Multi-rotor engine thermal distortion via angular offset

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Solution Overview

Problem

Rotary internal combustion engines, such as Wankel engines, face challenges with unequal thermal expansion due to constant heating and cooling of rotor housings, leading to high local temperatures and thermal distortions, which require complex cooling schemes and can result in dynamic imbalances, particularly problematic in applications like aircraft use.

Innovation Solution

A multi-rotor internal combustion engine design where each rotary unit is axially distributed along a common axis with adjacent units clocked at different angular positions to offset high temperature regions, allowing 'cold' sections to cool 'hot' sections and self-compensate for pressure-induced side loads, thereby simplifying cooling and balancing thermal and dynamic loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If rotary internal combustion engines use constant heating and cooling of rotor housings, then combustion and exhaust phases can occur in dedicated regions, but high local temperatures and unequal thermal expansion occur leading to thermal distortions

Engineering Contradiction:

Improvelocal temperatureVSAvoidthermal expansion uniformity

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The patent applies asymmetry by angularly offsetting adjacent rotary internal combustion units so that hot regions do not align. Specifically, adjacent units are positioned at different angular positions about the engine axis, creating an asymmetric thermal distribution pattern that prevents concentration of heat in any single location, thereby reducing thermal distortions and unequal expansion.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent transitions from a single-plane thermal management approach to a multi-dimensional solution by distributing rotary units along the engine axis and angularly offsetting them. This spatial arrangement in multiple dimensions allows hot regions to be distributed throughout the engine volume rather than concentrated in one area, enabling more effective thermal management.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Temperature

If complex cooling schemes are implemented to cool hot regions, then thermal management improves, but device complexity increases

Engineering Contradiction:

Improvehot region temperatureVSAvoidcooling scheme complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of heat generation into a beneficial thermal management solution. By angularly offsetting adjacent units, the hot regions of one unit are positioned near the cold regions of adjacent units, allowing passive heat transfer from hot to cold areas. This transforms the waste heat problem into a self-regulating thermal balance without requiring complex active cooling systems.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Stability of the object's composition

If rotary units are positioned to offset high temperature regions, then thermal distortions reduce, but manufacturing and assembly complexity increases

Engineering Contradiction:

Improvethermal distortionVSAvoidhousing angular positioning

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent segments the engine into multiple independent rotary units, each capable of being manufactured and assembled separately. The housing is designed with modular sections that can be positioned at different angular orientations. This segmentation allows for standardized manufacturing of individual units followed by precise angular assembly, balancing manufacturing ease with thermal performance.

Inventive Principle:

Principle #1Segmentation

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 design effectively reduces thermal distortions and dynamic imbalances, simplifies cooling requirements, and optimizes engine balance and torque output by angularly offsetting high temperature regions and compensating for pressure side loads, enhancing the engine's performance and reliability, especially in demanding applications like aircraft engines.

Implementation Method 1

allowing 'cold' sections to cool 'hot' sections

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

self-compensate for pressure-induced side loads

Methodology Applied

Scientific EffectPressure balance: Pressure Gradient

Data Source

PatentUS8707929B2Multi-rotor rotary engine architecture

Publication Date: 2014.04.29 PRATT & WHITNEY CANADA CORP

AI summary

A multi-rotor internal combustion engine has a plurality of rotary internal combustion units axially distributed along an engine axis. Each unit has a rotor mounted on an eccentric portion of the shaft inside a housing. The housings of adjacent rotary internal combustion units have different angular positions about the engine axis so as to angularly offset the housing from adjacent housings, which may provide for a more uniform temperature distribution around the housings and may also or instead allow optimising of the balancing of pressure induced side loads on the shaft of the rotors.