JPH07332074A - Exhaust emission control device - Google Patents

Abstract

PURPOSE:To provide an exhaust emission control device wherein discharge of harmful component in exhaust gas, particularly, HC is prevented in cooling of the engine, HC adsorbed by an adsorbent is separated in a short time in warming of the engine, it is returned to a catalytic device, and an adverse effect on the engine control caused by the reflux is decreased to the utmost. CONSTITUTION:Passages divided into two by a bulkhead 33 provided with a hole are formed on the back of a catalytic device 4 arranged in an exhaust pipe of an internal combustion engine 1. And an adsorbent 5 for adsorbing HC components of exhaust gas of an internal combustion engine 1 is provided on one side passage. When the exhaust gas temperature is the specific temperature or more, the exhaust gas is allowed to flow on the other side by a switch valve 8, but the adsorbent is exposed to the exhaust gas since the hole is provided on the bulkhead 33. Thereby, the HC components adsorbed by the adsorbent are easily separated by the exhaust gas temperature. The separated HC components pass circulating passage pipes 6a, 6b and returned to the upstream side of the catalytic device 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device, and more particularly to an exhaust gas purification device discharged from an internal combustion engine used in an automobile or the like.

[0002]

2. Description of the Related Art As one method for purifying exhaust gas from an automobile, there is an exhaust gas purifying method using an adsorbent carrying a precious metal (platinum, rhodium, etc.) as a catalyst. Purification of HC in exhaust gas using this adsorbent generally requires a catalyst activation temperature of 350 ° C. or higher. However,
Immediately after the engine is started, the catalyst has not reached the catalyst activation temperature, so that HC purification is practically not performed.

In order to solve the above problem, therefore, a catalyst device is provided in the exhaust system of the engine, and HC discharged during cold engine (hereinafter referred to as cold HC) is adsorbed on the upstream side or the downstream side thereof. HC containing an adsorbent for
Purification devices equipped with a trapper have been proposed (JP-A-2-135126, JP-A-4-17710, JP-A-4-31618).

The purifying device disclosed in JP-A-2-135126 is
An adsorbent device using a zeolite-based adsorbent is placed on the upstream side of the catalyst device, and the adsorbent device and the catalyst device are used together to adsorb cold HC to the adsorbent when the exhaust gas temperature is low and when the exhaust gas temperature is high. The catalyst cleans the HC desorbed from the agent and the exhaust HC from the engine. Also,
In the purification devices of JP-A-4-17710 and JP-A-4-311618, an HC trapper containing an adsorbent is arranged downstream of the catalyst device in parallel with the main exhaust pipe, and a bypass passage including the trapper and a main exhaust are provided. Each pipe is provided with a flow path switching valve. Then, immediately after the engine is started, the valve is operated for a specific time to allow the exhaust gas to flow into the bypass passage, during which cold HC is adsorbed by the trapper. At the time of high temperature when cold HC is desorbed from the adsorbent, the above-mentioned valve allows exhaust gas to flow into the main exhaust pipe, and at this time, the desorption pipe that connects the trapper downstream side and the engine intake pipe with the intake The negative pressure of the pipe is applied, and the desorbed HC is sucked into the intake pipe and burned again in the engine.

Further, in Japanese Patent Laid-Open No. 4-311618,
An example is also described in which the desorbed HC is forcibly returned to the upstream side of the catalyst by using a suction pump. However, in the above-mentioned conventional cold HC adsorption technique, when the HC trapper is arranged on the upstream side of the catalyst device, the heat resistance of the adsorbent becomes a problem.
Therefore, in JP-A-2-135126, a zeolite adsorbent having high heat resistance is used. However, the adsorbent generally has a higher adsorbing performance at lower temperatures, and even with zeolite, HC is desorbed before the catalyst reaches the activation temperature. Therefore, the adsorbed HC is released to the atmosphere without being purified. Also,
When the HC trapper is arranged upstream of the catalyst device, the heat capacity of the catalyst itself becomes large, so that there is a problem that the activation of the catalyst, that is, the time until the catalyst reaches the activation temperature is delayed.

On the other hand, JP-A-4-17710 and JP-A-4-311 in which an HC trapper is arranged on the downstream side of the catalyst device.
No. 618 solves the above problems regarding cold HC adsorption performance and catalyst activation. However, in heat conduction from the bypass passage, heat transfer to the adsorbent is slow and H
Desorption of C takes a long time, and sometimes the desorption is not completed. When this state is repeated, HC is accumulated in the adsorbent, and eventually the adsorbent breaks through and cannot adsorb HC.
Causes problems such as. Further, when the exhaust gas containing HC is returned to the intake pipe, the air-fuel ratio control of the engine is deviated, which may adversely affect fuel economy, exhaust gas purification, and drivability.

[0007]

In view of the above circumstances, the present invention prevents the release of harmful components in the exhaust gas when the engine is cold, and the HC adsorbed by the adsorbent when the engine is warmed up.
It is an object of the present invention to provide an exhaust gas purifying apparatus that desorbs HC in a short time, recirculates the desorbed HC to a catalyst device, and minimizes the adverse effect on engine control due to this reflux.

[0008]

Therefore, according to the present invention, there is provided a catalyst device arranged in an exhaust pipe of an internal combustion engine, and an adsorption device arranged downstream of the catalyst device for adsorbing harmful components of exhaust gas of the internal combustion engine. Body, the exhaust gas harmful components adsorbed by the adsorbent, a recirculation means for recirculating the exhaust gas to the upstream side of the catalyst device, and if the exhaust gas temperature of the internal combustion engine is below a predetermined temperature, the exhaust gas is mainly When the exhaust gas harmful components are adsorbed by passing through the adsorbent, and when the exhaust gas temperature of the internal combustion engine is equal to or higher than a predetermined value, the flow of the exhaust gas of the internal combustion engine mainly prevents the adsorbent from passing the exhaust gas. In the exhaust gas purifying device, the exhaust gas purifying device is configured to expose the adsorbent to the exhaust gas when the exhaust gas temperature of the internal combustion engine is equal to or higher than a predetermined value.

In the exhaust pipe of the internal combustion engine, a flow path is divided into two by a partition wall having an opening formed therein, and the adsorbent is provided in one of the flow paths, and at the opening, Provided is an exhaust gas purification device in which at least a part of a side surface of an adsorbent is exposed to the other flow path.
Further, provided on the entire circumference of the adsorbent except for a portion exposed to the other flow path, while holding and fixing the adsorbent to the exhaust pipe, between the adsorbent and the exhaust pipe There is provided an exhaust gas purifying device provided with a holding member made of an airtight material for preventing the inflow of the exhaust gas.

Further, the switching means provides the exhaust gas purifying device provided only on the downstream side of the adsorbent. Further, there is provided an exhaust gas purifying device in which the recirculation means is provided with a one-way valve for controlling the exhaust gas harmful component only on the upstream side. Further, there is provided an exhaust gas purification device in which the outer peripheral surface of the adsorbent is exposed to the exhaust gas of the internal combustion engine when the temperature of the exhaust gas of the internal combustion engine is above a predetermined level.

Further, a through hole is formed substantially in the center of the adsorbent, and when the temperature of the exhaust gas of the internal combustion engine is higher than a predetermined value, the exhaust gas of the internal combustion engine passes through the through hole. Provide a purification device. Furthermore, in the adsorbent, when the exhaust gas temperature of the internal combustion engine is equal to or higher than a predetermined value,
Provided is an exhaust gas purifying device provided with a heat absorbing means exposed to the exhaust gas.

[0012]

According to the present invention, when the exhaust gas temperature of the internal combustion engine is lower than the predetermined value, the adsorbent adsorbs the harmful components in the exhaust gas. Then, when the temperature of the exhaust gas of the internal combustion engine reaches or exceeds the predetermined value, the switching unit discharges the exhaust gas without passing through the adsorbent. At this time, the adsorbent is exposed to the exhaust gas. Therefore, in the present invention, the adsorbent is positively heated by the exhaust gas, and the desorption of harmful components of the adsorbed exhaust gas is promoted. The desorbed harmful component is refluxed to the upstream of the catalyst device by the reflux means. Then, it is purified by the catalyst device.

Further, by forming the opening in the partition wall, the adsorbent can be directly exposed to the exhaust gas discharged from the internal combustion engine, and the harmful components can be desorbed from the adsorbent more efficiently. it can. Further, since the holding member that supports the adsorbent to the exhaust pipe is made of an airtight material and is provided on the entire circumference of the adsorbent, even if the adsorbent adsorbs the harmful components, Even when desorbed, harmful components can be efficiently adsorbed or desorbed without leaking harmful components from the adsorbent to the exhaust pipe.

Further, since this holding member is provided in a portion other than the portion exposed to the other flow path of the adsorbent, the harmful components can be efficiently desorbed from the adsorbent. Further, since the switching means is provided only on the downstream side, when the exhaust gas temperature of the internal combustion engine is equal to or higher than the predetermined value, the exhaust gas is constantly made to collide with the upstream end surface of the adsorbent, and the heat of the exhaust gas causes more adsorption. It can promote the elimination of the body.

Further, by providing the one-way valve in the reflux means, the harmful components adsorbed on the adsorbent can be reliably recirculated to the upstream side of the catalyst device. Further, when the temperature of the exhaust gas of the internal combustion engine is equal to or higher than a predetermined value, the outer peripheral surface of the adsorbent is exposed to the exhaust gas, so that the adsorbed harmful components that have been adsorbed can be efficiently desorbed.

Further, when the temperature of the exhaust gas of the internal combustion engine is higher than a predetermined value, the exhaust gas passes through the through hole provided in the adsorbent body. It is possible to effectively desorb the adsorbed harmful components. Further, since the adsorbent is provided with the heat absorbing means that is exposed to the exhaust gas, it is possible to further desorb the harmful components from the adsorbent.

[0017]

【Example】

[First Embodiment] As shown in FIG. 1, an exhaust manifold 31 is provided in an exhaust pipe 3 of an engine 1 for an automobile, which is an internal combustion engine.
A catalyst device 4 is provided immediately after the. Further, a large diameter portion 32 is provided in the downstream of the catalyst device 4, and the honeycomb body 5 as an adsorbent is housed in the large diameter portion 32.

The honeycomb body 5 is made of a ceramic such as stainless steel or cordierite, has a semicylindrical shape matching the large diameter portion 32, and has a large number of parallel through holes 51 as shown in FIG. Further, on the surface of the through hole 51, an adsorbent carrying layer 5a carrying a zeolite adsorbent capable of adsorbing HC gas which is a harmful component of the exhaust gas from the engine 1 is formed.

The honeycomb body 5 and the flow path 34 are provided with partition walls 33.
Separated and held by. As shown in FIG. 2, the partition wall 33 is provided with a hole 33a. In front of the honeycomb body 5, a straightening plate 35 formed by extending the partition 33 is provided. This rectifying plate 3
By providing 5, the flow velocity distribution of the exhaust gas can be made uniform when the exhaust gas flows through the honeycomb body 5,
The adsorption efficiency can be increased.

However, the partition wall 33 and the flow regulating plate 35 may have an integral structure or may be separated. In addition, the circulation flow path pipe 6a is branched from the vicinity of the rear end of the honeycomb body 5 of the exhaust pipe 3. The flow passage pipe 6a is connected to a circulation flow passage pipe 6b communicating with the exhaust manifold 31 via a reed valve 7 including a one-way valve 7a and an on-off valve 7b, which will be described later, as a flow adjusting means for controlling the flow in the pipe in one direction. And constitutes a reflux means.

Immediately after the rear end of the adsorbent carrying layer 5a of the honeycomb body 5, an exhaust gas passage switching valve 8 as a switching means is arranged. Here, the structure for holding the large-diameter portion 32 of the honeycomb body 5 will be described with reference to FIGS. 2 to 4. A supporting member 301, which is a holding member made of an airtight material, is elastic over the entire circumference of the front end portion and the rear end portion of the honeycomb body 5,
302 is provided. This support 301 has holes 33
It is provided so as not to cover the opening area of a. The support member 301 holds the honeycomb body 5 between the large diameter portion 32 and the partition wall 33.

Further, as shown in FIGS. 3 (a) and 3 (b), a step 321 is formed at a portion of the large-diameter portion 32 which comes into contact with the front end portion of the honeycomb body 5, and the honeycomb body 5 has an engine or the like. It is prevented from moving to the upstream side of the exhaust pipe due to vibration from the outside. On the upstream side of the exhaust pipe of the honeycomb body 5, in this embodiment, the step 321 prevents the honeycomb body 5 from moving on the upstream side. However, a stopper plate, a stopper pin, or the like may be provided in the large-diameter portion 32. The same effect can be obtained.

Further, as shown in FIG. 4, the rear end portion of the honeycomb body 5 is in contact with the shaft case 81 which is the shaft of the exhaust gas passage switching valve 8 attached to the partition wall 33. Due to the contact between the honeycomb body 5 and the shaft case 81, the honeycomb body 5 also functions as a stopper that does not move to the downstream side of the exhaust pipe even when the honeycomb body 5 receives vibration from the outside such as an engine. Again, in order to prevent the honeycomb body 5 from moving to the downstream side of the exhaust pipe, a step may be provided in the large diameter portion as shown in FIG. 3, or a stopper plate, a stopper pin or the like may be attached to the large diameter portion. May be.

As described above, the honeycomb body 5 has the large diameter portion 32.
Will be retained within. Catalyst device 4 and honeycomb body 5
And the timing at which the catalyst device 4 is heated by the exhaust gas to reach the activation temperature and the timing at which the adsorbent carried on the honeycomb body 5 is heated and loses the adsorption function are substantially equal to each other. It The flow path switching valve 8 is connected to the actuator 9 via the shaft 91.

The actuator 9 is connected to the surge tank 2 upstream of the engine 1 by intake pipes 10a and 10b for supplying a negative pressure for operating the actuator 9.
A solenoid valve 11 is provided between the intake pipes 10a and 10b. The reed valve 7 has a one-way valve 7a and an opening / closing valve 7b. The one-way valve 7a allows only the fluid to flow from the side between the circulation channels 6a. The on-off valve 7b is adapted to be operated by a diaphragm or the like that operates under negative pressure.
The on-off valve 7b is provided with intake pipes 12a, 12 which supply negative pressure to the on-off valve
By b, it is made to communicate with the intake pipe 10b which connects the solenoid valve 11 and the surge tank 2. In addition, the intake pipe 12
A solenoid valve 13 is provided between a and 12b.

Reference numeral 14 is a control means incorporated in the microcomputer, which receives signals from the engine 1 and the exhaust temperature sensor 15 and controls the opening and closing of the solenoid valves 11 and 13 in accordance with the operating state.
Thereby, the switching valve 8 and the open / close valve 7b are controlled. Next, the operation of the exhaust gas purification apparatus of this embodiment is
A description will be given using the flowchart of FIG. 5 together with FIG.

When the engine is started (IG.ON), the solenoid valve 11 is opened by the control means 14 and the intake pipes 10a, 10
b communicates. As a result, the negative pressure of the surge tank 2 acts on the actuator 9 via the intake pipes 10a and 10b to pull the shaft 91, and the switching valve 8 becomes the position shown by the broken line (valve 8 closed). Immediately after the engine 1 is started, the exhaust gas temperature is low, and the engine 1 discharges exhaust gas containing a large amount of cold HC. While the exhaust gas temperature is low, the catalyst does not reach the activation temperature, so that the cold HC is hardly purified by the catalyst device 4 and flows through the exhaust pipe 3. At this time, the exhaust gas temperature is monitored by the exhaust temperature sensor 15.

This exhaust gas flow flows through the adsorbent-free layer 5c that does not support zeolite and the adsorbent-supporting layer 5a that supports zeolite in the honeycomb body 5, cold HC is adsorbed by the adsorbent, and cold HC is absorbed. The removed exhaust gas is discharged into the atmosphere through a muffler (not shown). At this time, since the rectifying plate 35 rectifies the flow of the exhaust gas, the exhaust gas has a uniform flow velocity distribution and flows in the honeycomb body 5.

Further, since the supporting member 301 is provided on the entire circumference of the honeycomb body 5 and is made of an airtight material, the exhaust gas flow passes through the gap 34 between the partition wall 33 and the honeycomb body 5 into the flow passage 34. It doesn't flow to. Therefore, the honeycomb body 5 can obtain high adsorption efficiency of harmful components of exhaust gas. For a predetermined time (t) when the engine 1 warms up and the exhaust gas temperature exceeds the HC adsorbable temperature of the intake agent
When a) has passed (t> ta), the electromagnetic valve 11 is closed by the signal from the control means 14 (valve 11 closed). As a result, the supply of negative pressure to the actuator 9 is cut off, and the actuator 9 is driven by the elasticity of a built-in spring to
Press 1. Therefore, the switching valve 8 is in the position shown by the solid line (the valve 8 is open), the flow path of the exhaust gas is switched, and the exhaust gas flows through the flow path 34 where the honeycomb body 5 does not exist. At this time, the catalyst reaches the activation temperature, HC in the exhaust gas is purified by the catalyst device 4,
Exhaust gas containing almost no HC is released into the atmosphere through the flow path 34.

Immediately after the solenoid valve 11 is closed, the control means 1
The solenoid valve 13 is opened by the signal from 4 (valve 13 open).
As a result, the suction pipe 10b and the suction pipe 12a communicate with each other, negative pressure is supplied from the surge tank 2 to the opening / closing valve 7b, and the opening / closing valve 7b
b is opened (valve 7b is opened). On the other hand, on the side surface of the honeycomb body 5, the exhaust gas that has already become hot flows through the flow path 34. This high-temperature exhaust gas is exposed to the exhaust gas through the holes 33 a of the partition walls 33. That is,
The honeycomb body 5 is in contact with the adsorbent carrying layer 5a. Therefore, the heat of the exhaust gas is absorbed by the adsorbent support layer 5a.
The temperature of the adsorbent rises and the desorption of HC is promoted.

Further, since the support members 301 and 302 are provided, the HC that is detached from the honeycomb body 5 is separated by the partition walls 3
3 does not leak into the flow path 34 through the hole 33a. Furthermore, since the support members 301 and 302 are provided on the honeycomb 5 so as not to cover the holes 33a, the heat of the exhaust gas is not generated by the holes 33a.
It can be satisfactorily transmitted to the adsorbent support layer 5a via a.

At this time, since the opening / closing valve 7b is opened as described above, the exhaust pulsation generated in the exhaust manifold 31 intermittently opens the one-way valve 7a via the circulation flow pipe 6b. Thereby, the adsorbent supporting layer 5 of the honeycomb body 5
The HC desorbed from the adsorbent of a flows into the exhaust manifold 31 via the circulation flow path pipes 6a and 6b. Then, it is purified by the catalyst device 4 together with HC in the exhaust gas from the engine 1.

After the switching valve 8 is switched to the open position (shown by the solid line) and the HC desorption / purification process is started, when the time (tb) for completing the desorption of HC has elapsed [t> (ta + tb)],
The solenoid valve 13 and the on-off valve 7b are controlled by a signal from the control means 14.
Are closed (valve 13 closed, valve 7b closed). In the above embodiment, the timing of switching the switching valve 8 to the HC desorption / purification process side (solid line position) by closing the solenoid valve 11 by the signal from the control means 14 is set to the predetermined time, but the exhaust gas temperature May be the time when the temperature reaches a predetermined high temperature.

Therefore, in the exhaust gas purifying apparatus of this embodiment, the emission of cold HC is prevented even when the engine is cold until the catalyst reaches the activation temperature. In this device, in particular, since the adsorbent-carrying layer 5a for adsorbing cold HC to the adsorbent and the main exhaust gas flow path 34 are formed so as to be in direct contact with each other, the adsorbent is removed during the HC desorption and purification process. It is heated by the heat of the high-temperature exhaust gas, and HC is effectively desorbed and purified.

Further, since the desorbed HC is recirculated to the exhaust pipe 3 upstream of the catalyst device 4, the adverse effect on the engine control due to the recirculation of HC can be reduced. In the present embodiment, the honeycomb body 5 has a semi-cylindrical shape,
The honeycomb body 5 may have an elliptical shape or a rectangular shape in accordance with the large diameter portion 32. [Second Embodiment] A second embodiment of the present invention will be described with reference to FIG.
It is shown in the configuration diagram of FIG.

FIG. 6 (b) shows a cross section taken along the line AA of FIG. 6 (a). In this embodiment, the honeycomb body 5 is arranged at the center of the adsorption cylinder 50, and exhaust gas flows through the outer periphery of the honeycomb body 5. The operation of this embodiment is similar to that of the first embodiment. The difference from the first embodiment is the flow of exhaust gas to the honeycomb body 5.

That is, in this embodiment, as compared with the first embodiment, the HC
High temperature exhaust gas and adsorbent support layer 5a
Since the entire outer peripheral area of the above contacts, the desorption is further promoted as compared with the first embodiment, and there is an advantage that a series of control can be completed in a shorter time. The position of the honeycomb body 5 may be eccentric instead of the center. [Third Embodiment] A third embodiment of the present invention will be described with reference to FIG.
It is shown in the configuration diagram of (b).

FIG. 7B shows a BB cross section of FIG. 7A. In this embodiment, the flow path 34a is provided as a through hole provided in the center of the adsorption cylinder 50, and exhaust gas flows through the through hole. The position of the flow path 34a may be eccentric instead of being in the center. The operation of this embodiment is similar to that of the first embodiment.

Compared to the first embodiment, this embodiment is more desorbed than the first embodiment because the hot exhaust gas and the entire inner peripheral area of the adsorbent support layer 5a are in contact with each other during desorption and purification of HC. Is promoted, and a series of controls can be completed in a shorter time. Moreover, it is not necessary to form a new flow path, and the entire structure can be downsized. [Fourth Embodiment] The fourth embodiment of the present invention is shown in the block diagram of FIG.

In this embodiment, for example, the fin 33b made of stainless steel is projected into the flow path 34. The operation of this embodiment is similar to that of the first embodiment. Compared to the first embodiment, this embodiment is different from the first embodiment in that the exhaust gas of high temperature and the fins 33b protruding from the adsorbent carrying layer 5a are discharged.
Since there is contact, the desorption is further promoted as compared with the first embodiment, and there is an advantage that a series of control can be completed in a shorter time.

In the present invention, the direction of the fins 33b does not necessarily have to be the vertical direction and may be oblique.

[0042]

By adopting the present invention, the harmful components in the exhaust gas are prevented from being released when the engine is cold, and the HC adsorbed on the adsorbent is desorbed in a short time when the engine is warmed up. It is possible to provide an exhaust gas purifying apparatus in which the generated HC is recirculated to the catalyst device and the adverse effect of the recirculation on engine control is minimized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment device of the present invention.

[Fig. 2] Fig. 2 is a perspective view of a honeycomb body in which an adsorbent is supported on a half-section portion used in the apparatus of the first embodiment, and partition walls.

FIG. 3 is an enlarged front end portion of the honeycomb body used in the first embodiment.

FIG. 4 is a rear end enlarged portion of the honeycomb body used in the first embodiment.

FIG. 5 is a flowchart showing the operation of the first embodiment device.

6A and 6B are configuration diagrams of a second embodiment device of the present invention.

7A and 7B are configuration diagrams of a third embodiment device of the present invention.

FIG. 8 is a configuration diagram of a fourth embodiment device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine which is an internal combustion engine 3 Exhaust pipe 33 Partition wall 33a Partition hole 4 Catalytic device 5 Honeycomb bodies 6a, 6b Circulation flow path pipe 7a One-way valve (flow adjusting means) 8 Exhaust gas flow path switching valve 15 Exhaust temperature sensor 301, 302 Support material

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuji Mori 1-1, Showa-cho, Kariya city, Aichi Prefecture Nihon Denso Co., Ltd. (72) Inventor, Makoto Saito 1-1-1-1 Showa-cho, Kariya city, Aichi prefecture Nidec Incorporated (72) Inventor Takahiko Yamamoto 1-1-1, Showa-cho, Kariya city, Aichi Prefecture

Claims (8)

[Claims] 1. A catalyst device disposed in an exhaust pipe of an internal combustion engine, an adsorbent disposed downstream of the catalyst device to adsorb exhaust gas harmful components of the internal combustion engine, and adsorbed by the adsorbent. And a recirculation means for recirculating the exhaust gas harmful component to the upstream side of the catalyst device, and when the exhaust gas temperature of the internal combustion engine is below a predetermined level, the exhaust gas mainly passes through the adsorbent and the exhaust gas harmful component While adsorbing
When the exhaust gas temperature of the internal combustion engine is equal to or higher than a predetermined level, the exhaust gas purifying apparatus mainly includes a switching unit that switches a flow of the exhaust gas of the internal combustion engine so that the exhaust gas does not pass through the adsorbent. An exhaust gas purification device, wherein the adsorbent is exposed to the exhaust gas when the temperature of the exhaust gas of the engine is equal to or higher than a predetermined value. 2. The exhaust pipe of the internal combustion engine has a flow passage divided into two by a partition wall having an opening formed therein, and the adsorbent is provided in one of the flow passages, and at the opening, The exhaust gas purifying apparatus according to claim 1, wherein at least a part of a side surface of the adsorbent is exposed to the other flow path. 3. The adsorbent is provided on the entire circumference except the portion exposed to the other flow path, holds the adsorbent in the exhaust pipe, and fixes the adsorbent and the exhaust pipe. The exhaust gas purifying apparatus according to claim 2, further comprising a holding member made of an airtight material for preventing the exhaust gas from flowing into the space. 4. The exhaust gas purifying apparatus according to claim 1, wherein the switching means is provided only on the downstream side of the adsorbent. 5. The exhaust gas purifying apparatus according to claim 1, wherein the recirculation means is provided with a one-way valve that controls the exhaust gas harmful components only on the upstream side. 6. The exhaust gas purifying apparatus according to claim 1, wherein when the exhaust gas temperature of the internal combustion engine is equal to or higher than a predetermined value, the outer peripheral surface of the adsorbent is exposed to the exhaust gas of the internal combustion engine. 7. A through hole is formed in a substantially central portion of the adsorbent, and when the exhaust gas temperature of the internal combustion engine is higher than or equal to a predetermined value, the exhaust gas of the internal combustion engine is prevented from passing through the through hole. The exhaust gas purifying apparatus according to claim 1, which is characterized in that. 8. The exhaust gas purifier according to claim 1, wherein the adsorbent is provided with a heat absorbing means that is exposed to the exhaust gas when the exhaust gas temperature of the internal combustion engine is equal to or higher than a predetermined value. apparatus.