predicted. This preliminary action ensures that sufficient brake fluid pressure is available when the driver actually applies the brakes, resolving the contradiction between fuel efficiency (engine stop) and brake assist performance.
Solution Approach 2:
The system dynamically adjusts pump motor operation based on real-time conditions including engine stop state, brake fluid pressure levels, and detected braking operations. The pump motor is controlled to operate at different speeds or start/stop based on current brake pressure requirements, ensuring adequate brake assist performance while minimizing energy consumption during engine stop periods.
2Reliability
If the pump is started after driver's sudden braking operation is detected, then brake assist function is provided, but the responsiveness is insufficient due to pump motor characteristics, failing to achieve desired pressure-rising performance
Solution Approach 1:
The pump motor is started in advance based on prediction of potential braking needs (when collision probability is high and engine stop is detected), rather than waiting for actual braking detection. This preliminary activation allows the brake fluid pressure to build up before the driver applies brakes, achieving the desired pressure-rising performance and responsiveness.
3Use of energy by moving object
If the negative pressure of the brake booster is insufficient during engine stop, then fuel efficiency is maintained, but the brake assist function cannot operate satisfactorily, compromising collision avoidance capability
Solution Approach 1:
The pump motor acts as an intermediary mechanism that supplements the brake booster's insufficient negative pressure generation during engine stop. By actively pumping brake fluid to build pressure in the hydraulic system, the pump motor compensates for the lack of engine-driven vacuum, enabling the brake assist function to operate effectively even when the engine is stopped for fuel efficiency.
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 solution effectively enhances safety by ensuring satisfactory brake assist performance during engine stops, preventing collisions while maintaining fuel efficiency and addressing environmental concerns by ensuring the brake assist function operates with sufficient pressure and responsiveness.
Implementation Method 1
a brake driver pump, to generate brake fluid pressure
Implementation Method 2
a negative pressure of a brake booster is insufficient
Data Source
AI summary
There is provided a vehicle driving support device. The vehicle driving support device according to the present invention calculates a time-to-collision to an obstacle ahead. When the time-to-collision is shorter than a predetermined threshold value, which means the possibility of the collision between the obstacle and a vehicle is determined to be high, and in at least either one of cases in which an engine automatic stop controller automatically stops an engine and in which a brake negative pressure is higher than a set pressure, so that the negative pressure of a brake booster is insufficient, the device outputs a signal to a brake controller so as to start a pump of a brake driver for realizing a prefill function in which a brake pad of each wheel is pressed against a braking surface of a disc rotor.