Brake-by-wire Control Unit Segmentation for Redundancy
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Solution Overview
Problem
Vehicle brake systems of the 'brake-by-wire' type face challenges in maintaining the availability of the service brake function, particularly in the event of failures or errors in the electronic control unit or electrical wiring system, leading to non-boosted braking scenarios.
Innovation Solution
The control unit for the motor-and-pump assembly is separated into a logic module and a power module, each connected separately to the vehicle's electrical wiring system, allowing for redundancy and independent operation to prevent failures in one module from affecting the other, with the power module often located outside the control unit to manage heat dissipation and reduce component costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control unit for the motor-and-pump assembly is integrated into the brake system control unit, then the device complexity is reduced and cost is lowered, but the reliability of the service brake function decreases because a single point of failure in the electronic control unit can cause both logic and power failures
Solution Approach 1:
The control unit is segmented into two independent modules: a logic module for control functions and a power module for electrical power delivery. These modules are physically separated and connected through a connector, allowing independent operation and failure isolation. The logic module can remain functional even if the power module fails, and vice versa, thereby maintaining service brake function availability.
2Device complexity
If the power module is integrated into the control unit, then the device complexity is reduced, but the heat dissipation capability deteriorates and requires additional cooling structures
Solution Approach 1:
The power module, which generates significant heat during operation, is extracted from the control unit and positioned separately. This spatial separation allows the power module to be equipped with dedicated heat dissipation structures without increasing the thermal load on the control unit's electronic components. The connector between the logic module and power module provides both electrical connection and mechanical support while maintaining thermal isolation.
3Device complexity
If the logic module and power module are connected to the electrical wiring system through a single connection point, then the device complexity is reduced, but the reliability decreases because a failure at the connection point can disable both modules
Solution Approach 1:
The electrical connection structure is segmented into separate connection paths for the logic module and power module. Each module has its own connection point to the vehicle's electrical wiring system, allowing independent power supply and signal transmission. This segmentation ensures that a failure in the electrical connection affecting one module does not necessarily affect the other module, thereby maintaining system reliability.
Data Source
AI summary
A device for supplying pressure to an actuation unit of a vehicle brake system, in particular to a vehicle brake system of the ‘brake-by-wire’ type, comprising a pneumatic motor-and-pump assembly with a pump and a motor driving the pump, wherein the motor-and-pump assembly is controlled by an electronic control unit depending on a pressure level or pressure difference in a pneumatic brake booster of the actuation unit, with the pressure level in a chamber or a difference in pressure between two chambers of the brake booster being detected by means of a sensor. In order to maintain the availability of the service brake function as high as possible and to obtain a maximum possible redundancy, the control unit, used to control the motor-and-pump assembly comprises a logic module and a power module, which are arranged separately of each other.