DE3731745C3 - Method for controlling a vehicle ventilation device - Google Patents

Description

The invention relates to a method for control a vehicle ventilation device according to the preamble of Claim 1.

It is known that increased concentrations of pollutants, that act on the occupants of motor vehicles, can lead to health problems.

Therefore, the supply of outside air has been proposed then interrupt when the car passes a zone in the increased pollutant concentrations noticeable are. Such concentrations are usually time temporarily at traffic lights, at certain intersections and to be found in column traffic.

The closing of the fresh air supply is preferred via a so-called air recirculation flap by a sensor let who is sensitive to pollutants.

In Japanese patent application Sho 58-38219 and  Sho 59-39330 describes a method in which Use a sensor to achieve another goal finds its evaluation electronics with non-constant Switching level works.

DE 33 04 324 A1 shows a method for controlling a Vehicle ventilation device, in which depending on the level of pollution present outside the vehicle ventilation is interrupted and / or switched to recirculation mode and then influencing the ventilation takes place when the determined by a suitable outdoor sensor the actual value corresponding to the external load is greater is as its reference value, which is an average of that of corresponds to the actual value delivered to the outdoor sensor. With this known methods, the reference value is different Formed way. On the one hand, it is possible an additional reference sensor to obtain the reference value to the existing outdoor sensor. This The reference sensor is the outside air in a different effective volume exposed like the measuring sensor. The effective volume ratios between the measuring sensor or external sensor and the Reference sensors are selected so that the measuring sensor is also on brief increases in the concentration of pollutants in the Outside air responds, whereas the reference sensor only a comparatively continuous and ongoing Increases in the concentration of pollutants in the outside air detected. On the other hand, there is a method of obtaining the reference value shown in which by means of electronic and  electrical components the reference value from the part of the Measurement or external sensor detected measurement signal is obtained.

Apart from the fact that with the different described above Procedures a comparatively large one the reference value follows with the known process alternatives, the actual Value of the measuring or external sensor to a level that is clearly above the barrier above which the import of additional outside air into the vehicle interior u. U. can lead to health problems. The same the reference value follows the actual value below one lower bound, which is actually not necessary Switching processes result in an unstable operating behavior of the vehicle ventilation system.

The invention is based, based on the task State of the art described above a method for Control of a vehicle ventilation device to create that on the one hand, can be carried out with less equipment is and by means of which on the other hand it is excluded that a The inside of the vehicle is ventilated with outside air if the pollutant content of the outside air has a predeterminable maximum value exceeds.

This object is achieved in that the influencing of the ventilation via a microprocessor program-controlled  takes place, the change of to one between a maximum and a minimum basic value Range from the reference value According to the program, the actual values of the outdoor sensor are permanently formed calculated using any mathematical method.

As a result, a reference switching level becomes the non-arithmetic mean educated. The program constantly compares in real time, using the current sensor level the developing reference level. Checked at the same time the program whether the reference level is greater or less than is the current sensor level. If a deviation is found, is into the register from which the reference value is read a bit is added or subtracted. The software and the size of the register are designed so that the Time required to change the value of the register from 00 to change to FF, freely selectable between preferably 5 and is 30 minutes. The result of this measure is that the rate of change of the register (Delta U to Delta t) is constant and linear. Over a fixed maximum or below a set minimum, the reference value do not rise or fall. This is predetermined by the Basic parameters guaranteed. The air recirculation flap is closed if the actual value is greater than the reference value, and they opens when the actual value is less than the reference value is.

Advantageous further developments result from the  Subclaims.

The invention is explained in more detail below with reference to FIGS. 1 and 2.

After starting the program ( 1 ) it is first checked whether the ignition is switched on ( 2 ). If this is not the case, the program remains in an endless loop. If the ignition is switched on, the sensor is - preferably - overheated in a preheating phase ( 3 ) with a higher voltage; this has the purpose of "burning" the sensor of contaminants. Furthermore, the fresh air flap is opened during the entire preparation phase. After the preheating phase ( 4 ), the sensor heating is reset to a normal value ( 5 ). In a subsequent calming phase ( 6 ), one waits until the sensor levels normalize (in the preferred embodiment, this time is approximately 30 seconds). Subsequently, the AD converter value is read in for the first time under ( 7 ) and stored under U _mom and evaluated with the exponent X under U _mom *. In step ( 9 ), the value of U _{mom is} checked to determine whether it lies within plausible limits; if this is not the case, this branches to step ( 20 ), in which a fault message is issued or an error handling routine is processed. In the event that the sensor values should normalize and the program thus finds out from the error loop formed by steps ( 20 ), ( 21 ), ( 22 ), step ( 8 ) ensures beforehand that the program does not have an undefined one The value for U _ref begins by setting U _ref to an average sensor level U _fix .

If the plausibility check under ( 9 ) has a positive result, then all the required parameters are initialized under ( 10 ), the reference value being formed by applying a constant to the previously read sensor value U _mom - preferably 10% of the converter range ; this value for U _ref thus obtained must be within the limits formed by U _ref.max and U _ref.min . The preparation phase is completed with step ( 10 ). The actual main program begins with step ( 12 ), in which the AD converter value is read in again. In the next program step ( 13 ), the comparison between U _mom and U _{ref takes} into account U _mix (U _mix is the voltage from which the flap is constantly closed). If the weighted level is U _mom * ≦ U _ref * (the star indicates the inclusion of U _mix ), a signal to open the flap is given ( 25 ). If the other condition exists (U _mom * ≦ λτ U _ref *), a signal is given to close the flap ( 14 ). In both parallel program branches, a program step under ( 26 ) or ( 15 ) is now provided as an option, by means of which an adaptation of the learning behavior depending on the frequency of pollutant peaks or the duration of the pollutant level can be achieved; in both cases, running through the individual program branches resets the learning behavior in the respective other program branch. This is followed by steps ( 27 ) and ( 16 ), in which a decision is made as to whether the next adjustment of the reference value is necessary. If the condition for adapting the reference level is given, ie (t ₁ ≦ λτ n _f · Δt) or (t ₁ ≦ λτ n _r · Δt), it is ensured before (actually) setting the reference level under ( 29 ) or ( 18 ) that the reference value cannot grow below the limit U _ref.min or above the limit U _ref.max (program _step ( 28 ) or ( 17 )).

The loop counter t _{1 is then} reset to 0 in both cases (steps ( 30 ) and ( 19 )). If the condition under ( 27 ) or ( 16 ) was not met, the loop counter is increased ( 23 ) and a time delay ( 24 ) ensures that all loop passes are synchronized. If it turns out in program step ( 22 ) that the read AD converter value is outside the permitted range, program step ( 20 ) is again started in which a fault message is issued and an error routine is processed. After reading in the AD converter value under ( 21 ), the plausibility of the read sensor values is checked again ( 22 ). If the sensor values are normalized, a possible fault message is deleted in program step ( 31 ). After checking again whether the ignition is still switched on ( 11 ), a new program cycle begins with the branching of the program to program step ( 12 ). If the ignition is switched off, the program branches to program step ( 2 ) and waits until the ignition is switched on again.

The line shown in FIG. 2 U _mom represents the level at the sensor. For the sake of simplicity, level jumps are idealized as rectangular functions.

The dashed line U _ref shows the comparison value formed from U _mom .

It can be seen that this always changes linearly, regardless of the level jump at U _mom . The slope can be selected as desired. U _ref cannot be moved beyond a specified maximum or minimum. The air recirculation damper responds when U _mom becomes larger than U _ref and opens in the opposite direction.

Claims (6)

1.Method for controlling a vehicle ventilation device, the ventilation being interrupted and / or switched to recirculated air mode as a function of the pollutant level outside the vehicle, and the ventilation is influenced when the actual load determined by a suitable outside sensor corresponds to the outside load -Value is greater than a reference value, which corresponds to an average value of the actual values supplied by the outdoor sensor, characterized in that the ventilation is influenced in a program-controlled manner by a microprocessor, the change in the range lying between a maximum and a minimum basic value limited reference value is calculated from the actual values of the outdoor sensor that are permanently determined according to the program, using any mathematical method. 2. The method according to claim 1, characterized in that that the amount of change of the reference value constant until the basic values are reached is, therefore always forms a linear function whose Steepness can be chosen arbitrarily. 3. Procedure according to at least one of the preceding Claims, characterized in that the amount of change when changing to positive or negative direction can be different. 4. Procedure according to at least one of the previous claims, characterized in that the maximum closing time of the air damper from Program to any value to be set is limited. 5. The method according to at least one of the preceding claims, characterized in that when using preferably semiconductor sensors (SnO ₂ sensors), the program mathematically linearizes the design-strongly curved characteristic of the sensors. 6. Method according to at least one of the preceding Claims, characterized in that the heating power required by the sensors commissioning program-controlled by one any amount is raised by from Program the cycle ratio of those used for heating DC voltage is changed.