JPH11148343A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an HC desorbing performance. SOLUTION: When HC is adsorbed to an adsorbent when water temperature TW is a specified value or higher, and adsorption flag FK is 1, an auxiliary- passage in which the adsorbent intervenes half opens (S10→S11→S12), and when the temperature TK of the adsorvent is not high enough to completely desorb HC, the presence or absence of a fuel-cutting signal is judged (S13→S14), if a fuel cutting signal is detected, an exhaust emission recirculating amount controlling valve, which intervenes in a passage recirculating exhaust emission containing desorbed HC, is completely opened (S15), and when fuel cutting signal is not detected, the exhaust emission recirculating amount controlling valve is controlled to the opening degree that is retrieved from a map from engine speed N and basic fuel injection amount Tp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine having an HC adsorbent, and more particularly to a technique for improving the efficiency of desorbing HC from the adsorbent.

[0002]

2. Description of the Related Art A conventional exhaust gas purifying apparatus for an internal combustion engine having an HC adsorbent is disclosed, for example, in Japanese Patent Application Laid-Open No. 7-91238. When the exhaust gas temperature is low immediately after starting the engine at a low temperature or the like, exhaust gas can hardly be purified by the exhaust gas purifying catalyst (three-way catalyst). Therefore, in the conventional example, the unburned fuel (HC) is converted to HC while the catalyst is not activated.
There has been proposed an exhaust gas purifying apparatus that temporarily traps the adsorbent, desorbs HC adsorbed after the catalyst is activated, returns the desorbed HC to the intake air, and purifies the exhausted HC with the activated catalyst.

[0003]

However, the conventional exhaust gas purifying apparatus for an internal combustion engine having an HC adsorbent has the following problems. That is, the exhaust gas containing the desorbed HC is returned to the intake air when the desorbed HC is purified, but the recirculation of the exhaust gas deteriorates the combustion of the engine. Therefore, the amount of exhaust gas recirculation is limited due to the stability of the engine, and a large amount of exhaust gas cannot be returned to the engine. Therefore, the amount of exhaust gas flowing to the adsorbent during HC desorption processing is limited to a small amount. As a result, it takes a long time to raise the temperature of the adsorbent to the HC desorption temperature, and it takes a long time for the total amount of desorbed HC to return to the intake air even when the HC desorption temperature is reached.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and it is possible to improve the desorption processing efficiency and to complete the desorption processing in a short time without deteriorating the stability of the engine. It is an object of the present invention to provide an exhaust gas purifying apparatus for an internal combustion engine.

[0005]

According to the first aspect of the present invention, a part of an exhaust passage is branched into a main passage and a sub-passage provided with an adsorbent for adsorbing unburned HC. adsorption·
While switching the exhaust flow in the main passage and the sub passage according to the desorption processing conditions, the exhaust gas containing HC desorbed from the adsorbent during the desorption process of HC is returned to the intake air, and the HC is inserted into the exhaust passage. In the exhaust gas purifying apparatus for an internal combustion engine, wherein the exhaust gas purifying process is performed by the exhaust gas purifying catalyst, the amount of recirculation of the exhaust gas containing the HC into the intake air is increased during the fuel cut during the HC desorption process. I do.

According to the first aspect of the present invention, at the time of the HC desorption process, the sub-passage is opened to exhaust the adsorbent to desorb the HC adsorbed by the adsorbent, and to remove the HC adsorbed by the adsorbent.
Is returned to the intake air, flows to the exhaust purification catalyst via the engine, and is purified by the catalyst. When fuel cut is performed during the HC desorption process, the amount of exhaust gas containing the desorbed HC to the intake air is increased.

[0007] When the exhaust gas recirculation amount is increased during fuel cut as described above, the amount of heat obtained by exchanging heat with the exhaust passage or the exhaust purification catalyst or the like without combustion increases due to the increase in the gas amount and the exhaust gas. The flow rate of the low-temperature fresh air is reduced by the recirculation of air. As a result, the amount of heat supplied to the adsorbent increases, the temperature of the adsorbent rises in a short time, the desorption of HC is promoted, and the desorption end time can be shortened. Can be completed.

Further, since combustion is not performed during fuel cut, deterioration of combustion due to exhaust gas recirculation does not cause deterioration of engine stability. Further, in the invention according to claim 2, as shown in FIG. 1, a part of the exhaust passage is branched into a main passage and a sub passage provided with an adsorbent for adsorbing unburned HC,
A passage switching means for switching an exhaust flow of the main passage and the sub passage in accordance with a condition of the HC adsorption / desorption processing; and an exhaust gas containing HC desorbed from the adsorbent during the HC desorption processing is returned to the intake air. In an exhaust gas purifying apparatus for an internal combustion engine, comprising: an exhaust gas recirculation means for purifying HC by an exhaust gas purification catalyst provided in an exhaust passage; a fuel cut detection means for detecting a fuel cut state; Sometimes, during fuel cut, a recirculation amount increasing control means for increasing the amount of recirculation of the exhaust gas containing HC to the intake air is provided.

According to the second aspect of the present invention, at the time of the HC desorption process, the sub-passage is opened by the passage switching means to flow exhaust gas to the adsorbent to desorb HC adsorbed by the adsorbent, and to recirculate exhaust gas. The exhaust gas containing the desorbed HC is returned to the intake air by the means, flows to the exhaust purification catalyst via the engine, and is purified by the catalyst.

When the fuel is cut during the HC desorption process, the amount of exhaust gas containing the desorbed HC to the intake air is increased by the recirculation amount increasing means.
As a result, the amount of heat supplied to the adsorbent is increased and the desorption of HC is promoted without deteriorating the stability of the engine. Since the time can be shortened, the desorption can be completed even with a short trip.

The invention according to claim 3 is characterized in that a part of the exhaust gas is caused to flow into the sub-passage during the HC desorption process. According to the invention according to claim 3, H
During the desorption process of C, the exhaust gas recirculation amount is increased by, for example, increasing the opening degree of a passage for recirculating exhaust gas containing desorbed HC to intake air during fuel cut while flowing a part of the exhaust gas into the sub-passage. Let it.

Further, the invention according to claim 4 is characterized in that at the time of the HC desorption processing, the amount of exhaust gas flowing into the sub-passage during the fuel cut is larger than that during the non-fuel cut. According to the fourth aspect of the present invention, at the time of HC desorption processing, a part of the exhaust gas flows through the sub-passage during the non-fuel cut while flowing through the sub-passage during the non-fuel cut compared to during the non-fuel cut. , The amount of recirculation of exhaust gas containing desorbed HC is increased.

The invention according to claim 5 is characterized in that during the HC desorption processing, the entire amount of exhaust gas is caused to flow into the sub-passage when the fuel is cut off. According to the fifth aspect of the present invention, the flow rate of the exhaust gas flowing through the sub-passage, that is, the adsorbent is maximized at the time of the HC desorption processing, and most of the exhaust gas circulates through the engine and the adsorbent to produce low-temperature fresh air gas. Substantially does not flow, the amount of heat supplied to the adsorbent can be maximized, and the desorption end time can be further reduced.

Further, the invention according to claim 6 is characterized in that during the desorption process of the HC, the fuel cut is forcibly performed at the time of deceleration. According to the sixth aspect of the present invention, the fuel cut is performed rapidly even when the fuel cut is performed without performing the fuel cut because the fuel is rapidly decelerated when the fuel cut is performed and a shock is felt. That is, even if the fuel cut is performed during such a deceleration, by increasing the exhaust gas recirculation amount, it is possible to suppress a sudden decrease in the amount of gas sucked into the engine, thereby increasing the opportunity for increasing the exhaust gas recirculation amount. The time can be further reduced.

Further, the invention according to claim 7 is characterized in that the temperature of the adsorbent is detected, and the condition for performing the HC adsorption treatment is determined based on the temperature of the adsorbent. According to the invention according to claim 7, adsorption can be performed when the temperature of the adsorbent is equal to or lower than the temperature at which HC can be adsorbed.

The invention according to claim 8 is characterized in that the temperature of the engine cooling water is detected and the condition for performing the HC desorption process is determined based on the temperature of the engine cooling water. Claim 8
According to the invention, it is possible to determine whether or not the exhaust gas purifying catalyst is activated and the condition for performing the HC desorption process is satisfied based on the engine cooling water temperature.

The invention according to claim 9 is characterized in that the temperature of the exhaust gas purification catalyst is detected and the condition for performing the HC desorption process is determined based on the temperature of the exhaust gas purification catalyst. According to the eighth aspect of the present invention, it is possible to determine whether or not the condition for activating the exhaust purification catalyst and performing the HC desorption process has been reached based on the temperature of the exhaust purification catalyst.

The invention according to claim 10 is characterized in that the temperature of the adsorbent is detected, and the end of the HC desorption process is determined based on the temperature of the adsorbent. According to the tenth aspect, when the temperature of the adsorbent is equal to or higher than the temperature at which HC is completely desorbed, it is possible to determine the time to end the desorption process.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of an exhaust gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a block diagram showing functions of respective units of the present embodiment. In the figure, an exhaust gas purification catalyst (three-way catalyst) 3 is provided in an exhaust passage 2 of an internal combustion engine 1, and an exhaust passage 2 downstream of the catalyst 3 is
It is branched and formed into a main passage 4 and a sub passage 6 in which an adsorbent 5 for adsorbing unburned HC is interposed. A first switching valve 7 and a second switching valve 8 as passage switching means for switching the flow of exhaust gas are mounted in each of the branch portion and the junction portion of the main passage 4 and the sub passage 6.

Further, an exhaust gas recirculation passage 11 branching from the downstream side of the adsorbent 5 of the sub-passage 6 and reaching the intake passage 10 downstream of the throttle valve 9 is formed. The exhaust gas recirculation passage 11 controls the amount of exhaust gas recirculation. An exhaust gas recirculation amount control valve 12 is provided. The adsorbent 5 is provided with a temperature sensor 13 for detecting the internal temperature of the adsorbent 5, and the control unit 14 determines the HC adsorption conditions and desorption conditions based on the temperature of the adsorbent 5 as described later. Further, based on the result of this determination, switching of the exhaust flow between the main passage 3 and the sub passage 4 and the amount of exhaust gas containing exhaust desorbed HC to the intake air are controlled.

A rotation speed sensor 15 for detecting the engine rotation speed, a water temperature sensor 16 for detecting the temperature of the engine cooling water, and a throttle sensor 17 for detecting the opening of the throttle valve 9 are provided. The control 14 also controls the exhaust gas recirculation amount depending on the operating state of the engine 1 detected by these sensors.

Further, the execution of fuel cut is controlled by the control unit 14. That is, signals from the vehicle speed sensor 18 and the idle switch 19 are input to the control unit 14 together with the rotation speed sensor 14, and when the accelerator is returned and the idle switch 19 is detected from OFF to ON, the control unit 14 rotates at a predetermined vehicle speed or higher and the predetermined rotation speed. Fuel cut during deceleration is executed under the condition that the speed is equal to or higher than the speed. When the vehicle speed or the engine rotation speed falls below the set value, fuel injection is restarted, and the execution of fuel cut is terminated.

Next, the operation will be described. FIG. 6 is a time chart for facilitating the understanding of the embodiment of the present invention. When the exhaust gas purification catalyst 3 is cold, such as when the engine is started, the catalyst is not activated and the exhaust gas cannot be purified.
Therefore, in this period, the auxiliary passage 6 is opened as the adsorption period, and the exhaust gas is caused to flow to the adsorbent 5 to adsorb unburned HC to the adsorbent 5.

When the temperature Tk of the adsorbent 5 is Kk (for example, 200
(° C), it is determined that adsorption is possible, and the entire amount of exhaust gas is allowed to flow through the adsorbent 5. Next, if the temperature becomes higher than this temperature, the adsorbed HC will be desorbed. Therefore, the exhaust gas is not allowed to flow to the adsorbent 5, and the system waits in this state until the exhaust purification catalyst 3 is activated. If it is determined that the exhaust gas purification catalyst 3 has been completely activated, the desorption process is permitted assuming that the catalyst 3 can purify the desorbed HC. The activation of the catalyst can be determined, for example, based on the fact that the cooling water temperature Tk of the engine has reached Kk. The method of the desorption treatment is such that a part of the exhaust gas flows into the adsorbent 5, and the entire amount of the exhaust gas flowing back to the intake air. The exhaust gas returned to the intake contains the desorbed HC, and passes through the engine 1 again and is purified by the catalyst 3. Since the flow rate of the exhaust gas flowing to the adsorbent 5, that is, the flow rate of the exhaust gas returned to the intake air is limited by the stability of the engine,
This amount is controlled by the exhaust return / exhaust gas recirculation amount control valve 11, and is controlled so as not to affect the stability of the engine, for example, to a substantially constant ratio (for example, 10%) to the intake air amount.

To desorb HC adsorbed from the adsorbent 5, the temperature of the adsorbent 5 must be set to the HC desorption temperature (for example, 200 ° C. or higher). 5 is the complete desorption temperature (for example, 350 ° C or more)
However, in the above-described system, heat can be supplied only to the adsorbent 5 only by the fact that exhaust gas at a substantially constant rate flows into the adsorbent 5 with respect to the intake air amount of the engine. Could be. Therefore, during fuel cut during deceleration, the amount of exhaust gas recirculation is made large by maximizing the lift amount of the exhaust gas recirculation control valve, that is, a large amount of exhaust gas is flown to the adsorbent 5. Thereby, the temperature of the adsorbent 5 can be increased in a short time. During fuel cut, the exhaust gas temperature does not rise because fuel is not burned. Heat can be given to the adsorbent 5 as much as the exhaust gas flow rate is increased without decreasing substantially. Further, by recirculating a large amount of exhaust gas during fuel cut, the amount of fresh air gas (intake air amount) sucked into the engine at this time, that is, the amount of low-temperature gas is reduced, and there is also an effect that the exhaust gas temperature does not decrease.

When the fuel is cut, the first switching valve 7 on the upstream side is operated to flow the entire amount of exhaust gas to the adsorbent 5, and the entire amount is returned to the intake air. This effect is further enhanced (second embodiment). Form). Since the combustion is not performed in the engine at the time of fuel cut, the stability of the engine is not impaired no matter how much exhaust gas is recirculated to the intake air, so that the above-mentioned system becomes possible.

As a method of increasing this effect,
There is also a method of forcibly performing a fuel cut for deceleration without performing a normal fuel cut (third embodiment). This is to monitor the opening of the throttle valve 9 and forcibly perform a fuel cut when it is determined that the vehicle is decelerating. Normally, forcible fuel cut will result in a sudden deceleration. However, in this system, a large amount of exhaust gas is recirculated together with the fuel cut, so that pump loss in the engine 1, that is, engine brake, is reduced. Therefore, even if the fuel cut is forcibly performed, there is no sudden deceleration, and there is no problem.

Next, the temperature T of the adsorbent 5 is
When k becomes equal to or higher than the complete desorption temperature Kd (for example, 350 ° C.), the first switching valve 7 and the second switching valve 8 are operated so that the entire amount of the exhaust gas flows into the main passage 4, and the exhaust gas is exhausted. The reflux control valve 12 is closed to end the desorption process. By using the above-described desorption processing method, the desorption processing time can be shortened and a short trip can be dealt with.

Further, since an additional system such as heating of the adsorbent with electricity to accelerate the desorption process is not required, the system can be simplified and the cost can be reduced. Next, a first embodiment will be described with reference to the flowcharts of FIGS. 3 and 4 show the adsorption process of HC. In step (denoted as S in the figure, the same applies hereinafter), at l, it is determined whether or not the exhaust gas purification catalyst 3 is activated based on the engine cooling water temperature (hereinafter referred to as water temperature) TW. The water temperature TW is equal to a predetermined value Kc (for example, 7
0 ° C) or less, it is determined that the catalyst 3 is not active, and the process proceeds to S2.

In step 2, it is determined from the adsorption flag FK whether the adsorbent 5 has been completely desorbed last time. When the adsorption flag FK is 0, the desorption process has been completed, indicating that HC can be adsorbed. When the flag FK is 1, it indicates that the desorption process has not been completed and the adsorbent 5 has adsorbed HC, and that the desorption process is necessary. If it is determined in step 2 that HC can be adsorbed, the process proceeds to step 3, and it is determined whether the temperature TK of the adsorbent 5 is a temperature at which adsorption is possible (Kk temperature or less: Kk is, for example, 200 ° C.).

If it is determined in step 3 that the temperature is such that it can be adsorbed, the process proceeds to step 4 where the first switching valve 7
The second switching valve 8 is driven to flow exhaust gas to the adsorbent 5,
Adsorb unburned HC in exhaust gas. At this time, the first switching valve 7 fully closes the main passage 4 side to allow the entire amount of exhaust gas to flow to the sub passage 6, and the second switching valve 8 fully closes the main passage 4 side to exhaust gas from the sub passage 6. Is returned to the main passage 4.

In step 5, an adsorption flag FK is set to 1 to indicate that HC has been adsorbed by the adsorbent 5. Next, the flow moves to the flow shown in FIG. On the other hand, the determinations in steps 1 to 3 are NO,
If it is determined that no exhaust gas is to flow, the process proceeds to step 6,
By driving the first switching valve 7 and the second switching valve 8, the auxiliary passage 6 is closed so that exhaust gas flows through the main passage 4, and the adsorbent 5
To prevent the exhaust gas from flowing, and terminate the adsorption flow. The flow up to this point is executed only once after starting.

Next, when proceeding to the above-mentioned flow, the following flow is executed. That is, in step 7, the activation of the exhaust gas purification catalyst 3 is determined based on the water temperature TW as in step 1, and in step 8, it is determined whether or not the adsorption is possible based on the temperature of the adsorbent 5 as in step 3. Until the activation or the temperature of the adsorbent 5 exceeds the adsorbable region, the current condition is maintained and the exhaust gas is continuously flown to the adsorbent 5 to adsorb HC. This flow is repeatedly executed every certain time, for example, in synchronization with the input of the reference crank angle signal ref.

In the meantime, if it is determined that the catalyst 3 has been activated, or if the temperature of the adsorbent 5 has exceeded the adsorbable range, the routine proceeds to step 9, where the first switching valve 7, the second switching valve 8 Is driven to open the main passage 4 and close the sub-passage 6, so that the exhaust gas is not flown into the adsorbent 5 to end the adsorption. When the suction process is completed in this way, this flow is not executed until the next start.

Next, the HC desorption process will be described with reference to the flowchart of FIG. In step 10, it is determined whether the water temperature TW is equal to or higher than the predetermined value Kc, that is, whether the catalyst 3 is activated and the HC desorption process can be performed. When it is determined that the catalyst 3 is activated when the water temperature TW is equal to or higher than the predetermined value Kc, the routine proceeds to step 11, where it is determined whether or not HC is adsorbed by the adsorbent 5, that is, whether or not desorption processing is necessary. Determined by

If it is determined in step 11 that the desorption processing is necessary (if the adsorption flag FK is 1), the flow proceeds to step 12 and on to perform the desorption processing. First, in step 12, the first switching valve 7 is half-opened in order to perform the desorption process, so that the exhaust gas flows through both the main passage 4 and the sub passage 6.
The second switching valve 8 keeps the sub passage 6 closed and the main passage 4 open.

In step 13, the temperature TK of the adsorbent 5 becomes H
It is determined whether or not C has reached a temperature Kd (for example, 350 ° C.) at which complete desorption occurs. If it is determined in step 13 that the temperature TK of the adsorbent 5 has not reached Kd, the routine proceeds to step 14, where it is determined whether or not the engine is currently being fuel cut. If it is determined in step 14 that the fuel is being cut, the process proceeds to step 15, where the exhaust gas recirculation amount control valve 12 is fully opened to increase the exhaust gas recirculation amount. That is, step
14 functions as fuel cut detection means,
15 functions as a reflux amount increase control means.

If it is determined in step 12 that the fuel is not being cut, the routine proceeds to step 16, where the engine speed N,
After reading the basic fuel injection amount Tp, in step 17, the opening degree of the exhaust gas recirculation amount control valve 12 is searched from a map (see FIG. 7) based on the engine speed N and the basic fuel injection amount Tp.
The exhaust gas recirculation amount control valve 12 is driven to have the opening. The flow up to this point is repeatedly executed every certain time, for example, in synchronization with the input of the reference crank angle signal ref.

On the other hand, the temperature T of the adsorbent 5
When it is determined that K is equal to or higher than the complete desorption temperature Rd, it is determined that the adsorbed HC has completely desorbed,
Allow the termination of the desorption process. In step 18, the desorption process is completed, the adsorption flag FK is set to 0 in order to store that HC is not adsorbed in the adsorbent 5, and step 1 is executed.
9. In step 20, the first switching valve 7 is driven to flow the entire amount of exhaust gas to the main passage 4 so that the exhaust gas does not flow to the adsorbent 5, and the exhaust gas recirculation amount control valve 12 is fully closed. The desorption process ends. Thus, all the flows are completed.

When the desorption process is completed in this way, this flow is not executed until the next start. Next, a second embodiment will be described. In the second embodiment, when the fuel is being cut during the HC desorption process, the exhaust gas recirculation amount control valve 12 is fully opened and the first switching valve 7 is driven to reduce the entire amount of exhaust gas to the adsorbent. Pour into 5,
This is a system that returns the whole amount to the intake air. By doing so, the amount of exhaust gas flowing to the adsorbent 5 can be further increased, and the entire amount of exhaust gas is recirculated, so that the amount of fresh air gas (intake air amount) sucked into the engine 1 during fuel cut. That is, the amount of low-temperature gas is completely eliminated, and the effect of not lowering the exhaust gas temperature is increased. Therefore, compared with the first embodiment, the desorption processing efficiency is further increased, the desorption end time is shortened, and a short trip can be dealt with.

FIG. 8 shows a flowchart of the HC desorption process according to the second embodiment. After step 15 in the flow chart of the desorption process in the first embodiment shown in FIG. 5, the first switching valve 7 is driven in step 21 so that the entire amount of exhaust gas flows into the adsorbent 5. is there. FIG. 9 shows a time chart according to the second embodiment. During the HC desorption process, the first switching valve 7 is driven to half open so that exhaust gas flows through both the main passage 4 and the sub-passage 6. If the fuel cut is executed during the desorption process, the first switching valve 7 is synchronized with this. The first switching valve 7 is controlled so that the side of the sub passage 6 is fully opened.

Next, a third embodiment will be described. In the third embodiment, the fuel cut is forcibly performed also in the deceleration in which the normal fuel cut is not performed. The fuel cut control will be described with reference to the flowchart of FIG. Steps
At step 31, the opening TVO of the throttle valve 9 is read.

In step 32, the throttle valve opening T
The amount of change ΔTVO per unit time of the VO is calculated. In step 33, it is determined whether or not the vehicle is decelerated based on whether or not the change amount ΔTVO is equal to or less than a negative predetermined value G. And
When it is determined in step 33 that the vehicle is decelerating, the routine proceeds to step 34, in which the fuel cut is forcibly performed. This flow is repeated every certain time, for example, in synchronization with the input of the reference crank angle signal ref.

As described above, during deceleration, including deceleration without fuel cut, the fuel cut is forcibly performed, so that the desorbing process of the adsorbent 5 can be further shortened. As described above, the present invention uses a desorption treatment method in which a large amount of exhaust gas is flown into the adsorbent and the whole amount is returned to the intake air during fuel cut in which the stability of the engine does not deteriorate even when a large amount of exhaust gas is recirculated. Thus, the desorption processing time can be shortened and a short trip can be handled.

In addition, since an additional system such as heating the adsorbent with electricity to accelerate the desorption process is not required, the system can be simplified and the cost can be reduced. Instead of determining the condition for performing (permitting) the desorption process based on the water temperature TW, a configuration may be adopted in which the temperature of the exhaust purification catalyst is detected and the determination is made based on the temperature of the catalyst.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration and functions of the invention according to claim 1;

FIG. 2 is a system diagram of an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention.

FIG. 3 is a first flowchart of an HC adsorption processing routine according to the first embodiment.

FIG. 4 is a second flowchart of an HC adsorption processing routine according to the first embodiment;

FIG. 5 is a flowchart of an HC desorption processing routine according to the first embodiment.

FIG. 6 is a time chart according to the first embodiment.

FIG. 7 is a map in which the opening degree of the exhaust gas recirculation amount control valve is set.

FIG. 8 is a flowchart of an HC desorption processing routine according to the second embodiment.

FIG. 9 is a time chart according to the second embodiment.

FIG. 10 is a flowchart of a fuel cut control routine according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust passage 3 Exhaust purification catalyst 4 Main passage 5 Adsorbent 6 Sub passage 7 First switching valve 8 Second switching valve 9 Throttle valve 10 Intake passage 11 Exhaust recirculation passage 12 Exhaust recirculation control valve 13 Temperature sensor 14 Control unit 15 Speed sensor 16 Water temperature sensor 17 Throttle sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 25/07 ZAB F02M 25/07 ZAB 550 550R (72) Inventor Hirofumi Tsuchida 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. Inside

Claims (10)

[Claims] A part of an exhaust passage is branched into a main passage and a sub-passage provided with an adsorbent for adsorbing unburned HC, and the main passage and the sub-passage are provided in accordance with the conditions for adsorbing and desorbing HC. An internal combustion engine that recirculates exhaust gas containing HC desorbed from the adsorbent to the intake air during the HC desorption process while switching the exhaust flow of the HC, and purifies the HC by an exhaust purification catalyst provided in the exhaust passage. In the exhaust gas purifying apparatus for an engine, at the time of the HC desorption processing, the fuel cut is performed during the fuel cut.
An exhaust gas purifying apparatus for an internal combustion engine, which increases an amount of recirculation of exhaust gas containing C to intake air. 2. A part of an exhaust passage is branched into a main passage and a sub-passage provided with an adsorbent for adsorbing unburned HC, and the main passage and the sub-passage are provided in accordance with the conditions for adsorbing and desorbing HC. A passage switching means for switching an exhaust flow of the exhaust gas, and an exhaust gas containing HC desorbed from the adsorbent during the desorption process of HC is returned to the intake air, and
An exhaust gas recirculation means for purifying C with an exhaust gas purification catalyst disposed in an exhaust passage, an exhaust gas purification device for an internal combustion engine, comprising: a fuel cut detection means for detecting a fuel cut state; Sometimes, during fuel cut, the H
A recirculation amount increasing control means for increasing an amount of recirculation of exhaust gas containing C to the intake air; and an exhaust gas purification device for an internal combustion engine. 3. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein a part of the exhaust gas is caused to flow through the auxiliary passage during the HC desorption process. 4. The fuel supply system according to claim 1, wherein the amount of exhaust gas flowing through the auxiliary passage during the fuel cut is larger than that during the non-fuel cut during the HC desorption process. An exhaust gas purification device for an internal combustion engine according to one of the above aspects. 5. An exhaust gas purifying apparatus for an internal combustion engine according to claim 4, wherein during the fuel desorption process, the entire amount of exhaust gas is caused to flow into the auxiliary passage during fuel cut. 6. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein a fuel cut is forcibly performed at the time of deceleration during the HC desorption process. 7. The method according to claim 1, wherein a temperature of the adsorbent is detected, and a condition for performing the HC adsorption process is determined based on a temperature of the adsorbent. An exhaust gas purification device for an internal combustion engine. 8. The engine cooling water temperature according to claim 1, wherein a temperature of the engine cooling water is detected and a condition for performing the HC desorption process is determined based on an engine cooling water temperature. Exhaust purification device for internal combustion engine. 9. A method for detecting the temperature of said exhaust gas purifying catalyst,
The exhaust gas purifying apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein a condition for performing the desorption process of C is determined based on a temperature of the exhaust gas purifying catalyst. 10. The method according to claim 1, wherein the temperature of the adsorbent is detected, and the end of the HC desorption process is determined based on the temperature of the adsorbent. An exhaust gas purification device for an internal combustion engine.