Electromechanical Wheel Brake Fallback Control via Redundant Links
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Solution Overview
Problem
Electromechanical braking systems lack a mechanical connection between the brake pedal and wheel brakes, preventing direct muscle power application and regulation of braking torque in fallback modes, especially in case of central electrical control failures.
Innovation Solution
A braking system with a central brake control unit connected to local brake control units via redundant data connections, allowing direct actuation information transmission and independent actuation, ensuring continued braking functionality even in central control unit failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If electromechanical brakes mechanically decouple the brake pedal from the wheel brakes, then braking force amplification and distribution can be electrically controlled, but direct muscle power application and fallback mode operation are lost
Solution Approach 1:
The braking system is segmented into multiple independent control paths: a primary electrical control path through the central brake control unit, and a secondary direct mechanical actuation path through the brake actuation unit. This segmentation allows the system to maintain fallback capability by dividing the control architecture into independent segments that can operate autonomously if one fails.
Solution Approach 2:
The system changes the actuation parameter transmission mode between normal and fallback modes. In normal mode, braking parameters are transmitted electrically via data connections. In fallback mode, the system switches to direct mechanical parameter transmission through the brake actuation unit, changing the physical state of parameter transmission from electrical to mechanical.
2Reliability
If redundant data connections are added for fallback mode operation, then braking reliability is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The brake actuation unit serves multiple functions: it acts as a data transmission interface during normal operation and as a direct mechanical actuator during fallback mode. This multi-functionality reduces the need for completely separate redundant systems, thereby reducing overall device complexity while maintaining reliability.
Solution Approach 2:
The brake actuation unit functions as an intermediary element that can operate in two modes: transmitting electrical data signals during normal operation and transmitting mechanical actuation forces during fallback mode. This intermediary component provides a bridge between electrical and mechanical domains, enabling redundancy without requiring fully duplicate systems.
Data Source
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AI summary
The invention relates to a brake system (100) for a motor vehicle with electromechanical wheel brakes (104, 106, 108, 110), with a brake actuation unit (112) and with a central brake control unit (102), wherein the wheel brakes (104, 106, 108, 110) each have a local brake control unit (118, 120, 122, 124), the central brake control unit (102) is directly connected to the brake actuation unit (112) and the local brake control units (118, 120, 122, 124) of the wheel brakes (104, 106, 108, 110) via a first data connection (154), whereas the brake actuation unit (112) is directly connected to the local brake control unit (118, 120, 122, 124) of at least one wheel brake (104, 106, 108, 110) via a second data connection (156). The central brake control unit (102) is, in a normal operating mode of the brake system (100), designed to ascertain at least one braking demand from a first actuation information item, received in particular via the first data connection (154), of the brake actuation unit (112) and to transmit control signals corresponding to the braking demand to the local brake control units (118, 120, 122, 124) of the wheel brakes (104, 106, 108, 110). The local brake control units (118, 120, 122, 124) of the wheel brakes (104, 106, 108, 110) are, in a fall-back level operating mode of the brake system (100), designed to actuate the respective wheel brakes (104, 106, 108, 110) on the basis of a second actuation information item, received via the second data connection (156), of the brake actuation unit (112).