JP2023136355A - exhaust system - Google Patents

Abstract

To provide an exhaust system capable of suppressing discharge of hydrocarbon immediately after start of an engine.SOLUTION: An exhaust system 1 includes: a catalytic converter 2 connected to an engine 101; an exhaust pipe 3 connected to a downstream side of the catalytic converter 2, the exhaust pipe 3 branched into a first exhaust pipe 31 and a second exhaust pipe 32 in the middle; a plasma reactor 5 interposed in the middle of the first exhaust pipe 3; an adsorption member 4 interposed in the middle of the first exhaust pipe 31, disposed between the catalytic converter 2 and the plasma reactor 5 and capable of adsorbing hydrocarbon in exhaust gas; and a valve 6 for adjusting balance between the amount of exhaust gas passing through the first exhaust pipe 31 and the amount of exhaust gas passing through the second exhaust pipe 32.SELECTED DRAWING: Figure 1

Description

The present invention relates to exhaust systems.

BACKGROUND ART Conventionally, an exhaust gas purification device including a plasma reactor is known as a device for decomposing harmful components such as hydrocarbons (HC) contained in exhaust gas (for example, see Patent Document 1).

This exhaust gas purification device includes a bypass flow path that bypasses the main flow path upstream of the exhaust purification catalyst, and a plasma reactor containing a built-in HC adsorption catalyst is disposed in the bypass flow path.

In this exhaust purification device, when the activity of the exhaust purification catalyst is not sufficient, the exhaust gas is caused to flow through the bypass flow path, hydrocarbons are adsorbed by the HC adsorption catalyst, and the plasma reactor assists in the purification of the hydrocarbons. ing.

Japanese Patent Application Publication No. 2005-90400

However, in the exhaust purification device as described in Patent Document 1, when the exhaust gas is passed through the bypass flow path, the HC adsorption catalyst is disposed upstream of the exhaust purification catalyst, so the temperature of the exhaust purification catalyst increases. In a low state, the temperature of the HC adsorption catalyst may rise.

Therefore, when the activity of the exhaust purification catalyst is not sufficient, the temperature of the HC adsorption catalyst may rise, and the hydrocarbons adsorbed on the HC adsorption catalyst may be desorbed.

In that case, hydrocarbons in the exhaust gas and hydrocarbons desorbed from the HC adsorption catalyst are treated only in the plasma reactor, making it difficult to suppress the discharge of hydrocarbons.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an exhaust system that can suppress hydrocarbon emissions immediately after starting an engine.

The present invention [1] includes a catalytic converter connected to an engine, and an exhaust pipe connected downstream of the catalytic converter, which branches into a first exhaust pipe and a second exhaust pipe midway. , a plasma reactor interposed in the middle of the first exhaust pipe; and a plasma reactor interposed in the middle of the first exhaust pipe, and arranged between the catalytic converter and the plasma reactor, for removing hydrocarbons in exhaust gas. The exhaust system includes an adsorption member capable of adsorption, and a valve for adjusting the balance between the amount of exhaust gas passing through the first exhaust pipe and the amount of exhaust gas passing through the second exhaust pipe. .

According to this configuration, until the catalyst in the catalytic converter is activated, the exhaust gas that has passed through the catalytic converter is passed through the first exhaust pipe, and the hydrocarbons in the exhaust gas are removed by the adsorption member and the plasma reactor. can be processed.

At this time, exhaust gas from the engine passes through the catalytic converter, the adsorption member, and the plasma reactor in this order.

Therefore, the temperature of the catalytic converter can be raised faster than that of the adsorption member. As a result, the catalyst in the catalytic converter can be activated before the hydrocarbons adsorbed on the adsorption member are desorbed from the adsorption member.

After the catalyst in the catalytic converter is activated, the hydrocarbons in the exhaust gas can be treated by the catalytic converter, while the hydrocarbons desorbed from the adsorption member can be treated by the plasma reactor.

As a result, the amount of hydrocarbon emissions immediately after the engine starts can be suppressed.

The present invention [2] further includes a control device, and when the temperature in the catalytic converter is lower than a first temperature that is a temperature at which a catalyst in the catalytic converter is activated, the control device controls the exhaust gas. The exhaust system according to [1] above, wherein the valve is controlled so that all the exhaust gas passes through the first exhaust pipe.

According to such a configuration, hydrocarbons can be processed by the adsorption member and the plasma reactor until the catalyst in the catalytic converter is activated.

Therefore, hydrocarbon emissions can be suppressed until the catalyst in the catalytic converter is activated.

The present invention [3] is characterized in that the control device is configured to control a second temperature in which the temperature inside the catalytic converter is equal to or higher than the first temperature, and the temperature of the adsorption member is a temperature at which hydrocarbons are desorbed from the adsorption member. If the exhaust gas is less than the predetermined amount, the exhaust system includes the exhaust system of [2] above, which controls the valve so that the amount of exhaust gas passing through the first exhaust pipe is equal to or less than a predetermined amount.

According to such a configuration, when the temperature inside the catalytic converter becomes equal to or higher than the first temperature, hydrocarbons in the exhaust gas can be decomposed by the activated catalyst within the catalytic converter.

Therefore, by controlling the valve, a predetermined amount or less of the exhaust gas that has passed through the catalytic converter is allowed to flow into the first exhaust pipe, and an amount exceeding the predetermined amount is allowed to flow into the second exhaust pipe.

Thereby, exhaust gas can be efficiently discharged to the outside of the vehicle using the second exhaust pipe while increasing the temperature of the adsorption member.

According to the exhaust system of the present invention, it is possible to suppress the amount of hydrocarbon emissions immediately after engine startup.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with an embodiment of the exhaust system of the present invention. FIG. 2 is a flowchart for explaining control of the exhaust system shown in FIG.

1. Configuration of Exhaust System As shown in FIG. 1, the exhaust system 1 is mounted on, for example, a vehicle 100.

Vehicle 100 includes an engine 101, an electrical system including a battery 102, an intake system (not shown) for intake air into the engine 101, a fuel injection system (not shown) for supplying fuel to the engine 101, and exhaust air from the engine 101. An exhaust system 1 is provided.

The exhaust system 1 includes a catalytic converter 2, an exhaust pipe 3, an adsorption member 4, a plasma reactor 5, a valve 6, a power supply device 7, a control device 8, a first temperature sensor 9, and a second temperature sensor. 10 and an air flow meter 11.

(1) Catalytic Converter The catalytic converter 2 is connected to the engine 101. Specifically, the catalytic converter 2 is a three-way catalytic converter that has a three-way catalyst therein as an example of a catalyst. The catalytic converter 2 uses an internal catalyst to decompose harmful components (hydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO)) contained in exhaust gas.

(2) Exhaust pipe The exhaust pipe 3 is connected to the catalytic converter 2. The exhaust pipe 3 is connected to the downstream side of the catalytic converter 2 in the direction in which exhaust gas flows. Exhaust gas discharged from the engine 101 and passed through the catalytic converter 2 passes through the exhaust pipe 3 and is discharged outside the vehicle. The exhaust pipe 3 branches into a first exhaust pipe 31 and a second exhaust pipe 32 in the middle. In other words, the exhaust pipe 3 includes a first exhaust pipe 31 and a second exhaust pipe 32.

The first exhaust pipe 31 is a pipe for guiding exhaust gas to the adsorption member 4 and the plasma reactor 5. An adsorption member 4 and a plasma reactor 5 are interposed in the middle of the first exhaust pipe 31 .

The second exhaust pipe 32 is a pipe for bypassing the adsorption member 4 and the plasma reactor 5 and discharging exhaust gas. The second exhaust pipe 32 has an upstream end 32A and a downstream end 32B in the direction in which exhaust gas flows. The upstream end 32A is connected to the first exhaust pipe 31 between the adsorption member 4 and the catalytic converter 2. The downstream end 32B is connected to the first exhaust pipe 31 on the opposite side of the catalytic converter 2 with respect to the plasma reactor 5. The pressure loss when the exhaust gas passes through the second exhaust pipe 32 is smaller than the pressure loss when the exhaust gas passes through the first exhaust pipe 31. Preferably, there is no intervening member in the middle of the second exhaust pipe 32. The second exhaust pipe 32 is preferably arranged below the first exhaust pipe 31. By arranging the second exhaust pipe 32 below the first exhaust pipe 31, the adsorption member 4 and plasma reactor 5 in the first exhaust pipe 31 can be protected from water etc. discharged from the engine 101. .

(3) Adsorption member The adsorption member 4 is interposed in the middle of the first exhaust pipe 31. The adsorption member 4 is arranged downstream of the catalytic converter 2 in the direction in which exhaust gas flows. Adsorption member 4 is arranged between catalytic converter 2 and plasma reactor 5 in the direction in which exhaust gas flows. The adsorption member 4 is capable of adsorbing hydrocarbons in exhaust gas.

Specifically, the adsorption member 4 has a cylindrical shape. The adsorption member 4 extends in the direction in which the first exhaust pipe 31 extends. The adsorption member 4 has a carrier and an adsorption layer inside. The carrier extends in the direction in which the adsorption member 4 extends. The carrier supports the adsorption layer. The carrier is mesh-like or honeycomb-like and has a plurality of holes through which exhaust gas passes. The adsorption layer covers the inner surface of the pores of the carrier. The adsorption layer is made of, for example, zeolite. When the exhaust gas passes through the pores of the carrier, the adsorption layer adsorbs hydrocarbons in the exhaust gas.

(4) Plasma Reactor The plasma reactor 5 is interposed in the middle of the first exhaust pipe 31. The plasma reactor 5 is arranged downstream of the adsorption member 4 in the direction in which exhaust gas flows. The plasma reactor 5 decomposes harmful components contained in the exhaust gas that has passed through the adsorption member 4. The plasma reactor 5 is a dielectric barrier discharge type plasma reactor.

Specifically, the plasma reactor 5 has a plurality of electrode panels 51. The plurality of electrode panels 51 are arranged at intervals from each other in a direction perpendicular to the direction in which the first exhaust pipe 31 extends. Each electrode panel 51 extends in the direction in which the first exhaust pipe 31 extends. Each electrode panel 51 has a flat plate shape. Exhaust gas passes between each electrode panel 51.

Each electrode panel 51 has a conductor layer and a dielectric layer covering the conductor layer. The conductor layer is made of a metal (conductor) such as tungsten, for example. The dielectric layer is made of ceramic (dielectric) such as aluminum oxide, for example.

When power is supplied to each electrode panel 51, a discharge (dielectric barrier discharge) occurs between each electrode panel 51. As a result, the gas between each electrode panel 51 enters a plasma state. That is, plasma is generated within the plasma reactor 5. Then, harmful components contained in the exhaust gas are decomposed by the plasma. The exhaust gas that has passed through the plasma reactor 5 passes through the exhaust pipe 3 and is discharged outside the vehicle.

(5) Valve The valve 6 adjusts the balance between the amount of exhaust gas passing through the first exhaust pipe 31 and the amount of exhaust gas passing through the second exhaust pipe 32. The valve 6 is arranged at a connection portion between the downstream end 32B of the second exhaust pipe 32 and the first exhaust pipe 31. Note that the position of the valve 6 is not limited. For example, the valve 6 may be arranged at a connection portion between the upstream end 32A of the second exhaust pipe 32 and the first exhaust pipe 31. Further, the valve 6 may be provided in the first exhaust pipe 31 and the second exhaust pipe 32, respectively. Valve 6 is an electromagnetic valve.

In the following description, when referring to the opening degree of the valve 6, the opening degree on the first exhaust pipe 31 side is used as a reference. For example, when the opening degree of the valve 6 is 100%, all of the exhaust gas passes through the first exhaust pipe 31. When the opening degree of the valve 6 is 100%, the exhaust gas does not pass through the second exhaust pipe 32. When the opening degree of the valve 6 is 0%, all of the exhaust gas passes through the second exhaust pipe 32. When the opening degree of the valve 6 is 0%, the exhaust gas does not pass through the first exhaust pipe 31.

(4) Power supply device The power supply device 7 can supply electric power from the battery 102 to each electrode panel 51 of the plasma reactor 5. Power supply device 7 is electrically connected to battery 102 . Further, the power supply device 7 is electrically connected to each electrode panel 51. The power supply device 7 can be switched between an on state and an off state. When the power supply device 7 is in the on state, the power supply device 7 can supply power to the electrode panel 51. Further, when the power supply device 7 is in the off state, the power supply device 7 does not supply power to the electrode panel 51.

(5) Control device The control device 8 is an ECU (Electronic Control Unit) that executes electrical control in the vehicle 100, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) etc. Equipped with Control device 8 is electrically connected to battery 102 . The control device 8 is activated by being supplied with electric power from the battery 102 when the ignition switch of the vehicle 100 is turned on.

Control device 8 is electrically connected to power supply device 7 . The control device 8 switches the power supply device 7 to an on state or an off state by sending a predetermined electric signal to the power supply device 7. That is, the control device 8 controls the power supply device 7. In other words, the control device 8 controls the plasma reactor 5 via the power supply device 7.

Further, the control device 8 is electrically connected to the valve 6 . The control device 8 controls the opening degree of the valve 6.

Further, the control device 8 is electrically connected to an accelerator pedal (not shown). The control device 8 can receive an electrical signal (accelerator instruction value) according to the position of the accelerator pedal. Further, the control device 8 is electrically connected to a first temperature sensor 9, a second temperature sensor 10, and an air flow meter 11.

(6) Sensor The first temperature sensor 9 is attached to the catalytic converter 2. The first temperature sensor 9 measures the temperature T _(S/C) inside the catalytic converter 2.

The second temperature sensor 10 is attached to the first exhaust pipe 31. The second temperature sensor 10 measures the temperature T _(U/F) of the adsorption member 4.

Air flow meter 11 is attached to first exhaust pipe 31 . The air flow meter 11 measures the flow rate of exhaust gas passing through the first exhaust pipe 31.

2. Control of Exhaust System Next, control of the exhaust system 1 will be explained.

When the ignition switch of vehicle 100 is turned on, control device 8 is activated. Furthermore, when the starter motor rotates, the engine 101 is started. When engine 101 starts, exhaust gas from engine 101 flows into catalytic converter 2 .

However, immediately after the engine 101 is started, the catalyst in the catalytic converter 2 is not activated and has a low ability to decompose harmful components. Therefore, harmful components in the exhaust gas flow into the exhaust pipe 3 without being decomposed by the catalytic converter 2.

Immediately after engine 101 is started, the proportion of hydrocarbons in the exhaust gas that has passed through catalytic converter 2 is, for example, 1% by volume or more.

(1) Valve control immediately after engine starting As shown in FIG. 2, when the engine 101 starts, the control device 8 switches the power supply device 7 from the off state to the on state (plasma reactor 5: on state), and the valve 6 Set the opening degree to 100% (S1).

Then, all of the exhaust gas passes through the first exhaust pipe 31. Hydrocarbons in the exhaust gas are adsorbed by the adsorption member 4 . Furthermore, hydrocarbons in the exhaust gas that has passed through the adsorption member 4 are decomposed by the plasma reactor 5. Therefore, the discharge of hydrocarbons can be suppressed even when the catalyst in the catalytic converter 2 is not activated.

The proportion of hydrocarbons in the exhaust gas that has passed through the adsorption member 4 and the plasma reactor 5 is, for example, 0.5% by volume or less. Even immediately after starting the engine when the catalytic converter 2 is not activated, the proportion of hydrocarbons in the exhaust gas can be halved by the adsorption member 4 and the plasma reactor 5.

Next, when the temperature T _(S/C) inside the catalytic converter 2 is less than the first temperature T1 (S2: NO), the control device 8 maintains the opening degree of the valve 6 at 100% (S1). That is, when the temperature T _(S/C) inside the catalytic converter 2 is lower than the first temperature T1 (S2: NO), the control device 8 controls the controller 8 so that all of the exhaust gas passes through the first exhaust pipe 31. Control valve 6.

The first temperature T1 is a temperature at which the catalyst in the catalytic converter 2 is activated. The first temperature T1 is, for example, 300°C.

By causing all of the exhaust gas to flow into the first exhaust pipe 31 when the temperature T _(S/C) inside the catalytic converter 2 is less than the first temperature T1, until the catalyst inside the catalytic converter 2 is activated, Hydrocarbons can be treated by the adsorption member 4 and the plasma reactor 5. Thereby, the discharge of hydrocarbons can be suppressed until the catalyst in the catalytic converter 2 is activated.

(2) First valve control Next, the control device 8 executes the first valve control when the temperature T _(S/C) inside the catalytic converter 2 becomes equal to or higher than the first temperature T1 (S2: YES). (S3).

In the first valve control (S3), the control device 8 controls the valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is equal to or less than the first predetermined amount. In other words, in the first valve control (S3), the control device 8 adjusts the opening degree of the valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is equal to or less than the first predetermined amount. Note that the portion of the exhaust gas that exceeds the first predetermined amount flows into the second exhaust pipe 32.

The first predetermined amount is, for example, 5 g/sec.

When the temperature T _(U/F) of the adsorption member 4 is less than the second temperature T2 (S4: NO), the control device 8 continues the first valve control (S3). In other words, the control device 8 determines that the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the first temperature T1 (S2: YES), and the temperature T _(U/F) of the adsorption member 4 is lower than the second temperature T2. If so (S4: NO), the valve 6 is controlled so that the amount of exhaust gas passing through the first exhaust pipe 31 is equal to or less than the first predetermined amount (S3).

The second temperature is the temperature at which hydrocarbons are desorbed from the adsorption member 4. The second temperature T2 is, for example, 300°C.

When the temperature T _(S/C) inside the catalytic converter 2 becomes equal to or higher than the first temperature T1, the catalyst inside the catalytic converter 2 is activated. Therefore, the catalyst in the catalytic converter 2 can decompose hydrocarbons in the exhaust gas.

Therefore, when the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the first temperature T1, the exhaust gas that has passed through the catalytic converter 2 contains almost no hydrocarbons. When the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the first temperature T1, the proportion of hydrocarbons in the exhaust gas that has passed through the catalytic converter 2 is, for example, 0.01% by volume or less.

Therefore, in the first valve control (S3), the opening degree of the valve 6 is adjusted so that a first predetermined amount or less of the exhaust gas that has passed through the catalytic converter 2 flows into the first exhaust pipe 31, and the first predetermined amount The amount exceeding this amount flows into the second exhaust pipe 32.

Thereby, while increasing the temperature of the adsorption member 4, exhaust gas can be efficiently discharged to the outside of the vehicle by using the second exhaust pipe 32, which has a lower pressure loss than the first exhaust pipe 31.

(3) Second valve control Next, when the temperature T _(U/F) of the adsorption member 4 becomes equal to or higher than the second temperature T2 (S4: YES), the control device 8 executes the second valve control ( S5).

When the temperature T _(U/F) of the adsorption member 4 is equal to or higher than the second temperature T2, the hydrocarbons adsorbed by the adsorption member 4 are desorbed from the adsorption member 4. The hydrocarbons desorbed from the adsorption member 4 are decomposed by the plasma reactor 5.

In the second valve control (S5), the control device 8 controls the valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is equal to or less than the second predetermined amount. In other words, in the second valve control (S5), the control device 8 adjusts the opening degree of the valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is equal to or less than the second predetermined amount. Note that the portion of the exhaust gas that exceeds the second predetermined amount flows into the second exhaust pipe 32.

The second predetermined amount is greater than the first predetermined amount. The second predetermined amount is set within a range in which the hydrocarbons desorbed from the adsorption member 4 can be decomposed by the plasma reactor 5. The second predetermined amount is, for example, 20 g/sec.

By increasing the amount of exhaust gas flowing into the first exhaust pipe 31 while the temperature T _(U/F) of the adsorption member 4 is higher than the second temperature T2, the hydrocarbons adsorbed by the adsorption member 4 are can be efficiently desorbed.

The control device 8 continues the second valve control (S5) until a predetermined time has elapsed since the start of the second valve control (S6: NO).

The predetermined time is set so that almost all of the hydrocarbons adsorbed by the adsorption member 4 can be desorbed. The predetermined time is, for example, 10 minutes.

(4) Termination of valve control If a predetermined time has elapsed since starting the second valve control (S6: YES), the control device 8 sets the valve opening to 0% (S7) and terminates the valve control. . Further, the control device 8 switches the power supply device 7 from the on state to the off state (plasma reactor 5: off state).

When the valve control is completed, all of the exhaust gas that has passed through the catalytic converter 2 passes through the second exhaust pipe 32 and is discharged to the outside of the vehicle.

3. Effects (1) As shown in FIG. 1, according to the exhaust system 1, the exhaust gas that has passed through the catalytic converter 2 is passed through the first exhaust pipe 31 until the catalyst in the catalytic converter 2 is activated. , the adsorption member 4 and the plasma reactor 5 can treat hydrocarbons in the exhaust gas.

At this time, exhaust gas from the engine 101 passes through the catalytic converter 2, the adsorption member 4, and the plasma reactor 5 in this order.

Therefore, the temperature of the catalytic converter 2 can be raised faster than that of the adsorption member 4. As a result, the catalyst in the catalytic converter 2 can be activated before the hydrocarbons adsorbed on the adsorption member 4 are desorbed from the adsorption member 4.

After the catalyst in the catalytic converter 2 is activated, the hydrocarbons in the exhaust gas can be treated in the catalytic converter 2 while the hydrocarbons desorbed from the adsorption member 4 can be treated in the plasma reactor 5.

As a result, the amount of hydrocarbon emissions immediately after the engine starts can be suppressed.

(2) As shown in FIG. 2, according to the exhaust system 1, when the temperature T _(S/C) inside the catalytic converter 2 is less than the first temperature T1 (S2: NO), the control device 8 controls the exhaust The valve 6 is controlled so that all of the gas passes through the first exhaust pipe 31. The first temperature T1 is a temperature at which the catalyst in the catalytic converter 2 is activated.

Thereby, hydrocarbons can be processed by the adsorption member 4 and the plasma reactor 5 until the catalyst in the catalytic converter 2 is activated.

As a result, hydrocarbon emissions can be suppressed until the catalyst in the catalytic converter 2 is activated.

(3) As shown in FIG. 2, according to the exhaust system 1, the control device 8 determines that the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the first temperature T1 (S2: YES), and the adsorption member 4 is lower than the second temperature T2 (S4: _NO ), the valve 6 is turned on so that the amount of exhaust gas passing through the first exhaust pipe 31 is equal to or less than the first predetermined amount. control (S3). The second temperature T2 is a temperature at which hydrocarbons are desorbed from the adsorption member 4.

When the temperature T _(S/C) inside the catalytic converter 2 becomes equal to or higher than the first temperature T1, the catalyst inside the catalytic converter 2 is activated. Therefore, the catalyst in the catalytic converter 2 can decompose hydrocarbons in the exhaust gas.

Therefore, by controlling the valve 6, the first predetermined amount or less of the exhaust gas that has passed through the catalytic converter 2 flows into the first exhaust pipe 31, and the amount exceeding the first predetermined amount flows into the second exhaust pipe 32. Flow.

Thereby, while increasing the temperature of the adsorption member 4, exhaust gas can be efficiently discharged to the outside of the vehicle by using the second exhaust pipe 32, which has a lower pressure loss than the first exhaust pipe 31.

4. Modifications (1) In determining whether to start the first valve control (S3) (S2), the control device 8 may use the integrated value of the flow rate of exhaust gas and the air-fuel ratio.

(2) In the first valve control (S3), the opening degree of the valve 6 may be controlled based on the amount of exhaust gas discharged from the engine 101. The amount of exhaust gas discharged from the engine 101 may be calculated from the amount of intake air, for example. In this case, if the amount of exhaust gas discharged from the engine 101 is less than or equal to the first predetermined amount, the valve opening degree is controlled to 100%, and the amount of exhaust gas discharged from the engine 101 exceeds the first predetermined amount. In this case, the valve opening degree may be controlled to 0%.

(3) In determining whether to start the second valve control (S5) (S4), the control device 8 may use the integrated value of the flow rate of exhaust gas and the air-fuel ratio.

(4) In determining whether to end the valve control (S6), the control device 8 may use the temperature of the adsorption member 4 and the operating conditions of the engine 101.

1 Exhaust system 2 Catalytic converter 3 Exhaust pipe 4 Adsorption member 5 Plasma reactor 6 Valve 8 Control device 31 First exhaust pipe 32 Second exhaust pipe 101 Engine

Claims (3)

a catalytic converter connected to the engine;
an exhaust pipe connected to the downstream side of the catalytic converter, the exhaust pipe branching into a first exhaust pipe and a second exhaust pipe halfway;
a plasma reactor interposed in the middle of the first exhaust pipe;
an adsorption member that is interposed in the middle of the first exhaust pipe and arranged between the catalytic converter and the plasma reactor, and is capable of adsorbing hydrocarbons in exhaust gas;
An exhaust system comprising: a valve for adjusting the balance between the amount of exhaust gas passing through the first exhaust pipe and the amount of exhaust gas passing through the second exhaust pipe. further comprising a control device;
The control device includes:
controlling the valve so that all of the exhaust gas passes through the first exhaust pipe when the temperature within the catalytic converter is below a first temperature at which a catalyst within the catalytic converter is activated; , an exhaust system according to claim 1. The control device includes:
When the temperature inside the catalytic converter is equal to or higher than the first temperature and the temperature of the adsorption member is less than a second temperature, which is a temperature at which hydrocarbons are desorbed from the adsorption member, hydrocarbons pass through the first exhaust pipe. 3. The exhaust system according to claim 2, wherein the valve is controlled so that the amount of exhaust gas generated is equal to or less than a predetermined amount.

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