Electric Parking Brake Control Redundancy Without Transmission Lock

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Solution Overview

Problem

The existing electric parking brake (EPB) systems in vehicles face challenges in reducing system costs while maintaining security, particularly in the braking system, where redundant designs and mechanical transmission locks are costly and complex.

Innovation Solution

A motor vehicle system with three control units, each with a microprocessor, where the first two control units independently manage their respective electric parking brake actuators, and the third control unit communicates with the first to activate the first actuator in transmission lock mode, eliminating the need for mechanical transmission locks and enhancing redundancy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical transmission lock is used to secure the vehicle during parking, then the transmission is mechanically secured, but the system complexity and cost increase

Engineering Contradiction:
Improvetransmission securityVSAvoidmechanical transmission lock
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical transmission lock system with an electric parking brake system controlled by electronic control units. The EPB actuators apply braking force to the wheels instead of mechanically locking the transmission, eliminating complex mechanical components while maintaining security function through electrical actuation and electronic control

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the mechanical transmission lock from the vehicle system entirely. By implementing independent electric parking brake control units that directly actuate brake mechanisms, the system eliminates the need for a separate mechanical transmission locking mechanism, simplifying the overall system architecture

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If redundant control units are implemented for each parking brake actuator, then system reliability and security are improved, but the system cost increases

Engineering Contradiction:
Improvecontrol system redundancyVSAvoidmultiple control units
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the parking brake control system into independent control units, with each control unit dedicated to controlling a specific parking brake actuator. This segmentation provides functional redundancy and independence, where each control unit can operate autonomously to ensure reliable brake actuation while maintaining manageable system complexity through modular design

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3529117B2System comprising separate control units for the actuation units of an electric parking brake
Publication Date: 2024.04.17 ZF ACTIVE SAFETY GMBH
  • EP3529117B2 patent drawingFigure 1
  • EP3529117B2 patent drawingFigure 2
  • EP3529117B2 patent drawingFigure 3

AI summary

Described is a motor vehicle system comprising a first electric parking brake actuation unit assigned to a first vehicle wheel, and a second electric parking brake actuation unit assigned to a second vehicle wheel. The system further comprises a first control unit which includes at least one first microprocessor and which is designed to control the first electric parking brake actuation unit and does not allow the second electric parking brake actuation unit to be controlled. Furthermore, a second control unit is provided which comprises at least one second microprocessor and which is designed to control the second electric parking brake actuation unit and does not allow the first electric parking brake actuation unit to be controlled. The redundancy of the two control units increases the system safety. At the same time, the system complexity remains low since no individual control unit has to be designed to control all of the electric parking brake actuation units.