Boots – shoes – and leggings
Patent
1996-02-13
1998-08-11
Voeltz, Emanuel Todd
Boots, shoes, and leggings
364506, 36455101, 73 232, 73 2331, 73 3105, 422 94, 422 98, G01N 3100
Patent
active
057936455
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of PCT/EP94/02742 filed Aug. 18, 1994 and based, in turn on German application P 43 28 218.0 of Aug. 21, 1993 under the International Convention.
FIELD OF THE INVENTION
The present invention relates to the use of sensors for the purpose of triggering an electric impulse when there are increased concentrations of gases (target gases) to which the sensor element or elements sensitive. (=target gases).
More particularly, an application of the invention is interruption of the air supply to a motor vehicle cabin when due to the emissions of other vehicles, there is an increased concentration of noxious or toxic gases such as carbon monoxide, nitrogen oxides, sulfur dioxide, partially burnt hydrocarbons, etc. in the air supply to the vehicle cabin.
BACKGROUND OF THE INVENTION
It is known to use various sensors for detecting concentrations of various gases, for instance:
______________________________________ Tin dioxide (SnO.sub.2)
for all oxidizable gases
Phthalocanine for reducible gases
Tungsten trioxide (WO.sub.3)
for nitrogen oxides.
______________________________________
For the evaluation of the signals it is known to trigger the switching signal not when an absolute level is reached, but rather then when the sensor or sensors detect an increased concentration of the target gas in relation to the average level.
Since the sensors are subject to a certain drift, being mostly cross-sensitive with respect to air humidity, and have to operate in areas with very different basic pollutant levels, it has been proposed to differentiate the sensor signal from the background via an electric high pass filter so that the noxious substances resulting from other motor vehicles give rise to clearly differentiated switching pulses to contrasted with the above-mentioned background effects. If the basic frequency of the high-pass filter is selected so that in contrast to the slower changes these pulses (target impulses) are transmitted, each relevant deterioration of the level of noxious substances will advantageously lead to a switching signal. It has been further proposed to differentiate the signal many times, so that even smaller signal changes can be evaluated (see EP 87 00 592).
Since, as a rule, sensors react quickly to a target gas, but are significantly slower in restoring to the initial value, this method is only satisfactory for generating the command "interrupt air supply", but the cancellation command "reopen air supply" is not produced as satisfactorily.
It is known to continuously build up the average value of the sensor signal over a certain time period (e.g. for 10 minutes) and to compare the actual (instantaneous) sensor value with this average value. The signal "close air supply", as well as the signal "open air supply" can be derived therefrom satisfactorily. Details are described in EP 87 00 592 from 1986/87. However for this method sensor signals of a certain amplitude are required. In the case of very small sensor signals, uncertainties in their evaluation occur.
SUMMARY OF THE INVENTION
According to the invention it is therefore proposed to factor in the signal changes as such for evaluation, whereby the consideration of behavior over time plays an essential part.
In particular, the method for evaluating sensor signals has the purpose of generating switching pulses which, via suitable setting elements and air supply ducts, influence the air supply to an inner space, preferably the cabin of a motor vehicle. The air supply is interrupted in the presence of a gas concentration representing a switching criterium or the supplied air is passed through a filter system before it reaches the inner space, i.e. the supply of air from a particular source is cutoff. The initial state is restored, i.e. air supply from the original source is restored, when the quality of the ambient air improves.
When the sensors have an electrical resistance which reduces in the presence of the target gas, an integral i
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Hiller Jorg
Pieper Norbert
Rump Hanns
Dubno Herbert
I.T.V.I. International Techno Venture Invest Aktiengesellschaft
Smith Demetra
Todd Voeltz Emanuel
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