Compound Engine Expander Piston Deactivation

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Solution Overview

Problem

Traditional secondary expander piston engine designs are not beneficial under low load conditions due to parasitic losses outweighing the additional energy extracted, as they are ineffective and counter-productive, especially in automobile engines that operate under varying conditions including substantial low-load operations.

Innovation Solution

A piston compound internal combustion engine with a secondary expander piston that can be deactivated or have its stroke reduced under low load conditions, featuring two mechanizations for coupling with power pistons and crankshaft, and control strategies to optimize engine efficiency by activating or deactivating the expander piston based on engine load and temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a secondary expander piston is employed to extract additional energy from exhaust gases, then fuel efficiency is improved under high load conditions, but parasitic losses increase under low load conditions

Engineering Contradiction:

Improvefuel efficiencyVSAvoidparasitic losses

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The expander piston is made dynamically controllable through a deactivation mechanism that allows it to be selectively engaged or disengaged from the crankshaft. Under low load conditions, the expander piston is deactivated to eliminate parasitic losses. Under high load conditions, the expander piston is activated to extract additional energy from exhaust gases, thereby resolving the contradiction between fuel efficiency and parasitic losses across varying operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The operational state of the expander piston is changed as a variable parameter based on engine load conditions. A control system monitors engine operating parameters and adjusts the expander piston's engagement status accordingly, transitioning between active and deactivated states to optimize the balance between energy extraction and parasitic losses

Inventive Principle:

Principle #35Parameter changes

2Power

If the secondary expander piston operates continuously, then energy extraction is maximized, but over-expansion losses occur under low load conditions

Engineering Contradiction:

Improveenergy extractionVSAvoidover-expansion losses

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The expander piston operates periodically rather than continuously, being activated only during high load conditions when energy extraction is beneficial and deactivated during low load conditions when over-expansion losses occur. This periodic engagement pattern allows the system to maximize energy extraction when needed while avoiding unnecessary losses during low demand periods

Inventive Principle:

Principle #19Periodic 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

This approach reduces parasitic losses and over-expansion, significantly increasing fuel efficiency by eliminating the expander piston's losses during low load operations while maintaining efficiency under medium and high load conditions.

Implementation Method 1

a secondary expander piston to extract additional energy from exhaust gases

Methodology Applied

Scientific EffectExpansion:

Implementation Method 2

extract additional energy from exhaust gases being expelled from the primary power pistons

Methodology Applied

Scientific EffectThermal energy conversion:

Data Source

PatentUS9897000B2Exhaust compound internal combustion engine with controlled expansion

Publication Date: 2018.02.20 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A piston compound internal combustion engine is disclosed with an expander piston deactivation feature. A piston internal combustion engine is compounded with a secondary expander piston, where the expander piston extracts energy from the exhaust gases being expelled from the primary power pistons. The secondary expander piston can be deactivated and immobilized, or its stroke can be reduced, under low load conditions in order to reduce parasitic losses and over-expansion. Two mechanizations are disclosed for the secondary expander piston's coupling with the power pistons and crankshaft. Control strategies for activation and deactivation of the secondary expander piston are also disclosed. In addition, six-cylinder engine configurations are defined by replicating groups of two power pistons and one expander piston.