Vehicle Evaporator Core Control for Icing-Free A/C Cooling
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Solution Overview
Problem
HVAC systems typically use a single set of compressor on and off setpoints to prevent evaporator core icing, which compromises AC performance in situations where a lower setpoint could be used without icing, due to the temperature sensor not always detecting the coldest location of the evaporator core.
Innovation Solution
Implementing an HVAC control strategy that uses an icing heuristic to adjust compressor setpoints based on additional factors such as outside air temperature, HVAC mode, blower speed, and airflow distribution, allowing for optimized compressor on and off setpoints to prevent icing while maintaining AC performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single set of compressor setpoints is used to prevent evaporator core icing, then the evaporator core is protected from freezing, but A/C performance is compromised in situations where a lower setpoint could be used
Solution Approach 1:
The patent implements multiple sets of compressor on and off setpoints that are dynamically selected based on outside air temperature conditions. The climate controller device switches between different setpoint configurations (first set for lower temperatures, second set for higher temperatures) to optimize both evaporator protection and cooling performance according to environmental conditions.
Solution Approach 2:
The patent changes the setpoint parameter values based on outside air temperature thresholds. When the outside air temperature is below a threshold, a first set of setpoints is used with higher temperature margins to prevent icing. When the outside air temperature is above the threshold, a second set of setpoints is used with lower temperature margins to maximize cooling performance.
2Reliability
If a higher compressor off setpoint is used to reduce evaporator core freezing risk, then evaporator core protection is improved, but cooling performance deteriorates
Solution Approach 1:
The patent adjusts the compressor off setpoint parameter based on outside air temperature conditions. For lower outside air temperatures, a higher off setpoint is used to maintain evaporator temperature above freezing. For higher outside air temperatures, a lower off setpoint is used to allow the evaporator to reach lower temperatures for improved cooling efficiency.
Solution Approach 2:
The system dynamically adjusts the compressor off setpoint based on real-time outside air temperature measurements. The climate controller selects between different setpoint configurations to optimize the balance between evaporator protection and cooling performance according to current environmental conditions.
3Device complexity
If a single setpoint configuration is used for all conditions, then system complexity is minimized, but adaptability to different environmental conditions deteriorates
Solution Approach 1:
The patent segments the control system into multiple setpoint configurations (first set and second set of compressor on and off setpoints) that are selected based on outside air temperature conditions. This segmentation allows the system to adapt to different environmental conditions while maintaining a relatively simple control structure with a temperature threshold-based selection mechanism.
Data Source
AI summary
A climate controller device may be configured to perform operations including comparing an outside air temperature to a threshold temperature; selecting, based on the comparison, one of a function to determine target compressor off setpoint values for relatively lower temperatures and a function to determine target compressor off setpoint values for relatively higher temperatures; retrieving a value according to the selection function to determine target compressor off setpoint values, the value specifying a compressor off setpoint value corresponding to airflow configuration settings; and determining a target compressor off setpoint value based at least in part on the retrieved value.