Design of an Automatic Control Algorithm for Energy-Efficient ...
Design of an Automatic Control Algorithm for Energy-Efficient ...
Design of an Automatic Control Algorithm for Energy-Efficient ...
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10 Hardware <strong>an</strong>d characteristics <strong>of</strong> the MUTE prototype 103<br />
over the internal control <strong>of</strong> the heater, which is not suited <strong>for</strong> this application. However, a<br />
pro<strong>of</strong>-<strong>of</strong>-concept will be possible with the available components, but a production vehicle<br />
will need a new developed design.<br />
10.4 The sensors<br />
The temperature is measured at five positions. The heater inlet <strong>an</strong>d outlet temperature<br />
is captured in the HVAC-system in order to be able to detect a heater fault. The air<br />
temperature at the outlet to the cabin is needed <strong>for</strong> the heater control <strong>an</strong>d the cold air<br />
prevention system. For fog prediction <strong>an</strong>d prevention, the windscreen temperature is<br />
required. Finally, a combination <strong>of</strong> relative humidity <strong>an</strong>d temperature measurements is<br />
applied to determine the state <strong>of</strong> the cabin <strong>an</strong>d the ambient air. The heater fuel reservoir<br />
fill level is also observed by a sensor.<br />
As temperature tr<strong>an</strong>sducers Analog Devices AD22100 temperature sensors are em-<br />
ployed. They cover a r<strong>an</strong>ge from -50 to +150 ℃ <strong>an</strong>d feature a voltage output that is<br />
linearly proportional to the temperature. Both humidity sensors are <strong>of</strong> the type Honey-<br />
well HIH-4000. They use capacitive sensing <strong>an</strong>d give a near linearly voltage output in<br />
relation to the relative humidity. There is no solar sensor in the MUTE prototype.<br />
Care has to be taken when positioning the sensors. Bad placing c<strong>an</strong> lead to com-<br />
plete useless measurements if the signal is disturbed too much. This would be the case if<br />
the cabin temperature sensor is positioned in the flow <strong>of</strong> one <strong>of</strong> the air outlets or exposed<br />
to direct sun light.<br />
The ambient temperature <strong>an</strong>d air humidity is usually measured behind (or in) the<br />
front bumper. The placing <strong>of</strong> the measurement devices in the cabin is more difficult due<br />
to the inhomogeneous climate. Today, the sensors are mostly placed in the control unit<br />
in centre console <strong>an</strong>d are <strong>of</strong>ten vented by a small f<strong>an</strong>. In the MUTE, a position without<br />
direct influence from the outlets that is not exposed to solar radiation <strong>an</strong>d is quite central<br />
in the car was found below the mounting <strong>for</strong> the user interface (see Figure 10.6).<br />
The windscreen temperature sensor has to be attached to the glass. In existing<br />
cars it is placed in the rear view mirror fixture or close to it. They all have in common the<br />
position at the top <strong>of</strong> the windscreen since this is the coldest part (neglecting a small area
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