Variable Cam Phasing for Miller Cycle Diesel Engine Load Response
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Solution Overview
Problem
Conventional diesel engines operating in the Miller cycle can only utilize its advantages in a limited load range and face inferior response to increasing load requirements, limiting their effectiveness in heavy vehicles and ships.
Innovation Solution
A device that controls the internal combustion engine by adjusting the phase between the camshaft rotation and intake valve closure, allowing the intake valve to close 20° to 45° before BDC in a second load range, and switching off the Miller cycle during load increases, while using a pump cam to control the injection pump's operation, ensuring efficient air charging and torque response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the Miller cycle is used to close the intake valve 20° to 45° before BDC, then nitrogen oxide emissions are reduced and peak combustion temperatures are decreased, but the response to increasing load requirements deteriorates
Solution Approach 1:
The patent applies dynamics by making the valve timing adjustable rather than fixed. The camshaft is designed with variable cam phasing capability, allowing the intake valve closing timing to be dynamically changed based on load conditions. In partial load conditions, the valve closes 20° to 45° before BDC to reduce NOx emissions, while in high load conditions, the timing can be advanced to improve response speed and torque delivery.
Solution Approach 2:
The patent changes the timing parameter of the intake valve closure based on operating conditions. By varying the camshaft phase angle, the system transitions between different valve closing timings (20°-45° before BDC for low load, earlier closure for high load), thereby optimizing both emissions and performance across the operating range.
2Temperature
If the intake valve closes early in the Miller cycle, then geometrical compression is maintained high while peak temperatures are decreased, but the load range for effective operation is limited
Solution Approach 1:
The system uses dynamic cam phasing to adjust valve timing based on load requirements. The variable valve timing mechanism allows the engine to operate effectively across a broader load range by adapting the intake valve closure timing, rather than being restricted to a fixed Miller cycle timing optimized only for partial load conditions.
Solution Approach 2:
The camshaft design provides multi-functionality by incorporating variable phasing capability that enables the same camshaft to deliver both Miller cycle operation (for emissions reduction) and conventional timing (for high load performance), making the system adaptable to diverse operating conditions without requiring multiple specialized camshafts.
3Quantity of substance
If variable valve operation is used to increase charged air mass during load demand, then the Miller cycle advantages can be extended, but the device complexity increases
Solution Approach 1:
The patent merges the variable valve timing control with the existing camshaft-driven valve operating mechanism. By integrating the phase adjustment capability into the camshaft itself rather than using a separate complex valve actuation system, the design reduces overall system complexity while still achieving variable charged air mass delivery.
Solution Approach 2:
The variable cam phasing mechanism acts as an intermediary between the crankshaft and the intake valve, allowing indirect control of valve timing through camshaft phase adjustment. This intermediary approach simplifies the control architecture compared to direct variable valve actuation systems while still achieving the desired effect of increasing charged air mass during load demand.
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
Enables the diesel engine to operate efficiently across a broader load range, improving torque response and reducing nitrogen oxide emissions by optimizing valve timing and injection timing, thus addressing the limitations of the Miller cycle in high-load conditions.
Implementation Method 1
a camshaft provided with an intake cam and rotationally driven by a crankshaft... the pump cam driving a pump piston of an injection pump via a pump operating arrangement in a reciprocating manner
Data Source
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AI summary
The present disclosure refers a method and device for controlling the operation of an internal combustion engine. The internal combustion engine is provided with at least one piston/cylinder unit having at least one intake valve, and is operating in a first load range and in a second load range, the second load range being higher than the first load range. The method comprises at least the step of, in the second load range of the internal combustion engine, closing the intake valve in a range of 20° to 45° before a BDC of the piston, according to a Miller cycle, and switching off the operation according to the Miller cycle at least during a part of a load increase within the second load range.