Thermal Coating for Spark-Ignition Engine Combustion Chamber
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Solution Overview
Problem
Internal combustion engines face efficiency losses due to heat transfer and the knocking phenomenon in spark ignition engines, where high temperatures lead to increased heat losses and premature knocking, requiring compensatory measures like turbochargers and reduced ignition advance, which affect engine efficiency.
Innovation Solution
A thermal coating is applied to the combustion chamber, extending radially from the center to 30-80% of the diameter, with varying thickness and materials, including thermal barrier and temperature swing effect coatings, to minimize heat transfer and maintain higher combustion chamber temperatures, while differentiating between intake and exhaust valve areas to manage heat exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thermal insulation coating is applied to maintain high combustion chamber temperature, then fuel combustion completeness is improved, but fresh gas heating during intake phase increases causing volumetric efficiency decrease
Solution Approach 1:
The patent applies thermal insulation coating selectively to specific zones of the combustion chamber rather than uniformly across all surfaces. The coating is applied to the roof and side walls where thermal insulation is most beneficial for maintaining combustion temperature, while deliberately leaving the piston crown and intake port areas uncoated or with minimal coating to prevent fresh gas heating and maintain volumetric efficiency.
2Loss of energy
If thermal insulation coating is applied to maintain high combustion chamber temperature, then combustion completeness is improved, but knocking phenomenon frequency increases
Solution Approach 1:
The patent implements zone-specific thermal insulation where the coating is applied to the combustion chamber roof and side walls to maintain high temperatures for complete combustion, but deliberately excludes the piston crown and intake areas from heavy insulation. This localized approach prevents excessive temperature buildup in areas that would trigger knocking, while still achieving the benefits of thermal insulation in the combustion zone.
Solution Approach 2:
The thermal insulation system is segmented into different zones with different coating thicknesses or materials. The combustion chamber roof receives full thermal insulation to maintain high temperatures, while the piston crown and intake ports have reduced or no insulation to prevent hot spots that cause knocking. This segmentation allows simultaneous achievement of combustion efficiency and knock prevention.
3Temperature
If thermal barrier coating is applied to reduce heat transfer to cooling circuit, then combustion chamber temperature is maintained higher, but fresh air filling is negatively impacted
Solution Approach 1:
The thermal barrier coating is applied selectively to the combustion chamber roof and side walls where high temperature maintenance is critical for combustion efficiency. The coating is deliberately avoided or minimized in the intake port and piston crown areas to ensure that fresh air can be filled without excessive heating, thereby maintaining both high combustion temperatures and adequate air filling quantity.
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 enhances engine efficiency by reducing heat loss and knocking risks, maintaining higher combustion temperatures for complete fuel combustion, and improving air filling efficiency without compromising engine performance.
Implementation Method 1
a thermal coating 40 is deposited on an upper surface 39 of a roof 38 of the combustion chamber 36 to form a thermal barrier and thus allow higher temperatures to be maintained within the combustion chamber 36
Implementation Method 2
at least one thermal coating is of the thermal barrier type
Implementation Method 3
at least one thermal coating is a material whose thermal effusivity is less than 500 WK -1[0013]The invention also provides a method for manufacturing a spark-ignition internal combustion engine comprising at least one step of depositing a thermal coating
Implementation Method 4
more complete combustion of fuel can be achieved in an internal combustion engine if higher temperatures can be maintained in the combustion chambers throughout the entire engine cycle
Implementation Method 5
The heat flux φ (W) passing through a wall of the combustion chamber by conduction is proportional to the thermal conductivity coefficient λ (W.nr -1[0005]A disadvantage of this type of coating is the increase in the average temperature of the coating during engine cycles
Implementation Method 6
The heat flux or thermal flux, denoted φ (W), by convection between the burnt gases resulting from combustion and a wall of the combustion chamber is equal to the product of the heat transfer coefficient H (Wm -2[0004]
Data Source
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AI summary
Spark-ignition internal combustion engine (12) comprising: - at least one cylinder (22) in which a piston (26) is mounted to slide, - at least two valve ports including an intake valve port (34) and an exhaust valve port, - a combustion chamber (36) delimited by the roof (38) of the combustion chamber (36), by a peripheral axial wall (24) and by the head of the piston (28); characterized in that at least one thermal coating (40) is deposited on an upper surface (39) of the roof (38) of the combustion chamber (36) opposite the head of the piston (28) to minimize heat transfers to parts outside the combustion chamber (36) and thus maintain a higher temperature inside the combustion chamber (36).