Brake Control System Regenerative Cooperation
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Solution Overview
Problem
Existing brake control systems face difficulties in accurately performing various brake controls, particularly in hybrid and electric vehicles, due to complex calculations required for regenerative cooperation brake control, leading to inconsistent brake force delivery and poor brake operation feeling.
Innovation Solution
A brake control system that includes an input member, a movable piston, an actuator, and a control unit with relative displacement and fluid pressure controllers, allowing for precise control of brake fluid pressure and relative displacement based on brake pedal operation, enabling effective switching between different control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If regenerative cooperation brake control is implemented by converting brake effect into relative displacement between input member and primary piston, then regenerative braking can be achieved, but the control becomes complicated with cumbersome calculations
Solution Approach 1:
The control unit is divided into two independent controllers: a relative displacement controller that handles mechanical brake control based on input member displacement, and a fluid pressure controller that handles hydraulic pressure control. This segmentation allows each controller to operate independently without complex conversions between different physical quantities, simplifying the overall control system while maintaining regenerative braking capability.
Solution Approach 2:
The control unit is designed with dual control capabilities that can function independently or in combination. The relative displacement controller and fluid pressure controller both receive brake pedal operation signals and can independently generate appropriate control signals for the actuator, providing universal applicability across different braking scenarios including regenerative braking, conventional braking, and emergency braking.
2Ease of operation
If control is based on relative displacement between input member and primary piston, then mechanical brake operation can be controlled, but brake force delivery becomes inconsistent and brake operation feeling deteriorates
Solution Approach 1:
The fluid pressure controller incorporates feedback from a fluid pressure detector that continuously monitors the actual brake fluid pressure. This feedback is compared with the target pressure, and the control signal to the actuator is adjusted based on the pressure difference, ensuring consistent brake force delivery and improving brake operation feeling through active pressure regulation.
Solution Approach 2:
The system transitions from controlling only mechanical displacement to controlling both displacement and fluid pressure as independent parameters. By introducing fluid pressure as a controllable parameter with direct feedback, the system achieves more precise and consistent brake force delivery while maintaining responsive brake operation feeling.
3Adaptability or versatility
If complex conversion calculations are performed to accommodate regenerative braking, then various brake controls can be achieved, but responsiveness and brake operation feeling become poor
Solution Approach 1:
The control system is segmented into independent control pathways that process brake pedal signals directly without requiring complex conversion calculations. The relative displacement controller and fluid pressure controller each have straightforward control logic that responds immediately to driver input, eliminating computational delays while maintaining versatility through the ability to switch between control modes.
Solution Approach 2:
The control unit pre-processes brake pedal signals to generate target values for both relative displacement and fluid pressure simultaneously. This preliminary action allows the system to prepare control commands in advance without waiting for complex real-time conversions, improving response speed while maintaining the capability to perform various brake controls.
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 enables accurate and efficient execution of various brake controls, improving brake operation feeling and responsiveness by directly controlling brake fluid pressure and relative displacement, thus addressing the challenges of regenerative cooperation brake control and other control complexities.
Implementation Method 1
a master cylinder 2, configured to generate a brake fluid pressure by a relative movement between the input member 17 and the piston 8
Data Source
AI summary
A brake control system displaces a primary piston by controlling an operation of the electric motor by a master pressure control unit according to the operation amount (Xop) of the brake pedal, thereby generating a hydraulic pressure in the master cylinder to supply it to wheel cylinders (Ba to Bd). The master pressure control unit sets a target relative displacement (ΔXT) between an input piston and the primary piston and a target hydraulic pressure (PT) in the master cylinder, and appropriately switch which is used to control a brake force. During regenerative cooperation, the master pressure control unit selects the control with use of the target hydraulic pressure, which enables easy execution of a hydraulic pressure control including a subtraction of the hydraulic pressure corresponding to a brake effect from the regenerative cooperation.