Auxiliary Cabin Heating Circuit for Engine-Off Work Machines

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Solution Overview

Problem

Conventional HVAC systems for work machines are ineffective when the engine is inactive, and they have a long response time during cold start conditions, failing to provide adequate heating in extreme cold weather.

Innovation Solution

A supplementary heating system using an auxiliary heat source powered by an alternate energy form, such as electricity, which is independent of the main engine energy. This system includes an auxiliary fluid circuit that couples the auxiliary heat source with heat exchangers to provide supplementary heat energy into the cabin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the main heating system relies on engine coolant, then heating is provided during engine operation, but heating is ineffective when the engine is inactive

Engineering Contradiction:

Improveheating availabilityVSAvoidoperation mode compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The heating system is divided into two independent segments: a main heating system using engine coolant and an auxiliary heating system using an independent heat source. This segmentation allows each system to operate independently based on engine status, ensuring heating availability whether the engine is running or inactive.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An auxiliary heat source acts as an intermediary heating mechanism that activates when the main engine coolant-based system is unavailable. This intermediary system bridges the heating gap during engine inactivity, maintaining cabin temperature control across all operational states.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the HVAC system waits for coolant to reach operating temperature, then the main heating system can function, but the response time for warming up the cabin is long

Engineering Contradiction:

Improveheating effectivenessVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The auxiliary heating system performs preliminary heating action immediately when heating is required, without waiting for the engine coolant to reach operating temperature. This preliminary action significantly reduces the time delay in providing cabin heating during cold start conditions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The auxiliary heating system uses a compact, independently-powered heat source that can be activated immediately for short-duration heating needs during cold starts, providing quick response without requiring the longer warm-up period of the main coolant system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If the engine is deactivated to reduce emissions and fuel consumption, then environmental performance improves, but the main heating system becomes ineffective

Engineering Contradiction:

ImproveemissionsVSAvoidheating function

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The heating function is segmented into engine-dependent main heating and engine-independent auxiliary heating. This allows the engine to be deactivated for emission reduction while the auxiliary heating segment continues to provide necessary cabin heating.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary heating system is self-sufficient with its own power source and heat generation mechanism, allowing it to operate independently of the engine. This self-service capability enables emission reduction through engine shutdown while maintaining heating reliability through the autonomous auxiliary system.

Inventive Principle:

Principle #25Self-service

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 supplementary heating system ensures continuous heating of the cabin even when the main heating system is inactive, significantly reducing the response time during cold starts and maintaining operator comfort in extreme cold conditions.

Implementation Method 1

an auxiliary heat source powered by an auxiliary energy form alternate to the main energy form. The auxiliary heat source is configured to impart heat to an auxiliary coolant stream

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the auxiliary coolant stream dissipates heat to an air flowing across the one or more heat exchangers and into the cabin

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

providing an auxiliary fluid circuit to fluidly couple the auxiliary heat source with one or more heat exchangers

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS20250074150A1Method and system for heating cabins of work machines

Publication Date: 2025.03.06 CATERPILLAR INC

AI summary

A method, for providing supplementary heat energy into a cabin of a work machine when a main heating system of the cabin is inactive, includes using an auxiliary heat source to impart heat to an auxiliary coolant stream. The main energy form powers a main heat source of the main heating system. Further, the method includes providing an auxiliary fluid circuit to fluidly couple the auxiliary heat source with one or more heat exchangers to supply the auxiliary coolant stream from the auxiliary heat source to the one or more heat exchangers for circulation therewithin. During the circulation of the auxiliary coolant stream within the one or more heat exchangers, the auxiliary coolant stream dissipates heat to an air flowing across the one or more heat exchangers and into the cabin to provide the supplementary heat energy into the cabin.