Independent Vehicle Securement for Park Pawl CAN Failures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrified vehicle securement strategies, such as engaging a park pawl, are inadequate in ensuring proper shutdown and securement when a controller area network (CAN) malfunction occurs, leading to potential vehicle rollaways and battery drain.
Innovation Solution
An independent electronic securement and ignition management system is introduced, comprising a park pawl system, an electric parking brake (ePB), and a vehicle controller connected via CAN. The system automatically engages the ePB to inhibit vehicle movement in case of a park pawl system malfunction, without operator input, and controls powerdown/key-off to prevent battery drain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional park pawl securement strategy is used in electrified vehicles, then the vehicle can be secured from moving under normal conditions, but the vehicle cannot be verifiably secured or properly shutdown when a CAN malfunction occurs
Solution Approach 1:
The securement function is segmented into two independent systems: the park pawl system and the electric parking brake (ePB) system. Each system can independently secure the vehicle, providing redundancy. The park pawl handles normal securement operations, while the ePB serves as an independent backup that can be activated without relying on CAN communication, thus resolving the contradiction between reliability and complexity by dividing the securement function into separate operational pathways
Solution Approach 2:
The system changes the operational parameter from single-source securement (park pawl only) to dual-source securement (park pawl + ePB). By introducing the ePB as an alternative securement mechanism that operates independently of CAN communication, the system maintains reliability under malfunction conditions without significantly increasing overall system complexity, as the ePB integration leverages existing hardware components
2Ease of operation
If the vehicle controller automatically commands ePB engagement upon detecting park pawl system malfunction, then the vehicle can be secured without operator input, but the system requires enhanced monitoring and control capabilities
Solution Approach 1:
The vehicle controller automatically detects park pawl system malfunctions and commands ePB engagement without requiring operator intervention. The system monitors its own operational status and self-corrects by switching to the backup securement method, thereby improving ease of operation while the added monitoring and control logic represents a manageable increase in system complexity that enables autonomous malfunction response
3Reliability
If the vehicle controller monitors park pawl system status via CAN to detect malfunctions, then automatic ePB engagement can be triggered, but communication failures or CAN bus issues may go undetected
Solution Approach 1:
The system prepares for potential CAN communication failures by having the ePB system ready as a pre-configured backup securement method. The dual-controller architecture (primary and secondary park pawl controllers) ensures that if CAN communication fails, the system can still detect the malfunction state through alternative means and activate the ePB, thus cushioning against the harmful effect of CAN bus vulnerabilities while maintaining reliable malfunction detection
Data Source
AI summary
Independent electronic securement and ignition management techniques for an electrified vehicle includes a park pawl system with primary and a secondary park pawl controllers configured to control park state arbitration and physical movement of a park pawl actuator, respectively, an electric parking brake (ePB), and a vehicle controller connected to the park pawl system via a controller area network (CAN) and configured to detect a malfunction of the park pawl system and, in response to detecting the park pawl system malfunction, automatically command the ePB to engage to inhibit movement of the electrified vehicle and without any input from an operator of the vehicle.