ESC Hydraulic Backup Braking for Brake-Actuation Unit Failure
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Solution Overview
Problem
Conventional braking systems with a single hydraulic unit face limitations in providing effective braking support when the brake-actuation hydraulic unit fails, leading to reduced functionality and inability to maintain driver-induced or autonomous braking.
Innovation Solution
The integration of an ESC hydraulic unit with a brake-actuation hydraulic unit, utilizing a control device that activates the ESC hydraulic unit's pump to draw brake fluid from a reservoir and/or controls electric motors to provide additional braking torque, ensuring continued driver-induced and autonomous braking even in the event of failures or impairments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional braking system uses a single brake-actuation hydraulic unit, then the system structure is simple, but the braking performance deteriorates when the hydraulic unit fails
Solution Approach 1:
The braking system is divided into two independent hydraulic units: a brake-actuation hydraulic unit for normal braking operations and an ESC hydraulic unit for emergency and stability control functions. This segmentation ensures that failure of one unit does not compromise the other, maintaining braking performance under failure conditions while keeping each unit's structure relatively simple.
Solution Approach 2:
The system changes the operational state of the ESC hydraulic unit based on detected failure conditions. When a failure is detected in the brake-actuation hydraulic unit, the control device activates the ESC hydraulic unit to take over braking functions, changing the system's operational parameters to maintain reliability.
2Reliability
If the ESC hydraulic unit is activated to compensate for brake-actuation hydraulic unit failure, then braking reliability is improved, but the system complexity increases
Solution Approach 1:
The ESC hydraulic unit is designed with multi-functionality to perform both emergency braking and stability control operations. This allows a single hydraulic unit to handle multiple functions, reducing the need for additional dedicated emergency braking systems and thereby limiting the increase in overall system complexity.
Solution Approach 2:
The control device automatically detects failures in the brake-actuation hydraulic unit and activates the ESC hydraulic unit without requiring manual intervention. The system performs self-diagnosis and self-correction, maintaining reliability while keeping the control logic integrated and manageable rather than requiring complex external control systems.
3Reliability
If the ESC hydraulic unit draws brake fluid from the reservoir to maintain braking pressure, then braking performance is maintained, but the brake fluid consumption increases
Solution Approach 1:
The ESC hydraulic unit's pump operates continuously or in repeated cycles to maintain braking pressure in the wheel brake cylinders when the brake-actuation hydraulic unit fails. This continuous action ensures that braking pressure is sustained throughout the failure period, maintaining braking performance until the vehicle stops or the failure is resolved.
Solution Approach 2:
The system draws brake fluid in targeted amounts to maintain necessary braking pressure rather than continuously filling the system. The control device monitors pressure levels and activates the pump only when pressure drops below threshold levels, using partial action to maintain reliability while minimizing unnecessary brake fluid consumption.
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 enables enhanced braking comfort and safety by maintaining effective braking performance through adaptive fluid volume and torque adjustments, supporting driver-induced and autonomous braking, even in the presence of hydraulic unit failures.
Implementation Method 1
activate the at least one pump of the ESC hydraulic unit in order to draw in the brake fluid volume corresponding to the specified target volume from the brake fluid reservoir
Implementation Method 2
actuate the at least one electric motor in order to effect the motor braking torque corresponding to the specified target braking torque at the at least one wheel
Data Source
AI summary
A control device and method for a braking system. The method includes reading out or checking, based on at least one signal, whether a predefined error state exists at a brake-actuation hydraulic unit, which is mounted on an ESC hydraulic unit, and performing at least one of the following steps if it is determined that the at least one predefined error state exists at the brake-actuation hydraulic unit: activating at least one pump of the ESC hydraulic unit in order to draw in a firmly predefined or specified brake fluid volume from a brake fluid reservoir of the braking system, and/or controlling at least one electric motor of the vehicle which can be operated in a regenerative mode, to effect a firmly predefined or specified motor braking torque not equal to zero at at least one wheel of the vehicle and/or at least one axle of the vehicle.