Isolation Valve Brake Layout for Fallback ABS and Rear Proportioning
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Solution Overview
Problem
Existing electro-hydraulic brake systems fail to maintain dynamic rear proportioning and stability in the event of a manifold block failure, which is critical for higher levels of vehicle autonomy, and they also consume excessive energy and lack efficient self-pressure testing capabilities.
Innovation Solution
The electro-hydraulic brake system incorporates a master cylinder block with a protrusion and isolation valves, which allow for fallback ABS functions and reduced energy consumption, enabling dynamic rear proportioning and self-pressure testing, even in the absence of a functioning manifold block, by regulating brake fluid flow and pressure through a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a manifold block is used for individual wheel pressure control, then ABS, traction control, and stability control functions are achieved, but the system becomes complex and vulnerable to failure that compromises vehicle stability
Solution Approach 1:
The brake system is divided into two independent circuits: a primary circuit through the manifold block for normal operation, and a secondary circuit through the isolation valves for fallback operation. This segmentation ensures that failure in one circuit does not compromise the entire system's ability to maintain vehicle stability.
Solution Approach 2:
The system changes the operational parameters of the isolation valves from a dormant state to an active state upon detecting manifold block failure. The isolation valves transition from being closed/off to open/active, altering the fluid flow path from the primary to the secondary circuit, thereby maintaining brake control functions despite the failure.
2Device complexity
If the master cylinder block provides equal pressure to all wheels, then the system is simple, but rear wheels may lock-up during deceleration causing vehicle instability
Solution Approach 1:
The pressure distribution is segmented into front and rear axle control through the isolation valves. The first isolation valve controls pressure to front wheels while the second isolation valve controls pressure to rear wheels, enabling independent pressure regulation to prevent rear wheel lock-up during deceleration.
Solution Approach 2:
The isolation valves act as intermediary components between the master cylinder block and the wheel brakes. They mediate the pressure distribution by selectively directing brake fluid to specific wheel circuits, allowing dynamic rear proportioning to maintain vehicle stability during deceleration.
3Reliability
If isolation valves are added to the master cylinder block, then fallback ABS function and dynamic rear proportioning are enabled, but the device complexity increases
Solution Approach 1:
The isolation valves are merged with the master cylinder block structure, with the valves and their actuators integrated directly into the master cylinder housing. This combining approach enables fallback ABS and dynamic rear proportioning functions while minimizing the increase in overall device complexity by sharing structural and control resources.
4Duration of action of stationary object
If a brake-by-wire system is used for regenerative brake blending, then battery life is extended, but the brake pedal feel must be simulated and the system becomes more complex
Solution Approach 1:
The isolation valves serve as intermediary components that enable the brake-by-wire system to maintain vehicle stability during deceleration by providing independent rear axle pressure control. This intermediary function is essential for achieving regenerative brake blending while maintaining safety requirements for autonomous vehicles.
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 solution ensures vehicle stability and energy efficiency by maintaining dynamic rear proportioning and enabling self-pressure testing, thus meeting the requirements for higher levels of vehicle autonomy and reducing energy consumption.
Implementation Method 1
at least one isolation valve disposed on the rear surface, spaced apart from the protrusion and received by the master cylinder electronic control unit, for regulating brake fluid flow from the master cylinder block to the wheel brakes
Data Source
AI summary
An electro-hydraulic brake system comprises a master cylinder block in fluid communication with a reservoir tank containing a brake fluid. The master cylinder block defines a bore and primary and secondary openings. A protrusion extends outwardly from a rear surface of the master cylinder block. A pressure supply unit coupled to a front surface of the master cylinder block and in fluid communication with the reservoir tank for supplying the brake fluid from the reservoir tank. A master cylinder electronic control unit couples to the rear surface and in an abutment relationship with the protrusion. At least one isolation valve disposed on the rear surface, spaced apart from the protrusion and received by the master cylinder electronic control unit, for regulating brake fluid flow from the master cylinder block to the wheel brakes.