JP2013122209A - Internal combustion engine and control method for same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine and a control method for the same, capable of promoting the agitation and evaporation of an additive added to exhaust gas, and maintaining the temperature of a catalyst.SOLUTION: This internal combustion engine is provided with an urea injector 5 that adds urea water Ur to the exhaust gas Ga on the upstream side of an urea SCR catalyst 4 of the exhaust gas Ga post-treatment device 1. A mixer unit 13, through which exhaust gas Ga and urea water Ur added to the exhaust gas Ga pass while the exhaust gas and the urea water are agitated when a throttle valve 10 is opened, is provided to the throttle valve 10 of an exhaust throttle 6, which opens and closes an exhaust pipe 2 provided between the urea injector 5 and the urea SCR catalyst 4.

Description

  The present invention promotes stirring and evaporation of an additive added to exhaust gas, improves the uniformity of exhaust gas at a high exhaust gas flow rate, and maintains the catalyst at a low exhaust gas flow rate, and a control method thereof About.

  In a urea SCR (selective reduction) catalyst provided in a post-treatment device for treating exhaust gas, urea water is injected for NOx (nitrogen oxide compound) reduction, hydrolyzed into ammonia, and used as a reducing agent. The urea water is injected into the exhaust pipe by a urea injector (urea injection valve). However, stirring and evaporation do not proceed and the NOx purification rate is low.

  Therefore, a device that uses a mixer (also called a swirler) to improve the uniformity (a measure of the uniformity of the flow to the catalyst) by diffusing exhaust gas and to promote the evaporation of urea water. (For example, refer to Patent Document 1). However, when a normal mixer is used, the uniformity tends to decrease as the amount of exhaust gas increases. Ideally, if the diffusion effect is changed according to the amount of exhaust gas, the uniformity will not be reduced even if the amount of exhaust gas is large, but it is difficult because a normal mixer is not a variable structure. In addition, if a separate mixer is installed, the cost for installing the apparatus increases.

  On the other hand, there is also an apparatus using a pipe that devised the flow of exhaust gas. However, if the exhaust gas flow is devised by the layout of the exhaust pipe or the like to obtain the diffusion or evaporation effect of the exhaust gas flow, the layout itself may be restricted or an extra space may be required.

  In addition to the above problems, the urea water itself has a problem that the urea water precipitates as a solid substance at a specific temperature. In particular, this solid substance is likely to be deposited at a location where the flow rate is reduced, and if a mixer is provided, the solid matter accumulates at a location where the flow is stagnant, and the exhaust pipe is blocked.

JP 2007-077957 A

  The present invention has been made in view of the above problems, and its object is to reduce the cost and to promote the stirring and evaporation of the additive added to the exhaust gas. It is to provide an internal combustion engine that can keep the temperature of the catalyst device at a low exhaust gas flow rate, and a control method therefor. Another object of the present invention is to provide an internal combustion engine that can prevent solidification of the additive and a control method thereof.

  An internal combustion engine of the present invention for solving the above object includes an exhaust gas aftertreatment device including a catalyst device in an exhaust passage, and an addition valve for supplying an additive to the exhaust gas upstream of the catalyst device, The exhaust gas and the additive added to the exhaust gas are passed through the valve device that is provided between the addition valve and the catalyst device and opens and closes the exhaust passage while the valve device is opened. A stirrer is provided.

According to this configuration, the exhaust gas in which the additive is added to the exhaust gas can be stirred to diffuse the additive. In addition, the uniformity of the flow of the exhaust gas that has passed through the stirring unit to the catalyst device can be improved. In particular, when urea water is added to the exhaust gas as an additive, the urea water can be stirred to promote evaporation, so that the NOx purification rate can be improved.

  Further, in the internal combustion engine, the valve device is formed by a butterfly valve, and the stirring unit is formed by a stirring plate that extends to the entire exhaust passage when the butterfly valve is fully opened, and is provided on the stirring plate. If the circulation port is equipped with a stirring blade that changes the degree of stirring of the exhaust gas and the additive added to the exhaust gas depending on the valve opening of the butterfly valve, the stirring blade of the stirring unit changes the degree of stirring depending on the opening of the valve device. The stirring effect can be changed according to the change in the flow rate of the exhaust gas.

  In addition, in the internal combustion engine described above, when the valve device is formed by an exhaust brake valve of an exhaust brake device, it is only necessary to add the above-described stirring unit to the exhaust brake valve, there is no increase in device space, and the installation position The degree of freedom in design can be increased, and urea water and HC addition can be stirred at a slight cost increase, and evaporation of these additives can be promoted. In addition, since the opening of the valve changes according to the exhaust gas emissions (running conditions), it is possible to prevent a decrease in uniformity at high exhaust gas flow rates, and to reduce exhaust gas flow rates at low exhaust gas flow rates. The catalyst can be kept warm. In addition, since the agitating part moves in conjunction with the exhaust brake valve, the part where the flow velocity is low can be changed to prevent the additive from solidifying, and even if solidification occurs, the exhaust valve During operation, it can fall off and be discharged.

  In addition, in the internal combustion engine, when the catalyst device is formed of a urea selective catalyst device and the addition valve is formed of a urea injection valve, urea water is stirred by the stirring blades of the stirring portions on the upper and lower surfaces of the valve device. In addition, since evaporation is promoted and supplied to the urea SCR device, the NOx purification rate can be improved. In addition, since the urea SCR device can be kept warm when the valve device is fully closed, the urea water is prevented from precipitating as a solid substance, and the urea water crystallized and volume in the agitating portion is opened and closed by the opening and closing operation of the valve device. Can be eliminated. Thereby, the progress of crystallization of urea water in the urea SCR device and the stirring unit can be prevented.

  In addition, an internal combustion engine control method for solving the above problem is provided with an exhaust gas aftertreatment device including a catalyst device in an exhaust passage of the internal combustion engine, and an additive for supplying an additive to the exhaust gas upstream of the catalyst device In a control method for an internal combustion engine, which includes a valve and a valve device that opens and closes the exhaust passage between the addition valve and the catalyst device, closing the valve device shields exhaust gas and opens the valve device. In other words, the exhaust gas and the additive added to the exhaust gas are allowed to pass through the stirring unit provided in the valve device while stirring.

  According to this method, when the valve device is opened, the urea water and the added HC can be stirred, and the evaporation of these additives can be further promoted. Further, when the valve device is closed, no exhaust gas flows through the catalyst, so that the catalyst can be prevented from being cooled and the catalyst can be kept warm.

  Further, in the above control method for an internal combustion engine, when the exhaust gas flow rate is high, the valve device is fully opened, and when the exhaust gas flow rate is low, the valve device is closed from the fully open position, and fuel is not supplied to the internal combustion engine. When fully closed, the uniformity at high load can be improved as a high diffusion effect at a high exhaust gas flow rate and a low diffusion effect at a low exhaust gas flow rate. During deceleration, the amount of gas flowing through the catalyst can be reduced to prevent cooling of the catalyst. When idling, the exhaust gas flow passes through the agitation unit, and the agitation and evaporation of the additive are promoted. Although the pressure loss increases, the exhaust pressure has hardly increased originally in the idling state, so there is no problem and the catalyst can be kept warm during idling.

According to the present invention, the stirring and evaporation of the additive added to the exhaust gas can be promoted at low cost, and the uniformity of the exhaust gas can be improved at a high exhaust gas flow rate. Sometimes the catalyst device can be kept warm. Moreover, solidification of the additive added to the exhaust gas can be prevented.

It is the schematic which showed the exhaust system of the internal combustion engine of 1st Embodiment which concerns on this invention. It is the perspective view which showed the exhaust throttle shown in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, showing a fully opened state of the exhaust throttle. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, showing a fully closed state of the exhaust throttle. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, and is a cross-sectional view showing an intermediate opening state between the exhaust throttle fully opened and fully closed. It is the schematic which showed the internal combustion engine of 2nd Embodiment which concerns on this invention. It is the flowchart which showed the control method of the internal combustion engine of embodiment which concerns on this invention.

  Hereinafter, an internal combustion engine and a control method thereof according to embodiments of the present invention will be described with reference to the drawings. This embodiment will be described by taking a diesel engine as an example, but the present invention is not limited to a diesel engine but can be applied to a gasoline engine, and the number of cylinders and the arrangement of cylinders are not limited. Note that the dimensions of the drawings are changed so that the configuration can be easily understood, and the ratios of the thicknesses, widths, lengths, and the like of the respective members and parts do not necessarily match the ratios of actually manufactured parts.

  First, an internal combustion engine according to a first embodiment of the present invention will be described with reference to FIG. The engine (internal combustion engine) is provided with a post-processing device 1 that processes exhaust gas Ga generated by fuel combustion. The aftertreatment device 1 includes a DPF (diesel particulate collection filter) 3 and a urea SCR catalyst (urea selective reduction catalyst) 4 in an exhaust pipe 2. A urea injector (urea injection valve) 5 is provided upstream of the urea SCR catalyst 4.

  In addition, an exhaust throttle (valve device) 6 is provided upstream of the urea SCR catalyst 4 and downstream of the urea injector 5. The engine further includes an ECU (control device) 7 and a displacement sensor 8. The ECU 7 performs injection control of the urea injector 5 and opening / closing control of the exhaust throttle 6 based on the exhaust gas flow rate detected by the exhaust amount sensor 8. In this control, it suffices if the exhaust gas flow rate can be calculated, and another sensor may be used instead of the exhaust gas sensor 8, and the exhaust gas flow rate is calculated from the intake air amount and the fuel injection amount sucked into the engine. A calculation method may be used.

  The exhaust throttle 6 includes a link mechanism 6a, an air chamber 6b, and a throttle valve 10. When the throttle valve 10 is fully closed, the exhaust throttle 6 shields the exhaust pipe 2 and causes the exhaust gas Ga to stay on the upstream side of the exhaust throttle 6, and opens from the fully closed state, whereby the exhaust gas Ga is passed to the urea SCR catalyst 4. It is not limited to the above configuration as long as it can flow.

  Next, the throttle valve 10 which is a feature of the present invention will be described with reference to FIG. The throttle valve 10 includes a butterfly valve 11 and a rotating shaft 12, and includes a mixer unit (stirring unit) 13 on both sides of the butterfly valve 11. The mixer unit 13 includes a mixer plate (stirring plate) 14, a distribution port 15, and It comprises a plurality of fins (stirring blades) 16a to 16c.

  In this embodiment, the butterfly valve 11 is used as a valve body for opening and closing the exhaust pipe 2 of the throttle valve 10. However, the valve body is not limited to the butterfly valve as long as the inside of the exhaust pipe 2 can be opened and closed. The thing which can provide the mixer part 13 in is preferable. Further, it is sufficient that the opening can be fixed to at least fully open and fully closed, but it is preferable that the opening can be fixed to fully open, fully closed, and an intermediate opening therebetween, and the opening can be set at an arbitrary position, and What can fix the opening degree is more preferable.

  Further, an opening degree threshold is set to prevent damage to the urea SCR catalyst 4 and a turbocharger (not shown) due to an increase in pressure loss when the throttle valve 10 is closed with respect to the exhaust gas flow rate. However, the exhaust pipe 2 cannot be closed completely, but here, the state will be described as a fully closed state.

  The mixer section 13 is desirably shaped so as not to interfere with the exhaust pipe 2 when the butterfly valve 11 is opened and closed, and to obtain as large an area as possible and with a small increase in pressure loss. The shape of 16c (hereinafter referred to as fin 16) is preferably such that the degree of agitation changes according to the opening of butterfly valve 11. That is, it is preferable that the mixer section 13 has a large mixer effect when the amount of closing of the butterfly valve 11 is small (when the exhaust gas flow rate is high) and a small mixer effect when the amount of closure is large (when the exhaust gas flow rate is low). .

  An example of the mixer unit 13 will be described. Mixer plates 14 are provided on both sides of the butterfly valve 11 so that when the butterfly valve 11 is fully opened, the mixer plate 14 is formed so as to spread over the entire exhaust passage, and a flow port 15 having a wide opening area is provided so as not to reduce the flow rate of exhaust gas. .

  Preferably, when the butterfly valve 11 is fully opened, the both sides are formed so as to have substantially the same shape as the cross section of the exhaust pipe 2. If the mixer plate 14 is formed in the same shape as the cross section of the exhaust pipe 2, it does not interfere with the exhaust pipe 2 during opening and closing. Further, when the mixer plate 14 is disposed so that the surface of the mixer plate 14 is inclined with respect to the exhaust gas shielding surface of the butterfly valve 11, interference with the exhaust pipe 2 can be further prevented, and when the exhaust throttle 10 is fully opened, The opening area of 15 can be increased.

  The fin 16 is formed of a plate having a crescent-shaped cross section. The shape of the fins 16 is not limited as long as the diffusion effect changes depending on the opening of the butterfly valve 11, and more preferably, the angle with respect to the flow of exhaust gas when the butterfly valve 11 is fully opened. And the butterfly valve 11 may have a shape that is substantially parallel to the flow of exhaust gas when the butterfly valve 11 has an opening between the fully open and fully closed positions.

  The operation of the engine of this embodiment will be described with reference to the operation of the exhaust throttle 10 shown in FIGS. Here, when combustion occurs in a cylinder (not shown) of the engine and the exhaust gas Ga flows through the exhaust pipe 2 (during normal traveling of the vehicle), exhaust gas is generated and discharged from the exhaust valve. In the exhaust gas Ga flowing through the exhaust pipe 2, the flow at the center of the exhaust pipe 2 is stronger than the vicinity of the inner wall of the exhaust pipe 2. Further, the exhaust gas Ga to which the urea water Ur is added from the urea injector 5 provided upstream of the throttle valve 10 is not stirred, and the urea water Ur is not diffused.

  Therefore, during normal traveling of the vehicle, as shown in FIG. 3, the opening is fully opened at a high exhaust gas flow rate, and the opening is smaller than the fully opened opening at a low exhaust gas flow rate. In this way, by changing the opening degree of the throttle valve 10 according to the exhaust gas flow rate detected by the exhaust gas amount sensor 8, the mixer effect by the fins 16 is increased at a high exhaust gas flow rate, and the mixer effect is increased at a low exhaust gas flow rate. Can be small.

  The inclination of the fin 16 is provided to have an angle α with respect to the direction in which the exhaust gas flows. This gradient α becomes maximum when the exhaust throttle 10 is fully opened, and becomes smaller in proportion to the decrease in the opening degree. During normal running of the engine 1, the shape and attachment of the fins 16 may be adjusted so that the inclination α is 10 ° to 80 °.

  When the exhaust throttle 10 is fully open, the flow path resistance of the butterfly valve 11 itself disappears, but the fin 16 of the mixer section 13 has an angle α with respect to the flow of the exhaust gas Ga. Occur. Therefore, when the inclination α of the fin 16 with respect to the exhaust gas Ga is set, it is desirable that the maximum mixer effect be obtained within the allowable range of the increase in resistance.

  When the engine is fuel cut and combustion does not occur in the cylinder and the exhaust gas Ga does not flow in the exhaust pipe 2 (when the vehicle is decelerated), as shown in FIG. 4, the throttle valve 10 is closed, The amount of gas flowing through the urea SCR catalyst 4 can be reduced to prevent the urea SCR catalyst 4 from being cooled. At this time, since the exhaust gas Ga is not generated because the fuel is cut, control is performed so that urea water is not injected from the urea injector 5.

  When the throttle valve 10 is fully closed during deceleration of the vehicle, it is possible to prevent a relatively low temperature gas from passing through the urea SCR catalyst 4 and to prevent the urea SCR catalyst 4 from being cooled at that time. Thereby, the urea SCR catalyst 4 can be kept warm. This operation can also be applied when the vehicle is idling stopped.

  When the engine is rotating when the vehicle is stopped, such as when the vehicle is parked or stopped, or when waiting for a signal, the opening of the throttle valve 10 is set to an intermediate opening between fully open and fully closed as shown in FIG. . At this time, the inclination of the fin 16 is preferably substantially parallel to the direction in which the exhaust gas Ga flows. Since the exhaust gas Ga passes through the mixer section 13 of the throttle valve 10, stirring and evaporation of the exhaust gas Ga and the added urea water Ur can be promoted from the fins 16 of the mixer section 13.

  Although the pressure loss increases as compared with the fully opened state, the exhaust pressure does not substantially increase in the idling state and there is no problem. Further, in the idle state, the temperature of the exhaust gas Ga is lower than that during normal traveling. Therefore, the amount of exhaust gas flowing to the urea SCR catalyst 4 is reduced by setting the opening to an intermediate opening, so that the urea SCR catalyst 4 is also kept warm. can do.

  The above operation is an operation when the throttle valve 10 capable of freely changing the opening degree is used, but when the opening degree cannot be changed freely, the fully open state during idling, idling It is good to use it properly depending on the effect as fully open or fully closed.

  According to the above operation, the exhaust gas Ga to which the urea water Ur is added upstream of the exhaust throttle 6 can be stirred by the mixer unit 13 provided in the throttle valve 11 to promote the evaporation of the urea water Ur. In addition, the NOx purification rate of the urea SCR catalyst 4 can be improved.

  In addition, since the mixer effect can be changed in accordance with the change in the flow rate of the exhaust gas Ga, particularly when the exhaust gas flow rate is high, if the fin 16 has an angle α with respect to the flow of the exhaust gas Ga, The mixer effect (stirring effect) can be strengthened at a high flow rate, and the uniformity can be prevented from decreasing particularly at a high flow rate. Thereby, even when the exhaust gas flow rate is high, the exhaust gas Ga can be diffused without reducing the uniformity.

In addition, since the throttle valve 10 is opened and closed by the exhaust gas flow rate, it is possible to solve the problem that the urea water Ur is crystallized and volume in the mixer unit 13. Even if the urea water Ur is crystallized and volumed, it can be removed during the operation of the throttle valve 10, so that the progress of crystallization can be prevented.

  Further, when the exhaust gas temperature is relatively low and the exhaust gas flow rate is low, the exhaust gas flow rate to the urea SCR catalyst 4 can be reduced by fully closing or reducing the opening, so that the urea SCR catalyst 4 is kept warm. be able to. Thereby, it is possible to prevent the urea water Ur from being crystallized and deposited by the urea SCR catalyst 4.

  The exhaust throttle 6 can achieve the same effect even when HC (light oil) is added to the exhaust gas Ga. For example, if the post-treatment device 1 is provided with a deNOx catalyst and an HC addition valve upstream of the deNOx catalyst, and the exhaust throttle 6 is provided upstream of the deNOx catalyst and downstream of the HC addition valve, it is added to the exhaust gas. Since the evaporated HC can be stirred to promote evaporation, the rich reduction of the LNT catalyst, the reduction during the S purge (SOx release control), and the PM regeneration rate can be improved.

  Next, an engine according to a second embodiment of the present invention will be described with reference to FIG. The engine (internal combustion engine) 20 includes an exhaust passage 22 and an intake passage 23 in an engine body 21, and the post-processing device 1 described above is provided in the exhaust passage 22. A turbocharger or an EGR device (exhaust gas recirculation device) may be provided between the exhaust passage 22 and the aftertreatment device 1. Further, the intake passage 23 is provided with a MAF sensor (intake air amount sensor) 24 for detecting the intake air amount (MAF value).

  The exhaust throttle 6 described above is connected to an exhaust brake system (also called an exhaust retarder) 30 and operates as an exhaust brake valve. When the exhaust throttle 6 is closed, the exhaust pressure of the exhaust pipe 2 and the exhaust passage 22 increases. The pumping loss of the engine body 21 can be made larger than usual to suppress the rotational speed.

  The exhaust brake system 30 is an electro-pneumatic exhaust brake in which an air valve mechanism 31 sends compressed air from an air tank 32 to an air chamber 6b and opens and closes the exhaust throttle 6 as an exhaust brake valve via the link mechanism 6a.

  The exhaust brake system 30 includes an operation unit 33, and includes an accelerator pedal 34, a brake switch 35, a clutch switch 36, and an accelerator switch 37. The exhaust brake system 30 is activated only when the ECU 7 detects that the accelerator pedal 34 or both clutch pedals (not shown) are not depressed, that is, the accelerator switch 37 or the clutch switch 36 is not turned on. It is configured to run.

  In the case of a commercial vehicle such as a truck, the exhaust brake system 30 is often originally installed, and the mixer section 13 having the fins 16 described above is provided on the throttle valve 10 of the exhaust brake system 30 that is originally installed. It is only necessary to provide it, and the above-described effects can be obtained with a slight increase in manufacturing cost. On the other hand, passenger cars usually do not have the exhaust brake system 30, but the amount of precious metal in the catalyst can be reduced due to the catalyst temperature increasing effect due to the catalyst heat retention effect described above. Even if 30 is mounted, the overall cost is small.

  Next, a method for controlling the engine 20 will be described with reference to a flowchart shown in FIG. Based on this control method, the ECU 7 controls each device. First, step S <b> 1 is performed to determine whether or not the traveling state of the vehicle is normal traveling. The normal running here means a state in which fuel is injected and burned by the engine body 21.

  As a method of determining the traveling state of the vehicle, there is a method of determining from the operation signal of the operation unit 33 such as the accelerator pedal 34. Normally, since the ECU 7 calculates the fuel injection amount based on the opening degree of the accelerator pedal 34, a method of determining this step S1 based on the opening degree of the accelerator pedal 34 may be used. It can also be determined from the values of various sensors connected to the ECU 7.

  If it is determined that the traveling state of the vehicle is during normal traveling, then step S2 for calculating the exhaust gas flow rate is performed. In step S <b> 2, the exhaust gas flow rate is calculated from the command fuel injection amount determined by the ECU 7 from the opening of the accelerator pedal 34 and the air intake amount detected by the MAF sensor 24. In this step S2, it is only necessary to be able to calculate the exhaust gas flow rate, and the exhaust gas flow rate may be calculated from the above-described exhaust amount sensor, lambda sensor, or A / F sensor, for example, without being limited to the above method. .

  Next, step S3 which opens the exhaust throttle 6 with the opening according to the amount of exhaust gas is performed. In step S3, as described in FIG. 3, the throttle valve 10 of the exhaust throttle 6 is opened. The opening degree of the throttle valve 10 corresponding to the exhaust gas flow rate is selected with reference to an opening degree map M1 stored in advance in the ECU 7 and based on the exhaust gas flow rate and the opening degree of the throttle valve 10.

  The opening degree map M1 is determined so that the opening amount is large when the exhaust gas flow rate is high, and the opening amount is small when the exhaust gas flow rate is low, and an optimum mixer effect can be obtained within the range. It is a map. When the throttle valve 10 is opened at an opening corresponding to the exhaust gas flow rate in step S3, the process returns to the start again as shown in FIG.

  On the other hand, if it is determined in step S1 that the vehicle driving state is not during normal driving, then step S4 is performed to determine whether or not the vehicle driving state is during deceleration. In step S4, the determination can be made in the same manner as in step S1.

  If it is determined that the running state of the vehicle is during deceleration, then step S5 for fully closing the exhaust throttle 6 is performed. In step S5, as explained in FIG. 4, when the throttle valve 10 of the exhaust throttle 6 is fully closed, the flow of the exhaust gas Ga is cut off, the exhaust pressure is applied to the engine body 21, the pumping loss is increased, and the rotation Speed can be suppressed. When the exhaust throttle 6 is fully closed in step S5, the process returns to the start again as shown in FIG.

  On the other hand, if it is determined in step S4 that the running state of the vehicle is not decelerated, step S6 is performed to determine whether the running state of the vehicle is idle. This step S6 can also be determined by the same method as step S1 and step S4.

  In this step S6, it is determined whether or not the engine 30 is idling. If the vehicle has an idling stop system and is configured to stop the engine 30 when the vehicle is temporarily stopped, the step S6 is changed. Can be omitted.

  If it is determined that the running state of the vehicle is idle, then step S7 is performed to fix the exhaust throttle 6 to an intermediate opening degree between full open and full close. In step S7, as described in FIG. 5, the throttle valve 10 is fixed at an intermediate opening. When step S7 is completed, the process returns to the start again as shown in FIG. Similarly, if it is determined in step S6 that the vehicle is not in an idling state, the process similarly returns to the start. This control method is similarly performed until the vehicle is completely stopped.

  According to the above control method, in addition to the operational effect obtained by changing the opening degree of the throttle valve 10 of the exhaust throttle 6 according to the exhaust gas flow rate, the exhaust throttle 6 operates as an exhaust brake valve of the exhaust brake system 30. Therefore, since the location where the flow rate is low also changes, solidification of urea water hardly occurs. Even if solidification occurs, the exhaust throttle 6 is peeled off and discharged, so that the problem associated with solidification of urea water can be solved as compared with the conventional mixer.

  The internal combustion engine of the present invention is simply provided with a stirrer that can stir the exhaust gas and the additive added to the exhaust gas in the valve body of the conventional exhaust brake system. Evaporation can be promoted and the uniformity of exhaust gas can be improved. On the other hand, when the exhaust gas flow rate is low, the catalyst can be kept warm by preventing relatively low temperature exhaust gas from flowing into the catalyst. Therefore, it can be used for vehicles such as trucks equipped with exhaust brakes.

1 Exhaust system 2 Exhaust pipe 3 DPF
4 Urea SCR catalyst (catalyst device)
5 Urea injector (addition valve)
6 Exhaust throttle (valve device)
7 ECU (control device)
DESCRIPTION OF SYMBOLS 10 Throttle valve 11 Butterfly valve 13 Stirring part 16a-16c Fin 20 Engine (internal combustion engine)
30 Exhaust brake system The valve device is fully opened at a high exhaust gas flow rate, the valve device is closed from the full open at a low exhaust gas flow rate, and fully closed when fuel is not supplied to the internal combustion engine. The method for controlling an internal combustion engine according to claim 5.

Claims (6)

An exhaust gas aftertreatment device including a catalyst device is provided in the exhaust passage, an addition valve for supplying an additive to the exhaust gas is provided on the upstream side of the catalyst device, and
Stirring that allows the exhaust gas and the additive added to the exhaust gas to pass through the valve device that opens and closes the exhaust passage provided between the addition valve and the catalyst device while stirring the valve device. An internal combustion engine comprising a portion. The valve device is formed by a butterfly valve;
The stirring unit is formed by a stirring plate that extends over the entire exhaust passage when the butterfly valve is fully opened, and is added to the exhaust gas and the exhaust gas by a valve opening of the butterfly valve at a flow port provided in the stirring plate. The internal combustion engine according to claim 1, further comprising a stirring blade that changes a stirring degree of the additive.   The internal combustion engine according to claim 1 or 2, wherein the valve device is formed by an exhaust brake valve of an exhaust brake device.   The internal combustion engine according to any one of claims 1 to 3, wherein the catalyst device is formed of a urea selective catalyst device, and the addition valve is formed of a urea water injection valve. An exhaust gas aftertreatment device including a catalyst device is provided in an exhaust passage of the internal combustion engine, an addition valve for supplying an additive to the exhaust gas is provided upstream of the catalyst device, and the exhaust gas is provided between the addition valve and the catalyst device. In a control method of an internal combustion engine comprising a valve device for opening and closing a passage,
When the valve device is closed, the exhaust gas is shielded,
A control method for an internal combustion engine, wherein when the valve device is opened, the exhaust gas and the additive added to the exhaust gas are allowed to pass through the stirring unit provided in the valve device while stirring.   The valve device is fully opened at a high exhaust gas flow rate, the valve device is closed from the full open at a low exhaust gas flow rate, and fully closed when fuel is not supplied to the internal combustion engine. 6. A method for controlling an internal combustion engine according to 5.