JP2023161518A - exhaust system - Google Patents

Abstract

To provide an exhaust system which can suppress power consumed by a plasma reactor.SOLUTION: An exhaust system 14 comprises a catalyst converter 2 connected to an engine 101, an exhaust pipe 3 connected to a downstream side of the catalyst converter 2, a plasma reactor 4 interposed in the middle of the exhaust pipe 3, and a control device 6. The control device 6 makes the plasma reactor 4 discharge electricity when a temperature in the catalyst converter 2 is equal to or higher than a temperature at which a catalyst in the catalyst converter 2 is activated, and an engine 101 is operated in a condition that the generation of particulate substances is assumed, and when the temperature in the catalyst converter 2 is equal to or higher than the temperature at which the catalyst is the catalyst converter 2 is activated, and the engine 101 is operated in a condition that the generation of the particulate substances is not assumed.SELECTED DRAWING: Figure 2

Description

The present invention relates to exhaust systems.

BACKGROUND ART Conventionally, a plasma generation control device has been proposed in which a plasma processing device is provided in the exhaust line of an engine and the plasma processing device is operated at the time of engine startup and acceleration (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 06-335621

Further energy saving is desired in the exhaust line as described in Patent Document 1 mentioned above.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an exhaust system that can suppress the power consumed by a plasma reactor.

The present invention [1] includes a catalytic converter connected to an engine, an exhaust pipe connected downstream of the catalytic converter, a plasma reactor interposed in the middle of the exhaust pipe, and a control device, The control device controls the control device when the temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst in the catalytic converter is activated, and the engine is operating under conditions where particulate matter is expected to be generated. , the temperature in the catalytic converter is higher than the temperature at which the catalyst in the catalytic converter is activated, the engine is operating under conditions where particulate matter is not expected to be generated, and the air-fuel ratio is lean. and an exhaust system for discharging the plasma reactor in some cases.

According to such a configuration, the control device controls whether the engine is operating under conditions where generation of particulate matter is expected, and when the engine is operating under conditions where generation of particulate matter is not expected. , the plasma reactor is discharged when the air-fuel ratio is lean.

By discharging the plasma reactor when the engine is operating under conditions where particulate matter is expected to be generated, particulate matter can be treated while suppressing the power consumed by the plasma reactor.

Further, by discharging the plasma reactor when the air-fuel ratio is lean, particulate matter adsorbed on the electrode panel of the plasma reactor can be decomposed using oxygen in the exhaust gas.

Therefore, oxygen is present in the exhaust gas, and the plasma reactor discharges under conditions favorable for decomposing particulate matter, so that particulate matter adsorbed on the electrode panel can be efficiently decomposed.

As a result, particulate matter adsorbed to the electrode panel can be treated while suppressing the power consumed by the plasma reactor.

In the present invention [2], the control device is configured such that the temperature in the catalytic converter is equal to or higher than the temperature at which the catalyst in the catalytic converter is activated, and the engine is operated under conditions where generation of particulate matter is not expected. and includes the exhaust system of [1] above, which stops the discharge of the plasma reactor when the air-fuel ratio is stoichiometric or rich.

According to such a configuration, power consumption by the plasma reactor can be suppressed by stopping the discharge of the plasma reactor.

Furthermore, if the plasma reactor is discharged when the air-fuel ratio is stoichiometric and the exhaust gas contains oxygen, nitrogen oxides (NOx) may be generated in the exhaust gas.

In this regard, by stopping the discharge of the plasma reactor when the air-fuel ratio is stoichiometric or rich, it is possible to suppress the generation of nitrogen oxides (NOx) when the air-fuel ratio is stoichiometric.

According to the exhaust system of the present invention, electric power consumed by the plasma reactor can be suppressed.

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, a plasma reactor 4, a power supply device 5, a control device 6, a catalyst temperature sensor 7, and an A/F sensor 8.

(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.

(3) Plasma Reactor The plasma reactor 4 is interposed in the middle of the exhaust pipe 3. The plasma reactor 4 decomposes harmful components contained in the exhaust gas. The plasma reactor 4 is a dielectric barrier discharge type plasma reactor.

Specifically, the plasma reactor 4 has a plurality of electrode panels 41. The plurality of electrode panels 41 are arranged at intervals from each other in a direction perpendicular to the direction in which the exhaust pipe 3 extends. Each electrode panel 41 extends in the direction in which the exhaust pipe 3 extends. Each electrode panel 41 has a flat plate shape. Exhaust gas passes between each electrode panel 41.

Each electrode panel 41 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 41, a discharge (dielectric barrier discharge) occurs between each electrode panel 41. As a result, the gas between each electrode panel 41 enters a plasma state. That is, plasma is generated within the plasma reactor 4. Then, harmful components contained in the exhaust gas are decomposed by the plasma. The exhaust gas that has passed through the plasma reactor 4 passes through the exhaust pipe 3 and is discharged outside the vehicle.

(4) Power Supply Device The power supply device 5 can supply electric power from the battery 102 to each electrode panel 41 of the plasma reactor 4. Power supply device 5 is electrically connected to battery 102 . Further, the power supply device 5 is electrically connected to each electrode panel 41. The power supply device 5 can be switched between an on state and an off state. When the power supply device 5 is in the on state, the power supply device 5 can supply power to the electrode panel 41. Further, when the power supply device 5 is in the off state, the power supply device 5 does not supply power to the electrode panel 41.

(5) Control device The control device 6 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 Unit). Memory) etc. Equipped with Control device 6 is electrically connected to battery 102 . The control device 6 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 6 is electrically connected to power supply device 5 . The control device 6 switches the power supply device 5 to an on state or an off state by sending a predetermined electric signal to the power supply device 5. That is, the control device 6 controls the power supply device 5. In other words, the control device 6 controls the plasma reactor 4 via the power supply device 5.

Further, the control device 6 is electrically connected to an accelerator pedal (not shown). The control device 6 can receive an electrical signal (accelerator instruction value) according to the position of the accelerator pedal. Further, the control device 6 is electrically connected to a sensor (not shown) that measures the temperature of the cooling water of the engine 101. Further, the control device 6 is electrically connected to a catalyst temperature sensor 7 and an A/F sensor 8.

(6) Sensor The catalyst temperature sensor 7 is attached to the catalytic converter 2. Catalyst temperature sensor 7 measures temperature T _(S/C) inside catalytic converter 2.

A/F sensor 8 is installed between engine 101 and catalytic converter 2. A/F sensor 8 measures the oxygen concentration in exhaust gas.

2. Control of Exhaust System Next, control of the exhaust system 1 will be described with reference to FIG. 2.

When the ignition switch of vehicle 100 is turned on, control device 6 is activated. Furthermore, when the starter motor rotates, the engine 101 is started (S1). 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 (particulate matter and hydrocarbons) in the exhaust gas flow into the exhaust pipe 3 without being decomposed by the catalytic converter 2.

Therefore, when the engine 101 starts, the control device 6 switches the power supply device 5 from the off state to the on state (plasma reactor 4: on state) (S2).

Then, particulate matter and hydrocarbons in the exhaust gas are decomposed by the plasma reactor 4.

The control device 6 maintains the plasma reactor 4 in the ON state when the temperature T _(S/C) inside the catalytic converter 2 is lower than the catalyst activation temperature T1 (S3: NO).

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

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

Therefore, when the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the catalyst activation temperature T1, the exhaust gas that has passed through the catalytic converter 2 contains almost no particulate matter and hydrocarbons.

Therefore, the control device 6 causes the plasma reactor 4 to discharge when the particulate matter needs to be treated, and stops the plasma reactor 4 from discharging when the particulate matter does not need to be treated.

Specifically, when the temperature T _(S/C) inside the catalytic converter 2 becomes equal to or higher than the catalyst activation temperature T1 (S3: YES), the control device 6 controls the engine 101 under conditions where particulate matter is expected to be generated. It is determined whether or not it is operating (S4).

Specifically, whether or not the engine 101 is operating under conditions where the generation of particulate matter is expected is determined by the temperature of the cooling water of the engine 101, the accelerator instruction value from the accelerator pedal (not shown), the A/F sensor 8 It is determined from the air-fuel ratio based on.

Note that in the following description, "air-fuel ratio" is the air-fuel ratio when the fuel is gasoline. The case where the air-fuel ratio is rich means that the air-fuel ratio is less than the stoichiometric air-fuel ratio (14.7). When the air-fuel ratio is lean, it means that the air-fuel ratio exceeds the stoichiometric air-fuel ratio. The case where the air-fuel ratio is stoichiometric means that the air-fuel ratio is close to the stoichiometric air-fuel ratio.

Specifically, when the temperature of the cooling water of the engine 101 is lower than a predetermined temperature, the accelerator instruction value is higher than the predetermined value, and the air-fuel ratio is rich, the control device 6 controls the engine 101 to generate particulate matter. is operating under the expected conditions (S4: YES)
In this case, since the particulate matter needs to be treated, the control device 6 turns on the plasma reactor 4 (S5).

In other words, when the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the catalyst activation temperature T1 (S3: YES), and the engine 101 is operating under conditions where particulate matter is expected to be generated. (S4: YES), the control device 6 causes the plasma reactor 4 to discharge (S5).

On the other hand, if the engine 101 is not operating under conditions where particulate matter is expected to be generated (S4: NO) and the air-fuel ratio is stoichiometric or rich (S6: NO), particulate matter Since no processing is necessary, the control device 6 turns off the plasma reactor 4 (S7).

In other words, the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the catalytic activation temperature T1 (S3: YES), and the engine 101 is operating under conditions where generation of particulate matter is not expected (S4: NO). ), if the air-fuel ratio is stoichiometric or rich (S6: NO), the control device 6 stops the discharge of the plasma reactor 4 (S7).

Thereby, power consumption by the plasma reactor 4 can be suppressed, and energy saving can be achieved.

Further, if the plasma reactor 4 is discharged when the air-fuel ratio is not rich and the exhaust gas contains oxygen, nitrogen oxides (NOx) may be generated in the exhaust gas. In this regard, by stopping the discharge of the plasma reactor 4 when the air-fuel ratio is stoichiometric or rich, it is possible to suppress the generation of nitrogen oxides (NOx) when the air-fuel ratio is stoichiometric.

After stopping the discharge of the plasma reactor 4, the control device 6 determines again whether the engine 101 is operating under conditions where generation of particulate matter is expected (S4).

Note that when the engine 101 is not operating under conditions where generation of particulate matter is expected (S4: NO) and the air-fuel ratio is lean (S6: YES), the control device 6 controls the plasma reactor. 4 is turned on (S8).

In other words, the temperature T _(S/C) inside the catalytic converter 2 is equal to or higher than the catalytic activation temperature T1 (S3: YES), and the engine 101 is operating under conditions where generation of particulate matter is not expected (S4: NO). ) and the air-fuel ratio is lean (S6: NO), the control device 6 causes the plasma reactor 4 to discharge (S8).

When the air-fuel ratio is lean, the oxygen concentration in the exhaust gas is high. Therefore, by discharging the plasma reactor 4 when the air-fuel ratio is lean, the particulate matter adsorbed on the electrode panel 41 of the plasma reactor 4 can be decomposed using oxygen in the exhaust gas.

Then, when the engine 101 stops (S9: YES), the control device 6 turns off the plasma reactor 4 (S10).

Note that if the engine 101 does not stop (S9: NO), the control device 6 monitors the temperature T _(S/C) inside the catalytic converter 2 again (S3). That is, the control device 6 continues to control the plasma reactor 4 until the engine 101 stops (S9: NO).

3. Effects (1) According to the exhaust system 1, as shown in FIG. 2, the control device 6 controls whether the engine 101 is operating under conditions where particulate matter is expected to be generated (S4: YES), When the engine 101 is operating under conditions where generation of particulate matter is not expected (S4: NO) and the air-fuel ratio is lean (S6: YES), the plasma reactor 4 is caused to discharge.

Therefore, by discharging the plasma reactor 4 when the engine 101 is operating under conditions where particulate matter is expected to be generated, particulate matter can be treated while suppressing the power consumed by the plasma reactor 4. .

Further, by discharging the plasma reactor 4 when the air-fuel ratio is lean, particulate matter adsorbed on the electrode panel 41 of the plasma reactor 4 can be decomposed using oxygen in the exhaust gas.

Therefore, oxygen is present in the exhaust gas, and the plasma reactor 4 discharges under conditions favorable for decomposing particulate matter, so that the particulate matter adsorbed on the electrode panel 41 can be efficiently decomposed.

As a result, particulate matter adsorbed to the electrode panel 41 can be treated while suppressing the power consumed by the plasma reactor 4.

(2) According to the exhaust system 1, as shown in FIG. 2, power consumption by the plasma reactor 4 can be suppressed by stopping the discharge of the plasma reactor 4.

Furthermore, if the plasma reactor 4 is discharged when the air-fuel ratio is stoichiometric and the exhaust gas contains oxygen, nitrogen oxides (NOx) may be generated in the exhaust gas.

In this regard, by stopping the discharge of the plasma reactor 4 when the air-fuel ratio is stoichiometric or rich, it is possible to suppress the generation of nitrogen oxides (NOx) when the air-fuel ratio is stoichiometric.

1 Exhaust system 2 Catalytic converter 3 Exhaust pipe 4 Plasma reactor 6 Control device

Claims (2)

a catalytic converter connected to the engine;
an exhaust pipe connected to the downstream side of the catalytic converter;
a plasma reactor interposed in the middle of the exhaust pipe;
and a control device;
The control device includes:
the temperature within the catalytic converter is equal to or higher than the temperature at which the catalyst within the catalytic converter is activated, and the engine is operating under conditions where particulate matter is expected to be generated;
The temperature within the catalytic converter is equal to or higher than the temperature at which the catalyst within the catalytic converter is activated, the engine is operating under conditions where generation of particulate matter is not expected, and the air-fuel ratio is lean. and an exhaust system for discharging said plasma reactor. The control device includes:
the temperature within the catalytic converter is equal to or higher than the temperature at which the catalyst within the catalytic converter is activated, the engine is operating under conditions where no particulate matter is expected to be generated, and the air-fuel ratio is stoichiometric or rich. 2. The exhaust system according to claim 1, wherein the discharge system of the plasma reactor is stopped when the plasma reactor is.

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