Piston Flow Guide Groove for Stable Tumble and Squeeze Combustion
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Solution Overview
Problem
The airflow in the combustion chamber of an engine becomes unstable near the compression top dead center, leading to unstable flame propagation and high gas consumption due to the asymmetrical arrangement of the tumble flow and squeezing airflow.
Innovation Solution
A combustion device with a piston design featuring a flow guide groove on the squeezing surface, symmetrically arranged notches, and a canopy cylinder head to stabilize the airflow, forming symmetrical offset forces and reducing instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a symmetrical tumble flow air passage and canopy cylinder head are used to improve tumble ratio and accelerate flame propagation, then combustion efficiency is improved, but the airflow becomes unstable near compression top dead center and cycle changes greatly
Solution Approach 1:
The patent introduces asymmetrical design elements including an asymmetrical piston pit configuration and a flow guide groove with non-symmetrical notch arrangement. These asymmetrical features create targeted airflow patterns that counteract the instability caused by the symmetrical tumble flow system, particularly near the compression top dead center where airflow becomes unstable.
Solution Approach 2:
The flow guide groove is strategically positioned on the piston surface at a specific location where airflow instability occurs. The groove includes notches that are asymmetrically arranged to create localized airflow modification only in the critical region, leaving the overall symmetrical tumble flow structure intact while addressing the local stability issue.
2Productivity
If squeezing flow is used to accelerate flame propagation and reduce soot, then combustion performance is improved, but the asymmetrical arrangement of squeezing airflow against tumble flow causes unstable flame propagation and high gas consumption
Solution Approach 1:
The flow guide groove acts as an intermediary structure between the squeezing airflow and the tumble flow. It mediates the interaction between these two airflow systems by creating a transition zone that harmonizes their conflicting directions, reducing the instability caused by their asymmetrical arrangement and preventing energy loss.
Solution Approach 2:
The asymmetrical notch configuration in the flow guide groove is designed to preemptively counteract the destabilizing effect of the squeezing airflow's asymmetrical arrangement. By pre-positioning these structural features, the patent prevents instability and energy loss before they occur during the compression and combustion processes.
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
The solution stabilizes the combustion process, reduces cycle variation, improves thermal efficiency, and decreases the tendency of knocking by ensuring stable airflow and symmetrical airflow organization.
Implementation Method 1
Squeezing flow, an airflow organization form, is widely used in gasoline engines. In the later stage of a compression process, the radial or transverse airflow movement generated when a certain part of the piston surface and the cylinder head are close to each other may increase the turbulence kinetic energy of the mixture airflow.
Implementation Method 2
a combination of a tumble flow air passage and a canopy cylinder head is used to improve the tumble ratio and accelerate flame propagation
Implementation Method 3
the radial or transverse airflow movement generated when a certain part of the piston surface and the cylinder head are close to each other may increase the turbulence kinetic energy of the mixture airflow
Implementation Method 4
Natural gas, which is often used as an alternative fuel for internal combustion engines
Data Source
AI summary
A combustion device for an engine and a method for designing a piston includes a cylinder head, a cylinder block cooperating with the cylinder head, and a piston disposed in the cylinder block. The cylinder head includes an intake valve setting region and an exhaust valve setting region. The surface of the piston adjacent to the cylinder head includes a first concave surface and a squeezing surface adjacent to the first concave surface. The squeezing surface includes a first squeezing surface corresponding to the intake valve setting region and a second squeezing surface corresponding to the exhaust valve setting region. A combustion chamber is formed between the first concave surface and the cylinder head. The second squeezing surface includes a flow guide groove. The flow guide groove includes two first notches facing the combustion chamber.