Vehicle Control Device Braking Force Timing for Startability
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Solution Overview
Problem
The existing vehicle control systems face challenges in improving startability when the accelerator pedal is depressed between the time the vehicle comes to a stop and when idling stop control is executed, due to delayed deactivation of braking force generated by hill-hold, leading to decreased vehicle startability.
Innovation Solution
A vehicle control device and method that determines whether the vehicle is stopped and the electric oil pump is driven, applying braking force after the vehicle is stopped and the electric oil pump is determined to be driven, ensuring the braking force is not generated prematurely when the accelerator pedal is depressed, thus preventing delayed start of the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If hill-hold is performed by closing a drain circuit for brake fluid pressure, then the generation confirmation time period is short, but the braking force deactivation is delayed when accelerator pedal is depressed
Solution Approach 1:
The controller determines whether the accelerator pedal is depressed before the hill-hold control is deactivated. When the accelerator pedal is depressed, the controller promptly deactivates the hill-hold control without waiting for the predetermined time period to elapse, allowing the braking force to be released immediately and enabling prompt vehicle start
2Reliability
If electric oil pump drive confirmation is required before idling stop control, then hydraulic pressure supply is ensured, but the drive confirmation time period becomes longer than generation confirmation time period
Solution Approach 1:
The controller determines the accelerator pedal state in advance and prepares to deactivate hill-hold control promptly when acceleration is requested. This preliminary determination allows the system to override the normal deactivation timing and immediately release braking force when needed, resolving the timing mismatch between pump confirmation and brake release
3Stability of the object's composition
If braking force is applied before vehicle stop determination, then hill-hold is activated early, but vehicle startability declines when accelerator pedal is depressed during engine continuous operation
Solution Approach 1:
The controller continuously monitors the accelerator pedal state and uses this feedback to determine when to deactivate hill-hold control. When the accelerator pedal is depressed, the controller receives feedback indicating the driver's intention to accelerate and promptly deactivates the braking force, enabling smooth vehicle start
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 enhances vehicle startability by ensuring the braking force decreases as the brake pedal is released, allowing the vehicle to start promptly in response to accelerator pedal depression, improving overall startability.
Implementation Method 1
supply a hydraulic pressure necessary for the vehicle using an electric oil pump
Implementation Method 2
a predetermined braking force is generated even if depression of a brake pedal is cancelled
Data Source
AI summary
A vehicle control device controls a vehicle that has an electric oil pump, executes idling stop control for stopping a drive source when predetermined conditions are satisfied, and is capable of applying a braking force in a state where a brake pedal is released. The vehicle control device determines whether or not the vehicle is stopped, determines whether or not the electric oil pump is driven, and executes the idling stop control when stop of the vehicle is determined, driving of the electric oil pump is determined, and the braking force is applied to the vehicle. Application of the braking force is started after the vehicle is determined to be stopped and the electric oil pump is determined to be driven.