Turbocharged Engine Intake Valve Timing and Exhaust Separation
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Solution Overview
Problem
Engines with high geometric compression ratios and turbochargers face preignition issues due to excessive compression and high in-cylinder temperatures, which reduce fuel efficiency and increase the risk of early self-ignition.
Innovation Solution
The engine design includes a geometric compression ratio of 11:1 or higher, a long intake valve open period of 270° or more, and multiple independent exhaust passages that communicate with non-consecutive cylinder exhaust ports, reducing in-cylinder temperature and preventing preignition by improving scavenging performance and minimizing exhaust interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the geometric compression ratio is increased to 14:1 or higher to improve fuel efficiency, then fuel efficiency is improved, but preignition occurs due to excessive compression and high in-cylinder temperature
Solution Approach 1:
The patent applies dynamic valve timing control by making the intake valve open period variable based on engine operating conditions. The open period is set to 270° or more in crank angle under certain conditions, which dynamically adjusts the effective compression ratio and in-cylinder temperature to prevent preignition while maintaining high fuel efficiency.
Solution Approach 2:
The patent changes the parameter of intake valve open period to 270° or more in crank angle, which fundamentally alters the compression process. This parameter change reduces the effective compression ratio and in-cylinder temperature, preventing preignition while allowing the geometric compression ratio to remain high for fuel efficiency.
2Power
If a turbocharger is provided to increase engine output, then engine output is increased, but in-cylinder temperature increases causing preignition
Solution Approach 1:
The patent uses dynamic adjustment of the intake valve open period (270° or more) to control in-cylinder temperature under turbocharged conditions. This dynamic control allows the engine to maintain high output from the turbocharger while preventing temperature-induced preignition.
Solution Approach 2:
The patent converts the potentially harmful effect of turbocharger-induced high temperature into a beneficial control mechanism. By using the long intake valve open period to manage temperature, the turbocharger's boosting capability is retained while its temperature side effect is controlled to prevent preignition.
3Reliability
If the intake valve close timing is retarded to reduce effective compression ratio, then preignition is suppressed, but scavenging performance deteriorates
Solution Approach 1:
The patent resolves this contradiction by making the intake valve open period dynamic (270° or more), which allows the close timing to be retarded for preignition suppression while the extended open period maintains adequate scavenging performance. The dynamic parameter adjustment balances both requirements.
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 enhances fuel efficiency while suppressing preignition, maintaining low in-cylinder temperatures, and efficiently driving the turbine with high exhaust energy, thus improving engine output and reducing size.
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
Implementation Method 3
The open period of the intake valve is a range of 270° or larger in crank angle... the effective compression ratio of the cylinder is lowered so that a mixture gas inside the cylinder is prevented from being excessively compressed
Implementation Method 4
The exhaust passage includes a plurality of independent exhaust passages, each communicating with the exhaust port of one cylinder or the exhaust ports of two or more cylinders of which timings of exhaust strokes are discontinuous from each other
Data Source
AI summary
An engine is provided, which includes an engine body including a plurality of cylinders, each of the cylinders being provided with an intake port, an exhaust port, an intake valve, and an exhaust valve, an intake passage and an exhaust passage connected to the engine body, and a turbocharger including a turbine provided to the exhaust passage and a compressor provided to the intake passage. A geometric compression ratio of the cylinder is 11:1 or higher. An open period of the intake valve is a range of 270° or larger by a crank angle. The exhaust passage includes a plurality of independent exhaust passages, each communicating with the exhaust port of one cylinder or with the exhaust ports of two or more cylinders of which timings of exhaust strokes are discontinuous from each other, and connecting the engine body to the turbine.