Nozzle Combustion Shield Thermal Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Spark-ignition engines face challenges in managing the temperature of fuel injectors to prevent pre-ignition events, as existing designs often result in inadequate heat transfer and difficulty in servicing due to threaded connections that can seize up over time.
Innovation Solution
A nozzle combustion shield (NCS) with a higher thermal conductivity than the injector tip is used in a non-threaded press fit configuration, providing a separate heat transfer path to the cylinder head and facilitating easy servicing by eliminating threaded engagements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a threaded injector tip is used to transfer heat to the cylinder head, then heat transfer is improved, but serviceability deteriorates due to seizing over time
Solution Approach 1:
The injector assembly is segmented into distinct components: the injector tip, the nozzle combustion shield (NCS), and the chamber housing. The NCS acts as an intermediate component that provides both thermal management and easy removal. This segmentation allows the heat transfer function to be separated from the mounting function, enabling the injector tip to be removed without dealing with seized threads.
Solution Approach 2:
The nozzle combustion shield serves as an intermediary component between the injector tip and the cylinder head. It provides a non-threaded press fit connection that facilitates easy removal while maintaining adequate heat transfer from the injector tip to the cylinder head. The NCS mediates between the thermal management requirement and the serviceability requirement.
2Ease of repair
If a non-threaded press fit configuration is used for the NCS, then serviceability is improved, but heat transfer may be insufficient
Solution Approach 1:
The system uses composite material properties where the NCS is made of a material with higher thermal conductivity than the chamber housing. This ensures that even with a non-threaded press fit connection, the heat transfer path remains effective. The composite structure of injector tip + NCS + cylinder head creates multiple thermal pathways.
Solution Approach 2:
The thermal conductivity parameter is optimized by selecting materials with appropriate properties. The NCS has a higher thermal conductivity than the chamber housing, ensuring adequate heat transfer. The press fit configuration parameters (interference fit, contact pressure) are designed to maintain good thermal contact while allowing easy removal.
3Temperature
If the NCS has higher thermal conductivity than the chamber housing, then heat transfer is improved, but device complexity increases
Solution Approach 1:
The nozzle combustion shield performs multiple functions simultaneously: it provides structural support, facilitates heat transfer, enables easy removal of the injector tip, and seals the combustion chamber. By consolidating these functions into a single component, the overall device complexity is managed despite using specialized materials.
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 NCS effectively manages heat transfer from the injector tip to the cylinder head, reducing the risk of pre-ignition events and simplifying maintenance by avoiding threaded connections that can seize, ensuring efficient cooling and easy assembly/disassembly.
Implementation Method 1
The NCS has a second thermal conductivity greater than the first thermal conductivity of the chamber housing
Implementation Method 2
The NCS inner surface is in a press fit configuration with the chamber housing
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus and method are disclosed for an injector assembly including an injector tip having a prechamber, such as a permanent, passive prechamber (PPPC), and a nozzle combustion shield (NCS) to mitigate pre-ignition events, such as knocking, caused by overheating of the prechamber. The NCS has a thermal conductivity greater than the injector tip. The NCS optionally includes a barrel forming a slip fit with the cylinder head bore and forming a press fit with the injector tip. The NCS also optionally includes a brim to form a combustion seal with a cylinder head. As the spark plug ignites a fuel charge in the prechamber, heat is absorbed into the injector tip, flows into the NCS barrel, out of the NCS brim, and into the cylinder head for cooling via a cooling jacket.