WO2011114381A1

WO2011114381A1 - Exhaust gas evacuation device for internal combustion engine

Info

Publication number: WO2011114381A1
Application number: PCT/JP2010/001970
Authority: WO
Inventors: 宇野幸樹
Original assignee: トヨタ自動車株式会社
Priority date: 2010-03-18
Filing date: 2010-03-18
Publication date: 2011-09-22

Abstract

An exhaust gas evacuation device for an internal combustion engine, provided with: a bypass path (30) for connecting the air intake path (6), which is located on the downstream side of the supercharging device (7) of the internal combustion engine (1) of the vehicle, and the exhaust gas evacuation path (12) of the internal combustion engine (1); a bypass valve (33) for opening and closing the bypass path (30); and a controller (50) for controlling the bypass valve (33). The controller (50) causes intake air, which has been pressurized by the supercharging device (7), to be supplied to the exhaust gas evacuation path (12) by controlling the bypass valve (33) so that the temperature within a predetermined area including the end (23) of the exhaust gas evacuation path (12) is below a predetermined external reference value.

Description

Exhaust device for internal combustion engine

The present invention relates to an exhaust device having a function of reducing the exhaust temperature of an internal combustion engine.

It is desirable that the exhaust temperature outside the exhaust passage of the internal combustion engine is lower than a predetermined external reference value. As such an external reference value, for example, “300 ° C. or less at the outermost end of the vehicle (haystack fire standard)” and “180 ° C. or less at a point 300 mm from the outermost end of the vehicle (burn standard)” are used. There is.

In the exhaust system disclosed in Patent Document 1, in a configuration in which a three-way catalyst and a NOx catalyst are connected in series, in order to cool the NOx catalyst to a temperature suitable for purification, outside air is discharged immediately before the NOx catalyst in the exhaust passage by an air pump. Has been introduced.

In the exhaust system disclosed in Patent Document 2, a bypass passage is used to blow off unburned fuel and condensed water inside the low-pressure EGR passage in an intake and exhaust system having a turbocharger. The low-pressure EGR passage connects the downstream side of the turbine in the exhaust passage and the upstream side of the compressor in the intake passage. The bypass passage connects a midway portion of the low pressure EGR passage and a downstream side of the compressor in the intake passage. Air compressed by the pressure of the turbine is supplied to the low-pressure EGR passage through the bypass passage and discharged to the exhaust passage.

Japanese Patent Laid-Open No. 3-74513 Japanese Patent Laid-Open No. 11-125151

However, neither of the exhaust devices of Patent Document 1 and Patent Document 2 considers the influence of the exhaust temperature outside the exhaust passage on the outside.

An object of the present invention is to provide a novel means capable of suppressing the influence of the exhaust temperature outside the exhaust passage on the outside.

One embodiment of the present invention provides:
A bypass passage connecting an intake passage downstream of a supercharging device of an internal combustion engine of a vehicle and an exhaust passage of the internal combustion engine;
A bypass valve for opening and closing the bypass passage;
An exhaust system for an internal combustion engine comprising a controller for controlling the bypass valve,
The controller controls the bypass valve so that the temperature within a predetermined range including the end of the exhaust passage falls below a predetermined external reference value, and intake air pressurized by the supercharger is supplied to the exhaust passage. An exhaust device for an internal combustion engine to be supplied.

In this aspect, by opening the bypass valve, pressurized air is supplied from the intake passage on the downstream side of the supercharging device to the exhaust passage. The controller controls the bypass valve so that the temperature within a predetermined range including the end of the exhaust passage is lower than a predetermined external reference value. Therefore, the influence of the exhaust temperature outside the exhaust passage on the outside can be suppressed.

Preferably, the exhaust passage further includes a PM collection device that collects PM in the exhaust, the bypass valve is connected to the exhaust passage on the downstream side of the PM collection device, and the controller includes: The bypass valve is opened during the regeneration operation for burning or oxidizing the PM collected by the PM collection device. In this aspect, the influence of the exhaust temperature outside the exhaust passage on the outside can be suitably suppressed even during the regeneration operation in which the PM trapping device may be particularly hot.

In this case, preferably, the apparatus supplies a fuel supply device for supplying fuel into the exhaust passage to perform the regeneration operation, an ignition device for igniting the fuel supplied from the fuel supply device, Is further provided. In this aspect, even when the regeneration operation by fuel supply and ignition is performed, it is possible to suitably suppress the influence of the exhaust temperature outside the exhaust passage on the outside.

Preferably, the controller has a temperature at a predetermined position in the exhaust passage downstream of the PM collection device and downstream of the position where the bypass passage is connected exceeds a predetermined internal reference value. In some cases, the bypass valve is opened. In this aspect, the influence of the exhaust temperature outside the exhaust passage on the outside can be suitably suppressed even when the exhaust temperature outside the exhaust passage can be high, such as during or immediately after a high load. Can do.

Preferably, the controller opens the bypass valve when the traveling speed of the vehicle is smaller than a predetermined value. In this aspect, a situation in which an external object is easily affected by the exhaust temperature is avoided as much as possible. Therefore, the influence of the exhaust temperature outside the exhaust passage on the outside can be particularly preferably suppressed.

Preferably, the upstream end of the bypass passage is connected to the downstream side of the intercooler provided in the intake passage. In this case, since the intake air from the intake passage is cooled by the intercooler, the effect of the present invention can be realized particularly suitably.

In addition, the means for solving the problems in the present invention can be used in combination as much as possible.

According to the present invention, the influence of the exhaust temperature outside the exhaust passage on the outside can be suitably suppressed.

FIG. 1 is a conceptual diagram of a first embodiment of the present invention. FIG. 2 is a flowchart showing a bypass valve control process in the first embodiment. FIG. 3 is a graph showing an example of intake air temperature / internal reference value map setting in the second embodiment. FIG. 4 is a flowchart showing a bypass valve control process in the second embodiment. FIG. 5 is a conceptual diagram of the third embodiment. FIG. 6 is a graph showing a setting example of the bypass valve opening map in the modification.

<First Embodiment>
Preferred embodiments of the present invention will be described in detail below. FIG. 1 shows a first embodiment of the present invention. In FIG. 1, the engine body 1 is a compression ignition internal combustion engine (diesel engine) using light oil as fuel, but may be another type of internal combustion engine. Although the engine body 1 has the combustion chamber 2 in each of the four cylinders, the present invention is not limited to a four-cylinder engine. Each combustion chamber 2 is provided with an electronically controlled fuel injection valve 3 for injecting fuel. An intake manifold 4 and an exhaust manifold 5 are connected to the combustion chamber 2. The intake manifold 4 is connected to the outlet of the compressor 7 a of the exhaust turbocharger 7 via the intake pipe 6. An inlet of the compressor 7 a is connected to an air cleaner 9 via an air flow meter 8. The upstream side of the air cleaner 9 is open to the atmosphere.

In the intake pipe 6, a throttle valve 10 driven by a step motor is disposed. The actuator that drives the throttle valve 10 is not limited to a step motor, and other configurations such as a DC motor may be employed. An intercooler 11 for cooling the intake air flowing through the intake pipe 6 is disposed around the intake pipe 6. Engine cooling water is guided into the intercooler 11 and the intake air is cooled by the engine cooling water.

The exhaust manifold 5 is connected to the inlet of the exhaust turbine 7 b of the exhaust turbocharger 7. The outlet of the exhaust turbine 7 b is connected to the PM collection device 13 via the exhaust pipe 12. A small oxidation catalyst 14 is disposed in the engine exhaust passage upstream of the PM collection device 13, that is, in the exhaust pipe 12. The small oxidation catalyst 14 has a smaller volume than the PM collection device 13 and a part of the exhaust gas flowing into the PM collection device 13 flows. However, the present invention is not limited to the exhaust device provided with the small oxidation catalyst 14.

The PM collection device 13 and the small oxidation catalyst 14 are obtained by supporting an oxidation catalyst on a base material. The base material is, for example, a honeycomb structure made of porous ceramic, and the honeycomb structure is formed of a ceramic material such as cordierite, silica, or alumina. The base material includes a large number of gas passages each defined by a large number of partition walls and parallel to the flow direction of the exhaust gas. The base material of the PM collecting device 13 is a so-called wall flow type in which a first passage having a plug on the upstream side and a second passage having a plug on the downstream side are alternately formed. . The exhaust gas passes through the wall surface of the porous ceramic channel from the second passage clogged on the downstream side, flows into the first passage capped on the upstream side, and flows downstream. At this time, PM in the exhaust gas is collected by the porous ceramics, and release of PM into the atmosphere is prevented. On the other hand, the base material of the small oxidation catalyst 14 is a so-called flow-through type that does not have such plugging and has open end faces on the upstream side and the downstream side of the gas flow path. In addition, you may employ | adopt a structure different from this example, such as a grid | lattice form, as a base material. As the oxidation catalyst, for example, Pt / CeO ₂ , Mn / CeO ₂ , Fe / CeO ₂ , Ni / CeO ₂ , Cu / CeO ₂ or the like can be used.

In the exhaust pipe 12 upstream of the small oxidation catalyst 14, a fuel supply valve 15 for supplying fuel to the small oxidation catalyst 14 is arranged with its injection port facing the inside of the exhaust pipe 12. The fuel in the fuel tank 44 is supplied to the fuel supply valve 15 via the fuel pump 43. In order to promote combustion, a pipe line, a control valve, and a compressor for supplying combustion air into the exhaust pipe 12 from the outside may be provided.

A glow plug 16 is provided in the exhaust pipe 12 on the downstream side of the fuel supply valve 15. The glow plug 16 is arranged so that the fuel added from the fuel supply valve 15 is in contact with the tip portion which is the heat generating portion. The glow plug 16 is connected to a DC power source and a booster circuit (both not shown) for supplying power thereto. As a means for ignition, a ceramic heater may be used instead of the glow plug. In order to promote atomization of the fuel, a collision plate for colliding the fuel injected from the fuel supply valve 15 may be disposed in the exhaust pipe 12. The small oxidation catalyst 14, the fuel supply valve 15, and the glow plug 16 constitute an exhaust temperature raising device 40, which is controlled by an ECU 50 described later.

The exhaust manifold 5 and the intake manifold 4 are connected to each other via an EGR passage 18. An electronically controlled EGR control valve 19 is disposed in the EGR passage 18. Around the EGR passage 18, an EGR cooler 20 for cooling the EGR gas flowing in the EGR passage 18 is disposed. The engine cooling water is guided into the EGR cooler 20, and the EGR gas is cooled by the engine cooling water.

A NOx catalyst 21 and a silencer 22 are connected in series to the exhaust pipe 12 on the downstream side of the PM collection device 13. The NOx catalyst is, for example, an NOx storage reduction (NSR) catalyst, and a NOx absorption, such as platinum Pt as a catalyst component, on the surface of a base material made of an oxide such as alumina Al ₂ O _{3 and the} like. Components are supported. The NOx absorbing component is at least one selected from, for example, an alkali metal such as potassium K, sodium Na, lithium Li, and cesium Cs, an alkaline earth such as barium Ba and calcium Ca, and a rare earth such as lanthanum La and yttrium Y. It consists of one.

The NOx catalyst 21 absorbs NOx (nitrogen oxide) when the air-fuel ratio of the exhaust gas flowing into the exhaust gas is leaner than a predetermined value (typically the theoretical air-fuel ratio), and the NOx catalyst 21 in the exhaust gas flowing into the NOx catalyst 21 When the oxygen concentration decreases, the absorbed and released NOx soot is released. In this embodiment, since a diesel engine is used, the exhaust air-fuel ratio at normal times is lean, and the NOx catalyst 21 absorbs NOx in the exhaust. Further, when fuel as a reducing agent is supplied upstream of the NOx catalyst 21 and the air-fuel ratio of the inflowing exhaust gas becomes rich, the NOx catalyst 21 releases the absorbed NOx. The released NOx reacts with the reducing agent and is reduced and purified.

A tail pipe 23 constituting the end of the exhaust passage is connected to the downstream side of the silencer 22. The downstream side of the tail pipe 23 is open to the atmosphere.

The intake pipe 6 and the exhaust pipe 12 are connected via a bypass passage 30. The bypass passage 30 connects the intake pipe 6 downstream of the compressor 7 a of the exhaust turbocharger 7 and the exhaust pipe 12 downstream of the turbine 7 b and the PM collection device 13 and upstream of the NOx catalyst 21. Yes. The bypass passage 30 is provided with a bypass valve 33 that opens and closes the bypass passage 30. A known butterfly valve or poppet valve can be used as the bypass valve 33. The bypass valve 33 is driven by a step motor, but may be driven by other means such as a DC motor or a negative pressure actuator. When the bypass valve 33 is opened, the intake air pressurized by the compressor 7 a of the exhaust turbocharger 7 is supplied to the downstream side of the PM collection device 13.

A catalyst outlet temperature sensor 38 is installed in the intake pipe 12 downstream of the connection point with the bypass passage 30 and upstream of the NOx catalyst 21. The catalyst outlet temperature sensor 38 has a thermistor whose resistance value changes depending on the temperature, and can detect a change in the exhaust temperature based on a change in the resistance value of the thermistor.

Each fuel injection valve 3 is connected to a common rail 42 via a fuel supply pipe 41, and this common rail 42 is connected to a fuel tank 44 via an electronically controlled fuel pump 43 with variable discharge amount. The fuel stored in the fuel tank 44 is supplied into the common rail 42 by the fuel pump 43, and the fuel supplied into the common rail 42 is supplied to the fuel injection valve 3 through each fuel supply pipe 41.

An electronic control unit (ECU) 50, which is a controller, is composed of a well-known digital computer, and is connected to each other by a bidirectional bus, a ROM (read only memory), a RAM (random access memory), a CPU (microprocessor), an input port. And an output port.

The output signal of the catalyst outlet temperature sensor 38 is input to the input port of the ECU 50 via the corresponding AD converter. A load sensor 52 that generates an output voltage proportional to the amount of depression of the accelerator pedal 51 is connected to the accelerator pedal 51, and the output voltage of the load sensor 52 is input to the input port via a corresponding AD converter. Further, a crank angle sensor 53 that generates an output pulse every time the crankshaft of the engine body 1 rotates, for example, 15 ° is connected to the input port. Further, an intake air temperature sensor 54 installed near the throttle valve 10 and a vehicle speed sensor 55 installed near the drive wheel are connected to the input port.

On the other hand, the output port of the ECU 50 is connected to each step motor for driving the throttle valve 10, the EGR control valve 19, and the bypass valve 33 through corresponding drive circuits. The output port is also connected to the fuel injection valve 3 and the fuel pump 43 via corresponding drive circuits. The operation of these actuators is controlled by the ECU 50. Various programs and reference values / initial values are stored in the ROM of the ECU 50. Such reference values and initial values include a reference vehicle speed Va used in a bypass valve control process described later.

The ECU 50 calculates the fuel supply instruction amount based on parameters indicating the vehicle state, particularly the engine operating state, including the detected values of the air flow meter 8, the load sensor 52, and the crank angle sensor 53, and a time corresponding to the instruction amount. Only a control signal is output to open the fuel injection valves 3 and 15. In accordance with this control signal, an amount of fuel corresponding to the fuel supply instruction amount is supplied from the fuel injection valves 3 and 15.

Further, the ECU 50 controls the exhaust temperature raising device 40 to supply and ignite fuel, thereby selectively raising the temperature of the small oxidation catalyst 14. Part or all of the fuel supplied from the fuel supply valve 15 is ignited by the glow plug 16, thereby raising the temperature of the exhaust. A predetermined regeneration execution flag is provided in the RAM of the ECU 50, and the flag is turned on (1) while the regeneration operation is being performed, and is turned off (0) when the regeneration operation is not being performed. The ECU 50 supplies fuel to the PM collection device 13 by injecting more fuel than necessary for the small oxidation catalyst 14 as necessary, and thereby burns the accumulated particulate matter (PM). It is also possible to perform oxidation (regeneration operation) and NOx reduction processing and SOx poisoning recovery processing for the NOx catalyst 21.

During the regeneration operation, the temperature of the exhaust discharged from the PM collection device 13 is, for example, about 650 ° C. at the maximum. This value is an external reference value for the exhaust temperature, and is provided to suppress the risk of fire and burns (for example, “300 ° C or less at the outermost end of the vehicle (haystack fire standard)” and “outermost of the vehicle” It is higher than 180 ° C. or less (burn standard) at a point of 300 mm from the end. In contrast, the exhaust temperature in the exhaust manifold 5 of the engine body 1 is about 200 ° C. to about 300 ° C. during steady operation. While the exhaust gas flows through the exhaust gas turbocharger 7 and the exhaust pipe 12, the exhaust gas temperature is lowered by work and outside air cooling. Therefore, in a normal operation that is not being performed during the regeneration operation, the exhaust gas temperature is within a predetermined range including the end of the exhaust gas passage. The temperature of the above (for example, in a geometric region where it is considered that there is a low probability of fire or burns due to contact or thermal radiation outside the range, such as a point at the outermost end of the vehicle and 300 mm from the outermost end) It is considered to be sufficiently lower than the external standard value. If the bypass valve 33 is opened and the pressurized intake air is supplied to the exhaust pipe 12 during the regeneration operation, the temperature within a predetermined range including the end of the exhaust passage (tail pipe 23) is set to the external reference value. Will be lower.

The ECU 50 further executes the following bypass valve control process in parallel with the above-described controls. This bypass valve control process will be described with reference to FIG. The processing routine of FIG. 2 is repeatedly executed every predetermined time Δt on condition that an ignition switch (not shown) is turned on and the engine body 1 is operating. In FIG. 2, first, the ECU 50 reads the value of the regeneration execution flag described above and the vehicle speed detected by the vehicle speed sensor 55 (S10).

Next, the ECU 50 determines whether the regeneration operation is being executed based on the read regeneration execution flag value (S20). If NO, that is, if the regeneration operation is not being executed, the ECU 50 outputs a control to the step motor that drives the bypass valve 33 so as to close the bypass valve 33 (S50).

If the determination in step S20 is affirmative, that is, if the regenerating operation is being executed, then the ECU 50 determines whether the vehicle speed is lower than a predetermined reference vehicle speed Va based on the previously detected value of the vehicle speed sensor 55. Judgment is made (S30). The value of the reference vehicle speed Va is, for example, 10 km / h, a value obtained by adding a certain margin value to a speed that is considered to be unlikely to cause a fire or burn due to contact or thermal radiation at a higher speed. If negative, that is, if the vehicle speed is equal to or higher than the reference vehicle speed Va, the bypass valve 33 is closed (S50).

When the determination in step S30 is affirmative, that is, when the regenerating operation is being performed and the vehicle speed is smaller than the reference vehicle speed Va, the ECU 50 outputs a control to the step motor that drives the bypass valve 33 so as to open the bypass valve 33 ( S40). As a result, the air compressed by the pressure of the turbine 7 a is supplied into the exhaust pipe 12 through the bypass passage 30. With the above processing, the temperature within the predetermined range including the tail pipe 23 is lowered so as to be lower than the predetermined external reference value.

As described above, in the present embodiment, the bypass passage 30 connecting the intake pipe 6 on the downstream side of the compressor 7a of the exhaust injector 7 and the exhaust pipe 12 on the downstream side of the PM trap 13 and the bypass passage 30 are provided. Since the bypass valve 33 that opens and closes is provided, when the bypass valve 33 is opened, the pressurized air is supplied from the intake pipe 6 on the downstream side of the exhaust injector 7 to the exhaust pipe 12 on the downstream side of the PM collection device 13. To be supplied. The ECU 50 controls the bypass valve 33 so that the temperature within a predetermined range including the tail pipe 23 falls below a predetermined external reference value. Therefore, the influence of the exhaust temperature outside the exhaust passage on the outside can be suppressed.

The apparatus of the present embodiment further includes a fuel supply valve 15 that supplies fuel into the exhaust pipe 12 to perform a regeneration operation, and a glow plug 16 that ignites the fuel supplied from the fuel supply valve 15. Since it is provided, the influence of the exhaust temperature outside the exhaust passage on the outside can be suitably suppressed even when the regeneration operation by fuel supply and ignition is performed.

The ECU 50 opens the bypass valve 33 when the traveling speed of the vehicle is smaller than a predetermined value. Therefore, a situation in which an external object is easily affected by the exhaust temperature is avoided as much as possible, and the influence of the exhaust temperature outside the exhaust passage on the outside can be particularly preferably suppressed.

Second Embodiment
Next, a second embodiment of the present invention will be described. The second embodiment is characterized in that the bypass valve 33 is opened when the temperature at a predetermined position in the exhaust passage exceeds a predetermined internal reference value. In the second embodiment, an intake air temperature / internal reference value map as shown in FIG. 3 is created in advance and stored in the ROM of the ECU 50. The intake air temperature / internal reference value map stores the intake air temperature and the internal reference value Ta in association with each other, and the internal reference value Ta is set to be lower as the intake air temperature is higher. Since the remaining mechanical configuration of the second embodiment is the same as that of the first embodiment, a detailed description thereof will be omitted.

In the second embodiment, the ECU 50 executes the bypass valve control process shown in FIG. The processing routine of FIG. 4 is repeatedly executed every predetermined time on condition that an ignition switch (not shown) is turned on and the engine body 1 is operating. 4, the ECU 50 first reads the intake air temperature detected by the intake air temperature sensor 54, the catalyst outlet temperature detected by the catalyst outlet temperature sensor 38, and the vehicle speed detected by the vehicle speed sensor 55 (S110).

Next, the ECU 50 calculates the internal reference value Ta by referring to the intake air temperature / internal reference value map described above based on the read intake air temperature (S120). The value of the internal reference value Ta is, for example, 400 ° C. If the temperature is lower than that, a margin value from a temperature at which it is considered that there is a low probability of fire or burns due to contact or thermal radiation near the tail pipe 23. The value obtained by subtracting.

Next, the ECU 50 determines whether the catalyst outlet temperature is larger than the internal reference value Ta (S130). If negative, that is, if the catalyst outlet temperature is equal to or lower than the internal reference value Ta, the ECU 50 outputs a control to the step motor that drives the bypass valve 33 so as to close the bypass valve 33 (S160).

If the determination in step S130 is affirmative, that is, if the catalyst outlet temperature is greater than the internal reference value Ta, the ECU 50 next determines the reference vehicle speed at which the vehicle speed is determined in advance based on the detection value of the vehicle speed sensor 55 previously read. It is determined whether it is smaller than Va (S140). If negative, that is, if the vehicle speed is equal to or higher than the reference vehicle speed Va, the bypass valve 33 is closed (S160).

If the determination in step S140 is affirmative, that is, if the catalyst outlet temperature is higher than the internal reference value Ta and the vehicle speed is lower than the reference vehicle speed Va, the ECU 50 drives the bypass valve 33 so as to open the bypass valve 33. A control output is made to the motor (S150). As a result, the air compressed by the pressure of the turbine 7 a is supplied into the exhaust pipe 12 through the bypass passage 30. With the above processing, the temperature within the predetermined range including the tail pipe 23 is lowered so as to be lower than the predetermined external reference value.

As described above, in the present embodiment, the ECU 50 has a predetermined temperature (that is, a catalyst outlet temperature) at a predetermined position in the exhaust passage downstream of the PM collection device 13 and upstream of the tail pipe 23. When the internal reference value Ta is exceeded, the bypass valve 33 is opened. Therefore, the exhaust temperature outside the exhaust passage affects the outside not only in the catalyst regeneration operation but also in other operating states where the exhaust temperature outside the exhaust passage can be high, such as during high load driving or immediately after that. The influence can be suitably suppressed.

Further, in the present embodiment, the internal reference value Ta is dynamically set based on the intake air temperature, so that the bypass valve 33 is opened at a lower temperature as the outside air temperature is higher, and the influence of the exhaust temperature outside the exhaust passage on the outside. Can be suitably suppressed.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. As shown in FIG. 5, in the exhaust device of the third embodiment, the bypass passage 130 is connected to the downstream side of the intercooler 11 provided in the intake pipe 6.

In the third embodiment, since the intake air from the intake pipe 6 is cooled by the intercooler 11, the effect of the present invention can be realized particularly suitably.

Although the present invention has been described with a certain degree of specificity, it should be understood that various modifications and changes can be made without departing from the spirit and scope of the claimed invention. Embodiments of the present invention are not limited to the above-described embodiments, and the present invention includes all modifications and applications included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention. The means for solving the problems in the present invention can be used in combination as much as possible.

For example, in each of the above embodiments, the opening degree of the bypass valve 33 is set to the two states of full opening or full closing, but the opening degree of the bypass valve 33 is changed in a multistage or continuous manner between full opening and full closing. Also good. In this case, as shown in FIG. 6, for example, a bypass valve opening degree map in which, for example, the load and the EGR amount and the opening degree of the bypass valve 33 are defined is created in advance and stored in the ROM of the ECU 50. The opening degree of the bypass valve 33 may be changed by referring to the map. In this case, it is preferable to increase the opening degree of the bypass valve 33 as the load is increased and the EGR amount is decreased. In this case, the larger the load and the smaller the EGR amount, the larger the amount of intake air supplied from the bypass passage 30 and the better the exhaust gas is cooled. Therefore, the influence of the exhaust temperature outside the exhaust passage on the outside is preferable. Can be suppressed.

The position where the bypass passage 30 is connected to the exhaust pipe 12 may be between the NOx catalyst 21 and the silencer 22 or may be downstream of the silencer 22. The position in the exhaust passage where the temperature is acquired for comparison with the internal reference value may be between the blades downstream of the bypass passage 30 connected to the exhaust pipe, between the NOx catalyst 21 and the silencer 22. Further, it may be downstream of the silencer 22.

In each of the above embodiments, the bypass valve 33 is opened only when the vehicle speed is lower than the reference vehicle speed Va (S30, S140), but such a condition may not be provided. In the second embodiment, the internal reference value Ta is dynamically set. However, the internal reference value Ta may be a fixed value. The pm collection device may not carry a catalyst substance. A certain margin time or delay time may be provided between the end of the regeneration operation or when the catalyst outlet temperature falls below the internal reference value Ta until the bypass valve is closed. In each of the above embodiments, the fuel is supplied to the catalyst by the fuel injection valve 15 disposed in the exhaust passage. However, the fuel is supplied to the exhaust passage by so-called post injection (injection at a timing not accompanied by combustion, such as during an exhaust stroke). For example, the fuel injection valve 3 provided in the combustion chamber 2 may be used.

1 Engine Body 4 Intake Manifold 5 Exhaust Manifold 6 Intake Pipe 7 Turbocharger 12 Exhaust Pipe 13 PM Collection Device 14 Small Oxidation Catalyst 18 EGR Passage 30 Bypass Passage 33 Bypass Valve 40 Exhaust Temperature Raising Device 50 ECU

Claims

A bypass passage connecting an intake passage downstream of a supercharging device of an internal combustion engine of a vehicle and an exhaust passage of the internal combustion engine;
A bypass valve for opening and closing the bypass passage;
An exhaust system for an internal combustion engine comprising a controller for controlling the bypass valve,
The controller controls the bypass valve so that the temperature within a predetermined range including the end of the exhaust passage falls below a predetermined external reference value, and intake air pressurized by the supercharger is supplied to the exhaust passage. An exhaust system for an internal combustion engine to be supplied.
An exhaust system for an internal combustion engine according to claim 1,
A PM collecting device provided in the exhaust passage for collecting PM in the exhaust;
The bypass valve is connected to the exhaust passage on the downstream side of the PM collection device,
The exhaust device for an internal combustion engine, wherein the controller opens the bypass valve during a regeneration operation for burning or oxidizing the PM collected by the PM collection device.
An exhaust system for an internal combustion engine according to claim 2,
A fuel supply device for supplying fuel into the exhaust passage to perform the regeneration operation;
An ignition device for igniting the fuel supplied from the fuel supply device;
An exhaust system for an internal combustion engine, further comprising:
An exhaust system for an internal combustion engine according to claim 1,
The controller opens the bypass valve when a temperature at a predetermined position in the exhaust passage and downstream of the position where the bypass passage is connected exceeds a predetermined internal reference value. An exhaust system for an internal combustion engine.
An exhaust system for an internal combustion engine according to claim 1,
The exhaust system for an internal combustion engine, wherein the controller opens the bypass valve when the speed of the vehicle is smaller than a predetermined value.
An exhaust system for an internal combustion engine according to claim 1,
An exhaust system for an internal combustion engine, wherein an upstream end portion of the bypass passage is connected to a downstream side of an intercooler provided in the intake passage.