Cam Switch Timing Control for Engine Fuel Efficiency
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Solution Overview
Problem
Conventional internal combustion engine systems face challenges in reducing fuel consumption during cam switch operations in multi-cylinder engines, leading to increased fuel consumption and engine restart failures due to prolonged engine driving periods.
Innovation Solution
An internal combustion engine system with multiple cylinders, featuring two types of intake cams and self-holding type solenoids, where the control device outputs a switch request for the drive cams and stops the engine at a predetermined timing before the final cam carrier's slide operation begins, allowing for efficient cam switching and reduced fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine keeps driving for a predetermined period to complete the cam switch before engine restart, then the cam switch can be completed reliably, but the fuel consumption increases due to prolonged engine driving
Solution Approach 1:
The control device starts the protrusion operation of pins engaged with final cam carriers before the engine stop is executed. This preliminary action ensures that the cam switch is initiated in advance, allowing the engine to be stopped earlier while still completing the cam switch reliably, thus reducing fuel consumption during engine operation.
2Use of energy by moving object
If the cam switch is performed after engine restart, then the engine driving period is shortened, but engine start failure may occur due to delay
Solution Approach 1:
The system performs the protrusion operation of pins and cam carrier sliding before engine stop, ensuring the cam switch is completed or initiated before the engine shuts down. This preliminary timing prevents any delay that could cause engine start failure, while allowing the engine to be stopped as early as possible to minimize fuel consumption.
3Use of energy by moving object
If the protrusion operation of pins is delayed, then the engine can be stopped earlier, but the cam switch may not be completed reliably
Solution Approach 1:
The control device is configured to start the protrusion operation of pins engaged with final cam carriers before engine stop execution. This timing ensures that the cam switch process is initiated while the engine is still running, providing sufficient time for reliable completion before the engine shuts down, thereby maintaining both reliability and fuel efficiency.
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 minimizes fuel consumption by optimizing the timing of engine stop and cam switching operations, ensuring efficient engine restarts and reducing fuel usage during the cam switch process.
Implementation Method 1
the actuators are self-holding type solenoids which are configured to cause the pins to protrude by energizing an exciting coil
Data Source
AI summary
When a stop request to the engine is issued, it is determined whether or not all of the drive cams are large cams. When it is determined that at least one of the small cams is included in the drive cams, the engine is continued to drive for a while and a switch control for switching the drive cams from the small cams to the large cams is executed within the duration. A self-holding type solenoid is used to switch between the small cams and the large cams. In the switch control, a permission to stop the engine is output at a timing when the “pin protrudable section” of the final cylinder #2 has elapsed.