JPH0693829A - Exhaust gas purifying device for internal combustion engine - Google Patents

Abstract

PURPOSE:To monitor the adsorption and desorption of unburnt components such as HC in an adsorbing device for adsorbing the unburnt components. CONSTITUTION:Concentration of HC at inlet and outlet sides of an adsorbing device A provided in an exhaust bypass passage, by means of sensors B, C, and a flow rate of exhaust gas passing through the adsorbing device A is detected. Further, a quantity of HC adsorbed by the adsorbing device is computed in accordance with the concentrations of HC at the inlet and outlet sides, and the flow rate of the exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device for an internal combustion engine, and more particularly to a device provided with an adsorption device for adsorbing unburned components such as HC.

[0002]

2. Description of the Related Art The following is a conventional example of this type of exhaust gas purifying apparatus for an internal combustion engine (Actual No. Sho 63-687).
(See Japanese Patent No. 13). That is, the exhaust passage in which the three-way catalyst device is interposed is branched upstream of the three-way catalyst device to form a bypass passage, and the adsorption device is interposed in this bypass passage.

In an operating region where the exhaust gas temperature is low, the exhaust gas is passed through the bypass passage to adsorb and collect unburned components such as HC in the exhaust gas by the adsorbing device, and then the exhaust gas is introduced into the three-way catalyst device. Further, in the operating region where the exhaust gas temperature is high, the exhaust gas is introduced into the three-way catalyst device without flowing through the adsorption device.

[0004]

By the way, self-diagnosis and H
Although it is necessary to monitor the state of desorption and adsorption of C, the above-mentioned measures have not been taken in the conventional example. The present invention has been made in view of such a situation, and an object thereof is to enable monitoring of the adsorption and desorption states of unburned components such as HC.

[0005]

Therefore, the present invention is based on FIG.
As shown in Fig. 3, an adsorption device A for adsorbing unburned components in exhaust gas
The first concentration detecting means B for detecting the concentration of unburned components in the exhaust gas at the inlet, the second concentration detection means C for detecting the concentration of unburned components in the exhaust gas at the outlet of the adsorption device A, and the passage through the adsorption device A The exhaust flow rate detection means D for detecting the exhaust flow rate, and the unburned component amount adsorbed in the adsorbing device A are calculated based on the detected inlet side unburned component concentration, outlet side unburned component concentration and exhaust flow rate. The adsorption amount calculating means E for

[0006]

In this way, the amount of unburned components adsorbed in the adsorbing device is calculated based on the unburned component concentration on the inlet side and the outlet side of the adsorbing device and the exhaust flow rate, and thus the unburned component of the adsorbing device is calculated. It has become possible to monitor the adsorption and desorption status.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 2 to 5 show a first embodiment of the present invention. Figure 2
In the exhaust passage 2 of the engine 1, a three-way catalyst device (not shown) is interposed, and the exhaust passage is branched upstream of the three-way catalyst device and then merged to form a bypass passage 3. An adsorption device 4 that adsorbs and collects HC in the exhaust gas is interposed in the bypass passage. The adsorption device 4
A first exhaust switching valve 5 is provided in the upstream bypass passage 3, and a second exhaust switching valve 6 is provided in the exhaust passage 2 downstream of the branch portion with the bypass passage 3. These first and second
The exhaust switching valves 5 and 6 are controlled to be opened / closed by a control device 7 which is a suction amount calculation means such as a microcomputer.

The bypass passage 3 upstream of the adsorption device 4 is provided with a first HC concentration sensor 8 as a first concentration detecting means for detecting the concentration of HC1 in the exhaust gas, and the bypass passage 3 downstream of the adsorption device 4 is provided with a second concentration. A second HC concentration sensor 9 as a detecting means is provided, and detection signals of these sensors 8 and 9 are input to the control device 7. In addition, the control device 7
Includes an air flow meter 10 as an exhaust flow rate detecting means.
The intake air amount detection signal from the water temperature sensor 11 and the cooling water temperature detection signal from the water temperature sensor 11 are input.

The control device 7 operates according to the flow chart of FIG. 3 to operate the indicator 12. Next, the operation will be described with reference to the flowchart of FIG. This routine is executed in time synchronization, for example, every 0.5 seconds. In S1, the detection signals of the intake air amount and the cooling water temperature are read.

In S2, the opening degree of the first exhaust switching valve 5 is detected from the map based on the detected cooling water temperature, and the opening degree of the first exhaust switching valve 5 is controlled so as to reach this search value.
As shown in FIG. 4, the opening degree of the first exhaust switching valve 5 is fully opened to adsorb HC at a cooling water temperature of 50 ° C. or lower, and desorbs HC at a cooling water temperature of 80 ° C. or higher. It is set to be fully opened. Further, as shown in FIG. 4, the opening is fully opened when the cooling water temperature is in the range of 60 ° C. to 75 ° C., and still another temperature region (50 ° C. to 60 ° C., 75
(° C to 80 ° C), it is set to have an intermediate opening degree according to the cooling water temperature.

In step S3, the opening of the second exhaust switching valve 6 is detected from the map based on the detected cooling water temperature, and the opening of the second exhaust switching valve 6 is controlled so as to reach this search value.
As shown in FIG. 5, the opening of the second exhaust switching valve 6 is fully opened to allow the exhaust gas to flow through the bypass passage 3 for adsorbing HC when the cooling water temperature is 50 ° C. or lower, and when the cooling water temperature is 60 ° C. or higher. Fully open the exhaust gas to flow through the exhaust passage 2, 50 ℃
In the range of from 60 ° C. to 60 ° C., the intermediate opening degree is set according to the cooling water temperature.

At S4, the opening TVO retrieved at S2
Based on 1, the bore opening area S1 of the first exhaust switching valve 5 is calculated by the following equation. S1 = π (R1) ² (1-COSTVO1) R1 is the bore radius of the first exhaust switching valve 5. In S5, the second exhaust switching valve 6 is opened based on the opening TVO2 detected in S3.
The bore opening area S2 of is calculated by the following equation.

S2 = π (R2) ² (1-COSTVO2)
R2 is a bore radius of the second exhaust switching valve 6. S6
Then, from the detection signal of the first HC concentration sensor 8, the adsorption device 4
The HC concentration HC1 on the inlet side of is read. In S7, the second HC
The HC concentration HC2 on the outlet side of the adsorption device 4 is read from the detection signal of the concentration sensor 9.

In step S8, the routine proceeds to 0. of the routine based on the bore opening areas S1 and S2 calculated in steps S4 and S5, the inlet and outlet HC concentrations HC1 and HC2, and the detected intake air amount Q. The adsorbed HC weight MHC adsorbed by the adsorption device 4 in 5 seconds is calculated by the following equation. MHC = K × Q × (HC1-HC2) × S1 / (S1 +
S2) K is a constant, which is a positive value when in the adsorption state,
It is set to a negative value in the detached state and to zero in the equilibrium state. Here, {Q × S1 / (S1 + S
2)} corresponds to the exhaust gas flow rate passing through the adsorption device 4.

In S9, the adsorbed HC weight MHC calculated in S8 is added to the total adsorbed HC weight TMHC calculated in the previous routine to obtain a new total adsorbed HC weight.
In S10, it is determined whether or not the ignition switch is ON. If YES, the process proceeds to S11, and if NO, S
Proceed to 12. In S11, the total adsorption H determined in S9
The C weight is displayed on the display device 12 to inform the driver of the HC adsorption amount. As a result, when the HC adsorption amount is large, H
The driver must drive at high speed (eg 40 km) to oxidize and remove C.
/ H) It is possible to encourage the driver to perform the above driving.

In S12, the total adsorbed HC weight is stored in the RAM as data for the next operation. As described above, the total adsorbed HC based on the HC concentration on the inlet side and the outlet side of the adsorption device 4 and the exhaust flow rate introduced into the adsorption device 4.
Since the weight is calculated and displayed on the display device 12, the driver can monitor the HC adsorption and desorption conditions of the adsorption device 4, and when the adsorption amount is large, the driver can operate at high speed (for example, 40 km / h). ) Can be surely reduced and the adsorbed amount can be surely reduced, and the exhaust gas measures in North America can also be dealt with.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the configuration of the following embodiments, the same elements as those of the first embodiment are designated by the same reference numerals as those of FIG. 2 and their description is omitted. Further, in the flow charts of the following embodiments, the same flow chart as that of the first embodiment is used. The same steps are denoted by the same step numbers as those in FIG. 3, and description thereof will be omitted.

In FIG. 6, an exhaust temperature sensor 21 for detecting the exhaust temperature is attached to the adsorption device 4, and the output signal of the exhaust temperature sensor 21 is input to the control device 22.
Then, in S21 of FIG. 7, the detection signals of the intake air amount and the exhaust temperature are read. In S22, the opening degree of the first exhaust gas switching valve 5 is searched from the map based on the detected exhaust gas temperature, and the opening degree of the first exhaust gas switching valve 5 is controlled so as to reach this search value. As shown in FIG. 8, the opening of the first exhaust switching valve 5 is fully opened to adsorb HC at an exhaust temperature of about 200 ° C. or lower, and desorbs HC at an exhaust temperature of about 300 ° C. or higher. It is set to be fully opened. Also,
As shown in FIG. 8, the opening degree is set to the minimum opening degree in the exhaust gas temperature range of about 220 ° C. to about 270 ° C., and is set to the intermediate opening degree according to the exhaust temperature in other temperature regions. .

In S23, the opening of the second exhaust switching valve 6 is searched from the map based on the detected exhaust temperature, and the opening of the second exhaust switching valve 6 is controlled so as to reach this search value. As shown in FIG. 9, the opening degree of the second exhaust switching valve 6 is fully closed to allow the exhaust gas to flow to the bypass passage 3 when the exhaust gas temperature is about 200 ° C. or less, and the exhaust gas temperature is about 220 to 2
It is fully opened at 30 ° C or higher, and is set to an intermediate temperature according to the exhaust temperature in other temperature regions.

Then, as in the first embodiment, S4 and S
In 5, the port opening areas of the first and second exhaust switching valves 5 and 6 are calculated, respectively, and the adsorbed HC weight is calculated in S8, and then the total adsorbed HC weight is calculated in S9.
Then, when the ignition switch is turned on, the display device 1
The total adsorbed HC weight is displayed in 2 (S11), and the total adsorbed HC weight is stored in the RAM when the ignition switch is turned off (S12).

In this embodiment as well, the same effect as in the first embodiment is obtained, and the exhaust temperature in the adsorption device 4 is detected to control the exhaust flow, so that the conditions for adsorbing and desorbing HC are set. Since it can be detected accurately, the adsorption and desorption of HC can be monitored more accurately than in the first embodiment. Next, a third embodiment of the present invention will be described with reference to FIGS.

In FIG. 10, an adsorbent temperature sensor 31 for detecting the adsorbent temperature is attached to the adsorber 4, and a detection signal of the adsorbent temperature sensor 31 is input to the controller 32. Then, in S31 of FIG. 11, the intake air amount,
Read the detection signal of the adsorbent temperature.

In S32, the opening of the first exhaust switching valve 5 is searched from the map based on the detected adsorbent temperature, and the opening of the first exhaust switching valve 5 is controlled so as to reach this search value. . As shown in FIG. 12, the opening of the first exhaust switching valve 5 is fully opened to adsorb HC at an adsorbent temperature of about 200 ° C. or lower, and desorbs HC at an adsorbent temperature of about 300 ° C. or higher. It is set to be fully open to do. Further, as shown in FIG. 12, the opening is such that the adsorbent temperature is about 220 ° C.
The minimum opening is set in the range of about 270 ° C., and in another temperature range, it is set to an intermediate temperature according to the adsorbent temperature.

Then, in S34, it is determined whether or not the detected adsorbent temperature is 400 ° C. or higher, and when YES, S3.
If NO in step 5, the process proceeds to step S8. Here, HC is oxidized in the adsorbent device 4 when the temperature of the adsorbent made of zeolite in which copper and palladium are ion-exchanged is 400 ° C. or higher. Therefore, when it is determined that the adsorbent temperature is 400 ° C. or higher, the adsorbed HC weight in this routine is set to zero in S35, and the process proceeds to S9. On the other hand, when the adsorbent temperature is lower than 400 ° C., the adsorbed HC weight in this routine is calculated in S8, and the process proceeds to S9. In S9, the total adsorbed HC weight is calculated based on the adsorbed HC weight obtained in S8 or S35. Then, when the ignition switch is turned on, the total adsorbed HC weight is displayed on the display device 12 (S11), and when the ignition switch is turned off, the total adsorbed HC weight is stored in the RAM (S12).

Also in this embodiment, in addition to the same effect as the first embodiment, the adsorbed HC weight is changed according to the adsorbent temperature, so that the total adsorbed HC weight can be accurately estimated, It is possible to improve the accuracy of monitoring the adsorption amount. Next, a fourth embodiment of the present invention will be described with reference to FIGS. 14 and 15. In the flowchart of FIG. 14, the same steps as those in the second embodiment are designated by the same step numbers as those in FIG. 7 and their description is omitted.

In this embodiment, as in the second embodiment, the exhaust gas temperature inside the adsorption device 4 is detected by the exhaust gas temperature sensor, and the exhaust gas temperature detected in S41 is 40%.
Whether the temperature is 0 ° C. or higher is determined. If YES, the process proceeds to S42, and if NO, the process proceeds to S45. Here, the exhaust temperature is 40
HC becomes oxidized in the adsorption device 4 when the temperature is 0 ° C. or higher.

When it is determined that the exhaust gas temperature is 400 ° C. or higher, 0.5 second is added to the count value of the timer in S42 to start or continue counting. In S43, the HC oxidation amount HC3 in the adsorption device 4 is searched from the map based on the count time of the timer. As shown in FIG. 15, the amount of HC oxidation in the adsorber 4 is designed to increase rapidly after the exhaust temperature reaches 400 ° C. and then gradually decrease with time.

In S44, the retrieved HC oxidation amount HC3
Based on, the adsorbed HC weight MHC in this routine
Is calculated by the following equation. MHC = K × Q × (HC1-HC3) × S1 / (S1 +
S2) K is a constant, Q is the intake air amount, HC1 is the inlet side concentration of the adsorption device 4, S1 is the bore opening area of the first exhaust switching valve 5, S2
Is the bore opening area of the second exhaust switching valve 6.

On the other hand, when it is determined that the exhaust temperature is less than 400 ° C., the count value of the timer is reset to the initial value (= 0) in S45, and then the process proceeds to S8, in which the HC concentration on the inlet side and the outlet side of the adsorption device 4 is set. Based on this, the adsorbed HC weight in this routine is calculated. Then, in S9, S
8 or the total adsorbed HC weight is calculated based on the adsorbed HC weight obtained in S44.

In this way, when the total amount of adsorbed HC is obtained by subtracting the amount of oxidized HC, the total amount of adsorbed HC may have a negative value. Therefore, in S46, it is determined whether the total adsorbed HC weight calculated in S9 is zero or more,
If YES, the process proceeds to S10 without passing through S47, and if NO, the total adsorbed HC weight is set to zero in S47 and then the process proceeds to S10.

Then, when the ignition switch is turned on, the total adsorbed HC weight is displayed on the display device 12 (S11), and when the ignition switch is turned off, the total adsorbed HC weight is stored in the RAM (S12). Also in this embodiment, the first
In addition to the effect similar to that of the embodiment, the HC oxidation amount to be oxidized in the adsorption device 4 is obtained, so that the total adsorbed HC weight can be obtained with higher accuracy, and thus the monitoring accuracy can be improved. .

[0032]

As described above, according to the present invention, the intake amount of the intake device is calculated based on the unburned component concentration on the inlet side and the outlet side of the adsorption device and the exhaust flow rate. It is possible to monitor the adsorption of unburned components,
The detached state can be judged.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is a configuration diagram showing a first embodiment of the present invention.

FIG. 3 is a flowchart of the above.

FIG. 4 is a characteristic diagram for explaining the operation of the above.

FIG. 5 is another characteristic diagram for explaining the operation of the above.

FIG. 6 is a configuration diagram showing a second embodiment of the present invention.

FIG. 7 is a flowchart of the above.

FIG. 8 is a characteristic diagram for explaining the operation of the above.

FIG. 9 is another characteristic diagram for explaining the operation of the above.

FIG. 10 is a configuration diagram showing a third embodiment of the present invention.

FIG. 11 is a flowchart of the above.

FIG. 12 is a characteristic diagram for explaining the operation of the above.

FIG. 13 is another characteristic diagram for explaining the operation of the same.

FIG. 14 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 15 is a characteristic diagram for explaining the operation of the above.

[Explanation of symbols]

 4 Adsorption device 7 Control device 8 1st HC concentration sensor 9 2nd HC concentration sensor 12 Indicator

Claims (1)

[Claims] 1. An exhaust gas purification device for an internal combustion engine, comprising an adsorption device for adsorbing unburned components in exhaust gas to an exhaust system of the engine,
First concentration detecting means for detecting the concentration of unburned component in the exhaust gas at the inlet of the adsorbing device, second concentration detecting means for detecting the concentration of unburnt component in the exhaust gas at the outlet of the adsorbing device, and passing through the adsorbing device Exhaust flow rate detecting means for detecting an exhaust flow rate, and an adsorption amount for calculating an unburned component amount adsorbed in the adsorption device based on the detected inlet side unburned component concentration, outlet side unburned component concentration and exhaust flow rate. An exhaust gas purifying apparatus for an internal combustion engine, comprising: an arithmetic unit.