Switch-off Path Testing in Engine Control Units
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Solution Overview
Problem
Existing engine control unit systems cannot perform switch-off path tests during ongoing operation without interfering with engine activation, particularly in continuous operation scenarios like stationary or large-scale diesel applications, which compromises safety and requires tests to be done only during engine start or run-up.
Innovation Solution
A method to conduct switch-off path tests independently of engine start by identifying suitable time windows based on engine clock, phase, and rotational speed, ensuring tests are carried out when components are not activated, and repeating checks in defined intervals to prevent rotational speed drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switch-off path tests are carried out prior to engine start during run-up, then safety checks can be performed, but the tests cause noticeable interruptions in engine activations and cannot be performed during continuous operation
Solution Approach 1:
The patent implements dynamic test scheduling by monitoring engine operational state (running vs. stopped) and adapting test execution timing accordingly. The control unit dynamically selects between different test approaches: during engine running, tests are performed in synchronization with combustion cycles using crankshaft position sensing; during engine stop, tests are performed immediately. This dynamic adaptation resolves the contradiction by enabling safety tests during continuous operation without causing interruptions.
Solution Approach 2:
The patent employs periodic testing synchronized with the engine's combustion cycle. When the engine is running, switch-off path tests are periodically executed at specific crankshaft positions (e.g., when the piston is in a defined position during the compression stroke). This periodic action allows safety checks to be performed regularly during continuous operation without disrupting engine function, as tests are confined to specific phases of the natural engine cycle.
2Reliability
If switch-off path tests are performed during ongoing engine operation, then safety is increased and error detection is improved, but the tests may interfere with torque-relevant activations
Solution Approach 1:
The patent applies local quality by performing tests at specific localized positions within the engine cycle rather than uniformly throughout operation. The control unit determines crankshaft position using a crankshaft position sensor and selects specific angular positions (e.g., when the piston is in a defined position during compression) for test execution. This localized approach ensures tests are conducted in regions of the engine cycle where they least interfere with torque-relevant activations, resolving the contradiction between error detection and operational interference.
Solution Approach 2:
The patent implements preliminary action by checking engine operational state and determining optimal test timing before executing switch-off path tests. The control unit continuously monitors engine running state and crankshaft position, then proactively schedules tests during appropriate windows (either during running engine at safe crankshaft positions or immediately upon engine stop). This preliminary planning prevents interference with torque-relevant activations by ensuring tests are initiated only when engine state permits.
3Ease of operation
If switch-off path tests are carried out only once during engine run-up, then the system is simple to operate, but safety is compromised in continuous operation scenarios
Solution Approach 1:
The patent implements multi-functionality by creating a universal test execution framework that operates effectively across different engine operational modes. The control unit is designed to perform switch-off path tests both during engine run-up (traditional approach) and during continuous operation (new capability). The system universally handles multiple scenarios: engine starting, engine running with periodic testing, and engine stopping with immediate testing. This universal approach maintains operational simplicity while significantly improving safety coverage for continuous operation scenarios.
Data Source
AI summary
A device and a method for checking switch-off paths in control units of internal combustion engines during ongoing engine operation.