Variable Compression Ratio Engine Response via Exhaust Promotion
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Solution Overview
Problem
The existing variable compression ratio internal combustion engines face difficulties in obtaining a sufficient response when switching from a low to a high compression ratio due to the inertial force being far smaller than the explosive force, particularly at low engine speeds, leading to deteriorated response performance.
Innovation Solution
A variable compression ratio internal combustion engine equipped with a variable length connecting rod mechanism and an exhaust promotion mechanism, where the control device operates the exhaust promotion mechanism during the transition from demanding a higher mechanical compression ratio to its completion, utilizing the turbocharger or electric turbine to enhance negative pressure and assist in raising the compression ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a variable length connecting rod mechanism is used to change compression ratio, then the mechanical compression ratio can be switched between high and low ratios, but the response when raising compression ratio is insufficient due to inadequate inertial force
Solution Approach 1:
The exhaust promotion mechanism is activated in advance during the transition period before the compression ratio change is completed. By reducing cylinder residual gas and enhancing negative pressure beforehand, the system prepares favorable conditions that assist the connecting rod mechanism in achieving faster compression ratio switching, particularly when transitioning from low to high compression ratio.
2Use of energy by moving object
If the engine operates at low speed, then fuel consumption is reduced, but the inertial force becomes insufficient leading to deteriorated response performance
Solution Approach 1:
The exhaust promotion mechanism acts as an intermediary that compensates for the insufficient inertial force at low engine speeds. By actively managing exhaust gas removal and creating enhanced negative pressure, it provides the additional force needed to achieve adequate response speed during compression ratio switching, allowing the engine to maintain good responsiveness even when operating at low speeds with reduced fuel consumption.
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 solution improves the response when raising the mechanical compression ratio by increasing negative pressure inside the cylinders, thereby enhancing the mechanical compression ratio transition efficiency.
Implementation Method 1
utilizing the turbocharger or electric turbine to enhance negative pressure and assist in raising the compression ratio
Implementation Method 2
if the effective length of a connecting rod becomes longer, a combustion chamber volume when the piston is at top dead center of the compression stroke becomes smaller, and therefore the mechanical compression ratio increases
Implementation Method 3
the eccentric member pivots in one direction due to the upward inertial force acting on the piston pin due to the reciprocating motion of the piston
Implementation Method 4
the eccentric member pivots in the other direction due to the downward inertial force acting on the piston pin due to the reciprocating motion of the piston and the downward explosive force acting on the piston pin due to combustion of the air-fuel mixture
Data Source
AI summary
The variable compression ratio internal combustion engine 1 comprises: a variable compression ratio mechanism 6 able to change a mechanical compression ratio; an exhaust promotion mechanism 50, 55 able to reduce cylinder residual gas after an exhaust stroke of cylinders; and a control device 80 configured to control the mechanical compression ratio by the variable compression ratio mechanism and control an operation of the exhaust promotion mechanism. The control device is configured to operate the exhaust promotion mechanism in at least a partial time period of a time period from when it is demanded that the mechanical compression ratio be raised to when the mechanical compression ratio finishes being changed.