Indoor Fan Pressure Control Without Static-Pressure Sensors
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Solution Overview
Problem
Conventional air-conditioning apparatuses require complex system design and higher costs due to the need for interconnected control of fan control, damper control, and static-pressure detection, limiting their ability to perform independent control operations.
Innovation Solution
An air-conditioning apparatus that calculates external static pressure and airflow without using a static-pressure detector, controlling the indoor-unit-side fan based on pre-stored values and rotation speed to simplify design and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a static-pressure detector is installed in the duct to detect external static pressure, then the accuracy of static pressure measurement is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the static pressure detection function from a dedicated static-pressure detector and relocates it to the control unit. The control unit calculates external static pressure using the relationship between fan rotation speed and pressure characteristics that were pre-stored during system design, eliminating the need for a separate detection device
Solution Approach 2:
The control unit performs self-detection by utilizing its existing sensing capabilities to measure fan rotation speed and calculating static pressure from this data through pre-stored characteristic relationships, making the system self-sufficient without requiring additional specialized detection equipment
Solution Approach 3:
The patent replaces the mechanical/static-pressure detector-based measurement system with a calculation-based system that uses fan rotation speed data and pre-stored pressure characteristics to derive external static pressure values through computational methods
2Reliability
If interconnected control of damper control, static-pressure detector control, and air-conditioning apparatus control is implemented, then the overall system performance is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the static pressure detection function, fan control function, and air-conditioning apparatus control function into a single integrated control unit. This unified control structure manages all functions through one centralized system rather than requiring separate interconnected control systems for each function
Solution Approach 2:
The control unit is designed with multi-functionality, serving as both the fan controller, the static pressure monitoring system (through calculation), and the air-conditioning apparatus controller. This universal control approach eliminates the need for multiple specialized control systems
Data Source
AI summary
Provided is an easy-to-design, inexpensive air-conditioning apparatus in which an external static pressure and an airflow are calculated without using a static-pressure detector and an indoor-unit-side fan is controlled using those values. An air-conditioning apparatus according to the present invention is configured such that a control unit (indoor-unit-side control unit) stores an external static pressure of an indoor unit calculated from a rotation speed of an indoor-unit-side fan when the airflow of the indoor-unit-side fan is controlled to a predetermined rated airflow and controls the rotation of the indoor-unit-side fan so that the external static pressure of the indoor unit obtained thereafter from the rotation speed of the indoor-unit-side fan approaches the stored external static pressure.