JP4893514B2 - Control device for an internal combustion engine with a supercharger - Google Patents

Description

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

  Conventionally, for example, Patent Document 1 discloses an internal combustion engine with a supercharger including a variable valve operating device. In this conventional internal combustion engine, when accelerating, the opening timing of the exhaust valve is advanced and then the opening and closing timing of the intake valve is controlled to reduce the valve overlap period, thereby improving the responsiveness of the turbocharger. It is increasing.

JP 2003-3871 A JP 10-31801 A Japanese Patent Laid-Open No. 2-119641

  By the way, in an internal combustion engine with a supercharger, when a deceleration request is issued in a state where the pressure in the intake passage is higher than the pressure in the exhaust passage due to supercharging, a valve overlap period is provided. In some cases, blow-in of intake air from the intake passage to the exhaust passage may occur. When a large amount of oxygen is supplied to the catalyst due to such a large amount of intake air blown, there is a concern about deterioration of exhaust emission or catalyst deterioration.

  The present invention has been made to solve the above-described problems, and in an internal combustion engine with a supercharger capable of adjusting the valve overlap period, at the time of deceleration from a state where the valve overlap period exists, It is an object of the present invention to provide a control device for an internal combustion engine with a supercharger capable of satisfactorily preventing deterioration of exhaust emission and catalyst deterioration due to intake air blow-through.

A first invention is a supercharger that supercharges intake air;
An intake variable valve mechanism that makes at least the opening timing of the intake valve variable;
An exhaust variable valve mechanism for varying at least the closing timing of the exhaust valve;
An overlap period control means for adjusting a valve overlap period in which the intake valve opening period and the exhaust valve opening period overlap by controlling the opening timing of the intake valve and the closing timing of the exhaust valve;
A catalyst disposed in the exhaust passage;
Catalyst information acquisition means for acquiring information relating to the internal state of the catalyst,
When changing the valve overlap period when decelerating from a state in which the valve overlap period exists, the overlap period control means controls the opening timing of the intake valve and the exhaust gas according to the internal state of the catalyst. Changing the control sequence of the valve closing timing control or changing the control speed of the intake valve opening timing and the exhaust valve closing timing control ;
The overlap period control means changes the operation sequence or reduces the control speed when decelerating from the state where the supercharging pressure is equal to or greater than a predetermined value of positive pressure and the valve overlap period exists. It is characterized by making different .

In a second aspect based on the first aspect , the catalyst information acquisition means is means for acquiring oxygen concentration information inside the catalyst,
When the oxygen concentration inside the catalyst is equal to or greater than a predetermined value, the overlap period control means first advances the closing timing of the exhaust valve to the target value after deceleration, and then opens the intake valve. The timing is retarded to the target value after deceleration.

In a third aspect based on the first aspect , the catalyst information acquisition means is means for acquiring oxygen concentration information inside the catalyst.
When the oxygen concentration inside the catalyst is less than a predetermined value, the overlap period control means delays the opening timing of the intake valve to the target value after deceleration before closing the exhaust valve. The timing is advanced to the target value after deceleration.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the oxygen concentration acquisition unit is an oxygen concentration sensor disposed in an exhaust passage on the downstream side of the catalyst.

Further, in a fifth aspect based on the first aspect , the catalyst information acquisition means is means for acquiring temperature information of the catalyst,
When the temperature of the catalyst is equal to or higher than a predetermined value, the overlap period control means decelerates the opening timing of the intake valve after advancing the closing timing of the exhaust valve to the target value after deceleration first. It is characterized by retarding to a later target value.

In a sixth aspect based on the first aspect , the catalyst information acquisition means is means for acquiring oxygen storage amount information of the catalyst,
When the oxygen storage amount of the catalyst is equal to or greater than a predetermined value, the overlap period control means advances the closing timing of the exhaust valve to the target value after deceleration first, and then opens the intake valve. Is retarded to the target value after deceleration.

Further, in a seventh aspect based on the first aspect , the catalyst information acquisition means is means for acquiring oxygen storage amount information of the catalyst,
When the oxygen storage amount of the catalyst is less than a predetermined value, the overlap period control means delays the opening timing of the intake valve to the target value after deceleration before closing the exhaust valve. Is advanced to the target value after deceleration.

According to the first aspect of the invention, the valve overlap period during the deceleration process is given a weight to the valve overlap period existing in the exhaust stroke or the valve existing in the intake stroke according to the internal state of the catalyst. It is possible to give weight to the overlap period. If the valve overlap period existing during the exhaust stroke is given a weight, the intake air blow-off to the exhaust side can be made difficult to occur, and the valve overlap period existing during the intake stroke is weighted. If it has, it can make it easy to produce the blow-in of the intake air to the exhaust side. For this reason, according to the present invention, it is possible to satisfactorily prevent deterioration of exhaust emission and catalyst deterioration due to intake air blow-off during deceleration from a state in which a valve overlap period exists. Further, according to the present invention, the deceleration from the state in which the valve overlap period exists in a situation where the intake pressure blows into the exhaust side due to the supercharging pressure being equal to or greater than the predetermined value of the positive pressure. Sometimes, it is possible to satisfactorily prevent the deterioration of exhaust emission and the deterioration of the catalyst due to intake air blow-through.

According to the second aspect of the present invention, during deceleration when the oxygen concentration inside the catalyst is equal to or higher than a predetermined value, the pressure in the intake passage is present in the exhaust stroke at the early stage of deceleration when the pressure is high. By giving weighting to the valve overlap period, it is possible to create a situation in which intake air blow-out to the exhaust side hardly occurs. For this reason, the supply of oxygen to the catalyst can be restricted, and the oxygen storage amount OSC of the catalyst can be reduced to an appropriate amount. Thereby, deterioration of exhaust emission can be satisfactorily prevented.

According to the third aspect of the present invention, during deceleration when the oxygen concentration inside the catalyst is less than a predetermined value, the pressure in the intake passage is present during the intake stroke at the beginning of deceleration when the pressure is high. By giving a weight to the valve overlap period, it is possible to create a situation in which intake air blowout to the exhaust side is likely to occur. For this reason, sufficient oxygen can be supplied to the catalyst, and the oxygen storage amount OSC of the catalyst can be increased to an appropriate amount. Thereby, deterioration of exhaust emission can be satisfactorily prevented.

According to the fourth aspect of the present invention, it is possible to satisfactorily control the blow-in of the intake air to the exhaust side during deceleration according to the oxygen concentration information inside the catalyst based on the signal of the oxygen concentration sensor. The occlusion amount OSC can be appropriately managed.

According to the fifth aspect of the present invention, the valve overlap existing in the exhaust stroke at the initial stage of deceleration when the pressure in the intake passage is high during deceleration when the temperature of the catalyst is equal to or higher than a predetermined value. By giving a weight to the period, it is possible to create a situation in which the intake air does not easily blow through to the exhaust side. For this reason, it becomes possible to suppress well that the catalyst in a high temperature state is exposed to a large amount of oxygen. Thereby, it is possible to satisfactorily prevent the catalyst from deteriorating during deceleration from the supercharged state.

According to the sixth aspect of the present invention, the valve existing in the exhaust stroke at the initial stage of deceleration when the pressure in the intake passage is high during deceleration when the oxygen storage amount of the catalyst is equal to or greater than a predetermined value. By giving weighting to the overlap period, it is possible to create a situation in which intake air blow-out to the exhaust side hardly occurs. For this reason, the supply of oxygen to the catalyst can be restricted, and the oxygen storage amount OSC of the catalyst can be reduced to an appropriate amount. Thereby, deterioration of exhaust emission can be satisfactorily prevented.

According to the seventh aspect of the present invention, the valve existing in the intake stroke at the beginning of deceleration when the pressure in the intake passage is high during deceleration when the oxygen storage amount of the catalyst is less than the predetermined value. By giving weighting to the overlap period, it is possible to create a situation in which intake air blowout to the exhaust side is likely to occur. For this reason, sufficient oxygen can be supplied to the catalyst, and the oxygen storage amount OSC of the catalyst can be increased to an appropriate amount. Thereby, deterioration of exhaust emission can be satisfactorily prevented.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a schematic configuration diagram for explaining a system configuration according to the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine 10. The internal combustion engine 10 is a multi-cylinder engine having a plurality of cylinders, and FIG. 1 shows a cross section of one of the cylinders.

  The intake system of the internal combustion engine 10 includes an intake passage 12. Air is taken into the intake passage 12 from the atmosphere and is distributed to the combustion chamber 14 of each cylinder. An air cleaner 16 is attached to the inlet of the intake passage 12. An air flow meter 18 that outputs a signal corresponding to the flow rate of air taken into the intake passage 12 is provided in the vicinity of the downstream side of the air cleaner 16.

  A turbocharger 20 with an electric motor is provided downstream of the air flow meter 18. The turbocharger 20 includes a compressor 20a, a turbine 20b, and an electric motor 22 disposed between the compressor 20a and the turbine 20b. The compressor 20a and the turbine 20b are integrally connected by a connecting shaft, and the compressor 20a is rotationally driven by the exhaust energy of the exhaust gas input to the turbine 20b. The connecting shaft is also a rotor of the electric motor 22, and the compressor 20 a can be forcibly driven by operating the electric motor 22.

  An intercooler 24 for cooling the compressed air is provided downstream of the compressor 20a. A throttle valve 26 is disposed downstream of the intercooler 24. The throttle valve 26 is an electronically controlled valve that is driven by a throttle motor based on the accelerator opening. A throttle position sensor 28 for detecting the throttle opening degree TA is disposed in the vicinity of the throttle valve 26.

  An intake air temperature sensor 30 for detecting the temperature of the intake air cooled by the intercooler 24 is arranged in the middle of the intake passage 12 from the intercooler 24 to the throttle valve 26, and downstream of the compressor 20a. An upstream pressure sensor 32 for detecting the intake passage internal pressure (supercharging pressure) upstream of the throttle valve 26 is disposed. A surge tank 34 is provided downstream of the throttle valve 26. The surge tank 34 is provided with a downstream pressure sensor 36 for detecting the intake passage internal pressure (intake pressure) downstream of the throttle valve 26.

  In addition, a port injection valve 38 for injecting fuel is disposed in the intake port of each cylinder, which is the end of the intake passage 12 on the combustion chamber 14 side. The fuel pumped from the fuel tank 40 by the fuel pump 42 is supplied to the port injection valve 38. The internal combustion engine 10 also includes an in-cylinder injection valve 44 for directly injecting fuel into the combustion chamber 14. The in-cylinder injection valve 44 is supplied with fuel further increased in pressure by the high-pressure fuel pump 46.

  The intake passage 12 is provided with a bypass passage 48 for bypassing the compressor 20a. More specifically, the bypass passage 48 is provided so that the air cleaner 16 and the intercooler 24 communicate with each other, and an air bypass valve 50 that controls the amount of air passing through the bypass passage 48 is disposed in the middle of the bypass passage 48. Has been.

  The exhaust system of the internal combustion engine 10 includes an exhaust passage 52. In the exhaust passage 52, the turbine 20b of the turbocharger 20 described above is disposed. The exhaust passage 52 is connected to an exhaust bypass passage 54 that bypasses the turbine 20b and connects the inlet side and the outlet side of the turbine 20b. A wastegate valve (WGV) 56 is disposed in the middle of the exhaust bypass passage 54.

  Further, an upstream catalyst (SC) 58 and a downstream catalyst (UF) 60 for purifying exhaust gas are arranged in series downstream of the turbine 20b. An air-fuel ratio sensor 62 for detecting the exhaust air-fuel ratio at that position is disposed upstream of the upstream catalyst 58. Further, an oxygen sensor 64 that generates a signal corresponding to whether the air-fuel ratio at that position is rich or lean is disposed between the upstream catalyst 58 and the downstream catalyst 60.

  Further, the system shown in FIG. 1 includes an intake variable valve mechanism 70 and an exhaust variable valve mechanism 72 for driving the intake valve 66 and the exhaust valve 68 of each cylinder, respectively. These variable valve mechanisms 70 and 72 are each provided with a VVT mechanism for controlling the opening / closing timing of the intake valve and the exhaust valve. According to such variable valve mechanisms 70 and 72, a desired valve overlap period can be obtained by appropriately controlling the advance amount of the intake valve 66 and the retard amount of the exhaust valve 68.

  The control system of the internal combustion engine 10 includes an ECU (Electronic Control Unit) 80. In addition to the various sensors described above, the ECU 80 is connected to a crank angle sensor 82 for detecting the engine speed and the various actuators described above. The ECU 80 can control the operating state of the internal combustion engine 10 based on those sensor outputs.

[Control of intake and exhaust valves when decelerating from a supercharged state]
FIG. 2 is a diagram for explaining the relationship between the motion of the piston 84 and the amount of intake air blown. More specifically, FIG. 2 (A) shows the operation during the intake stroke. In the intake stroke, since the piston 84 is lowered, the inside of the cylinder becomes a negative pressure source. As a result, the pressurized intake air during supercharging easily enters the cylinder. Therefore, as shown in FIG. 2A, when the intake and exhaust valves 66 and 68 are controlled so that the valve overlap period exists during the intake stroke during supercharging, the intake air in the pressurized state is not It becomes easy to escape directly to the exhaust side.

  On the other hand, FIG. 2B shows the operation during the exhaust stroke. In the exhaust stroke, the piston 84 is raised, so that the inside of the cylinder is pressurized as compared with the intake stroke. As a result, it is difficult for the intake air pressurized during supercharging to enter the cylinder. Therefore, as shown in FIG. 2B, even when the intake and exhaust valves 66 and 68 are controlled so that a valve overlap period exists during the exhaust stroke during supercharging, the pressurized state is maintained. Some intake air is difficult to escape directly to the exhaust side.

  For the above reasons, when there is a valve overlap period during the intake stroke, intake air blows out easily to the exhaust side, and conversely, there is a valve overlap period during the exhaust stroke. If it is, the intake air does not easily blow through to the exhaust side.

  By the way, when the amount of the blow-in of the intake air increases as described above, when an amount of oxygen exceeding the allowable value of the oxygen storage amount OSC of the catalyst 58 and the like is supplied to the catalysts 58 and 60, NOx is reduced. There is a concern that the exhaust emission cannot be reduced and exhaust emission deteriorates. On the other hand, if the valve overlap period is set to be less than an appropriate value according to the operating state in order to suppress the inflow of oxygen into the catalyst 58 or the like, the torque reduction of the internal combustion engine 10 becomes large, and the driver of the internal combustion engine 10 There is concern about the deterioration of

  Therefore, in the present embodiment, when the valve overlap period is reduced at the time of deceleration from the supercharging state in which the valve overlap period exists, as described with reference to FIGS. 3 to 6 below, the upstream catalyst In accordance with the output signal of the oxygen sensor 64 disposed downstream of 58 (that is, according to the oxygen concentration inside the upstream catalyst 58), the operation sequence of the retard control of the intake valve 66 and the advance control of the exhaust valve 68 is determined. Was changed. In the present specification, the state in which the pressure in the intake passage 12 is higher than the pressure in the exhaust passage 52 because the supercharging pressure is positive is referred to as “supercharging state”. It is called.

  FIG. 3 is a diagram showing the retard amount of the exhaust valve 68 and the advance amount of the intake valve 66 in relation to the shaft torque of the internal combustion engine 10. In FIG. 3, the retard amount of the exhaust valve 68 (hereinafter sometimes referred to as “exhaust VVT retard amount”) and the advance amount of the intake valve 66 (hereinafter referred to as “intake VVT advance amount”). Both zero points of) indicate intake top dead center. Therefore, the region on the left side of the straight line (exhaust VVT retard angle = intake VVT advance angle relationship) shown in FIG. 3 is an area where the exhaust VVT retard amount is larger than the intake VVT advance amount. Therefore, it can be said that the valve overlap period existing in the intake stroke is a weighted region than the valve overlap period existing in the exhaust stroke. Further, in FIG. 3, the region on the right side of the straight line is a region in which the intake VVT advance amount is larger than the exhaust VVT retard amount, so that a valve overlap period existing in the exhaust stroke exists in the intake stroke. It can be said that the region is weighted more than the valve overlap period.

  As shown in FIG. 3, the valve overlap period is basically set so as to increase as the shaft torque (load) increases. Therefore, for example, in the case where the operating state transitions from the point marked “current value” in FIG. 3 to the point marked “target value” on the low load (low torque) side, When a deceleration request (request for reducing torque) is issued, the valve overlap period is shortened so as to obtain an appropriate value in the operation state after the deceleration request.

  When reducing the valve overlap period during deceleration from the supercharged state as described above, the system of the present embodiment sets the intake VVT advance amount so that the valve overlap period becomes the target value without any consideration. Rather than controlling the exhaust VVT retard amount, the operation sequence of the control of the intake VVT advance amount and the exhaust VVT retard amount is changed according to the signal of the oxygen sensor 64. More specifically, when the signal of the oxygen sensor 64 indicates a rich output, as shown in FIG. 3, first, the intake VVT advance amount is controlled until it reaches its target value, and then the exhaust VVT delay is controlled. The angular amount is controlled until the target value is reached.

  FIG. 4 is a diagram for explaining how to adjust the valve timing of the intake and exhaust valves 66 and the like when a deceleration request is issued from the supercharged state when the signal of the oxygen sensor 64 indicates a rich output. More specifically, FIG. 4A shows the valve overlap period (corresponding to the current value in FIG. 3) at the time when the deceleration request is issued. In this embodiment, when the signal of the oxygen sensor 64 at the time shown in FIG. 4A indicates a rich output, that is, it can be determined that the oxygen concentration in the upstream catalyst 58 is low and oxygen is insufficient. In this case, as shown in FIG. 4B, the intake VVT advance amount is reduced first (ie, the opening timing of the intake valve 66 is retarded) while leaving the exhaust VVT retard amount as it is.

  Then, after the intake VVT advance amount reaches its final (after deceleration) target value, as shown in FIG. 4C, the exhaust VVT retard amount is reduced (ie, the closing timing of the exhaust valve 68). The valve overlap period is adjusted so that the target value in the operating state after the deceleration request is obtained.

  FIG. 5 is a time chart showing the operation in the case shown in FIG. As shown in FIG. 5 (A), when the deceleration request from the supercharging state is issued and the execution flag for determining whether or not the control according to this embodiment is necessary is turned ON, FIG. As shown in (B), the valve overlap period is decreased so as to become a suitable value in the operation state after the deceleration request. In this case, according to the method shown in FIG. 3 and FIG. 4, as shown in FIG. 5C, first, the intake VVT advance amount is retarded toward the target value. After the intake VVT advance amount reaches the target value, the exhaust VVT retard amount is advanced toward the target value as shown in FIG.

  According to such control, in the initial stage of deceleration where the pressure in the intake passage 12 is high, the valve overlap period existing during the intake stroke is weighted (that is, the valve overlap existing during the intake stroke). As described above with reference to FIG. 2, it is possible to create a situation in which intake air is easily blown out. Thus, sufficient oxygen can be supplied to the upstream catalyst 58 and the like. Thus, the oxygen storage amount OSC of the upstream catalyst 58 and the like can be increased to an appropriate amount.

  On the other hand, when the signal of the oxygen sensor 64 indicates a lean output, as shown in FIG. 3, first, the exhaust VVT retard amount is controlled until it reaches its target value, and then the intake VVT advance amount is set to that value. Control is performed until the target value is reached.

  FIG. 6 is a diagram for explaining how to adjust the valve timing of the intake / exhaust valve 66 and the like when a deceleration request is issued from the supercharging state when the signal of the oxygen sensor 64 indicates a lean output. More specifically, FIG. 6A also shows the valve overlap period (corresponding to the current value in FIG. 3) at the time when the deceleration request is issued. In the present embodiment, when the signal of the oxygen sensor 64 at the time shown in FIG. 6A indicates a lean output, that is, when it can be determined that the oxygen concentration inside the upstream catalyst 58 is high and oxygen is excessive. As shown in FIG. 6B, the intake VVT advance amount is left as it is, and the exhaust VVT retard amount is reduced first (that is, the closing timing of the exhaust valve 68 is advanced).

  Then, after the exhaust VVT retard amount reaches the final target value (after deceleration), the intake VVT advance amount is decreased (that is, when the intake valve 66 is opened), as shown in FIG. The valve overlap period is adjusted so that the target value in the operation state after the deceleration request is obtained. The time chart corresponding to the case shown in FIG. 6 corresponds to that obtained by reversing the operation order of the intake VVT advance amount and the exhaust VVT retard amount in FIG. 5 above. Detailed description thereof will be omitted.

  According to such control, in the initial stage of deceleration where the pressure in the intake passage 12 is high, the valve overlap period existing during the exhaust stroke is weighted (the valve overlap period existing during the exhaust stroke is reduced). As described above with reference to FIG. 2, it is possible to create a situation in which intake air does not easily blow through, thereby restricting the supply of oxygen to the upstream catalyst 58 and the like. Thus, the oxygen storage amount OSC of the upstream catalyst 58 and the like can be reduced to an appropriate amount.

  According to the control of the present embodiment described above, the oxygen storage amount OSC of the upstream catalyst 58 and the like is appropriately managed at the time of deceleration from the supercharging state in which intake air blow-off is a concern, and exhaust emission deterioration or internal combustion It is possible to suitably prevent the drivability of the engine 10 from deteriorating.

Next, specific processing in Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 7 is a flowchart of a main routine executed by the ECU 80 in the first embodiment to realize the above function. It is assumed that the routine shown in FIG. 7 is started when it is detected that the accelerator pedal is closed during the operation of the internal combustion engine 10 (a request to reduce the torque of the internal combustion engine 10 has been issued). That is, this routine is started when the internal combustion engine 10 enters a transient operation state.

  In the routine shown in FIG. 7, it is first determined whether or not the intake pipe pressure (the pressure on the downstream side of the throttle valve 26 detected by the downstream pressure sensor 36) is higher than a predetermined value (step 100). The predetermined value in this step 100 is used to determine whether or not intake air blowout occurs, that is, whether or not the pressure on the intake passage 12 side is higher than the pressure on the exhaust passage 52 side. As a value, it is a value obtained in advance by experiments or the like.

  When it is determined in step 100 that the intake pipe pressure is higher than the predetermined value, that is, it can be determined that intake air blow-through occurs in a situation where a deceleration request is issued to the internal combustion engine 10. Next, it is determined whether the signal of the oxygen sensor 64 indicates a rich output or a lean output (step 102).

  As a result, if it is determined that the current signal from the oxygen sensor 64 indicates a lean output, the valve overlap period existing during the exhaust stroke is weighted, and after a deceleration request (after a low load transition) The valve overlap period is reduced so as to be the target value (step 104).

FIG. 8 is a flowchart of a subroutine showing specific processing of step 104 in FIG. This routine is executed every predetermined control cycle.
In the routine shown in FIG. 8, first, the target overlap period (amount) OV (k) during the deceleration process is the same as the target overlap period OV (k−1) at the previous routine execution and the current routine execution. It is calculated as a difference from the decrease amount dOV of the overlap period (step 200). More specifically, the final target overlap period in the operating state after deceleration is determined based on the closing amount of the accelerator pedal and the current engine speed. In this step 200, the target overlap period OV (k) is obtained by subtracting the decrease dOV obtained in accordance with a separately defined relationship from the target overlap period OV (k-1) at the previous routine execution. It is gradually updated (decreased) toward the final target overlap period.

  For example, in the example shown in FIG. 3, the target overlap period “current value” at the time of the deceleration request includes the intake VVT advance amount of about 22 ° CA and the exhaust VVT retard amount of about 28 ° CA. About 50 ° CA. The target overlap period is determined from such a “current value” to a “target value” (0 ° CA of the intake VVT advance amount and the exhaust VVT delay angle) that is the final target overlap period in the operating state after deceleration. The amount is decreased by the amount of decrease dOV in each predetermined control cycle toward the amount of 10 ° CA in total of 108 ° CA.

  Next, whether or not the final target value of the exhaust VVT retardation amount is smaller than the transient target value EXVTref (k) of the exhaust VVT retardation amount, that is, the transient target value EXVTref (k) reaches the final target value. It is determined whether or not it has been performed (step 202). The final target value of the exhaust VVT retardation amount in this step 202 is the exhaust VVT retardation amount in the operating state after deceleration, and is 10 ° CA in the example shown in FIG. Further, the transient target value EXVTref (k) of the exhaust VVT retardation amount referred to in this step 202 is gradually changed every predetermined control period as the target overlap period OV (k) in step 200 decreases. This is the target value of the exhaust VVT retardation amount.

  If it is determined in step 202 that exhaust VVT final target value <exhaust VVT transient target value EXVTref (k) is satisfied, that is, it is determined that the transient target value EXVTref (k) has not yet reached the final target value. In this case, the exhaust VVT transient target value EXVTref (k) is obtained by subtracting the current value INVT (k) of the intake VVT advance amount from the latest target overlap period OV (k) acquired in step 200. Calculated (step 204).

  Since the case where the routine shown in FIG. 8 is started is a case where the valve overlap period existing in the exhaust stroke is weighted, as described above, in the initial stage after the start of the control of this routine, the intake air The exhaust VVT retard amount is adjusted without changing the VVT advance amount. For this reason, according to the processing of this step 204, for example, referring to the example shown in FIG. 3, the transient target value EXVTref (k) of the exhaust VVT retardation amount is the value at the time of deceleration request (about 28 ° CA). Is gradually changed with the change of the target overlap period OV (k) toward 10 ° CA which is the final target value of the exhaust VVT retardation amount.

  On the other hand, if it is determined in step 202 that exhaust VVT final target value <exhaust VVT transient target value EXVTref (k) is not established, that is, transient target value EXVTref (k) has reached the final target value. Is determined, the intake VVT transient target value INVTref (k) is a value obtained by subtracting the final target value of the exhaust VVT advance amount from the latest target overlap period OV (k) acquired in step 200. (Step 206).

  That is, according to the processing of step 206, when the exhaust VVT retardation amount reaches its final target value, the intake valve for setting the valve overlap period as the target overlap period in the operating state after deceleration, and The remaining control of the exhaust valve control, that is, the retard control of the intake VVT is executed. For this purpose, the transient target value INVTref (k) of the intake VVT advance amount referred to in this step 206 is gradually increased every predetermined control period in accordance with the decrease in the target overlap period OV (k) in step 200. It will be changed to. For example, in the example shown in FIG. 3, the target overlap period OV (k) from the intake VVT advance amount of about 22 ° CA toward the final target value of the intake VVT advance amount of 0 ° CA. It will be changed gradually with changes.

  In the routine shown in FIG. 8, after step 204 or 206 is executed, the transient target value INVTref (k) of the intake VVT advance amount and the transient target value EXVTref (k) of the exhaust VVT retard amount are respectively set. It is determined whether or not the final target value matches (step 208). As a result, while this determination is not established, the processing of steps 200 to 204 or the processing of steps 200, 202, and 206 is repeatedly executed. On the other hand, when this determination is established, A series of processing is completed.

  In the routine shown in FIG. 7, when it is determined in step 102 that the current signal from the oxygen sensor 64 indicates a rich output, the valve overlap period existing in the intake stroke is weighted. However, the valve overlap period is reduced so that the target value after deceleration (after the low load transition) is reached (step 106).

FIG. 9 is a flowchart of a subroutine showing specific processing of step 106 in FIG. In FIG. 9, the same steps as those shown in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
Since the case where the routine shown in FIG. 9 is started is a case where the valve overlap period existing during the intake stroke is weighted, as described above, in the initial stage after the start of the control of this routine, the exhaust VVT is started. The intake VVT advance amount is adjusted without changing the retard amount. That is, the processing of this routine basically corresponds to the processing of the routine shown in FIG. 8 in which the control of the intake valve 66 and the control of the exhaust valve 68 are replaced. For this reason, descriptions similar to those described in the routine shown in FIG. 8 are omitted or simplified as appropriate.

  That is, in this routine, after the target overlap period OV (k) is calculated (step 200), the final target value of the intake VVT advance amount is greater than the transient target value INVTref (k) of the intake VVT advance amount. It is determined whether or not it is small, that is, whether or not the transient target value INVTref (k) has reached the final target value (step 300).

  As a result, when it is determined that the intake VVT final target value <the intake VVT transient target value INVTref (k) is satisfied, that is, when it is determined that the transient target value INVTref (k) has not yet reached the final target value. The intake VVT transient target value INVTref (k) is calculated as a value obtained by subtracting the current value EXVT (k) of the exhaust VVT retardation amount from the latest target overlap period OV (k) acquired in step 200. (Step 302).

  On the other hand, when it is determined in step 300 that the intake VVT final target value <the intake VVT transient target value INVTref (k) is not established, that is, the transient target value INVTref (k) has reached the final target value. Is determined, the exhaust VVT transient target value EXVTref (k) is a value obtained by subtracting the final target value of the intake VVT retardation amount from the latest target overlap period OV (k) acquired in step 200. (Step 304).

  Further, in the routine shown in FIG. 9, the processing of step 302 or 304 described above is performed with the transient target value INVTref (k) of the intake VVT advance amount and the transient target value EXVTref (k) of the exhaust VVT retard amount as the final target. The process continues until the value matches (step 208).

  Incidentally, in the first embodiment described above, depending on whether the signal of the oxygen sensor 64 disposed downstream of the upstream catalyst 58 indicates a rich output or a lean output, that is, inside the catalyst. The operation order of the retard angle control of the intake valve 66 and the advance angle control of the exhaust valve 68 is changed in accordance with the oxygen concentration of the exhaust gas. However, in the present invention, the method of changing the operation sequence of the intake valve opening timing control and the exhaust valve closing timing control according to the internal state of the catalyst is not limited to this. That is, the internal state of the catalyst referred to in the present invention is not limited to the state of the oxygen concentration inside the catalyst in Embodiment 1 described above, and may be, for example, the catalyst temperature.

  In the state where the temperature of the upstream catalyst 58 and the like is high, if a large amount of oxygen is supplied by the blow-in of intake air, the upstream catalyst 58 and the like may be deteriorated. Therefore, when the temperature of the upstream catalyst 58 or the like (the estimated value calculated by the ECU 80 or the measured value by the sensor) reaches a predetermined value or more during deceleration from the supercharging state, the valve over existing in the exhaust stroke is exceeded. In order to weight the lap period, the advance control of the closing timing of the exhaust valve 68 may be performed and then the retard control of the opening timing of the intake valve 66 may be performed. According to such control, it is possible to create a situation in which intake air blow-off is difficult to occur during deceleration when the upstream catalyst 58 is in a high temperature state, and the high temperature catalyst 58 is exposed to a large amount of oxygen. Can be suppressed satisfactorily. Thus, it is possible to satisfactorily prevent the upstream catalyst 58 and the like from deteriorating during deceleration from the supercharged state.

  Further, the internal state of the catalyst referred to in the present invention is not limited to the above-described oxygen concentration state inside the catalyst and the temperature state of the catalyst, and may be, for example, the oxygen storage amount OSC of the catalyst. More specifically, when the oxygen storage amount OSC of the upstream catalyst 58 is equal to or greater than a predetermined value during deceleration from the supercharging state, the valve overlap period existing in the exhaust stroke is weighted. After the advance timing control of the closing timing of the exhaust valve 68, the retard timing control of the opening timing of the intake valve 66 may be performed. According to such control, it is possible to create a situation in which intake air is less likely to blow through when the oxygen storage amount OSC of the upstream catalyst 58 has reached an allowable amount. It is possible to satisfactorily prevent the supply of oxygen. As a result, the oxygen storage amount OSC of the upstream catalyst 58 can be reduced to an appropriate amount.

  Further, when the oxygen storage amount OSC of the upstream catalyst 58 is less than a predetermined value at the time of deceleration from the supercharging state, the intake valve 66 is weighted so that the valve overlap period existing during the intake stroke is weighted. The advance timing control for the closing timing of the exhaust valve 68 may be performed after the opening timing retard control. According to such control, it is possible to create a situation in which intake air blow-through easily occurs during deceleration in a situation where the oxygen storage amount OSC of the upstream catalyst 58 is insufficient, and sufficient oxygen is supplied to the upstream catalyst 58. Can be supplied. As a result, the oxygen storage amount OSC of the upstream catalyst 58 can be increased to an appropriate amount. The oxygen storage amount OSC of the upstream catalyst 58 is from the time when the control target air-fuel ratio upstream of the upstream catalyst 58 is switched from rich to lean until the output of the oxygen sensor 64 downstream of the upstream catalyst 58 reverses from rich to lean. And the capacity of the upstream catalyst 58 can be calculated.

  In the first embodiment described above, taking the case where the signal of the oxygen sensor 64 indicates a rich output as an example, as shown in the time chart of FIG. 5, first, the intake VVT advance amount is determined. After retarding to the target value, the exhaust VVT retard amount is advanced to the target value. However, the present invention is not limited to such an example as long as the operation sequence of the intake valve opening timing control and the exhaust valve closing timing control is changed according to the internal state of the catalyst. Absent. That is, for example, taking the time chart of FIG. 5 as an example, if the control of the intake VVT advance amount is started first, the exhaust VVT advance amount is exhausted before the intake VVT advance amount is retarded to its target value. The advance control of the VVT retardation amount may be started.

  Furthermore, according to the present invention, the control speed of the intake valve opening timing control and the exhaust valve closing timing control may be made different according to the internal state of the catalyst. That is, for example, similarly to the example of the time chart of FIG. 5 described above, the case where the signal of the oxygen sensor 64 shows a rich output will be described as an example. When the valve overlap period is reduced during deceleration from the supercharging state, The control speed of the retard control of the intake VVT advance amount at the initial stage after the start of the decrease of the valve overlap period while simultaneously starting the execution of the retard control of the VVT advance amount and the advance control of the exhaust VVT retard amount. May be made higher than the control speed of the advance control of the exhaust VVT retard amount. Also by such control, it is possible to weight the valve overlap period existing during the exhaust stroke.

  In the first embodiment described above, the ECU 80 executes the processing of step 104 or 106 according to the determination result of step 102, whereby the “overlap period control means” in the first invention is By executing the processing of step 102, the “catalyst information acquisition means” in the first invention is realized. The upstream catalyst 58 corresponds to the “catalyst” in the first invention.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure for demonstrating the relationship between the motion of a piston and the blow-in amount of intake air. It is a figure showing the amount of retardation of an exhaust valve, and the amount of advance of an intake valve by the relation with the shaft torque of an internal-combustion engine. It is a figure for demonstrating how to adjust the valve timing of an intake / exhaust valve when the deceleration request | requirement is issued from the supercharging state, when the signal of an oxygen sensor shows a rich output. It is a time chart showing the operation | movement in the case shown in the said FIG. It is a figure for demonstrating how to adjust the valve timing of the intake / exhaust valve when the deceleration request | requirement is issued from the supercharging state, when the signal of an oxygen sensor shows a lean output. It is a flowchart of the main routine performed in Embodiment 1 of the present invention. It is a flowchart of the subroutine which shows the specific process of step 104 in FIG. It is a flowchart of the subroutine which shows the specific process of step 106 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 14 Combustion chamber 20 Turbo supercharger 32 Upstream pressure sensor 36 Downstream pressure sensor 52 Exhaust passage 58 Upstream catalyst 60 Downstream catalyst 62 Air-fuel ratio sensor 64 Oxygen sensor 66 Intake valve 68 Exhaust valve 70 Intake variable movement Valve mechanism 72 Exhaust variable valve mechanism 80 ECU (Electronic Control Unit)
82 Crank angle sensor 84 Piston

Claims (7)

A supercharger for supercharging the intake air;
An intake variable valve mechanism that makes at least the opening timing of the intake valve variable;
An exhaust variable valve mechanism for varying at least the closing timing of the exhaust valve;
An overlap period control means for adjusting a valve overlap period in which the intake valve opening period and the exhaust valve opening period overlap by controlling the opening timing of the intake valve and the closing timing of the exhaust valve;
A catalyst disposed in the exhaust passage;
Catalyst information acquisition means for acquiring information relating to the internal state of the catalyst,
When changing the valve overlap period when decelerating from a state in which the valve overlap period exists, the overlap period control means controls the opening timing of the intake valve and the exhaust gas according to the internal state of the catalyst. Changing the control sequence of the valve closing timing control or changing the control speed of the intake valve opening timing and the exhaust valve closing timing control ;
The overlap period control means changes the operation sequence or reduces the control speed when decelerating from the state where the supercharging pressure is equal to or greater than a predetermined value of positive pressure and the valve overlap period exists. control device for an internal combustion engine with a supercharger, characterized in that varying the. The catalyst information acquisition means is means for acquiring oxygen concentration information inside the catalyst,
When the oxygen concentration inside the catalyst is equal to or greater than a predetermined value, the overlap period control means first advances the closing timing of the exhaust valve to the target value after deceleration, and then opens the intake valve. control device for an internal combustion engine with a supercharger according to claim 1, wherein the retarding the timing to the target value after deceleration. The catalyst information acquisition means is means for acquiring oxygen concentration information inside the catalyst,
When the oxygen concentration inside the catalyst is less than a predetermined value, the overlap period control means delays the opening timing of the intake valve to the target value after deceleration before closing the exhaust valve. control device for an internal combustion engine with a supercharger according to claim 1, wherein the to advance to the target value after deceleration the time. The control device for an internal combustion engine with a supercharger according to any one of claims 1 to 3 , wherein the oxygen concentration acquisition means is an oxygen concentration sensor disposed in an exhaust passage downstream of the catalyst. . The catalyst information acquisition means is means for acquiring temperature information of the catalyst,
When the temperature of the catalyst is equal to or higher than a predetermined value, the overlap period control means decelerates the opening timing of the intake valve after advancing the closing timing of the exhaust valve to the target value after deceleration first. 2. The control apparatus for an internal combustion engine with a supercharger according to claim 1 , wherein the control is delayed to a later target value. The catalyst information acquisition means is means for acquiring oxygen storage amount information of the catalyst,
When the oxygen storage amount of the catalyst is equal to or greater than a predetermined value, the overlap period control means advances the closing timing of the exhaust valve to the target value after deceleration first, and then opens the intake valve. 2. The control device for an internal combustion engine with a supercharger according to claim 1 , wherein the control is delayed to a target value after deceleration. The catalyst information acquisition means is means for acquiring oxygen storage amount information of the catalyst,
When the oxygen storage amount of the catalyst is less than a predetermined value, the overlap period control means delays the opening timing of the intake valve to the target value after deceleration before closing the exhaust valve. control device for an internal combustion engine with a supercharger according to claim 1, wherein the to advance to the target value after deceleration to.

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