Control device for an internal combustion engine

Abstract

Internal combustion engine control device for an internal combustion engine (2) comprising: a turbocharger (60) which pressurizes intake air using exhaust gases from an internal combustion engine (2), a bypass channel (46) which is configured to bypass a turbine (60A) of the turbocharger (60) so that exhaust gases flow through this channel, and a wastegate valve (65) which regulates the amount of exhaust gases flowing through the bypass channel (46), wherein the internal combustion engine control device comprises: a control unit (3) that performs normal opening control to close the wastegate valve (65) according to an increase in the opening degree of an accelerator pedal (22A), wherein the control unit (3) in a non-charging range, within which the accelerator pedal opening degree is equal to or less than a first accelerator pedal opening degree, controls the wastegate valve (65) to an opening degree which is close to a closed state with respect to a fully open state, and wherein in the non-charging range, the control unit (3): the wastegate valve (65) controls to a first opening degree corresponding to the first accelerator pedal opening degree, if the accelerator pedal opening amount corresponds to a first accelerator pedal opening amount as a predetermined accelerator pedal opening degree; the wastegate valve (65) is controlled to a fully closed state when the accelerator pedal opening degree is less than a second accelerator pedal opening degree, which in turn is less than the first accelerator pedal opening degree, and controls the opening degree of the wastegate valve (65) to a second opening degree which is smaller than the first opening degree and corresponds to the accelerator pedal opening degree when the accelerator pedal opening degree is equal to or greater than the second accelerator pedal opening degree and smaller than the first accelerator pedal opening degree.

Description

BACKGROUND OF THE TECHNOLOGY 1. Technical Field

[0001] The present invention relates to a control device for an internal combustion engine. 2. State of the art

[0002] An internal combustion engine mounted in a vehicle, e.g. a motor vehicle, is known in which exhaust gases are used to charge intake air by means of a turbocharger, wherein the turbocharger comprises a turbine set in rotation by exhaust gases and a compressor set in rotation together with the turbine to charge the intake air.

[0003] In the internal combustion engine, which includes the turbocharger, there is a delay in the turbocharging process, also known as turbo lag. This delay is a phenomenon where the turbocharging effect only kicks in when the engine speed increases and the amount of exhaust gases increases with further acceleration of the accelerator pedal.

[0004] JP 2015-214920 A discloses a method in a conventional control device for an internal combustion engine for overcoming a turbo lag. In the method disclosed in JP 2015-214920 A, a first valve and a second valve in an intake manifold are controlled such that they are closed at the start of acceleration if subsequent acceleration of the vehicle in a turbocharging range is expected.

[0005] German patent application DE 10 2013 214 658 A1 discloses a control device for an internal combustion engine that improves acceleration performance while maintaining fuel efficiency in a non-supercharged operating range. This is achieved by providing a bypass line that bypasses a supercharger turbine. A wastegate valve is provided in the bypass line for adjusting the flow path area of ​​the bypass line via a wastegate actuator. For operation in the non-supercharged operating range, the opening degree of the wastegate valve is set to fully close when the ratio of the intake manifold pressure to atmospheric pressure is less than a threshold value.

[0006] German patent application DE 10 2006 000 136 A1 discloses an internal combustion engine comprising a throttle valve for an intake port and a turbocharger with an exhaust turbine and an intake compressor. The intake compressor is located in the intake port. A wastegate valve, operated by an electrical actuator, is provided for a bypass port that bypasses the exhaust turbine. A control unit for the internal combustion engine includes an adjustment unit and a control unit. The adjustment unit sets the position of the wastegate valve to a target position under normal operating conditions. This target position is outside a range in which the wastegate valve is in a substantially fully closed position.The control unit controls the position of the wastegate valve so that the position of the wastegate valve corresponds to the target position.

[0007] German patent application DE 10 2016 214 486 A1 relates to a method for regenerating a particulate filter and / or heating a catalyst in the exhaust manifold of an internal combustion engine. For this purpose, the intake manifold of the internal combustion engine is connected to the exhaust manifold of the internal combustion engine downstream of a compressor via a secondary air line, with the secondary air line opening into the exhaust manifold upstream of the particulate filter or the catalyst. A pressure accumulator is arranged on the secondary air line, which is designed to be filled with fresh air from the intake manifold and to release the compressed air into the exhaust manifold for the regeneration of the particulate filter or the heating of the catalyst. The energy of a turbocharger is also used to fill the pressure accumulator during the overrun phase of the internal combustion engine.

[0008] German patent application DE 10 2014 216 705 A1 concerns a method for determining the fully closed position of a wastegate valve. In one method, a control signal for an open position is received for a wastegate valve in a low-stroke range with respect to a valve seat. Before the position control signal is executed, the wastegate valve is only temporarily closed in order to determine a fully closed position. SUMMARY OF THE INVENTION

[0009] The problem with the method disclosed in JP 2015 - 214 920 A is that, because the first valve and the second valve are closed after acceleration of the vehicle is expected, a desired state of charging cannot be achieved in an initial phase.

[0010] The object of the present invention is to provide a control device for an internal combustion engine that is capable, in an initial phase at the time of switching from a non-charging range to a charging range, of achieving a desired boost pressure and improving acceleration response in accordance with an increase in the amount of throttle input. This object is achieved by the features of the main claim. Advantageous embodiments of the invention are the subject of the dependent claims.

[0011] According to aspects of the present invention, an internal combustion engine control device is provided for an internal combustion engine, comprising: a turbocharger that pressurizes intake air using exhaust gases from an internal combustion engine, a bypass channel configured to bypass a turbine of the turbocharger so that exhaust gases flow through this channel, and a wastegate valve that regulates the amount of exhaust gas flowing through the bypass channel, wherein the internal combustion engine control device comprises: a control unit that performs normal opening control to close the wastegate valve in accordance with an increase in the degree of opening of an accelerator pedal, wherein the control unit, in a non-charged range within which the degree of opening of the accelerator pedal is equal to or less than a first degree of opening of the accelerator pedal, controls the wastegate valve to an opening degree,which is close to a fully open state with respect to a fully open state, and wherein in the non-charging range, the control unit: controls the wastegate valve to a first degree of opening corresponding to a first accelerator pedal opening degree when the accelerator pedal opening amount, as a predetermined accelerator pedal opening degree, corresponds to a first accelerator pedal opening amount, and controls the wastegate valve to a fully closed state when the accelerator pedal opening degree is less than a second accelerator pedal opening degree, which in turn is less than the first accelerator pedal opening degree, and controls the degree of opening of the wastegate valve to a second degree of opening that is less than the first degree of opening and corresponds to the accelerator pedal opening degree when the accelerator pedal opening degree is equal to or greater than the second accelerator pedal opening degree and less than the first accelerator pedal opening degree.

[0012] In this way, according to the invention, it is possible in an initial phase, at the time of switching from the non-charging range to the charging range, in accordance with an increase in the actuation amount of an accelerator pedal, to achieve a desired boost pressure and to improve response behavior during acceleration. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a circuit diagram of a vehicle equipped with an internal combustion engine control device according to an embodiment of the present invention; Fig. Figure 2 is a flowchart illustrating the operation of an internal combustion engine control device according to an embodiment of the present invention; Fig. Figure 3 is a time sequence diagram representing a transition of a vehicle state at the time of acceleration of a vehicle equipped with the internal combustion engine control device according to an embodiment of the present invention; and Fig. Figure 4 is a timing diagram illustrating a control for opening and closing a wastegate valve by the internal combustion engine control device according to an embodiment of the present invention. DESCRIPTION OF EXECUTION FORMS

[0013] An internal combustion engine control device according to embodiments of the present invention is an internal combustion engine control device for an internal combustion engine, comprising: a turbocharger that pressurizes intake air using exhaust gases from an internal combustion engine, a bypass channel configured to bypass a turbine of the turbocharger so that exhaust gases flow through this channel, and a wastegate valve that regulates the amount of exhaust gas flowing through the bypass channel, wherein the internal combustion engine control device comprises: a control unit that performs normal opening control to close the wastegate valve when the accelerator pedal opening degree is greater than a predetermined accelerator pedal opening degree, wherein the control unit, in a non-charged range in which the accelerator pedal opening degree is equal to or less than the predetermined accelerator pedal opening degree,The wastegate valve is controlled to an opening degree that is close to a fully open state. Accordingly, with the combustion engine control device according to the embodiments of the present invention, a desired boost pressure can be achieved and acceleration response improved in an initial phase, at the time of switching from a non-charging to a charging state, in accordance with an increase in the amount of throttle input. EXECUTION FORMS

[0014] In the following, with reference to the drawings, an internal combustion engine control device according to the embodiments of the present invention will be described in more detail.

[0015] In Fig. 1 comprises a vehicle 1 equipped with an internal combustion engine control device according to embodiments of the present invention, an internal combustion engine 2 and an electronic control unit (ECU) 3 corresponding to a control unit.

[0016] The internal combustion engine 2 is designed as a four-stroke engine, which, in the course of two back-and-forth movements of a piston within a cylinder, performs a series of four strokes, comprising an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke.

[0017] The piston in each cylinder is connected to a crankshaft via a connecting rod. The connecting rod is used to convert the reciprocating motion of the piston into the rotary motion of the crankshaft.

[0018] Thus, the internal combustion engine 2 is used to generate drive power for propelling the vehicle 1 by moving the piston back and forth within the cylinder due to the combustion of a fuel-air mixture of fuel and air in a combustion chamber 25 and by setting the crankshaft in rotation by the connecting rod.

[0019] An intake port of the engine 2 is equipped with an intake manifold 31 for introducing air into the combustion chamber 25. The intake manifold 31 is connected to an intake pipe 32 for drawing in outside air. This means that the intake manifold 31 connects the intake pipe 32 to the intake port of each cylinder.

[0020] An upstream section of the intake manifold 31 forms a pressure equalization reservoir for the temporary storage of air. This pressure equalization reservoir, corresponding to the upstream section of the intake manifold 31, is equipped with an intake pressure sensor 27. The intake pressure sensor 27 detects a pressure in the intake manifold 31 as boost pressure and transmits a detection signal to the ECU 3. The boost pressure is a pressure downstream of a throttle valve 33 of the intake manifold 32 and is changed depending on the degree of opening of the throttle valve 33, the engine speed, or similar factors.

[0021] The intake manifold 32 is equipped with the throttle valve 33 for adjusting the intake air quantity of the internal combustion engine 2. The throttle valve 33 is designed as an electronically controlled throttle valve and is used to adjust the intake air quantity of the internal combustion engine 2 when the throttle valve opening degree is controlled in response to a command signal from the ECU 3.

[0022] The throttle valve 33 is equipped with a throttle valve opening degree sensor 28 and the throttle valve opening degree sensor 28 detects the opening degree of the throttle valve 33 and transmits a throttle valve opening degree as a detection signal to the ECU 3.

[0023] If the direction in which fresh air is introduced into the intake line 32 is designated as the intake direction, then an airflow sensor 21 is provided on the upstream side of the throttle valve 33 in the intake direction. The airflow sensor 21 detects the flow rate of the air flowing into the combustion engine 2.

[0024] An exhaust port of the internal combustion engine 2 is equipped with an exhaust manifold 41 to discharge exhaust gases produced by the combustion of the fuel-air mixture in the combustion chamber 25 from the vehicle. The exhaust manifold 41 is connected to the exhaust pipe 42. This means that the exhaust manifold 41 connects the exhaust pipe 42 to the exhaust port of each cylinder.

[0025] The exhaust pipe 42 is equipped with a three-way catalytic converter 43 and oxygen sensors 44 and 45, and a heater. The three-way catalytic converter 43 is used to clean exhaust gases, i.e., the combusted gases discharged from the combustion chamber 25 of the internal combustion engine 2.

[0026] If, in this context, the direction in which the exhaust gases are discharged is referred to as the exhaust direction, then the oxygen sensor 44 is provided on the upstream side of the three-way catalyst 43 in the exhaust direction. Furthermore, the oxygen sensor 45 is provided on the downstream side of the three-way catalyst 43 in the exhaust direction.

[0027] Oxygen sensors 44 and 45 detect whether the air-fuel ratio, in relation to the stoichiometric air-fuel ratio, is rather rich or lean by detecting an oxygen concentration in the exhaust gases and transmit a detection signal to the ECU 3.

[0028] Each of the oxygen sensors 44 and 45 is designed as a sensor that has an output characteristic where an output suddenly changes when the air-fuel ratio, with respect to the stoichiometric air-fuel ratio, becomes rich or lean, or as a sensor that has a linear output characteristic with respect to the oxygen concentration.

[0029] A fuel tank 51 stores gasoline as fuel for the internal combustion engine 2 at normal pressure. The gasoline stored in the fuel tank 51 is supplied under pressure by the fuel pump 51A, further pressurized by a high-pressure fuel pump 55, and injected into the combustion chamber 25 of each cylinder by an injector nozzle 24.

[0030] The internal combustion engine 2 includes a variable valve timing mechanism 26 on the intake side and is capable of adjusting intake timing by being controlled by the ECU 3. Furthermore, the variable valve timing mechanism 26 can be provided on both the intake and exhaust sides. When the variable valve timing mechanism 26 is controlled by the ECU 3, the intake timing, exhaust timing, and valve overlap can be adjusted.

[0031] A container 52 for adsorbing the vaporized fuel is connected to the fuel tank 51. A vent line 53 is connected to the container 52, and the intake manifold 31 is connected to one end of the vent line 53, which is opposite the connection end of the vent line 53 on the container 52. The vaporized fuel adsorbed into the container 52, along with air as purge gas, is introduced into the intake manifold 31 through the vent line 53.

[0032] The vent line 53 is equipped with a vent valve 54. The vent valve 54 is designed as a vacuum switching valve, which is actuated by a vacuum and is opened and closed by the ECU 3. The ECU 3 controls the amount of purge gas introduced into the intake manifold 31 by controlling the opening and closing of the vent valve 54.

[0033] The internal combustion engine 2 is equipped with a turbocharger 60, which pressurizes an intake air using exhaust gases, a bypass channel 46, which is designed to bypass a turbine 60A of the turbocharger 60 so that exhaust gases flow through this channel, and a wastegate valve 65, which regulates the amount of exhaust gases flowing through the bypass channel 46.

[0034] The turbocharger 60 comprises the turbine 60A, which is located in the exhaust duct and a compressor 60B, which is located in the intake duct, and the rotation of the turbine 60A caused by the exhaust gases is transferred to the compressor 60B, so that the compressor 60B charges the intake air.

[0035] A vacuum pump 67, which generates a vacuum, is connected to the wastegate valve 65 via a vacuum line 68. The vacuum line 68 is equipped with a vacuum switching valve 66, and the vacuum switching valve 66 is controlled by the ECU 3.

[0036] When the vacuum switching valve 66 is opened by the ECU 3, the vacuum from the vacuum pump 67 is supplied to the wastegate valve 65 via the vacuum line 68, so that the wastegate valve 65 is closed.

[0037] The ECU 3 is designed as a computing unit that includes a central processing unit (CPU), a working memory (RAM), a read-only memory (ROM), a flash memory, an input port and an output port.

[0038] The ECU 3's ROM contains a program, along with various control integers, different maps, or similar data, that enables the control unit to operate as ECU 3. This means that when the CPU executes the program stored in the ROM, the computer unit functions as ECU 3.

[0039] In addition to the airflow sensor 21 and the oxygen sensors 44 and 45, various sensors, such as an accelerator pedal opening degree sensor 22, a crank angle sensor 23, a cam angle sensor 72, a coolant temperature sensor 73, and an upstream throttle valve intake pressure sensor 75, are connected to the input port of the ECU 3.

[0040] The accelerator pedal opening degree sensor 22 detects an accelerator pedal opening degree, which indicates an actuation amount of an accelerator pedal 22A, and transmits a detection signal to the ECU 3.

[0041] The crankshaft angle sensor 23 is used to detect the rotation angle of the crankshaft of the internal combustion engine 2. The ECU 3 is used to calculate the engine speed of the internal combustion engine 2 based on the measurement result provided by the crankshaft angle sensor 23.

[0042] The cam angle sensor 72 is used to detect the rotation angle of the camshaft of the internal combustion engine 2. The ECU 3 determines the cylinder based on the detection result provided by the cam angle sensor 72.

[0043] The coolant temperature sensor 73 detects the temperature of coolant flowing in the combustion engine 2 and transmits a detection signal to the ECU 3. The upstream throttle valve intake pressure sensor 75 detects an intake pressure upstream of the throttle valve 33 in the intake line 32 and transmits a detection signal to the ECU 3.

[0044] Various devices, such as the wastegate valve 65, the injector 24, the throttle valve 33, the vent valve 54 and a VVT oil control valve 71 are connected to the output port of the ECU 3.

[0045] The control modes for the wastegate valve 65 are known as a normal closing control and a normal opening control. The normal closing control refers to a control in which the charging process takes place when the opening degree of the wastegate valve is normally closed, and the opening degree of the wastegate valve is open at high engine speeds to prevent the boost pressure from increasing too much.

[0046] In contrast, normal opening control refers to a control system in which the charging process is not carried out when the opening degree of the wastegate valve is, in a normal case, in an open state, and the charging process is carried out when the opening degree of the wastegate valve is in a closed state when the engine speed or engine load increases in accordance with an increase in the opening degree of the accelerator pedal.

[0047] However, with normal opening control, there is a tendency for the response during acceleration from the non-charging range to the charging range, corresponding to an increase in the amount of throttle input 22A, to not reach the level of normal closing control, where the charging process is carried out independently of the degree of throttle input. Accordingly, a desired boost pressure cannot necessarily be achieved in the initial phase.

[0048] To improve responsiveness during acceleration, in the present embodiment, the turbine 6A is also set in rotation in a non-charging range, where the accelerator pedal opening degree is equal to or less than a predetermined accelerator pedal opening degree, such that no charging process takes place. In particular, the ECU 3 controls the wastegate valve 65 in the non-charging range, where the accelerator pedal opening degree is equal to or less than the predetermined accelerator pedal opening degree, to an opening degree that is close to the fully closed state with respect to the fully open state.

[0049] This means that if the accelerator pedal opening degree is in the non-charging range, where it is equal to or less than the predetermined opening degree of the accelerator pedal, the ECU 3 in the present embodiment controls the wastegate valve to an opening degree that is close to the closed state in relation to the fully open state.

[0050] In this context, the non-boosting range and the boosting range differ by the degree of accelerator pedal opening. The non-boosting range refers to a range of accelerator pedal opening in which the boost pressure is equal to or less than atmospheric pressure. The boosting range refers to a range of accelerator pedal opening in which the boost pressure is greater than atmospheric pressure.

[0051] In other words, a range without charging corresponds to the non-charging range, and a range with charging corresponds to the charging range. Furthermore, the predetermined accelerator pedal opening degree refers to the accelerator pedal opening degree that corresponds to the upper limit of the non-charging range.

[0052] In the present embodiment, when the accelerator pedal 22A is actuated in the non-charging range, the ECU 3 controls the wastegate valve 65 to an opening degree that is close to a fully open state, such that the turbine speed of the turbocharger 60 becomes equal to or less than a predetermined turbine speed. In this context, the predetermined turbine speed is a speed corresponding to the predetermined accelerator pedal opening degree and a speed at which boost pressure is reached immediately before the start of a charging process.

[0053] When the accelerator pedal 22A is actuated in the non-charging range, the ECU 3 further controls the wastegate valve 65 to an opening degree that is close to a closed state in relation to a fully open state, so that the opening degree of the wastegate valve 65, which corresponds to the predetermined accelerator pedal opening degree, increases with increasing engine speed.

[0054] Furthermore, if the accelerator pedal opening amount corresponds to a first accelerator pedal opening amount as a predetermined accelerator pedal opening degree, the ECU 3 sets the wastegate valve 65 to a first opening degree that corresponds to the first accelerator pedal opening degree.

[0055] Furthermore, if the accelerator pedal opening amount is less than a second accelerator pedal opening degree, which in turn is less than the first accelerator pedal opening amount, the ECU 3 controls the wastegate valve 65 in such a way that it assumes a fully closed state.

[0056] Furthermore, if the accelerator pedal opening degree is equal to or greater than the second accelerator pedal opening degree and less than the first accelerator pedal opening degree, the ECU 3 sets the opening degree of wastegate valve 65 to the second opening degree, which is less than the first opening degree and corresponds to the accelerator pedal opening degree. Since the second opening degree corresponds to the accelerator pedal opening degree, the opening degree is not a fixed value and is correlated with the accelerator pedal opening degree.

[0057] Since the intake and exhaust gas volumes increase with increasing accelerator pedal opening, causing a slight increase in turbine speed, the boost pressure also increases. In the present embodiment, the second opening degree is configured to increase in conjunction with the accelerator pedal opening degree. Accordingly, the problem of having to increase the turbine speed to a certain speed or more to initiate the boosting process in the non-boosted range can be avoided.

[0058] Furthermore, when the accelerator pedal 22A is depressed in the non-charging range, the ECU 3 can adjust the wastegate valve 65 to an opening degree that is close to a fully open state, so that the turbine speed of the turbocharger 60 is kept stable at the predetermined turbine speed in order to reach the boost pressure immediately before the start of the charging process in response to the predetermined accelerator pedal opening degree. Here, the predetermined turbine speed refers to a speed corresponding to the predetermined accelerator pedal opening degree and a speed that serves to reach the boost pressure immediately before the start of the charging process.

[0059] In the present embodiment, the wastegate valve opening amount is adjusted based on the degree of accelerator pedal opening. However, instead of the accelerator pedal opening amount, the wastegate valve opening amount can also be adjusted based on a torque requested by a driver, which results from parameters such as the fuel injection quantity, the ignition timing, and the intake quantity.

[0060] The following describes the operation of the previously described control device for an internal combustion engine according to the present embodiment with reference to the flowchart of the Fig. 2 described.

[0061] In Fig. Step 2 of the ECU determines whether the accelerator pedal opening degree is greater than the initial accelerator pedal opening value (step S1). Since the accelerator pedal opening degree is within the boost range if it is greater than the initial accelerator pedal opening value, the ECU performs a boost control operation (step S2) and terminates the current process. During boost control, the ECU 3 adjusts the accelerator pedal opening value to a degree at which boost pressure can be achieved.

[0062] As described below, in the present embodiment the wastegate valve opening degree is controlled such that it decreases as the accelerator pedal opening degree increases. Furthermore, the wastegate valve 65 is controlled such that, after the accelerator pedal opening degree has increased to a predetermined value, it is kept at a small opening degree.

[0063] If the accelerator pedal opening degree in step S1 is equal to or less than the first accelerator pedal opening degree, the ECU 3 determines whether the accelerator pedal opening amount is equal to or less than the first accelerator pedal opening degree and equal to or greater than the second accelerator pedal opening degree (step S3).

[0064] If the accelerator pedal opening amount in step S3 is equal to or less than the first accelerator pedal opening degree and equal to or greater than the second accelerator pedal opening amount, the ECU 3 sets the wastegate valve 65 (labeled WGV in the drawing) to the opening degree that corresponds to the accelerator pedal opening degree (step S4) and ends the current process.

[0065] If the accelerator pedal opening degree in step S3 is not equal to or less than the first accelerator pedal opening degree and not equal to or greater than the second accelerator pedal opening degree, the ECU 3 determines whether the accelerator pedal opening degree is less than the second accelerator pedal opening degree (step S5).

[0066] If the accelerator pedal opening degree in step S5 is less than the second accelerator pedal opening degree, the ECU 3 controls the wastegate valve 65 (labeled WGV in the drawing) in such a way that it reaches a fully closed state (step S6) and ends the current process.

[0067] If the accelerator pedal opening degree in step S5 is not less than the second accelerator pedal opening degree, the ECU 3 terminates the current process.

[0068] As a result, a process of Fig. 2 with reference to the time sequence diagram of the Fig. 3 described. The time sequence diagram shows a transition in the state of the vehicle during acceleration.

[0069] Fig. Figure 3 represents a transition of the accelerator pedal opening degree, the wastegate valve opening degree (referred to as WGV in the drawing) and the boost pressure.

[0070] Regarding the wastegate valve opening degree in the drawing, the opening degree (labeled as large Ne in the drawing) at a relatively high engine speed is represented by the dotted line, and the opening degree (labeled as small Ne in the drawing) at a relatively low engine speed is represented by the solid line. The wastegate valve opening degree at a relatively high engine speed is designed to be large compared to a relatively low engine speed. This is because the exhaust gas volume increases with increasing engine speed, and it is necessary to reduce the amount of exhaust gas flowing through turbine 60A to such an extent that the turbocharging process does not start.

[0071] In Fig. At time t0 of the initial state, the accelerator pedal opening degree is 0 and the wastegate valve opening degree is fully open. If, subsequently, at time t1, the accelerator pedal opening degree becomes slightly greater than 0, the wastegate valve opening degree is fully closed.

[0072] If, subsequently, at time t2, the accelerator pedal opening degree increases to the second accelerator pedal opening degree, the wastegate valve opening degree is opened from the fully closed state to the second opening degree (referred to as the second WGV opening degree in the drawing).

[0073] After that, the wastegate valve opening degree increases with increasing accelerator pedal opening degree.

[0074] If, at time t3, the accelerator pedal opening degree increases to the first opening degree, the wastegate valve 65 is set to the first opening degree (labeled as the first WGV opening degree in the diagram). Between time t2 and time t3, the wastegate valve opening degree is large when the engine speed is high and small when the engine speed is low. Thus, the wastegate valve opening degree corresponding to the predetermined accelerator pedal opening degree is controlled such that it increases with increasing engine speed. Furthermore, the second accelerator pedal opening degree, at which the wastegate valve opens from the fully closed state to the second opening degree, can be configured to be small with increasing engine speed.In this case, because the exhaust gas volume from the combustion engine increases with increasing engine speed, the amount of exhaust gas flowing through turbine 60A can be regulated by opening the wastegate valve at an early stage. Accordingly, it can be prevented that the turbine speed becomes equal to or higher than the speed at which the turbocharging process begins.

[0075] In the charging phase after time t3, the wastegate valve opening is controlled such that it decreases as the accelerator pedal opening increases. Furthermore, wastegate valve 65 is controlled such that, after the accelerator pedal opening has increased to a predetermined value, it is held at a small opening (for example, 10%).

[0076] An example is a case in which the wastegate valve is held at a small opening degree of, for example, 10%, and the wastegate valve opening degree can be controlled to be held at 0 (a completely closed state). This means that as the accelerator pedal opening degree increases to the predetermined accelerator pedal opening degree, the wastegate valve opening degree is not limited to a small opening degree such as 10%, but can also be equal to 0. In the present embodiment, with respect to the opening degree of the wastegate valve 65, an opening degree of 0 and a small opening degree of 10% or the like are generally referred to as a closed state.

[0077] Furthermore, at time t0 of the initial state, the accelerator pedal opening is zero, and the wastegate valve opening is controlled to assume a fully open state. Subsequently, when the accelerator pedal opening becomes slightly greater than zero, the wastegate valve opening is controlled to a fully closed state. However, the wastegate valve opening can be set to a fully closed state when the accelerator pedal opening is zero. In this case, because the exhaust gases flow through turbine 60A from an accelerator pedal opening of zero, the turbocharging process can be started at an earlier time.

[0078] The following describes the control of the opening and closing process of the wastegate valve with reference to the timing diagram of the Fig. 4 described. Fig. Figure 4 shows how the wastegate valve 65 transitions from an opening degree of 0 to an open state and back to an opening degree of 0.

[0079] A transition at the time of opening of the wastegate valve 65 in the time sequence diagram corresponds to a transition in the wastegate valve opening degree of the Fig. 3 from time t1 to time t3. The solid line denotes a transition of the present embodiment, and the dashed line denotes a transition of the comparison example.

[0080] Since in Fig. 4, at time t10 of the initial state, the (not shown) accelerator pedal opening degree is smaller than the second accelerator pedal opening degree of the Fig. When 3 is selected, the wastegate valve opening degree is set to 0 (a closed state).

[0081] Since the accelerator pedal opening degree subsequently increases from time t11 to the second accelerator pedal opening degree of the Fig. As the 3 increases, the wastegate valve opening degree is opened up to the opening degree that corresponds to the second opening degree.

[0082] Subsequently, at time t12, the accelerator pedal opening degree is opened to the fully open state, and the wastegate valve opening degree is also opened to a large degree corresponding to the accelerator pedal opening degree.

[0083] Subsequently, at time t13, the accelerator pedal opening degree is set to a small degree and the wastegate valve opening degree is also set to a small degree.

[0084] Subsequently, because at time t14 the accelerator pedal opening amount reaches the second accelerator pedal opening degree of the Fig. 3 decreases, the wastegate valve opening amount is set to 0 (a fully closed state).

[0085] In this embodiment, a tiny opening degree is skipped during the opening and closing of the wastegate valve 65. Since it is now possible to prevent the problem of a tiny opening degree of the wastegate valve 65, it is correspondingly possible to prevent an impact noise (also called rattling) of the wastegate valve 65 in the case of a tiny opening degree.

[0086] As previously described, in the present embodiment, the ECU 3 controls the wastegate valve 65 in the non-charging range, in which the accelerator pedal opening degree is equal to or less than the predetermined accelerator pedal opening degree, to an opening degree that is close to a state with respect to a fully open state.

[0087] Accordingly, if the wastegate valve 65 is controlled in the non-charging range, where the accelerator pedal opening is equal to or less than the predetermined accelerator pedal opening, to an opening degree close to a fully open state, the exhaust gases can be fed to the turbine 60A. Therefore, it is possible to set the turbine 60A in rotation without the need for supercharging in the non-charging range.

[0088] Since it is possible to achieve a desired boost pressure at an early stage during the transition from the non-charging range to the charging range in accordance with an increase in the amount of actuation of the accelerator pedal 22A, it is possible to improve the response during acceleration.

[0089] Furthermore, according to the present embodiment, the ECU 3 controls the wastegate valve 65 to an opening degree that is close to a closed state with respect to a fully open state, so that the speed of the turbocharger 60 becomes equal to or less than the predetermined turbine speed at which the boost pressure is reached immediately before the start of the charging process, in response to the predetermined accelerator pedal opening amount when the accelerator pedal 22A is actuated in the non-charging range.

[0090] Accordingly, the predetermined accelerator pedal opening degree in the non-charging range corresponds to a state immediately before the start of the charging process, and the turbine 60A can rotate to such an extent that no charging process takes place in this state. Thus, it is possible to achieve the desired boost pressure at an early stage when transitioning into the charging range.

[0091] Since the turbine 60A can be rotated to such an extent that no charging process takes place in the non-charging range, it is possible to achieve a desired boost pressure at an early stage of the transition from the non-charging range to the charging range in accordance with an increase in the actuation amount of the accelerator pedal 22A and thus improve the response during acceleration.

[0092] Furthermore, if the accelerator pedal opening amount, according to the present embodiment, corresponds to a predetermined accelerator pedal opening degree, the ECU 3 sets the wastegate valve 65 to the first opening degree, which corresponds to the first accelerator pedal opening degree. If, furthermore, the accelerator pedal opening amount is less than the second accelerator pedal opening degree, which in turn is less than the first accelerator pedal opening amount, the ECU 3 controls the wastegate valve 65 such that it assumes a fully closed state. If, furthermore, the accelerator pedal opening degree is equal to or greater than the second accelerator pedal opening degree and less than the first accelerator pedal opening degree, the ECU 3 sets the opening degree of the wastegate valve 65 to the second opening degree, which is less than the first opening degree and corresponds to the accelerator pedal opening degree.

[0093] Since the opening degree of the wastegate valve 65 is set to 0, and the wastegate valve is set to a fully closed state in a range where the accelerator pedal opening degree is less than the second accelerator pedal opening degree, it is accordingly possible to actively drive the turbine 60A by the exhaust gases. For this reason, the driver can achieve the desired acceleration when the accelerator pedal 22A is pressed.

[0094] Since the opening degree of the wastegate valve 65 is set to the second opening degree that corresponds to the accelerator pedal opening degree in the range of the second accelerator pedal opening degree or more, it is possible to improve the controllability of the wastegate valve 65.

[0095] Since the wastegate valve 65 changes from opening degree 0 to the second opening degree when the accelerator pedal opening degree increases from 0 and reaches the second accelerator pedal opening degree or more, it is possible to prevent the problem of a tiny opening degree of the wastegate valve 65 close to the fully closed state and to prevent rattling of the wastegate valve 65 at the tiny opening degree.

[0096] Furthermore, according to the present embodiment, the ECU 3 controls the wastegate valve 65 to an opening degree that is close to a closed state with respect to a fully open state, so that the turbine speed matches the predetermined turbine speed at which the boost pressure is reached immediately before the start of the charging process, in response to the predetermined accelerator pedal opening degree when the accelerator pedal 22A is actuated in the non-charging range.

[0097] Since the boost pressure is kept constant immediately before the start of the charging process with the predetermined turbine speed, which corresponds to the predetermined accelerator pedal opening degree in the non-charging range, it is possible in this way to achieve a desired boost pressure at an early point in the transition from the non-charging range to the charging range in accordance with an increase in the actuation amount of the accelerator pedal 22A, and thus to improve the response during acceleration.

[0098] When the accelerator pedal 22A is actuated in the non-charging range, the ECU 3 according to the present embodiment also controls the wastegate valve 65 to an opening degree which is close to a closed state with respect to a fully open state, so that the opening degree of the wastegate valve 65 corresponding to the predetermined accelerator pedal opening degree increases with increasing engine speed.

[0099] Since the intake and exhaust gas volumes increase with increasing engine speed, it is accordingly possible to prevent an excessive increase in engine speed at the time of transition from the non-charged range to the charged range.

[0100] Although embodiments of the present invention have been described here, it is obvious to the person skilled in the art that modifications can be made without departing from the principle of the present invention. All possible modifications and equivalents are to be considered as covered by the appended claims.

Claims

Internal combustion engine control device for an internal combustion engine (2) comprising: a turbocharger (60) pressurizing intake air using exhaust gases from an internal combustion engine (2), a bypass channel (46) configured to bypass a turbine (60A) of the turbocharger (60) so that exhaust gases flow through this channel, and a wastegate valve (65) regulating the amount of exhaust gases flowing through the bypass channel (46), wherein the internal combustion engine control device comprises: a control unit (3) performing normal opening control to close the wastegate valve (65) in accordance with an increase in the degree of opening of an accelerator pedal (22A), wherein the control unit (3) in a non-charged range, within which the degree of opening of the accelerator pedal is equal to or less than a first degree of opening of the accelerator pedal, opens the wastegate valve (65) to a degree of opening controlswhich is close to a fully open state with respect to a fully open state, and wherein in the non-charging range, the control unit (3): controls the wastegate valve (65) to a first degree of opening corresponding to the first accelerator pedal opening degree when the accelerator pedal opening amount corresponds to a predetermined accelerator pedal opening degree; controls the wastegate valve (65) to a fully closed state when the accelerator pedal opening degree is less than a second accelerator pedal opening degree, which in turn is less than the first accelerator pedal opening degree; and controls the degree of opening of the wastegate valve (65) to a second degree of opening that is less than the first degree of opening and corresponds to the accelerator pedal opening degree when the accelerator pedal opening degree is equal to or greater than the second accelerator pedal opening degree and less than the first accelerator pedal opening degree. Internal combustion engine control device according to claim 1, wherein, when the accelerator pedal (22A) is actuated in the non-charging range, the control unit (3) controls the wastegate valve (65) to an opening degree which is close to a closed state with respect to a fully open state, so that, in response to the first accelerator pedal opening degree, a turbine speed of the turbocharger (60) becomes equal to or less than a predetermined turbine speed at which a boost pressure is reached immediately before the start of a charging process. Internal combustion engine control device according to claim 1 or 2, wherein, when the accelerator pedal (22A) is actuated in the non-charging range, the control unit (3) controls the wastegate valve (65) to an opening degree which is close to a closed state with respect to a fully open state, so that the turbine speed is maintained at a predetermined turbine speed at which, in response to the first accelerator pedal opening amount, the boost pressure is reached immediately before the start of the charging process. Internal combustion engine control device according to claim 1 or 2, wherein, when the accelerator pedal (22A) is actuated in the non-charging range, the control unit (3) controls an opening degree of the wastegate valve (65) such that it increases with increasing engine speed.

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