JPH0648162A - Control method for vehicle interior ventilation system - Google Patents

Abstract

(57) [Abstract] [Purpose] In a method for controlling a vehicle indoor ventilation device, which detects indoor pollutant concentration and outdoor air pollutant concentration, and operates the ventilation device depending on at least one switching threshold of pollutant concentration, Improvements should be made to account for the fundamental load of pollutant concentrations in indoor air, which is normally changing. A threshold is set as a function of the indoor pollutant concentration, and the threshold is tracked and controlled according to the tendency of the indoor pollutant concentration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the concentration of indoor pollutants and the concentration of outside air pollutants, and determines at least one of the pollutant concentrations.
The present invention relates to a method for controlling a vehicle interior ventilation device, which operates the ventilation device depending on one switching threshold value.

[0002]

2. Description of the Prior Art A method of this kind is known from DE-A 2941305. In the method according to this publication, the pollutant concentration value for the outside air and the pollutant concentration value for the indoor air are measured using a sensor, and these two values are compared with a threshold value, respectively. Based on this comparison, a control signal for operating the ventilator is generated.

The following is already known from German Patent Publication No. 3304324. That is, it is known that the threshold value for the pollutant concentration value in the outside air, which is obtained by using the sensor signal, is tracked and controlled according to the tendency of the sensor signal during the operation cycle. This means the following: That is, it means that the introduction of outside air is performed only depending on the basic load of the changing outside air. No consideration is given to the concentration of pollutants in indoor air with this method. Further, the tracking control of the signal does not consider the characteristics of the semiconductor gas sensor. The instability of the semiconductor gas sensor that causes the signal drift depends on parameters such as the humidity of the air or the period of use. In addition, this type of sensor also responds to the gas that causes a chemical reaction on the sensor surface as well as the gas (CO, NOx) to be measured.

[0004]

An object of the present invention is to detect the indoor pollutant concentration and the outdoor air pollutant concentration, and to operate the ventilation device depending on at least one switching threshold of the pollutant concentration. The control method of the device is to improve so that the basic load of fluctuating pollutant concentration in the indoor air is taken into consideration.

[0005]

According to the present invention, the above-mentioned problem is solved by setting a threshold as a function of the indoor pollutant concentration and controlling the threshold to follow the tendency of the indoor pollutant concentration. It

[0006] The advantage obtained by the method according to the characterizing part of claim 1 of the present invention is that the fundamental load of pollutant concentration in the indoor air, which is normally fluctuating, is taken into account. . As a result, the control system becomes responsive to the pollutant concentration in the indoor air that is directly felt by the passengers of the vehicle.

Advantageous refinements of the invention are stated in the dependent claims.

Particularly preferably, a switching threshold for closing the outside air inlet and a switching threshold for opening the outside air inlet are provided. These switching thresholds are set depending on the pollutant concentration in the indoor air, and follow-up control is performed according to the progress of the characteristic amount. In addition, at least the switching threshold for the closing of the outside air introduction part is subjected to follow-up control additionally depending on the operating time of the sensor. Furthermore, in addition to the absolute sensor signal, the first derivative with respect to time is evaluated as a characteristic quantity representing the change in concentration. This allows the sensor signal evaluation to be matched to the special properties of the semiconductor gas sensor when measuring the concentration of pollutants in the open air. As a result, instability of the absolute sensor signal (signal drift) no longer influences the evaluation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An outside air introduction section in a vehicle compartment is controlled by a ventilation device. For this control, the pollutant concentration in the outside air is compared with the pollutant concentration in the indoor air, and on the basis of this comparison a control signal used for operating the ventilation system is generated.

Since CO ₂ represents a direct measure of air consumption in a closed room, it is used as a reference gas for the quality of the air in the vehicle compartment. In a closed vehicle compartment with passengers, CO ₂ increases due to human breathing movements. Further, CO ₂ is also evaluated as an indirect measure of the influence on the degree of air pollution due to smoking, sweating of the human body, and the like. According to the present invention, the CO ₂ indoor concentration is calculated by the following equation.

LM × dK (t) / dt = SZU + SQU-Sab (1) In this case, LM is the amount of air in the vehicle compartment, K (t) is the CO ₂ indoor concentration to be detected, and SZU is from the outside to the interior. of CO ₂ uptake, SQU the uptake of CO ₂ from the passenger, S
ab is the amount of CO ₂ released from the room to the outside.

Furthermore, the following two expressions are established.

SZU = KCO ₂ × m Sab = K (t) × m In this case, KCO ₂ is the CO ₂ concentration in the outside air, and m is the flow rate of the air passing through the room when the outside air introduction part is opened.

As a result, when the outside air introducing portion is open, the above equation (1) is the following differential equation.

LM × dK / dt = m (KCO ₂ −K (t)) + SQUA (2) Further, when the outside air introduction part is closed, the following equation is obtained.

LM × dK (t) / dt = SQUA (3) Here, the above equation (2) is solved by the following equation.

[0017]

[Equation 1]

In this case, KAusg1 is the indoor concentration at the time when the outside air introducing section is opened. Further, the equation (3) can be solved by the following equation.

K (t) = (SQUA / LM) t + KAusg2 (5) In this case, KAusg2 is the indoor concentration at the time when the outside air introduction part is closed.

In order to calculate the CO ₂ indoor concentration K (t), the parameters included in the equations (4) and (5) must first be obtained. The air flow rate m is a function of the vehicle speed v and the power P consumed by the ventilator fan. A corresponding air flow rate m is associated with this set of values consisting of v and P. This correspondence is different for each vehicle and is stored in the ROM of the calculation unit. The air flow rate m is continuously determined by the calculation unit. The air volume LM in the vehicle compartment is also stored as a constant in the calculation unit.

The CO ₂ uptake SQU is caused by the breathing of the vehicle occupant. This CO ₂ uptake SQ
U is calculated as follows. That is, it is determined by transmitting the number of passengers to the calculation unit and multiplying this number by the average value for the amount of CO ₂ exhaled by a person per unit time. The number of passengers is obtained, for example, via a seat terminal.

In the present invention, as the CO ₂ intake SZU through the outside air, the average CO ₂ concentration in the outside air = 400 p
pm is also filed in the calculation unit as a constant. Indoor concentration KAusg1 at the time of opening the outside air inlet
And the indoor concentration KAusgl2 at the time of closing the outside air introduction part
Is likewise intermediately stored in the calculation unit. The determination of parameters involves more or less error. In this case, the determination of the air flow rate m is particularly critical. As a result, the calculated CO ₂ indoor concentration K (t) deviates from the actual value. The error that occurs in this case increases with time t. That is, the exponent in the above formula (4) makes it significantly larger. Therefore, the calculated value is corrected at an appropriate reference base location (reference position value). In the embodiment of the present invention, the reference position is a pair of values [t, K (t)] indicating one concentration K (t) that is sufficiently accurate at a predetermined time point t. This pair of values is supplied as an initial value, and by this initial value, the CO ₂ indoor concentration K (t)
The method for calculating is repeatedly started anew.

In FIG. 1, the CO ₂ indoor concentration K calculated when the outside air introducing portion is opened and when it is closed.
The elapse of (t) is shown with respect to time t. Time t0
The calculation of the CO ₂ indoor concentration K (t) designated by the reference sign KAusg1 is performed according to the equation (4) when the outside air introducing portion is opened. At time point t1 (corresponding to time ts in the flowchart of FIG. 2), the outside air introduction part is closed, and the concentration value KAusg2 is intermediately stored. The CO ₂ indoor concentration K (t) here is calculated according to the above equation (5). At time t2, the outside air introduction section is opened again,
Whereby a new density value KAusg1 'is intermediately stored, a new calculation of the CO ₂ indoor concentration K (t) by using the density value is performed according to the equation (4). The time point t2 is indicated by to in the flowchart of FIG.

As is clear from the course of the CO ₂ indoor concentration K (t) calculated when the outside air introduction portion is opened, the function with respect to the time amount t is the CO ₂ outside air concentration KCO ₂ and the CO from the passenger. _{2 It} is asymptotically approximated to the value obtained by adding the ratio with the incorporated SQU. Therefore, the parameter error of the air flow rate m is inversely related to the limit value.

The above-described correction at the reference position is performed in the following cases. That is, it is performed when the CO ₂ chamber concentration approaches the asymptotic limit value concentration by the value A. Figure 1
Then, this value A is at time t3.

The reference position is set in the following cases, for example. That is, the calculated CO ₂ indoor concentration K (t)
Is 10%, the asymptotic limit value concentration KCO ₂ + SQ /
It is set when it exceeds m. That is, when the following condition: {K (t) -K (t → ∞)} / {K (t = to) -K (t → ∞)} × 100% ≦ 10% (6), The CO ₂ indoor concentration K (t) is set to the concentration value represented by the following equation.

K (t) = K (t → ∞) = KCO ₂ + SQUA / m (7) The above condition (6) satisfies the following condition t ≧ 2.3 × LM / m (8) Will be charged to. M in the formula (7) is a constant.

However, since these do not apply to the actual driving situation, the following is performed. That is, the opening time to of the outside air introduction unit is temporarily stored,
After that, the instantaneous air flow rate m flowing through the vehicle interior is detected from the instantaneous traveling speed v and the electric power P consumed by the ventilator fan. From these values for the air flow rate m, which are sequentially obtained from the opening time point, an average value is successively formed. The added air flow rate m at each instant is compared with an average value formed from the values of the preceding air flow rate m. If the instantaneous air flow rate m is greater than the average value, the instantaneous air flow rate m is used only to update the average value. The instantaneous air flow rate m is
If it is smaller than the average value, the average value and the belonging time t ′
= T-to is used to check the condition of equation (8) for correction at the reference position. When this condition is satisfied, the above equation (7) containing the average value for m is included.
The correction at the reference position is performed using the limit value according to. On the other hand, when the equation (8) is not satisfied, the instantaneous air flow rate m is also used only for updating the average value. This ensures that: That is, it is guaranteed that the correction at the reference position is performed only within the 10% tile by the above equation (6).

However, a direct comparison between these concentrations does not make much sense because of the different gas types. Therefore, it is necessary to weight these different gases based on their effects on human organs. In the present invention, CO is defined as a concentration range which is regarded as not harmful to human health.
0 to 10 ppm for CO _{2 and} 0 to 10 for CO ₂ .
00 ppm is defined. Therefore, CO ₂ concentration
The densities must be weighted by a factor of 100. If further or other gases in the outside air (for example NOx) are to be taken into account, corresponding weighting factors can be determined, for example on the basis of MIK or MAK data.

In addition to the above calculation of the CO ₂ indoor concentration, the concentration of pollutants in the indoor air can be measured using a special CO ₂ sensor. However, it is also conceivable to use other guide gases such as CO ₂ for the detection of pollutant concentrations in room air.

The pollutant concentration in the outside air is detected using a sensor mounted on the vehicle. For that purpose, the resistance value R of the sensor is measured. In this case, the resistance value R of the sensor is a measure for the pollutant concentration. Sensor resistance R
Is also used as an absolute value R (t) with respect to time, and also as a change in the pollutant concentration at the time of deposition of pollutant gas by the derivative (dR (t) / dt) of the function R (t). The magnitude and polarity of this characteristic amount indicate a measure for the change in concentration. In this case, the characteristic amount dR
It should be noted that (t) / dt depends on the gas coverage on the sensor surface. At a predetermined increase in density, the characteristic amount becomes relatively small as the degree of deposition increases. That is, the sensor is displaced according to the saturation state and its operating point. Since the resistance value R of the sensor is used as a measure for the adherence, the operating point is also set accordingly.

In an embodiment according to the invention, the sensor resistance value R (t) with respect to time is compared with the CO ₂ chamber concentration K (t). On the other hand, two CO ₂ indoor concentration values are determined as the threshold values S1 and S2. In this case, the threshold value S1 indicates the closing of the outside air introducing portion, and the threshold value S2 indicates the opening of the outside air introducing portion.

Next, a method for controlling the outside air introduction section will be described. The method starts in step 1 with the opening of the outside air inlet. Initial values for the switching thresholds S1 and S2 are intermediately stored in step 2 in the calculation unit. In this case, this initial value is always in the middle region of the CO ₂ chamber concentration. In step 3, the pollutant concentration change dR /
A comparison is always made between dt and the switching threshold S1. If the following condition is satisfied: dR / dt ≦ S1 <0, the outside air introduction part is closed according to step 4. At the same time, in step 5, the sensor signal R (ts) at the time of closing is stored in the calculation unit.

Step 6 while the outside air introduction section is closed
Will always check the following condition: dR / dt ≦ S1. This condition means that the pollutant concentration will continue to rise. If the pollutant concentration no longer rises, the absolute value of the sensor signal R (t) is compared in step 7 with the sensor signal R (ts) at the time of closing the outside air inlet. The following conditions: {R (t) -R (ts)} / R (ts) ≧ S2 [K (t
s)] <0 is satisfied, the outside air introducing unit is operated in the corresponding step 8
Is newly opened at. Sensor signal R at opening
(To) is filed in the calculation unit in a corresponding step 9.

In the following step 10, the instantaneous CO ₂ indoor concentration K (t) and the saturation effect of the pollutant sensor already mentioned above are taken into consideration. This is performed by changing the switching threshold S1 for interrupting the introduction of the outside air depending on the CO ₂ indoor concentration K (t). That is, S1 [K
(T)]. In order to consider the saturation of the sensor, the value for the switching threshold S1 is corrected according to the sensor resistance value R (t). In this case, the whole value range for the resistance value R (t) of the sensor is a small part (sub).
It is divided into areas. The correction factor F for only one partial area
[R (to)] is assigned. By multiplying this correction coefficient by the switching threshold S1, the correction amount for the switching threshold S1 is obtained. The calculation operation and the storage function are performed by a calculation unit.

The correction value for the switching threshold S1 is
In step 10, the pollutant concentration change dR / dt is compared. If the following conditions are satisfied: dR / dt ≦ F [R (to)] S1 [K (t)], the outside air introduction part is closed in step 11, and the sensor signal R (ts) at the time of closing. Are stored in step 12. While the outside air introduction part is closed, the pollutant concentration change with time dR / d is similar to the first closed loop according to step 6 described above.
t is the corrected switching threshold S1 and step 13
Are compared again in.

If the increase in the pollutant concentration change no longer occurs, the control feeds back to step 7 where a comparison is made with the instantaneous sensor signal R (ts) at the last closing of the outside air inlet. . The following conditions: {R (t) -R (ts)} / R (ts) ≧ S2 [K (t
s)] <0 is satisfied, the outside air introduction unit is newly opened in step 8. In this case, the sensor signal R at the time of opening
(To) is also stored. The two switching thresholds S
The comparison cycle for 1 and S2 is repeated during the operating period.

The changes in the switching thresholds S1 and S2 act as follows depending on the CO ₂ indoor concentration K (t) and the sensor signal R (t).

Change of influence amount Effect on switching threshold Action CO ₂ indoor concentration Increase of switching threshold S1 The closing condition is relaxed and K (t) decreases. That is, the device is closed when the degree of outside air concentration (opening of the outside air introduction part) is relatively low. Sensor signal R (t) Increase in switching threshold S1 Decrease in closing condition Relaxation Correction to operating point Sensor signal R (t) Switching Decrease in threshold S1 The closing condition is severely increased. Adjusting to operating point CO ₂ indoor concentration Switching threshold S2 decrease Opening condition is relaxed and K (t) increases. The device is opened when the outside air concentration is comparatively high (closed outside air inlet).

[0040]

According to the present invention, the fundamental load of pollutant concentration in indoor air, which is normally changing, can be taken into consideration. As a result, the control system responds to the pollutant concentration in the indoor air that is directly felt by the passengers of the vehicle.

[Brief description of drawings]

FIG. 1 is a diagram showing the progress of calculated CO ₂ indoor concentration with respect to time.

FIG. 2 shows a flow chart of the method according to the invention for controlling the outside air inlet.

[Explanation of symbols] K (t) CO ₂ indoor concentration S (t) outdoor air concentration R (t) sensor resistance value S1 switching threshold for opening S2 switching threshold for closing KAusg1 concentration value at opening KAusg1 'concentration at opening Value KAusg2 Concentration value at the time of closing KAusg2 'Concentration value at the time of closing LM Air volume m Air flow rate

Front Page Continuation (72) Inventor Günter Lille Germany Buehlertal Hauptstraße 6 (72) Inventor Bernd Schumann Rüttesheim Daimlerstraße 23

Claims (12)

[Claims] 1. A method for controlling a vehicle indoor ventilation device, comprising: detecting an indoor pollutant concentration and an outdoor air pollutant concentration, and operating the ventilation device depending on at least one switching threshold of the pollutant concentration. Control of a vehicle indoor ventilation device, characterized in that a switching threshold is set as a function of (K (t)), and the switching threshold is tracked and controlled according to the tendency of the indoor pollutant concentration (K (t)). Method. 2. The follow-up control of the switching threshold value additionally depending on the tendency of the pollutant concentration of the outside air.
A method for controlling the vehicle interior ventilation device described. 3. A first switching threshold value (S1) for closing the outside air introducing portion and a second switching threshold value (S2) for opening the outside air introducing portion are provided, and the two switching threshold values (S1) and 2. The method for controlling a vehicle interior ventilation device according to claim 1, wherein (S2) is compared with a sensor signal representing a pollutant concentration in the outside air. 4. A first derivative with respect to time of a sensor resistance value at the time of deposition of pollutant gas is formed as a sensor signal when the outside air introduction part is open, and the result of the evaluation is used as a switching threshold (S1). The control method of the vehicle interior ventilation device according to claim 3, wherein the outside air introduction part is closed when the following condition is satisfied: dR (t) / dt ≦ S1 <0. 5. The control method for a vehicle indoor ventilation device according to claim 4, wherein the switching threshold value (S1) is controlled so as to follow the tendency of the indoor pollutant concentration and the sensor resistance value (R (t)). 6. The switching threshold value (S1) is increased when the indoor pollutant concentration (K (t)) decreases.
The method for controlling the vehicle interior ventilation device according to claim 5. 7. The switching threshold value (S1) is increased when the sensor signal (R (t)) is decreased, and the switching threshold value (S1) is decreased when the sensor signal (R (t)) is increased. The method for controlling the vehicle interior ventilation device according to claim 5. 8. The sensor resistance value (R
(T)), the following condition, {R (t) -R (ts)} / R (ts) ≧ S2 <0, is satisfied, the outside air introduction part is opened, and in this case, The method for controlling a vehicle interior ventilation device according to claim 3, wherein the sensor resistance value (R (t)) is a sensor signal at a preceding closing time. 9. The method for controlling a vehicle indoor ventilation device according to claim 8, wherein the switching threshold value (S2) is lowered when the indoor pollutant concentration increases. 10. The control of the vehicle interior ventilation device according to claim 1, wherein each starting value for the switching thresholds (S1) and (S2) is set in an intermediate region of the indoor pollutant concentration. Method. 11. The method for controlling a vehicle indoor ventilation device according to claim 1, wherein a CO ₂ indoor concentration is measured and / or calculated as the indoor pollutant concentration (K (t)). 12. The method for controlling a vehicle indoor ventilation device according to claim 11, wherein the pollutant concentration in the outside air is weighted with respect to the CO ₂ indoor concentration in accordance with the influence on the human body.