Vehicle Braking System Actuator Segmentation for Cost and Responsiveness
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Solution Overview
Problem
Existing vehicle braking systems face challenges in reducing manufacturing costs while maintaining responsiveness, particularly with small electric motors used in brake-by-wire systems, where field-weakening control is necessary to enhance responsiveness but may compromise performance during sudden braking or heavy loads.
Innovation Solution
A vehicle braking system comprising an operation amount detector, a hydraulic pressure source with a first actuator using an electric motor to generate brake hydraulic pressure and a second actuator with a pump to pressurize brake fluid, and a controller that selectively operates these actuators based on the detected operation amount, allowing for efficient generation of brake hydraulic pressure and independent control of wheel braking forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a small electric motor is used to reduce manufacturing cost, then manufacturing cost is reduced, but responsiveness during sudden braking deteriorates
Solution Approach 1:
The braking system is divided into two independent actuators: a first actuator with a small electric motor for normal braking, and a second actuator with a large electric motor for emergency braking. This segmentation allows each motor to be optimized for its specific function, reducing overall cost while maintaining high responsiveness when needed.
Solution Approach 2:
The control unit dynamically switches between the first actuator and second actuator based on braking conditions. During normal braking, the small motor operates; during emergency braking detected by the operation amount detector, the system switches to the large motor, providing adaptive responsiveness.
2Speed
If field-weakening control is applied to increase responsiveness, then responsiveness is improved, but performance during heavy loads deteriorates
Solution Approach 1:
The control unit dynamically selects between two actuators based on braking conditions. The first actuator uses field-weakening control for responsive normal braking, while the second actuator provides full power for emergency braking, avoiding the limitations of field-weakening under heavy loads.
Solution Approach 2:
The system changes the operational parameters by switching between two different motor configurations. The first motor operates with field-weakening parameters for responsiveness, while the second motor provides high torque parameters for heavy load braking, optimizing performance across different operating conditions.
3Speed
If a single large electric motor is used to ensure high responsiveness, then responsiveness is improved, but device complexity and cost increase
Solution Approach 1:
Instead of one large motor, the system segments the braking function into two actuators with different motor sizes. The first actuator handles normal braking with a small motor, and the second actuator handles emergency braking with a larger motor, reducing overall system complexity and cost.
Solution Approach 2:
The first actuator with the small motor provides sufficient braking power for partial (normal) braking conditions, while the second actuator is reserved for excessive (emergency) braking situations, avoiding the need for a single oversized motor that would increase complexity and cost.
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 configuration reduces the size and weight of the electric motor, maintains responsiveness during normal braking, and provides high responsiveness during emergency braking by switching between the actuators, thereby reducing manufacturing costs and improving brake feel while preventing vibration and noise.
Implementation Method 1
The electric motor is configured to move the piston forwardly to generate the brake hydraulic pressure
Implementation Method 2
The second actuator includes a pump configured to pressurize brake fluid located downstream of the first actuator
Data Source
AI summary
A vehicle braking system includes an operation amount detector, a hydraulic pressure source, a controller, and a wheel cylinder. The hydraulic pressure source is to generate brake hydraulic pressure corresponding to an amount of operation detected by the operation amount detector. The wheel cylinder is to be operated by the brake hydraulic pressure generated by the hydraulic pressure source. The hydraulic pressure source includes a first actuator and a second actuator. The first actuator includes a piston and an electric motor. The electric motor is configured to move the piston forwardly to generate the brake hydraulic pressure. The second actuator includes a pump configured to pressurize brake fluid located downstream of the first actuator. The controller is configured to selectively operate the first actuator and the second actuator based on the amount of operation detected by the operation amount detector.