Miller Cycle Engine Port Communication for Pressure Loss Reduction
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Solution Overview
Problem
Internal combustion engines operating under the Miller cycle face pressure losses during the compression phase due to the open inlet port, which reduces efficiency as they must compress air against the pressure of a turbocharger.
Innovation Solution
The design incorporates at least two rotatable bodies with primary and secondary inlet ports and a conduit system that allows compressed air to be shared between combustion chambers, optimizing air distribution and reducing pressure losses by overlapping the intake and compression phases, thereby minimizing the pressure against which compression occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the inlet port is kept open during the beginning of the compression phase in a Miller cycle engine, then the volumetric compression ratio is reduced, but pressure losses occur during compression against the turbocharger pressure
Solution Approach 1:
The inlet port operation is segmented into two distinct phases: a first portion where the inlet port remains open during the beginning of compression to maintain Miller cycle benefits, and a second portion where the inlet port closes to enable effective compression. This segmentation allows the engine to capture pressure early in the compression stroke while avoiding the energy losses that would occur if the port remained open throughout the entire compression phase.
Solution Approach 2:
The inlet port closes at a predetermined timing during the compression phase, before the piston reaches top dead center. This preliminary closure action prepares the combustion chamber for effective compression by sealing the chamber at the optimal moment, ensuring that subsequent compression occurs against a closed volume rather than against the open inlet port and turbocharger pressure.
2Loss of energy
If the inlet port closes early during the compression phase, then pressure losses are reduced, but the volumetric compression ratio decreases
Solution Approach 1:
The inlet port closure timing is made dynamic rather than fixed, allowing it to vary based on operating conditions such as engine load, speed, and turbocharger pressure. This dynamic adjustment enables the control system to optimize the balance between maintaining volumetric compression ratio and minimizing pressure losses by closing the inlet port at the most appropriate moment for each specific operating condition.
Solution Approach 2:
The closure timing of the inlet port is changed as a variable parameter that can be adjusted independently of the geometric compression ratio. By changing the timing parameter of inlet port closure, the effective volumetric compression ratio can be optimized for each operating condition while minimizing pressure losses, decoupling the timing parameter from the fixed geometric design parameters.
3Stress or pressure
If a turbocharger is used to increase compression pressure, then the pressure compression ratio increases, but compression must be performed against higher pressure causing greater losses
Solution Approach 1:
The inlet port closes preliminarily during the compression phase, before the piston reaches top dead center and before the highest pressure conditions are reached. This preliminary closure allows the majority of the compression work to be performed on a sealed charge, significantly reducing the amount of work that must be done against the high turbocharger pressure that would otherwise be present throughout the entire compression stroke.
Solution Approach 2:
The inlet port closure occurs rapidly at a predetermined timing, effectively skipping the transition from open to closed state and avoiding the intermediate period where compression would occur against the open port and turbocharger pressure. This rapid closure action rushes through the critical transition phase, minimizing the time during which energy losses occur.
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 configuration enhances the efficiency of the Miller cycle engines by reducing pressure losses and improving air distribution, leading to better compression ratios and overall engine performance.
Implementation Method 1
a respective conduit providing a fluid communication between the at least one inlet port of the respective internal cavity of each of the bodies and the at least one inlet port of the respective internal cavity of the different one of the bodies
Implementation Method 2
each of the bodies being sealingly and rotationally received within the respective internal cavity to each define at least one combustion chamber of variable volume undergoing a cycle defining successive phases of intake, compression, combustion and exhaust
Implementation Method 3
compression phase of the at least one combustion chamber defined by each of the bodies being simultaneous with at least a beginning of the intake phase
Data Source
AI summary
An internal combustion engine including internal cavities slidingly receiving a respective piston to define a respective combustion chamber, at least one inlet port for each internal cavity in fluid communication with the combustion chamber at least during the intake phase and a beginning of the compression phase, at least one exhaust port for each of the internal cavities and in fluid communication with the combustion chamber during the exhaust phase, a plenum for receiving pressurized air, and conduits in fluid communication with the plenum. Each conduit defines a fluid communication between a first respective internal cavity and a second respective internal cavity through the inlet ports. The combustion chamber of the first respective internal cavity undergoes the beginning of the compression phase simultaneously with the combustion chamber of the second respective internal cavity undergoing the beginning of the intake phase.