Vehicle Air-Conditioning Free Cooling Controller Occupancy

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Solution Overview

Problem

Existing vehicle air-conditioning systems face challenges in determining when to perform free cooling, as they do not adequately consider the vehicle occupancy rate, leading to potential discomfort and inefficiencies in energy usage.

Innovation Solution

A vehicle air-conditioning apparatus with a refrigeration cycle device, outdoor air damper, temperature measurers, and a controller that assesses the feasibility of free cooling by comparing a free cooling performance value and an indoor heat load value, taking into account the vehicle occupancy rate to determine if free cooling should be initiated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If free cooling is performed based only on temperature threshold comparison, then energy savings are achieved, but passenger comfort may be degraded when outdoor air temperature does not correspond to vehicle occupancy rate

Engineering Contradiction:

Improveenergy consumptionVSAvoidpassenger comfort

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the decision parameters for free cooling from simple temperature threshold comparison to a comprehensive evaluation including outdoor air temperature, indoor temperature, vehicle occupancy rate, and thermal load characteristics. This multi-parameter approach allows the system to adapt free cooling operation to actual passenger comfort needs while maintaining energy efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by continuously monitoring indoor temperature, outdoor temperature, and occupancy rate, then using this information to dynamically adjust free cooling operation. The system compares the thermal load from passengers against the cooling capacity available from outdoor air, creating a closed-loop control that maintains passenger comfort while optimizing energy consumption.

Inventive Principle:

Principle #23Feedback

2Temperature

If outdoor air intake fan operates during free cooling, then outdoor air is taken into passenger compartment, but electric power is consumed reducing energy savings

Engineering Contradiction:

Improveindoor temperature controlVSAvoidelectric power consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by operating the outdoor air intake fan at reduced capacity or intermittently during free cooling operation, rather than at full capacity continuously. The system provides sufficient outdoor air intake to achieve the required cooling effect while minimizing fan power consumption, accepting that slightly more cooling capacity than theoretically minimum is available to ensure comfort.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent makes the fan operation dynamic by adjusting fan speed and operation timing based on real-time conditions including the temperature difference between outdoor and indoor air, occupancy rate, and required cooling load. The fan operates at variable speeds rather than fixed high speed, optimizing the balance between cooling effectiveness and energy consumption.

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

This approach reduces the likelihood of discomfort in the passenger compartment by ensuring that free cooling is only performed when necessary and achieves further energy savings by optimizing the operation of the air-conditioning system.

Implementation Method 1

a refrigeration cycle device attached to a vehicle and including a compressor, the refrigeration cycle device being configured to form, with the compressor, refrigeration cycle for air cooling of a passenger compartment of the vehicle

Methodology Applied

Scientific EffectRefrigeration cycle:

Implementation Method 2

even during a free cooling operation, there is a need to run an outdoor air intake fan that forms an air flow taking the outdoor air into the passenger compartment

Methodology Applied

Scientific EffectForced convection: Forced Convection

Implementation Method 3

an outdoor heat exchanger (14) as a condenser that condenses the compressed refrigerant

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS11299011B2Vehicular air-conditioning apparatus and air-conditioning method of vehicular air-conditioning apparatus

Publication Date: 2022.04.12 MITSUBISHI ELECTRIC CORP

AI summary

A controller performs a prior determination by determining whether air cooling of a passenger compartment by free cooling control is possible based on a target value of a temperature in the passenger compartment that is set in advance, an outdoor air temperature, and an indoor temperature. The controller also performs a free cooling execution determination by determining whether to perform the free cooling control by comparing (i) a free cooling performance value that depends on a temperature difference between the outdoor air temperature and the indoor temperature and indicates a capacity of air cooling by the free cooling control, and (ii) an indoor heat load value that depends on a vehicle occupancy rate of passengers in the passenger compartment and indicates a difficulty of a temperature decrease in the passenger compartment.