JP5338709B2 - Control device for internal combustion engine - Google Patents

Description

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

  An internal combustion engine including a variable valve timing mechanism capable of changing a valve overlap amount (hereinafter referred to as a valve overlap amount) in which both an intake valve and an exhaust valve are opened, and a supercharger for supercharging an intake system As a control device, there is known a control device that lowers the exhaust pressure by opening a waste gate valve when a response delay occurs when reducing the valve overlap amount during deceleration (for example, Patent Document 1). reference).

  According to the control device, it is possible to suppress the blow-back phenomenon that occurs when the exhaust pressure becomes higher than the intake pressure during the valve overlap period during deceleration.

JP 2007-239604 A

  By the way, a blow-through phenomenon occurs when the intake pressure becomes higher than the exhaust pressure during the valve overlap period during acceleration. This blow-through phenomenon can be suppressed by reducing the valve overlap amount during acceleration. However, if a response delay occurs when the valve overlap amount is reduced during acceleration, the effect of suppressing the blow-through phenomenon is reduced. Furthermore, in an internal combustion engine provided with a supercharger, the effect of suppressing the blow-through phenomenon is further reduced.

  In view of the above circumstances, an object of the present invention is to provide a control device for an internal combustion engine that can effectively suppress a blow-through phenomenon that occurs during acceleration in an internal combustion engine that includes a supercharger and that can adjust a valve overlap amount. And

In order to achieve the above object, a control device for an internal combustion engine includes a supercharger that supercharges an intake system of the internal combustion engine, an operating state detection means that detects an operating state of the internal combustion engine, an intake valve of the internal combustion engine, A variable valve timing mechanism capable of adjusting a valve overlap amount with the exhaust valve, a valve overlap amount detection means for detecting the valve overlap amount based on an operation state detected by the operation state detection means, A supercharging pressure detecting means for detecting a supercharging pressure by a charger; and a valve overlap detected by the valve overlap amount detecting means when the operating state detecting means detects that the internal combustion engine is in an acceleration state. the amount is a value response delay occurs in reduction of the valve overlap amount, and the supercharging pressure detected by the supercharging pressure detection means at a predetermined pressure If it is above, and a supercharging pressure lowering means for decreasing the supercharging pressure.

In the control apparatus for an internal combustion engine, the operating state detection means may be a rotation speed detection means for detecting the rotation speed of the internal combustion engine, and the supercharging pressure reduction means is detected by the rotation speed detection means. The supercharging pressure may be decreased when the rotational speed is equal to or greater than a predetermined value.
In the control apparatus for an internal combustion engine, the internal combustion engine may include a waste gate valve provided in a bypass flow path that bypasses the supercharger, and the supercharging pressure lowering means opens the waste gate valve, The supercharging pressure may be reduced.

  According to the control apparatus for an internal combustion engine, a blow-through phenomenon that occurs during acceleration can be effectively suppressed in an internal combustion engine that includes a supercharger and that can adjust the valve overlap amount.

1 is a schematic configuration diagram of a supercharged internal combustion engine to which a control device according to an embodiment is applied. It is a block diagram which shows the structure of engine ECU. It is a flowchart for demonstrating the supercharging pressure control at the time of acceleration by engine ECU. It is a figure which shows the engine operating state in which a blow-through phenomenon may generate | occur | produce.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic configuration diagram of an internal combustion engine with a supercharger to which a control device according to an embodiment of the present invention is applied. As shown in this figure, an engine 1 as an internal combustion engine with a supercharger includes a supercharger 10 and a variable valve timing mechanism 100. The supercharger 10 is an exhaust turbocharger that includes a turbine 12 disposed in an exhaust system 50 and a compressor 14 disposed in an intake system 40 and is driven by exhaust energy. The variable valve timing mechanism (VVT) 100 includes an intake side variable valve timing mechanism (intake side VVT) 101 disposed on the intake side and an exhaust side variable valve timing mechanism (exhaust side VVT) 102 disposed on the exhaust side. The opening and closing timing of the intake valve and the exhaust valve is variable. The intake side VVT 101 and the exhaust side VVT 102 are driven by a mechanical, electric, or hydraulic actuator.

The engine 1 includes a cylinder block 20, a cylinder head 30 fixed on the cylinder block 20, an intake system 40 for supplying a mixture of fuel and air to the cylinder block 20, a cylinder And an exhaust system 50 for releasing the exhaust gas from the block unit 20 to the outside.
The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. The cylinder 21, the head of the piston 22, and the cylinder head portion 30 form a combustion chamber (cylinder) 25.

  The cylinder head portion 30 opens and closes a pair of intake ports 31 that communicate with the combustion chamber 25, a pair of intake valves 32 that open and close each intake port 31, a pair of exhaust ports 33 that communicate with the combustion chamber 25, and each exhaust port 33. A pair of exhaust valves 34, an ignition plug 37, an igniter 38 having an ignition coil for generating a high voltage to be applied to the ignition plug 37, and an injector 39 for injecting fuel into the intake port 31 are provided.

  The intake system 40 includes an intake manifold 41 that communicates with the intake port 31, a surge tank 42 that forms part of the intake manifold 41, an intake duct 43 that forms an intake passage with the intake port 31, the intake manifold 41, and the surge tank 42, The compressor 14 of the supercharger 10 communicated with the duct 43 and the intake manifold 41, and the throttle valve 46 disposed in the intake manifold 41 are provided.

  The exhaust system 50 includes an exhaust pipe 51 having an exhaust manifold that communicates with the exhaust port 33 and forms an exhaust passage together with the exhaust port 33, a turbocharger turbine 12 disposed in the exhaust pipe 51, a catalyst 52, A waste gate 53 that is a flow path that bypasses the turbine 12 and a waste gate valve 54 that adjusts the opening area of the waste gate 53 are provided.

  The supercharger 10 includes a turbine 12 disposed in the exhaust system 50 and a compressor 14 disposed in the intake system 40 and rotated by the output of the turbine 12. The waste gate valve 54 reduces the opening area of the waste gate 53 and increases the exhaust pressure, thereby increasing the output of the turbine 12 and increasing the supercharging pressure by the supercharger 10. On the other hand, the waste gate valve 54 increases the opening area of the waste gate 53 to lower the exhaust pressure, whereby the output of the turbine 12 is reduced and the supercharging pressure by the supercharger 10 is reduced.

The throttle valve 46 is rotatably supported by the intake manifold 41, and its opening degree is adjusted in conjunction with an accelerator operation or by being driven from a throttle valve actuator. As a result, the throttle valve 46 can change the opening area of the intake manifold 41.
On the other hand, this system includes an intake pressure sensor 61, a crank angle sensor 62, a cam angle sensor 63, an accelerator opening sensor 64, and an engine ECU 70.

The intake pressure sensor 61 detects the pressure of intake air downstream of the throttle valve 46, that is, the pressure in the surge tank 42 (hereinafter referred to as intake manifold pressure) Pim, and outputs a detection signal to the engine ECU 70.
The crank angle sensor 62 detects a phase angle (hereinafter referred to as crank angle) Cra of the crankshaft 24 and outputs a detection signal to the engine ECU 70. Cam angle sensor 63 detects a cam phase angle (hereinafter referred to as cam angle) Cma and outputs a detection signal to engine ECU 70. The accelerator opening sensor 64 detects an operation amount (hereinafter referred to as accelerator opening) Acc of the accelerator pedal 65 operated by the driver, and outputs a detection signal to the engine ECU 70.

The engine ECU 70 performs predetermined arithmetic processing by a built-in microcomputer while inputting signals from the various sensors described above, and performs a fuel injection system such as an injector 39, a spark plug 37 (ignition system), and an overload. A drive signal is output to the intake system such as the feeder 10 and the variable valve timing mechanism 100.
FIG. 2 is a functional block diagram showing a configuration of engine ECU 70. As shown in this figure, the engine ECU 70 includes a CPU 71, a memory 72, an input / output port (IO) 73, and the like. The input / output port 73 converts electrical signals from various sensors into signals for digital arithmetic processing.

The input / output port 73 receives as input signals a signal corresponding to the intake manifold pressure Pim detected by the intake pressure sensor 61, a signal corresponding to the crank angle Cra detected by the crank angle sensor 62, and a cam angle sensor 63. A signal corresponding to the detected cam angle Cma and a signal corresponding to the accelerator opening Acc detected by the accelerator opening sensor 64 are supplied.
The memory 72 stores a control program for executing supercharging pressure control during acceleration, which will be described later. The control program includes a map showing the relationship between the phase of the intake valve 32 and the exhaust valve 34 and the rotational speed Ne, and the relationship between the valve overlap amount Vor and the rotational speed Ne. Further, the memory 72 temporarily stores various data acquired when executing the boost pressure control during acceleration.

The CPU 71 calculates the rotational speed Ne of the engine 1 based on the crank angle Cra detected by the crank angle sensor 62. Further, the CPU 71 calculates a valve overlap amount Vor at which both the intake valve 32 and the exhaust valve 34 are opened based on the cam angle Cma detected by the cam angle sensor 63.
Then, the CPU 71 determines the target valve overlap amount corresponding to the engine operating state based on a map indicating the relationship between the rotational speed Ne, the volumetric efficiency Ve (engine load), and the phases of the cams of the intake valve 32 and the exhaust valve 34. A drive signal is output to the actuators of the intake side variable valve timing mechanism 101 and the exhaust side variable valve timing mechanism 102 so that the calculated target valve overlap amount is obtained. Further, the CPU 71 executes supercharging pressure control during acceleration based on a control program stored in the memory 72.

  Here, at the time of acceleration, since the supercharger 10 is operated and the intake manifold pressure Pim increases, the larger the valve overlap amount Vor, the more the unburned gas blows through. Therefore, the CPU 71 uses the intake side variable valve timing mechanism based on a map showing the relationship between the cam phase of the intake valve 32 and the exhaust valve 34 and the rotational speed Ne so that the valve overlap amount Vor is reduced during acceleration. A drive signal is output to 101 and the exhaust side variable valve timing mechanism 102.

Further, the CPU 71 outputs a drive signal to the actuator of the waste gate valve 54 based on the control program stored in the memory 72. Here, the waste gate valve 54 is closed in principle during acceleration, but is opened as necessary as will be described later.
FIG. 3 is a flowchart for explaining the supercharging pressure control during acceleration of the vehicle. As shown in this flowchart, first, in step 100, the CPU 71 calculates the rotational speed Ne of the engine 1 based on the crank angle Cra detected by the crank angle sensor 62. Next, in step 101, the CPU 71 determines whether or not the rotational speed Ne has increased, that is, whether or not the engine 1 is in an acceleration state. If the determination is affirmative, the process proceeds to step 102, whereas if the determination is negative, the processing routine is terminated.

Next, in step 102, the CPU 71 determines whether or not the calculated rotation speed Ne is equal to or greater than a threshold value (for example, 2000 rpm). If the determination is affirmative, the process proceeds to step 103. If the determination is negative, the processing routine is terminated.
In step 103, the CPU 71 calculates a valve overlap amount Vor based on the cam angle Cma detected by the cam angle sensor 63. Next, in step 104, the CPU 71 determines whether or not the calculated valve overlap amount Vor is greater than or equal to a value corresponding to the calculated rotation speed Ne with reference to a map stored in the memory 72. To do. Here, when the engine 1 is accelerated, the valve overlap amount Vor is decreased. In this step, it is determined whether or not a response delay of the decrease in the valve overlap amount Vor has occurred. If the determination is affirmative, the process proceeds to step 105, whereas if the determination is negative, the processing routine is terminated.

  In step 105, the CPU 71 calculates the supercharging pressure Psc based on a signal corresponding to the intake manifold pressure Pim detected by the intake pressure sensor 61. Next, in step 106, the CPU 71 determines whether or not the calculated boost pressure Psc is greater than or equal to a threshold value stored in the memory 72. If the determination is affirmative, the routine proceeds to step 107, whereas if the determination is negative, the processing routine is terminated.

  Here, the lower the rotation speed Ne, the lower the supercharging pressure Psc, and the lower the supercharging pressure Psc, the smaller the blow-through. That is, if the rotational speed and the supercharging pressure are low, the occurrence of blow-through can be suppressed within an allowable range regardless of the valve overlap amount Vor. Therefore, a predetermined supercharging pressure obtained in advance that can suppress the occurrence of blow-through within an allowable range is set as a threshold value of the supercharging pressure Psc.

In step 107, the CPU 71 outputs a drive signal to the actuator of the waste gate valve 54, and changes the waste gate valve 54 from the closed state to the open state. Thereby, when the exhaust pressure is reduced in the exhaust system 50, the output of the turbine 12 is reduced, and the supercharging pressure by the supercharger 10 is reduced. Thus, the processing routine is finished.
FIG. 4 is a diagram showing an engine operating state in which a blow-through phenomenon may occur. As shown in this figure, the high-speed and high-load region is a blow-by region.

  Here, since the valve overlap amount Vor decreases as the speed increases, if the high-speed and high-load region C is accelerated to the high-speed and low-load region A, the blow-through decreases. Further, at the acceleration start stage, although the valve overlap amount Vor is large, the supercharging pressure Psc does not increase, so that the blow-through is reduced in the low speed high load area B before reaching the high speed high load area C. Then, after accelerating to the high speed and high load area C after passing through the low speed and high load area B, the boost pressure Psc increases, so if there is a response delay in reducing the valve overlap amount Vor, Will increase.

  Therefore, in the supercharging pressure control according to the present embodiment, the supercharging pressure Psc is less than the predetermined value, and the low speed high load region B where the valve overlap amount Vor is less than the predetermined value is excessive. While the supply pressure Psc is increased, in the high speed and high load region C where the boost pressure Psc is greater than or equal to a predetermined value, the valve overlap amount Vor is greater than the predetermined value, that is, there is a response delay in reducing the valve overlap amount Vor. In addition, the supercharging pressure Psc is decreased. As a result, blowout of unburned gas at the time of acceleration can be suppressed. Therefore, various problems such as deterioration in catalyst performance due to overheating of the catalyst due to blowthrough and increase in exhaust smoke due to discharge of unburned gas. Can be suppressed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the present embodiment, the supercharging pressure of the supercharger 10 is obtained based on the intake manifold pressure Pim detected by the intake pressure sensor 61, but is estimated based on parameters such as the rotational speed Ne and the accelerator opening. Also good. The supercharger 10 may be an electric supercharger. In this case, the supercharging pressure may be adjusted by adjusting the rotation speed of the motor of the electric supercharger.

1 Engine 10 Supercharger 12 Turbine 14 Compressor 20 Cylinder block portion 21 Cylinder 22 Piston 23 Connecting rod 24 Crankshaft 25 Combustion chamber 30 Cylinder head portion 31 Intake port 32 Intake valve 33 Exhaust port 34 Exhaust valve 37 Spark plug 38 Igniter 39 Injector 40 Intake system 41 Intake manifold 42 Surge tank 43 Intake duct 46 Throttle valve 50 Exhaust system 51 Exhaust pipe 52 Catalyst 53 Waste gate (bypass passage)
54 Wastegate valve 61 Intake pressure sensor (supercharging pressure detection means)
62 Crank angle sensor (operating state detection means, rotation speed detection means)
63 Cam angle sensor 64 Accelerator opening sensor 65 Accelerator pedal 70 Engine ECU (Operating state detection means, valve overlap amount detection means, boost pressure detection means, boost pressure reduction means, rotation speed detection means)
71 CPU (operating state detection means, valve overlap amount detection means, supercharging pressure detection means, supercharging pressure reduction means, rotation speed detection means)
72 Memory 73 Input / output port 100 Variable valve timing mechanism 101 Intake side variable valve timing mechanism 102 Exhaust side variable valve timing mechanism

Claims (3)

A supercharger for supercharging the intake system of the internal combustion engine;
An operating state detecting means for detecting an operating state of the internal combustion engine;
A variable valve timing mechanism capable of adjusting a valve overlap amount between an intake valve and an exhaust valve of the internal combustion engine;
Valve overlap amount detection means for detecting the valve overlap amount based on the operation state detected by the operation state detection means;
A supercharging pressure detecting means for detecting a supercharging pressure by the supercharger;
When the operating state detection means detects that the internal combustion engine is in an acceleration state, the valve overlap amount detected by the valve overlap amount detection means is a value that causes a response delay in reducing the valve overlap amount . And, when the supercharging pressure detected by the supercharging pressure detecting means is equal to or higher than a predetermined pressure, a supercharging pressure reducing means for reducing the supercharging pressure;
A control device for an internal combustion engine. The operating state detecting means is a rotational speed detecting means for detecting the rotational speed of the internal combustion engine,
The control device for an internal combustion engine according to claim 1, wherein the supercharging pressure reduction means reduces the supercharging pressure when the rotational speed detected by the rotational speed detection means is a predetermined value or more. A waste gate valve provided in a bypass passage for bypassing the supercharger,
The control device for an internal combustion engine according to claim 1 or 2, wherein the supercharging pressure lowering means lowers the supercharging pressure by opening the waste gate valve.

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