Patent
1988-06-03
1990-06-05
Williams, Hezron E.
B60H 124
Patent
active
049304070
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a sensing system for controlling air circulation valves in motor vehicles which includes a semiconductor as a sensor element for pollutants and as an electronic preconditioning of the sensor signal.
THE RELATED ART
Semiconductors which modify their inner resistance when pollutant and other gases are detected, are widely used.
Their operating principle is based on the fact that the sensor, together with an external resistor, form a voltage divider. The reading of the medium voltage measures the content of pollutants in the air.
Further, it is known that the semiconductor sensors are sensitive to temperature. Therefore, it has already been proposed to compensate this sensitivity to temperature, for instance, by wiring the external resistor with a NTC-resistor, whose characteristics correspond to the temperature characteristics of the sensor.
Further, it is known that the sensitivity of the sensor depends on the humidity of the air. As a rule, the sensors become more sensitive with increasing humidity. In order to compensate for the effects of temperature and humidity, a considerable effort is required to adapt the circuit arrangements.
In the use of such sensors for the control of air-circulation valves in motor vehicles, this transverse sensitivity preferably towards humidity can lead to different switch points, which are subjectively and objectively incorrect.
It has therefore been proposed to differentiate the detected voltage signals and to switch each only then when a persistent modification in the pollutant level occurs. This method eliminates all influences which can be traced back to temperature or humidity. This method, wherein only the difference level is transmitted, has however the disadvantage that in the case of long-term static situations with simultaneous high pollutant content, the switching process is cancelled after a certain time.
Besides, in this differentiation, it is very important whether the increase of the pollutant concentration occurs rapidly, slowly or even creepingly. Depending on the layout of the differentiation element, which--electrically speaking--is a high-pass filter, very slow increases in the pollutant concentration are not detected.
For instance, when the vehicle moves along a country road with clean environmental air, the presence of another vehicle becomes particularly disturbing because the sensitivity to smell has been enhanced.
In the reversed situation, in very heavy inner-city traffic, it is not desirable that the fresh-air valve of the vehicle remain almost permanently closed. Because the sensitivity towards pollutants is clearly dimished, it is desirable in this case to also decrease the response sensitivity.
Departing from this state of the art, it is the object of the present invention to create a sensor without the aforementioned disadvantages, which not only absolutely eliminates the influences of temperature and humidity, but also automatically adjusts its sensitivity towards pollutants.
A sensing system for controlling air circulation valves or motor vehicles is herein provided. The system comprises a pollutant detecting and electronic preconditioning sensor means in the form of a semiconductor, this means generating one or more signals related to a measured level of pollutants, and a switching amplifier receiving said signals, the amplifier having a variable operating switch point dependent upon the received signals, and a means for integrating the one or more signals. Through this arrangement is achieved short-term modifications of the sensor signal leading to the desired switching of the system while still permitting changing the switch point within predetermined limits accommodate temperature and humidity drift of the sensor. Additionally, the system may be adjusted to accommodate the subjective judgment of the human sense of smell such adjustment is important since it is known that the sense of smell reacts sharply to even small amounts of pollutants, if correspondingly conditioned by a pre
REFERENCES:
patent: 3418914 (1968-12-01), Finkin
patent: 4306444 (1981-12-01), Hattori et al.
patent: 4352321 (1982-10-01), Fukui et al.
patent: 4437391 (1984-03-01), Eguchi et al.
patent: 4458583 (1984-07-01), Fukui et al.
patent: 4478049 (1984-10-01), Fukui et al.
patent: 4733605 (1988-03-01), Holter et al.
patent: 4742763 (1988-05-01), Holter et al.
Holter Heinz
Rump Hanns
Dubno Herbert
Holter Heinz
Roskos Joseph W.
Williams Hezron E.
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