Turbo Compound Engine Crankcase Pressure Reduction
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Solution Overview
Problem
Spark ignited Otto Cycle throttled internal combustion engines suffer from parasitic pumping losses due to pressure imbalances during the intake cycle, leading to increased specific fuel consumption and anthropogenic emissions, particularly at part-load operations, and existing solutions like diesel engines or turbo-compound systems are costly, complex, and inefficient.
Innovation Solution
A closed-loop pneumatic coupling crankcase pressure reduction system that synchronizes the pressure cycles in individual cylinder crankcases using evacuation and expansion conduits and valves, neutralizing the pressure differential on the piston during the intake cycle without altering the cylinder charging integrity or stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a throttled Otto cycle engine operates at part-load, then the engine can reduce power output, but parasitic pumping losses increase due to pressure imbalance in the crankcase
Solution Approach 1:
The crankcase is divided into multiple individually partitioned volumes, each corresponding to a cylinder. This segmentation allows independent pressure control in each crankcase volume, enabling the system to address pumping losses in each cylinder separately while maintaining overall engine operation at part-load conditions.
Solution Approach 2:
The invention employs pneumatic coupling through evacuation and expansion conduits to create pressure balance in the crankcase volumes. By using pneumatic pressure differentials and controlled gas flow, the system neutralizes the harmful pressure imbalance that causes pumping losses during part-load operation.
2Loss of energy
If a turbo-compound system is used to reduce pumping losses, then energy recovery improves, but the system becomes heavier and more complex
Solution Approach 1:
The individually partitioned crankcase volumes serve multiple functions: they contain the piston, provide pressure balance to reduce pumping losses, and enable synchronized evacuation and expansion operations. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall system complexity while maintaining energy recovery capabilities.
Solution Approach 2:
The system uses the engine's own operating cycle to drive the evacuation and expansion operations. The piston movement and pressure differentials generated during normal engine operation are harnessed to create the necessary pressure balance, eliminating the need for external power sources or complex control systems.
3Loss of energy
If existing crankcase pressure equalization systems are used, then some pumping losses are reduced, but the pressure imbalance is not fully eliminated
Solution Approach 1:
The synchronized evacuation and expansion operations create a feedback mechanism where pressure changes in one crankcase volume directly influence the pressure balance in other volumes. This feedback loop ensures continuous pressure equalization and maintains stable pressure balance throughout the engine cycle, fully eliminating the harmful pressure imbalance.
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 system effectively reduces pumping-loss friction, improving fuel efficiency and emission reduction, allowing for extended engine operation ranges without altering the stoichiometric air-fuel mixture, and is cost-effective, making it suitable for retrofitting existing engines.
Implementation Method 1
A pump is provided to evacuate the air volumes of the individually partitioned cylinder crankcases
Implementation Method 2
displaced to an air volume of an individually partitioned cylinder crankcase undergoing an exhaust stroke when the expansion valve (66) of the individually partitioned cylinder crankcase undergoing an exhaust stroke is simultaneously open
Implementation Method 3
at least two synchronized evacuation valves (64) disposed between the individually partitioned cylinder crankcases (46, 48, 50, 52) and the evacuation conduits (54), the evacuation valves (64) being operable between an open position for allowing air flow from the individually partitioned cylinder crankcases (46, 48, 50, 52) and into the evacuation conduits (54)
Data Source
AI summary
Otto intake-cycle controlled-air (throttled) internal combustion engines suffer from parasitic pumping losses associated with partial vacuums developed in their intake manifolds and in the cylinders above their pistons. To solve this problem, there is provided individually partitioned dry-sump crankcases dynamic pneumatic coupling pressure reduction cycle system and method that reduce the damaging parasitic effects of the differential pressure about a piston head during an intake cycle which is a source of part-load pumping-loss friction. This closed loop system includes an independent supplemental mechanical fail-safe system of a turbo-compound engine variant for pneumatic coupling of individual cylinder-crankcase volumes. It does not alter the cylinder homogeneous mixture charge integrity and stability. The system is applicable to several engine configurations, such as controlled air intake or uncontrolled air intake combustion engines, using different fuel types, either in liquid or in gazeous state.