JP2010190049A - Control device for internal combustion engine with superchargers - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly raise the temperature of a catalyst in a twin turbo-system. <P>SOLUTION: This control device for an internal combustion engine with superchargers operates a second supercharger by regulating a supercharging pressure using an exhaust gas changeover valve when the temperature of the catalyst is equal to or less than a predetermined one in an operating range in which only a first supercharger is to be operated and the supercharging pressure must be regulated using an exhaust gas bypass valve, and supplies a supercharging air by the operation of the second supercharger to the upstream side of the compressor of the first supercharger. The intake air heated by the operation of the second supercharger is supplied to the upstream side of the compressor of the first supercharger by operating the second supercharger using the exhaust energy which is disposed off by a Waste gate. Consequently, the temperature of the exhaust gas can be raised by raising the temperature of the intake air, and the temperature of the catalyst can be raised. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger having a plurality of superchargers.

  Conventionally, control for appropriately warming up the catalyst provided on the exhaust passage has been proposed. For example, Patent Document 1 proposes that the bypass valve is controlled to open so that the intake air bypasses the intercooler from the start to the completion of catalyst warm-up.

  In addition, Patent Documents 2 and 3 describe techniques related to the present invention. Patent Document 2 proposes that an electric compressor is provided upstream of the compressor of the turbocharger, and the intake air is increased by circulating the intake air upstream of the electric compressor. Patent Document 3 proposes that in the twin turbo system, the supercharging pressure and the catalyst recovery are appropriately performed by controlling the supercharger bypass amount at the time of catalyst reduction / regeneration.

JP 2005-351184 A JP 2006-183643 A JP 2008-2319 A

  By the way, in the twin turbo system in which two turbochargers are arranged in the intake passage and the exhaust passage, since the two turbocharger turbines are arranged upstream of the catalyst, the catalyst temperature tends to decrease. It is in. Patent Documents 1 to 3 described above do not describe a method for appropriately suppressing a decrease in catalyst temperature in such a twin interbo system.

  The present invention has been made to solve the above-described problems, and provides a control device for an internal combustion engine with a supercharger capable of appropriately raising the catalyst temperature in a twin turbo system. Objective.

  In one aspect of the present invention, a control device for an internal combustion engine with a supercharger having a first supercharger and a second supercharger adjusts an exhaust flow rate to the turbine of the second supercharger. An exhaust gas switching valve, an exhaust gas bypass valve provided on a passage that bypasses the turbine of the first supercharger, an operating region in which only the first supercharger should be operated, and the exhaust gas bypass valve In the operation region where the supercharging pressure is to be adjusted using the above, when the catalyst temperature is equal to or lower than the predetermined temperature, the supercharging pressure is adjusted using the exhaust switching valve instead of the exhaust bypass valve. Control means for operating the second supercharger and performing control for supplying supercharged air from the operation of the second supercharger to the upstream side of the compressor of the first supercharger. .

  The control device for an internal combustion engine with a supercharger has a first supercharger and a second supercharger, and uses the exhaust gas switching valve and the exhaust bypass valve to provide the first and second superchargers. Change the mode to activate the to supercharge. The control means is an operating region in which only the first supercharger is to be operated and an operating region in which the supercharging pressure is to be adjusted using the exhaust bypass valve, and the catalyst temperature is equal to or lower than a predetermined temperature. In addition, the second supercharger is operated by adjusting the supercharging pressure using the exhaust gas switching valve, and the supercharged air generated by the operation of the second supercharger is supplied to the compressor of the first supercharger. Supply upstream. Thereby, the second supercharger can be operated using the exhaust energy discarded by the wastegate for adjusting the supercharging pressure when only the first supercharger is operated. In addition, the intake air that has been compressed by the compressor and becomes high temperature by the operation of the second supercharger can be supplied to the upstream side of the compressor of the first supercharger. That is, the intake air that has reached a high temperature can be drawn from the inlet of the compressor of the first supercharger.

  Therefore, according to the above control device for an internal combustion engine with a supercharger, the intake air temperature of the internal combustion engine can be raised, and the exhaust gas temperature can be raised. Therefore, it is possible to appropriately increase the catalyst inlet temperature.

1 is a schematic configuration diagram of a vehicle to which a control device for an internal combustion engine with a supercharger according to an embodiment is applied. It is a figure for demonstrating the driving | operation area | region used when switching the mode which operates two turbochargers. It is a flowchart which shows the control processing in this embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[Device configuration]
FIG. 1 is a schematic view showing a configuration of a vehicle to which a control device for an internal combustion engine with a supercharger according to this embodiment is applied. In FIG. 1, solid line arrows indicate an example of gas flow, and broken line arrows indicate signal input and output.

  The vehicle mainly includes an intake passage 3, turbochargers 4, 5, an intake switching valve 6, a first intake bypass valve 7, a second intake bypass valve 8, an exhaust passage 10, and an exhaust bypass passage. 10c, an exhaust gas switching valve 11, an exhaust gas bypass valve 12, a catalyst 13, and an ECU (Engine Control Unit) 50.

  Intake air (air) purified by an air cleaner (not shown) is introduced into the intake passage 3. The intake passage 3 is branched into intake passages 3a and 3b on the way. A compressor 4a of the turbocharger 4 is disposed in the intake passage 3a, and a compressor 5a of the turbocharger 5 is disposed in the intake passage 3b. The compressors 4a and 5a compress the intake air that passes through the intake passages 3a and 3b, respectively.

  An intake switching valve 6 is provided in the intake passage 3b. The intake switching valve 6 is controlled in opening degree by a control signal S6 supplied from the ECU 50 via an actuator (not shown) to adjust the flow rate of the intake air passing through the intake passage 3b.

  In addition, intake bypass passages 3c and 3d are connected to the intake passage 3b on the downstream side of the compressor 5a of the turbocharger 5. The intake bypass passage 3c is connected to the intake passage 3b upstream of the compressor 5a of the turbocharger 5 and the intake passage 3b downstream of the compressor 5a of the turbocharger 5, and the intake bypass passage 3d is The turbocharger 4 is connected to the intake passage 3a on the upstream side of the compressor 4a and the intake passage 3b on the downstream side of the compressor 5a of the turbocharger 5. That is, the intake bypass passage 3c connects the inlet of the compressor 5a of the turbocharger 5 and the outlet of the compressor 5a, and the intake bypass passage 3d connects the inlet of the compressor 4a of the turbocharger 4 to the turbocharger. The outlet of the compressor 5a of the feeder 5 is connected.

  Further, a first intake bypass valve 7 is provided on the intake bypass passage 3c, and a second intake bypass valve 8 is provided on the intake bypass passage 3d. The first intake bypass valve 7 and the second intake bypass valve 8 are controlled in opening degree by control signals S7 and S8 supplied from the ECU 50 via actuators (not shown), respectively, and the intake bypass passages 3c and 3d. Adjust the flow rate of the intake air passing through. When the intake bypass passages 3c and 3d and the first intake bypass valve 7 and the second intake bypass valve 8 are used, the turbocharger 5 is supercharged when the turbocharger 4 is operated. It is possible to control whether the intake air is supplied to the compressor 4a of the turbocharger 4 or the compressor 5a of the turbocharger 5.

  The intake air that has passed through the intake passage 3 as described above passes through the intercooler, then passes through the intake manifold (intake manifold), and is supplied to the engine (internal combustion engine) (not shown). The engine generates power by burning a mixture of intake air and fuel. Exhaust gas generated by combustion in the engine is discharged to the exhaust passage 10.

  The exhaust passage 10 is branched into exhaust passages 10a and 10b, and the turbine 4b of the turbocharger 4 is disposed in the exhaust passage 10a. The turbine 5b of the turbocharger 5 is disposed in the exhaust passage 10b. Is arranged. Further, a catalyst 13 configured to purify exhaust gas is provided on the exhaust passage 10 on the downstream side of the turbines 4b and 5b.

  The turbines 4b and 5b are rotated by exhaust gas passing through the exhaust passages 10a and 10b, respectively. The rotational torque of the turbines 4b and 5b is transmitted to the compressor 4a in the turbocharger 4 and the compressor 5a in the turbocharger 5 to rotate, whereby the intake air is compressed (that is, supercharged). The Rukoto.

  The turbocharger 4 is configured as a low-capacity low-speed supercharger with a large supercharging capacity in the low and medium speed range, and the turbocharger 5 is a large-capacity high speed with a large supercharging capacity in the medium and high speed range It is configured as a type supercharger. That is, the turbocharger 4 corresponds to a so-called primary turbocharger, and the turbocharger 5 corresponds to a so-called secondary turbocharger. The turbocharger 4 corresponds to the first supercharger in the present invention, and the turbocharger 5 corresponds to the second supercharger in the present invention. Thus, FIG. 1 shows an example in which a control device for an internal combustion engine with a supercharger is applied to a parallel twin turbo system (parallel sequential turbo system).

  An exhaust switching valve 11 is provided in the exhaust passage 10b. The exhaust switching valve 11 is controlled in opening degree by a control signal S11 supplied from the ECU 50 via an actuator (not shown), and adjusts the flow rate of the exhaust gas passing through the exhaust passage 10b. In other words, the exhaust gas flow rate to the turbine 5b of the turbocharger 5 is adjusted.

  The exhaust bypass passage 10c is configured to be able to flow exhaust gas by bypassing the turbine 4b of the turbocharger 4, and an exhaust bypass valve 12 is provided on the passage. The exhaust bypass valve 12 is controlled in opening degree by a control signal S12 supplied from the ECU 50 via an actuator (not shown). The exhaust bypass valve 12 corresponds to a so-called waste gate valve.

  The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). ECU50 controls each component in a vehicle based on the output of various sensors. For example, the ECU 50 operates the turbochargers 4 and 5 by controlling the intake switching valve 6, the first intake bypass valve 7, the second intake bypass valve 8, the exhaust switching valve 11, and the exhaust bypass valve 12. Performs control to switch modes. The ECU 50 corresponds to the control means in the present invention.

  Here, with reference to FIG. 2, an example of the operation region used when switching the mode for operating the turbochargers 4 and 5 will be briefly described.

  In FIG. 2, the horizontal axis indicates the engine speed, and the vertical axis indicates the engine torque (corresponding to a load). The region R1 corresponds to a region where only the turbocharger 4 is operated. Hereinafter, the region R1 is referred to as a “single turbo region”. The region R2 is basically a region where only the turbocharger 4 is operated, and corresponds to a region where the supercharging pressure is adjusted by the exhaust bypass valve 12. Hereinafter, the region R2 is referred to as a “supercharging pressure adjustment region”. The region R3 corresponds to a region where both the turbocharger 4 and the turbocharger 5 are operated. Hereinafter, the region R3 is referred to as a “two turbo region”.

The ECU 50 basically switches the mode for operating the turbocharger 4 and the turbocharger 5 based on such an operation region (regions R1 to R3).
[Control method]
Next, a control method performed by the ECU 50 in the present embodiment will be described. In the present embodiment, the ECU 50 performs control for increasing the inlet temperature of the catalyst 13 during a cold time such as after starting. Specifically, the ECU 50 increases the inlet temperature of the catalyst 13 by performing control for increasing the intake air temperature of the engine and increasing the exhaust gas temperature.

  The reason for performing such control is as follows. In the parallel twin turbo system, exhaust heat warms the turbine and various valves and pipes when it is cold immediately after start-up, and the catalyst inlet temperature does not rise and the catalyst performance does not work properly. There is a case. This is because in the parallel twin turbo system, two turbocharger turbines and a plurality of valves are arranged on the exhaust passage (specifically, on the exhaust passage upstream of the catalyst), so the heat capacity increases. This is because exhaust heat is deprived and the exhaust gas temperature is difficult to rise.

  Therefore, in this embodiment, control for suppressing such a decrease in the inlet temperature of the catalyst 13 is performed. Specifically, the ECU 50 is in a region where it cannot operate with the two turbochargers 4 and 5 in a cold state such as after starting, and in a region where the turbocharger 4 needs to be adjusted for supercharging pressure. While operating (that is, when the operation region is in the supercharging pressure adjustment region R2 (see FIG. 2)), the supercharging pressure adjustment is performed using the exhaust gas switching valve 11 instead of the exhaust bypass valve 12, Control is performed to close the first intake bypass valve 7 and open the second intake bypass valve 8.

  Thus, by adjusting the supercharging pressure using the exhaust gas switching valve 11, when the exhaust bypass valve 12 is used, the exhaust gas flowing through the turbine 4b of the turbocharger 4 (that is, discarded) The exhaust gas that has been provided can be supplied to the turbine 5 b of the turbocharger 5. That is, the turbocharger 5 can be operated by using the exhaust energy discarded by the wastegate for adjusting the supercharging pressure when only the turbocharger 4 is operated.

  Further, when the turbocharger 5 is operated in this way, the first intake bypass valve 7 is closed and the second intake bypass valve 8 is opened, whereby the turbocharger 5 is operated to operate the compressor. The intake air that has been compressed by 5a and has reached a high temperature can be supplied to the upstream side of the compressor 4a of the turbocharger 4 through the intake bypass passage 3d in which the second intake bypass valve 8 is provided. That is, the intake air that has reached a high temperature can be sucked from the inlet of the compressor 4 a of the turbocharger 4.

  As described above, according to the present embodiment, the intake air temperature of the engine can be increased, and the exhaust gas temperature can be increased. Therefore, it is possible to appropriately increase the catalyst inlet temperature.

  Next, with reference to FIG. 3, the control process in this embodiment is demonstrated concretely. FIG. 3 is a flowchart showing the control processing in the present embodiment. This process is repeatedly executed by the ECU 50.

  First, in step S101, the ECU 50 determines whether or not the operating region is in the single turbo region R1 (see FIG. 2) based on the engine speed and the engine torque. If the operating region is in the single turbo region R1 (step S101; Yes), the process proceeds to step S102. If the operating region is not in the single turbo region R1 (step S101; No), the process ends.

  In step S102, the ECU 50 performs control so that only the turbocharger 4 is operated. Specifically, the ECU 50 performs control to close the intake switching valve 6, the second intake bypass valve 8, the exhaust switching valve 11, and the exhaust bypass valve 12, and open the first intake bypass valve 7. Then, the process proceeds to step S103.

  In step S103, the ECU 50 determines whether or not the supercharging pressure needs to be adjusted. That is, the ECU 50 determines whether or not the operation region is in the supercharging pressure adjustment region R2 (see FIG. 2). If adjustment of the supercharging pressure is necessary (step S103; Yes), the process proceeds to step S104. If adjustment of the supercharging pressure is not necessary (step S103; No), the process ends.

  In step S104, the ECU 50 acquires the temperature (water temperature) of the engine coolant and determines whether or not the water temperature is equal to or lower than a predetermined temperature. Here, the ECU 50 determines, based on the water temperature, whether or not it is cold, that is, whether or not the catalyst 13 is not warmed up. If the water temperature is equal to or lower than the predetermined temperature (step S104; Yes), the process proceeds to step S105. If the water temperature is higher than the predetermined temperature (step S104; No), the process proceeds to step S108. Instead of determining whether the water temperature is equal to or lower than the predetermined temperature, it may be determined whether the catalyst temperature is equal to or lower than the predetermined temperature.

  The processes after step S105 will be described. In step S105, the ECU 50 sets the mode for rapidly warming up the catalyst 13 (catalyst rapid warm-up mode) because the water temperature is equal to or lower than the predetermined temperature. Then, the process proceeds to step S106.

  In step S <b> 106, the ECU 50 adjusts the supercharging pressure with the exhaust gas switching valve 11. That is, the ECU 50 controls the exhaust gas switching valve 11 to operate the turbocharger 5 using the exhaust energy discarded by the wastegate for adjusting the supercharging pressure when only the turbocharger 4 is operated. Adjust the supply pressure. Then, the process proceeds to step S107.

  In step S107, the ECU 50 performs control to open the exhaust gas switching valve 11, close the first intake bypass valve 7, and open the second intake bypass valve 8. That is, the ECU 50 compresses the intake air that has been compressed by the compressor 5a due to the operation of the turbocharger 5 to a high temperature, through the intake bypass passage 3d provided with the second intake bypass valve 8, and the compressor 4a of the turbocharger 4. Control to supply to the upstream side. Then, the process ends.

  Next, the process after step S108 is demonstrated. In step S108, the ECU 50 adjusts the supercharging pressure with the exhaust bypass valve 12. In this case, since the water temperature is higher than the predetermined temperature, it can be said that the catalyst 13 does not need to be warmed up. Therefore, the ECU 50 adjusts the supercharging pressure by the exhaust bypass valve 12 unlike the process of step S105 described above. . Then, the process proceeds to step S109. In step S109, the ECU 50 closes the exhaust bypass valve 12. Then, the process proceeds to step S110.

  In step S110, the ECU 50 determines whether or not it is a mode (advancing mode) in which the turbocharger 5 should be operated by being run up. That is, it is determined whether or not the mode should be switched from the mode in which only the turbocharger 4 is operated to the mode in which both the turbochargers 4 and 5 are operated. When it is a run-up mode (Step S110; Yes), processing progresses to Step S111. In this case, the ECU 50 opens the exhaust gas switching valve 11 (step S111), and the process ends. On the other hand, if the run mode is not set (step S110; No), the process ends.

According to the control process in the present embodiment described above, the catalyst inlet temperature can be appropriately increased.
[Modification]
The present invention is not limited to the application to the parallel twin turbo system, but can be similarly applied to a system in which two turbochargers are arranged in series in the intake passage and the exhaust passage (series twin turbo system). it can.

3 Intake passage 4, 5 Turbocharger 4a, 5a Compressor 4b, 5b Turbine 6 Intake switching valve 7 First intake bypass valve 8 Second intake bypass valve 10 Exhaust passage 10c Exhaust bypass passage 11 Exhaust switch valve 12 Exhaust bypass valve 13 Catalyst 50 ECU

Claims (1)

A control device for an internal combustion engine with a supercharger having a first supercharger and a second supercharger,
An exhaust gas switching valve for adjusting an exhaust gas flow rate to the turbine of the second supercharger;
An exhaust bypass valve provided on a passage that bypasses the turbine of the first supercharger;
In the operation region where only the first supercharger is to be operated, and in the operation region where the supercharging pressure is to be adjusted using the exhaust bypass valve, when the catalyst temperature is equal to or lower than a predetermined temperature, The second supercharger is operated by adjusting the supercharging pressure using the exhaust gas switching valve instead of the exhaust bypass valve, and the supercharged air generated by the operation of the second supercharger is And a control unit for controlling the supply of the turbocharger to the upstream side of the compressor of the supercharger.

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