Abstract
Keywords - climate control, air conditioning, thermal comfort, sensing, infrared sensor
Customers tend to require more comfortable climate control in passenger compartments. Infrared sensors, which sense object surface temperature with no contact, are expected to improve thermal comfort. Next three kinds of application are considered for the infrared sensors when they are used for the climate control.
A. Sensing thermal load in a passenger compartment
B. Sensing passenger´s clothing surface temperature
C. Sensing passenger´s skin temperature
This paper is concerned with the comparison of the three applications and development of climate control system for the A and B application.
First, correlation of the skin temperature and the clothing surface temperature with thermal comfort and environment around the passenger is discussed. As the result of the discussion, it is indicated that not only the skin temperature but also the clothing surface temperature is useful for the climate control because it is influenced by skin temperature and environment around the passenger.
Next, the single infrared sensor system, which has one thermopile in it, is introduced and methodology of sensing thermal load and control is discussed. In a conventional climate control system that uses a room air temperature sensor, an ambient air temperature sensor and a solar radiation sensor, climate condition is usually controlled according to thermal load. The single infrared sensor senses average surface temperature of a driver and interior around the driver. By adjusting the ratio of surface area of objects in the sensing area, sensed temperature represents thermal load that is influenced by the room air temperature, the ambient air temperature and the solar radiation sensor. Sensing principle, structure and installation of the sensor is introduced, and results of climate control are shown in comparison with the conventional control.
Finally, the matrix infrared sensor system, which has six thermopiles in it, is introduced. The sensor detects six-area surface temperature individually. The sensor consists of a lens, an IC that has six thermopiles, a circuit and a case, and is improved to detect in-cabin surface temperature accurately even under severe environment conditions. Since the sensor can detect passengers´ clothing surface temperature, it is expected to realize more comfortable climate control. The sensor is used with the four-zone control HVAC system that controls outlet air temperature and mode individually for each seat according to detected temperatures. The system estimates passengers' thermal conditions from sensed clothing temperature when a passenger gets in the vehicle from a very hot or cold condition, and actuates the HVAC to adjust climate condition on the seat on the passenger gets into to be either cooler or warmer. This control realizes a pleasant thermal feeling of climate control.