Engine Intake Control Switching Valve Characteristics for Power Stability
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Solution Overview
Problem
Existing intake-air quantity control systems for engines face fluctuations in power output due to disturbances like intake-air flow pulsations and temperature variations, particularly in high-load ranges, leading to reduced performance.
Innovation Solution
An intake-air quantity control system that employs a variable valve operating device to switch between different target operating characteristics of the intake valve, using a high-load period valve operating characteristic preset for full-load operations and a basic target operating characteristic calculated for other engine operating ranges, to stabilize engine power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the intake-valve operating characteristic is calculated based on target intake-air quantity using disturbance-affected processing, then the control system can adapt to varying engine conditions, but the engine power output fluctuates and reduces in high-load range
Solution Approach 1:
The control system divides the engine operating range into two segments: high-load range and other ranges. In the high-load range, a predetermined valve operating characteristic is used, while in other ranges, the calculated characteristic based on target intake-air quantity is applied. This segmentation resolves the contradiction by avoiding disturbance-affected calculations when reliability is most critical.
Solution Approach 2:
The predetermined valve operating characteristic for high-load conditions is established in advance through optimization, rather than being calculated in real-time during operation. This preliminary action ensures that the most reliable, pre-validated parameters are used when the engine operates in the critical high-load range, preventing power output fluctuations.
2Quantity of substance
If the calculated target operating characteristic is used in high-load range, then the target intake-air quantity can be achieved, but the engine power output performance is compromised due to disturbance signals
Solution Approach 1:
The system dynamically selects between two different control strategies based on the current operating condition. When the engine is in the high-load range, it switches to the predetermined characteristic mode to ensure power performance. When operating in other ranges, it uses the calculated characteristic mode to achieve target intake-air quantity. This dynamic switching resolves the contradiction by applying the appropriate control method for each operating condition.
Data Source
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AI summary
In an intake-air quantity control system of an engine employing a variable valve operating device capable of controlling a cylinder intake-air quantity by variable control of an operating characteristic of an intake valve, in a normal intake-valve operating mode a target operating characteristic of the intake valve is determined based on a target cylinder intake-air quantity calculated based on a target engine torque. In a predetermined high-load range, in particular, at full-load operation, the target operating characteristic is switched to a high-load period valve operating characteristic, preset to be suitable for the predetermined high-load range.