Engine Air Shutoff Valve Fail-Safe Control

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Solution Overview

Problem

Internal combustion engines often run uncontrollably and risk damage when operating outside their designed speed range, especially in explosive atmospheres, where manual shutdown is error-prone and delayed, posing risks of engine damage and potential explosions.

Innovation Solution

An engine system with a movable air shutoff valve controlled by an actuator and sensor system that automatically detects and responds to overspeed conditions, deactivating the valve to block airflow and simultaneously reducing fuel injection, thereby terminating engine operation quickly and reducing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual shutdown is used to stop a runaway engine, then the engine can be shut down, but operator delay and errors cause increased damage and reduced reliability

Engineering Contradiction:

Improveshutdown reliabilityVSAvoidshutdown time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system enables automatic shutdown through self-monitoring sensors that detect runaway conditions and self-actuating mechanisms that close the air intake valve without human intervention, eliminating operator delay and errors

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Sensors continuously monitor engine operating parameters and provide feedback to the control system, which automatically activates the shutdown sequence when runaway conditions are detected, creating a closed-loop protective system

Inventive Principle:

Principle #23Feedback

2Extent of automation

If electrical or hydraulic systems are used to control the air shutoff valve, then automated shutdown is achieved, but system failures can prevent reliable shutdown

Engineering Contradiction:

Improveshutdown automationVSAvoidshutdown reliability

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

A mechanical spring is pre-loaded to provide fail-safe closing force on the air intake valve, ensuring shutdown occurs even if electrical or hydraulic systems fail, cushioning against automation vulnerabilities

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The system replaces purely mechanical control with an integrated electro-mechanical system where electrical/hydraulic actuators work alongside a mechanical spring, combining automation benefits with mechanical reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If the air shutoff valve is designed to close automatically during runaway, then shutdown speed increases, but the valve may not open reliably for normal operation

Engineering Contradiction:

Improveshutdown speedVSAvoidvalve operation reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A mechanical spring provides counterbalancing force that can be overcome by the actuator during normal operation but automatically engages during runaway conditions, enabling both reliable opening and rapid closing

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The valve system transitions from static positioning to dynamic response, where the spring-actuator combination adapts to different operating conditions, providing controlled opening during normal operation and rapid closing during shutdown

Inventive Principle:

Principle #15Dynamics

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 effectively and reliably terminates engine operation during overspeed conditions, preventing damage and reducing the risk of explosions in explosive atmospheres by automatically shutting down the engine, even in the event of electrical or hydraulic failures.

Implementation Method 1

a biasing element configured to move the valve from the first position toward the second position when the actuator is deactivated

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a sensor configured to sense an operating condition of the engine and generate a signal indicative of the operating condition

Methodology Applied

Scientific EffectSensor detection:

Implementation Method 3

an actuator selectively activated to move the valve from the second position toward the first position

Methodology Applied

Scientific EffectActuator actuation:

Data Source

PatentUS8662055B2Engine system having failure-protected air shutoff control

Publication Date: 2014.03.04 CATERPILLAR INC

AI summary

An engine system is disclosed. The engine system may have an engine, an intake duct, and a valve disposed within the intake duct and movable between a flow-passing first position, and a flow-blocking second position. The engine system may also have an actuator configured to move the valve from the second position toward the first position, and a biasing element configured to move the valve from the first position toward the second position. The engine system may additionally have a sensor configured to sense an operating condition of the engine, and a controller. The controller may be configured to receive an input indicative engine activation, and to activate the actuator based on the input. The controller may also be configured to make a determination that the operating condition of the engine has deviated from a desired operating condition, and to deactivate the actuator based on the determination.