Variable Intake Valve Timing for Turbocharged Engine Knock Suppression
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Solution Overview
Problem
Engines with high geometric compression ratios and turbochargers face issues with abnormal combustion, such as preignition and knocking, due to high engine loads and temperatures, which compromise fuel efficiency and performance.
Innovation Solution
A variable phase mechanism that adjusts the intake valve's open and close timings to maintain an open period of 270° or larger, with the intake valve closing after the intake bottom dead center and opening before the exhaust valve, while setting the geometric compression ratio to 11:1 or higher, to create an effective compression ratio that suppresses preignition and knocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the geometric compression ratio is increased to improve fuel efficiency, then fuel efficiency is improved, but abnormal combustion (preignition and knocking) easily occurs
Solution Approach 1:
The patent applies variable valve timing to dynamically adjust the intake valve closing timing based on operating conditions. By retarding the intake valve closing timing in high-load conditions, the effective compression ratio is reduced dynamically, preventing preignition and knocking while maintaining the high geometric compression ratio for fuel efficiency during normal operation
Solution Approach 2:
The patent changes the timing parameter of the intake valve closing to control the effective compression ratio. By adjusting the intake valve closing timing relative to bottom dead center, the patent effectively modifies the compression process to prevent abnormal combustion while maintaining high geometric compression ratio benefits
2Reliability
If the intake valve closes after intake bottom dead center to lower effective compression ratio and suppress knocking, then abnormal combustion is suppressed, but the open period of the intake valve must be extended to maintain scavenging performance
Solution Approach 1:
The patent uses a variable valve timing mechanism that can dynamically adjust the intake valve timing across a wide range. This dynamic capability allows the system to extend the intake valve open period when needed while maintaining precise control over the closing timing to achieve the desired effective compression ratio and suppress abnormal combustion
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves fuel efficiency and reduces the occurrence of abnormal combustion by lowering the effective compression ratio and enhancing scavenging performance, ensuring efficient engine operation even at high loads.
Implementation Method 1
a turbocharger including a turbine provided to the exhaust passage and a compressor provided to the intake passage
Implementation Method 2
a turbocharger including a turbine provided to the exhaust passage and a compressor provided to the intake passage
Data Source
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AI summary
An engine is provided, which includes an engine body including a cylinder provided with intake and exhaust ports and intake and exhaust valves, intake and exhaust passages, a turbocharger including a turbine provided to the exhaust passage and a compressor provided to the intake passage, and a variable phase mechanism configured to change open/close timings of the intake valve while maintaining an open period of the intake valve at a 270°CA or larger. A geometric compression ratio of the cylinder is 11:1 or higher. In a high-load range, the variable phase mechanism sets the intake valve close timing to be after an intake BDC and to make a ratio of a retarded amount of the intake closing to the geometric compression ratio be 4.58 or above and 6.67 or below, and sets the intake valve open timing to be before a close timing of the exhaust valve.