Asymmetric Twin Scroll Volute for Engine Backpressure Reduction
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Solution Overview
Problem
Turbocharger backpressure and pressure differentials at the turbocharger outlet and exhaust inlet are not adequately minimized, leading to reduced fuel economy and potential engine self-ignition due to uneven peak pressures and pulsations across cylinder sets.
Innovation Solution
An asymmetric twin scroll turbine volute design combined with an integrated exhaust manifold cylinder head, where one volute is larger in volume and flow capacity than the other, balances gas flow and pressures between cylinder sets, reducing the turbine pressure differential and minimizing backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional symmetric twin scroll volute is used, then the structure is simple and easy to manufacture, but the peak pressures and pulsations are uneven across cylinder sets, causing increased backpressure and potential engine self-ignition
Solution Approach 1:
The patent applies asymmetry by designing the twin scroll volute with unequal scroll dimensions. The first scroll has a larger cross-sectional area and different geometry compared to the second scroll, allowing each scroll to be optimized for its specific cylinder bank's exhaust flow characteristics. This asymmetric design equalizes peak pressures across all cylinders and prevents self-ignition while maintaining a relatively simple manufacturing process.
2Productivity
If a larger volute is used to increase flow capacity, then the mass flow capacity increases, but the device size and volume increase
Solution Approach 1:
The patent applies local quality by giving each scroll different dimensions and cross-sectional areas optimized for its specific function. The first scroll has larger dimensions to handle higher flow demands from certain cylinder banks, while the second scroll is smaller. This localized optimization increases overall mass flow capacity without requiring a uniform increase in the entire volute volume.
3Use of energy by moving object
If the turbine pressure differential is reduced to minimize backpressure, then fuel economy improves, but the turbine power output may be reduced
Solution Approach 1:
The asymmetric volute design dynamically balances the exhaust gas flow distribution between the two scrolls, allowing the system to adapt to varying engine operating conditions. By equalizing peak pressures across cylinders through optimized scroll geometry, the system maintains lower backpressure across a wider range of operating conditions, improving fuel economy while preserving adequate turbine power through the dynamic balancing of flow distribution.
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 solution effectively reduces engine backpressure, prevents engine self-ignition, and improves fuel economy by evenly distributing peak pressures and pulsations across all cylinders, enhancing the efficiency and reliability of the engine operation.
Implementation Method 1
The amount of work that can be done across an exhaust turbine is determined by the pressure differential at the turbine inlet and turbine outlet. The turbine creates an additional pressure differential, elevating turbine inlet pressure above that of the turbine outlet.
Implementation Method 2
Exhaust gas flows from the chamber, scroll or volute through the nozzle to the turbine wheel and the turbine wheel is driven by the exhaust gas.
Data Source
AI summary
An asymmetric twin scroll turbine 10 combined with an integrated exhaust manifold cylinder head 20 may be designed to accommodate mixed, radial or axial flow turbines. The asymmetric twin scroll turbine 10 includes a first scroll 11 and second scroll 12 wherein the first scroll 11 is larger and has greater mass flow capacity than the second scroll 12. The larger volute increases flow capacity and counteracts backpressure creating evenly balanced or equalized peak pressures and pulsations between both volutes and balancing of gas flow between cylinder sets. By equalizing peak pressures, pulsations, and gas flow between cylinder sets, engine self-ignition can be avoided in the cylinder set that would have had the largest peak pressures and pulsations. By in creasing flow capacity of the larger volute and balancing gas flow between cylinder sets, the turbine pressure differential is reduced and the engine can operate more efficiently, improving fuel economy.