JPH0314134B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an air pollution detection method for an automatic air conditioning control device for a vehicle, which detects air pollution by matching human olfactory characteristics. Conventionally, it is known that vehicles are equipped with automatic air conditioning control devices. An automatic air conditioning control system for a vehicle has gas sensors installed inside and outside the vehicle cabin.The internal and external gas sensors sense the degree of contamination inside and outside the vehicle cabin, and a computer processes this data as data to control the operation of the damper and blower motor. It operates to appropriately select the state of outside air introduction, ventilation, or inside air circulation. Specifically, for example, if the level of pollution from cigarette smoke or carbon dioxide gas (CO ₂ ) associated with unpleasant crowds increases, it will be necessary to bring clean outside air into the cabin, and the level of pollution inside the cabin will decrease. All you have to do is circulate your inner air. However, when actually attempting to automatically operate the vehicle air conditioning control device based on the degree of contamination of the air inside and outside the vehicle interior, the following problem arises. In other words, for example, if the air inside the vehicle is dirty and the air outside the vehicle is clean, the system will operate to provide ventilation, but whether the air inside the vehicle is dirty or not depends on the occupant's sense of smell. Therefore, it is difficult to accurately determine whether or not something is contaminated using a gas sensor that simply detects the magnitude of a physical quantity. In other words, it is difficult to make a driver use the same sense as a human to make the decision to replace the dirty air inside the vehicle with clean air from outside. In view of the above-mentioned problems, the present inventor has created the present invention to effectively solve the problems. An object of the present invention is to make a method for detecting the degree of pollution inside and outside the vehicle interior consistent with the human olfactory characteristics in an automatic air conditioning control system for a vehicle, and thereby to detect the degree of contamination inside _and outside the vehicle interior. The purpose is to make judgments similar to how humans feel, and to perform effective air conditioning control that matches human feelings. The present invention is characterized in that, in an automatic air conditioning control device for a vehicle, a pollution detection threshold level is set based on an output signal of an air pollution sensor so as to be larger than the sensor output signal by a certain value;
The contamination detection threshold level has at least an upper limit with respect to a change in the sensor output signal, and is set within a range of change whose lower limit is the lowest level of the sensor output signal at normal temperature, and the contamination detection threshold level is changed within the above change range at an arbitrarily determined rate of change that cannot be detected by the human sense of smell, and the sensor output signal is changed based on the change in the rate of change of the sensor output signal. The problem lies in that it is determined that a contamination state exists only when the contamination detection threshold level is exceeded. Embodiments of the present invention will be described below based on the accompanying drawings. First, the principle of the air pollution detection method according to the present invention will be outlined. An object of the present invention is to provide an automatic air conditioning control system for a vehicle that has standards for determining contamination that are similar to human feelings. In order to realize such an air conditioning control device, we will focus on the following pollution conditions and human olfactory characteristics. (1) The concentration of exhaust gas inside and outside the vehicle, the amount of cigarette smoke, etc. change relatively rapidly. (2) The human sense of smell cannot detect air pollution that changes slowly.
Also, your sense of smell gradually adapts, so you no longer find it unpleasant. That is, there is a range within which the human sense of smell can become accustomed to smells under certain temperature and humidity conditions. (3) With respect to the above range that one can get used to, there is a range above the upper limit where the odor is always felt as unpleasant, and a range below the lower limit where the odor is not felt. Therefore, considering the above properties (1) and (2), a gradual change in sensor output that cannot be detected by the human sense of smell is not judged to be "contaminated", but is detected by the human sense of smell. Adopting the principle that only sudden changes in sensor output are judged as ``contaminated'',
This is used to detect contamination. Also, the above properties (2) and (3)
In consideration of this, the above detection method is performed only within a certain range that has an upper limit and a lower limit that can be used. Next, a description will be given based on a specific example. FIG. 1 shows a block diagram of an air conditioning control device. 1 is a computer forming a control circuit. On the input side of the computer 1, an outside air gas sensor 2 mainly for detecting exhaust gas and an inside air gas sensor 3 mainly for detecting cigarette smoke are provided. is input into the computer 1. On the output side of the computer 1, there is a blower 6 in a duct 5 that forms an air flow path disposed inside the vehicle, and an outside air intake blower 6 formed in a bifurcated shape on the upstream side of the duct 5 as controlled objects. There is a switching damper 9 provided at the confluence of the duct 7 and the inside air intake duct 8, and the motor 6a of the blower 6 and the actuator 10 of the damper 9,
A drive control signal is output from the computer 1 via a damper drive circuit 11 and a blower drive circuit 12, respectively. In addition, as a gas sensor that detects cigarette smoke, electrodes are connected to a metal oxide semiconductor element whose main component is SnO ₂ whose resistance value changes due to adsorption and desorption of smoke, and the output voltage is measured. Possible examples include semiconductor gas sensors that detect smoke concentration and photoelectric gas sensors that utilize the fact that the amount of light received by a light-receiving element that receives light emitted from a light-emitting element changes depending on the smoke concentration. According to the above configuration, the computer 1 performs necessary signal processing based on the contamination information from the gas sensors 2 and 3, and the damper 9,
The blower 6 is operated appropriately, and air conditioning control such as outside air introduction, ventilation, and inside air circulation is automatically performed depending on the state of contamination inside and outside the vehicle interior. In the above signal processing,
Based on the sensing outputs of the gas sensors 2 and 3, it is determined whether or not the air inside and outside the vehicle interior is contaminated, thereby implementing the air pollution detection method according to the present invention. Next, the output characteristics of the gas sensors 2 and 3 and the air pollution detection method will be explained. The following is an example of a gas sensor 3 that detects the concentration of cigarette smoke for indoor use.
Let's talk about. FIG. 2 shows an example of a change in the output of the gas sensor 3 over time. The output of the gas sensor 3 outputs an analog signal such as a voltage depending on the concentration of cigarette smoke inside the vehicle.In this case, as the degree of pollution gradually increases, the sensor output 3 gradually increases in proportion to the degree of pollution. Rise. On the other hand, for such a sensor output a, the cigarette smoke concentration is larger than the sensor output by a certain value and changes at a rate of change that is undetectable to the human sense of smell as the sensor output changes. A detection threshold level b is set. This threshold level b is created within the computer 1, and changes as described above only between the upper limit value a ₁ and the lower limit value a ₂ which are predetermined due to the characteristics.
Then, when the sensor output a is below the lower limit value _a2 or above the upper limit value, the threshold level b is set to a constant value such that the lower limit value _a2 or the upper limit value _a1 is taken. Set. Here, the meaning of setting the upper limit value a ₁ and the lower limit value a ₂ and how to set them will be explained based on FIG. In Figure 3, the horizontal axis is temperature and humidity, the vertical axis is sensor output voltage, and _a3 indicates the limit line at which cigarette smoke concentrations higher than this will cause discomfort, and the environmental standard value is usually adopted. , on the other hand, _a4 indicates the limit line below which no odor is felt at low contaminant concentrations. The range c defined by such limit lines a ₃ and a ₄
is the range within which the human sense of smell can adapt and become accustomed to air pollution. The reason why the horizontal axis in Fig. 3 is temperature and humidity is because the sensor output a changes depending on the temperature and humidity.
When temperature is plotted on the horizontal axis and humidity is varied between 0 and 100%, the sensor output a fluctuates within a predetermined range. Therefore, in order to express the sensor output voltage in consideration of changes in temperature and humidity, the horizontal axis is expressed as temperature and humidity for convenience. In the above, when the sensor output falls above the limit line a ₃ , it can be determined that there is air pollution regardless of the state of change in the sensor output, while on the other hand, when the sensor output falls below the limit line a ₄ , the sensor It can be determined that the air is clean regardless of the state of change in output. Further, in the range c in which the user can get used to it, it becomes necessary to judge the state of air pollution according to the changing state of the sensor output. From the above, the upper limit a ₁ of the follow-up change range d of the threshold level b is the sensor output voltage a ₃ in the normal temperature range e corresponding to the environmental standard air pollution concentration, and the lower limit a ₂ is the sensor output voltage _a4 in the normal temperature range e, which corresponds to the cigarette smoke concentration that cannot be detected by the human sense of smell unless it changes to this extent. Then, the intermediate range c, in which the user can get used to it, is set as the follow-up change range d of the threshold level b. However, as is clear from FIG. 3, the above-mentioned range c in which the user can get used to it changes due to the influence of temperature and humidity. Therefore, in this range c that you can get used to, the normal temperature e
The following variation range d is set to the lowest level of the sensor output voltage. By doing so, it is possible to achieve at least the purpose of always determining that air pollution is contaminated when it exceeds the environmental standard value. Note that as shown in FIG. 4, the sensor output voltage characteristic 13 may have a steep slope due to the influence of temperature and humidity, but in such cases, the slope can be offset by a temperature compensation thermistor. It is necessary to correct the characteristics so as to approximate the characteristics shown in FIG. Therefore, regarding the change in the sensor output a in the follow-up change range d of the threshold level b, which is a range that can be used to, which is set by the lower limit value _a2 and the upper limit value _a1 , when the change is slow. Since the change in the threshold level b also follows the change in the sensor output by a certain value larger than the sensor output a, and in this case, the sensor output does not exceed the threshold level, The air inside the vehicle is determined to be clean. On the other hand, if the sensor output a suddenly changes and the change in the threshold level b cannot follow this change, the sensor output exceeds the threshold level and it is determined that the air inside the vehicle is contaminated. This judgment method is similar to the olfactory characteristics of humans. When the sensor output a changes to the upper limit value a ₁ or more, the threshold level b
is a constant upper limit value a ₁ , so it is determined that it is always contaminated, and when the sensor output a changes below the lower limit value a ₂ , the threshold level b is a constant lower limit value.
Since it is a ₂ , it is always judged to be clean. The tracking change range d is divided into, for example, 115 steps, and when the sensor output a changes slowly in the range d, the threshold level b is set to the sensor with a certain detection margin f of, for example, 25 steps. It is made to change following the output a. Therefore, inside the computer 1, arithmetic processing is performed to change the threshold level b while checking changes in the sensor output a of the gas sensor 3. Although the gas sensor 3 that detects the level of cigarette smoke concentration in the air inside the vehicle has been described above, the same applies to the air pollution detection method related to the gas sensor 2 that detects the level of pollution in the air outside the vehicle. As described above, it is determined whether the air inside and outside the vehicle is clean or dirty, and based on the determination whether the air is clean or dirty inside or outside the vehicle interior, one of the outside air introduction, ventilation, or inside air circulation in the air conditioner is selected. will be done. FIG. 5 is a flowchart relating to the above-described air conditioning control executed within the computer 1. In the air conditioning control device according to the present invention, in process 14, the contamination state of the inside air and outside air in the vehicle is determined by the above-described detection method, and in process 15, the contents of the current output memory storing the control mode are outputted and the current output is output. A main routine A executes necessary control corresponding to the contents of the memory, a subroutine B changes the threshold level, and a delay time is set depending on how the contamination state of the inside and outside air changes. It has a control program consisting of a subroutine D for. The main routine A is repeatedly executed, for example, every 0.2 seconds, and based on the decision 16, the subroutine B is activated every 15 seconds, for example, to check the threshold level. Furthermore, the subroutine D for setting the delay time is configured to be executed only when the determination of the pollution state is different between the previous state and the new state as a result of the process 14 related to the determination of the inside and outside air pollution state ( Judgment 17). In the main routine A, first, in initial setting 18, after the output of the sensor becomes stable, an initial threshold level is set and a threshold level change timer is set. The threshold level change timer is set to 15 seconds, for example, so that the threshold level is checked and changed every 15 seconds in subroutine B in response to changes in the sensor output signal as described above. Next, in process 19, the outputs of the sensors 2 and 3 are read, and in process 20, the data related to the sensor outputs are integrated. Thereafter, if the process does not proceed to subroutine B, the degree of contamination of inside air and outside air is immediately determined separately based on the air contamination detection method described above, and a control mode is thereby selected (process 14). Combinations of contamination states of inside air and outside air and control modes correspond as shown in the following table.

[Table] The control mode determined as described above is stored in the next output memory. If the control mode of the contents of the current output memory is equal to the control mode of the contents of the next output memory, the contents of the current output memory are output in process 15, and the damper 9 and blower 6
will be controlled. Subroutine B for changing threshold level b is executed after data integration (process 20) has been performed for 15 seconds (decision 16). First, the average value of the sensor output signal for 15 seconds is calculated using the following equation. Average value = Addition value of sensor output / Number of additions Then, take the difference between the above average value and the threshold level at that time, and if the difference is smaller than the detection margin f, increase the threshold level by one step, for example. (Process 21), when it is equal to the detection margin f, the current level is maintained (Process 22), and when it is greater than the detection margin f, the threshold level is lowered by, for example, one step (Process 23), and the threshold level b is changed. That's what I do. The amount by which the threshold level is changed is not limited to one step as described above, but can be set arbitrarily. However, this rate of change is determined to be constant and at a level that cannot be detected by the human sense of smell. Thereafter, it is determined whether or not the changed threshold level b is within the range d (judgment 24), and if it is within the range d, the process directly moves to process 25, where the threshold level change timer is reset, When it is outside the range d, the upper limit value _a1 or the lower limit value _a2 is set as the threshold level (process 26), and then the threshold level change timer is reset. In this way, the threshold level b is checked every 15 seconds, and by executing subroutine B, the range d is checked as described above.
Within range a, threshold level b follows changes in sensor output signal a at a constant rate of change, and outside range a, it is set to upper limit value a ₁ or lower limit value a ₂ . Therefore, in FIG. 2, if the sensor output a changes slowly, the threshold level b can be followed while maintaining the detection margin f (areas F and H). , when the sensor output a changes rapidly, it cannot be followed immediately (area G). As a result, the air in areas F and H is determined to be clean, and in area G, the sensor output a exceeds the threshold level b, and the air is determined to be dirty. Also, area I is always determined to be dirty, and area E is generally determined to be clean, but if the sensor output a rises to fall within range d as shown in the figure, it is determined to be dirty. A determination will be made. Next, subroutine D for setting the delay time
Regarding the above, if the determination of the contamination state regarding the inside air and outside air determined by process 14 is different from the contamination state in the previous determination, it is necessary to take a control mode corresponding to the new contamination state. , a certain delay time is set before executing a new control mode. Specific examples (some of them) are shown in the table below.

[Table] Therefore, according to the above table, if the judgment of the contamination state of inside air and outside air is different, the control mode is determined for the new judgment, but the method of change from the previous state to the new state is A delay time N is set in the delay timer T correspondingly. Such a program is executed in subroutine D. After the delay time N is set in the delay timer T, the main routine is repeated, during which time the contents of the next output memory are transferred to the contents of the current output memory on the condition that the delay timer T becomes 0, After that, a new control mode will be executed by process 15 (judgment
27, 28, processing 29, 30). However, if a new contamination state is determined again during execution of the above main routine, subroutine D is executed via judgment 17, a control mode corresponding to the new contamination state is determined, and a change in the contamination state is determined. The corresponding delay time N will be set in the timer memory again. The reason for setting the delay time as above is the process 14.
This is to provide time for confirming that the determination made by the above is reliable. As is clear from the above embodiments, the present invention detects the pollution state of the air inside and outside the vehicle interior, and automatically controls the air conditioner in accordance with the pollution state. By adopting the principle (3), we have made it possible to detect contamination using the same feeling as humans. As is clear from the above description, according to the present invention,
The contamination detection threshold level is less affected by rapid sensor output value fluctuations, making it possible to obtain air pollution judgments that are close to the human olfactory feeling, making it possible to improve vehicle comfort and the environment. Summer.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the air conditioning control system;
The figure is a graph showing the characteristics of gas sensor output changes and threshold level changes. Figure 3 is a graph showing the characteristics of the sensor output depending on temperature and humidity. Figure 4 is the same as Figure 3 for other sensors. Figure 5 shows contamination detection.
It is a flowchart diagram concerning air conditioning control. In the drawings, 1 is a computer, 2 is an outside air gas sensor, 3 is an inside air gas sensor, 6 is a blower, 9 is a damper, A is a main routine, B is a subroutine for changing a threshold level, D is a subroutine for setting a delay time, and a is a subroutine for setting a delay time. In the sensor output signal, b is the contamination detection threshold level, a ₁ is the upper limit value, and a ₂ is the lower limit value.

Claims (1)

[Claims] 1. In an automatic air conditioning control device for a vehicle, a pollution detection threshold level is set based on the output signal of an air pollution sensor so as to be larger than the sensor output signal by a certain value, and the pollution detection threshold level is The change range of the sensor output signal is set to have at least an upper limit, and the lower limit is the lowest level of the sensor output signal at the normal temperature, and the contamination detection threshold level is set to a change range that has at least an upper limit, and the contamination detection threshold level is The sensor output signal is changed to follow the sensor output signal at an arbitrarily determined rate of change that cannot be detected by the person's sense of smell, and it is determined that there is a contamination state only when the sensor output signal exceeds the contamination detection threshold level. A method for detecting air pollution in an automatic air conditioning control device for a vehicle, characterized in that: