HVAC Rear Control Retention via Coolant Temperature Logic
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Solution Overview
Problem
Conventional vehicle HVAC control systems require frequent manual intervention by front occupants to enable rear HVAC control after vehicle restart, leading to inconvenience and discomfort for rear occupants, as the rear manual button is automatically de-actuated upon vehicle shutdown.
Innovation Solution
The system uses the engine coolant temperature to determine if the vehicle has been inoperative for a short or long period, allowing the rear control panel to maintain control if the vehicle was recently used, and requiring manual actuation from the front panel only if it has been inactive for an extended time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rear manual button is automatically de-actuated when the vehicle is turned off, then the rear HVAC system is protected from inadvertent control by the rear control panel, but the rear occupants must wait for manual intervention from the front occupant after vehicle restart
Solution Approach 1:
The system changes the operational parameter of the rear manual button based on the vehicle's operational state. When the vehicle is restarted, the button remains actuated (different from conventional de-actuation) if it was actuated before shutdown, allowing rear control without requiring front occupant intervention. This parameter change resolves the contradiction by maintaining reliability through conditional logic while improving ease of operation for rear occupants.
2Ease of operation
If the rear manual button remains actuated after vehicle restart, then rear occupants can immediately control the rear HVAC system, but front occupants lose the ability to prevent inadvertent rear control when the rear cabin is unoccupied
Solution Approach 1:
The system dynamically adjusts the rear manual button state based on vehicle operational conditions. Upon restart, the button maintains its previous actuated state temporarily, enabling immediate rear control. The system dynamically monitors for front occupant input and allows de-actuation if needed, creating a dynamic balance between ease of operation and prevention of inadvertent control.
3Reliability
If the rear manual button requires actuation after every vehicle restart, then front occupants maintain control authority, but this creates inconvenience and delays for rear occupants needing HVAC control
Solution Approach 1:
The system performs preliminary action by maintaining the rear manual button in an actuated state after vehicle restart, anticipating that rear occupants may need HVAC control. This eliminates the need for immediate front occupant intervention, reducing the time delay for rear HVAC activation while still allowing front occupants to reclaim control if needed by de-actuating the button.
Data Source
AI summary
A vehicle heating, ventilation, and air conditioning system includes front and rear HVAC systems. A controller receives data from front and rear control panels and controls the front and rear HVAC systems. Actuating a rear manual button on the front control panel allows control of the rear HVAC system via the rear control. Engine coolant temperature is used to judge if the vehicle has been inoperative for a long time. If the vehicle has not been inoperative for long, and the rear manual button was actuated prior to the vehicle shut down, rear manual control over the rear HVAC system is enabled. If the vehicle has been inoperative for a long time, or if the rear manual button was not actuated immediately prior to vehicle shut down, rear manual control is not enabled, thereby preventing operation of the rear HVAC system by the rear control panel.