Variable Ratio Control Knob for HVAC Actuation
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Solution Overview
Problem
Existing control mechanisms for motor vehicle HVAC systems have a fixed transmission ratio between the control knob and connecting rod, limiting the ability to add new operation modes without altering the device, which affects user identification and aesthetics.
Innovation Solution
A control mechanism with a rotating knob and auxiliary transmission gear system, allowing for different transmission ratios by engaging and disengaging toothed portions on the flange, enabling adjustable stroke changes of the cable for various operation modes without modifying the HVAC system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed transmission ratio is used between the control knob and connecting rod, then the mechanical structure is simple, but the ability to add new operation modes is limited
Solution Approach 1:
The transmission mechanism is segmented into multiple gear groups (first gear group with first transmission ratio, second gear group with second transmission ratio, third gear group with third transmission ratio). Each gear group can be independently engaged or disengaged, allowing the system to switch between different transmission ratios. This segmentation enables the addition of new operation modes by engaging different gear groups without fundamentally redesigning the entire transmission mechanism.
Solution Approach 2:
The transmission mechanism transitions from a static fixed ratio to a dynamic variable ratio system. The control knob can rotate within different angular ranges (first, second, and third ranges), and the transmission mechanism dynamically switches between different gear groups based on the rotation range. This dynamic capability allows the same physical knob rotation to produce different cable stroke changes, enabling multiple operation modes including intermediate modes like foot+face mode.
2Ease of operation
If the control knob positions are evenly spaced, then user identification and aesthetics are improved, but the cable stroke changes are not proportional
Solution Approach 1:
The system changes the transmission ratio parameter based on the rotation range of the control knob. When the knob rotates within the first angular range, the first transmission ratio is applied; within the second angular range, the second transmission ratio is applied; and within the third angular range, the third transmission ratio is applied. This parameter change allows evenly spaced knob positions to produce non-uniform cable stroke changes, enabling intermediate operation modes to be positioned evenly while maintaining appropriate stroke proportions for each mode.
3Adaptability or versatility
If the same controlled device is used on many occasions, then economic considerations are satisfied, but the number of operation modes is limited
Solution Approach 1:
The control mechanism is designed with multi-functionality to handle various operation modes using the same controlled HVAC device. By incorporating multiple gear groups with different transmission ratios, the system can support defogging mode, defogging+foot mode, foot mode, face mode, and intermediate modes like foot+face mode all through the same device. This universality allows the controlled device to be used on many occasions with different operation modes without requiring hardware changes, satisfying economic considerations while expanding adaptability.
Data Source
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AI summary
A control mechanism includes a control portion, a transmission portion, and a manipulating portion, in which the control portion comprises a panel and a control piece, with the control piece including a control knob, a rotating shaft, and a knob transmission gear piece; the transmission portion comprises a connecting rod and an auxiliary transmission gear piece, where the connecting rod includes a flange and the flange includes a first side and a second side with a first toothed portion being provided on the first side and a second toothed portion being provided on the second side, and the auxiliary transmission gear piece includes a first pinion and a second pinion; when the control knob rotates within a first rotating range, the knob transmission gear engages with the first toothed portion so as to drive the connecting rod into rotation with a first transmission ratio, when the control knob rotates within a second rotating range, the knob transmission gear disengages with the first toothed portion, and the second pinion engages with the second toothed portion, so that the knob transmission gear drives the connecting rod into rotation with a second transmission ratio via the first pinion and the second pinion; wherein the first transmission ratio differs from the second transmission ratio. A motor vehicle which includes such a control mechanism is also disclosed.