JP4946782B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger, and more particularly to drive control of a variable valve mechanism when a required output changes.

A device (independent exhaust engine) comprising a first exhaust valve that opens and closes a first exhaust passage that communicates with a turbine, a second exhaust valve that opens and closes a second exhaust passage that does not pass through a turbine, and a catalyst downstream of an exhaust junction Is known (for example, see Patent Document 1).
According to this device, the exhaust energy can be guided to the turbine by opening the first exhaust valve. Furthermore, by opening the second exhaust valve, exhaust gas can be discharged while bypassing the turbine, and exhaust pumping loss can be reduced.

JP-A-10-89106 JP-A-6-173724 JP 2005-61325 A

Incidentally, in the high-speed operation region, the lift amount of the second exhaust valve is variably controlled according to the required output. In the medium speed operation region, the valve timing of the exhaust valve is retarded to earn work, and the second exhaust valve is stopped to increase the turbocharger response. Therefore, the required lift amount of the second exhaust valve may suddenly increase due to a change in the operation region. When the valve timing of the second exhaust valve is retarded and the lift amount control of the second exhaust valve is performed prior to the valve timing control, a valve stamp is generated in which the second exhaust valve contacts (interferences) with the piston. there's a possibility that.
Here, the response of the hydraulic variable valve timing mechanism is slower than the response of the electric or mechanical variable lift mechanism. Therefore, when the variable valve timing mechanism and the variable lift mechanism are driven simultaneously, there is a high possibility that the driving of the variable lift amount mechanism is completed first. If it does so, possibility that the said valve stamp will generate | occur | produce will become high.
On the other hand, in order to avoid the occurrence of a valve stamp, a method of increasing the valve recess on the piston top surface is conceivable. However, such an increase in valve recess has an adverse effect on the in-cylinder airflow particularly during lean combustion, leading to deterioration in combustion and fuel efficiency.

  The present invention has been made to solve the above-described problems. Even when there is a lift amount increase request and a valve timing advance request for the second exhaust valve that bypasses the supercharger, An object of the present invention is to provide a control device for an internal combustion engine capable of preventing the occurrence of valve stamps of two exhaust valves.

In order to achieve the above object, a first invention is a control device for an internal combustion engine with a supercharger,
A first exhaust valve for opening and closing a first exhaust passage provided with a turbine of the supercharger;
A second exhaust valve for opening and closing a second exhaust passage leading to the downstream of the turbine;
Lift amount variable means capable of changing the lift amount of the second exhaust valve;
A valve timing variable means capable of changing a valve timing of the first and second exhaust valves by changing a phase of an exhaust camshaft that drives the first exhaust valve and the second exhaust valve;
Control means for driving and controlling the lift amount varying means and the valve timing varying means,
The control means drives the variable valve timing means to a target value after driving the variable valve timing means to a target value when there is a request to increase the lift amount of the second exhaust valve and a request to advance the valve timing. Control is performed.

The second invention is the first invention, wherein
The control means is configured so that the lift amount of the second exhaust valve is a small lift amount that does not contact the second exhaust valve and the piston until the valve timing varying means is driven to a target value. The variable amount means is driven.

The third invention is the second invention, wherein
The control means drives the lift amount varying means so that the second exhaust valve becomes the small lift amount before starting the driving of the valve timing varying means.

Further, the fourth invention is the invention according to any one of the first to third inventions,
The control means performs the control when accelerating from a medium speed operation region where the second exhaust valve is stopped to a high speed operation region where the lift amount of the second exhaust valve is variably controlled. To do.

The fifth invention is the first invention, wherein
The control means performs the control when decelerating from a high-speed operation region where the lift amount of the second exhaust valve is variably controlled to a non-supercharging operation region.

The sixth invention is the first invention, wherein
A supercharging pressure acquisition means for acquiring a supercharging pressure of the intake system of the internal combustion engine;
When the control means accelerates from a non-supercharging operation area to a high-speed operation area where the lift amount of the second exhaust valve is variably controlled, the control means controls the lift amount variable means until the supercharging pressure reaches a predetermined value. The second exhaust valve is driven to stop, and the control is performed when the supercharging pressure exceeds a predetermined value.

  In the first invention, when there is a request for increasing the lift amount of the second exhaust valve and a request for advancement of the valve timing, after the valve timing variable means is driven to the target value, the lift amount variable means is driven to the target value. . Therefore, the lift amount of the second exhaust valve near the top dead center can be made smaller than when the lift amount varying means is driven to the target value before the valve timing varying means. Generation of a valve stamp can be prevented.

  In the second invention, the lift amount of the second exhaust valve is controlled to a small lift amount in which the second exhaust valve and the piston do not contact until the valve timing varying means is driven to the target value. Thereby, the overlap amount of the second exhaust valve and the intake valve is ensured while preventing the valve stamp of the second exhaust valve. As a result, the in-cylinder scavenging efficiency can be improved until the valve timing varying means is driven to the target value, so that a decrease in output during acceleration can be suppressed.

  In the third aspect of the invention, the second exhaust valve is controlled to a small lift amount before the driving of the valve timing varying means is started. As a result, the in-cylinder scavenging efficiency can be improved earlier than in the second aspect of the invention, so that a decrease in output during acceleration can be further suppressed.

  According to the fourth aspect of the invention, when accelerating from the medium speed operation region where the second exhaust valve is stopped to the high speed operation region where the lift amount of the second exhaust valve is variably controlled, the valve stamp of the second exhaust valve is set. Can be prevented.

  According to the fifth aspect, the valve stamp of the second exhaust valve can be prevented when decelerating from the high speed operation region in which the lift amount of the second exhaust valve is variably controlled to the non-supercharging operation region.

  In the sixth invention, when accelerating from the non-supercharging operation region to the high-speed operation region where the lift amount of the second exhaust valve is variably controlled, the second exhaust valve is stopped until the supercharging pressure reaches a predetermined value. It is done. Thereby, since the whole quantity of exhaust gas can be led to the turbine in the 1st exhaust passage, supercharging pressure can be raised in a short time. When the supercharging pressure exceeds a predetermined value, variable control of the lift amount of the second exhaust valve is performed. Therefore, the required output can be realized and the turbo response can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram showing a system configuration according to Embodiment 1 of the present invention. The system of the present embodiment is an independent exhaust engine having a supercharger (turbocharger).
The system shown in FIG. 1 includes an engine 1 having a plurality of cylinders 2. The pistons of the cylinders 2 are connected to a common crankshaft 4 via a crank mechanism. A crank angle sensor 5 that detects a crank angle CA is provided in the vicinity of the crankshaft 4.

  The engine 1 has an injector 6 corresponding to each cylinder 2. The injector 6 is configured to inject high pressure fuel directly into the cylinder 2. Each injector 6 is connected to a common delivery pipe 7. The delivery pipe 7 communicates with the fuel tank 9 via the fuel pump 8.

  The engine 1 has an intake port 10 corresponding to each cylinder 2. The intake port 10 is provided with a plurality of intake valves 11 (symbol “In” may be attached). The valve timing of the intake valve 11 can be changed by a variable valve timing mechanism (hereinafter also referred to as “InVVT”) 13. The variable valve timing mechanism 13 is configured to be able to change the phase of the intake camshaft 12 that drives the intake valve 11. As the variable valve timing mechanism 13, for example, a known hydraulic or mechanical variable valve timing mechanism can be used.

  Each intake port 10 is connected to an intake manifold 14. The intake manifold 14 is provided with a supercharging pressure sensor 15. The supercharging pressure sensor 15 is configured to measure a pressure of air supercharged by a compressor 24a (to be described later) (hereinafter referred to as “supercharging air”), that is, a supercharging pressure PIM.

  An intake passage 16 is connected to the intake manifold 14. A throttle valve 17 is provided in the intake passage 16. The throttle valve 17 is an electronically controlled valve that is driven by a throttle motor 18. The throttle valve 17 is driven based on the accelerator opening AA detected by the accelerator opening sensor 20. A throttle opening sensor 19 is provided in the vicinity of the throttle valve 17. The throttle opening sensor 19 is configured to detect the throttle opening TA. An intercooler 22 is provided upstream of the throttle valve 17. The intercooler 22 is configured to cool the supercharged air.

  A compressor 24 a of the supercharger 24 is provided upstream of the intercooler 22. The compressor 24a is connected to the turbine 24b via a connecting shaft (not shown). The turbine 24b is provided in a first exhaust passage 34 to be described later. The turbine 24b is rotationally driven by exhaust dynamic pressure (exhaust energy), whereby the compressor 24a is rotationally driven.

  An air flow meter 26 is provided upstream of the compressor 24a. The air flow meter 26 is configured to detect an intake air amount Ga. An air cleaner 28 is provided upstream of the air flow meter 26.

  Further, the engine 1 has a first exhaust valve 30A (symbol “Ex1” may be attached) and a second exhaust valve 30B (symbol “Ex2” may be attached) corresponding to each cylinder 2. have. The first exhaust valve 30A opens and closes the first exhaust passage 34 in which the turbine 24b is disposed. The turbine 24 b is configured to be rotationally driven by the exhaust dynamic pressure that flows through the first exhaust passage 34. The second exhaust valve 30B opens and closes the second exhaust passage 36 that does not pass through the turbine 24b and communicates downstream of the turbine 24b.

  The valve timings of these exhaust valves 30A and 30B can be changed by a variable valve timing mechanism (hereinafter also referred to as “ExVVT”) 31. The variable valve timing mechanism 31 is configured to be able to change the phase of the exhaust camshaft 29 that drives the exhaust valves 30A and 30B. As the variable valve timing mechanism 31, similarly to the variable valve timing mechanism 13, a known hydraulic or mechanical variable valve timing mechanism can be used.

  Further, the lift amount of the second exhaust valve 30 </ b> B can be changed by the variable lift amount mechanism 32. As the variable lift amount mechanism 32, for example, a known electric or mechanical variable lift amount mechanism can be used.

  A start-up catalyst (S / C) 42 is provided in the exhaust passage 40 downstream of the junction 38 of the first exhaust passage 34 and the second exhaust passage 36. An air-fuel ratio sensor 44 that detects the exhaust air-fuel ratio is provided upstream of the start-up catalyst 42 in the exhaust passage 40. A NOx catalyst 46 for purifying NOx in the exhaust gas is provided downstream of the starting catalyst 42.

The system according to the first embodiment includes an ECU (Electronic Control Unit) 60 that is a control device.
A crank angle sensor 5, a boost pressure sensor 15, a throttle opening sensor 19, an accelerator opening sensor 20, an air flow meter 26, an air-fuel ratio sensor 44, and the like are connected to the input side of the ECU 60. Further, an injector 6, a fuel pump 8, variable valve timing mechanisms 13 and 31, a throttle motor 18, a variable lift amount mechanism 32 and the like are connected to the output side of the ECU 60.
The ECU 60 calculates the engine speed NE based on the crank angle CA. Further, the ECU 60 calculates the engine torque TRQ based on the intake air amount Ga, the ignition timing, and the like.
The ECU 60 calculates the fuel injection amount to be injected into the cylinder based on the target air-fuel ratio and the intake air amount. Therefore, the engine 1 can perform lean combustion in addition to stoichiometric combustion.

[Features of Embodiment 1]
FIG. 2 is a diagram showing an operation region defined by the engine speed NE and the engine torque TRQ. As shown in FIG. 2, operating regions A to C are defined by the engine speed NE and the engine torque TRQ. FIG. 3 is a diagram showing valve opening characteristics in the operation region shown in FIG. Specifically, FIG. 3A shows the valve opening characteristics in the operation area A, FIG. 3B shows the valve opening characteristics in the operation area B, and FIG. 3C shows the valve opening characteristics in the operation area C. FIG.

In the operation region A where there is a high speed request, as shown in FIG. 3A, the lift amount of the second exhaust valve Ex2 (hereinafter referred to as “Ex lift amount”) is variably controlled according to the required output. As a result, the overlap amount between the second exhaust valve Ex2 and the intake valve In is controlled, and fresh air in the intake system is blown into the second exhaust passage 36, so that so-called in-cylinder scavenging efficiency can be improved. By this overlap amount control, the in-cylinder intake air amount can be increased, and a high output can be realized.
As shown in FIG. 3, the first exhaust valve Ex1 is opened before the second exhaust valve Ex2. This is because if the second exhaust valve Ex2 is opened first, the exhaust energy supplied to the turbine 24b becomes small and the boost pressure PIM cannot be raised.

  In the operation region B where the medium speed request is required, as shown in FIG. 3B, the first exhaust valve Ex1 operates at full lift, but the second exhaust valve Ex2 is closed. Thereby, since the exhaust gas total amount is supplied to the turbine 24b, the supercharging pressure PIM can be increased, and the turbo response can be improved. Further, in the operation region B, the valve timing (open / close valve timing) of the exhaust valves Ex1 and Ex2 is controlled to the retarded side as compared with the operation region A in order to earn work. As a result, the amount of overlap between the first exhaust valve Ex1 and the intake valve In is controlled, and fresh air in the intake system blows through the first exhaust passage 34. By this overlap amount control, the in-cylinder scavenging efficiency can be improved.

  The operation area C having a low speed request is a non-supercharging area. In this operation region C, as shown in FIG. 3C, both the first exhaust valve Ex1 and the second exhaust valve Ex2 operate at full lift. Thereby, the exhaust gas exchange in a cylinder can be made favorable.

  By the way, when there is an acceleration request (high output request) from the operation region B to the operation region A, the valve opening characteristic shown in FIG. 3 (B) is changed to the valve opening characteristic shown in FIG. 3 (A). The Rukoto. Therefore, it is necessary to advance the valve timing of the exhaust valves Ex1 and Ex2 and increase the Ex2 lift amount. Here, as described above, the valve timings of the exhaust valves Ex1, Ex2 in the operation region B are controlled to be retarded from the valve timings of the exhaust valves Ex1, Ex2 in the operation region A. Therefore, when the lift amount control of the second exhaust valve Ex2 is performed prior to the valve timing control of the exhaust valves Ex1 and Ex2, a “valve stamp” is generated in which the second exhaust valve Ex2 contacts (interferences) with the piston. there is a possibility. Further, the required lift amount of the second exhaust valve Ex2 in the operation region A is controlled based on the required output. For this reason, especially when the required lift amount of the second exhaust valve Ex2 is large, there is a high possibility that the valve stamp is generated.

  When there is a deceleration request (low output request) from the operation area A to the operation area C, the valve opening characteristic shown in FIG. 3A is changed to the valve opening characteristic shown in FIG. The Rukoto. Therefore, it is necessary to advance the valve timing of the exhaust valves Ex1 and Ex2, and to increase the Ex2 lift amount to the maximum lift amount. Also in this case, if the lift amount control of the second exhaust valve Ex2 is performed prior to the valve timing control of the exhaust valves Ex1 and Ex2, a valve stamp may occur. Furthermore, the overlap amount between the second exhaust valve Ex2 and the intake valve In becomes excessive, which may cause misfire due to an internal EGR amount abnormality. As a result, there is a possibility that drabbling abnormality or deterioration of the start-up catalyst 42 may be caused.

  In order to avoid the valve stamp, a method of increasing the valve recess on the piston top surface is conceivable. However, such an increase in the valve recess has an adverse effect on the in-cylinder airflow particularly during lean combustion, which may lead to deterioration in combustion and fuel efficiency.

Therefore, in the first embodiment, the valve timing control of the exhaust valves Ex1 and Ex2 and the lift amount control of the second exhaust valve Ex2 are performed in the following order without increasing the valve recess.
FIG. 4 shows the execution order of the valve timing control of the exhaust valves Ex1 and Ex2 and the lift amount control of the second exhaust valve Ex2 when there is an acceleration request from the operation region B to the operation region A in the first embodiment. FIG.
As shown in FIG. 4, before the second exhaust valve Ex2 is lifted (that is, before the Ex2 lift amount is increased), the valve timings of the exhaust valves Ex1 and Ex2 are advanced to a target value. After that, increase the Ex2 lift amount to the target value. When the Ex2 lift amount increases, the valve timing of the second exhaust valve Ex2 is advanced together with the valve timing of the first exhaust valve Ex1. For this reason, the Ex2 lift amount at the top dead center TDC can be reduced, and the occurrence of the valve stamp can be prevented.

FIG. 5 shows the execution order of the valve timing control of the exhaust valves Ex1 and Ex2 and the lift amount control of the second exhaust valve Ex2 when there is a deceleration request from the operation region A to the operation region C in the first embodiment. FIG.
As shown in FIG. 5, before increasing the Ex2 lift amount, the valve timings of the exhaust valves Ex1 and Ex2 are advanced to the target values. Then, increase Ex2 lift amount to the maximum lift amount. At this time, the valve timing of the second exhaust valve Ex2 is advanced to the target value together with the valve timing of the first exhaust valve Ex1. For this reason, the Ex2 lift amount at the top dead center TDC can be reduced, and the occurrence of the valve stamp can be prevented. Furthermore, since an excessive overlap amount between the second exhaust valve Ex2 and the intake valve In can be prevented, misfire due to an abnormal internal EGR amount can be prevented.

[Specific Processing in Embodiment 1]
FIG. 6 is a flowchart showing a routine executed by the ECU 60 in the first embodiment. This routine is started at predetermined intervals.
According to the routine shown in FIG. 6, first, engine operating parameters are acquired (step 100). In this step 100, for example, the accelerator opening AA and the engine speed NE are acquired. Thereafter, a required output (required torque) for the engine 1 is calculated based on the accelerator opening AA and the engine speed NE acquired in step 100 (step 102).

Next, based on the engine speed NE and the required output, the required lift amount of the second exhaust valve Ex2 (hereinafter referred to as “Ex2 required lift amount”), ExVVT retard amount (target value), and InVVT advance amount (target) Value) is calculated (step 104).
Since the first exhaust valve Ex1 is always opened with the maximum lift (see FIG. 3), the required lift amount of the first exhaust valve Ex1 is not calculated in this step 104.

  Thereafter, it is determined whether or not the Ex2 required lift amount calculated in step 104 is larger than the actual lift amount of the second exhaust valve Ex2 (hereinafter referred to as “Ex2 actual lift amount”) (step 106). If it is determined in step 106 that the Ex2 required lift amount is less than or equal to the Ex2 actual lift amount, it is determined that there is a request to decrease or maintain the Ex2 lift amount (step 108). In this case, the valve stamp is not generated even if the valve timing control is not performed prior to the lift amount control of the second exhaust valve Ex2. Therefore, the variable valve timing mechanism 31 is controlled (retard amount control) and the variable lift mechanism 32 is controlled (Ex2 lift amount control) (step 110). Thereafter, this routine is terminated.

  On the other hand, if it is determined in step 106 that the Ex2 required lift amount is larger than the Ex2 actual lift amount, it is determined that there is a request to increase the Ex2 lift amount (step 112). In this case, the control of the variable lift amount mechanism 32 (Ex2 lift amount control) is not performed immediately, but the Ex2 actual lift amount is first held (step 114). In other words, the Ex2 lift amount control is temporarily prohibited. Thereafter, control (retard amount control) of the variable valve timing mechanism 31 is performed (step 116).

  Then, it is determined whether or not the ExVVT retardation amount has reached the ExVVT retardation amount (target value) calculated in Step 104 (Step 118). In step 118, it is determined whether or not the valve timing control of the exhaust valves Ex1 and Ex2 is completed. If it is determined in step 118 that the ExVVT retard amount has not reached the ExVVT retard amount (target value), the valve timing control of the exhaust valves Ex1 and Ex2 is incomplete and the Ex2 lift amount control is performed. Then, it is determined that a valve stamp may occur. In this case, the process returns to step 114 above.

  On the other hand, if it is determined in step 118 that the ExVVT retardation amount has reached the ExVVT retardation amount (target value), it is determined that no valve stamp is generated even if the Ex2 lift amount is increased. In this case, Ex2 lift amount control is performed (step 120). Thereafter, this routine is terminated.

  As described above, according to the routine shown in FIG. 6, when there is a request to increase the Ex2 lift amount, the Ex2 actual lift amount is held and the ExVVT retardation amount control is performed. Then, after the ExVVT retardation amount control is completed, Ex2 lift amount control is performed. As a result, a situation in which the Ex2 lift amount increases near the top dead center TDC can be avoided, and the occurrence of the valve stamp of the second exhaust valve Ex2 can be prevented.

Incidentally, in the first embodiment, the Ex2 actual lift amount is maintained until the valve timing control is completed. However, until the valve timing control is completed, the stamp avoidance lift amount may be controlled to be smaller than the required lift amount (target value) as shown in FIG. FIG. 7 shows the valve timing control of the exhaust valves Ex1 and Ex2 and the lift amount control of the second exhaust valve Ex2 when there is an acceleration request from the operation region B to the operation region A in the modification of the first embodiment. It is a figure which shows an implementation order. As shown in FIG. 7, the valve timing of the exhaust valves Ex1 and Ex2 is advanced to the target value, and the Ex2 lift amount is controlled to the stamp avoidance lift amount. After the valve timing of the exhaust valves Ex1 and Ex2 is advanced to the target value, the lift amount of the second exhaust valve Ex2 is increased to the required lift amount.
FIG. 8 is a flowchart showing a routine executed by the ECU 60 in the present modification. The routine shown in FIG. 8 has step 115 instead of step 114 of the routine shown in FIG. That is, according to the routine shown in FIG. 8, when there is a request to increase the Ex2 lift amount, the Ex2 lift amount is controlled to the stamp avoidance lift amount (step 115). Thereafter, similarly to the routine shown in FIG. 6, control (retard amount control) of the variable valve timing mechanism 31 is performed (step 116), and the Ex2 lift amount is controlled to the required lift amount (step 120).
According to this modification, the Ex2 lift amount is controlled to the stamp avoidance lift amount until the valve timing control is completed. Therefore, the overlap amount of the second exhaust valve Ex2 and the intake valve In is ensured until the valve timing control is completed. Thereby, compared with the case where the second exhaust valve Ex2 is fully closed, the output can be increased by improving the in-cylinder scavenging efficiency. As a result, a transient output drop can be prevented.
Note that by controlling the Ex2 lift amount to the stamp avoidance lift amount before starting the valve timing control, the in-cylinder scavenging efficiency can be improved at an early stage, so that a transient output decrease can be further prevented. .

  In the first embodiment, the supercharger 24 is the “supercharger” in the first invention, the turbine 24b is the “turbine” in the first invention, and the first exhaust passage 34 is the first invention. The first exhaust valve 30A is the “first exhaust valve” in the first invention, the second exhaust passage 36 is the “second exhaust passage” in the first invention, The valve 30B is the “second exhaust valve” in the first invention, the variable lift amount mechanism 32 is the “lift amount varying means” in the first invention, and the exhaust cam shaft 29 is the “exhaust cam shaft” in the first invention. The variable valve timing mechanism 31 corresponds to the “valve timing variable means” in the first invention. Further, in the first embodiment, the ECU 60 executes the processing of steps 112 to 120, so that the “control unit” in the first invention executes the processing of step 115, thereby executing the second and third steps. The “control means” in the invention is realized respectively.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
The system of the second embodiment can be realized by causing the ECU 60 to execute a routine shown in FIG. 11 to be described later using the hardware configuration shown in FIG.

[Features of Embodiment 2]
In the first embodiment, the case where there is an acceleration request from the operation region B to the operation region A shown in FIG. 2 has been described.

  By the way, when there is an acceleration request from the operation region C shown in FIG. 2 to the operation region A, the valve opening characteristic shown in FIG. 3C is changed to the valve opening characteristic shown in FIG. Become. Therefore, according to normal control, the valve opening characteristic is changed as shown in FIG. FIG. 9 is a diagram illustrating normal control of valve opening characteristics when there is an acceleration request from the operation region C to the operation region A. FIG. As shown in FIG. 9, normally, the Ex2 lift amount is reduced and the valve timings of the exhaust valves Ex1 and Ex2 are retarded.

  However, if the control shown in FIG. 9 is performed in a state where the supercharging pressure PIM is low, the turbo response may be insufficient. Further, even if the overlap amount control between the exhaust valves Ex1 and Ex2 and the intake valve In is performed, the in-cylinder scavenging efficiency cannot be sufficiently improved and the required output may not be realized.

Therefore, in the second embodiment, when there is an acceleration request from the operation region C to the operation region A, when the supercharging pressure PIM is lower than the predetermined value PIMth, the valve opening characteristics shown in FIG. 10 are controlled. .
FIG. 10 shows the valve timing control of the exhaust valves Ex1, Ex2 when there is an acceleration request from the operation region C to the operation region A and the supercharging pressure PIM is lower than the predetermined value PIMth in the second embodiment. It is a figure which shows the execution order of lift amount control of 2 exhaust valve Ex2.
As shown in FIG. 10, before the variable lift amount control of the second exhaust valve Ex2 is performed, the state of the valve opening characteristic in the operation region B is interposed. That is, first, the valve opening characteristic in the operation region C is changed to the valve opening characteristic in the operation region B. Specifically, the second exhaust valve Ex2 is fully closed and the valve timings of the exhaust valves Ex1 and Ex2 are retarded. Here, in the engine 1 having the exhaust passages 34 and 36 as shown in FIG. 1, the transient response of the supercharging pressure PIM is maximized in the valve opening characteristic state in the operation region B. By temporarily controlling to such valve opening characteristics, the total amount of exhaust gas can be led to the turbine 24b, the boost pressure PIM can be increased in a short time, and the turbo response can be improved.

Thereafter, when the supercharging pressure PIM rises to a predetermined value PIMth or more, the valve opening characteristic in the operation area B is changed to the valve opening characteristic in the operation area A as shown in FIG. Specifically, as described in the first embodiment, after the valve timings of the exhaust valves Ex1 and Ex2 are advanced, the Ex2 lift amount is increased. Here, the predetermined value PIMth is a pressure sufficiently higher than the back pressure (see FIG. 12). By controlling the valve opening characteristics in the operation region C, the in-cylinder intake air amount can be increased. Furthermore, since the supercharging pressure PIM is sufficiently higher than the back pressure, the in-cylinder scavenging efficiency can be improved. Therefore, the required output can be realized.
Therefore, according to the second embodiment, the required output can be realized and the turbo response can be improved.

[Specific Processing in Second Embodiment]
FIG. 11 is a flowchart showing a routine executed by the ECU 60 in the second embodiment. This routine is started at predetermined intervals when the vehicle travels in the driving region C shown in FIG.
According to the routine shown in FIG. 11, first, engine operating parameters are acquired (step 101). In step 101, the accelerator opening AA, the engine speed NE, the supercharging pressure PIM, and the like are acquired. Based on the accelerator opening AA and the engine speed NE acquired in step 101, a required output (required torque) for the engine 1 is calculated (step 102). Thereafter, the Ex2 required lift amount, ExVVT retard amount (target value), and InVVT advance amount (target value) are calculated by the same method as the routine shown in FIG. 6 (step 104).

  Next, based on the engine speed NE and the required output, it is determined whether or not the operation region C (low speed region) shown in FIG. 2 is requested (step 122). If it is determined in step 122 that the operation region C is requested, it is determined that there is a request for maintaining the Ex2 lift amount (step 124). That is, it is determined that the Ex2 lift amount remains the maximum lift amount and that the Ex2 lift amount control is unnecessary. Therefore, this routine ends.

  On the other hand, if it is determined in step 122 that the operation region C is not requested, it is determined whether or not the operation region B (medium speed region) shown in FIG. 2 is requested (step 126). If it is determined in step 126 that the operation region B is requested, it is determined that there is a request to decrease the Ex2 lift amount (step 128). Then, Ex2 lift amount control for realizing this reduction request is performed (step 130). Thereafter, this routine is terminated.

  If it is determined in step 128 that the operation area B is not requested, that is, if the operation area A (high speed area) shown in FIG. 2 is requested, the Ex2 lift amount can be changed according to the requested output. It is determined that there is a request (step 132). Thereafter, it is determined whether or not the actual boost pressure PIM acquired in step 101 is lower than a predetermined value PIMth (step 134). The predetermined pressure PIMth used for the discrimination process in step 134 is read with reference to the map shown in FIG. FIG. 12 is a diagram showing a map referred to in the routine shown in FIG. In FIG. 12, the alternate long and short dash line indicates the atmospheric pressure, the broken line indicates the back pressure, and the solid line indicates the predetermined pressure PIM. As shown in FIG. 12, a predetermined value PIMth that is sufficiently higher than the back pressure is defined in relation to the engine speed NE. By referring to the map in step 134, a predetermined value PIM that provides sufficient in-cylinder scavenging efficiency is read out in correspondence with the engine speed NE.

  If it is determined in step 134 that the actual boost pressure PIM is equal to or greater than the predetermined value PIMth, normal Ex2 lift amount control shown in FIG. 9 is performed (step 130). That is, the Ex2 lift amount is controlled from the maximum lift amount to the Ex2 required lift amount calculated in step 104 above.

  On the other hand, if it is determined in step 134 that the actual boost pressure PIM is lower than the predetermined value PIMth, Ex2 lift amount transient control shown in FIG. 10 is performed (step 136). In step 136, the second exhaust valve Ex2 is fully closed. Further, the valve timings of the exhaust valves Ex1, Ex2 are retarded. As a result, since the entire amount of exhaust gas is supplied to the turbine 24b, the supercharging pressure PIM increases in a short period of time. Thereafter, this routine is terminated.

Thereafter, this routine is started, and if it is determined in step 134 that the actual boost pressure PIM is equal to or greater than the predetermined value PIMth, the Ex2 lift amount is controlled to the Ex2 required lift amount calculated in step 104 above. (Step 138). That is, Ex2 lift amount control according to the required output calculated in step 102 is performed.
At this time, it is preferable to execute the Ex2 lift amount control after controlling the valve timings of the exhaust valves Ex1 and Ex2 to the target values as in steps 114 to 120 of the routine shown in FIG. Further, as in step 115 of the routine shown in FIG. 8, the Ex2 lift amount can be controlled to the stamp avoidance lift amount until the valve timing of the exhaust valves Ex1 and Ex2 is controlled to the target value. Thereby, generation | occurrence | production of the valve stamp of 2nd exhaust valve Ex2 can be prevented.
After step 138, this routine is terminated.

  As described above, according to the routine shown in FIG. 11, if there is a high output request (operation region A request) during traveling in the non-supercharging operation region C, is the actual supercharging pressure PIM lower than the predetermined value PIMth? Determine whether or not. When the actual boost pressure PIM is lower than the predetermined value PIMth, the second exhaust valve Ex2 is fully closed until the actual boost pressure PIM becomes equal to or higher than the predetermined value PIMth. Once the second exhaust valve Ex2 is fully closed, the transient response of the supercharging pressure PIM is maximized, and the supercharging pressure PIM can be increased in a short period of time. When the actual boost pressure PIM becomes equal to or greater than the predetermined value PIMth, variable control of the Ex2 lift amount according to the required output is performed. As a result, the in-cylinder scavenging efficiency can be improved, and the output can be increased. Therefore, the required output can be realized and the turbo response can be improved.

  In the second embodiment, the ECU 60 executes the process of step 101, so that the “supercharging pressure acquisition means” in the sixth invention executes the processes of steps 132 to 138. The “control means” in the invention is realized respectively.

It is a figure which shows the system configuration | structure by Embodiment 1 of this invention. It is a figure which shows the driving | running area | region prescribed | regulated by engine speed NE and engine torque TRQ. It is a figure which shows the valve opening characteristic in the operation area | region shown in FIG. The figure which shows the execution order of valve timing control of exhaust valve Ex1, Ex2 and lift amount control of 2nd exhaust valve Ex2 when there exists an acceleration request | requirement from the operation area B to the operation area A in Embodiment 1 of this invention. It is. The figure which shows the execution order of valve timing control of exhaust valve Ex1, Ex2 and lift amount control of 2nd exhaust valve Ex2 when there exists a deceleration request | requirement from the driving | operation area | region A to the driving | operation area | region C in Embodiment 1 of this invention. It is. 5 is a flowchart showing a routine that is executed by the ECU 60 in the first embodiment of the present invention. In the modification of the first embodiment of the present invention, the execution order of the valve timing control of the exhaust valves Ex1, Ex2 and the lift amount control of the second exhaust valve Ex2 when there is an acceleration request from the operation region B to the operation region A FIG. 7 is a flowchart showing a routine executed by ECU 60 in a modification of the first embodiment of the present invention. It is a figure which shows control of the normal valve opening characteristic when the acceleration request | requirement from the driving | operation area | region C to the driving | operation area | region A exists. In Embodiment 2 of the present invention, there is a request for acceleration from the operation region C to the operation region A, the valve timing control of the exhaust valves Ex1, Ex2 when the supercharging pressure PIM is lower than the predetermined value PIMth, and the second exhaust It is a figure which shows the execution order of lift amount control of valve Ex2. In Embodiment 2 of this invention, it is a flowchart which shows the routine which ECU60 performs. It is a figure which shows the map referred by the routine shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 11 Intake valve 13 Variable valve timing mechanism 24 Supercharger 24b Turbine 29 Exhaust cam shaft 30A 1st exhaust valve 30B 2nd exhaust valve 31 Variable valve timing mechanism 32 Variable lift amount mechanism 34 1st exhaust path 36 2nd exhaust path 42 Catalyst at start-up 60 ECU

Claims (3)

A control device for an internal combustion engine with a supercharger,
A first exhaust valve for opening and closing a first exhaust passage provided with a turbine of the supercharger;
A second exhaust valve for opening and closing a second exhaust passage leading to the downstream of the turbine;
Lift amount variable means capable of changing the lift amount of the second exhaust valve;
A valve timing variable means capable of changing a valve timing of the first and second exhaust valves by changing a phase of an exhaust camshaft that drives the first exhaust valve and the second exhaust valve;
Control means for driving and controlling the lift amount varying means and the valve timing varying means ;
Supercharging pressure acquisition means for acquiring the supercharging pressure of the intake system of the internal combustion engine ,
The control means is a case of accelerating from a non-supercharging operation region to a high-speed operation region in which the lift amount of the second exhaust valve is variably controlled, and the second exhaust valve lift amount increase request and valve timing advance angle When requested, the lift amount variable means is driven to stop the second exhaust valve until the supercharging pressure reaches a predetermined value, and when the supercharging pressure exceeds a predetermined value, the valve timing is increased. A control apparatus for an internal combustion engine, wherein after the variable means is driven to a target value, control is performed to drive the lift amount variable means to the target value. The control apparatus for an internal combustion engine according to claim 1,
The control means is configured so that the lift amount of the second exhaust valve is a small lift amount that does not contact the second exhaust valve and the piston until the valve timing varying means is driven to a target value. A control device for an internal combustion engine, which drives a variable amount means. The control apparatus for an internal combustion engine according to claim 2,
The control device for the internal combustion engine, wherein the control means drives the lift amount varying means so that the second exhaust valve becomes the small lift amount before starting the driving of the valve timing varying means. .

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