JPH08165920A - Exhaust emission control device - Google Patents

Abstract

PURPOSE: To improve the adsorption efficiency of HC to an adsorber in an exhaust emission control device having a switching valve for switching between a passage of an adsorber and an exhaust passage installed parallel thereto. CONSTITUTION: The expanding angle θ of an expanded pipe 31 positioned on the upstream side of an adsorber 5 is set within a range (50-80 degrees) as to cause one-sided wall surface separation. At the time of cold after the start of an engine 1, a switching valve 8 is operated to a broken line position to let exhaust gas flow through a passage 5a of an adsorber 5 side. At that time, a quick flow of exhaust gas is biased to the adsorber 5 side by one-sided wall surface separation to equalize the exhaust gas inflow speed to the adsorber 5, so that the adsorption efficiency of HC or the like can be improved. After warming-up of the engine 1, the switching valve 8 is switched to the solid line position for opening the exhaust passage 34 side so that exhaust gas flows through the exhaust passage 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an engine (internal combustion engine) mounted on an automobile or the like.

[0002]

2. Description of the Related Art As one method of purifying exhaust gas of an automobile engine, an exhaust gas purifying apparatus using a carrier carrying a precious metal (platinum, rhodium, etc.) as a catalyst is known. Purification of a hydrocarbon compound (hereinafter abbreviated as HC) by this method generally requires a catalyst activation temperature of 350 ° C. or higher.

However, since the catalyst has not reached the catalyst activation temperature immediately after the engine is started, the HC
The problem is that purification is rarely performed. Therefore, in order to solve the above problem, a catalyst device is provided in the exhaust system of the engine, and HC (hereinafter referred to as cold HC) exhausted during cold engine operation is adsorbed on the upstream side or the downstream side thereof. Purification devices equipped with an HC trapper containing an adsorbent have been proposed in JP-A-2-135126, JP-A-4-177710, JP-A-4-31618 and the like.

In the purifying device of the above-mentioned Japanese Patent Laid-Open No. 2-135126, an adsorbent device using a zeolite-based adsorbent is arranged on the upstream side of the catalyst device, and the adsorbent device and the catalyst device are used together to produce exhaust gas. Cold HC is adsorbed on the adsorbent at a low temperature, and HC desorbed from the adsorbent and exhaust HC from the engine are purified by a catalyst at a high exhaust gas temperature.

Further, the above-mentioned JP-A-4-17710,
In the purification device of Japanese Patent Laid-Open No. 4-311618, an HC trapper containing an adsorbent is arranged downstream of the catalyst device in parallel with the main exhaust pipe, and the bypass passage containing the HC trapper and the main exhaust pipe are respectively arranged. A flow path switching valve is provided. Then, immediately after the engine is started, the valve is operated for a predetermined time to allow exhaust gas to flow to the bypass passage,
Meanwhile, cold HC is adsorbed by the trapper. When the exhaust gas temperature rises and cold HC is desorbed from the adsorbent of the HC trapper after a lapse of a predetermined time after the engine is started, the valve is switched to a position where the exhaust gas flows through the main exhaust pipe. The negative pressure of the intake pipe of the engine is applied to the desorption pipe connecting the trapper downstream side and the engine intake pipe, and the desorbed HC is sucked into the intake pipe and burned again in the engine.

[0006]

However, among the above-mentioned conventional cold HC adsorption techniques, HC is provided upstream of the catalyst device.
In the case where the trapper is provided, the high temperature exhaust gas immediately after being discharged from the engine flows into the HC trapper, so that the heat resistance of the adsorbent becomes a problem. Therefore, JP-A-2-1351
In Japanese Patent No. 26, a zeolite adsorbent having high heat resistance is used. However, adsorbents generally have higher adsorbing performance at lower temperatures, and even with zeolite, the HC
Are desorbed, so that the problem arises that the adsorbed HC is released to the atmosphere without being purified.

Further, when the HC trapper is arranged upstream of the catalyst device, the HC trapper itself has a large heat capacity, 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-4-1, in which an HC trapper is provided on the downstream side of the catalyst device
In Japanese Patent No. 7710 and Japanese Patent Laid-Open No. 4-311618,
Regarding the adsorption performance of cold HC and the activation of the catalyst, the above problems are solved.

However, in both of the above publications, the velocity distribution of the exhaust gas flowing into the HC trapper is not considered at all, but according to the experiments conducted by the present inventors, the velocity of the exhaust gas flowing into the HC trapper. It has been found that the non-uniform distribution causes a problem that the HC adsorption efficiency of the adsorbent is significantly reduced. Therefore, in view of the above circumstances, the present invention provides an exhaust gas purifying apparatus that has an exhaust gas flow path switching unit that switches a flow path of an adsorption device and an exhaust flow path that forms a flow of exhaust gas that does not pass through the adsorption device. The exhaust gas flow path switching means can be installed at one location on the downstream side of the adsorption device to simplify the structure, and
It is an object of the present invention to provide an exhaust gas purifying device that can improve the adsorption efficiency of the adsorption device by devising the structure of the expansion pipe located upstream of the adsorption device to make the velocity distribution of the exhaust gas flowing into the adsorption device uniform. .

Another object of the present invention is to provide an exhaust gas purifying device which can be easily mounted on a vehicle.

[0010]

In order to achieve the above object, the present invention employs the following technical means. According to the invention of claim 1, the catalyst device (4) is arranged in the exhaust pipe (3) of the engine (1), and is arranged in the exhaust pipe (3) downstream of the catalyst device (4). An adsorbing device (5) carrying an adsorbent for adsorbing exhaust gas harmful components, and exhaust gas not passing through the adsorbing device (5) in the exhaust pipe (3) downstream of the catalyst device (4). An exhaust flow path (34) forming a flow, and a return flow path (6a, 6b) for returning the exhaust gas harmful components adsorbed by the adsorption device (5) to the upstream side of the catalyst device (4), An exhaust gas flow passage switching means (8) provided downstream of the adsorption device (5) and capable of selectively switching the flow of exhaust gas between the flow passage of the adsorption device (5) and the exhaust flow passage (34). ), And the exhaust pipe (3) provided upstream of the adsorption device (5) and the exhaust flow path (34). Is formed so as to enlarge the flow passage cross-sectional area than,
Exhaust gas is adsorbed to the adsorption device (5) or the exhaust flow path (3).
4) the expansion pipe (31) and the switching means (8), the exhaust gas is adsorbed (5) when the engine (1) is cold.
And a control means (10) for switching to a position where the exhaust gas is allowed to flow into the exhaust flow passage (34) when the engine (1) is warmed up, and the expansion pipe (31) is expanded. The angle (θ) is characteristic of the exhaust gas purifying device in which the flow of the exhaust gas inside is set in a range where the one-sided wall surface is separated.

According to a second aspect of the present invention, in the exhaust gas purifying apparatus according to the first aspect, the expansion angle of the expansion pipe (31) is set in the range of 50 to 80 degrees. . According to a third aspect of the invention, in the exhaust gas purifying apparatus according to the first or second aspect, the flow passage (5d) of the adsorption device (5) and the exhaust flow passage (34) are arranged adjacent to each other. The cross-sectional shape of the entire flow path, which is a combination of both flow paths (5d, 34), is elliptical.

According to a fourth aspect of the present invention, in the exhaust gas purifying apparatus according to the third aspect, the flow passage (5d) and the exhaust flow passage (34) of the adsorption device (5) have the elliptical shape. It is characterized in that they are arranged adjacent to each other in the axial direction. According to a fifth aspect of the present invention, in the exhaust gas purifying apparatus according to the third or fourth aspect, the ellipse-shaped major axis direction of the adsorption device (5) and the exhaust passage (34) is substantially horizontal. In this way, it is arranged below the vehicle body of the vehicle.

According to a sixth aspect of the present invention, in the exhaust gas purification device according to any one of the first to fifth aspects,
An actuator (9) for driving the switching means (8) by engine intake negative pressure, and an intake negative pressure introduction flow path (15) for introducing engine intake negative pressure to the actuator (9).
a, 15b) and the intake negative pressure introducing passages (15a, 15b)
b), an on-off valve (13) that is opened and closed by the control means (10), and the intake negative pressure introduction flow path (15)
a, 15b), and a one-way valve (14) for flowing fluid in only one direction from the actuator (9) to the engine intake side.

The reference numerals in parentheses of the above means indicate the correspondence with the concrete means described in the embodiments described later.

[0015]

According to the inventions of claims 1 to 6,
Since the above technical means is provided, during the cold after the engine is started, the exhaust gas flows from the catalyst device (4) to the adsorption device (5) by the flow passage switching action of the exhaust gas flow passage switching means (8). It is discharged via the path (5d). In this case, the catalytic device (4)
The HC in the exhaust gas that is not purified by is adsorbed by the adsorbent of the adsorption device 5.

On the other hand, after the engine is warmed up, the exhaust gas flow path switching means (8) switches the flow path so that the exhaust gas flows from the catalyst device (4) to the exhaust flow path (34) where the adsorption device (5) does not exist. ) Is released through. At this time, H in the exhaust gas
C is purified by the activated catalyst device (4) due to high temperature. In addition, H adsorbed by the adsorbent of the adsorption device (5)
C is desorbed, and the desorbed HC is recirculated to the upstream side of the catalyst device (4) from the reflux flow paths (6a, 6b), and the desorbed HC can be promptly purified by the catalyst device (4).

Moreover, since the expansion angle of the expansion pipe (31) located on the upstream side of the adsorption device (5) is set within the range in which the flow of exhaust gas inside the expansion pipe (31) causes single-sided wall separation, H
At the time of C adsorption, it becomes possible to bias the fast flow of exhaust gas in the flow path (5d) on the adsorption device (5) side, and as a result, the inflow speed of the exhaust gas flowing into the adsorption device (5) can be made uniform. The entire adsorption device can be effectively used for adsorbing HC, and the adsorption efficiency can be significantly improved.

When desorbing HC, the exhaust flow path (34)
Since the fast flow of exhaust gas can be biased to the side,
It is possible to suppress the generation of vortices on the upstream side of the adsorption device (5), so that the once adsorbed HC can be prevented from flowing out to the exhaust flow path (34) side, and the exhaust gas purification effect can be further enhanced. Further, an exhaust gas flow passage switching means (8) for switching the flow passage (5a) of the adsorption device (5) and the exhaust flow passage (34) forming a flow of exhaust gas that does not pass through the adsorption device (5). The structure can be simplified because it only has to be installed at one location on the downstream side of the adsorption device (5).

In addition to the above function and effect, in the invention according to claim 5, the adsorption device (5) and the exhaust passage (34) are
With the major axis direction of the ellipse being substantially horizontal,
Since it is arranged below the vehicle body (12) of the vehicle, the overall shape of the adsorption device (5) and the exhaust flow path (34) is flat in the vertical direction, and the height can be reduced, so that it can be mounted on the vehicle. Is easy.

According to a sixth aspect of the present invention, there is provided an actuator (9) for driving the switching means (8) by the engine intake negative pressure, and an intake air introducing the engine intake negative pressure to the actuator (9). Negative pressure introduction flow path (1
2a, 12b), an on-off valve (13) controlled to be opened and closed by the control means (10), and the actuator (9).
Since the one-way valve (14) that allows the fluid to flow only in one direction from the engine to the engine intake side is opened, the throttle valve (2b) of the engine (1) is opened and the intake negative pressure in the intake manifold (2a) is reduced. When the pressure decreases, the one-way valve (14) is closed to prevent the negative pressure in the actuator (9) from immediately decreasing.

Therefore, since a large negative pressure in the actuator (9) can be maintained, the switching means is displaced under the influence of exhaust pressure pulsation, vibration of the vehicle body, etc. when the engine intake negative pressure is reduced. Does not occur. Therefore, it is not necessary to set the actuator (9) to a large size so as to cope with a decrease in engine intake negative pressure, and the actuator (9) can be downsized, which is extremely advantageous for mounting on a vehicle. .

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to an exhaust gas purifying apparatus for an automobile engine, and a catalyst device 4 is provided at a position immediately after an exhaust manifold 2 in an exhaust pipe 3 of a gasoline engine 1 for an automobile. It is set up. This catalytic device 4 is
A honeycomb carrier made of cordierite carrying a three-way catalyst containing a noble metal such as platinum or rhodium as a main component is provided therein.

The exhaust pipe 3 is provided with an expansion pipe 31 downstream of the catalyst device 4 for expanding the flow passage cross-sectional area.
Elliptic cylindrical or cylindrical adsorption cylinder 5 formed continuously with
In 0, the adsorption device 5 having a honeycomb structure is housed. The adsorption device 5 has a honeycomb structure made of stainless steel or ceramic such as cordierite. Then, the suction device 5 is formed in a half cross-sectional shape of the suction cylinder 50 having an elliptic cylinder shape in this example, that is, a semi-elliptical cylinder shape that matches the suction cylinder 50. The suction device 5 is arranged such that the flat surface of the semi-elliptical cylinder shape faces the center side of the suction cylinder 50.

This suction device 5 has a large number of parallel through holes 51.
The zeolite-based adsorbent is supported on the adsorbent-supporting layer 5a formed over the entire portion other than the upstream end thereof. Here, an adsorbent-free layer 5b having a predetermined width is provided on the upstream end side of the adsorption device 5. Also,
An exhaust gas flow passage switching valve 8 is provided immediately after the downstream end (rear end) of the adsorbent carrying layer 5a of the adsorption device 5. This switching valve 8
Is operated to open and close around the fulcrum 8a, and the flow path 5d of the adsorption device 5 having the honeycomb structure and the flow path 5d
Is opened and closed by switching to and from the exhaust passage 34 formed adjacent to the side of the.

As shown in FIG. 2, the expanding tube 31 has the following structure.
In this example, the cross section has an elliptical cross section, and the long axis direction of the cross section is divided into two by a plate-like partition wall 33.
The flow path 5d of the adsorption device 5 is formed on one side 31a of the two divided flow paths, and the exhaust flow path 34 is formed on the other flow path 31b side. Further, the spread angle θ of the expansion tube 31
(In the case of the elliptical shape in FIG. 2, the spread angle in the long axis direction of the ellipse) is set to an angle at which the one-sided wall surface peeling state shown in FIG. 3C occurs. Specifically, the angle θ at which this single-sided wall surface peeling state occurs is in the range of 50 degrees to 80 degrees. By setting the spread angle θ of the expansion tube 31 as described above, the flow velocity distribution of the exhaust gas in the adsorption device 5 can be made uniform when the exhaust gas flows into the adsorption device 5.

On the other hand, the distance between the catalyst device 4 and the adsorption device 5 depends on the timing at which the catalyst device 4 is heated by the exhaust gas and reaches the activation temperature, and the adsorbent carried on the adsorption device 5 is heated. The distance is set so as to almost coincide with the timing of losing the suction function. That is, the temperature at which the adsorbent carried by the adsorption device 5 loses its adsorption function from the catalyst activation temperature (350 ° C.) of the catalyst device 4 (in other words, the H
Since the C desorption start temperature is lower at 100 ° C. to 200 ° C., by setting the adsorption device 5 at a predetermined distance downstream from the catalyst device 4, both timings can be matched.

The adsorbing device 5 has the plate-shaped partition 33 between the adsorbing device 5 and the exhaust passage 34.
Is separated from the exhaust passage 34, and is pressed and held by the adsorption cylinder 50. It should be noted that the partition wall 33 is provided with a hole (not shown) so that the exhaust gas in the exhaust passage 34 can directly contact the adsorption device 5 through the hole.

On the other hand, the reflux flow passage 6a branches from a position close to the downstream end of the adsorption device 5 and upstream from the switching valve 8, and this flow passage 6a passes through the reed valve 7 to the exhaust manifold 2. It is connected to the recirculating flow path 6b which communicates. The reed valve 7 constitutes a flow adjusting means for controlling the flow of the flow paths 6a and 6b in only one direction, that is, one direction from the downstream end of the adsorption device 5 toward the exhaust manifold 2 side, and the one-way described later. It comprises a valve 7a and an on-off valve 7b.

The switching valve 8 is driven by an actuator 9 installed on the outer surface of the adsorption cylinder 50 via an arm 9a, a link mechanism (not shown) and the like. In this example, the actuator 9 is composed of a diaphragm and an electromagnetic valve that connects and disconnects the engine intake negative pressure that operates the diaphragm. The above-described one-way valve 7a of the reed valve 7 operates by the differential pressure of the exhaust pulsation on the upstream side of the catalyst device 4 and the downstream side of the adsorption device 5, so that the fluid flowing from the reflux flow passage 6a side to the reflux flow passage 6b side is discharged. Only distribution is allowed.
The on-off valve 7b includes a diaphragm that drives the valve body,
It is composed of an electromagnetic valve that connects and disconnects an engine intake negative pressure that operates this diaphragm.

Reference numeral 10 is a control device (control means) having a built-in microcomputer, which receives signals from the engine 1 and the exhaust temperature sensor 11 and opens and closes the open / close valve 7 according to the operating state of the engine 1.
b and the solenoid valve of the actuator 9 are controlled to be opened and closed, and thereby the switching valve 8 and the on-off valve 7b are controlled. Next, the operation of the apparatus of this embodiment having the above configuration will be described. FIG. 4 is a flow chart for explaining the operation. When the ignition switch of the engine 1 is turned on and the engine 1 is started, the microcomputer of the control device 10 is started (step S1), and then the initialization process (S).
After step 2), in S3, the control device 10 closes the on-off valve 7b and actuates the actuator 9 to rotate the switching valve 8 to the closed position shown by the broken line via the arm 9a. As a result, the exhaust passage 34 is closed and the passage 5d of the adsorption device 5 is opened.

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. Since the catalyst has not reached the activation temperature while the exhaust gas temperature is low, the cold HC flows through the exhaust pipe 3 without being substantially purified by the catalyst device 4. At this time, the exhaust gas temperature is detected by the exhaust temperature sensor 11. This exhaust gas flow does not flow to the exhaust flow path (main flow path) 34 side due to the closing of the switching valve 8, but flows to the flow path 5d of the adsorption device 5. In that case, first, it passes through the adsorbent-free layer 5b which does not support zeolite, and then flows through the adsorbent-supporting layer 5a which supports zeolite, where cold HC is adsorbed by the adsorbent.

Then, the exhaust gas from which the cold HC has been removed is discharged into the atmosphere through a muffler (not shown). At this time, the spread angle θ of the expansion tube 31 is set as shown in FIG.
The angle (θ = 50-
(80 degrees), the exhaust gas has a uniform flow velocity distribution and flows into the adsorption device 5, so that the adsorption device 5
The cold HC is uniformly adsorbed on the entire honeycomb carrier, and the adsorption efficiency is improved.

Incidentally, FIGS. 3A and 3B show the case where θ is smaller than the above angle range, and FIG. 3D shows the case where θ is larger than the above angle range. ),
In any of the flow configurations shown in (d), since it is not possible to bias the fast flow only to the flow passage 31a on one side of the expansion tube 31, the inside of the adsorption device 5 installed downstream of the flow passage 31a on this one side is not allowed. The flow velocity distribution of the inflowing exhaust gas becomes uneven.

Next, when the engine 1 is warmed up and a predetermined time (ta) until the exhaust gas temperature exceeds the HC adsorbable temperature of the adsorbent has passed (t> ta), the determination of S4 in FIG. 4 is made. If YES, the process proceeds to S5. As a result, the actuator 9 is actuated by a signal from the control device 10, the actuator 9 rotates the switching valve 8 counterclockwise via the arm 9a, moves to the valve opening position shown by the solid line, and the exhaust flow The path (main flow path) 34 is opened. Therefore, the exhaust gas mainly flows through the exhaust flow path 34 side where the flow paths are switched and the adsorption device 5 does not exist. At this time, since the catalyst has reached the activation temperature, the HC in the exhaust gas is purified by the catalyst device 4,
Exhaust gas containing almost no gas is discharged into the atmosphere through the exhaust flow path 34.

Immediately after the switching valve 8 is opened in step S5, the on-off valve 7b is opened by a signal from the control device 10 in step S6. On the other hand, on the side surface of the adsorption device 5, the exhaust gas that has already become hot flows through the exhaust passage 34. This high-temperature exhaust gas is in contact with the adsorbent support layer 5a of the adsorption device 5 through the holes of the partition wall 33. for that reason,
The heat of the exhaust gas is satisfactorily transferred to the adsorbent-supporting layer 5a and the adsorbent is quickly heated to promote desorption of HC.

At this time, since the on-off valve 7b is opened as described above, the exhaust gas pulsating pressure generated in the exhaust manifold 31 is applied to the back surface of the one-way valve 7a via the recirculation passage 6b. Further, the pulsating pressure of exhaust gas generated downstream of the adsorption device 5 is applied to the surface of the one-way valve 7a via the recirculation flow path 6a to intermittently open the one-way valve 7a. As a result, the HC desorbed from the adsorbent of the adsorbent-supporting layer 5a of the adsorber 5 passes through the return flow paths 6a and 6b, and then the exhaust manifold 2
Quickly flows into. Then, it is purified by the catalyst device 4 together with HC in the exhaust gas from the engine 1.

As described above, when desorbing HC, the flow of the exhaust gas passing through the adsorption device 5 becomes very small, so that the HC once adsorbed may be dragged out to the upstream side of the adsorption device 5. However, in this example, since the adsorbent-free layer 5c is formed on the upstream side of the adsorption device 5, the adsorption HC of the adsorption device 5 is prevented from flowing out to the exhaust flow path 34 side.

Even when the HC is desorbed, the exhaust gas flow is separated from the one-sided wall surface, and the exhaust passage 3
Since the fast flow of the exhaust gas is biased to the 4 side, it is possible to suppress the generation of the swirl of the exhaust gas in the upstream portion of the adsorption device 5. Therefore, it is possible to prevent the problem that the adsorbed HC is dragged to the exhaust flow path 34 side by this vortex. From the above,
The HC desorbed from the adsorption device 5 is surely returned to the reflux flow path 6a,
Since it rapidly flows into the exhaust manifold 2 via 6b and can be purified by the catalyst device 4, the purification efficiency of HC can be further improved.

Further, since the desorbed HC is recirculated to the exhaust manifold 2 side of the engine 1 and is not recirculated to the intake manifold 2a, the influence of the recirculated desorbed HC on the engine control can be minimized. On the other hand, after the switching valve 8 is switched to the open position (shown by the solid line) to enter the HC desorption purification process, H
When the time (tb) at which desorption of C is completed elapses, [t>
(Ta + tb)], the determination in S7 is YES, the process proceeds to S8, and the opening / closing valve 7b is closed by a signal from the control device 10.

In the above embodiment, the timing of switching the switching valve 8 to the HC desorption / cleaning stroke side (the valve opening position indicated by the solid line) by the signal from the control unit 10 is set to be after a predetermined time has elapsed from the engine start. Instead of determining the elapse of this predetermined time, it may be the time when the exhaust gas temperature reaches a predetermined high temperature. In the above embodiment, the reed valve 7 is a one-way valve 7.
Although it is configured to have both a and the on-off valve 7b, the one-way valve 7a may be used alone.

By the way, in the exhaust gas purifying apparatus of this embodiment, cold HC is adsorbed by the adsorbing apparatus 5 even when the engine is cold until the catalyst reaches the activation temperature.
Is prevented from being released into the atmosphere. Further, particularly in the present device, when the adsorbed HC is desorbed, the one-way valve 7 is operated by the pulsating pressure of the exhaust gas applied to the front and back surfaces of the one-way valve 7a.
a is intermittently opened to release the desorbed HC from the reflux flow path 6a,
It is possible to effectively circulate and purify HC by refluxing to the upstream side of the catalyst device 4 through 6b.

Next, the apparatus of the above-mentioned embodiment is applied to a vehicle (automobile).
The specific points to be considered for mounting on the board are described below. FIG. 5 shows a state in which a suction cylinder 50 portion, which is an essential part of the present invention, is mounted on a vehicle. The suction cylinder 50 is designed so that the major axis direction of the ellipse of its cross section is substantially horizontal. It is mounted below the concave portion 12a of 12 (under the vehicle floor). Further, the arm 9a of the actuator 9 is formed of a metal plate material as shown in the figure, and is bent downward from the switching valve 8 side connecting portion in the upper part of the adsorption cylinder 50 so that the actuator 9 is positioned above the adsorption cylinder 50. It doesn't stick out.

By adopting such a mounting layout, the overall height of the suction cylinder 50 portion becomes small, and mounting on a vehicle becomes easy. Also, the arm 9a of the actuator 9
Is arranged on the upper side of the adsorption cylinder 50 as shown in the figure, it is possible to greatly reduce the collision of flying stones with the arm 9a during traveling of the vehicle. it can.

In FIG. 5, the adsorption device 5 is arranged on the left side of the adsorption cylinder 50 in the drawing, and the exhaust passage 3 is disposed on the right side of the drawing.
4 are arranged. And 50a is an exhaust outlet pipe on the downstream side of the switching valve 8. FIG. 6 shows the arrangement positions of the actuator 9 and the return flow path 6a.
Since a is arranged close to each other, it is possible to reduce the installation space for both 9 and 6a.

Further, as shown in FIG. 6, the suction cylinder 5
Since a slope 50b is formed at the end of the exhaust gas on the downstream side of the exhaust gas 0, and the slopes 9b and 6a are arranged close to the slope 50b, the length of the adsorption cylinder 50 in the exhaust flow direction (the horizontal direction in FIG. 6). (Length) can be shortened, and mounting on a vehicle becomes easier. FIG. 7 shows another embodiment of the present invention, in which the actuator 9 for driving the exhaust gas flow path switching valve 8 is connected to the engine 1
When the actuator 9 is composed of the diaphragm 9b which is operated by the intake negative pressure, the actuator 9 is designed to be downsized.

That is, as shown in FIG. 7, the intake negative pressure introducing pipe 15a connected to the pressure chamber 9c of the actuator 9 is shown.
And the intake manifold (surge tank) 2a of the engine 1
Between the intake negative pressure introducing pipe 15b connected to the control valve 10 and the on-off valve (electromagnetic valve) 13 controlled by the control device 10, and a one-way valve for flowing the fluid from the actuator 9 to the intake side of the engine only in one direction. 14 are arranged in series.

The on-off valve 13 is the intake negative pressure introducing pipe 15
opening and closing of the passage between a and 15b, and the intake negative pressure introducing pipe 15a
This is a three-way valve type that opens and closes between the air vent and an atmosphere opening port (not shown). The operation according to the embodiment of FIG. 7 is also the same as that shown in FIG. 4. Immediately after the engine 1 is started, the on-off valve 13 is energized from the control device 10 in step S3 of FIG. Negative pressure introducing pipe 15a, 1
Connect between 5b. As a result, the intake negative pressure of the engine 1 is applied to the pressure chamber 9c of the actuator 9 through the one-way valve 14, and the diaphragm 9b moves the exhaust gas flow path switching valve 8 to the broken line position (closed position in the drawing) via the arm 9a. )
Drive to.

When the engine 1 is warmed up and the determination in step S4 in FIG. 4 is YES, the energization from the control device 10 to the on-off valve 13 is cut off in step S5.
The on-off valve 13 shuts off the connection between the intake negative pressure introducing pipes 15a and 15b. At the same time, since the opening / closing valve 13 communicates its atmosphere opening port with the intake negative pressure introducing pipe 15a, the negative pressure in the pressure chamber 9c of the actuator 9 is rapidly reduced, and the diaphragm 9b is displaced by the force of the spring 9d. , Arm 9
The exhaust gas passage switching valve 8 is driven to the solid line position (valve opening position) in the figure via a.

By the way, in the embodiment of FIG. 7, as described above, the intake negative pressure introducing pipes 15a, 1a to the actuator 9 are provided.
Since the one-way valve 14 is arranged in addition to the on-off valve 13 in the middle of 5b, the one-way valve is opened when the throttle valve 2b of the engine 1 is opened and the intake negative pressure in the intake manifold 2a decreases. The valve 14 is closed to prevent air from flowing into the pressure chamber 9c of the actuator 9 from the intake manifold 2a side.

Therefore, even when the throttle valve 2b of the engine 1 is opened, the negative pressure in the pressure chamber 9c of the actuator 9 is prevented from immediately decreasing by the one-way valve 14, and the large negative pressure of the actuator 9 is maintained. it can. Therefore, when the throttle valve 2b is opened (when the engine intake negative pressure is reduced), the exhaust gas flow path switching valve 8 is affected by exhaust pressure pulsation, vibration of the vehicle body, and the like, and opens from the closed position shown by the broken line. That problem does not occur.

Therefore, it is not necessary to set the actuator 9 to a large size so as to cope with the reduction of the engine intake negative pressure, and the actuator 9 can be downsized.
It is extremely advantageous for mounting on a vehicle. The present invention is not limited to the illustrated embodiments described above, and various modifications are possible.
For example, the recirculation flow paths 6a and 6b are not connected to the exhaust flow path immediately upstream of the catalyst device 4 and the intake manifold 2a of the engine 1 is not connected.
The present invention can be applied to the type of connecting to the side.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the shapes of an expansion tube and a suction tube in the apparatus of the embodiment shown in FIG.

3 (a) to 3 (d) are explanatory views showing the relationship between the spread angle and the flow form of exhaust gas in the expansion tube of FIG.

FIG. 4 is a flow chart showing the operation of the apparatus of one embodiment.

FIG. 5 is a diagram showing how the apparatus according to the embodiment is mounted on a vehicle.

FIG. 6 is an explanatory diagram showing attachment positions of actuators and the like in the apparatus of one embodiment.

FIG. 7 is a configuration diagram of an entire apparatus showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Exhaust manifold, 2a ... Intake manifold, 3 ... Exhaust pipe, 31 ... Expansion pipe, 34 ... Exhaust flow path, 4
... Catalyst device, 5 ... Adsorption device, 6a, 6b ... Reflux flow path, 8
... Exhaust gas flow path switching valve, 9 ... Actuator, 10 ... Control device, 15a, 15b ... Intake negative pressure introducing pipe, 13 ... Open / close valve, 14 ... One-way valve.

Claims (6)

[Claims] 1. A catalyst device provided in an exhaust pipe of an engine, an adsorption device provided in the exhaust pipe downstream of the catalyst device and carrying an adsorbent for adsorbing exhaust gas harmful components, and the catalyst. An exhaust flow path that forms a flow of exhaust gas that does not pass through the adsorption device in the exhaust pipe downstream of the device, and a reflux that recirculates the exhaust gas harmful components adsorbed by the adsorption device to the upstream side of the catalyst device. A flow path, an exhaust gas flow path switching unit that is provided downstream of the adsorption device and is capable of selectively switching the flow of exhaust gas between the flow path of the adsorption device and the exhaust flow path, the adsorption device and the An expansion pipe, which is provided upstream of the exhaust flow passage, is formed so as to have a larger flow passage cross-sectional area than the exhaust pipe, and guides the exhaust gas to the adsorption device or the exhaust flow passage, and the switching means is an engine. Exhaust gas when cold And a control means for switching the exhaust gas to a position that allows the exhaust gas to flow to the exhaust passage when the engine is warmed up. An exhaust gas purifying device, characterized in that the flow of gas is set in a range such that one side wall surface is separated. 2. The spread angle of the expansion tube is 50-80.
The exhaust gas purifying apparatus according to claim 1, wherein the exhaust gas purifying apparatus is set in a range of degrees. 3. The flow path of the adsorption device and the exhaust flow path are arranged adjacent to each other, and the overall cross-sectional shape of the flow path, which is a combination of both flow paths, is formed into an elliptical shape. The exhaust gas purification device according to claim 1 or 2. 4. The flow path of the adsorption device and the exhaust flow path are
The exhaust gas purifying apparatus according to claim 3, wherein the ellipse is arranged adjacent to each other in the major axis direction. 5. The adsorption device and the exhaust passage are arranged below the vehicle body of the vehicle such that the major axis direction of the elliptical shape is substantially horizontal. The exhaust gas purification device according to 3 or 4. 6. An actuator for driving the switching means by engine intake negative pressure, an intake negative pressure introducing passage for introducing engine intake negative pressure to the actuator, and an intake negative pressure introducing passage provided in the intake negative pressure introducing passage. An on-off valve controlled to be opened and closed by means, and a one-way valve provided in the intake negative pressure introduction flow path and allowing the fluid to flow only in one direction from the actuator to the engine intake side. The exhaust gas purification device according to any one of 1 to 5.