Pre-Chamber Jet Ignition Spark Stagger for Accurate Torque Control
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Solution Overview
Problem
Existing methods for determining torque in turbulent jet ignition (TJI) engines fail to accurately account for both pre-chamber and secondary spark ignition timings, leading to inefficiencies in combustion quality and fuel economy.
Innovation Solution
A combustion control system and method that independently controls the pre-chamber and secondary spark timings using two ignition devices, determining a target spark stagger and adjusting maximum brake torque (MBT) to estimate actual torque based on delta spark and efficiency models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single spark plug ignition timing is used in TJI engines, then the control system is simple, but torque estimation accuracy deteriorates because both pre-chamber and secondary ignition timings are not accounted for
Solution Approach 1:
The ignition timing control is segmented into two independent components: pre-chamber spark timing and secondary spark timing. Each spark plug's timing is controlled separately through distinct timing parameters, allowing independent optimization of each ignition event while maintaining overall system manageability
Solution Approach 2:
The system introduces a spark stagger parameter that dynamically adjusts the timing difference between pre-chamber and secondary sparks based on engine operating conditions. This parameter change enables accurate torque estimation by accounting for the temporal relationship between the two ignition events without requiring complex hardware modifications
2Reliability
If both pre-chamber and secondary spark timings are controlled independently, then combustion quality improves, but the complexity of determining optimal spark timing increases
Solution Approach 1:
The system employs feedback from torque sensors and engine operating parameters to continuously adjust the pre-chamber and secondary spark timings. The controller monitors combustion outcomes and modifies the spark stagger and individual timing parameters to maintain optimal combustion quality across varying engine conditions
Solution Approach 2:
The pre-chamber spark timing is established first to initiate combustion, followed by the secondary spark timing that builds and completes the combustion event. This preliminary sequencing of ignition events creates a controlled combustion progression that improves reliability while simplifying the control strategy compared to simultaneous or random timing approaches
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
Enhances torque estimation accuracy by accounting for both ignition timings, improving combustion efficiency and fuel economy in TJI engines.
Implementation Method 1
Flame is initiated inside the pre-chamber and jets into the main combustion chamber to ignite the bulk fuel air mixture
Implementation Method 2
A second spark plug is mounted in an offset position in the main combustion chamber
Data Source
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AI summary
A combustion control system and method for a turbulent jet ignition engine is presented. A controller is configured to receive a torque request, determine a target spark stagger based on a first spark from a first ignition device and a second spark from a second ignition device, determine an adjusted maximum brake torque (MBT) based on the spark stagger, determine a delta spark based on a difference between the adjusted MBT and an actual leading spark from the first and second ignition devices, determine a torque efficiency based on the delta spark, estimate an actual torque, and command a first and a second spark timing from the first and second ignition devices to satisfy the torque request.