Air conditioner indoor unit and air conditioner indoor system

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Solution Overview

Problem

The main board in existing air-conditioning apparatus indoor units becomes larger due to the need for multiple connection terminals to accommodate additional functions and expansion units, particularly when a microcomputer is used for controlling these units.

Innovation Solution

An indoor unit with a main board connected to expansion units via an expansion board, which includes terminals compatible with the main board's standards, allowing for centralized control without the need for additional terminals on the main board.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple connection terminals are added to the main board to accommodate additional functions and expansion units, then the control capability and adaptability are improved, but the main board size increases

Engineering Contradiction:
Improvecontrol capabilityVSAvoidmain board size
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent divides the control system into a main board and separate drive boards. Each drive board handles specific additional functions (humidification, ionization, air blowing), while the main board maintains a compact size with minimal terminals. This segmentation allows functional expansion without increasing main board size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces drive boards as intermediary components between the main board and expansion units. The drive boards receive control signals from the main board and directly control the expansion units, eliminating the need for multiple direct connection terminals on the main board.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the main board is made larger to include multiple connection terminals, then more expansion units can be connected, but the air passage and installation flexibility are reduced

Engineering Contradiction:
Improvenumber of expansion unitsVSAvoidair passage
Core Design Contradiction:
Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

By segmenting the control architecture into main board + drive boards, the patent enables connection to multiple expansion units through distributed terminals on drive boards rather than requiring a larger main board, thus preserving air passage dimensions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent shifts the terminal distribution from a two-dimensional expansion on the main board to a hierarchical structure where drive boards provide additional connection dimensions, allowing multiple expansion units to connect without increasing main board footprint.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3757474B1Air conditioner indoor unit and air conditioner indoor system
Publication Date: 2026.02.11 MITSUBISHI ELECTRIC CORP
  • EP3757474B1 patent drawingFigure 1
  • EP3757474B1 patent drawingFigure 2~3
  • EP3757474B1 patent drawingFigure 4~5

AI summary

An indoor unit of an air-conditioning apparatus includes a main body including a main board that is provided with a control terminal compatible with a plurality of expansion units. The main board is connected to an expansion board provided with at least one expansion terminal that is a connection terminal compliant with the same standard as the control terminal, and is connected to at least one of the plurality of expansion units via the expansion board.