Underfloor CO2 Refrigerant Circuit for Vehicle Air Conditioning
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Solution Overview
Problem
Vehicle air-conditioning devices using carbon dioxide refrigerant face issues with refrigerant leakage causing increased carbon dioxide concentration, leading to user discomfort and a high center of gravity due to thicker pipes, which affects vehicle stability at high speeds.
Innovation Solution
A vehicle air-conditioning device with a refrigerant circuit installed under the floor, utilizing carbon dioxide as the refrigerant, and featuring separate chambers for indoor and outdoor air handling, with ventilation systems to manage air supply and discharge, ensuring the refrigerant stays under the floor and does not mix with vehicle air, thus maintaining low carbon dioxide concentration and reducing the vehicle's center of gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If carbon dioxide refrigerant is used, then global warming potential is reduced, but refrigerant leakage increases carbon dioxide concentration in the vehicle causing user discomfort
Solution Approach 1:
The air handling system is divided into separate chambers: a first chamber for processing vehicle interior air and a second chamber for processing outdoor air. This segmentation prevents mixed air flow paths and allows independent control of air streams, ensuring that leaked refrigerant in one chamber does not contaminate the vehicle interior air in the other chamber.
Solution Approach 2:
Outdoor air is introduced as an intermediary substance into the second chamber to dilute and replace any carbon dioxide that may leak into the system. The outdoor air-sending device actively supplies fresh outdoor air to the second chamber, creating a buffer that prevents accumulated carbon dioxide from entering the vehicle interior.
2Object-affected harmful factors
If carbon dioxide refrigerant is used, then low global warming potential is achieved, but pipe thickness must be increased to handle high operating pressure
Solution Approach 1:
The refrigerant circuit is relocated from the vehicle interior space to the underfloor area. This spatial repositioning allows the use of thicker, heavier pipes without increasing the overall vehicle height or affecting the interior headroom. The refrigerant circuit operates in a separate dimensional space (underfloor) where weight and thickness constraints are different.
3Strength
If pipe thickness is increased to handle high pressure, then pressure resistance is improved, but vehicle center of gravity rises affecting stability
Solution Approach 1:
The refrigerant circuit components and thick-walled pipes are positioned in the underfloor area, which is below the vehicle's main body. This vertical repositioning lowers the center of gravity of the air-conditioning device, thereby improving vehicle stability during high-speed operation and curve negotiation, while still providing the necessary pressure resistance through increased pipe thickness.
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
The solution effectively suppresses carbon dioxide concentration increases and stabilizes the vehicle's center of gravity, enhancing user comfort and stability, especially during high-speed turns.
Implementation Method 1
a refrigerant circuit having a compressor 1, an outdoor heat exchanger 2, an expansion device 3, and an indoor heat exchanger 4 that are connected by refrigerant pipes to form a refrigeration cycle
Implementation Method 2
an outdoor heat exchanger 2, an expansion device 3, and an indoor heat exchanger 4
Implementation Method 3
a supply ventilation air-sending device that sends air from the outside of the vehicle to the first chamber through the first opening 52, the air supply duct, and the second opening 50
Implementation Method 4
an exhaust ventilation air-sending device that discharges the air in the first chamber to the outside of the vehicle through the third opening 51, the exhaust duct, and the fourth opening 53
Data Source
Figure 1(a)~2(b)
Figure 3(a)~4(b)
Figure 5~6
AI summary
In vehicle air-conditioning devices (100) to (105) including a refrigerant circuit having a compressor (1), an outdoor heat exchanger (2), an expansion device (3), and an indoor heat exchanger (4) that are connected by refrigerant pipes to form a refrigeration cycle; an indoor air-sending device (5) that supplies air to the indoor heat exchanger (4); and an outdoor air-sending device (8) that supplies air to the outdoor heat exchanger (2), the refrigerant circuit is installed under the floor of a vehicle (200) and uses carbon dioxide as the refrigerant.