Air Conditioner Cycle-Rate Feedback for Evaporator Freeze Control
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Solution Overview
Problem
Existing air conditioning systems for vehicles face challenges in maintaining a stable refrigeration cycle rate, leading to large outlet temperature fluctuations and potential durability issues due to rapid or slow cycling, which can result in freezing and inefficiencies.
Innovation Solution
A method that monitors the time between sequential 'on' and 'off' events of the compressor and adjusts the refrigeration 'on' temperature threshold accordingly, either increasing or decreasing it based on predetermined times to match a desired cycle rate, thereby reducing temperature variations and optimizing evaporator regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigeration cycle is stopped and restarted frequently to regulate evaporator temperature, then the evaporator temperature is controlled to prevent freezing, but the outlet temperature fluctuations increase and system durability decreases
Solution Approach 1:
The system monitors the time between sequential refrigeration on/off events and uses this feedback to dynamically adjust the refrigeration on temperature threshold. When the cycle rate is too high (time below predetermined threshold), the on temperature threshold is increased to reduce cycling frequency. When the cycle rate is too low (time above predetermined threshold), the on temperature threshold is decreased to increase cycling frequency. This closed-loop feedback mechanism stabilizes the refrigeration cycle rate and reduces outlet temperature fluctuations while maintaining evaporator temperature control.
Solution Approach 2:
The invention changes the temperature threshold parameter dynamically based on the observed refrigeration cycle rate. Instead of using a fixed temperature threshold, the system adjusts the on temperature threshold upward or downward depending on whether the cycle rate is too high or too low. This parameter adaptation allows the system to maintain reliable operation by preventing both excessive cycling and insufficient cooling, thereby improving system durability while controlling evaporator temperature.
2Productivity
If the refrigeration cycle rate is increased to improve cooling response, then the evaporator cooling efficiency improves, but the outlet temperature variations increase and mechanical component durability decreases
Solution Approach 1:
The system continuously monitors the time between sequential refrigeration events and uses this information to adjust the on temperature threshold. When rapid cycling is detected (indicating high productivity but potential durability issues), the feedback mechanism increases the on temperature threshold to reduce cycling frequency. This maintains adequate cooling response while protecting mechanical components from excessive wear.
Solution Approach 2:
The invention makes the refrigeration control system dynamic by continuously adapting the on temperature threshold based on real-time cycle rate observations. The system transitions from static threshold control to dynamic threshold adjustment, allowing it to optimize between cooling response speed and component durability under varying operating conditions.
3Reliability
If the refrigeration on temperature threshold is increased to reduce cycling frequency, then the system durability improves, but the evaporator temperature control precision decreases
Solution Approach 1:
The system dynamically adjusts the on temperature threshold parameter based on the observed refrigeration cycle rate. When durability is at risk due to excessive cycling, the threshold is increased to reduce frequency. When cooling response is insufficient, the threshold is decreased to improve responsiveness. This dynamic parameter adjustment maintains temperature control precision across varying operating conditions while protecting system durability.
Solution Approach 2:
The invention transforms the static temperature threshold into a dynamic parameter that adapts to system conditions. The on temperature threshold is no longer fixed but varies based on the measured time between refrigeration events, allowing the system to maintain both durability and temperature control precision under different operating scenarios.
4Temperature
If the refrigeration cycle is deactivated early to prevent freezing, then the evaporator temperature is protected, but the outlet temperature fluctuations increase and cooling efficiency decreases
Solution Approach 1:
The system uses feedback from the monitored time between refrigeration events to adjust the on temperature threshold. When early deactivation causes insufficient cooling (low productivity), the feedback mechanism decreases the on temperature threshold to extend cooling duration. When freezing risk is detected, the threshold is increased to activate protection earlier. This feedback-driven adjustment maintains both evaporator temperature protection and cooling efficiency.
Data Source
AI summary
A method for adjusting a natural refrigeration cycle rate of an air conditioner includes monitoring a time between at least two sequential refrigeration “off” events or at least two sequential refrigeration “on” events, and determining whether the time is below or above a predetermined time. If the time is below the predetermined time, the method further includes increasing a refrigeration “on” temperature threshold. If, however, the time is above the predetermined time, the method further includes decreasing the refrigeration “on” temperature threshold.