Reciprocating Engine Liquid Air Injection for Balance and Cooling

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Reciprocating internal combustion engines face inefficiencies in power stroke management, particularly in achieving a balanced thermodynamic cycle and preventing fuel freezing, due to the limitations of traditional fuel injection methods.

Innovation Solution

The method involves controlling the injection of liquid air without fuel during a first power stroke and fuel injection during a subsequent power stroke, with the liquid air being injected at a specific time when the piston is closer to one end of the cylinder, and fuel being injected at another time to perform additional power strokes, allowing for variable compression ratios and preventing fuel freezing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If liquid air is injected into the cylinder without fuel during a power stroke, then the piston can perform additional power strokes and engine balance is improved, but the device complexity increases due to precise injection timing control requirements

Engineering Contradiction:
Improveengine balanceVSAvoidinjection timing control
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The engine cycle is segmented into distinct phases with different injection strategies: liquid air injection for power generation without fuel, and fuel injection for subsequent power strokes. This segmentation allows independent optimization of each injection event, improving engine balance while managing control complexity through phased operation rather than simultaneous multi-parameter control

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Liquid air is injected into the cylinder before fuel injection, preparing the combustion chamber with a high-oxygen medium that enables subsequent fuel combustion. This preliminary action of introducing liquid air first creates favorable conditions for the second injection event, allowing the engine to achieve balanced power delivery across multiple stroke types without requiring complex real-time coordination

Inventive Principle:
Principle #10Preliminary action

2Productivity

If fuel is injected at specific times when the piston is closer to one end of the cylinder, then power stroke efficiency is improved, but the manufacturing precision requirements increase for injection timing

Engineering Contradiction:
Improvepower stroke efficiencyVSAvoidinjection timing
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The injection timing is made dynamic rather than fixed, with injection events scheduled based on piston position relative to cylinder ends. The system adapts injection timing to the dynamic state of the piston cycle, injecting liquid air and fuel at optimal moments when the piston is closer to specific ends. This dynamic timing strategy improves power stroke efficiency while reducing the stringency of manufacturing precision requirements compared to fixed high-precision timing

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The injection timing parameter is changed based on piston position throughout the cycle. By varying the timing of liquid air and fuel injection according to piston location (closer to one end vs. the other), the system optimizes combustion efficiency for each injection event. This parameter adaptation allows efficient power extraction without requiring extremely tight manufacturing tolerances on fixed timing mechanisms

Inventive Principle:
Principle #35Parameter changes

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 approach enhances engine balance, reduces vibrations, allows for the use of various fuels by varying the liquid air quantity, and lowers component temperatures, thereby increasing engine life and performance.

Implementation Method 1

controlling injection of a quantity of liquid air, without fuel, into a first end of the cavity at a first time when the piston is closer to the first end than the second end to cause the piston to perform a first power stroke

Methodology Applied
Scientific EffectExpansion: Phase Change

Implementation Method 2

controlling injection of fuel into the first end of the cavity at a second time when the piston is closer to the first end than the second end to cause the piston to perform a second power stroke

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3477087B1Apparatus and methods for controlling reciprocating internal combustion engines
Publication Date: 2020.07.22 ROLLS ROYCE PLC
  • EP3477087B1 patent drawingFigure 1
  • EP3477087B1 patent drawingFigure 2
  • EP3477087B1 patent drawingFigure 3

AI summary

A method of controlling a reciprocating internal combustion engine comprising: a cylinder defining a cavity having a first end and a second end; and a piston moveable within the cavity of the cylinder between the first end and the second end, the method comprising: controlling injection of a quantity of liquid air, without fuel, into the first end of the cavity at a first time when the piston is closer to the first end than the second end to cause the piston to perform a first power stroke; and controlling injection of fuel into the first end of the cavity at a second time when the piston is closer to the first end than the second end to cause the piston to perform a second power stroke.