JP2016142192A - Intake/exhaust device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel economy, and to shorten a warmup time of a catalyst.SOLUTION: An exhaust turbine 5 comprises a flow rate adjustment valve 17 which opens and closes a second exhaust scroll 22, and a waste gate valve 18 which opens and closes a bypass passage. A first exhaust passage 21 employs a constantly-opened constitution. When a catalyst 15 is warmed up in an initial stage, the flow rate adjustment valve 17 is closed, and the waste gate valve 18 is fully opened. By this constitution, since a rise of the exhaust pressure of the exhaust turbine 5 at an upstream side of the exhaust turbine 5 can be suppressed, a pumping loss can be reduced, and fuel economy can be improved. Furthermore, when the catalyst 15 is warmed up in an initial stage, since an exhaust gas flows in a first exhaust scroll 21, it can be prevented that a drift of the exhaust gas is formed in the exhaust turbine, and also it can be prevented that a disturbance of a flow of the exhaust gas generated by the drift deprives the exhaust gas of heat to the exhaust turbine 5. By this constitution, fuel economy can be improved, and a warmup time of the catalyst can be shortened.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an intake / exhaust device for an internal combustion engine in which an exhaust turbine of a turbocharger is disposed on the exhaust upstream side of a catalyst for purifying exhaust gas.

(Conventional technology)
There is known an intake / exhaust device for an internal combustion engine in which an exhaust turbine is disposed on the exhaust upstream side of a catalyst (see, for example, Patent Document 1).
In order to purify the exhaust gas with the catalyst, it is necessary to raise the temperature of the catalyst to the activation temperature.
The catalyst is heated by the heat of the exhaust gas. For this reason, in order to increase the exhaust gas purification capacity immediately after the cold start of the internal combustion engine (hereinafter referred to as the engine), it is necessary to quickly heat the catalyst with the exhaust gas immediately after the start.
However, in a vehicle equipped with a turbocharger, since an exhaust turbine existing upstream of the catalyst has a large heat capacity, it takes time to raise the catalyst to the activation temperature.

In order to avoid the problem, Patent Document 1 discloses a waste gate that closes an exhaust passage (exhaust scroll) that guides exhaust gas to an exhaust turbine when the catalyst is warmed up early (such as during cold start). A technique is disclosed in which a valve is opened and exhaust gas is allowed to flow only through a bypass passage (a passage opened by a wastegate valve).
In other words, the technology of Patent Document 1 allows the exhaust gas to flow only through the bypass passage, thereby preventing the heat of the exhaust gas from being taken away by the exhaust turbine as much as possible, and heating the catalyst early with the high-temperature exhaust gas that suppresses the temperature drop. It is something to be made.

(Problem 1 of the prior art)
In the technique of Patent Document 1, when the catalyst is warmed up early, the exhaust passage is closed, the wastegate valve is opened, and the exhaust gas is allowed to flow only through the bypass passage.
For this reason, the bypass passage which is the only passage for the exhaust gas acts as a bottleneck of the exhaust gas, and the exhaust pressure on the upstream side of the exhaust turbine rises. Then, the pumping loss of the engine is increased, and the fuel consumption is deteriorated.

(Problem 2 of the prior art)
In the technique of Patent Document 1, the means for closing the exhaust passage when the catalyst is warmed up early is a movable flap provided at the outlet of the exhaust scroll.
For this reason, when the exhaust passage is fully closed by the movable flap, the exhaust gas is blown up in the exhaust passage existing on the upstream side of the movable flap, and the flow of the exhaust gas is disturbed in the exhaust turbine. As a result, there is a problem that heat transfer from the exhaust gas to the exhaust turbine increases, and the exhaust turbine takes a large amount of heat of the exhaust gas, thereby delaying the early warm-up of the catalyst.

JP-A-4-370327

  The present invention has been made in view of the above problems, and its purpose is to improve fuel efficiency by suppressing pumping loss and (ii) exhaust gas when warming up the catalyst early. The present invention is to provide an intake / exhaust device for an internal combustion engine that can reduce the warm-up of the catalyst early by suppressing the heat of the exhaust gas from being taken away by the exhaust turbine.

The intake / exhaust device for an internal combustion engine according to the present invention is configured such that the first exhaust scroll is always opened. When the catalyst is warmed up early, the second exhaust scroll is closed by the flow rate adjusting valve and the waste gate valve is used. Open the bypass.
(I) When the catalyst is warmed up early, the exhaust gas flows to both the first exhaust scroll and the bypass passage, so that the exhaust pressure on the upstream side of the exhaust turbine can be reduced as compared with the prior art. For this reason, the pumping loss of the engine can be suppressed, and fuel consumption can be improved.

(Ii) Further, when the catalyst is warmed up early, the heat of the exhaust gas can be made difficult to be transmitted from the second exhaust scroll to the turbine housing by closing the flow rate adjusting valve. Furthermore, since the exhaust gas flows through the first exhaust scroll, it is possible to avoid the problem that exhaust gas is trapped in the exhaust turbine. For this reason, it is possible to prevent turbulence due to blowing up and prevent exhaust gas heat from being taken away by the exhaust turbine due to turbulence of the exhaust gas. Thereby, high-temperature exhaust gas can be led to the catalyst, and the warm-up time of the catalyst can be shortened.
Thus, by adopting the present invention, early activation of the catalyst can be carried out while improving fuel efficiency.

1 is a schematic view of an intake / exhaust system of an engine. It is explanatory drawing of the drive mechanism of a flow regulating valve and a wastegate valve. (A) a graph showing changes in the flow rate through the flow rate adjusting valve and the waste gate valve with respect to changes in the actuator operating angle; (b) a graph showing changes in the opening amounts of the flow rate adjusting valve and the waste gate valve with respect to changes in the actuator operating angle; (C) It is a graph which shows the target supercharging pressure with respect to an actuator operating angle. It is a flowchart which shows the example of control which performs early warming-up of a catalyst.

  EMBODIMENT OF THE INVENTION Below, the form for inventing is demonstrated in detail based on drawing.

  A specific example of an intake / exhaust device for an internal combustion engine to which the present invention is applied will be described. In addition, the Example disclosed below discloses an example and it cannot be overemphasized that this invention is not limited to an Example.

[Example 1]
A first embodiment will be described with reference to FIGS.
An engine 1 for driving a vehicle (an internal combustion engine that generates rotational power by burning fuel, regardless of the type of fuel, regardless of the engine type such as a reciprocating engine or a rotary engine) is equipped with a turbocharger 2.

The engine 1 includes an intake passage 3 that guides intake air into the engine cylinder, and an exhaust passage 4 that purifies exhaust gas generated in the cylinder and discharges the exhaust gas into the atmosphere.
The turbocharger 2 is a supercharger that pressurizes the intake air sucked into the engine 1 by the energy of the exhaust gas discharged from the engine 1. The turbocharger 2 is driven by the exhaust gas of the engine 1, and the exhaust turbine 5. And an intake air compressor 6 that pressurizes the intake air sucked into the engine 1.

  The exhaust turbine 5 includes a turbine impeller 5a that is rotationally driven by exhaust gas discharged from the engine 1, and a spiral turbine housing 5b that accommodates the turbine impeller 5a. Details of the exhaust turbine 5 will be described later.

The intake compressor 6 includes a compressor impeller 6a that is driven by the rotational force of the turbine impeller 5a to pressurize the intake air in the intake passage 3, and a spiral compressor housing that accommodates the compressor impeller 6a. The
The turbine impeller 5a and the compressor impeller 6a are coupled via a shaft 7, and the shaft 7 is supported by the center housing so as to be rotatable at high speed.

The intake passage 3 is constituted by internal passages of an intake pipe, an intake manifold, and an intake port.
Specifically, in the intake passage 3, an air cleaner 11 that removes dust and dirt contained in the intake air sucked into the engine 1, an intake air compressor 6 of the turbocharger 2, and intake air that has been compressed and heated by the intake air compressor 6. There are provided an intercooler 12 for forced cooling, a throttle valve 13 for adjusting the amount of intake air sucked into the engine 1, a supercharging pressure sensor 14 for detecting a supercharging pressure, etc. installed in a surge tank or the like.

The exhaust passage 4 is constituted by internal passages of an exhaust port, an exhaust manifold, and an exhaust pipe.
Specifically, in the exhaust passage 4, an exhaust turbine 5 of the turbocharger 2, a catalyst 15 disposed on the exhaust downstream side of the exhaust turbine 5 to purify the exhaust gas, an exhaust sound is silenced, and the exhaust gas is brought into the atmosphere. An exhaust muffler 16 and the like are provided.
The catalyst 15 is a well-known catalyst. To disclose a specific example, the catalyst 15 is a well-known three-way catalyst that adopts a monolith structure, and is a harmful substance contained in the exhaust gas when heated to an activation temperature. Is purified by oxidation and reduction.

  The turbocharger 2 is a variable capacity type, and the exhaust turbine 5 has a flow rate adjusting valve 17 that adjusts the flow rate of exhaust gas that drives the turbine impeller 5a, and the flow rate of exhaust gas that bypasses the turbine impeller 5a. A wastegate valve 18 is provided.

  Specifically, independent first and second exhaust scrolls 21 and 22 for turning the exhaust gas discharged from the engine 1 and blowing it to the turbine impeller 5a are provided inside the turbine housing 5b.

The first exhaust scroll 21 is not provided with an opening / closing means, and is always open so that the exhaust gas always passes through the first exhaust scroll 21.
Specifically, the exhaust upstream portion of the first exhaust scroll 21 is always in communication with the exhaust inlet (connection port with the exhaust manifold) of the turbine housing 5 b, and the exhaust gas always passes through the first exhaust scroll 21 and the turbine blades. It is blown out to the car 5a.

On the other hand, the second exhaust scroll 22 is provided so as to be opened and closed by the flow rate adjusting valve 17.
Specifically, the exhaust upstream portion of the second exhaust scroll 22 communicates with the exhaust gas upstream area of the first exhaust scroll 21 via a flow path switching hole 23 formed in the turbine housing 5b. The switching hole 23 is opened and closed by the flow rate adjusting valve 17.

  The flow rate adjustment valve 17 opens and closes the flow path switching hole 23 and adjusts the opening degree thereof. By adjusting the opening degree of the flow rate adjustment valve 17, the amount of exhaust gas flowing into the second exhaust scroll 22 (that is, the flow rate adjustment valve 17). The supercharging pressure is controlled by controlling the amount of exhaust gas blown from the second exhaust scroll 22 to the turbine impeller 5a.

As shown in FIG. 2, the flow rate adjusting valve 17 may open and close the downstream end of the flow path switching hole 23, but unlike FIG. 2, the upstream end of the flow path switching hole 23 is opened and closed. It is desirable to do.
Specifically, unlike FIG. 2, the flow rate adjustment valve 17 is arranged in the space of the exhaust gas diversion location of the first exhaust scroll 21 and the second exhaust scroll 22, and the flow rate adjustment valve 17 is connected to the flow path switching hole 23. It is desirable that the exhaust gas does not enter the entire range of the second exhaust scroll 22 by closing (the structure in which exhaust gas cannot be accumulated in the second exhaust scroll 22 when the flow rate adjustment valve 17 is fully closed). Is.

On the other hand, in the turbine housing 5b, there is a bypass passage 24 that guides a part of the exhaust gas flowing into the turbine housing 5b to the exhaust downstream side (exhaust upstream side of the catalyst 15) by bypassing the bypass wheel 5a. Is formed.
The bypass path 24 is opened and closed by a waste gate valve 18. The wastegate valve 18 adjusts the opening degree of the bypass passage 24. By adjusting the opening degree of the wastegate valve 18, the amount of exhaust gas that bypasses the turbine impeller 5a is controlled and the boost pressure is increased. To control.

Next, the drive mechanism of the flow rate adjusting valve 17 and the wastegate valve 18 will be described.
The flow rate adjusting valve 17 and the wastegate valve 18 are opened and closed by a single actuator 31 that is controlled by the ECU 30.

The actuator 31 drives both the flow rate adjustment valve 17 and the wastegate valve 18 via the link device 32.
Specifically, the link device 32 converts the output of the actuator 31 to drive the flow rate adjustment valve 17 and the waste gate valve 18, and opens the waste gate valve 18 in the middle of the opening degree change of the flow rate adjustment valve 17. Let Further, the link device 32 is provided with an early warm-up position θz (according to FIG. 3) that closes the flow rate adjusting valve 17 and fully opens the wastegate valve 18 (maximum opening).

  The actuator 31 generates rotation output or stroke output by energization control, and employs an electric actuator that generates rotation output as an example. A specific example of the electric actuator is a combination of an electric motor (for example, a DC motor) that generates a rotational output when energized and a speed reducer (for example, a gear speed reducer) that reduces the rotational output of the electric motor and increases output torque. It is a thing which generate | occur | produces the rotational torque according to the energization amount applied to an electric motor.

The actuator 31 may or may not include a return spring that returns the operating angle of the output shaft to the initial position θ0 (sign, see FIG. 3).
Even if a return spring is not built in the actuator 31, by providing a return spring in each of the flow rate adjustment valve 17 and the wastegate valve 18, the restoring force of each return spring is transmitted to the actuator 31 via the link device 32. Therefore, the operating angle of the actuator 31 can be returned to the initial position θ0 when the actuator 31 is stopped.
Of course, an auxiliary return spring having a small urging force may be provided on the actuator 31 to generate a force for returning the operating angle of the actuator 31 to the initial position θ0.

The actuator 31 includes an actuator position sensor 33 that detects an output displacement.
A specific example of the actuator position sensor 33 is a rotation angle sensor that detects the operating angle of the actuator 31 (the rotation angle of the output shaft). The rotation angle sensor may be a non-contact type using a magnetic sensor or the like, or a contact type using a potentiometer or the like. The sensor output of the actuator position sensor 33 is output to the ECU 30 that controls the opening of the flow rate adjusting valve 17 and the wastegate valve 18 by energizing the actuator 31.

  An example of the operation characteristic of the flow rate adjusting valve 17 by the link device 32 is shown by a solid line A1 in FIG. Specifically, the link device 32 (i) increases the opening of the flow rate adjustment valve 17 as the operating angle of the actuator 31 (specifically, the displacement angle of the output shaft) moves from the initial position θ0 toward the first operating angle θ1. Gradually increase from the fully closed state toward the fully open direction, (ii) keep the opening of the flow rate adjustment valve 17 in the fully open state in the range of the first operating angle θ1 to the second operating angle θ2, and (iii) second operation The flow rate adjustment valve 17 is gradually reduced from the fully open state toward the fully closed direction toward the early warm-up position θz (an operation angle larger than the second operation angle θ2: for example, the maximum output angle of the actuator 31) from the angle θ2. Yes, at the early warm-up position θz, the flow rate adjustment valve 17 is set to a fully closed state.

  As the opening degree of the flow rate adjustment valve 17 changes as described above with respect to the operating angle of the actuator 31, the flow rate of the exhaust gas passing through the flow rate adjustment valve 17 (that is, the exhaust flow rate passing through the second exhaust scroll 22) is increased. As shown by the solid line A2 in FIG. 3A, (i) the exhaust flow rate gradually increases from 0 (zero) as the operating angle of the actuator 31 moves from the initial position θ0 toward the first operating angle θ1, and (ii) ) The exhaust flow rate is kept at the maximum in the range from the first operating angle θ1 to the second operating angle θ2, and (iii) the exhaust flow rate gradually decreases from the maximum as it goes from the second operating angle θ2 toward the early warm-up position θz. The exhaust flow rate becomes 0 (zero) at the early warm-up position θz.

  An example of the operation characteristic of the wastegate valve 18 by the link device 32 is shown by a broken line B1 in FIG. Specifically, the link device 32 sets the waste gate valve 18 to a fully closed state in the range (i) the operating angle of the actuator 31 is from the initial position θ0 to the first operating angle θ1, and (ii) the first operating angle θ1. The opening of the waste gate valve 18 gradually increases from the fully closed state toward the fully open direction as it goes from the second operating angle θ2 toward the second operating angle θ2, and (iii) the wastegate in the range from the second operating angle θ2 to the early warm-up position θz. The opening degree of the valve 18 is maintained in a fully opened state, and the wastegate valve 18 is set in a fully opened state in the early warm-up position θz.

  As the opening degree of the wastegate valve 18 changes as described above with respect to the operating angle of the actuator 31, the flow rate of exhaust gas passing through the wastegate valve 18 (that is, exhaust flow rate passing through the bypass path 24) is As indicated by the broken line B2 in FIG. 3 (a), (i) the exhaust gas flow rate is maintained at 0 (zero) in the range of the operating angle of the actuator 31 from the initial position θ0 to the first operating angle θ1, and (ii) the first operation The exhaust flow rate gradually increases from the angle θ1 toward the second operating angle θ2, and (iii) the exhaust flow rate increases gradually from the second operating angle θ2 toward the early warm-up position θz, The exhaust flow rate becomes maximum at the early warm-up position θz.

  By providing the link device 32 in this manner, the supercharging pressure by the turbocharger 2 can be arbitrarily controlled by changing the operating angle of the actuator 31. Specifically, as shown by a solid line C in FIG. 3C, (i) the boost pressure is gradually decreased as the operating angle of the actuator 31 is changed from the initial position θ0 to the second operating angle θ2. (Ii) In the range from the second operating angle θ2 to the early warm-up position θz, there is a supercharging pressure dead zone where the supercharging pressure does not change.

  The specific structure of the link device 32 is not limited. For example, the cam link mechanism using a cam groove, the opening amount of the wastegate valve 18 is controlled by the play amount provided on the wire, and the pulley diameter is driven. A wire mechanism that adjusts torque, a transmission mechanism that controls a valve opening start position of the wastegate valve 18 by combining a lock mechanism using a spring force and a release mechanism can be applied in various ways.

  The actuator 31 and the link device 32 are attached to the side of the intake compressor 6 that is not easily affected by the heat of the exhaust gas (which is an example and not limited), and as shown in FIG. 2, from the link device 32 to the flow rate adjustment valve 17. The output is transmitted through the first rod 34, and the output is transmitted from the link device 32 to the waste gate valve 18 through the second rod 35.

  The specific structures of the flow rate adjusting valve 17 and the waste gate valve 18 are not limited, but as an example, a hinge valve structure in which the valve body is rotated as shown in FIG. 2 is adopted.

  Specifically, the flow rate adjusting valve 17 couples the valve body that directly opens and closes the flow path switching hole 23, a rotating shaft that is rotatably supported by the turbine housing 5b, and the rotating shaft and the valve body. An internal arm and an external arm that is disposed outside the turbine housing 5b and connects the rotating shaft and the end of the first rod 34 are provided, and the flow rate adjusting valve 17 is opened and closed by the stroke displacement of the first rod 34. Operated.

  The wastegate valve 18 has the same structure as the flow rate adjustment valve 17 described above, a valve body that directly opens and closes the bypass path 24, a rotating shaft that is rotatably supported by the turbine housing 5b, An internal arm that couples the pivot shaft and the valve body, and an external arm that is disposed outside the turbine housing 5b and connects the pivot shaft and the end of the second rod 35 are provided. The waste gate valve 18 is opened and closed by the stroke displacement.

As described above, the intake / exhaust device for an internal combustion engine of this embodiment employs a structure in which the exhaust turbine 5 of the turbocharger 2 is disposed on the exhaust upstream side of the catalyst 15 that purifies the exhaust gas.
In addition, as described above, the exhaust turbine 5 of this embodiment is
A turbine impeller 5a that is rotationally driven by exhaust gas;
A turbine housing 5b having independent first and second exhaust scrolls 21 and 22 for swirling exhaust gas exhausted and blowing the exhaust gas to the turbine impeller 5a;
A flow rate adjusting valve 17 for opening and closing the second exhaust scroll 22;
A wastegate valve 18 that opens and closes a bypass path 24 that guides exhaust gas upstream of the turbine impeller 5a to the exhaust upstream side of the catalyst 15 by bypassing the turbine impeller 5a;
Is provided.
The turbocharger 2 is provided in a state where the first exhaust scroll 21 is always opened, and adopts a configuration in which the actuator 31 is energized and controlled by the ECU 30 (corresponding to a control device).

The ECU 30 is provided with a supercharging pressure control means (control program) that controls the supercharging pressure of the turbocharger 2 by controlling the energization of the actuator 31.
Specifically, the ECU 30 is an engine control unit in which a microcomputer is mounted, and the supercharging pressure control means is an operating state of the engine 1 (an engine speed detected by an engine speed sensor 36 provided in the engine 1). And the target boost pressure suitable for the operating state of the engine 1 is calculated from the throttle valve 13 opening degree and the like. Then, pressure feedback control is performed on the actuator 31 so that the actual boost pressure (intake pressure) detected by the boost pressure sensor 14 matches the target boost pressure (this is an example and is not limited).

On the other hand, when the ECU 30 is in an operating state where early warm-up of the catalyst 15 is desired, such as immediately after a cold start, that is, when the actual temperature or predicted temperature of the catalyst 15 has not reached the activation temperature, Prior to the operation of the control means, a catalyst warm-up means (control program) is provided for performing early warm-up of the catalyst 15.
The catalyst warm-up means closes the second exhaust scroll 22 by the flow rate adjustment valve 17 and opens the bypass path 24 by the waste gate valve 18 when the catalyst 15 is warmed up early. Specifically, when the catalyst 15 is warmed up early, the flow rate adjustment valve 17 is fully closed and the wastegate valve 18 is fully opened.

This will be specifically described.
As described above, the turbocharger 2 of this embodiment is configured to open and close the flow rate adjusting valve 17 and the wastegate valve 18 by one actuator 31 that is controlled by the ECU 30.
That is, the ECU 30 controls the opening and closing of the flow rate adjustment valve 17 and the wastegate valve 18 via the link device 32 by controlling the energization of the actuator 31. When the catalyst 15 is warmed up early, the flow rate is controlled. The second exhaust scroll 22 is closed by the adjusting valve 17, and the bypass passage 24 is opened by the waste gate valve 18.

More specifically, as described above, the link device 32 converts the output of the actuator 31 to drive both the flow rate adjustment valve 17 and the waste gate valve 18. An early warm-up position θz is provided in which the wastegate valve 18 is fully opened while the adjustment valve 17 is closed.
When the ECU 30 warms up the catalyst 15 early, the actuator 31 sets the link device 32 to the early warm-up position θz, and closes the flow rate adjustment valve 17 while fully opening the wastegate valve 18. It is provided as follows.

  Of course, the ECU 30 is provided to start supercharging pressure control by the turbocharger 2 by the above-described supercharging pressure control means when the early warm-up of the catalyst 15 is completed.

A control example of the early warm-up of the catalyst 15 will be described based on the flowchart of FIG.
Step S1: When this control routine is entered (start), first, it is determined whether or not the operating state is desired for early warm-up of the catalyst 15. Specifically, the ECU 30 determines that early warm-up of the catalyst 15 is desired when the actual temperature or the predicted temperature of the catalyst 15 has not reached the activation temperature, such as immediately after a cold start. If the determination result is NO (when early warm-up of the catalyst 15 is not desired), this control routine is ended (END).

  Step S2: If the determination result in Step S1 is YES, the actuator 31 is energized and the link device 32 is set to the early warm-up position θz. As a result, the flow rate adjusting valve 17 closes the flow path switching hole 23 and sets the second exhaust scroll 22 to be fully closed, the wastegate valve 18 fully opens the bypass path 24, and the exhaust gas flows into the first exhaust scroll 21. It flows in both bypass paths 24.

Step S3: It is determined whether or not the early warm-up of the catalyst 15 has been completed. Specifically, it is determined whether the actual temperature or the predicted temperature of the catalyst 15 has reached the activation temperature. If the determination result in step S3 is NO, the early warm-up of the catalyst 15 is continued. If the determination result in step S3 is YES, the early warm-up of the catalyst 15 is terminated, and this control routine is terminated (END).
That is, if the determination result in step S3 is YES, the early warm-up of the catalyst 15 is terminated and supercharging pressure control is started.

(Effect 1 of Example 1)
In the first embodiment, when the catalyst 15 is warmed up early, the flow rate adjusting valve 17 is fully closed and the wastegate valve 18 is fully opened, and exhaust gas is supplied to both the first exhaust scroll 21 and the bypass passage 24. To flow. As a result, it is possible to avoid the problem that the bypass path 24 acts as a bottleneck during the early warm-up of the catalyst 15 and to prevent the exhaust pressure on the upstream side of the exhaust turbine 5 from rising. For this reason, the pumping loss of the engine 1 can be suppressed and the fuel consumption of the vehicle can be improved.

(Effect 2 of Example 1)
In the first embodiment, when the catalyst 15 is warmed up early, the flow rate adjusting valve 17 is fully closed to prevent the heat of the exhaust gas from being transmitted from the second exhaust scroll 22 to the turbine housing 5b. it can. Further, when the catalyst 15 is warmed up early, the exhaust gas is caused to flow through the first exhaust scroll 21, so that it is possible to prevent the exhaust gas from being accumulated in the turbine housing 5 b. As a result, it is possible to prevent the disturbance of the exhaust gas flow caused by the puddle, and to prevent the exhaust turbine 5 from taking heat of the exhaust gas due to the disturbance of the exhaust gas flow.
As a result, it is possible to suppress the exhaust gas heat from being taken away by the exhaust turbine 5 as much as possible, and an effect of guiding the high-temperature exhaust gas to the catalyst 15 can be obtained. Therefore, the warm-up time of the catalyst 15 can be shortened.

  In this way, the intake / exhaust device for an internal combustion engine of this embodiment that employs the present invention can implement early activation of the catalyst 15 while improving fuel efficiency.

  In the above embodiment, the “supercharging pressure control means” is activated when early warm-up of the catalyst 15 is desired, such as immediately after a cold start (when the actual temperature or predicted temperature of the catalyst 15 does not reach the activation temperature). In the above example, the “catalyst warming means” is operated in preference to the above. However, when the vehicle operating state prioritizes the increase in engine output (eg, increase in accelerator opening), The “supercharging pressure control means” may be provided with priority.

  In the above-described embodiment, an example in which an electric actuator using an electric motor as a drive source is used as an example of the actuator 31 is shown. However, any type of actuator 31 that can be energized and controlled by the ECU 30 (negative pressure actuator, hydraulic actuator, etc.) ).

  In the above embodiment, an example in which both the flow rate adjustment valve 17 and the waste gate valve 18 are driven to open and close by one actuator 31 is shown. However, the link device 32 is abolished and the flow rate adjustment valve 17 and the waste gate valve 18 are connected. A dedicated actuator may be used for each.

  In the above embodiment, an example in which the wastegate valve 18 is fully opened when the catalyst 15 is warmed up early is shown, but the present invention is not limited thereto. Specifically, when the catalyst 15 is warmed up early, it is preferable to set the opening of the waste gate valve 18 to be fully open or close to full open, and is not limited to full open. More specifically, when the catalyst 15 is warmed up early, it is most preferable that the wastegate valve 18 is fully open, and then the opening of the wastegate valve 18 is fully open (maximum opening). When it is 100%, it is preferably 90% or more, and may be 80% or more.

  In the above embodiment, the example in which the actuator 31 is controlled by pressure feedback has been described. However, the actuator 31 may be controlled by feedback of the mechanical output value of the actuator 31. As a specific example, the target operating angle of the actuator 31 is calculated from the target boost pressure, and the ECU 30 feedback-controls the actuator 31 so that the actual operating angle detected by the actuator position sensor 33 matches the target operating angle. May be.

  In the above embodiment, the example in which the actuator 31 is feedback-controlled has been shown, but the actuator 31 may be feedforward controlled (open control). As a specific example, the target operating angle of the actuator 31 is calculated from the target boost pressure, the target energization amount corresponding to the target operating angle is calculated, and the electric power corresponding to the target energization amount is applied to the electric motor. good.

2 ... Turbocharger 5 ... Exhaust turbine 5a ... Turbine impeller 5b ... Turbine housing 15 ... Catalyst
DESCRIPTION OF SYMBOLS 17 ... Flow control valve 18 ... Wastegate valve 21 ... 1st exhaust scroll 22 ... 2nd exhaust scroll 24 ... Bypass path 30 ... ECU (control apparatus)

Claims (4)

In an intake / exhaust device for an internal combustion engine in which an exhaust turbine 5 of a turbocharger (2) is disposed upstream of an exhaust gas of a catalyst (15) for purifying exhaust gas,
The exhaust turbine (5) includes a turbine impeller (5a) that is rotationally driven by exhaust gas, and independent first and second exhaust scrolls that swirl the exhaust gas that is exhausted and spray it onto the turbine impeller (5a). A turbine housing (5b) having (21, 22), a flow rate adjusting valve (17) for opening and closing the second exhaust scroll (22), and exhaust gas on the exhaust upstream side of the turbine impeller (5a), A wastegate valve (18) that opens and closes a bypass passage (24) that bypasses the turbine impeller (5a) and leads to the exhaust upstream side of the catalyst (15), and the first exhaust scroll (21) Is always open,
The control device (30) that performs opening / closing control of the flow rate adjusting valve (17) and the waste gate valve (18) causes the flow rate adjusting valve (17) to perform the warming-up of the catalyst (15). An intake / exhaust device for an internal combustion engine, wherein the second exhaust scroll (22) is closed and the bypass gate (24) is opened by the waste gate valve (18). The intake / exhaust device for an internal combustion engine according to claim 1,
The turbocharger (2) is configured to open and close the flow rate adjusting valve (17) and the wastegate valve (18) by one actuator (31) whose operation is controlled by the control device (30). Intake / exhaust device for internal combustion engine. The intake / exhaust device for an internal combustion engine according to claim 2,
The turbocharger (2) includes a link device (32) that converts the output of the actuator (31) to drive both the flow rate adjusting valve (17) and the wastegate valve (18).
The link device (32) is provided with an early warm-up position (θz) in which the wastegate valve (18) is fully opened while the flow rate adjusting valve (17) is closed. Intake and exhaust equipment. The intake / exhaust device for an internal combustion engine according to any one of claims 1 to 3,
The controller (30) fully closes the flow rate adjustment valve (17) and fully opens the waste gate valve (18) when the catalyst (15) is warmed up early. An intake / exhaust device for an internal combustion engine.

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