JP2850664B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, and more particularly, to an exhaust gas purifying apparatus for an internal combustion engine having an adsorbent for adsorbing hydrocarbon HC in exhaust gas in an exhaust passage.

[0002]

2. Description of the Related Art Conventionally, an adsorbent such as activated carbon is interposed in an exhaust passage of an engine, and at the time of a cold start in which the treatment function of a catalyst is deteriorated, HC is adsorbed by the adsorbent to remove HC to the atmosphere. There has been proposed a system in which the HC is treated with an activated catalyst at a high temperature at which diffusion is prevented and the adsorbent hardly performs an adsorption action.

[0003] As an example using an activated carbon adsorbent excellent in adsorption performance, there is a conventional one disclosed in, for example, Japanese Patent Application Laid-Open No. 62-255513. On the other hand, a conventional silencer generally has only a silencing function. However, as disclosed in Japanese Utility Model Publication No. 3-30573, a silencer is filled with a pellet-type catalyst to have a purifying function. Has also been proposed.

[0004]

In the exhaust gas purifying apparatus using the conventional activated carbon adsorbent, a canister for adsorbing the fuel vapor generated from the fuel tank is also used as the adsorbent. However, unburned oil components and carbon in the exhaust gas enter the canister, and the surface area of the activated carbon decreases, reducing the adsorption capacity. Therefore, there arises a problem that the HC purification performance cannot be obtained. In addition, since the degradation of the activated carbon is not considered, there is a problem that the introduction of the high-temperature exhaust gas accelerates the degradation of the activated carbon.

On the other hand, in the silencer which has a purifying function by filling the catalyst, the catalyst is in the silencer and the whole amount of exhaust gas always flows, so that the heat radiation is poor and the heat is maintained at a high temperature and the heat is deteriorated. There is a problem that is accelerated. The present invention
In view of such a conventional problem, the exhaust gas that has passed through at least a part of the muffler is adsorbed by an adsorbent, and adsorption and desorption are performed under predetermined conditions according to an engine operating state. It is another object of the present invention to provide an exhaust gas purifying apparatus for an internal combustion engine that has solved the above-mentioned various problems.

[0006]

The present invention provides an exhaust gas purifying catalyst and a silencer in an engine exhaust passage, adsorbs hydrocarbons in exhaust gas according to engine operating conditions, and desorbs adsorbed hydrocarbons. An exhaust gas purifying apparatus for an internal combustion engine having a material interposed therein, wherein a bypass passage having the adsorbent interposed is formed by branching from an exhaust passage downstream of a muffler, and the adsorbent is detected based on a detection of an engine operating state. Means for detecting the conditions for adsorbing hydrocarbons by the material, and path switching means for switching the bypass path and the exhaust path not passing through the adsorbent based on the detection result of the adsorption conditions to flow exhaust gas. And the means for detecting the adsorption condition comprises:
Stop the engine as a condition to shut off the passage from the exhaust passage.
Or, at the time of extremely low speed rotation or high speed rotation more than specified, specified
When the load is higher than the above, when the engine temperature is higher than
Either at the time of L-cut, misfire, or after a lapse of a predetermined time after starting
It is characterized by detecting any of the conditions .

Further, as shown in FIG. 1 (B), in a second exhaust gas purifying apparatus for an internal combustion engine according to the present invention, a bypass passage including the adsorbent is formed inside a muffler.
Means for detecting a condition for adsorbing hydrocarbons by the adsorbent based on detection of an engine operating state, and switching between the bypass passage and an exhaust passage not passing through the adsorbent based on a result of detection of the adsorbent to flow exhaust gas. It is configured to include a passage switching means.

In these apparatuses, the means for detecting the adsorption condition includes, for example, introducing exhaust gas into a bypass passage.
As the adsorption condition, it is only necessary to detect when the engine temperature is lower than or equal to a predetermined value and to detect a state where the bypass passage is not disconnected from the exhaust passage.

In these apparatuses, a means for detecting the temperature of the adsorbent as indicated by a chain line and a means for detecting the temperature of the adsorbent are used.
Means for shutting off the bypass passage from the exhaust passage when the temperature exceeds a predetermined temperature, and for circulating air through the bypass passage to desorb hydrocarbons adsorbed on the adsorbent. .

In these apparatuses, the adsorbent may be one containing, for example, activated carbon as an adsorbent.

[0011]

When the above various conditions are satisfied, it is determined that the exhaust gas should flow through the adsorbent to adsorb the hydrocarbon in the exhaust gas, and the bypass passage is switched to the open side. At this time, since the exhaust gas flows into the bypass passage after passing through at least a part of the muffler, after the unburned oil, carbon, and the like in the exhaust gas are removed by the muffler, the hydrocarbon reaches the adsorbent and the hydrocarbon is adsorbed. . Therefore, even when a material having a high adsorption performance such as activated carbon is contained as an adsorbent, the adsorption performance can be maintained well without being covered with unburned oil, carbon, or the like, and the adsorbent can be used at a high temperature where the adsorption capability is low. Under conditions where the exhaust gas is likely to be deteriorated due to exhaust heat even if it has an adsorption ability, the passage is switched so as not to allow exhaust gas to flow.

Further, since the desorbing of the hydrocarbon adsorbed on the adsorbent is carried out by blowing air in a state of being shut off from the exhaust passage, the desorbed hydrocarbon is not exposed to the exhaust at the time of desorption and is not burned with unburned oil or carbon. There is no pollution.

[0013]

Embodiments of the present invention will be described below. In FIG. 2 showing the system configuration of the embodiment, air is sucked into each cylinder of the V-type internal combustion engine 1 via an air cleaner 2, a throttle valve 3, and an intake manifold 4. Each of the branch portions of the intake manifold 4 is provided with an electromagnetic fuel injection valve 5.

The exhaust gas from the engine 1 is supplied to an exhaust manifold 6.
After being collected for each bank by a and 6b, they are guided to a muffler (silencer) 8 by exhaust pipes 7a and 7b, respectively. Three-way catalysts 9a and 9b are interposed in the exhaust pipes 7a and 7b, respectively, as exhaust purification catalysts. The control unit 10 incorporates a microcomputer, calculates a fuel injection amount Ti by the fuel injection valve 5 based on detection signals from various sensors as described later, and controls the fuel injection valve 5 based on the fuel injection amount Ti. By performing the opening drive control, the fuel supply to the engine 1 is electronically controlled.

The various sensors include a throttle valve 3
An air flow meter 11 for detecting an intake air amount Qa of the engine 1 upstream of the engine 1, a crank angle sensor 12 for extracting a rotation signal from a camshaft, a cooling water temperature sensor 13 for detecting a cooling water temperature Tw of the engine 1, an exhaust manifold 6a, Oxygen sensors 14a and 14b for detecting the oxygen concentration in the exhaust gas for each bank, a potentiometer type throttle sensor 15 for detecting the opening of the throttle valve 3, and outlets for the catalysts 9a and 9b. There are provided exhaust temperature sensors 16a and 16b for detecting exhaust temperature in the vicinity, an ignition switch 30, and a vehicle speed sensor 31 for detecting vehicle speed.

Reference numeral 17 denotes a control valve for adjusting the intake air amount during idling.
The amount of air supplied to the engine 1 through a bypass passage 18 provided to bypass the engine is adjusted. Further, a canister 19 for adsorbing fuel vapor from a fuel tank (not shown) is provided. Purge air from the canister 19 is controlled by a canister purge control valve 20, and is supplied to a downstream side of the throttle valve 3 via a purge passage 21. It is being introduced into the system.

The engine 1 of the present embodiment has the catalyst 9
The following configuration is provided as a system for adsorbing HC, which is to be discharged without being purified by a and 9b, to avoid discharge to the atmosphere. That is, on the downstream side of the muffler 8, the exhaust passage is branched into an exhaust main passage 22 and a bypass passage 23 that bypasses the exhaust main passage 22, and the bypass passage 23 provided to bypass the exhaust main passage 22 An adsorbent 24 for adsorbing hydrocarbons HC in the exhaust gas is interposed therebetween and is opened to the atmosphere.

As shown in FIG. 3, the adsorbent 24 is a base material (wash coat) held on a carrier 24a having a honeycomb structure.
Activated carbon 24c dispersed in 24b or JP-A-2-13
No. 5126, which is made of a material obtained by ion-exchange of a zeolite with a metal and has a high HC adsorption capacity at a low temperature, and desorbs HC adsorbed at a low temperature at a high temperature (for example, 200 ° C. or more). is there.

In the bypass passage 23 on the upstream side of the adsorbent 24, an electromagnetic first switching valve 25 is interposed.
A purge passage 26 is provided for communicating between the switching valve 25 and the adsorbent 24 and the purge passage 21. An adsorbent purge control valve 27 is interposed in the purge passage 26, and the HC desorbed from the adsorbent 24 flows downstream of the throttle valve 3 through the purge passage 26 and the purge passage 21 through the purge control valve 27. Is introduced into the intake system.

An electromagnetic second switching valve 28 is interposed in the exhaust main passage 22 downstream of the branch portion of the bypass passage 23. The adsorbent 24 has a floor temperature. An adsorbent temperature sensor 29 as an adsorbent temperature detecting means for detecting Ta
Is provided. Further, a third switching valve 32 is provided downstream of the adsorbent 24. The control unit 10 functions as an adsorption condition detecting means for detecting the condition of adsorption of HC by the adsorbent 24, and controls the valves 25, 27, 28 based on the detection result to control the adsorbent 24. Adsorption and adsorbent
It also has a function of controlling the introduction of HC desorbed from 24 into the intake system.

Here, the program will be described in detail with reference to the programs shown in the flowcharts of FIGS. This flow is executed every predetermined time (for example, 100 ms) during a predetermined time (for example, about 10 seconds) after the power is turned on (ignition ON) to the control unit and after the ignition is turned off. In the flowcharts of FIGS. 4 and 5, first, at P1, the ignition switch 30 is turned on and off.
F is read and ON / OFF discrimination is performed at P2. When it is determined that the ignition switch 30 is OFF, a timer Tm, which will be described later, is reset in P22.
Then, the second switching valve 28 is opened, and the first switching valve 25 and the third switching valve 32 are closed.

When it is determined that the ignition switch 30 is ON, the program proceeds to P3, in which the start switch 31
N and OFF are read, and ON and OFF are determined at P4. If it is determined that the start switch 31 is ON, that is, it is at the time of cranking, the timer Tm for measuring the elapsed time from the start of the start is started in P5, and the process proceeds to P6.

When it is determined that the start switch 31 has been turned off at P4 after the start is completed, a timer Tm is set at P20.
Is updated with a value obtained by adding a predetermined period (for example, 100 ms) at a time, and the count value Tm is increased by a predetermined time (for example, 100 s) at P21.
Is determined, and before reaching P6, the process proceeds to P6. P6
Then, the output of the crank angle sensor 12 is read to detect the engine speed N. Then, at P7, the engine speed N exceeds the set value close to stop, for example, exceeds 500 rpm, and the high speed set value 4000 rpm
It is determined whether it is within the range of less than the predetermined range. If it is determined that the value is out of the set range, the process proceeds to P18 and P19, where the second switching valve 28 is opened, and the first switching valve 25 and the third switching valve 32 are opened. close. That is, at the time of the stop and immediately before the stop, in order to prevent the emission of HC from the adsorbent 24 to the atmosphere, on the other hand, at high speed, the exhaust temperature is high and the exhaust gas flows through the adsorbent 24, and the adsorbent 24 may burn out. Therefore, the bypass passage 23 is closed and the exhaust main passage 22 side is opened to discharge the exhaust gas directly to the outside.

When it is determined that the engine speed N is within the above-mentioned set range, the program proceeds to P8, in which the cooling water temperature sensor
A cooling water temperature (hereinafter abbreviated as water temperature) Tw is detected from the output of 13, and the water temperature Tw is compared with a set temperature, for example, 60 ° C. at P9. When it is determined that the water temperature Tw exceeds the predetermined temperature of 60 ° C., the process proceeds to P23, 24, where the second switching valve 28 is opened and the throttles 25, 32 are closed, thereby directly discharging the exhaust from the exhaust main passage 22. Release to

When it is determined that the water temperature Tw is equal to or lower than the predetermined temperature of 60 ° C., the program proceeds to P10, where the intake air flow rate Q is detected from the output of the air flow meter 12, and at P11, the intake air flow rate Q and the crank angle sensor 12 are detected. The basic fuel injection amount T _P (= K · Q / N; K is a proportional constant) is calculated as a variable representing the engine load on the basis of the engine speed N detected by the output of (1).

[0026] Then, as compared with a set value 5ms the basic fuel injection quantity T _P at P12, when it is determined that T _P> 5ms is
Since the load is high and the exhaust temperature is high, it is determined that there is a possibility that the flow of exhaust gas may burn out the adsorbent 24 as in the case of high speed, and the process proceeds to P18 and P19 to discharge the exhaust gas directly to the outside. Also, P12
When it is determined that T _P ≦ 5 ms, the opening degree θa of the throttle valve 3 is detected from the output of the first throttle sensor 15a at P13,
After detecting the vehicle speed VSP from the output of the vehicle speed sensor 31 at P14, the process proceeds to P15, and whether the throttle valve 3 is fully closed and the fuel cut condition in which the vehicle speed VSP and the engine speed N are respectively equal to or more than predetermined values are satisfied. Determine whether or not. When it is determined that the fuel cut condition is satisfied, it is determined that the air concentration in the exhaust gas becomes excessively large by the fuel cut control, and the exhaust gas may flow through the adsorbent 24 to cause burnout. Proceed to, 19 and discharge exhaust gas directly to the outside.

If it is determined at P15 that the fuel cut condition is not satisfied, the routine proceeds to P16, where a misfire state is detected from a change in the output of the crank angle sensor 12, and the presence or absence of misfire is determined at P17. If it is determined in P17 that a misfire has occurred, the oxygen concentration in the exhaust gas becomes excessively large, so that the process proceeds to P18 and P19 and the exhaust gas is directly discharged to the outside. Also, P17
When it is determined in step S22 that no misfire has occurred, the first switching valve 25 and the third switching valve 32 are opened at P22, and the second switching valve 28 is closed at P23 to open the bypass passage 23 side. That is, the operating state obtained from the above conditions is a condition in which the condition that the adsorbent 24 can adsorb HC is satisfied and all the conditions that do not allow the exhaust gas to flow into the adsorbent 24 are excluded. Then, the bypass passage 23 is opened, the exhaust gas is circulated through the adsorbent 24, and the HC in the exhaust gas is
Is adsorbed.

In P21, a predetermined time (100
s) (T _m > 100 s), the three-way catalysts 9a, 9
b is determined to be activated by the temperature rise due to the exhaust heat, and P18, 19 to prevent the adsorbent 24 from being deteriorated by the exhaust heat.
To discharge the exhaust directly to the outside. Here, P1 to P17
And the functions of P20 and P21 correspond to the adsorption condition detecting means, and the first switching valve 25, the second switching valve 28, the third switching valve 32 and P1
The functions P8, P19 and P22, P23 correspond to the passage switching means.

Next, control of the desorption of HC from the adsorbent 24 will be described with reference to the flowchart of FIG. First,
In P31, the coolant temperature Tw is detected. In the next P32, the detected coolant temperature Tw exceeds a predetermined temperature (for example, 60 ° C.) at which activation of the three-way catalysts 9a and 9b is predicted. It is determined whether or not.

When the cooling water temperature Tw exceeds a predetermined temperature, the exhaust gas is satisfactorily purified by the catalysts 9a and 9b.
Since the amount of waste gas is sufficiently reduced, there is no need to adsorb by the adsorbent 24. Therefore, in this case, proceed to P33,
The second switching valve 28 is opened, and in the next P34, the first switching valve 25 is opened.
To prevent exhaust gas from being introduced into the bypass passage 23.

Next, at P35, the bed temperature Ta of the adsorbent 24 is detected by the adsorbent temperature sensor 29. Then, in P36, it is determined whether or not the detected bed temperature Ta of the adsorbent 24 exceeds a predetermined temperature (for example, 300 ° C.) at which there is a possibility that the adsorbent 24 may be burned out by the desorption control described later. Determine. Here, when the temperature of the adsorbent 24 does not exceed the predetermined burnout temperature, the process proceeds to P37, where the adsorbent purge control valve 27 and the third switching valve 32 are opened, and the bypass passage 23 is opened to the atmosphere by the suction negative pressure of the engine. The atmosphere is drawn from the end, and the desorbed HC is introduced into the intake system together with the atmosphere.

On the other hand, when the temperature of the adsorbent 24 exceeds the predetermined burnout temperature, when the fresh air passes through the adsorbent 24 due to the above-described drawing of the atmosphere, the temperature of the adsorbent 24 rises and the adsorbent 24 rises. Since there is a risk of burning the 24, proceed to P38, the adsorbent purge control valve 27 and the third switching valve 32
Is closed, and control for introducing the desorbed HC into the intake system together with fresh air is not performed.

On the other hand, if it is determined in P32 that the cooling water temperature Tw is lower than the predetermined temperature, the program proceeds to P39, where the bed temperature Ta of the adsorbent 24 is detected.
It is determined whether or not a exceeds the desorption temperature (for example, 200 ° C.). If the temperature exceeds the desorption temperature, the process proceeds to P33, in which the introduction of exhaust gas into the bypass passage 23 is shut off, and the purge control valve 27 is opened under a temperature condition in which there is no fear of burning of the adsorbent 24. The desorbed HC is introduced into the intake system.

When it is determined in P40 that the temperature of the adsorbent 24 has not reached the desorption temperature, the second switching valve 28 is closed in P41, and the first switching valve 25 and the third switching valve are closed in P42.
32 is opened, all exhaust gas is introduced into the adsorbent 24, and HC in the exhaust gas is adsorbed by the adsorbent 24. At this time, the process proceeds to P43, and the purge control valve 27 is maintained in a closed state.

The routine and the first switching valve 25, the second switching valve 28, the third switching valve 32, the purge passage 21 and the purge control valve 27 constitute a hydrocarbon desorbing means.
As described above, when the purge control valve 27 is controlled to be closed in accordance with the temperature condition of the adsorbent even in the desorption temperature state, the purge control valve 27 is operated under the temperature condition in which the adsorbent 24 desorbs. When the purge control valve 27 is controlled to be closed even though the first switching valve 25 is closed, the HC that has been desorbed by closing the third switching valve 32 is used.
To avoid being released into the atmosphere.

FIG. 7 shows a system configuration of an embodiment having a different desorption system. In this case, the present invention is applied to a device having a secondary air supply device for supplying secondary air into exhaust gas to purify HC and CO, and the discharge port of an air pump 41 as a secondary air supply source is connected to the adsorbent. The secondary air control valve 42 is connected to the bypass passage 23 between the first switching valve 25 and the third switching valve 32 and is provided downstream of the purge control valve 27 of the purge passage 26 branched from between the first switching valve 25 and the adsorbent 24. And the downstream end of the purge passage 26 is connected to the oxygen sensor 14a upstream of the three-way catalyst 9a.
It is configured to be connected to a more upstream exhaust manifold 6a. Alternatively, the downstream end of the same purge passage 26 is connected to the three-way catalyst 9b.
Exhaust manifold 6b upstream from upstream oxygen sensor 14b
Alternatively, the downstream end formed by branching the downstream end of the purge passage 21 may be connected to the exhaust manifolds 6a and 6b to supply the secondary air evenly.

In this case, when HC is to be desorbed, the same control as that shown in FIG. 5 may be performed, but the third switching valve 32 is closed, and the purge control valve 27 is opened to open the second control valve. HC is desorbed simultaneously with the supply of the next air. With this configuration, a part of the supply passage of the secondary air supply device can be shared, the size and cost can be reduced, and the contamination of the intake system by HC can be suppressed to a minimum.

Next, an embodiment in which a muffler (muffler) is provided with an adsorbent will be described. In FIG. 8 showing the system configuration of the present embodiment, one end is connected to the inlet side of the muffler 8 in parallel with the muffler 8 and the exhaust main passage 22 provided with the second switching valve 28 downstream of the muffler 8, and passes through the inside of the muffler 8. A first switching valve 25 is provided at an upstream end of the bypass passage 23 outside the muffler 8, and a muffler 8 is provided.
An adsorbent 24 is interposed in a portion located inside. The upstream end of the purge passage 21 is connected to a portion of the bypass passage 23 outside the muffler 8 and downstream of the first switching valve 25. Other configurations are the same as those shown in FIG. The components having the same function are denoted by the same reference numerals (the same applies to the following embodiments).

FIGS. 9A and 9B show the states of the suction operation and the desorption operation of the present embodiment, in which the first switching valve 25 is opened and the second switching valve is opened. By closing 28, opening the third switching valve 32, and closing the purge control valve 27, the exhaust main passage 22 and the purge passage 21 are closed, so that the exhaust gas that has passed through the muffler 8 flows out to the bypass passage 23, It is discharged to the outside of the muffler 8 through the adsorbent 24 inside the muffler 8. Further, at the time of desorption, the first switching valve 25 is closed, and the second switching valve 28,
By opening the third switching valve 32 and opening the purge control valve 27, the exhaust gas passes through the exhaust main passage 22 through the muffler 8.
While the air flows into the bypass passage 23 in a direction opposite to the exhaust gas flow direction at the time of adsorption,
C is desorbed and flows out to the purge passage 23.

As described above, at the time of adsorption, as in the above embodiment,
Since the exhaust gas that has passed through the muffler 8 flows into the adsorbent 24, the unburned oil and carbon in the exhaust gas are collected by the muffler 8, and the adsorption performance of the adsorbent 24 can be maintained well. As it is performed, it is not contaminated with unburned oil or carbon. Further, by making a part of the bypass passage 23 pass through the inside of the muffler 8, the compactness is promoted.

Further, by flowing exhaust gas through the adsorbent 24 only under the same adsorption conditions as in the above embodiment, deterioration of the adsorbent 24 due to exhaust heat can be suppressed. FIG. 10 shows an embodiment in which a part of the above embodiment is modified. The exhaust inlet of the bypass passage 23 is opened inside the muffler 8, and the first switching valve 25 and the adsorbent 24 interposed at the end of the inlet. The purge control valve is branched from the purge passage 21 so as to protrude outside the muffler 8.
(A) shows the state at the time of adsorption, and (B) shows the state at the time of desorption. 1st switching valve 25, 2nd switching valve 28, 3rd
Opening and closing of the switching valve 32 and the purge control valve 27,
The relationship with the desorption is the same as that of the above-described embodiment.
Adsorbent inside the muffler 8 without passing through the outside
Only at the point of flowing into the muffler 8, the compactness is further promoted by the increase in the ratio of the passage being accommodated in the muffler 8. , Functions and effects are the same.

FIG. 11 shows still another embodiment.
The exhaust inlet is opened inside the muffler 8 and the adsorbent 24 is
A first switching valve 25 is interposed in a downstream portion of the bypass passage 23 which is interposed in the inner portion of the
The purge passage 21 having a purge control valve 27 interposed is branched from the upstream portion of the first switching valve 25 and connected to the outside.

In this case, the time of adsorption shown in FIG.
The first switching valve 25 and the second switching valve 2 at the time of desorption shown in FIG.
8, the relationship between the opening and closing of the third switching valve 32 and the purge control valve 27 and the adsorption and desorption is the same as in the previous embodiment, and the adsorption function is the same. A part is led to the adsorbent 24 to desorb HC, and a purge passage
Differs in that it is discharged through 21. Further, the third switching valve 32 is not provided. However, muffler 8 is also used for desorption in the same manner as adsorption.
The exhaust gas that has passed through is guided to the adsorbent 24, so that contamination by unburned oil or carbon can be prevented.

Further, in the above-described embodiment in which the adsorbent is incorporated in the muffler, a configuration utilizing secondary air as the desorption means may be adopted.

[0045]

As described above, according to the present invention,
Since exhaust gas that has passed through at least a part of the silencer is guided to the adsorbent for adsorption, unburned oil and carbon in the exhaust gas can be removed by the silencer to prevent contamination of the adsorbent and improve adsorption performance. Since the exhaust gas can be maintained and the exhaust gas flows only when necessary, the thermal deterioration of the adsorbent material due to the exhaust gas can be suppressed as much as possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a schematic diagram showing a system configuration of a first embodiment.

FIG. 3 is a diagram showing a structure of an example of an adsorbent used in the embodiment.

FIG. 4 is a flowchart showing a suction control routine of the embodiment.

FIG. 5 is a flowchart following the above.

FIG. 6 is a flowchart showing a desorption control routine of the embodiment.

FIG. 7 is a schematic diagram showing a system configuration of a second embodiment.

FIG. 8 is a schematic diagram showing a system configuration of a third embodiment.

FIG. 9 is a cross-sectional view showing a state around the adsorbent during the adsorption operation and the desorption operation of the embodiment.

FIG. 10 is a cross-sectional view showing a state around the adsorbent during the adsorption operation and the desorption operation of the fourth embodiment.

FIG. 11 is a cross-sectional view showing the state around the adsorbent during the adsorption operation and the desorption operation of the fifth embodiment.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 5 fuel injection valve 8 muffler 9a, 9b three-way catalyst 10 control unit 11 air flow meter 12 crank angle sensor 13 cooling water temperature sensor 14a, 14b oxygen sensor 16a, 16b catalyst temperature sensor 19 canister 21 purge passage 22 exhaust main passage 23 Bypass passage 24 Adsorbent 25 First switching valve 26 Purge passage 27 Adsorbent purge control valve 28 Second switching valve 29 Adsorbent temperature sensor 32 Third switching valve

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 3/08-3/24

Claims (5)

(57) [Claims] An exhaust gas purifying catalyst and a silencer are provided in an engine exhaust passage, and an adsorbent for adsorbing hydrocarbons in exhaust gas and desorbing the adsorbed hydrocarbons according to engine operating conditions is interposed. An exhaust gas purification apparatus for an internal combustion engine, wherein a bypass passage interposed with the adsorbent is formed by branching off from an exhaust passage downstream of a muffler, and the hydrocarbon is adsorbed by the adsorbent based on detection of an engine operating state. Means for detecting the adsorption condition, and path switching means for switching the bypass path and the exhaust path not passing through the adsorbent based on the detection result of the adsorption condition to flow exhaust gas , and The means for detecting the adsorption condition includes a bypass passage.
As a condition to shut off the exhaust passage,
At low speed rotation or at higher speed than specified, high load more than specified
At load, when engine temperature is higher than specified, fuel cut
Hour, misfire, or any condition after a lapse of a predetermined time after starting
An exhaust gas purification device for an internal combustion engine, characterized by detecting the following . 2. An exhaust gas purifying catalyst and a silencer are provided in an engine exhaust passage, and an adsorbent for adsorbing hydrocarbons in exhaust gas and desorbing the adsorbed hydrocarbons according to engine operating conditions is interposed. An exhaust gas purification device for an internal combustion engine, wherein a bypass passage interposed with the adsorbent is formed inside a muffler, and a condition for adsorbing hydrocarbons by the adsorbent is detected based on detection of an engine operating state. Exhaust gas purification for an internal combustion engine, comprising: means for switching the bypass path and an exhaust path that does not pass through an adsorbent based on a detection result of an adsorption condition, and a path switching means for flowing exhaust gas. apparatus. 3. The adsorption condition detecting means detects, as an adsorption condition for introducing exhaust gas into the bypass passage, a time when the engine temperature is lower than a predetermined temperature or lower, and sets a condition in which the bypass passage is not disconnected from the exhaust passage. 請, characterized in that the detection
The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2 . 4. A means for detecting the temperature of the adsorbent, wherein when the temperature of the adsorbent exceeds a predetermined temperature, the bypass passage is cut off from the exhaust passage, and air is passed through the bypass passage to be adsorbed by the adsorbent. The exhaust gas purifying apparatus for an internal combustion engine according to any one of claims 1 to 3, comprising: means for desorbing a hydrocarbon. Wherein said adsorbent, the exhaust purification system of an internal combustion engine according to any one of claims 1 to 4 comprising the activated carbon as the adsorbent component.