Variable Speed Blower Control for HVAC Cooling Capacity Adjustment
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Solution Overview
Problem
Conventional HVAC systems face inefficiencies in adjusting cooling capacity with outdoor ambient temperature changes, leading to excess energy consumption due to the need for multiple compressors and complex hardware configurations.
Innovation Solution
Implementing a variable speed blower control system that adjusts fan speed in response to temperature changes, allowing for gradual transitions between fan speeds to match cooling demand, reducing the need to turn off compressors and minimizing excess cooling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple constant speed compressors are used to adjust cooling capacity, then the cooling capacity can be adjusted by turning compressors on or off, but the device complexity and hardware requirements increase
Solution Approach 1:
The patent extracts the cooling capacity adjustment function from the compressor and relocates it to the blower motor. Instead of using multiple compressors to provide different cooling capacities, a single compressor runs continuously while the blower motor speed is varied to match cooling demand with airflow capacity. This eliminates the need for multiple compressors and their associated control hardware.
Solution Approach 2:
The blower motor acts as an intermediary between the single compressor and the cooling demand. By controlling the blower motor speed, the system mediates the mismatch between fixed compressor output and variable cooling requirements, allowing a single compressor to effectively provide multiple cooling capacity levels without requiring multiple compressors.
2Loss of energy
If multiple compressors are used to match cooling demand, then excess cooling capacity can be reduced, but the system costs and physical footprint increase
Solution Approach 1:
The patent applies dynamics by making the blower motor speed variable rather than fixed. The blower motor speed is dynamically adjusted based on cooling demand and outdoor ambient temperature, allowing the system to match cooling capacity to actual needs continuously. This dynamic adjustment eliminates excess cooling capacity without requiring multiple compressors, thereby reducing system cost and physical footprint.
Solution Approach 2:
The system changes the operational parameter of the blower motor from constant speed to variable speed. By adjusting the blower motor RPM, the airflow through the evaporator is controlled, which directly affects the cooling capacity. This parameter change allows a single compressor to effectively provide variable cooling output, reducing the need for expensive multi-compressor configurations.
3Use of energy by moving object
If compressor speed is reduced to match cooling demand, then energy consumption decreases, but compressor performance and reliability may be affected
Solution Approach 1:
The patent extracts the speed variation function from the compressor and assigns it to the blower motor. The compressor operates continuously at full speed, maintaining optimal performance and reliability, while the blower motor speed is reduced to match cooling demand. This extraction of the speed control function protects the compressor from the negative effects of variable speed operation.
Solution Approach 2:
The blower motor serves as an intermediary that absorbs the speed variation requirements. Instead of varying compressor speed, the system varies blower motor speed, allowing the compressor to operate reliably at constant full speed while still achieving energy savings through reduced airflow demand on the cooling system.
4Loss of energy
If fan speed is adjusted to reduce excess cooling capacity, then energy consumption is reduced, but cooling capacity control precision must be maintained
Solution Approach 1:
The system implements feedback control by continuously monitoring outdoor ambient temperature and adjusting blower motor speed accordingly. The controller receives temperature input and adjusts the blower motor RPM to maintain the appropriate differential between evaporator inlet and outlet temperatures, ensuring precise cooling capacity control while minimizing energy consumption.
Solution Approach 2:
The patent replaces mechanical multi-stage compressor systems with an electronically controlled variable speed blower motor system. The electronic control system provides precise adjustment of blower speed, offering finer control resolution than mechanical compressor staging. This substitution enables precise cooling capacity control through electronic modulation of airflow rather than mechanical compression stage switching.
Data Source
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AI summary
A temperature control system that includes a sensor (240), a variable speed blower (224), and a controller (234). The controller is configured to receive an air temperature measurement from the sensor and determine a temperature value based on the received air temperature measurement. The controller is further configured to compare the determined temperature value to a first threshold value and a second threshold value and to operate the variable speed blower based on the comparison. The controller is configured to set the variable speed blower to a first fan speed when the temperature value is below the first threshold value and to a second fan speed when the temperature value is above the second threshold value. The controller is further configured to set the variable speed blower to a third fan speed that linearly correlates with temperature when the temperature value is between the first threshold and the second threshold.