Supercharger Backflow Ports for Thermal Management

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Solution Overview

Problem

Roots type superchargers face thermal inefficiencies due to backflow and air leakage, leading to increased discharge temperatures that can cause engine damage and reduce performance, with existing methods struggling to optimize backflow slot sizing, placement, and geometry for minimal operating temperature and maximum efficiency.

Innovation Solution

An axial inlet, radial outlet supercharger system that introduces cooled air from an intercooler for backflow, using strategically designed backflow ports to manage air flow and reduce temperature, thereby increasing pressure ratio and efficiency while minimizing thermal limitations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooled air is introduced for backflow to reduce operating temperature, then outlet temperature decreases and pressure ratio increases, but device complexity increases due to additional intercooler integration and backflow port design

Engineering Contradiction:
Improveoutlet temperatureVSAvoiddevice complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent combines the intercooler and supercharger into an integrated system where the intercooler serves dual purposes: cooling the discharged air and providing cooled air for backflow to the supercharger inlet. This merging eliminates the need for separate cooling systems and reduces overall device complexity while achieving lower outlet temperatures and higher pressure ratios.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces cooled air as an intermediary substance that mediates between the hot discharged air and the compression process. By injecting this cooled air into the compression chamber during backflow, the system reduces operating temperature and prevents thermal inefficiencies without requiring complete system redesign.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If backflow ports are optimized for minimal temperature while maximizing efficiency, then thermal performance improves, but manufacturing precision requirements increase

Engineering Contradiction:
Improvethermal efficiencyVSAvoidbackflow slot sizing
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The patent systematically varies backflow port parameters including size, shape, location, and timing to optimize thermal efficiency. By treating these as adjustable parameters rather than fixed dimensions, the system achieves improved thermal performance while maintaining reasonable manufacturing tolerances through iterative optimization rather than requiring extreme precision.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The backflow ports are designed to dynamically open and close during rotor rotation, with timing controlled by rotor position. This dynamic operation allows the system to adapt backflow characteristics to varying operating conditions, improving thermal efficiency across different load ranges without requiring complex adjustable mechanisms that would increase manufacturing difficulty.

Inventive Principle:
Principle #15Dynamics

3Power

If high pressure ratio is achieved through cooled backflow, then engine power output increases, but system complexity increases due to intercooler integration

Engineering Contradiction:
Improveengine power outputVSAvoidsystem complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The intercooler is designed to perform multiple functions simultaneously: cooling the supercharger discharge, providing cooled air for backflow injection, and potentially serving as a mounting structure for the supercharger assembly. This multi-functionality increases engine power output through improved charging efficiency while minimizing the increase in overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system performs preliminary cooling of the air charge in the intercooler before the air enters the supercharger compression chamber via backflow. This preliminary action reduces the thermal load on the compression process, enabling higher pressure ratios and power output without proportionally increasing system complexity, as the cooling is prepared in advance rather than requiring complex active cooling during compression.

Inventive Principle:
Principle #10Preliminary action

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 system achieves a higher pressure ratio and lower outlet temperature, enhancing engine performance by reducing thermal stress on components and improving boost pressure without exceeding thermal limits, thus increasing horsepower and torque while maintaining operational reliability.

Implementation Method 1

using relatively colder high pressure gas available after the intercooler

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

the high pressure gas from the outlet backflows into the supercharger to compress the low pressure gas into higher pressure gas

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

This also heats up the compressed low pressure gas to a higher temperature based on thermodynamic principles

Methodology Applied
Scientific EffectCompression heating: Adiabatic Heating

Data Source

PatentEP3068990B1Supercharger with modulated backflow event
Publication Date: 2020.01.08 EATON INTELLIGENT POWER LTD
  • EP3068990B1 patent drawingFigure 1A
  • EP3068990B1 patent drawingFigure 1B
  • EP3068990B1 patent drawingFigure 1C

AI summary

An axial inlet, radial outlet supercharger comprises a tubular housing comprising an inlet plane (IP) perpendicular to an outlet plane (OP). Rotor mounting recesses (1030, 1020) are in an inner surface of an inlet wall (1063) parallel to the inlet plane. A triangular outlet (104) is in the outlet plane. An inlet (101) is in the inlet plane. At least two axial flow backflow ports (1222) are in the inlet plane (IP). Alternatively, the supercharger comprises an inlet axis (IA). Each lobed rotor comprises a rotation axis parallel to the inlet axis (IA), wherein the lobes sequentially mesh along the inlet axis (IA) when the rotors rotate, wherein respective lobes are twisted along the length of their respective rotor, and wherein the lobes are timed to fluidly seal the inlet from the outlet. At least two backflow ports (122, 1222) are in the tubular housing.