Indoor Fan Speed Limiting for Air Conditioner Heating Control
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Solution Overview
Problem
Air conditioners fail to effectively control the rotational speed of indoor-device fans during heating operations, leading to increased temperatures within the electrical-component box, which can exceed rated temperatures and potentially shorten the service life of electrical components.
Innovation Solution
An air conditioner with a temperature measurement unit that determines an upper limit for the rotational speed of the indoor-device fan based on the temperature of the heat exchanger, controlling the fan to operate at a speed equal to or slower than the determined limit to prevent overheating within the electrical-component box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotational speed of the indoor-device fan is increased to increase air volume and heating capacity, then the heating capacity is improved, but the temperature within the electrical-component box rises due to increased load current and copper loss
Solution Approach 1:
The control unit preliminarily determines the upper limit rotational speed of the fan based on the heat exchanger temperature before operating the fan, thereby preventing the temperature within the electrical-component box from rising excessively in advance
Solution Approach 2:
The control unit measures the temperature of the indoor-device heat exchanger and uses this feedback information to determine the appropriate upper limit rotational speed of the fan, creating a closed-loop control system that balances heating capacity and temperature control
2Temperature
If the rotational speed of the indoor-device fan is reduced to suppress temperature rise within the electrical-component box, then the temperature is controlled, but the air volume and heating capacity are reduced
Solution Approach 1:
The upper limit rotational speed of the fan is dynamically determined based on the measured heat exchanger temperature, allowing the fan speed to be optimized in real-time to balance temperature control and heating capacity requirements
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 solution effectively suppresses the rise in temperature of electrical components within the electrical-component box, preventing overheating and extending the service life of components while maintaining high-capacity and efficient air conditioning by adjusting fan speed based on heat exchanger temperature.
Implementation Method 1
a temperature measurement unit to measure a temperature of the indoor-device heat exchanger
Implementation Method 2
an indoor-device fan to deliver air to the indoor-device heat exchanger
Implementation Method 3
heat is generated due to a load current. That is, when the fan is operated, energy loss in which electric energy is changed to thermal energy by a winding resistance is caused inside a motor that drives the fan. This is so-called copper loss and causes heat generation.
Data Source
AI summary
Included is an indoor device including inside a casing an electrical-component box having electrical components accommodated therein, an indoor-device heat exchanger, and an indoor-device fan to deliver air to the indoor-device heat exchanger. An air conditioner includes a temperature measurement unit to measure a temperature of the indoor-device heat exchanger, and a control unit to determine an upper limit of a rotational speed of the indoor-device fan on the basis of a temperature of the indoor-device heat exchanger measured by the temperature measurement unit, and to execute control to operate the indoor-device fan at a rotational speed equal to or slower than the determined upper limit.