Vehicle HVAC Startup Control for Cabin Cooling
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Solution Overview
Problem
Vehicle HVAC systems in hot climates face challenges in quickly cooling the cabin upon startup, leading to discomfort due to the introduction of heated air, as the air conditioning system takes time to reach a smoothly running condition and heated air is circulated within the duct system.
Innovation Solution
A climate control system that determines specific conditions before startup, such as HVAC evaporator core temperature and ambient temperature, to automatically adjust blower speed and airflow distribution, reducing heated air introduction into the cabin, and later increasing airflow once conditions are met for efficient cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the HVAC blower engages at high speed to quickly cool the cabin, then the cooling response time is reduced, but heated air from the duct system is circulated into the passenger cabin causing discomfort
Solution Approach 1:
The system performs preliminary cooling by directing airflow away from the passenger cabin (to the defrost mode) before the AC system is fully operational and capable of providing cooled air. This preliminary action removes heated air from the duct system without introducing it into the cabin, preparing the system for effective cooling once conditions are met.
Solution Approach 2:
The HVAC system dynamically adjusts the blower speed and airflow distribution mode based on real-time monitoring of AC system conditions. The controller transitions the system between different operating states (reduced speed with defrost mode, increased speed with normal mode) as the AC system reaches operational thresholds, optimizing performance at each stage.
2Object-affected harmful factors
If the HVAC system waits for the AC compressor to reach smooth operation before engaging, then heated air circulation is avoided, but the perceived response time for cabin cooling increases
Solution Approach 1:
The system initiates preliminary cooling actions immediately upon startup by engaging the blower in defrost mode, which cools the duct system and removes heated air without circulating it into the cabin. This preliminary action reduces the overall cooling time once the AC system becomes fully operational.
Solution Approach 2:
The HVAC system maintains continuous useful action by keeping the blower operating throughout the startup sequence, first in defrost mode for preliminary cooling and then transitioning to normal mode for full cabin cooling. This continuous operation eliminates idle time and maintains perceived system responsiveness.
3Productivity
If the HVAC blower operates at high speed from startup, then quick cooling is achieved, but passenger discomfort occurs due to hot air discharge
Solution Approach 1:
The cooling process is segmented into distinct phases: a preliminary phase where the blower operates at high speed in defrost mode to cool the duct system, followed by a transition phase where the system switches to normal airflow mode once the AC system reaches operational temperature thresholds. This segmentation allows high-speed operation without direct cabin exposure to heated air.
Solution Approach 2:
The defrost mode serves as an intermediary state that allows the blower to operate at high speed without introducing heated air into the cabin. By directing airflow through the defrost pathway instead of the cabin pathway, the system mediates between the need for high-speed operation and the need to avoid passenger discomfort.
Data Source
AI summary
A method for controlling a vehicle climate control system includes steps of determining that a first predetermined set of conditions are satisfied whereby a heating, ventilation, and air-conditioning (HVAC) system airflow into a passenger cabin will exceed a predetermined HVAC airflow temperature threshold and, if so, automatically implementing a first climate control system operating condition at least reducing the HVAC airflow into the passenger cabin. On determining that a second predetermined set of conditions are satisfied whereby the HVAC airflow into the passenger cabin will satisfy the predetermined HVAC airflow temperature threshold, the method includes a step of automatically implementing a second climate control system operating condition increasing the HVAC airflow into the passenger cabin. Climate control systems for implementing the described methods are provided.