Vehicle HVAC Skin Temperature Offset Control
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Solution Overview
Problem
Existing HVAC systems in transportation vehicles indirectly control occupant comfort by monitoring ambient air temperature, failing to effectively regulate skin temperature, which is a better indicator of comfort, due to the complexity of the thermodynamic environment within the vehicle.
Innovation Solution
A system that includes skin temperature sensors to measure the driver's skin temperature and cabin temperature sensors, with a controller module adjusting the HVAC system by applying an offset to the target cabin temperature based on the difference between the two, using filtered measurements and a tunable gain factor to ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HVAC systems directly regulate skin temperature based on skin temperature sensor feedback, then occupant comfort is improved, but system complexity increases due to the complex thermodynamic environment in vehicle interior
Solution Approach 1:
The patent introduces an intermediary approach by using skin temperature as a feedback signal to adjust the target cabin temperature setpoint, rather than directly controlling skin temperature. The personalization module acts as a mediator that translates skin temperature deviations into offset adjustments for the HVAC target temperature, simplifying the control architecture while still achieving personalized comfort.
Solution Approach 2:
The system changes the target cabin temperature parameter dynamically based on skin temperature feedback. Instead of adding complex direct skin temperature control mechanisms, the invention adjusts the temperature setpoint parameter to account for individual occupant thermal characteristics, thereby improving comfort through parameter adaptation rather than structural complexity.
2Adaptability or versatility
If skin temperature feedback control is implemented without limitations, then personalized comfort is improved, but system stability deteriorates due to excessive adjustments
Solution Approach 1:
The patent applies partial action by implementing limitations on the offset adjustments to target cabin temperature. Rather than allowing unlimited adjustments based on skin temperature feedback, the system constrains the offset within reasonable bounds, preventing excessive HVAC actuator commands while still providing meaningful personalized comfort adjustment.
Solution Approach 2:
The system uses feedback from skin temperature sensors to continuously adjust the target cabin temperature offset. The personalization module monitors skin temperature deviations and dynamically modifies the temperature setpoint, creating a closed-loop feedback system that adapts to individual occupant needs while maintaining overall system stability through the implemented limitations.
3Measurement precision
If multiple skin temperature sensors are placed throughout the vehicle, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies local quality by placing skin temperature sensors at specific strategic locations where they can effectively measure the driver's skin temperature. Rather than distributing sensors throughout the entire vehicle, the system focuses measurement capability on the primary occupant zone, achieving sufficient measurement precision for personalized control without excessive system complexity.
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
This approach provides personalized climate control, enhancing occupant comfort and potentially leading to energy savings by optimizing HVAC operation based on actual skin temperature, while maintaining system stability and preventing excessive adjustments.
Implementation Method 1
skin temperature sensor for measuring an actual skin temperature of the driver
Implementation Method 2
cabin temperature sensor for measuring an actual cabin temperature of ambient air within the passenger cabin
Implementation Method 3
HVAC system provides heated and cooled air flow into the passenger cabin
Implementation Method 4
a blower passes air through heat exchangers and delivers conditioned air to various points within the passenger cabin
Implementation Method 5
The actual cabin temperature is filtered according to a first time constant. A personalization module stores a target skin temperature, wherein the personalization module determines an offset to be applied to the target cabin temperature according to a second error between the target skin temperature and the actual skin temperature. The actual skin temperature is filtered according to a second time constant longer than the first time constant.
Data Source
AI summary
An HVAC system for a vehicle includes infrared skin temperature sensors for measuring actual skin temperatures of the driver and a cabin temperature sensor for measuring an actual cabin temperature of ambient air within the passenger cabin. A controller module stores a target cabin temperature. The controller module controls the HVAC system according to a first error between the target cabin temperature and the actual cabin temperature. A personalization module stores a target skin temperature, and the personalization module determines an offset to be applied to the target cabin temperature according to a second error between the target skin temperature and the actual skin temperature. Infrared temperature measurements are collected for the left and right sides of a person's face, and the actual skin temperature is selected as the one that deviates most from the actual cabin temperature.