Brake Actuating Unit With Redundant Pressure Supply Fallback
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Solution Overview
Problem
Current brake-by-wire motor vehicle systems are not suitable for highly automated driving scenarios as they may not ensure safety in case the driver is not attentive to actuate the brake pedal during system failures, necessitating a compact and safe solution.
Innovation Solution
A brake actuating unit with two electrically controllable pressure supplying devices and connectors, allowing for a compact one-box design with redundant power supply, enabling fallback braking in case of partial system failure, and incorporating a brake pedal feel simulator and hydraulic controller for enhanced safety and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional brake-by-wire system with a single pressure supplying device is used, then the device complexity is reduced, but the reliability decreases because the driver may not be able to actuate the brake pedal in case of system failure during highly automated driving
Solution Approach 1:
The brake actuating unit is divided into two independent pressure supplying devices (first and second) with separate hydraulic circuits. Each device can independently generate braking pressure, allowing the system to maintain braking capability even if one device fails. This segmentation creates functional redundancy that directly addresses the reliability concern in highly automated driving scenarios.
Solution Approach 2:
The system incorporates a fallback mode where the second pressure supplying device is prepared in advance to take over braking functions if the first device fails. The brake pedal actuation sensing device continuously monitors the system state, and the control unit is configured to automatically switch to the second device when a failure is detected, providing beforehand cushioning against system failure.
2Reliability
If two separate pressure supplying devices with separate connectors are used, then the reliability improves through redundancy, but the volume and device complexity increase
Solution Approach 1:
The first and second pressure supplying devices are integrated into a single common housing, sharing the same structural enclosure. The hydraulic controller and other control components are also merged into this unified structure. This merging approach allows the system to achieve the volume reduction of a compact single-device design while maintaining the reliability benefits of dual independent pressure supplying devices.
3Reliability
If two separate connectors for power supply are used, then the reliability improves through redundant power supply, but the device complexity and number of components increase
Solution Approach 1:
The first and second connectors are designed with identical pin assignments and electrical configurations, making them universally interchangeable. Both connectors can serve the same functional purpose of providing power and control signals to the pressure supplying devices. This universal design simplifies the overall system architecture and reduces complexity while maintaining redundant power supply capability.
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 solution provides a safe and compact brake system capable of ensuring vehicle braking even in case of partial system failure, enhancing safety in highly automated driving scenarios by enabling redundant power supply and fallback braking modes.
Implementation Method 1
a first electrically controllable pressure supplying device (7), a second electrically controllable pressure supplying device (8)
Implementation Method 2
a first cylinder and piston arrangement, in particular a master cylinder and piston arrangement, disposed within the housing (16)
Data Source
AI summary
The present application relates to a brake actuating unit for a brake-by-wire motor vehicle brake system. The brake actuating unit comprises a housing, a first electrically controllable pressure supplying device, and a second electrically controllable pressure supplying device. The brake actuating unit further comprises a first connector for electrically connecting the brake actuating unit with a vehicle control unit and with a power network. The first connector is electrically connected with the first electrically controllable pressure supplying device. The brake actuating unit comprises a second connector for electrically connecting the brake actuating unit with the vehicle control unit and with the power network. The second connector is electrically connected with the second electrically controllable pressure supplying device. The brake actuating unit comprises a first cylinder and piston arrangement disposed within the housing and a piston rod for transmitting a displacement of a brake pedal to a piston.