Engine Controller Tumble Flow Shape Reversal for Lean Burn Ignition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional controllers for internal combustion engines face challenges in maintaining stable ignition during lean burn operations due to varying gas flow velocities around the sparkplug, especially at low fuel concentrations and high engine rotation speeds, leading to misfire and combustion instability.
Innovation Solution
A controller that adjusts the shape of tumble flow between a first and second tumble shape based on engine rotation speed, altering the gas flow direction and velocity around the sparkplug to maintain optimal ignition conditions, utilizing an electronic control unit to manage the intake and exhaust valves and the tumble flow control valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tumble flow is generated inside the cylinder during lean burn operation, then combustion efficiency is improved, but gas flow velocity around the sparkplug becomes too high or too low making stable ignition difficult
Solution Approach 1:
The patent applies the dynamics principle by making the tumble flow shape changeable during the compression stroke. The electronic control unit dynamically adjusts the tumble flow from a first shape (with single rotation direction) to a second shape (with opposite rotation direction) based on engine rotation speed. This dynamic adjustment allows the gas flow velocity around the sparkplug to be controlled within an appropriate range, maintaining ignition stability while preserving combustion efficiency improvements from tumble flow generation.
2Power
If engine rotation speed increases, then power output is improved, but gas flow velocity around the sparkplug increases making ignition unstable
Solution Approach 1:
The patent applies parameter changes by altering the tumble flow shape parameter based on engine rotation speed. When engine rotation speed is high, the electronic control unit changes the tumble flow to the second shape with opposite rotation direction, which reverses the gas flow direction around the sparkplug. This parameter change compensates for the increased gas flow velocity due to higher engine speed, maintaining stable ignition while allowing the engine to operate at high power output.
3Reliability
If tumble flow shape is changed to control gas flow velocity, then ignition ability is improved, but control system complexity increases
Solution Approach 1:
The patent applies universality by using the existing tumble control valve and electronic control unit to achieve multiple functions: maintaining combustion efficiency through tumble flow generation and controlling ignition stability through tumble flow shape change. The same control system infrastructure is utilized for both purposes, avoiding the need for additional dedicated components and minimizing control system complexity while improving ignition ability.
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 approach ensures stable ignition by controlling gas flow velocity around the sparkplug within a suitable range for lean burn operations, regardless of engine rotation speed, thereby improving ignition ability and reducing torque fluctuations.
Implementation Method 1
a tumble flow control valve that generates tumble flow inside a cylinder
Implementation Method 2
a sparkplug disposed in the vicinity of a center portion of an upper wall surface of a combustion chamber and serving to ignite an air-fuel mixture
Implementation Method 3
the electronic control unit is configured to change a shape of the tumble flow between a first tumble shape and a second tumble shape according to an engine rotation speed
Data Source
AI summary
Provided is an internal combustion engine including a sparkplug disposed in the vicinity of the center portion of an upper wall surface of a combustion chamber. Tumble flow generated during lean burn operation is controlled such that the tumble flow shape changes according to the engine rotation speed between a first tumble shape (usual tumble shape) in which the flow direction of a gas around the sparkplug at the time of ignition is direction from an intake valve side toward an exhaust valve side in a latter half of a compression stroke, and a second tumble shape (ω tumble shape) in which the flow direction of the gas is reversed in the latter half of the compression stroke from the direction from the intake valve side toward the exhaust valve side to the direction from the exhaust valve side toward the intake valve side.