Engine Stop Device Crankshaft Positioning Control
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Solution Overview
Problem
Existing engine stop devices struggle to accurately and quickly stop the crankshaft at a target position, often requiring high control resolution which leads to longer processing times and potential displacement due to air pressure, affecting fuel efficiency.
Innovation Solution
An engine stop device with a detection part and a control part that selects from multiple maps based on the difference between the current and target crankshaft positions, using a low-resolution map for quick positioning and a high-resolution correction map for precise adjustment, reducing processing load and avoiding unnecessary motor power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high control resolution is used to stop the crankshaft accurately at the target position, then manufacturing precision is improved, but loss of time increases due to longer processing times
Solution Approach 1:
The control process is divided into two distinct phases: a first control phase using a first map with lower resolution forç²— positioning, and a second control phase using a second map with higher resolution for fine positioning. This segmentation allows the system to achieve both speed and accuracy by handling different stages of the stopping process with appropriately optimized control strategies.
Solution Approach 2:
The control system dynamically switches between different maps based on the current crankshaft position and the remaining distance to the target position. The control resolution is adjusted in real-time, transitioning from lower resolution when the crankshaft is far from the target to higher resolution when approaching the target, optimizing both response time and positioning accuracy throughout the stopping process.
2Manufacturing precision
If high control resolution is used to ensure accurate stop position, then device complexity increases due to higher processing requirements
Solution Approach 1:
The control maps are segmented into different resolution levels. The first map contains control data with lower resolution suitable for the majority of the stopping distance, while the second map contains control data with higher resolution for the final positioning phase. This segmentation reduces the overall processing complexity compared to using high-resolution data throughout the entire stopping process.
Solution Approach 2:
Different control resolutions are applied to different portions of the stopping process. Lower resolution control is used when the crankshaft is far from the target position, and higher resolution control is used only when the crankshaft is close to the target position. This local quality approach ensures high accuracy is achieved only where necessary, reducing overall system complexity.
3Productivity
If the crankshaft is stopped quickly at the target position, then productivity is improved, but reliability decreases due to potential displacement by air pressure
Solution Approach 1:
The control system performs preliminary positioning using the first map to bring the crankshaft close to the target position quickly, then switches to the second map with higher resolution for fine adjustment. This preliminary action allows the system to achieve most of the stopping distance rapidly while ensuring final precision, thereby maintaining both productivity and reliability.
Solution Approach 2:
The control system continuously monitors the crankshaft position and uses feedback to determine when to switch between the first and second maps. This feedback mechanism ensures that the crankshaft is positioned accurately at the target position and remains stable, preventing displacement by air pressure while maintaining quick response time.
Data Source
AI summary
An engine stop device includes: a detection part that detects a difference between a current position of a crankshaft and a target stop position of the crankshaft; and a control part that controls a motor based on the detected difference so that the crankshaft is able to approach the target stop position when an engine is stopped or after the engine is stopped. The control part selects one of a plurality of maps that define a relationship between a moving distance and a rotational speed based on the detected difference, and controls the motor based on the selected map.