Vehicle Braking Force Allocation for Consistent Deceleration Feel
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Solution Overview
Problem
Existing vehicle braking systems lack a suitable control method for supplementing braking force when the operation amount of the accelerator pedal is small, leading to discomfort for users accustomed to driving vehicles with improved aerodynamic characteristics.
Innovation Solution
A braking force control device that includes a target acceleration calculation unit, a powertrain capability acquisition unit, and an instruction unit, which calculates and instructs the powertrain and brake controllers to generate appropriate braking forces based on the accelerator pedal operation, ensuring a consistent braking experience by distributing the braking force between the powertrain and brake systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If aerodynamic characteristics are improved and engine friction is lowered, then fuel efficiency is improved, but vehicle deceleration becomes smaller leading to user discomfort
Solution Approach 1:
The patent combines the powertrain braking force and brake system braking force into a unified control strategy. The controller integrates both braking sources to achieve the target deceleration, merging the energy recovery function of the powertrain with the mechanical braking capability to maintain familiar deceleration characteristics while preserving fuel efficiency improvements.
Solution Approach 2:
The patent dynamically adjusts the braking force distribution between the powertrain and brake system based on real-time operating conditions. By changing the parameter of braking force allocation rather than relying on a single braking mechanism, the system maintains both improved fuel efficiency and adequate deceleration performance.
2Speed
If braking force is supplemented when accelerator pedal operation is small, then deceleration performance is improved, but control complexity increases
Solution Approach 1:
The controller is designed to perform multiple functions: it manages both the powertrain braking force and the brake system, handles both acceleration and deceleration control, and adapts to different driving conditions. This multi-functionality consolidates control logic into a single device, managing complexity rather than increasing it through additional dedicated components.
Solution Approach 2:
The system automatically determines the appropriate braking force supplementation based on accelerator pedal operation detection. The controller self-regulates the braking force distribution without requiring additional manual input or complex external control systems, making the supplementation process autonomous and integrated into the existing control architecture.
3Manufacturing precision
If braking force is distributed between powertrain and brake, then braking control precision is improved, but system coordination complexity increases
Solution Approach 1:
The patent segments the total braking force requirement into two distinct components: powertrain braking force and brake system braking force. The controller calculates and assigns specific force values to each component based on their respective capabilities and operating conditions, enabling precise control through divided responsibility rather than monolithic control.
Solution Approach 2:
The controller acts as an intermediary that coordinates between the powertrain and brake system. It receives the target deceleration requirement, distributes the braking force allocation between the two systems, and monitors their performance to ensure coordinated operation. This intermediary function simplifies the coordination complexity by providing a centralized decision-making point rather than requiring direct peer-to-peer coordination between subsystems.
Data Source
AI summary
A control device, system and method that distribute a braking request to at least one of a powertrain and a brake based on a braking request by driver operation and a braking force that is generable by the power train. When the braking request is larger than the braking force that is generable by the powertrain, the device, system and method instruct a controller of the powertrain to generate the braking force that is generable by the powertrain, and to instruct a controller of the brake to generate a braking force corresponding to a difference between the braking request and the braking force that is generable by the powertrain.