JP2010151085A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of resolving at an early stage the freezing of each control valve in a twin turbo system. <P>SOLUTION: The control device of the internal combustion engine has first and second superchargers. The bypass path connects between the downstream side of the compressor of the second supercharger and the upstream side of the compressor of the first supercharger. An air intake control valve, an exhaust gas control valve and a bypass valve are disposed on an air intake path, a path of an exhaust gas and the bypass, respectively. A freezing estimation means estimates the freezing between the exhaust gas control valve, air intake valve and bypass valve at the starting of the internal combustion engine. A valve control means controls the exhaust gas control valve to be opened to a predetermined open degree so that the exhaust gas is supplied to the turbine of the second supercharger, when freezing occurs in the intake control valve and the bypass valve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including two superchargers arranged in an intake passage and an exhaust passage.

  2. Description of the Related Art Conventionally, a technique for determining icing of a switching valve (control valve) provided in an exhaust passage or the like in a control device for an internal combustion engine provided with a supercharger has been proposed. For example, in Patent Document 1, if the exhaust control valve of the supercharger is not in a normal opening at the start and is in a temperature range where freezing can occur, it is determined that freezing occurs, and after a predetermined period has elapsed. A technique for canceling freezing determination is described. In addition, Patent Document 2 describes a technique related to the present invention.

JP 2008-106725 A Japanese Patent Laid-Open No. 2001-23496

  When the switching valve is frozen, travel of the vehicle is restricted. Therefore, when icing occurs in the switching valve, the control device for the internal combustion engine needs to release the icing state at an early stage. However, Patent Literature 1 and Patent Literature 2 only disclose the method for determining the icing of the switching valve, and do not disclose a method for quickly releasing the icing state.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can quickly eliminate icing of each control valve in a twin turbo system. To do.

  According to one aspect of the present invention, there is provided a control device for an internal combustion engine including a first supercharger and a second supercharger, the turbine of the first supercharger and the second supercharger. An exhaust passage communicating with the turbine of the compressor, an intake passage communicating with the compressor of the first supercharger and the compressor of the second supercharger, and a downstream side of the compressor of the second supercharger And a bypass passage that bypasses the upstream side of the compressor of the first supercharger, an exhaust control valve that is provided on the exhaust passage and controls an exhaust passage, and is provided on the intake passage. An intake control valve that controls the flow path of the engine, a bypass valve that is provided on the bypass passage and controls the opening and closing of the bypass passage, the exhaust control valve, the intake control valve when the internal combustion engine is started, Freezing estimation hand to estimate freezing with bypass valve And a valve control means for performing opening control of the exhaust control valve by a predetermined opening so that exhaust is supplied to the turbine of the second supercharger when icing occurs in the intake control valve and the bypass valve. And comprising.

  The control device for an internal combustion engine is applied to a twin turbo system having a first supercharger and a second supercharger. The bypass passage bypasses the downstream side of the compressor of the second supercharger and the upstream side of the compressor of the first supercharger. An intake control valve, an exhaust control valve, and a bypass valve are disposed on the intake passage, the exhaust passage, and the bypass passage, respectively. The icing estimation means and the valve control means are, for example, an ECU (Electronic Control Unit). The icing estimation means estimates icing of the exhaust control valve, the intake control valve, and the bypass valve when starting the internal combustion engine based on, for example, the outside air temperature, the temperature of the cooling water, the temperature on the intake passage, and the like. When icing occurs in the intake control valve and the bypass valve, the valve control means opens the exhaust control valve by a predetermined opening so that the exhaust gas is supplied to the turbine of the second supercharger. The above-mentioned predetermined opening is set to an appropriate value in advance by, for example, experiments. By doing so, the second supercharger is driven using the exhaust of the engine. Accordingly, the intake pressure rises and the intake air temperature rises, and the intake control valve and the bypass valve are warmed up. Therefore, the control device for the internal combustion engine can promote the defrosting of the intake control valve and the bypass valve.

  In one aspect of the control apparatus for an internal combustion engine, the valve control unit performs opening control of the exhaust control valve by a predetermined opening when icing occurs in the intake control valve, and the second supercharging. The opening degree of the bypass valve is controlled so that the intake air temperature or the intake pressure downstream of the compressor of the machine falls within a predetermined setting range. The “set range” refers to a predetermined set temperature or set pressure, and the set temperature and set pressure may have a predetermined width (value range). The set temperature and the set pressure are set in advance to appropriate values or value ranges based on, for example, experiments. In this aspect, the control device for the internal combustion engine can prevent an excessive increase in the intake air temperature or the intake pressure by controlling the bypass valve based on the intake air temperature or the intake pressure.

  In another aspect of the control apparatus for an internal combustion engine, the valve control means may be configured to detect an intake air temperature or an intake air downstream of a compressor of the second supercharger when icing occurs in the intake control valve and the bypass valve. The opening degree of the exhaust control valve is controlled so that the pressure falls within a predetermined setting range. In this aspect, the control device for the internal combustion engine can prevent an excessive increase in the intake air temperature or the intake pressure by controlling the exhaust control valve based on the intake air temperature or the intake pressure.

  In another aspect of the control device for an internal combustion engine, the valve control means closes the bypass valve and freezes the compressor of the second supercharger when the intake control valve is frozen. The opening degree of the exhaust control valve is controlled so that the intake air temperature or the intake air pressure falls within a predetermined set range. In this aspect, the control device for the internal combustion engine closes the bypass valve and closes the bypass passage, thereby further promoting the increase of the intake air temperature and the intake pressure downstream of the compressor when the exhaust control valve is opened. it can.

  In a preferred example of the control apparatus for an internal combustion engine, the first supercharger and the second supercharger are arranged in parallel to the intake passage and the exhaust passage. By doing in this way, the control apparatus of an internal combustion engine can be applied suitably to this invention.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[overall structure]
First, a schematic configuration of a control device for an internal combustion engine according to each embodiment of the present invention will be described.

  FIG. 1 is a schematic diagram showing the configuration of a control device 100 for an internal combustion engine according to each embodiment of the present invention. In FIG. 1, solid arrows indicate gas flow, and broken arrows indicate signal input / output.

  The vehicle mainly includes an air cleaner 2, an intake passage 3, turbochargers 4 and 5, an intake control valve 6, an intake bypass valve 7, an internal combustion engine 8, an exhaust passage 10, and an EGR passage 11. , EGR valve 14, exhaust control valve 15, ECU 22, and intake bypass passage 31.

  The air cleaner 2 purifies air (intake air) acquired from the outside and supplies it to 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 provided in the intake passage 3b. Is arranged. That is, the intake passage 3 communicates with the compressors 4a and 4b. The compressors 4a and 5a compress the intake air that passes through the intake passages 3a and 3b, respectively.

  An intake control valve 6 is provided in the intake passage 3b. The intake control valve 6 is controlled to open and close by a control signal S6 supplied from the ECU 22, and is configured to be able to adjust the flow rate of intake air passing through the intake passage 3b. For example, the ECU 22 switches the flow / blocking of the intake air in the intake passage 3b by opening and closing the intake control valve 6.

  One end of the intake bypass passage 31 is connected to the intake passage 3b between the compressor 5a and the intake control valve 6, and the other end is connected to the intake passage 3 between the air cleaner 2 and the compressor 4a. That is, the intake bypass passage 31 bypasses the downstream side of the compressor 5a and the upstream side of the compressor 4a.

  An intake bypass valve 7 is provided in the intake bypass passage 31. The intake bypass valve 7 is controlled to be opened and closed by a control signal S7 supplied from the ECU 22, and opens to bypass the intake air passing downstream of the compressor 5a upstream of the compressor 4a.

  The internal combustion engine 8 is a device that generates power by burning an air-fuel mixture of intake air and fuel supplied from the intake passage 3. The internal combustion engine 8 is configured by, for example, a gasoline engine or a diesel engine having four cylinders. The exhaust gas generated by the combustion in the internal combustion engine 8 is discharged to the exhaust passage 10.

  An EGR passage 11 is connected in the exhaust passage 10. The EGR passage 11 has one end connected to the exhaust passage 10 and the other end connected to the intake passage 3. The EGR passage 11 is a passage for returning exhaust gas (EGR gas) to the intake system. Specifically, the EGR passage 11 is provided with an EGR cooler 12, an EGR valve 14, a bypass passage 11a, and a bypass valve 13. The EGR cooler 12 is a device that cools the EGR gas, and the EGR valve 14 is a valve that adjusts the flow rate of the EGR gas that passes through the EGR passage 11, in other words, the amount of EGR gas that is recirculated to the intake system (that is, the EGR rate). Is the valve. In this case, the opening degree of the EGR valve 14 is controlled by a control signal supplied from the ECU 22. The bypass passage 11a is a passage that bypasses the EGR cooler 12, and a bypass valve 13 is provided on the passage. The bypass valve 13 adjusts the flow rate of EGR gas passing through the bypass passage 11a. In FIG. 1, since the EGR valve 14 is set to be closed, the EGR gas is not recirculated.

  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. That is, the exhaust passage communicates with the turbines 4a and 4b. 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 corresponds to the first supercharger of the present invention, and is configured as a low-capacity low-speed supercharger having a large supercharging capability in a low / medium speed range. The turbocharger 5 corresponds to the second supercharger of the present invention, and is configured as a large-capacity high-speed supercharger having a large supercharging capability in a medium to high speed range.

  Further, an exhaust control valve 15 is provided in the exhaust passage 10b. The exhaust control valve 15 is controlled to be opened and closed by a control signal S15 supplied from the ECU 22, and is configured to be able to adjust the flow rate of exhaust gas passing through the exhaust passage 10b. For example, by opening and closing the exhaust control valve 15, it is possible to switch the flow / blocking of the exhaust gas in the exhaust passage 10b.

  When the intake control valve 6, the exhaust control valve 15, and the intake bypass valve 7 are all closed, intake and exhaust gas are supplied only to the turbocharger 4, and the turbocharger 5 is supplied to the turbocharger 5. Intake and exhaust gas are not supplied. Therefore, in this case, only the turbocharger 4 operates, and the turbocharger 5 does not operate. On the other hand, for example, when either the intake control valve 6 or the intake bypass valve 7 is open and the exhaust control valve 15 is open, intake and exhaust gas are supplied to both the turbochargers 4 and 5. . Therefore, in this case, both turbochargers 4 and 5 operate.

  The temperature sensor 20 is installed downstream of the compressor 5a on the intake passage 3b and detects the temperature of the passing intake gas (hereinafter referred to as “intake air temperature Tb”). The temperature sensor 20 supplies the detected intake air temperature Tb to the ECU 22.

  The water temperature sensor 21 is a sensor that detects the water temperature of cooling water for cooling the engine 8 (hereinafter referred to as “water temperature Ta”). The water temperature sensor 21 supplies the detected water temperature Ta to the ECU 22.

  The output device 23 is a device that performs display or audio output based on a control signal S23 of the ECU 22. The output device 23 corresponds to, for example, a navigation device provided in a vehicle, a dedicated lamp for notifying a failure, or an audio output device.

  The ECU 22 includes a CPU, a ROM, a RAM, an A / D converter, and the like (not shown). The ECU 22 performs in-vehicle control based on output supplied from various sensors in the vehicle. For example, the ECU 22 controls the intake control valve 6, the exhaust control valve 15, and the intake bypass valve 7 to determine whether or not these are frozen. In addition, when the ECU 22 determines that icing has occurred, the ECU 22 performs control for promoting the elimination of icing. Therefore, the ECU 22 is an example of the icing estimation means and the valve control means in the present invention.

  In the following first to sixth embodiments, control of the ECU 22 when the present invention is applied will be described.

[First Embodiment]
First, control executed by the ECU 22 in the first embodiment will be described. In the first embodiment, the ECU 22 determines whether the abnormal operation of the intake control valve 6, the exhaust control valve 15, and the intake bypass valve 7 (hereinafter, these valves are collectively referred to as “control valves”) is caused by icing. The determination is made based on the water temperature Ta. Thereby, the ECU 22 prevents the evacuation operation from being continued after the freezing is eliminated.

  This will be specifically described. First, after starting the vehicle, the ECU 22 determines whether or not each control valve has an abnormal operation. For example, the ECU 22 operates the control valve based on the control signals S6, S7, and S15, and monitors its behavior to determine whether each control valve is operating, that is, whether each control valve is fixed. Judge whether or not. For example, the ECU 22 may determine whether or not the control valve is stuck based on the presence or absence of a change in the voltage value output to the control valve. Alternatively, the ECU 22 may determine whether or not the control valve is stuck based on the output values of various sensors after operating the control valve, for example, whether or not the intake air temperature Tb or the like has changed. Alternatively, an opening sensor may be provided for each control valve, and it may be determined whether or not the control valve is stuck based on the detected value.

  When the ECU 22 determines that the control valve has an abnormal operation, the ECU 22 starts a retreat operation, that is, an operation that guarantees a minimum traveling ability that can avoid a danger and travel on the shoulder.

  Next, after completing the warm-up of the control valve, the ECU 22 executes the control valve abnormality determination (hereinafter also referred to as “control valve abnormality re-determination”). Specifically, the ECU 22 first monitors the water temperature Ta until the water temperature Ta detected by the water temperature sensor 21 or the like becomes equal to or higher than a predetermined water temperature (hereinafter referred to as “first reference temperature T1”). The first reference temperature T1 is set, for example, within a cooling water temperature range in which icing is eliminated when icing occurs in the control valve. Specifically, the first reference temperature T1 is set to an appropriate value based on experiments or the like. Then, when the water temperature Ta reaches the first reference temperature T1, the ECU 22 performs the control valve abnormality determination again.

  If the control valve abnormality re-determination determines that the control valve operates normally, the ECU 22 switches from the evacuation operation to the normal operation. In other words, in this case, the ECU 22 determines that the previous operation abnormality of the control valve is a temporary operation abnormality caused by freezing of the control valve, and that the freezing has been resolved at present. On the other hand, if it is determined that there is an operation abnormality in the control valve in the abnormality determination again, the operation abnormality is caused by factors other than freezing, such as an abnormality in the control system of the ECU 22 and the control valve or a breakage of the control valve. It is determined that an abnormal operation, that is, a failure has occurred. In this case, the ECU 22 notifies the occupant of the failure by displaying, for example, a failure on the output device 23.

  By doing in this way, ECU22 can specify whether it is an operation abnormality resulting from freezing. Further, the ECU 22 can return to the normal operation after the freezing is eliminated in the case of an abnormal operation due to freezing. That is, the ECU 22 can prevent the evacuation operation from being continued unnecessarily after the icing is eliminated in the case of an abnormal operation due to icing.

(Processing flow)
Next, a processing procedure in the first embodiment will be described. FIG. 2 is an example of a flowchart showing a procedure of processing executed by the ECU 22 in the present embodiment. ECU22 repeatedly performs the process of the flowchart shown in FIG. 2 according to a predetermined period.

  First, the ECU 22 detects that the ignition is turned on (step S101). As a result, the engine 8 is started.

  Next, the ECU 22 determines whether the control valve is abnormal (step S102). That is, the ECU 22 determines whether or not the intake control valve 6, the exhaust control valve 15, and the intake bypass valve 7 are appropriately operated based on the control signals S6, S7, and S15.

  If it is determined that the control valve is normal (step S103; Yes), the ECU 22 performs normal operation (step S104). That is, in this case, the ECU 22 does not limit the function of the vehicle.

  On the other hand, when it is determined that the control valve is not normal (step S103; No), the ECU 22 starts the retreat operation (step S105).

  Then, the ECU 22 acquires the water temperature Ta after the start of the retreat operation (step S106). The ECU 22 acquires the water temperature Ta from, for example, the water temperature sensor 21.

  Next, the ECU 22 performs warm-up determination (step S107). That is, the ECU 22 determines whether or not the water temperature Ta is greater than the first reference value T1. Thus, the ECU 22 considers the case where the control valve is frozen, and determines whether or not the vehicle has reached a state of deicing based on the water temperature Ta.

  If the water temperature Ta is greater than the first reference value T1 (step S107; Yes), the ECU 22 performs a control valve abnormality redetermination (step S108). That is, the ECU 22 executes the process of step S102 again in order to determine whether the previous operation abnormality of the control valve is an operation abnormality caused by freezing.

  On the other hand, when the water temperature Ta does not reach the first reference value T1 (step S107; No), the ECU 22 continuously monitors the water temperature Ta until the water temperature Ta reaches the first reference value T1, and then re-determines the control valve abnormality. I do.

  If the result of the control valve abnormality redetermination in step S108 is normal (step S109; Yes), the ECU 22 starts normal operation (step S104). That is, in this case, the ECU 22 determines that the operation abnormality of the control valve found in step S102 is an operation abnormality caused by freezing, and that the freezing has been eliminated. Thereby, the ECU 22 can prevent the evacuation operation from being continued unnecessarily.

  On the other hand, when the result of the control valve abnormality re-determination is not normal (step S109; No), the ECU 22 displays a failure (step S110). That is, in this case, the ECU 22 notifies the occupant that a failure has occurred by the output device 23.

[Second Embodiment]
In the first embodiment, when detecting an operation abnormality of the control valve, the ECU 22 performs the control valve abnormality redetermination after the water temperature Ta is warmed up. On the other hand, in the second embodiment, the ECU 22 does not execute the control valve abnormality redetermination when it is clearly determined that icing does not occur. Thereby, ECU22 notifies a passenger | crew of that early, when failure has occurred in the control valve.

  The second embodiment will be specifically described below. First, the ECU 22 measures a water temperature Ta when the engine 8 is started (hereinafter referred to as “starting water temperature Ta1”).

  Next, the ECU 22 makes a prediction (hereinafter referred to as “icing prediction determination”) as to whether or not the control valve will freeze. For example, the ECU 22 performs the icing prediction determination based on whether or not the starting water temperature Ta1 is at a water temperature at which icing of the control valve can occur. Specifically, the ECU 22 determines whether or not the starting water temperature Ta1 is lower than a predetermined reference water temperature (hereinafter referred to as “second reference temperature T2”). The second reference temperature T2 is set to, for example, an upper limit value of the water temperature at which icing of the control valve can occur, and is specifically set in advance based on experiments or the like.

  Then, when the starting water temperature Ta1 is at a water temperature at which icing of the control valve can occur, that is, when the starting water temperature Ta1 is lower than the second reference temperature T2, as in the first embodiment, the ECU 22 After completion of warming up, the control valve abnormality redetermination is executed. On the other hand, when the starting water temperature Ta1 is not at a water temperature at which icing of the control valve can occur, that is, when the starting water temperature Ta1 is equal to or higher than the second reference temperature T2, the ECU 22 does not wait for the control valve to warm up. It is determined that a malfunction of the control valve has occurred due to a failure. Then, the ECU 22 notifies the occupant to that effect by the output device 23.

  By doing so, the ECU 22 can prevent the control valve abnormality re-determination from waiting until the water temperature Ta rises unnecessarily when the outside air temperature is high and no freezing occurs. That is, the ECU 22 can notify the occupant of the abnormality of the control valve due to the failure at an early stage.

(Processing flow)
Next, a processing procedure in the second embodiment will be described. FIG. 3 is an example of a flowchart showing a procedure of processing executed by the ECU 22 in the present embodiment. ECU22 repeatedly performs the process of the flowchart shown in FIG. 3 according to a predetermined period.

  First, after confirming that the ignition is on (step S201), the ECU 22 detects the starting water temperature Ta1 (step S202).

  Next, the ECU 22 determines whether the control valve is abnormal (step 203), and starts normal operation (step S205) when it is determined to be normal (step S204; Yes). On the other hand, when determining that it is not normal (step S204; No), the ECU 22 starts the retreat operation (step S206).

  Then, after the start of the evacuation operation, the ECU 22 performs icing prediction determination (step S207). That is, the ECU 22 determines whether or not the starting water temperature Ta1 is smaller than the second reference value T2.

  If the starting water temperature Ta1 is smaller than the second reference value T2 (step S207; Yes), the ECU 22 determines that there is a possibility that an abnormal operation of the control valve has occurred due to freezing of the control valve. , Steps S208 to S212 are executed. That is, the ECU 22 acquires the water temperature Ta (step S208), performs warm-up determination (step S209), and performs control valve abnormality redetermination (step S210). When the result of the control valve abnormality redetermination is normal (step S211; Yes), the ECU 22 starts normal operation (step S205). On the other hand, if not normal (step S211; No), the ECU 22 displays a failure (step S212).

  On the other hand, when the starting water temperature Ta1 is equal to or higher than the second reference value T2 (step S207; No), the ECU 22 determines that there is no possibility that an abnormal operation of the control valve has occurred due to freezing of the control valve, Immediately, failure display is performed (step S212).

  As described above, the ECU 22 prompts the occupant that there is a system abnormality promptly without re-determination of the control valve abnormality when there is no risk of abnormal operation of the control valve due to high outside air temperature or the like. You can be notified.

[Third Embodiment]
In the second embodiment, when it is determined that icing does not occur clearly, the ECU 22 promptly notifies the occupant that the system is abnormal without executing the control valve abnormality redetermination. In the third embodiment, instead of this, or in addition to this, the ECU 22 gives the occupant its control valve warm-up and control valve abnormality re-determination (hereinafter, these processes are also referred to as “freezing determination”). In the case of abnormal operation of the control valve due to freezing, a log is recorded. Thus, the ECU 22 prevents an occupant from misidentifying an operation abnormality caused by icing as an operation abnormality caused by a failure, and enables a vehicle mechanic to be notified of the cause of the operation abnormality.

  The third embodiment will be specifically described below. First, when starting the icing determination, the ECU 22 outputs that the icing determination is being performed by the output device 23.

  Thereafter, when it is determined by the control valve abnormality re-determination that the operation of the control valve is normal, the ECU 22 cancels the notification by the output device 23 that the icing determination is being performed. Then, the ECU 22 saves a log indicating that there is freezing in a ROM or the like, and then starts normal operation.

  Thus, by indicating that the icing determination is being performed, the ECU 22 can notify the driver of the possibility that the deterioration in drivability is a temporary abnormality due to icing. Further, when an operation abnormality due to icing occurs and the evacuation operation is performed, the driver may determine that there is a failure and request a repair from a dealer or the like. However, a dealer mechanic or the like cannot identify an abnormal operation when the ice is melted at the time of repair. On the other hand, in the third embodiment, the ECU 22 can notify a maintenance staff or the like that the cause of the operation abnormality is freezing by leaving a log indicating that freezing has occurred.

(Processing flow)
Next, a processing procedure in the third embodiment will be described. FIG. 4 is an example of a flowchart showing a procedure of processing executed by the ECU 22 in the present embodiment. ECU22 repeatedly performs the process of the flowchart shown in FIG. 4 according to a predetermined period. Steps S301 to S305 are the same as steps S101 to S105 shown in FIG.

  After starting the retreat operation, the ECU 22 displays a display indicating that the icing is being determined (step S306). For example, the ECU 22 transmits a control signal S23 to cause the output device 23 to display that icing is being determined.

  Thereafter, the ECU 22 performs icing determination. That is, the ECU 22 acquires the water temperature Ta (step S307), performs warm-up determination (step S308), and then performs control valve abnormality redetermination (step S309).

  If the result of the control valve abnormality re-determination is normal (step S310; Yes), the ECU 22 turns off the display during icing determination (step S311). That is, the ECU 22 cancels the display performed in step S306.

  Next, the ECU 22 stores an icing log (step S312). That is, the ECU 22 saves a record that there has been freezing in a ROM or other external memory. Thereafter, the ECU 22 performs a normal operation (step S304).

  On the other hand, when it is determined that the control valve is not normal by redetermination of the control valve (step S310; No), the ECU 22 displays a failure (step S313). In other words, the ECU 22 determines that there is an abnormal operation of the control valve due to the failure, and displays a display indicating that there is a failure from the display during the icing determination. Then, the ECU 22 continues the retreat operation.

  As described above, the ECU 22 prevents an occupant from misidentifying an operation abnormality caused by icing as an operation abnormality caused by a failure, and enables the vehicle mechanic to be notified of the cause of the operation abnormality.

[Fourth Embodiment]
In the first to third embodiments, the ECU 22 waits until the water temperature Ta reaches a temperature at which the control valve is deiced in the icing determination. Instead of this, or in addition to this, in the fourth embodiment, the ECU 22 controls the exhaust control valve 15 to positively supercharge the exhaust of the engine 8 to the turbocharger 5 and control the intake air. The ice melting of the valve 6 and the intake bypass valve 7 is promoted. Hereinafter, in the fourth embodiment, the control of the exhaust control valve 15 executed by the ECU 22 is also referred to as “ice removal control”.

  The fourth embodiment will be specifically described below. First, the ECU 22 determines whether or not icing is predicted in the intake control valve 6 and the intake bypass valve 7. For example, the ECU 22 controls the intake control valve 6 and the intake bypass valve 7 to confirm the presence or absence of these abnormal operations. Further, as in the second embodiment, the ECU 22 predicts freezing based on whether or not the starting water temperature Ta1 is lower than the second reference temperature T2.

  Next, the ECU 22 determines abnormality of the exhaust control valve 15. When there is an operation abnormality in the exhaust control valve 15, the ECU 22 determines the abnormality of the exhaust control valve 15 again after a predetermined time width elapses. The predetermined time width is set to a time width required for the exhaust control valve 15 to melt ice. For example, the predetermined time width is set in advance based on experiments or the like, and is stored in the ROM or the like of the ECU 22. Since the exhaust gas of the engine 8 is supplied to the exhaust control valve 15, the ice is defrosted before the intake control valve 6 and the intake bypass valve 7.

  And ECU22 will open the exhaust control valve 15 only by predetermined opening, when it is judged that it is normal by the above-mentioned abnormality determination or another abnormality determination. The predetermined opening is set, for example, within a range of opening that does not affect other controls. Specifically, the predetermined opening is set to an appropriate value based on, for example, experiments and is held in the ROM of the ECU 22 or the like. And ECU22 returns the opening degree of the exhaust control valve 15 to the original after predetermined time width progress. The predetermined time width is set to a time width required for the intake control valve 6 and the intake bypass valve 7 to melt. For example, the predetermined time width is set in advance based on experiments or the like, and is stored in the ROM or the like of the ECU 22.

  Thus, since the exhaust gas from the engine 8 passes through the exhaust passage 10b, the turbocharger 5 is supplied (supercharged) with the exhaust gas passing through the exhaust control valve 15. As a result, the turbocharger 5 is driven, and the intake pressure on the downstream side of the compressor 5a is increased. Further, the intake air temperature Tb also rises due to an increase in intake pressure and exhaust heat. As a result, the intake control valve 6 and the intake bypass valve 7 downstream of the compressor 5a are warmed up, and the defrosting of the intake control valve 6 and the intake bypass valve 7 is promoted. Therefore, the ECU 22 can shorten the time required to return to normal operation when an abnormal operation of the control valve occurs due to icing.

  This effect will be further supplemented. FIG. 5 shows an example of a graph of the time change of the intake air temperature Tb after the engine 8 is started. A graph 70 shows a graph of the time change of the intake air temperature Tb when the ECU 22 performs the ice melting control according to the fourth embodiment, and a graph 71 shows the intake air when the ECU 22 controls according to the first to third embodiments. The graph of the time change of temperature Tb is shown.

  As shown in FIG. 5, in the graph 70, the ECU 22 opens the exhaust control valve 15 and supplies exhaust gas to the turbocharger 5, so that the intake air temperature Tb rises faster than the graph 71. Therefore, in the fourth embodiment, the ECU 22 can warm up the intake control valve 6 and the intake bypass valve 7 early.

(Processing flow)
Next, a processing procedure in the fourth embodiment will be described. FIG. 6 is an example of a flowchart showing a procedure of processing executed by the ECU 22 in the fourth embodiment. ECU22 repeatedly performs the process of the flowchart shown in FIG. 6 according to a predetermined period.

  First, the ECU 22 determines whether or not icing is predicted (step S401). For example, the ECU 22 detects these operational abnormalities by driving and controlling the intake control valve 6 and the intake bypass valve 7 and also predicts icing in the intake control valve 6 or the intake bypass valve 7 based on the starting water temperature Ta1. It is determined whether or not.

  When icing is predicted (step S401; Yes), the ECU 22 determines whether the exhaust control valve 15 is abnormal (step S402). On the other hand, when icing is not predicted (step S401; No), ECU22 complete | finishes the process of a flowchart.

  Next, when it is determined in the abnormality determination of the exhaust control valve 15 that the exhaust control valve 15 is abnormal (step S402; Yes), the ECU 22 monitors whether or not a predetermined time has passed (step S403). That is, after judging the abnormality of the exhaust control valve 15, the ECU 22 waits for a time width during which the exhaust control valve 15 is melted by the exhaust heat of the engine 8.

  On the other hand, when it is determined that there is no abnormality in the exhaust control valve 15 (step S402; No), the ECU 22 advances the process to step S405.

  Then, when a predetermined time width has elapsed after the abnormality determination of the exhaust control valve 15 (step S403; Yes), the ECU 22 performs an abnormality re-determination of the exhaust control valve 15 (step S404). That is, the ECU 22 performs the abnormality determination again after sufficiently warming up the exhaust control valve 15.

  If it is determined that the exhaust control valve 15 is normal by re-determination of the exhaust control valve 15 (step S404; Yes), the ECU 22 opens the exhaust control valve 15 by a predetermined opening (step S405). As a result, the exhaust gas that has passed through the exhaust control valve 15 is supplied to the turbocharger 5. As a result, the intake air temperature Tb increases and the intake pressure also increases.

  On the other hand, when it is determined again that the exhaust control valve 15 is abnormal (step S404; No), the ECU 22 determines that the exhaust control valve 15 is faulty and ends the process of the flowchart.

  Next, the ECU 22 monitors whether or not a predetermined time width has elapsed after the exhaust control valve 15 is opened (step S406). If the predetermined time width has not elapsed (step S406; No), the ECU 22 continuously monitors whether the predetermined time width has elapsed. At this time, the predetermined time width is set to a time width required for the intake control valve 6 and the intake bypass valve 7 to melt after the exhaust control valve 15 is opened due to an increase in the intake temperature Tb or the like. .

  Then, after a predetermined time width has elapsed after the exhaust control valve 15 is opened (step S406; Yes), the ECU 22 ends the ice melting control (step S407). That is, the ECU 22 closes the exhaust control valve 15 by the above-described predetermined opening. Then, the ECU 22 ends the process of the flowchart.

  As described above, the ECU 22 can shorten the time required to return to normal operation when an abnormal operation of the control valve occurs due to icing.

[Fifth Embodiment]
In the fourth embodiment, the ECU 22 performs the ice melting control by controlling the exhaust control valve 15. In addition, in the fifth embodiment, when the intake bypass valve 7 is not frozen, the intake bypass valve 7 is further controlled. As a result, the ECU 22 further promotes the defrosting of the intake control valve 6 and suppresses an excessive increase in the intake air temperature Tb and the like.

  The fifth embodiment will be specifically described below. First, the ECU 22 determines whether only the intake control valve 6 is predicted to freeze. For example, the ECU 22 determines that the intake control valve 6 may be frozen if the starting water temperature Ta1 is lower than the second reference temperature T2 or if the intake air temperature Tb is lower than a predetermined temperature. Furthermore, the ECU 22 controls whether to drive the exhaust control valve 15, the intake bypass valve 7, and the intake control valve 6 and confirms abnormal operation of these, thereby determining whether or not icing is predicted only in the intake control valve 6. .

  When freezing of only the intake control valve 6 is predicted, the ECU 22 opens the exhaust control valve 15 by a predetermined opening degree, as in the fourth embodiment. As a result, exhaust gas is supplied to the turbocharger 5 and the intake air temperature Tb rises. Further, when the turbocharger 5 is driven, the intake pressure also increases.

  Then, the ECU 22 closes the intake bypass valve 7 when the intake air temperature Tb is lower than a predetermined temperature set in advance (hereinafter referred to as “set temperature T3”). The set temperature T3 is set within a temperature range in which the intake control valve 6 can be deiced and within an appropriate temperature range as the intake air temperature. Specifically, the set temperature T3 is set to an appropriate value based on experiments or the like. The As a result, the intake gas supplied from the compressor 5a does not flow into the intake bypass passage 31, and the increase of the intake pressure downstream of the compressor 5a is promoted and the temperature rise of the intake air temperature Tb is also promoted. Therefore, the ECU 22 can promote the defrosting of the intake control valve 6 by closing the intake bypass valve 7.

  On the other hand, the ECU 22 opens the intake bypass valve 7 when the intake air temperature Tb becomes higher than the set temperature T3. Thereby, the ECU 22 prevents the intake air temperature Tb and the intake pressure from excessively rising, and keeps the intake air temperature Tb at an appropriate temperature, that is, near the set temperature T3. That is, the ECU 22 prevents, for example, the occurrence of breakage of parts or other control problems due to an excessive increase in the intake air temperature Tb and the intake air pressure.

  And ECU22 complete | finishes ice-melting control, when predetermined time width passes after the exhaust_gas | exhaustion control valve 15 valve opening. The predetermined time width described above is set to a time width necessary for the intake control valve 6 to melt ice based on experiments and the like.

  In this way, the ECU 22 can further increase the intake temperature Tb by controlling the intake bypass valve 7 in addition to the exhaust control valve 15. This will be supplemented with reference to FIG. FIG. 7 shows an example of a graph of the time change of the intake air temperature Tb after the engine 8 is started. Specifically, the graph 70x shows a graph of the time change of the intake air temperature Tb when the ECU 22 performs the ice melting control according to the fifth embodiment, and the graph 71 shows the graph 71 by the ECU 22 according to the first to third embodiments. The graph of the time change of the intake air temperature Tb at the time of controlling is shown.

  As shown in the graph 70x, when the exhaust control valve 15 is opened and the intake bypass valve 7 is closed, the intake air temperature Tb reaches the set temperature T3 early due to the drive of the turbocharger 5. Further, after reaching the set temperature T3, the ECU 22 appropriately opens and closes the intake bypass valve 7, so that the intake temperature Tb is maintained near the set temperature T3. In this way, the ECU 22 can promote the defrosting of the intake control valve 6 early and appropriately.

(Processing flow)
Next, a processing procedure in the fifth embodiment will be described. FIG. 8 is an example of a flowchart showing a procedure of processing executed by the ECU 22 in the fifth embodiment. ECU22 repeatedly performs the process of the flowchart shown in FIG. 8 according to a predetermined period.

  First, the ECU 22 determines whether or not icing is predicted (step S501). For example, the ECU 22 controls whether or not the intake control valve 6 is operating abnormally by controlling the intake control valve 6 and whether or not icing is predicted in the intake control valve 6 based on the water temperature Ta or the intake temperature Tb. judge.

  Next, the ECU 22 determines whether the exhaust control valve 15 and the intake bypass valve 7 are abnormal (step S502). For example, the ECU 22 determines these abnormalities by controlling the exhaust control valve 15 and the intake bypass valve 7 based on the control signal S15 and the control signal S7.

  When it is determined that the exhaust control valve 15 and the intake bypass valve 7 are normal (step S502; Yes), the ECU 22 determines that only the intake control valve 6 is predicted to freeze, and opens the exhaust control valve 15 to a predetermined opening degree. Only the valve is opened (step S503). Thereby, the exhaust gas of the engine 8 is supplied to the turbocharger 5, and the intake air temperature Tb and the intake pressure rise. On the other hand, when it is determined that either the exhaust gas switching valve 15 or the intake bypass valve 7 is not normal (step S502; No), the ECU 22 ends the process of the flowchart.

  Next, the ECU 22 determines whether or not the intake air temperature Tb is higher than the set temperature T3 (step S504). Thereby, the ECU 22 determines whether or not the intake air temperature Tb is at an appropriate temperature.

  When the intake air temperature Tb is higher than the set temperature T3 (step S504; Yes), the ECU 22 opens the intake bypass valve 7 (step S505). Thereby, the ECU 22 prevents an excessive increase in the intake air temperature Tb and the intake air pressure.

  On the other hand, when the intake air temperature Tb is equal to or lower than the set temperature T3 (step S504; No), the ECU 22 closes the intake bypass valve 7 (step S506). Thereby, the ECU 22 can further promote the increase of the intake air temperature Tb and the intake air pressure, and promote the defrosting of the intake control valve 6.

  Then, after the end of step S505 or step S506, the ECU 22 determines whether or not a predetermined time width has elapsed since the exhaust control valve 15 was opened (step S507). The above-mentioned predetermined time width is set to a time width necessary for the intake control valve 6 to melt ice. If the ECU 22 determines that the predetermined time width has not elapsed (step S507; No), the ECU 22 returns the process to step S504 again, and controls the opening and closing of the intake bypass valve 7 based on the intake air temperature Tb ( Steps S504 to S506). Thereby, the ECU 22 reliably defrosts the intake control valve 6.

  When the predetermined time width has elapsed (step S507; Yes), the ECU 22 ends the ice-breaking control (step S508). As described above, the ECU 22 can enable the deicing of the intake control valve 6 more quickly and appropriately.

[Sixth Embodiment]
In the fifth embodiment, the ECU 22 controls the opening and closing of the intake bypass valve 7 after the exhaust control valve 15 is opened, thereby maintaining the intake temperature Tb at the set temperature T3 and promoting the defrosting of the intake control valve 6. It was. Instead, in the sixth embodiment, after the intake bypass valve 7 is closed, the opening and closing of the exhaust control valve 15 is controlled. Also by this, the ECU 22 appropriately keeps the intake air temperature Tb at the set temperature T3, and promotes defrosting of the intake control valve 6.

  The sixth embodiment will be specifically described below. First, the ECU 22 determines whether or not icing is predicted only in the intake control valve 6. For example, the ECU 22 determines that the intake control valve 6 may be frozen if the starting water temperature Ta1 is lower than the second reference temperature T2 or if the intake air temperature Tb is lower than a predetermined temperature. Furthermore, the ECU 22 controls whether to drive the exhaust control valve 15, the intake bypass valve 7, and the intake control valve 6 and confirms abnormal operation of these, thereby determining whether or not icing is predicted only in the intake control valve 6. .

  When icing is predicted only for the intake control valve 6, the ECU 22 closes the intake bypass valve 7 when icing is predicted only for the intake control valve 6.

  Next, the ECU 22 acquires the intake air temperature Tb, and opens the exhaust control valve 15 when the intake air temperature Tb is equal to or lower than the set temperature T3. In this case, the exhaust gas that has passed through the exhaust control valve 15 is supercharged to the turbocharger 5, and the turbocharger 5 is driven. As a result, the intake pressure on the downstream side of the compressor 5a increases and the intake temperature Tb rises. Further, since the intake bypass valve 7 is closed, the intake pressure and the intake air temperature Tb on the downstream side of the compressor 5a are promoted.

  On the other hand, the ECU 22 closes the exhaust control valve 15 when the intake air temperature Tb is higher than the set temperature T3. As a result, the exhaust gas from the engine 8 is not supplied to the turbocharger 5. Therefore, the ECU 22 can prevent an excessive increase in the intake pressure and the intake temperature Tb.

  As described above, the ECU 22 controls the opening and closing of the exhaust control valve 15 on the basis of the intake temperature Tb and the set temperature T3, so that the intake air intake until the defrosting of the intake control valve 6 is predicted passes. The temperature Tb is kept at the set temperature T3. As a result, similar to the graph 70x of FIG. 7 described in the fifth embodiment, after the engine 8 is started, the intake air temperature Tb rises quickly and changes around the set temperature T3. Therefore, the ECU 22 can appropriately perform the ice melting of the intake control valve 6.

(Processing flow)
Next, a processing procedure in the sixth embodiment will be described. FIG. 9 is an example of a flowchart showing a procedure of processing executed by the ECU 22 in the present embodiment. The ECU 22 repeatedly executes the process of the flowchart shown in FIG. 9 according to a predetermined cycle.

  First, as in the fifth embodiment, the ECU 22 determines whether or not icing is predicted (step S601). For example, the ECU 22 controls whether or not the intake control valve 6 is operating abnormally by controlling the intake control valve 6 and whether or not icing is predicted in the intake control valve 6 based on the water temperature Ta or the intake temperature Tb. judge.

  If icing is predicted (step S601; Yes), the ECU 22 determines whether the exhaust control valve 15 and the intake bypass valve 7 are abnormal (step S602). When icing is not predicted (step S601; No), or when it is determined that the exhaust control valve 15 and the intake bypass valve 7 are abnormal (step S602; No), the ECU 22 ends the process of the flowchart.

  If it is determined that the exhaust control valve 15 and the intake bypass valve 7 are normal (step S602; Yes), the ECU 22 closes the intake bypass valve 7 (step S603). Thereby, the ECU 22 promotes the increase of the intake pressure and the intake temperature Tb when the exhaust control valve 15 is opened.

  Next, the ECU 22 determines whether or not the intake air temperature Tb is higher than the set temperature T3 (step S604). If the intake air temperature Tb is higher than the set temperature T3 (step S604; Yes), the ECU 22 closes the exhaust control valve 15 (step S605). Thereby, the ECU 22 suppresses an excessive increase in the intake air temperature Tb and the like.

  On the other hand, when the intake air temperature Tb is equal to or lower than the set temperature T3 (step S604; No), the ECU 22 opens the exhaust control valve 15 (step S606). Thereby, ECU22 can supercharge the exhaust gas from the engine 8 to the turbo supercharger 5, and can raise intake pressure and intake temperature Tb.

  Then, the ECU 22 determines whether or not a predetermined time width has elapsed since the intake bypass valve 7 was closed (step S607). The above-mentioned predetermined time width is set to a time width necessary for the intake control valve 6 to melt ice. If the ECU 22 determines that the predetermined time width has not elapsed (step S607; No), the ECU 22 returns the process to step S604 again, and controls the opening / closing of the exhaust control valve 15 based on the intake air temperature Tb ( Steps S604 to S606). Thereby, the ECU 22 reliably defrosts the intake control valve 6.

  When the predetermined time width has elapsed (step S607; Yes), the ECU 22 ends the ice-melting control (step S608). As described above, the ECU 22 can quickly and appropriately defrost the intake control valve 6.

[Modification 1]
The present invention is not limited to application to a system in which two turbochargers 4 and 5 are arranged in parallel in the intake passage 3 and the exhaust passage 10. The present invention can also be applied to a system in which two turbochargers (a high pressure turbocharger and a low pressure turbocharger) are arranged in series in an intake passage and an exhaust passage. That is, even for a system in which two turbochargers are arranged in series, the ECU 22 performs the intake control valve 6, the intake bypass valve 7, and the By controlling the exhaust control valve 15, it is possible to specify that the operation is abnormal due to icing, promote ice melting, or the like.

[Modification 2]
In the fifth embodiment and the sixth embodiment described above, the ECU 22 controls the opening and closing of the intake bypass valve 7 and the exhaust control valve 15 based on the intake air temperature Tb. However, the method to which the present invention is applicable is not limited to this. For example, the ECU 22 may control the intake bypass valve 7 and the exhaust control valve 15 based on the intake pressure on the downstream side of the compressor 5a instead of the intake temperature Tb. In this case, for example, the control device 100 for the internal combustion engine includes a pressure sensor instead of the temperature sensor 20, and whether or not the intake pressure acquired from the pressure sensor exceeds a predetermined pressure (set pressure) corresponding to the set temperature T3. Based on this, the intake bypass valve 7 and the exhaust control valve 15 are controlled. Also by this, the ECU 22 can appropriately promote the defrosting of the intake control valve 6.

  Further, the ECU 22 controls opening / closing of the intake bypass valve 7 and the exhaust control valve 15 based on whether or not the intake temperature Tb or the intake pressure belongs to a predetermined set range instead of the set temperature T3 or the set pressure. May be executed. That is, the ECU 22 may give a constant width (value range) to the set temperature T3 and the set pressure. The set range is set in advance to an appropriate intake air temperature Tb or set pressure range based on experiments or the like. In this case, when the intake air temperature Tb is within the set temperature T3 in step S504 of FIG. 8, the ECU 22 advances the process to step S507 while maintaining the opening degree of the intake bypass valve 7, for example. Similarly, if the intake air temperature Tb is within the set temperature T3 in step S604 of FIG. 9, the ECU 22 advances the process to step S607 while maintaining the opening degree of the exhaust control valve 15, for example. Also by this, the ECU 22 can appropriately promote the defrosting of the intake control valve 6.

It is an example of the figure which shows schematic structure of the control apparatus of the internal combustion engine which concerns on each embodiment of this invention. It is a flowchart which shows the process of 1st Embodiment. It is a flowchart which shows the process of 2nd Embodiment. It is a flowchart which shows the process of 3rd Embodiment. It is a figure which shows the graph of the change of the intake temperature with time passage. It is a flowchart which shows the process of 4th Embodiment. It is a figure which shows the graph of the change of the intake temperature with time passage. It is a flowchart which shows the process of 5th Embodiment. It is a flowchart which shows the process of 6th Embodiment.

Explanation of symbols

2 Air cleaner 3 Intake passage 4, 5 Turbocharger 4a, 5a Compressor 4b, 5b Turbine 6 Intake control valve 7 Intake bypass valve 8 Internal combustion engine 10 Exhaust passage 11 EGR passage 14 EGR valve 15 Exhaust control valve 21 Water temperature sensor 22 ECU
23 Output device 31 Intake bypass passage

Claims (5)

A control device for an internal combustion engine comprising a first supercharger and a second supercharger,
An exhaust passage communicating with the turbine of the first supercharger and the turbine of the second supercharger;
An intake passage communicating with the compressor of the first supercharger and the compressor of the second supercharger;
A bypass passage for bypassing the downstream side of the compressor of the second supercharger and the upstream side of the compressor of the first supercharger;
An exhaust control valve that is provided on the exhaust passage and controls an exhaust passage;
An intake control valve provided on the intake passage for controlling a flow path of intake air;
A bypass valve provided on the bypass passage for controlling opening and closing of the bypass passage;
Freezing estimation means for estimating freezing of the exhaust control valve, the intake control valve, and the bypass valve at the start of the internal combustion engine;
Valve control means for performing opening control of the exhaust control valve by a predetermined opening so that exhaust is supplied to the turbine of the second supercharger when icing occurs in the intake control valve and the bypass valve;
A control device for an internal combustion engine, comprising:   When icing occurs in the intake control valve, the valve control means controls the exhaust control valve to be opened by a predetermined opening, and the intake temperature or intake pressure downstream of the compressor of the second supercharger is predetermined. The control device for an internal combustion engine according to claim 1, wherein the opening degree of the bypass valve is controlled so as to be within a set range.   The valve control means is configured to control the exhaust control valve so that an intake air temperature or an intake pressure downstream of a compressor of the second supercharger falls within a predetermined setting range when icing occurs in the intake control valve and the bypass valve. The control device for an internal combustion engine according to claim 1, wherein the opening degree of the engine is controlled.   When icing occurs in the intake control valve, the valve control means closes the bypass valve so that the intake air temperature or intake pressure downstream of the compressor of the second supercharger falls within a predetermined setting range. The control device for an internal combustion engine according to claim 1, wherein the opening degree of the exhaust control valve is controlled.   The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the first supercharger and the second supercharger are arranged in parallel to an intake passage and an exhaust passage.

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