WO2004048137A1 - Sensor for examining the quality of the air and method for examining the quality of the air by means of a sensor - Google Patents

Abstract

The invention relates to a sensor for examining the quality of the air. Said sensor comprises a control input (411) and an adaptation unit (45) which is connected to said input and is used to adjust the sensitivity of the sensor (41).

Description

 Air quality sensor and air quality method using a sensor

Technical field

The invention relates to a sensor for detecting the air quality and a method for detecting the air quality with a sensor. The proposed sensor for detecting the air quality can be used in motor vehicles (motor vehicles), for example for controlling a recirculation flap or an activated carbon filter, which or which part of an air conditioning system is used.

State of the art

In modern vehicles, air quality sensors control the air recirculation flap of the air conditioning system. If the outside air is bad, the air recirculation flap is closed and opened when the outside air is better again. Poor outside air is present, for example, when the concentration of polluted air becomes too high for the vehicle occupants. For this purpose, for example, the NOx concentration and / or is measured the concentration of hydrocarbons in the air surrounding the vehicle.

Whether the air flap should be closed or opened depends on the quality of the ambient air in the vehicle. For this purpose, certain leading gases in the air are constantly monitored. If the concentration of a pilot gas rises above a predefined level or switching gradient, the interior of the vehicle must be protected against the harmful gas in the area surrounding the vehicle, hereinafter also referred to as harmful gas. To this end, the air conditioning system can cause the air recirculation flap to close if other data relevant to the air conditioning system permit this.

The switching level, the switching gradient and the closing time are stored in the known air quality sensors in the air quality sensor. Therefore, these parameters cannot be adjusted to the particular motor vehicle. In addition, these parameters cannot be set by the user and cannot be adapted to the respective environment.

Presentation of the invention

In contrast, the sensor according to the invention for detecting the air quality and the method according to the invention for detecting the air quality with a sensor offer the advantage that the sensitivity can be set at any time and easily. The parameters can advantageously be adapted to the needs of the vehicle occupants.

To this end, the sensor according to the invention for detecting the air quality has the features according to patent claim 1.

The sensor according to the invention for detecting the air quality has a control input and an adaptation unit connected to it, via which the sensitivity of the sensor can be set.

The method according to the invention for detecting the air quality with a sensor has the features according to patent claim 12.

The method according to the invention for detecting the air quality with a sensor comprises the following steps. The sensitivity of the sensor is set via a control input of the sensor and the air quality is then recorded with the sensor depending on the set sensitivity.

Advantageous developments of the invention result from the features specified in the dependent patent claims.

In one embodiment of the invention, the sensitivity of the sensor can be specified via a control byte.

In a further embodiment of the invention, a memory, in particular a read-only memory, is provided, in which different one or more corresponding sensor parameters are stored. For example, an EEPROM can be used as the read-only memory. This means that the individual sensor parameters can be selected using the control byte created as an address in the EEPROM. This means that corresponding sensor parameters are assigned to the individual values of the control byte.

In a further development of the invention, one of the sensor parameters advantageously indicates a certain slope in the measurement signal, the exceeding of this slope causing the sensor to change its signal state at the sensor output.

In a further advantageous embodiment of the invention, one of the sensor parameters specifies a threshold value in the measurement signal, after which the sensor changes its signal state at the sensor output.

Finally, in a further embodiment of the invention, one of the sensor parameters can specify a time period during which the sensor maintains its signal state at the sensor output.

In a development of the invention, a recirculating air flap can be controlled via the sensor output signal.

In a further embodiment of the invention, it is also possible for the transmission of the control byte to be serial, by means of a pulse-width modulated Signal or by means of an analog control signal.

An adjustment means is also advantageously provided, by means of which the sensitivity can be predetermined by a user. This creates a possibility that allows the user to adapt the switching frequency and the closing times to his personal perception and personal needs.

Furthermore, it can be provided in an additional embodiment of the invention that the control input of the sensor is connected to a control output of a control unit of an air conditioning system. This opens up the possibility that the air conditioning system can influence the behavior of the sensor.

The sensor according to the invention can be used in a motor vehicle to record the air quality in the surroundings of the motor vehicle.

Brief description of the drawings

The invention is explained in more detail below with reference to four figures.

FIG. 1 shows in the form of a time diagram the influence of the pollutant level in connection with threshold values on the output signal of the sensor. FIG. 2 shows in the form of a time diagram the influence of the gradient of the measurement signal on the output signal of the sensor.

FIG. 3 shows in the form of a time diagram different output signals of the sensor with locking tents of different lengths,

FIG. 4 shows a possible embodiment of the invention in simplified form in the form of a block diagram.

Ways of carrying out the invention

In the time diagram shown in FIG. 1, the time in seconds is plotted on the x-axis in the lower area and the amplitude on the y-axis. In the upper area of the time diagram, the time is also plotted on the x-axis and the amplitude on the y-axis. Depending on the amplitude of the gas concentration 15 and the threshold values 13 and 14, the two output signals 11 and 12 of the sensor result. As long as the concentration of harmful gases does not reach the first threshold value 14, the level at the output of the sensor is 0. At time t11, the gas concentrations 15 exceed the threshold value 14, which causes the sensor to increase the signal state at its output to level 1 raise, see signal 12. At time tl4, the level of gas concentration 15 drops again below threshold value 14, but the sensor signal remains at level 1 for time period Y2. Only after that, namely at time tlβ If the output signal 12 of the sensor returns to state 0. If the threshold value is set higher than the threshold value 14, which is expressed by the threshold value 13 in FIG. 1, the sensor output signal 11 is obtained at the output of the sensor the gas concentration 15 has exceeded the threshold value 13, which is the case at time tl2, the sensor output signal 11 changes from level 0 to level 1. The gas concentration 15 drops again below the threshold value 13 at time tl3, but the sensor output signal 11 remains for the time period Yl at level 1. Only at time tl5, that is after the time period Yl has passed, does the level of the sensor output signal 11 drop again to the level value 0.

XI in FIG. 1 denotes the time period during which the gas concentration 15 exceeds the threshold value 13. X2 in FIG. 1 denotes the time period during which the gas concentration 15 exceeds the threshold value 14. The sum of the two time periods XI + Yl forms the time period during which the sensor sets the sensor output to level 1 in order to ensure that the air recirculation flap remains closed for this time period. The sum of X2 + Y2 also forms a period of time during which the sensor sets the sensor output to level 1 in order to cause the U - air damper to remain closed for this period of time. The two sums XI + Yl and X2 + Y2 represent le ^¬ diglich two examples for different lengths of time. Which time period should be selected, can the Sensor can be communicated from the outside via a control input on the sensor.

In the time diagram shown in FIG. 2, the time in seconds is plotted on the x-axis and the amplitude on the y-axis. In the upper area of the time diagram, the time in seconds is also plotted on the x-axis and the amplitude on the y-axis as logic level 0 or 1. In the time diagram shown in FIG. 2, the course of the two sensor output signals 21 and 22 depends on the gradient, that is to say the slope or the slope 23 and 24 of the measurement signal 25. At time t21, the increase in gas concentration 25 is greater than the slope 23 indicated by the dashed line. As a result, at time t21 sensor output signal 21 changes from state 0 to state 1. After a certain period of time has elapsed, changes the sensor output signal 21 to the time ^¬ point t22 0 again from the state 1 to the state would place of the slope 24, the slope 23 as the reference slope are selected, would result as a sensor output signal at the output of the sensor provided with 22 marked signal curve, since the gas concentrations 25 never exceed the slope 23.

The minimum closing time is identified in the time diagram in FIG. 2 by tsmin. From Figure 2 it can be seen that the slope was 23 so high that the output signal 22 of the Sen ^¬ sors not change to the state 1, despite a significant increase in gas concentration 25th The steepness 23 is therefore chosen too steep. The maximum steepness with which the steepness of the gas concentration 25 is compared should therefore be chosen to be lower, namely at least such that the minimum closing time tsmin can be maintained. The slopes 23 and

24 are just two examples to explain the influence of the slope on the sensor output signal.

In the time diagram shown in FIG. 3, just as in the time diagram shown in FIG. 2, the time in seconds is plotted on the x-axis and the amplitude on the y-axis. In the upper area of the time diagram, the time in seconds is also plotted on the x-axis and the amplitude on the y-axis as logic level 0 or 1. If the gas concentration 34, as shown in the lower area in FIG. 3, exceeds the threshold value 33, the output signal 31 or 32 of the sensor changes from logic level 0 to level 1. This is the case at time t31. At time t32, the gas concentration 34 drops again below the threshold value 33, but this does not immediately lead to a change in the level in the output signal 31 or 32 of the sensor. Only after a time period Y1 or Y2 has elapsed does the level of the output signal 31 or of the output signal 32 drop back to the logic state 0. This corresponds to the times t33 or t34. The period of time Y1, Y2 can be used to set the time that must elapse before the recirculation flap is opened again after the concentration of pollutants has decreased. The time periods Y1 and Y2 in FIG. 3 are only two Examples to explain the influence of the delay time on the sensor output signal.

In FIG. 4, the basic integration of the sensor according to the invention in an overall system is shown in the form of a block diagram. The output 412 of the sensor 41 is connected to an input 421 of a control unit 42 of an air conditioning system. The sensor output signal 11, 12 from FIG. 1 or 21, 22 from FIG. 2 or 31 or 32 from FIG. 3 is fed to the control unit 42 of the air conditioning system via the output 412 of the sensor 41. A desired sensitivity level of the control unit 42 can be communicated by a user via an input device 45, which is connected on the output side to a further input 424 of the control unit 42. The user thus has the possibility of adapting the switching frequency and the closing times of the air flap 43 to his personal perception. So that the sensitivity level desired by the user can be communicated to the sensor 41, the control unit 42 is connected via one of its outputs 422 to the control input 411 of the sensor 41. Another output 423 of the control unit 42 is connected to an input 431 of the air recirculation flap 43. The air recirculation flap 43 is controlled via the output 423 of the control unit 42. The sensor 41 is equipped with a memory, in particular a read-only memory 44. An EEPROM serves as read-only memory 44. This, in turn, is followed by an adaptation unit 45 which transmits the measurement signal generated by a gas-sensitive field 46 to that generated by the control unit 42 adapts the specified parameters and makes them available at sensor output 412 of the sensor.

The control byte transmitted from the output 422 of the control unit 42 to the control input 411 of the sensor 41 contains information about the sensor parameters to be set. 256 different sensor parameters can thus be set via the 8 bits of the control byte.

Sensor parameters can, for example, the m figure

1 threshold values 13 and 14 shown in FIG

2 steepnesses 24 and 25 shown and / or the closing times Y1 and Y2 shown in FIG. 3. The corresponding values for the threshold value, the slope and the closing time of the sensor 41 are selected from the EEPROM 44 using the control byte. The sensor 41 then forms the corresponding sensor output signal as a function of these variables and as a function of the gas concentration, which is then present at the output 412 of the sensor 41.

The levels 13 and 14, gradients 23 and 24, as well as closing times Y1 and Y2, which are permanently stored in the cells of the EEPROM, are presented to the sensor 41 by transmission of a specific control byte via serial communication, via a pulse-width modulated command or an analog input signal - given. The sensitivity level is thus encoded in the transmitted control byte. Depending on the value transferred, the sensitivity levels stored in the EEPROM are called up. As mentioned, the control byte can be transmitted from the control output 422 of the control unit 42 to the control input 411 of the sensor 41, for example by serial data transmission. As an alternative to this, it is also possible to carry out the transmission of the control byte using a pulse-width-modulated control signal or else using an analog control signal. Which of the above options for data transmission should be preferred depends on the technical boundary conditions.

A specific control byte for setting the sensor parameters can also be specified by the control unit 42 of the air conditioning system without the user. If certain values are set via the air conditioning system, these can influence the control byte to be specified by the control unit 42.

A keyboard, in the form of two keys for a higher and a lower sensitivity, or a rotary wheel, for example, can serve as an input device 45 for adapting the sensitivity of the sensor 41 to personal needs.

The advantage of the invention is that the pollutant levels, the gradients and the closing times can be adapted to the motor vehicle, to the user and to the environment in which the motor vehicle is located. In particular, this can be done without having to remove the sensor and without different calibrations during manufacture. position possible. This creates a possibility that allows the user to adapt the scanning frequency and the locking tents to his perception.

The sensor-specific limit values determined at the same time, i.e. during the calibration, are changed with the control byte. For the limit values and the slope, factors can be displayed with a 1/256 resolution in the range 0-2. There are factors in the range from zero to 255 for the closing times of the air recirculation flap and the activated carbon filter.

The preceding description of the exemplary embodiments according to the present invention is only for illustrative purposes and not for the purpose of restricting the invention. Various changes and modifications are possible within the scope of the invention without leaving the scope of the invention and its equivalents.

Claims

claims 1. Sensor for detecting the air quality, characterized in that a control input (411) and an adaptation unit (45) connected to it is provided, via which the sensitivity of the sensor (41) can be set. 2. Sensor according to claim 1, characterized in that the sensitivity can be predetermined via a control byte. 3. Sensor according to one of the claims 1 or 2, characterized in that a memory (44), in particular a read-only memory, is provided, in which one or more corresponding sensor parameters are stored for different sensitivity levels. 4. Sensor according to claim 3, characterized in that one of the sensor parameters indicates a threshold value (13; 14) in the measurement signal, beyond which the sensor changes its signal state at the sensor output. 5. Sensor according to claim 3, characterized in that one of the sensor parameters indicates a certain slope (24; 25) in the measurement signal, after which the sensor (41) changes its signal state at the sensor output. 6. Sensor according to claim 3, characterized in that one of the sensor parameters specifies a time period (Y1; Y2) during which the sensor (41) maintains its signal state at the sensor output (412). 7. Sensor according to one of the claims 1 to 6, characterized in that a recirculating air flap (43) can be controlled via the sensor output signal. 8. Sensor according to one of the claims 1 to 7, characterized in that the control byte is transmitted serially or by means of a pulse-width-modulated control signal or by means of an analog control signal. 9. Sensor according to one of the claims 1 to 8, characterized in that an adjusting means (45) is provided via which the sensitivity can be predetermined by a user. 10. Sensor according to one of the claims 1 to 9, characterized in that the control input (411) of the sensor (41) is connected to a control output (422) of an air conditioning control unit (42). 11. Use of the sensor according to one of claims 1 to 10 in a motor vehicle for detecting the air in the environment of the motor vehicle. 12. A method for detecting the air quality with a sensor, characterized in that a Control input (411) of the sensor (41), the SENS ^¬ friendliness of the sensor (41) is set, and from which a ^¬ sensitivity provided good air is detected by the sensor (41) is then dependent.