SPCCI Engine Vehicle Attitude Control via Regenerative Braking
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Solution Overview
Problem
In vehicles equipped with SPCCI combustion engines, changing ignition timing for vehicle attitude control can lead to unstable combustion and misfire, especially when the air-fuel ratio is lean, as self-ignition is less likely due to the lean mixture.
Innovation Solution
A vehicle system that includes a spark plug, a rotary electric machine, an operating state sensor, and a controller to control the engine and rotary electric machine, where the controller sets a target deceleration based on steering angle and adjusts air-fuel ratios and ignition timing to maintain combustion stability by using regenerative electric power generation instead of changing ignition timing during lean air-fuel ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ignition timing is changed for vehicle attitude control during SPCCI combustion, then vehicle attitude control is achieved, but combustion stability deteriorates and misfire occurs
Solution Approach 1:
The patent introduces a rotary electric machine as an intermediary device to achieve vehicle attitude control. Instead of directly changing ignition timing which affects combustion stability, the rotary electric machine generates deceleration force during regenerative braking to control vehicle attitude, particularly during lean air-fuel ratio combustion where ignition timing changes would cause misfire. This mediator approach allows attitude control while preserving combustion stability.
Solution Approach 2:
The patent changes the control parameter from ignition timing to rotary electric machine output. By controlling the regenerative braking force of the rotary electric machine instead of changing ignition timing, the system achieves vehicle attitude control without disrupting the combustion process, especially important during lean burn conditions where combustion is more sensitive to timing changes.
2Power
If ignition timing is retarded to generate deceleration for vehicle attitude control, then deceleration is achieved, but combustion efficiency deteriorates
Solution Approach 1:
The rotary electric machine serves as an intermediary to provide deceleration force without affecting combustion efficiency. During regenerative braking, the rotary electric machine converts kinetic energy to electrical energy while providing deceleration, thereby controlling vehicle attitude without retarding ignition timing and maintaining combustion efficiency.
Solution Approach 2:
The patent replaces the mechanical approach of retarding ignition timing to generate deceleration with an electrical/electromechanical approach using regenerative braking. The rotary electric machine provides the necessary deceleration force through electromagnetic braking and regenerative energy recovery, substituting the combustion-based deceleration method with an independent braking system that does not interfere with combustion efficiency.
3Loss of energy
If air-fuel ratio is set to lean side for fuel economy, then fuel consumption is reduced, but combustion stability deteriorates and misfire is more likely
Solution Approach 1:
The rotary electric machine acts as a mediator that enables the system to operate at lean air-fuel ratios for improved fuel economy while maintaining combustion stability. By providing deceleration control through regenerative braking instead of ignition timing adjustment, the system can sustain lean burn conditions without causing misfire, as the deceleration demand is met by the rotary electric machine rather than combustion modification.
Solution Approach 2:
The patent dynamically adjusts the control strategy based on operating conditions. During lean burn operation, the system prioritizes combustion stability by using regenerative braking for deceleration control. The control system dynamically switches between ignition timing control and rotary electric machine control depending on the air-fuel ratio and driving conditions, allowing lean operation to be maintained stably.
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 system effectively executes vehicle attitude control while ensuring combustion stability during SPCCI combustion, even at lean air-fuel ratios, by using regenerative power generation to generate deceleration without altering ignition timing, thus preventing misfires and improving fuel economy and emission performance.
Implementation Method 1
a part of an air-fuel mixture in a cylinder of the engine is combusted by spark ignition of the spark plug
Implementation Method 2
the remaining air-fuel mixture in the cylinder is combusted by self-ignition
Implementation Method 3
control a regenerative electric power generation of the rotary electric machine so as to generate the target additional deceleration in the vehicle
Data Source
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AI summary
A vehicle system comprises an engine 1, a motor-generator 114 and a controller 60. The engine 1 has a combustion mode in which a part of an air-fuel mixture is combusted by spark ignition, and then the remaining air-fuel mixture is combusted by self-ignition. The controller 60 sets a target additional deceleration based on a steering angle, when a steering wheel 105 is turned, and sets an air-fuel ratio of the air-fuel mixture to either one of a first air-fuel ratio and a second air-fuel ratio which is on a lean side, based on an operating state, when the engine 1 performs the combustion mode. The controller 60 controls an ignition timing so as to generate the target additional deceleration in the first air-fuel ratio, and controls a regenerative electric power generation of the motor-generator 114 so as to generate the target additional deceleration in the second air-fuel ratio.