exhaust system

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

[Technical Field]

[0001] The present invention relates to exhaust systems. [Background technology]

[0002] BACKGROUND ART Conventionally, a plasma generation control device has been proposed in which a plasma processing device is provided in an exhaust line of an engine and the plasma processing device is activated when the engine is started and accelerated (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 06-335621 Summary of the Invention [Problem to be solved by the invention]

[0004] In the exhaust line described in the above-mentioned Patent Document 1, further energy saving is desired.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an exhaust system that can reduce the power consumed by a plasma reactor. [Means for solving the problem]

[0006] The present invention [1] includes an exhaust system comprising a catalytic converter connected to an engine, an exhaust pipe connected downstream of the catalytic converter, a plasma reactor interposed in the exhaust pipe, and a control device, wherein the control device causes the plasma reactor to discharge when the temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst inside the catalytic converter is activated and the engine is operating under conditions where particulate matter is expected to be generated, and when the temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst inside 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.

[0007] With this configuration, the control device causes the plasma reactor to discharge when the engine is operating under conditions in which the generation of particulate matter is expected, and when the engine is operating under conditions in which the generation of particulate matter is not expected and the air-fuel ratio is lean.

[0008] By discharging the plasma reactor when the engine is operating under conditions that are likely to generate particulate matter, the particulate matter can be treated while reducing the power consumed by the plasma reactor.

[0009] Furthermore, when the air-fuel ratio is lean, the plasma reactor discharges, and oxygen in the exhaust gas is used to decompose the particulate matter adsorbed on the electrode panels of the plasma reactor.

[0010] Therefore, oxygen is present in the exhaust gas, and the plasma reactor discharges under conditions favorable for decomposing particulate matter, thereby enabling the particulate matter adsorbed on the electrode panel to be efficiently decomposed.

[0011] As a result, the particulate matter adsorbed on the electrode panel can be treated while suppressing the power consumed by the plasma reactor.

[0012] The present invention [2] includes the exhaust system of the above [1], wherein the control device stops the discharge of the plasma reactor when the temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst inside the catalytic converter is activated, the engine is operating under conditions where the generation of particulate matter is not expected, and the air-fuel ratio is stoichiometric or rich.

[0013] According to this configuration, by stopping the discharge of the plasma reactor, it is possible to suppress the power consumption by the plasma reactor.

[0014] Furthermore, when the air-fuel ratio is stoichiometric and oxygen is contained in the exhaust gas, if a plasma reactor is discharged, nitrogen oxides (NOx) may be generated in the exhaust gas.

[0015] 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. [Effects of the Invention]

[0016] The exhaust system of the present invention can reduce the power consumed by the plasma reactor. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with an embodiment of an exhaust system of the present invention. [Figure 2] FIG. 2 is a flowchart for explaining the control of the exhaust system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. Exhaust system configuration As shown in FIG. 1, the exhaust system 1 is mounted on a vehicle 100, for example.

[0019] The vehicle 100 includes an engine 101, an electrical system including a battery 102, an intake system (not shown) for drawing air into the engine 101, a fuel injection system (not shown) for supplying fuel to the engine 101, and an exhaust system 1 for exhausting air from the engine 101.

[0020] The exhaust system 1 includes a catalytic converter 2 , an exhaust pipe 3 , a plasma reactor 4 , a power supply unit 5 , a control unit 6 , a catalyst temperature sensor 7 , and an A / F sensor 8 .

[0021] (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 inside as an example of a catalyst. The catalytic converter 2 uses the catalyst inside to decompose harmful components (hydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO)) contained in the exhaust gas.

[0022] (2) Exhaust pipe The exhaust pipe 3 is connected to the catalytic converter 2. The exhaust pipe 3 is connected downstream of the catalytic converter 2 in the direction in which the exhaust gas flows. The exhaust gas discharged from the engine 101 and passing through the catalytic converter 2 passes through the exhaust pipe 3 and is discharged outside the vehicle.

[0023] (3) Plasma reactor The plasma reactor 4 is disposed midway through 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.

[0024] More specifically, the plasma reactor 4 has a plurality of electrode panels 41. The plurality of electrode panels 41 are arranged at intervals 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 the electrode panels 41.

[0025] 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. The dielectric layer is made of a ceramic (dielectric) such as aluminum oxide.

[0026] When power is supplied to each electrode panel 41, a discharge (dielectric barrier discharge) occurs between each electrode panel 41. This causes the gas between each electrode panel 41 to become a plasma state. In other words, plasma is generated within the plasma reactor 4. Harmful components contained in the exhaust gas are then 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.

[0027] (4)Power supply device The power supply device 5 can supply power from the battery 102 to each electrode panel 41 of the plasma reactor 4. The power supply device 5 is electrically connected to the battery 102. The power supply device 5 is also 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. 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.

[0028] (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 Memory). The control device 6 is electrically connected to the battery 102. When the ignition switch of the vehicle 100 is turned on, the control device 6 is started up by receiving power from the battery 102.

[0029] The control device 6 is electrically connected to the power supply device 5. The control device 6 switches the power supply device 5 between an on state and an off state by sending a predetermined electrical 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.

[0030] The control device 6 is also electrically connected to an accelerator pedal (not shown). The control device 6 is capable of receiving an electric signal (accelerator instruction value) corresponding to the position of the accelerator pedal. The control device 6 is also electrically connected to a sensor (not shown) that measures the temperature of the coolant for the engine 101. The control device 6 is also electrically connected to a catalyst temperature sensor 7 and an A / F sensor 8.

[0031] (6) Sensor The catalyst temperature sensor 7 is attached to the catalytic converter 2. The catalyst temperature sensor 7 detects the temperature T (S / C) Measure.

[0032] The A / F sensor 8 is attached between the engine 101 and the catalytic converter 2. The A / F sensor 8 measures the oxygen concentration in the exhaust gas.

[0033] 2. Exhaust system control Next, the control of the exhaust system 1 will be described with reference to FIG.

[0034] When the ignition switch of the vehicle 100 is turned on, the control device 6 is activated. Furthermore, when the starter motor rotates, the engine 101 starts (S1). When the engine 101 starts, exhaust gas from the engine 101 flows into the catalytic converter 2.

[0035] However, immediately after the engine 101 starts, 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.

[0036] 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).

[0037] The particulate matter and hydrocarbons in the exhaust gas are then decomposed by the plasma reactor 4 .

[0038] The control device 6 detects the temperature T (S / C) If the temperature is lower than the catalyst activation temperature T1 (S3: NO), the plasma reactor 4 is maintained in the ON state.

[0039] The catalyst activation temperature T1 is the temperature at which the catalyst in the catalytic converter 2 is activated. The catalyst activation temperature T1 is, for example, 300°C.

[0040] And the temperature T in catalytic converter 2 (S / C) When the temperature reaches or exceeds the catalyst activation temperature T1, the catalyst in the catalytic converter 2 is activated. Therefore, the catalyst in the catalytic converter 2 can decompose the particulate matter and hydrocarbons in the exhaust gas.

[0041] Therefore, the temperature T (S / C) 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.

[0042] Therefore, the control device 6 causes the plasma reactor 4 to discharge when particulate matter needs to be treated, and stops the plasma reactor 4 from discharging when particulate matter does not need to be treated.

[0043] For details, the temperature T (S / C) When the catalyst activation temperature T1 or higher (S3: YES), the control device 6 determines whether the engine 101 is operating under conditions that may cause the generation of particulate matter (S4).

[0044] Specifically, whether or not the engine 101 is operating under conditions that are expected to generate particulate matter is determined from the temperature of the engine 101's coolant, the accelerator instruction value from the accelerator pedal (not shown), and the air-fuel ratio based on the A / F sensor 8.

[0045] In the following description, "air-fuel ratio" refers to the air-fuel ratio when the fuel is gasoline. When the air-fuel ratio is rich, it 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. When the air-fuel ratio is stoichiometric, it means that the air-fuel ratio is close to the stoichiometric air-fuel ratio.

[0046] Specifically, when the temperature of the engine 101 coolant is lower than a predetermined temperature, the accelerator instruction value is higher than a predetermined value, and the air-fuel ratio is rich, the control device 6 determines that the engine 101 is operating under conditions that are likely to generate particulate matter (S4: YES). In this case, since particulate matter needs to be treated, the control device 6 turns on the plasma reactor 4 (S5).

[0047] In other words, the temperature T (S / C) is equal to or higher than the catalyst activation temperature T1 (S3: YES) and the engine 101 is operating under conditions that are expected to generate particulate matter (S4: YES), the control device 6 causes the plasma reactor 4 to discharge (S5).

[0048] On the other hand, if the engine 101 is not operating under conditions that would likely result in the generation of particulate matter (S4: NO) and the air-fuel ratio is stoichiometric or rich (S6: NO), then there is no need to treat the particulate matter, and the control device 6 turns off the plasma reactor 4 (S7).

[0049] In other words, the temperature T (S / C)is equal to or higher than the catalyst activation temperature T1 (S3: YES), the engine 101 is operating under conditions where the generation of particulate matter is not expected (S4: NO), and the air-fuel ratio is stoichiometric or rich (S6: NO), the control device 6 stops the discharge of the plasma reactor 4 (S7).

[0050] This reduces the power consumption of the plasma reactor 4, thereby achieving energy conservation.

[0051] Furthermore, when the air-fuel ratio is not rich and oxygen is contained in the exhaust gas, if the plasma reactor 4 is discharged, 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.

[0052] After stopping the discharge of the plasma reactor 4, the control device 6 again determines whether or not the engine 101 is operating under conditions that are expected to generate particulate matter (S4).

[0053] If the engine 101 is not operating under conditions that would likely result in the generation of particulate matter (S4: NO) and the air-fuel ratio is lean (S6: YES), the control device 6 turns on the plasma reactor 4 (S8).

[0054] In other words, the temperature T (S / C) is equal to or higher than the catalyst activation temperature T1 (S3: YES), the engine 101 is operating under conditions where the 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).

[0055] When the air-fuel ratio is lean, the oxygen concentration in the exhaust gas is high. Therefore, by discharging electricity in the plasma reactor 4 when the air-fuel ratio is lean, the oxygen in the exhaust gas can be used to decompose the particulate matter adsorbed on the electrode panel 41 of the plasma reactor 4.

[0056] Then, when the engine 101 stops (S9: YES), the control device 6 turns off the plasma reactor 4 (S10).

[0057] If the engine 101 does not stop (S9: NO), the control device 6 again measures the temperature T (S / C) That is, the control device 6 continues to control the plasma reactor 4 until the engine 101 is stopped (S9: NO).

[0058] 3. Effects (1) According to the exhaust system 1, as shown in FIG. 2, the control device 6 causes the plasma reactor 4 to discharge when the engine 101 is operating under conditions in which the generation of particulate matter is expected (S4: YES), and when the engine 101 is operating under conditions in which the generation of particulate matter is not expected (S4: NO) and the air-fuel ratio is lean (S6: YES).

[0059] Therefore, when the engine 101 is operating under conditions where particulate matter is expected to be generated, the plasma reactor 4 discharges, thereby reducing the power consumed by the plasma reactor 4 and treating the particulate matter.

[0060] Furthermore, when the air-fuel ratio is lean, the plasma reactor 4 discharges, and oxygen in the exhaust gas is used to decompose the particulate matter adsorbed on the electrode panel 41 of the plasma reactor 4.

[0061] Therefore, oxygen is present in the exhaust gas, and by causing the plasma reactor 4 to discharge under conditions favorable for decomposing the particulate matter, the particulate matter adsorbed on the electrode panel 41 can be efficiently decomposed.

[0062] As a result, the particulate matter adsorbed on the electrode panel 41 can be treated while suppressing the power consumed by the plasma reactor 4.

[0063] (2) According to the exhaust system 1, as shown in FIG. 2, the discharge of the plasma reactor 4 can be stopped, thereby suppressing the power consumption of the plasma reactor 4.

[0064] Furthermore, when the air-fuel ratio is stoichiometric and oxygen is contained in the exhaust gas, if the plasma reactor 4 is discharged, nitrogen oxides (NOx) may be generated in the exhaust gas.

[0065] 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. [Explanation of symbols]

[0066] 1 Exhaust system 2 catalytic converters 3 exhaust pipe 4. Plasma Reactor 6. Control device

Claims

1. 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; Control device and Equipped with The control device The temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst inside the catalytic converter is activated, and the engine is operating under conditions that are expected to generate particulate matter; The temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst inside the catalytic converter is activated, the engine is operating under conditions where the generation of particulate matter is not expected, and the air-fuel ratio is lean. an exhaust system for discharging the plasma into the plasma reactor.

2. The control device 2. The exhaust system of claim 1, wherein the discharge of the plasma reactor is stopped when the temperature inside the catalytic converter is equal to or higher than the temperature at which the catalyst inside the catalytic converter activates, the engine is operating under conditions where particulate matter is not expected to be generated, and the air-fuel ratio is stoichiometric or rich.

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