JP2003314260A - Exhaust emission control device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device in which HC separated from an HC adsorption purifying means is purified at a prescribed purification ratio by the HC adsorption purifying means. <P>SOLUTION: The HC adsorption purifying means 14 has a function to adsorb HC when the temperature is low, and to separate and to purify the adsorbed HC when the temperature becomes high, and is arranged to an exhaust gas passage of the exhaust emission control device 20. The exhaust emission control device is provided with a bypass passage 18 to bypass the adsorption purifying means 14; and a flow rate control means 22 for controlling the flow rate of an exhaust gas to circulate the adsorption purifying means 14, by adjusting a ratio of the flow rate of the exhaust gas to circulate the adsorption purifying means 14 and the flow rate of the exhaust gas to flow the bypass passage 18. The exhaust emission control device is provided in which the flow rate of the exhaust gas to circulate the adsorption purifying means 14 is controlled by the flow rate control means 22, so as to be ≤ a predetermined upper limit flow rate for purifying the separated HC by the adsorption purifying means 14 at the prescribed purification ratio. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for purifying exhaust gas of an internal combustion engine, and more particularly, to an exhaust gas purifying device having an HC adsorbing and purifying means and an exhaust gas purifying method using the HC adsorbing and purifying means.

[0002]

2. Description of the Related Art Conventionally, as an apparatus and method for purifying HC (hydrocarbon) in exhaust gas discharged from an internal combustion engine, in addition to a three-way catalyst, an HC adsorption purification type catalyst is provided in an exhaust gas passage of the internal combustion engine. Those that are arranged are proposed. This HC adsorption purification type catalyst is one in which a precious metal such as platinum is supported on an HC adsorbent such as zeolite or silica, which adsorbs HC when the temperature is low and desorbs the adsorbed HC when the temperature is high. It has a function of purifying by an oxidation reaction as well as urging. In addition, when the temperature of the three-way catalyst becomes higher than the activation temperature and becomes active, the H
It has the function of purifying C. Therefore, in the exhaust gas purification apparatus and method using the three-way catalyst and the HC adsorption purification type catalyst as described above, adsorption and purification of HC are performed as follows. That is, when the temperature of the exhaust system is low immediately after the engine is started, the HC in the exhaust gas discharged from the internal combustion engine is HC
It is adsorbed by the adsorption purification type catalyst. When the temperature rises, H in the exhaust gas discharged from the internal combustion engine
C becomes purified by the activated three-way catalyst, and in the HC adsorption purification type catalyst, the HC adsorbed when the temperature is low is desorbed from the HC adsorption purification type catalyst and purified. Like

However, the HC purification capacity of this HC adsorption purification type catalyst is limited, and when a large amount of HC adsorbed is rapidly desorbed or the amount of exhaust gas is large when the temperature suddenly rises. When a sufficient purification reaction time cannot be secured, etc., a large amount of HC that cannot be purified can be discharged downstream (beyond the allowable amount) and released into the atmosphere. In particular, in the exhaust gas purifying apparatus and method using the three-way catalyst and the HC adsorption purification type catalyst as described above, when considering the HC adsorption / desorption characteristics or the HC purification characteristics depending on the temperature of each catalyst, the three-way catalyst is It is preferable that the three-way catalyst is arranged upstream and the HC adsorption / purification catalyst is arranged downstream of the three-way catalyst so that the temperature is easily raised and the HC adsorption / purification catalyst is hard to be raised. Then, it is also impossible to remove the HC that has been desorbed from the HC adsorption purification type catalyst and could not be purified there by the three-way catalyst.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to remove HC desorbed from HC adsorption purification means (HC adsorption purification type catalyst) by the HC adsorption purification means. It is an object of the present invention to provide an exhaust gas purification device and method capable of performing purification at a target predetermined purification rate.

[0005]

As a means for solving the above problems, the present invention provides an exhaust gas purifying apparatus and an exhaust gas purifying method described in each of the claims.

A first aspect of the present invention has a function of adsorbing HC in the exhaust gas flowing when the temperature of the HC adsorbing and purifying means is low, and desorbing the adsorbed HC and purifying it when the temperature rises. In an exhaust gas purification device in which the adsorption purification means is arranged in an exhaust gas passage through which exhaust gas discharged from an internal combustion engine passes, a bypass passage bypassing the HC adsorption purification means, and an exhaust gas flowing through the HC adsorption purification means And a flow rate control means for controlling the flow rate of the exhaust gas flowing through the HC adsorbing and purifying means by adjusting the ratio between the flow rate of the exhaust gas flowing through the bypass passage and the flow rate of the exhaust gas flowing through the bypass passage. The flow rate of the exhaust gas can purify HC desorbed from the HC adsorption purification means at a predetermined purification rate by the HC adsorption purification means. As it will become less than a predetermined upper limit flow rate is controlled by the flow rate control means, to provide an exhaust gas purifying device.

H desorbed from the HC adsorption purification means
C is usually purified by the HC adsorbing / purifying means, but cannot be completely purified when HC is rapidly desorbed in a large amount or when the amount of exhaust gas is large and sufficient purification reaction time cannot be secured. There is a risk that a large amount will be discharged downstream and released to the atmosphere. According to the present invention, by controlling the flow rate of the exhaust gas flowing through the HC adsorbing and purifying means to be equal to or less than the predetermined upper limit flow rate, a sufficient purifying reaction time can be secured, and the like. Since the desorbed HC can be purified by the HC adsorption purification means at a predetermined purification rate, the release of unpurified HC to the atmosphere is suppressed.

In the second invention, in the first invention,
The upper limit flow rate is set low according to the deterioration of the HC adsorption performance or purification performance of the HC adsorption purification means. As a result, even when the HC adsorption performance or purification performance of the HC adsorption purification means is deteriorated, the above-mentioned control of the flow rate of the exhaust gas flowing through the HC adsorption purification means can be performed correspondingly, so that the HC adsorption purification means HC It is possible to prevent the amount of unpurified HC released to the atmosphere from increasing due to the deterioration of the adsorption performance or the purification performance.

According to a third aspect of the invention, in the first or second aspect of the invention, the control of the flow rate of the exhaust gas flowing through the HC adsorption purification means by the flow rate control means is performed by the HC control method.
It is not performed when the temperature of the adsorption purification means is lower than the predetermined temperature, and is performed when the temperature of the HC adsorption purification means becomes equal to or higher than the predetermined temperature. As a result, when the temperature of the HC adsorption purification means reaches the temperature at which HC starts to be desorbed, H
The above-mentioned control of the flow rate of the exhaust gas flowing through the C adsorption purification means can be performed, and the flow rate control execution timing can be optimized.

In the fourth invention, in the third invention,
The predetermined temperature is set low according to the deterioration of the HC adsorption performance or purification performance of the HC adsorption purification means.
Also according to this invention, it is possible to obtain substantially the same operation and effect as the second invention. According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, an HC purifying means having a function of purifying HC in an active state is further provided upstream of the HC adsorbing and purifying means, and the flow rate controlling means is provided. The control of the flow rate of the exhaust gas flowing through the HC adsorbing / purifying means by means of is performed only when the HC purifying means is in the active state.

According to the present invention, when a part of the exhaust gas bypasses the downstream HC adsorption purification means during the flow rate control by the flow rate control means, the H in the exhaust gas is increased.
Since C has been purified first by the upstream HC purification unit, it is possible to reliably suppress the release of unpurified HC to the atmosphere. In a sixth aspect based on any one of the first to fifth aspects, in the control of the flow rate of exhaust gas flowing through the HC adsorption purification means by the flow rate control means,
The flow rate of the exhaust gas flowing through the HC adsorption purification means is gradually changed. As a result, the pressure loss change (back pressure change) of the exhaust system can be made gentle, and the torque fluctuation of the internal combustion engine can be reduced.

In the seventh invention, in the first invention,
The flow rate control means is a valve provided in the bypass passage, and the valve is a valve that automatically opens and closes according to the pressure of the exhaust gas acting on the valve body. According to this invention,
The control for the flow rate control means can be omitted, and the operation and effect substantially similar to those of the first aspect of the invention can be obtained with a simple configuration. In the eighth invention, in any one of the first to seventh inventions, a part of the bypass passage constitutes a resonance chamber or an expansion chamber and has a sound deadening function. As a result, the muffler (silencer) and the exhaust gas purifying device can be integrally configured, and the mountability can be improved.

A ninth aspect of the invention is to adsorb HC in the exhaust gas flowing when the temperature of the HC adsorbing and purifying means is low, and to desorb the adsorbed HC and purify it when the temperature rises. In an exhaust gas purification method in which the adsorption purification means is arranged in an exhaust gas passage through which exhaust gas discharged from an internal combustion engine passes, the temperature of the HC adsorption purification means is equal to or higher than a temperature at which HC starts to desorb from the HC adsorption purification means. At times, there is provided an exhaust gas purification method characterized in that only part of the exhaust gas discharged from the internal combustion engine is made to flow through the HC adsorption purification means. Also according to the present invention, the HC that is desorbed from the HC adsorbing and purifying means by ensuring the purifying reaction time can be sufficiently purified by the HC adsorbing and purifying means. Is suppressed.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or similar components are designated by common reference numerals.

FIG. 1 shows a case where the present invention is applied to a gasoline engine. The present invention can also be applied to a cylinder injection type spark ignition type internal combustion engine and other types of internal combustion engines such as a diesel engine. In FIG. 1, 2 is an engine body, 4 is an intake passage, and 6 is an exhaust gas passage. An exhaust gas purifying device 10 is provided in the exhaust gas passage 6. Regarding the exhaust gas purifying device 10 installed in this portion, the exhaust gas purifying devices 20, 20 ', 30, 40, 50 having five different configurations will be described later. A detailed explanation will be given by listing.

The electronic control unit (ECU) 8 is a CPU
(Central processing unit), RAM (Random access memory), ROM (Read only memory), and a digital computer of a known type in which input / output ports are connected by a bidirectional bus. In addition to performing basic control of the engine such as amount control, in each embodiment of the present invention as described below, signals are also exchanged with each component of the exhaust gas purification device, and control of the exhaust gas purification device is also performed. .

FIG. 2 is a schematic diagram showing the structure of an exhaust gas purification device 20 installed in the portion of the exhaust gas purification device 10 shown in FIG. 1 and constituting a part of the exhaust gas passage 6. In the figure, the exhaust gas flows from the left side to the right side of the figure as indicated by the arrow. As shown in FIG. 2, the exhaust gas purification device 20 has a main passage 16 provided with a three-way catalyst 12 on the upstream side and an HC adsorption purification type catalyst (hereinafter, referred to as “adsorption purification catalyst”) 14 on the downstream side, A bypass passage 18 is provided in a portion between the three-way catalyst 12 and the adsorption / purification catalyst 14 to branch from the main passage 16 and join the main passage 16 on the downstream side of the adsorption / purification catalyst 14. Adsorption purification catalyst 14
Is a carrier in which a precious metal such as platinum is supported on an HC adsorbent such as zeolite or silica.
Has a function of desorbing the adsorbed HC when the temperature rises and purifying the desorbed HC by an oxidation reaction. On the other hand, the three-way catalyst 12 has a function of purifying HC in the exhaust gas when the temperature becomes higher than the activation temperature and becomes active. In addition, the exhaust gas purifying apparatus 20 ′, 30, 40 described in the present specification, including the exhaust gas purifying apparatus 20,
Although the three-way catalyst 12 is used in the configuration of 50, another type of catalyst (for example, a NOx catalyst or an oxidation catalyst) may be used instead of the three-way catalyst 12 as long as it has a function of purifying HC. Good.

In the bypass passage 18, the adsorption purification catalyst 14
Adjusting valve as a flow rate control means for controlling the flow rate of the exhaust gas flowing through the adsorption purification catalyst 14 by adjusting the ratio of the flow rate of the exhaust gas flowing through the bypass passage 18 and the flow rate of the exhaust gas bypassing the adsorption purification catalyst 14. 22 is provided. The adjusting valve 22 is a drive unit 24 connected to the ECU 8.
If necessary, the drive unit 24 allows a substantially closed state in which almost all the exhaust gas passes through the adsorption purification catalyst 14 and a large part of the exhaust gas (for example, 90% of the total exhaust gas).
(Percentage) is adjusted between the fully open state through the bypass passage 18. That is, the control valve 22 is controlled by a signal from the ECU 8, and the flow rate of the exhaust gas flowing through the adsorption purification catalyst 14 is controlled.

Incidentally, at the time of starting the engine, normally,
The adjusting valve 22 is fully closed. This is because when the engine is started, the temperatures of the two catalysts 12 and 14 are both low, so that the HC in the exhaust gas needs to be adsorbed by the adsorption purification catalyst 14, and for that purpose, the total exhaust gas discharged from the engine is exhausted. This is because it is necessary to pass through the adsorption purification catalyst 14. Not only the exhaust gas purifying device 20 but also the three-way catalyst 12 on the upstream side of the exhaust passage and the adsorption purification catalyst 1 on the downstream side of the exhaust passage.
In the exhaust gas purifying apparatus in which No. 4 is arranged, HC in the exhaust gas is generally removed as described below, and the release of HC to the atmosphere is suppressed.

That is, when the temperature of both the three-way catalyst 12 and the adsorption purification catalyst 14 is low, such as immediately after the engine is started, most of the HC contained in the exhaust gas and flowing from the upstream is in the active state. After passing through the three-way catalyst 12 which is not set, it is adsorbed by the adsorption purification catalyst 14. Then, when the temperature of both catalysts 12 and 14 rises due to continued operation, this time, the three-way catalyst 12 becomes active and most of the HC flowing from the upstream side is purified. Become. At this time, in the adsorption purification catalyst 14, HC adsorbed when the temperature is low is desorbed and purified by an oxidation reaction.

The HC in the exhaust gas is normally removed in this way and its release to the atmosphere is suppressed. However, when the HC adsorbed in the adsorption purification catalyst 14 is rapidly desorbed, When the flow rate of exhaust gas flowing through the adsorption purification catalyst 14 is large and sufficient reaction time for purifying HC in the adsorption purification catalyst 14 cannot be secured, etc., it is possible to purify HC at a target predetermined purification rate. I can't
There is a risk that a large amount of unpurified HC will flow downstream (for example, exceeding the allowable amount) and be released into the atmosphere.

The present invention has been made in view of the above problems. Next, a method for removing HC in exhaust gas which solves the above problems and which can be carried out by the present exhaust gas purifying apparatus 20. Will be described. In this method, by controlling the adjusting valve 22 so that the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 becomes equal to or less than a predetermined flow rate Qm, the HC desorbed from the adsorption purification catalyst 14 is purified. The adsorbing and purifying catalyst 14 can purify the desorbed HC at a predetermined purifying rate by ensuring a sufficient reaction time.

When the flow rate of the exhaust gas flowing through the adsorption purification catalyst 14 increases, desorption of the adsorbed HC is promoted, and the desorbed HC stays in the adsorption purification catalyst 14 for a shorter period of time for purification. It becomes impossible to secure a sufficient reaction time. Therefore, the adsorption purification catalyst 14
When the flow rate of the exhaust gas flowing through the exhaust gas increases, a large amount of HC that cannot be purified flows downstream and may be released to the atmosphere. The predetermined flow rate Qm is the maximum flow rate at which such inconvenience does not occur, and the desorbed HC can be purified, that is, the desorbed HC.
When the method for removing HC described below is the upper limit flow rate that can be purified at a predetermined purification rate targeting, the flow rate Qm is obtained in advance by experiments, It is necessary to store it in the ECU 8 in advance.

FIG. 3 is a flowchart showing an example of a control routine for carrying out this method. This routine is executed by the ECU 8 by interruption at regular intervals. As described above, when the engine is started, the adjustment valve 22
Is in the fully closed state, and therefore, when the control routine is first executed after the engine is started, the regulating valve 22 is in the fully closed state. When this control routine starts, first, at step 100, the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 is estimated. There are various methods for estimating the exhaust gas flow rate Qc, which can be estimated as follows, for example.

That is, the total flow rate of exhaust gas discharged from the engine increases as the engine load Q / N (intake air amount Q / engine speed N) increases, and increases as the engine speed N increases. Become. Therefore, if the total exhaust gas flow rate is experimentally obtained in advance as a function of the engine load Q / N and the engine speed N, and this is stored in the ECU 8, each engine operation determined by the engine load Q / N and the engine speed N. The total exhaust gas flow rate in the state can be obtained. Then, in the case of the total exhaust gas flow rate in each engine operating state, the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 when the adjustment valve 22 is in each opening state can be obtained by experiment or calculation.

Therefore, the total exhaust gas flow rate as a function of the engine load Q / N and the engine speed N, and the exhaust gas flow rate Qc as a function of the total exhaust gas flow rate and the opening state of the adjusting valve 22 are obtained. So these relationships
8, the exhaust gas flow rate Qc can be obtained from each engine operating state and each opening state of the adjusting valve 22. When the adjustment valve 22 is in the fully closed state just after the engine is started, the total exhaust gas flow rate is the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14.

Alternatively, a pressure sensor (not shown) for measuring the pressure P in the portion immediately upstream of the adsorption purification catalyst 14 is provided, or a differential pressure for measuring the pressure difference ΔP between the upstream side and the downstream side of the adsorption purification catalyst 14. A flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 by providing a sensor (not shown)
The exhaust gas flow rate Qc may be estimated based on the pressure P or the pressure difference ΔP having a correlation with the above. In this case, the relationship between the exhaust gas flow rate Qc and the pressure P or the pressure difference ΔP is obtained in advance by experiments or the like, and the ECU
It is necessary to store in 8.

When the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 is estimated in step 100 by any of the methods described above, in the subsequent step 102, the exhaust gas flow rate Qc is the above-mentioned predetermined flow rate. Compared with Qm. Exhaust gas flow rate Qc in step 102
When it is determined that is equal to or less than the above-described predetermined flow rate Qm, this control routine ends, and the control of the adjusting valve 22 is not performed. On the other hand, when it is determined that the exhaust gas flow rate Qc is higher than the above-mentioned predetermined flow rate Qm, step 10
4, the control of the adjusting valve 22 is performed.

When the process proceeds to step 104, that is, the desorption of the HC adsorbed due to the large flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 is promoted, and the adsorption purification of the desorbed HC is promoted. This is the case where the residence time in the catalyst 14 becomes short and the time for the purification reaction cannot be secured sufficiently, and there is a possibility that a large amount of HC that cannot be purified will flow downstream and be released to the atmosphere. The control of the adjusting valve 22 is to increase the opening degree of the adjusting valve 22, increase the exhaust gas flow rate Qb flowing through the bypass passage 18 and reduce the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14. .

Therefore, for example, control is performed such that the regulating valve 22 which has been in the fully closed state is brought into the fully opened state. Alternatively, the adjustment valve 22 may be controlled by a signal from the ECU 8 so that the exhaust gas flow rate Qc becomes equal to or less than the predetermined flow rate Qm or becomes the predetermined flow rate Qm.
In this case, the exhaust gas flow rate Qc is a desired flow rate (for example, a predetermined flow rate Qm) from the relationship between the engine operating state used for estimating the exhaust gas flow rate Qc described above, the opening state of the adjusting valve 22, and the exhaust gas flow rate Qc. Therefore, the exhaust gas flow rate Qc can be set to a desired flow rate by controlling the drive unit 24 by a signal from the ECU 8 to bring the regulating valve 22 into the open state. . Then, such control of the adjusting valve 22 is performed until the engine is stopped, and when the engine is stopped, this control routine ends.

The control of the adjusting valve 22 is performed so that the exhaust gas flow rate Qc is gradually changed (for example, by gradually adjusting the opening state of the adjusting valve 22 to the open side). Exhaust system pressure loss change (back pressure change)
The torque fluctuation of the engine can be reduced. This also applies to other exhaust gas purification devices described later.

4 and 5, in the exhaust gas purifying apparatus 20, when the engine load is increased and the total exhaust gas flow rate is increased, the method shown in the control routine of FIG. 3 as described above is executed. In this case, the total exhaust gas flow rate, the opening of the adjustment valve 22, the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14, the exhaust gas flow rate Qb of the bypass passage 18, and the H in the exhaust gas.
It shows the change over time in the amount of C. FIG. 4 shows a case where the opening state of the adjusting valve 22 is adjusted to the open side at a stroke when the exhaust gas flow rate Qc becomes larger than a predetermined flow rate Qm.
FIG. 5 shows a case where the opening degree of the adjusting valve 22 is gradually adjusted to the open side. In these figures, line A shows the total amount of HC discharged from the engine and line B shows the amount of HC.
Indicates the amount of HC downstream of the adsorption purification catalyst 14. Further, the line B ′ indicated by the alternate long and short dash line is H at the downstream side of the adsorption purification catalyst 14 when the regulating valve 22 is not controlled, that is, when the regulating valve 22 is maintained in the fully closed state.
The amount of C is shown.

As shown in these figures, when the method shown in the control routine of FIG. 3 as described above is executed, it is adjusted that the exhaust gas flow rate Qc becomes larger than the predetermined flow rate Qm. The degree of opening of the valve 22 is adjusted, part of the exhaust gas is made to flow through the bypass passage 18, and the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14 is maintained at a predetermined flow rate Qm or less. As a result, even when the engine load increases and the total exhaust gas flow rate increases, the HC desorbed from the adsorption purification catalyst 14 can be purified by the adsorption purification catalyst 14 at a predetermined purification rate. Is maintained.

Here, in a state where the engine load increases and the exhaust gas flow rate Qc becomes larger than a predetermined flow rate Qm, that is, in a high load state, the temperature of the exhaust gas is usually high and the upstream side The three-way catalyst 12 is heated by the heat of the exhaust gas to be in an active state, and the HC contained in the exhaust gas and flowing is purified by the three-way catalyst 12. For this reason, the exhaust gas is usually the adsorption purification catalyst 1
The problem that HC is discharged to the downstream side does not occur because it flows by bypassing 4.

Further, in such a high exhaust gas temperature state, the exhaust gas flow rate Q flowing through the adsorption purification catalyst 14 is increased.
Reducing c, that is, maintaining the flow rate at or below a predetermined flow rate Qm, has the effect of suppressing the temperature rise of the adsorption purification catalyst 14 and the desorption of HC from the adsorption purification catalyst 14. Therefore, in this case, by maintaining the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14 at a predetermined flow rate Qm or less, the purification reaction time of HC is secured and the adsorption purification catalyst 14 Even if the amount of desorbed HC is reduced by suppressing the temperature rise, the desorbed HC can be completely purified in the adsorption purification catalyst 14.

From the above, by executing the method shown in the control routine of FIG. 3 as described above,
The amount of HC downstream of the adsorption purification catalyst 14 can be maintained at zero or a considerably low level. As is apparent from the above description, the increase in the amount of HC shown by the line B ′ in FIGS. 4 and 5 is due to the increase in the total amount of HC discharged from the engine shown by the line A. Rather, it is due to an increase in the amount of HC desorbed from the adsorption purification catalyst 14.

Next, with reference to FIG. 6, an exhaust gas purifying apparatus 20 'having another structure capable of carrying out a method substantially similar to the above-mentioned method and obtaining the same action and effect will be described. The basic configuration of the exhaust gas purification device 20 ′ is similar to that of the exhaust gas purification device 20 described above, but in the present exhaust gas purification device 20 ′, the degree of opening is adjusted by a signal from the ECU 8. Instead of the valve 22, another type of regulating valve 26 is provided.

The adjusting valve 26 is a type of valve that automatically opens and closes according to the pressure (more specifically, the pressure difference) of the exhaust gas acting on the valve body 28. An example of such a type of valve is a valve in which the valve body 28 is kept closed by a spring that generates a predetermined urging force. Then, in the adjusting valve 26 of this type, the above-mentioned predetermined urging force acts on the valve body 28 when the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 reaches the above-mentioned predetermined flow rate Qm. If the gas force (the difference between the force acting on the valve opening direction and the force acting on the valve closing direction) is matched, the total exhaust gas flow rate increases and the exhaust gas flow rate Qc is increased in advance. When the flow rate Qm reaches the predetermined flow rate Qm, the regulating valve 26 is automatically opened, a part of the exhaust gas is made to flow through the bypass passage 18, and the exhaust gas flow rate Qc is maintained below the predetermined flow rate Qm.

As is clear from the above description, the exhaust gas purifying device 2 is also configured in the exhaust gas purifying device 20 '.
It is possible to carry out a method similar to the above-mentioned method carried out by using 0, and obtain the same action and effect. In this case, the exchange of signals with the ECU 8 can be omitted, and the configuration of the device can be simplified. Next, with reference to FIG. 7, an exhaust gas purification device 30 having another configuration will be described. The basic configuration of the exhaust gas purification device 30 is similar to that of the exhaust gas purification device 20 described above, but in the exhaust gas purification device 30, the adsorption purification catalyst 14 is provided with a temperature sensor 32 for measuring the temperature thereof. Has been. The temperature sensor 32 is connected to the ECU 8, and the measurement result is EC
Given to U8.

Although the temperature sensor 32 is provided directly on the adsorption purification catalyst 14 in the exhaust gas purification device 30, the temperature sensor is installed downstream of the adsorption purification catalyst 14 to measure the temperature of the exhaust gas. Therefore, the adsorption purification catalyst 14
The temperature of the adsorption purification catalyst 14 may be obtained by other means such as estimating the temperature of the above. Next, a method for removing HC in the exhaust gas that can be carried out by the exhaust gas purification device 30 will be described.

As described above, in the adsorption purification catalyst 14, HC is adsorbed when the temperature is low, and when the temperature is high, the adsorbed HC is desorbed and purified by an oxidation reaction. In the method described here, the temperature Tc of the adsorption purification catalyst 14 is monitored, and when the temperature Tc reaches a temperature at which HC is desorbed (desorption start temperature) or a predetermined temperature Tm in the vicinity thereof, adsorption is performed. Purification catalyst 14
The exhaust gas flow rate Qc flowing through the exhaust gas is controlled to secure a reaction time sufficient for purifying the HC desorbed from the adsorption purification catalyst 14, and the desorbed HC is predetermined by the adsorption purification catalyst 14. It is to be able to purify at the purification rate of.

FIG. 8 is a flowchart showing an example of a control routine for carrying out this method. This routine is executed by the ECU 8 by interruption at regular intervals. In the exhaust gas purifying apparatus 30 as well, the adjusting valve 22 is in the fully closed state when the engine is started, and therefore, when the control routine is first executed after the engine is started, the adjusting valve 22 is in the fully closed state.

When this control routine starts, first in step 200, the temperature Tc of the adsorption purification catalyst 14 is estimated. In the exhaust gas purification device 30, since the temperature sensor 32 is provided on the adsorption purification catalyst 14, the temperature Tc estimated here is a measurement value of the temperature sensor 32. However, the present invention is not limited to this, and the temperature Tc of the adsorption purification catalyst 14 can be estimated by various methods as described above. For example, a temperature sensor is provided downstream or upstream of the adsorption purification catalyst 14,
Alternatively, the temperature Tc may be estimated on the basis of the temperature of the exhaust gas flowing therethrough, which is provided both upstream and downstream. In this case, the relationship between the exhaust gas temperature measured by each temperature sensor and the temperature Tc is obtained in advance by an experiment or the like and stored in the ECU 8.

Alternatively, the engine cooling water temperature may be measured and the temperature Tc may be estimated based on the measured temperature. In this case, the relationship between the engine cooling water temperature and the temperature Tc needs to be obtained in advance by experiments or the like and stored in the ECU 8. Alternatively, the temperature Tc may be estimated based on the engine operating state. That is, the temperature of exhaust gas discharged from the engine and the total amount of exhaust gas are determined by the engine load Q / N.
And the engine operating state determined by the engine speed N, the temperature Tc of the adsorption purification catalyst 14 also correlates with this engine operating state. Therefore, the temperature Tc is set to the engine load Q / N.
And, as a function of the engine speed N, the temperature Tc in each engine operating state, which is determined by the engine load Q / N and the engine speed N, can be calculated by experimentally preliminarily determining and storing this in the ECU 8. As still another method, the temperature Tc may be estimated based on the elapsed time from the engine start. In this case, the relationship between the elapsed time from the start of the engine and the temperature Tc is previously obtained by an experiment and stored in the ECU 8.

When the temperature Tc of the adsorption purification catalyst 14 is estimated in step 200 by any of the methods described above, the temperature Tc is compared with a predetermined temperature Tm in the following step 202. The temperature Tm is a temperature at which HC starts to desorb from the adsorption purification catalyst 14 (desorption start temperature) or a temperature in the vicinity thereof, and is preferably a temperature slightly lower than the desorption start temperature.

When it is determined in step 202 that the temperature Tc is lower than the predetermined temperature Tm, this control routine ends and the regulating valve 22 is not controlled. That is, in this case, since the temperature of the adsorption purification catalyst 14 is low, desorption of the adsorbed HC does not occur, and thus the desorbed H
In order to allow C to be purified by the adsorption purification catalyst 14 at a predetermined purification rate, it is necessary to control the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14 in order to secure a sufficient reaction time for purifying HC. Therefore, the regulating valve 22 is not controlled.

On the other hand, the temperature Tc is the above-mentioned predetermined temperature T
When it is determined that the value is equal to or greater than m, the process proceeds to step 204, and the adjustment valve 22 is controlled. The control of the regulating valve 22 in step 204 is similar to the control of the regulating valve 22 in step 104 of the method described above with reference to the flowchart of FIG. 3 in relation to the exhaust gas purification device 20, and for example, fully closed. Control such that the adjustment valve 22 that has been in the state is fully opened is performed. Or the exhaust gas flow rate Qc
So that the flow rate is equal to or less than the predetermined flow rate Qm described above,
Alternatively, the adjustment valve 22 may be controlled by a signal from the ECU 8 so that the flow rate Qm is set in advance. And
Such control of the regulating valve 22 is performed until the engine is stopped,
This control routine ends when the engine is stopped.

FIG. 9 shows the exhaust gas purifying device 30
When the engine load increases and the total exhaust gas flow rate increases, the total exhaust gas flow rate, the opening degree of the adjusting valve 22, and the temperature Tc of the adsorption purification catalyst 14 when the method shown in the control routine of FIG. 8 is performed. 3 shows changes over time in the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 and the amount of HC in the exhaust gas. This figure shows a case where the opening state of the adjusting valve 22 is adjusted to the open side at once when the temperature Tc of the adsorption purification catalyst 14 reaches a predetermined temperature Tm.

In the figure, the expression of the portion showing the amount of HC is the same as in the case of FIGS. 4 and 5, line A shows the total amount of HC discharged from the engine, and line B shows the downstream of the adsorption purification catalyst 14. Shows the amount of HC in the. In addition, the line B indicated by the one-dot chain line
′ Is the adsorption purification catalyst 1 when the control of the adjusting valve 22 is not performed, that is, when the adjusting valve 22 is maintained in the fully closed state.
4 shows the amount of HC downstream of No. 4. Note that, as in the case of FIGS. 4 and 5, the increase in the amount of HC shown by the line B ′ is not due to the increase in the total amount of HC discharged from the engine shown by the line A. This is due to an increase in the amount of HC desorbed from the purification catalyst 14. In addition, what is indicated by a chain line in the portion showing the temperature Tc of the adsorption purification catalyst 14 is the temperature Tc when the adjustment valve 22 is not controlled, that is, when the adjustment valve 22 is maintained in the fully closed state. Is.

As shown in this figure, when the method shown in the control routine of FIG. 8 is carried out, the temperature T
When c reaches a predetermined temperature Tm, the opening degree state of the adjusting valve 22 is adjusted, a part of the exhaust gas is made to flow through the bypass passage 18, and the exhaust gas flow rate Qc becomes equal to or less than the above-mentioned predetermined flow rate Qm. Maintained. As a result, even when the engine load increases and the total exhaust gas flow rate increases, the HC desorbed from the adsorption purification catalyst 14 can be purified by the adsorption purification catalyst 14 at a predetermined purification rate. Is maintained.

When the temperature Tc of the HC adsorption purification catalyst 14 rises to reach the predetermined temperature Tm, the temperature of the exhaust gas is usually high and the three-way catalyst 12 on the upstream side is exhausted. The temperature of the exhaust gas is raised by the heat of the gas to be in the active state, and the HC contained in the exhaust gas and flowing therein is purified by the three-way catalyst 12. Therefore, the exhaust gas normally flows by-passing the adsorption purification catalyst 14, so that there is no problem that HC is discharged to the downstream side.

Further, the temperature Tc of the adsorption purification catalyst 14 shown in FIG.
As shown in the portion indicated by, when the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14 is reduced by performing this method, the temperature rise of the adsorption purification catalyst 14 is suppressed. As a result, H from the adsorption purification catalyst 14
Desorption of C is suppressed, and this also enables complete purification of the desorbed HC in the adsorption purification catalyst 14.

From the above, the HC amount downstream of the adsorption purification catalyst 14 can be maintained at zero or a considerably low level by implementing the method shown in the control routine of FIG. Further, according to this method, the flow rate Q of the exhaust gas flowing through the adsorption purification catalyst 14 corresponding to the temperature at which the adsorption purification catalyst 14 begins to desorb HC
Since the above control of c can be performed, the flow rate control execution timing can be optimized.

Next, an exhaust gas purifying device 40 having still another structure will be described with reference to FIG. The basic configuration of this exhaust gas purification device 40 is the above-mentioned exhaust gas purification device 2
The same as 0, but in the exhaust gas purification device 40, the three-way catalyst 1 provided on the upstream side of the adsorption purification catalyst 14
2 is provided with a temperature sensor 34 for measuring the temperature. This temperature sensor 34 is connected to the ECU 8,
The measurement result is given to the ECU 8.

Although the temperature sensor 34 is provided directly on the three-way catalyst 12 in the exhaust gas purifying apparatus 40, the temperature sensor is installed downstream of the three-way catalyst 12 to measure the temperature of the exhaust gas. Therefore, the temperature of the three-way catalyst 12 may be obtained by other means such as estimating the temperature of the three-way catalyst 12. Next, a method for removing HC in the exhaust gas that can be carried out by the exhaust gas purification device 40 will be described.

As described above, the exhaust gas purification device in which the three-way catalyst 12 is arranged upstream of the exhaust gas passage and the adsorption purification catalyst 14 is arranged downstream thereof as described in the present specification. In the case where the temperature of both the three-way catalyst 12 and the adsorption purification catalyst 14 is low, such as immediately after the engine is started, the HC contained in the exhaust gas and flowing from the upstream
Almost pass through the three-way catalyst 12 that is not in the active state, and are adsorbed by the adsorption purification catalyst 14. Then, when the temperature of both catalysts 12 and 14 rises due to the operation of the engine being continued, this time, the three-way catalyst 12 becomes active and most of the HC flowing from the upstream is purified. At the same time, in the adsorption purification catalyst 14, the HC adsorbed when the temperature is low is desorbed and purified by an oxidation reaction. The method described below determines the active state of the three-way catalyst 12 arranged on the upstream side, and
Only when 2 is in the active state, the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14 is controlled so that a part of the exhaust gas bypasses the adsorption purification catalyst 14 arranged on the downstream side. Is surely prevented from bypassing the adsorption purification catalyst 14 and discharged to the downstream, and at the same time, the reaction time is secured so that HC desorbed from the adsorption purification catalyst 14 can be purified. The adsorbed purification catalyst 14 purifies the obtained HC at a predetermined purification rate.

FIG. 11 is a flow chart showing an example of a control routine for carrying out this method. This routine is executed by the ECU 8 by interruption at regular intervals. In the exhaust gas purifying apparatus 40 as well, the adjusting valve 22 is in the fully closed state when the engine is started, and therefore, when the control routine is first executed after the engine is started, the adjusting valve 22 is in the fully closed state.

When this control routine starts, first, at step 302, it is judged if the three-way catalyst 12 is in the active state. Since the temperature sensor 34 is provided in the three-way catalyst 12 in the exhaust gas purification device 40 as described above, whether the temperature Ts measured here is equal to or higher than the activation temperature Ta of the three-way catalyst 12 or not. Is determined. In this case, as a matter of course, if the temperature Ts is equal to or higher than the activation temperature Ta, the three-way catalyst 12 is in the activated state. As for the temperature Ts of the three-way catalyst 12, as described above, a temperature sensor is installed downstream of the three-way catalyst 12, and the temperature of the exhaust gas is measured to estimate the temperature of the three-way catalyst 12.
It may be obtained by other means. That is, the temperature Ts of the three-way catalyst 12 is set to the adsorption purification catalyst 14 described in relation to the method shown in the control routine of FIG.
The temperature Tc can be estimated by using a method substantially similar to each of the temperature Tc estimation methods, and thus the temperature Ts of the three-way catalyst 12 thus obtained and the activation temperature Ta may be compared. .

Alternatively, the activation state of the three-way catalyst 12 may be determined by a method that does not use the temperature Ts. That is, for example, an exhaust gas sensor capable of measuring the HC concentration, NOx concentration, CO concentration, etc. in the exhaust gas is provided between the three-way catalyst 12 and the adsorption purification catalyst 14, and the three-way catalyst 12 is measured by the measured value of the exhaust gas sensor. You may make it determine whether it is in an active state. Alternatively, the time from the engine start-up when the three-way catalyst 12 is activated may be obtained in advance, and the three-way catalyst 12 may be activated when the time has elapsed from the engine start-up.

At step 302, the active state of the three-way catalyst 12 is determined by any of the methods described above,
When it is determined that the three-way catalyst 12 is not in the active state, this control routine ends and the control of the adjusting valve 22 is not performed. That is, in this case, since the three-way catalyst 12 is not in the active state, the exhaust gas that has passed through the three-way catalyst 12 is still H
C is included. Therefore, when the adjustment valve 22 is controlled to control the exhaust gas flow rate Qc flowing through the adsorption purification catalyst 14 so that a part of the exhaust gas bypasses the adsorption purification catalyst 14, the HC in the bypassed exhaust gas is May be released into the atmosphere unpurified. Therefore, the regulating valve 22 is not controlled and the fully closed state is maintained.

On the other hand, when it is determined that the three-way catalyst is in the active state, the routine proceeds to step 304, where the adjusting valve 22 is controlled. The control of the regulating valve 22 in step 304 is similar to the control of the regulating valve 22 in step 104 of the method described above with reference to the flowchart of FIG. Description is omitted. The regulation valve 22 is controlled until the engine is stopped, and when the engine is stopped, this control routine ends.

As described above, when the method shown in the control routine of FIG. 11 is executed, the adjusting valve 22 is fully closed until the three-way catalyst 12 arranged on the upstream side becomes active. Since it is maintained, it is possible to reliably prevent the HC contained in the exhaust gas from being discharged downstream by the exhaust gas containing the HC bypassing the HC adsorption purification catalyst 14. Then, when the three-way catalyst 12 becomes active,
The opening state of the adjusting valve 22 is adjusted, and a part of the exhaust gas is made to flow through the bypass passage 18.
Is maintained below the above-mentioned predetermined flow rate Qm, so even when the engine load rises and the total exhaust gas flow rate increases, the HC desorbed from the adsorption purification catalyst 14 is adsorbed in the adsorption purification catalyst 14. The state that can be purified at a predetermined purification rate is maintained.

In this way, the amount of HC in the downstream of the adsorption purification catalyst 14 can be maintained at zero or a considerably low level by implementing the method shown in the control routine of FIG.

The HC adsorption performance of the adsorption purification catalyst 14 (that is, the amount of HC that can be adsorbed per unit time) or the purification performance (that is, H that can be purified per unit time).
The control method of the adjusting valve 22 in the method shown in each control routine may be changed in consideration of the deterioration of the C amount). That is, the adsorption purification catalyst 14 gradually deteriorates in its HC adsorption performance or purification performance (hereinafter referred to as “HC purification performance etc.”) as it is continuously used. Therefore, the amount of HC that can be purified at the start of use may not be purified after deterioration. In such a case, for example, in the method shown in the control routine of FIG. 3, by adjusting the predetermined flow rate Qm according to the usage time of the adsorption purification catalyst 14, the regulation valve control corresponding to the deterioration of the HC purification performance and the like. Can be implemented. That is, when the use of the adsorption purification catalyst 14 is continued to some extent and the deterioration of the HC purification performance and the like progresses, the predetermined flow rate Qm is set to be lower than when the use of the adsorption purification catalyst 14 is started.
The flow rate Qc of the exhaust gas flowing through the exhaust gas is kept smaller than that at the start of use so that the HC desorbed by the adsorption purification catalyst 14 having deteriorated HC purification performance and the like can be purified at a predetermined purification rate. can do.

Further, in the method shown in the control routine of FIG. 8, the predetermined temperature Tm is similarly set in the adsorption purification catalyst 1.
The adjustment valve control corresponding to the deterioration of the HC purification performance of the adsorption purification catalyst 14 and the like can also be performed by changing it according to the usage time of No. 4. In this case, the longer the usage time is, the lower the predetermined temperature Tm is set. The adsorption purification catalyst 1
The degree of deterioration of the HC purification performance of No. 4 may be determined by other methods such as providing an HC sensor downstream of the adsorption purification catalyst 14 in addition to the above-described usage time.

Further, the above-mentioned exhaust gas purification devices 20, 3
Any two or three of the configurations of 0 and 40 are combined, and any two or three of the corresponding methods shown in the control routines of FIGS. 3, 8 and 11 are combined. All methods may be combined and implemented. The respective configurations and methods in the case of combining these are considered to be generally apparent from the above description and the drawings, so detailed description will be omitted, but for example, the exhaust gas purification device 2
0 and the structure of the exhaust gas purifying device 40 are combined (in this case, the illustrated structure is the exhaust gas purifying device 40 of FIG. 10).
When the method shown in the control routine of FIG. 3 and the method shown in the control routine of FIG. 11 are combined and executed, the three-way catalyst 12 is activated. When the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 becomes larger than the predetermined flow rate Qm, the adjusting valve 22 causes the adjusting valve 22 to perform step 104 (FIG. 3) or step 304 (FIG. 1).
It is controlled as in 1).

Further, the exhaust gas purification devices 20, 30, 40
In the case where all three configurations are combined and the above three methods are combined and carried out, the temperature Tc of the adsorption purification catalyst 14 is predetermined when the three-way catalyst 12 is in the active state. When the temperature becomes equal to or higher than the temperature Tm and the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14 becomes higher than the predetermined flow rate Qm, the adjustment valve 22 is controlled. By combining several methods in this way, unnecessary control of the regulating valve 22 can be reduced, and by including the method shown in the control routine of FIG. It is possible to reliably suppress the release of the generated HC to the atmosphere.

Further, the above-mentioned exhaust gas purifying devices 20, 2
0 ', 30, 40 can be configured integrally with a muffler (silencer). FIG. 12 shows a case where the exhaust gas purification device 20 shown in FIG. 2 is integrated with a muffler (exhaust gas purification device 50). Here, the case of the exhaust gas purification device 50 is taken as an example. explain. In the exhaust gas purification device 50, a muffling function is exhibited as described below.

That is, when the regulating valve 22 is closed, the exhaust gas passes through the three-way catalyst 12 and then all of the exhaust gas is adsorbed and purified by the adsorption purification catalyst 14 as shown by the solid arrow in the figure.
And is discharged from the exhaust gas purification device 50. At this time, the space I, which is a part of the main passage 16, acts as an expansion chamber and exhibits a sound deadening function. Further, the space II which is a part of the bypass passage 18 constitutes a resonance chamber because the adjusting valve 22 is closed, and exhibits a sound deadening function.

On the other hand, when the adjusting valve 22 is opened to adjust the flow rate Qc of the exhaust gas flowing through the adsorption purification catalyst 14, the exhaust gas passing through the three-way catalyst 12 is partially adsorbed. After passing through the purification catalyst 14, the rest of the bypass passage 18 (space I
After passing through I), each reaches the space I which is a part of the main passage 16, and is then discharged from the exhaust gas purification device 50. In this case, the space I that is a part of the main passage 16
The space II, which is a part of the bypass passage 18, acts as an expansion chamber, and exhibits a sound deadening function.

As described above, with the configuration shown in FIG. 12, the exhaust gas purifying device can be provided with a sound deadening function. Then, by integrally configuring the muffler and the exhaust gas purifying device in this way, the mountability can be improved.

[0072]

According to the first aspect of the invention, by controlling the flow rate of the exhaust gas flowing through the HC adsorption purification means,
Since the HC desorbed from the C adsorption purification means can be purified by the HC adsorption purification means at a predetermined purification rate, the release of unpurified HC to the atmosphere is suppressed.

According to the second aspect of the present invention, it is possible to prevent the amount of unpurified HC released to the atmosphere from increasing due to deterioration of the HC adsorption performance or purification performance of the HC adsorption purification means. According to the third aspect, it is possible to optimize the timing of controlling the flow rate of the exhaust gas flowing through the HC adsorption purification means. The fourth invention can also obtain substantially the same effects as the second invention.

According to the fifth aspect, it is possible to reliably suppress the release of unpurified HC into the atmosphere. According to the sixth aspect, the pressure loss change (back pressure change) of the exhaust system can be made gentle, and the torque fluctuation of the internal combustion engine can be reduced. According to the seventh invention, the control of the flow rate control means can be omitted, and the same effect as the first invention can be obtained with a simple configuration.

According to the eighth invention, a muffler (silencer)
The exhaust gas purifying device and the exhaust gas purifying device can be integrally formed, and the mountability can be improved. The ninth invention also suppresses the release of unpurified HC into the atmosphere.

[Brief description of drawings]

FIG. 1 is a diagram showing a case where an exhaust gas purifying apparatus of the present invention is applied to a gasoline engine.

FIG. 2 is an explanatory view showing an exhaust gas purification device of the present invention.

FIG. 3 is a flowchart showing a control carried out by the exhaust gas purifying apparatus shown in FIG.

FIG. 4 is a total exhaust gas flow rate, an adjustment valve opening degree, an exhaust gas flow rate flowing through an adsorption purification catalyst, an exhaust gas flow rate and an exhaust gas flow in a bypass passage when the control shown in FIG. 3 is performed. It shows the change with time of the amount of HC in the inside, and is the case when the opening state of the adjusting valve is adjusted at once.

FIG. 5 is a view similar to FIG. 4 and shows a case where the opening state of the adjusting valve is gradually adjusted.

FIG. 6 is an explanatory view showing another exhaust gas purification device of the present invention.

FIG. 7 is an explanatory view showing still another exhaust gas purification device of the present invention.

FIG. 8 is a flowchart showing control executed by the exhaust gas purification device shown in FIG. 7.

9 is a total exhaust gas flow rate when the control shown in FIG. 8 is performed, an adjustment valve opening degree, an adsorption purification catalyst temperature,
It is a graph showing changes over time in the flow rate of exhaust gas flowing through the adsorption purification catalyst and the amount of HC in the exhaust gas, in the case where the opening state of the adjusting valve is adjusted all at once.

FIG. 10 is an explanatory view showing another exhaust gas purification device of the present invention.

FIG. 11 is a flowchart showing control executed by the exhaust gas purification device shown in FIG. 10.

FIG. 12 is a diagram for explaining a case where the exhaust gas purification device shown in FIG. 2 is configured integrally with a muffler.

[Explanation of Codes] 2 ... Engine Main Body 4 ... Intake Passage 6 ... Exhaust Gas Passage 8 ... Electronic Control Unit (ECU) 10, 20, 20 ', 30, 40, 50 ... Exhaust Gas Purifier 12 ... Catalyst 14 ... HC adsorption purification catalyst 16 ... Main passage 18 ... Bypass passages 22, 26 ... Regulator valve 24 ... Drive unit 28 ... Valve bodies 32, 34 ... Temperature sensor

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/18 F01N 3/24 EN 3/24 B01D 53/36 103B 53/34 120D F term (reference) 3G091 AA02 AA17 AA18 AA28 AB02 AB03 AB10 BA03 BA14 BA15 BA19 BA31 BA32 BA33 CA12 CA13 CB02 CB08 DA01 DA02 DA05 DB10 EA01 EA03 EA05 EA16 EA17 EA18 EA19 EA30 EA31 EA32 EA33 FA02 FA04 FB10 FB11 FB12 FC04 FC07 FC08 GB01Y GB05W GB06W GB09Y GB10Y GB16Y HA08 HA19 HA36 HA37 HA38 HA39 HB03 4D002 AA40 AC10 BA04 CA07 DA45 DA46 DA70 EA08 GA03 GB01 4D048 AA06 AA13 AA18 AB01 AB05 CC32 CC46 DA01 DA02 DA05 DA06 EA04

Claims (9)

[Claims] 1. An HC adsorbing and purifying means having a function of adsorbing HC in the exhaust gas flowing when the temperature of the HC adsorbing and purifying means is low, and desorbing and adsorbing the adsorbed HC when the temperature rises. In an exhaust gas purification device arranged in an exhaust gas passage through which exhaust gas discharged from an internal combustion engine passes, a bypass passage bypassing the HC adsorption purification means, an exhaust gas flow rate flowing through the HC adsorption purification means, and A flow rate control means for adjusting the ratio of the flow rate of the exhaust gas flowing through the bypass passage to control the flow rate of the exhaust gas flowing through the HC adsorption purification means, and the flow rate of the exhaust gas flowing through the HC adsorption purification means. However, the HC that is desorbed from the HC adsorption / purification means is
An exhaust gas purification device controlled by the flow rate control means so that the flow rate becomes equal to or lower than a predetermined upper limit flow rate that can be purified at a predetermined purification rate by the C adsorption purification means. 2. The exhaust gas purifying apparatus according to claim 1, wherein the upper limit flow rate is set low according to deterioration of the HC adsorption performance or purification performance of the HC adsorption purification means. 3. The control of the flow rate of the exhaust gas flowing through the HC adsorption purification means by the flow rate control means is performed by the H
The exhaust gas purification apparatus according to claim 1 or 2, which is not performed when the temperature of the C adsorption purification means is lower than a predetermined temperature, but is not performed when the temperature of the HC adsorption purification means is equal to or higher than the predetermined temperature. 4. The exhaust gas purification device according to claim 3, wherein the predetermined temperature is set low in accordance with deterioration of the HC adsorption performance or purification performance of the HC adsorption purification means. 5. Further, upstream of the HC adsorption purification means,
When the HC purification means is in an active state, the flow rate control means controls the flow rate of the exhaust gas flowing through the HC adsorption purification means by the HC purification means having a function of purifying HC in the activated state. The exhaust gas purifying apparatus according to any one of claims 1 to 4, wherein the exhaust gas purifying apparatus according to any one of claims 1 to 4. 6. In the control of the flow rate of exhaust gas flowing through the HC adsorption purification means by the flow rate control means,
The exhaust gas purification apparatus according to any one of claims 1 to 5, wherein the flow rate of the exhaust gas flowing through the HC adsorption purification means is gradually changed. 7. The flow rate control means is a valve provided in the bypass passage, and the valve is a valve that automatically opens and closes according to the pressure of exhaust gas acting on the valve body. Exhaust gas purification device. 8. The exhaust gas purifying apparatus according to claim 1, wherein a part of the bypass passage constitutes a resonance chamber or an expansion chamber and has a sound deadening function. 9. An HC adsorbing and purifying means having a function of adsorbing HC in the exhaust gas flowing when the temperature of the HC adsorbing and purifying means is low, and desorbing and adsorbing the adsorbed HC when the temperature rises. In the exhaust gas purifying method, which is performed by disposing the exhaust gas in the exhaust gas passage through which the exhaust gas discharged from the internal combustion engine passes, the temperature of the HC adsorbing and purifying means is the HC
When the temperature is higher than the temperature at which HC starts to desorb from the adsorption purification means, only a part of the exhaust gas discharged from the internal combustion engine is used as the HC.
Characterized in that the adsorption purification means is circulated,
Exhaust gas purification method.