Internal Combustion Engine Hot Start Knocking via HCCI
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Solution Overview
Problem
Internal combustion engines with spark ignition experience knocking during 'hot' starts due to high inlet air temperature and pressure, leading to undesirable behavior such as noise, vibration, and reduced torque.
Innovation Solution
Operating the engine in a controlled self-ignition mode without spark ignition, utilizing homogeneous charge compression ignition (HCCI) or controlled auto-ignition (CAI), where the fuel-air mixture is lean or gradually richer, and controlling the throttle valve to reduce pressure and temperature, thereby minimizing knocking and increasing torque delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is started using conventional spark ignition procedure after being stopped, then the engine can start quickly, but knocking occurs due to high inlet air temperature and pressure
Solution Approach 1:
The invention changes the combustion mode parameter from spark ignition to controlled self-ignition (HCCI/CAI) during hot start conditions. This parameter change allows the engine to avoid knocking by using a different ignition mechanism that is less sensitive to high inlet air temperature and pressure, while still achieving quick torque delivery.
Solution Approach 2:
The invention dynamically switches between different combustion modes based on engine operating conditions. The control system monitors inlet air temperature and pressure, and automatically transitions from conventional spark ignition to controlled self-ignition mode when hot start conditions are detected, providing adaptive optimization of the start procedure.
2Object-affected harmful factors
If controlled self-ignition mode is used during hot start, then knocking is reduced, but the complexity of the control system increases
Solution Approach 1:
The control system uses feedback from sensors monitoring inlet air temperature and pressure to determine when to switch between combustion modes. This feedback mechanism allows the system to automatically adapt to hot start conditions and switch to controlled self-ignition mode only when necessary, minimizing unnecessary complexity while effectively preventing knocking.
Solution Approach 2:
The controlled self-ignition mode utilizes the natural auto-ignition properties of the fuel-air mixture under specific temperature and pressure conditions, rather than requiring external spark ignition. This self-service approach reduces the need for complex ignition timing control while still achieving reliable combustion and knocking prevention.
3Object-affected harmful factors
If a lean fuel-air mixture is used in controlled self-ignition mode, then knocking is reduced and NVH levels are improved, but torque delivery may be reduced
Solution Approach 1:
The invention uses periodic alternation between different combustion modes during the start procedure. Controlled self-ignition with lean mixture is used for initial cycles to establish stable combustion and reduce knocking, followed by transition to spark ignition mode to quickly build up torque. This periodic switching optimizes both knocking reduction and torque delivery characteristics.
Solution Approach 2:
The fuel-air mixture ratio is dynamically adjusted based on the combustion phase and engine speed. During controlled self-ignition mode, a leaner mixture is used to reduce knocking and NVH. As the engine transitions to spark ignition mode and speed increases, the mixture is enriched to maximize torque delivery, providing dynamic optimization of the power-knocking trade-off.
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
Effectively reduces knocking and noise while maintaining quick torque delivery during hot starts, with reduced NOx emissions and improved noise, vibration, and harshness (NVH) levels.
Implementation Method 1
the homogeneous charge compression ignition (HCCI), or controlled auto-ignition (CAI)
Implementation Method 2
the homogeneous charge compression ignition (HCCI), or controlled auto-ignition (CAI)
Implementation Method 3
controlling the throttle valve to reduce pressure and temperature
Implementation Method 4
the pressure rise per crank-angle degree is reduced. Also, the low amount of fuel causes the load, hence the maximum cylinder pressure level, to reduce
Data Source
AI summary
The description relates to an internal combustion engine, and a method for an internal combustion engine with at least one cylinder, at each of which at least one spark providing device for ignition being provided. The engine is operated, in connection to a start procedure of the engine, in a controlled self-ignition mode comprising at least one controlled combustion without spark ignition. The controlled combustion without spark ignition can comprise homogeneous charge compression ignition (HCCI).