Three Butterfly Door HVAC Airflow Control
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Solution Overview
Problem
Existing vehicle HVAC systems face challenges with air bypass during partial recirculation mode, requiring larger packaging and limited control modes, which affect airflow control and user operation.
Innovation Solution
The implementation of three 'butterfly' doors with associated linkage design allows for multiple modes, including fresh, partial recirculation, and recirculation, while preventing fresh air from bypassing the HVAC system, and includes RAM air control to maintain airflow as vehicle speed increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dual intake system for air from outside and air from inside is used, then fresh mode and recirculation mode are achieved, but the packaging size increases and air bypass occurs during partial recirculation mode
Solution Approach 1:
The patent divides the air intake control into three separate butterfly doors: first door controls exterior air intake, second door controls interior air intake, and third door controls the mixing passage. This segmentation allows independent control of each air source and passage, enabling precise airflow management while maintaining a compact dual-intake structure that prevents air bypass during partial recirculation mode
Solution Approach 2:
The patent implements dynamic control of the three butterfly doors based on operational mode requirements. During partial recirculation mode, the third door dynamically adjusts the mixing passage opening to prevent bypass while allowing controlled mixing. The doors can be independently actuated to transition between fresh mode, recirculation mode, and partial recirculation mode, providing adaptability without increasing packaging size
2Adaptability or versatility
If a dual intake system is used, then fresh mode and recirculation mode are achieved, but the device complexity increases
Solution Approach 1:
The three butterfly doors serve multiple functions: the first door controls exterior air intake for both fresh mode and partial recirculation mode, the second door controls interior air intake for recirculation mode and partial recirculation mode, and the third door controls the mixing passage to enable transitions between modes. This multi-functionality allows a single door system to handle all air intake requirements without requiring separate complex control mechanisms for each mode
Solution Approach 2:
The third butterfly door acts as an intermediary element that controls the mixing passage between exterior and interior air intakes. By positioning and actuating this intermediate door, the system can smoothly transition between fresh mode, partial recirculation mode, and recirculation mode, simplifying the overall control architecture while maintaining versatility
3Reliability
If three butterfly doors are used, then partial recirculation mode with bypass prevention is achieved, but the device complexity increases
Solution Approach 1:
The patent incorporates a control system that monitors the positions of the three butterfly doors and adjusts them based on the desired operational mode. During partial recirculation mode, the control system provides feedback to ensure the third door is properly positioned to prevent bypass while maintaining the desired mix of exterior and interior air. This feedback mechanism ensures reliable bypass prevention without requiring overly complex mechanical linkage systems
Data Source
AI summary
A heating, ventilation and air conditioning system includes a blower unit that has an interior air intake and an exterior air intake. Three doors are moved between open and closed positions to define a recirculation mode, a fresh mode and a partial recirculation mode. As the doors move between their open and closed positions, a variable partial mode and a variable fresh mode are defined.