Internal combustion engine control system

Abstract

To provide an internal combustion engine control system capable of efficiently operating an internal combustion engine by combining control of a waste gate valve and control of a rotary electric machine in accordance with a state of a vehicle.SOLUTION: An internal combustion engine control system includes a turbine through which exhaust gas of an internal combustion engine mounted on a vehicle flows, a compressor which is disposed coaxially with the turbine and supercharges intake air of the internal combustion engine, a rotary electric machine which rotates the turbine and the compressor, a waste gate valve which releases the exhaust gas flowing through the turbine, and a control device for controlling the rotary electric machine and the waste gate valve. The control device controls the waste gate valve to be in an open state and increases rotation speed of the rotary electric machine when the vehicle is accelerated at predetermined acceleration or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to control systems for internal combustion engines. [Background technology]

[0002] Conventionally, an electric supercharger in which a motor (rotating electric machine) is attached to a supercharger having a turbine and a compressor has been known (see, for example, Patent Document 1 and Patent Document 2). In such an electric supercharger, the rotating electric machine assists the rotation of the turbine and controls the rotation speed of the turbine.

[0003] Patent Document 1 discloses an internal combustion engine control system that controls a rotating electric machine by regenerative control using exhaust energy recovered by a turbine in an internal combustion engine using such an electric supercharger. Patent Document 2 discloses an internal combustion engine control system that increases the output of the internal combustion engine when generating electricity using the rotating electric machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-83222 A [Patent Document 2] JP 2004-169673 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such an electric turbocharger, it is preferable to control a wastegate valve that adjusts the exhaust energy flowing to the turbine in combination with the power running or regeneration of the motor. Patent Documents 1 and 2 do not disclose this point.

[0006] An object of the present disclosure is to provide an internal combustion engine control system that can efficiently operate an internal combustion engine by combining control of a wastegate valve and control of a rotating electric machine depending on the state of the vehicle. [Means for solving the problem]

[0007] The present disclosure relates to a control system for an internal combustion engine, the control system including a turbine through which exhaust gas from an internal combustion engine mounted on a vehicle flows, a compressor arranged coaxially with the turbine and for supercharging an intake air of the internal combustion engine, a rotating electric machine for rotating the turbine and the compressor, a wastegate valve for releasing the exhaust gas flowing to the turbine, and a control device for controlling the rotating electric machine and the wastegate valve. When the vehicle is accelerated at a predetermined acceleration or more, the control device controls the wastegate valve to an open state and increases the rotation speed of the rotating electric machine.

[0008] According to this internal combustion engine control system, when the vehicle accelerates at or above a predetermined acceleration, the control device opens the wastegate valve instead of fully closing it, and assists the turbine speed increase with the rotating electric machine. This makes it possible to suppress the occurrence of internal exhaust gas recirculation (internal EGR). As a result, according to this internal combustion engine control system, the control device can operate the internal combustion engine efficiently. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an internal combustion engine control system that can operate the internal combustion engine efficiently by combining control of the wastegate valve and control of the rotating electric machine depending on the state of the vehicle. [Brief description of the drawings]

[0010] [Figure 1] 1 is a system diagram of an internal combustion engine control system according to an embodiment of the present disclosure. [Diagram 2] 4 is a flowchart showing a control procedure of a control device according to an embodiment of the present disclosure. [Diagram 3] 3 is a graph showing the output (torque) and rotation speed of an internal combustion engine according to an embodiment of the present disclosure. [Figure 4]4 is a timing chart showing the turbine rotation speed, the opening degree of the wastegate valve, and the operating state of the motor generator during acceleration of a vehicle according to an embodiment of the present disclosure. [Diagram 5] 4 is a table showing an example of a relationship between the opening degree of a wastegate valve and the output of a motor generator according to a state of a vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] As shown in FIG. 1, the internal combustion engine control system 1 includes an engine (an example of an internal combustion engine) 2, a turbine 4, a compressor 6, a motor generator (an example of a rotating electric machine) 8, a wastegate valve 10, an electricity storage device 12, a throttle valve 14, an accelerator position sensor 16, an exhaust purification device 18, and a control device 20.

[0013] The internal combustion engine 2 of this embodiment is a reciprocating gasoline internal combustion engine mounted on a vehicle such as an automobile, and has a cylinder 2a, a piston 2b that slides in the cylinder 2a, an injector 2c that injects fuel, and an ignition plug 2d that ignites the air-fuel mixture. In this embodiment, the internal combustion engine 2 is an in-line internal combustion engine 2 in which the cylinders 2a are arranged in a row. Moreover, the internal combustion engine 2 of this embodiment is a direct injection type internal combustion engine in which fuel is directly injected into the cylinder 2a.

[0014] The turbine 4 is passed through by the exhaust gas discharged from the cylinder 2a of the internal combustion engine 2. The turbine 4 is covered by a turbine housing 4a, and is rotated by the exhaust gas energy flowing through the turbine housing 4a.

[0015] The compressor 6 is disposed on a rotating shaft 4b connected to the turbine 4. The compressor 6 is covered by a compressor housing 6a, and supercharges the intake air of the internal combustion engine 2 supplied from an air cleaner 22 to the compressor housing 6a. The downstream side of the compressor 6 is connected to an intake passage 24 which is connected to an intake port of the internal combustion engine 2. An intercooler 26 is disposed on the intake passage 24 to cool the supercharged intake air. A throttle valve 14 is disposed downstream of the intercooler 26 in the intake passage 24. The throttle valve 14 is electrically connected to a control device 20 and controls the amount of intake air supplied to the internal combustion engine 2.

[0016] The motor generator 8 has an output shaft connected to the rotating shaft 4b of the turbine 4, and rotates the turbine 4 and the compressor 6 by powering. In this embodiment, the rotating shaft 4b is the output shaft of the motor generator 8. The motor generator 8 has a regenerative circuit, and is capable of regenerating by applying a load to the regenerative circuit. The motor generator 8 can reduce the rotation speed of the turbine 4 and the compressor 6 by regenerating. Furthermore, the motor generator 8 can generate power without reducing the rotation speed of the turbine 4 while the rotating shaft 4b is driven by the turbine 4. In other words, the motor generator 8 can recover exhaust energy by the turbine 4 and generate power. In this specification, regeneration for the purpose of reducing the turbine rotation speed is referred to as regeneration. Regeneration for the purpose of charging the power storage device 12 is referred to as power generation.

[0017] The motor generator 8 is electrically connected to the power storage device 12. When the motor generator 8 is powered, the power storage device 12 discharges power and supplies power to the motor generator 8. On the other hand, when the motor generator 8 regenerates and generates power, the power storage device 12 receives and stores power. In this embodiment, the power storage device 12 is formed of a lithium ion battery, a NiCad battery, or the like. However, the power storage device 12 may be any device that can store and discharge power, and may be, for example, a capacitor.

[0018] The wastegate valve 10 is a device that adjusts the amount of exhaust gas flowing to the turbine 4. Specifically, a wastegate passage 10a is provided that bypasses the turbine 4 from the turbine housing 4a and is connected to the exhaust passage 28, and the wastegate valve 10 is a valve that opens and closes the wastegate passage 10a. The wastegate valve 10 is used to increase or decrease the turbine speed Tr of the turbine 4 by adjusting the amount of exhaust gas flowing to the turbine 4. When the turbine speed Tr of the turbine 4 changes, the boost pressure Pr increases or decreases. Therefore, the boost pressure Pr can be controlled by controlling the opening degree W of the wastegate valve 10 (referred to as W / G opening degree in Figs. 2, 4, and 5). The wastegate valve 10 of this embodiment is an electromagnetic valve that opens and closes the valve by an electric actuator. In addition, the wastegate valve 10 of this embodiment is a normally open type wastegate valve 10 that opens the wastegate passage 10a when not controlled.

[0019] The control device 20 controls the motor generator 8 and the wastegate valve 10 in accordance with the state of the vehicle, and controls the turbine speed Tr of the turbine 4. In this embodiment, the control device 20 detects the accelerator opening Th from the accelerator position sensor 16 attached to the accelerator pedal 16a, and controls each device of the control system of the internal combustion engine 2, such as the injector 2c, the motor generator 8, and the wastegate valve 10, in accordance with the accelerator opening Th. The control device 20 is actually an ECU (Electronic Control Unit) configured by a microcomputer including a calculation device, a memory, an input / output buffer, and the like. The control device 20 controls each device so that the internal combustion engine 2 is in a desired operating state based on a map and a program stored in the memory. Note that the various controls are not limited to being processed by software, and can also be processed by dedicated hardware (electronic circuits).

[0020] More specifically, the control device 20 of this embodiment acquires the accelerator opening degree Th, and determines a required output ETq required of the internal combustion engine 2 and a target boost pressure Pt corresponding to the required output ETq. The control device 20 acquires an actual boost pressure Pr from an atmospheric pressure sensor 32 attached to the air cleaner 22 and a pressure sensor 34 attached to the intake passage 24, and executes control of the power running and regeneration of the motor generator 8 and control of the opening degree W of the wastegate valve 10 so that the boost pressure Pr becomes the target boost pressure Pt. The control device 20 controls the turbine rotation speed Tr of the turbine 4 by controlling the motor generator 8 and the wastegate valve 10 in this manner.

[0021] The accelerator opening degree Th is an example of the state of the vehicle. The state of the vehicle may also be the acceleration or deceleration state of the vehicle obtained from an acceleration sensor (not shown).

[0022] Next, a control procedure executed by the control device 20 will be described with reference to the flowchart of Fig. 2 and Fig. 3 and Fig. 4. The control device 20 starts the control procedure when an ignition switch (not shown) is turned on.

[0023] In step S1, the control device 20 detects the accelerator opening Th. When the control device 20 detects the accelerator opening Th, the process proceeds to step S2. In step S2, the control device 20 judges whether the acceleration of the vehicle is equal to or greater than a predetermined acceleration. In this embodiment, the control device 20 judges whether the acceleration is equal to or greater than the predetermined acceleration based on the accelerator opening Th. For example, when the accelerator opening Th is 70% or more, the control device 20 judges that the acceleration is equal to or greater than the predetermined acceleration. As shown by the arrow A in FIG. 3, when the accelerator opening Th is 70% or more, the control device 20 operates the internal combustion engine 2 in a high load region (near the maximum output) of the internal combustion engine 2. At this time, in the low-medium rotation high load region, the control device 20 controls the valve opening and closing timing of the intake valve 36 and the exhaust valve 38, and executes valve overlap control that controls so that the opening periods of the intake valve 36 and the exhaust valve 38 overlap. The control device 20 may judge whether the acceleration is equal to or greater than the predetermined acceleration based on the required output ETq required of the internal combustion engine 2 or the target boost pressure Pt. When the control device 20 determines that the acceleration is equal to or greater than the predetermined acceleration (YES in step S2), the process proceeds to step S3.

[0024] In step S3, the control device 20 powers the motor generator 8 to increase the rotation of the motor generator 8. Specifically, the control device 20 determines a target boost pressure Pt according to the accelerator opening Th, and powers the motor generator 8 to increase the rotation speed Mr of the motor generator 8 corresponding to the target boost pressure Pt. After powering the motor generator 8, the control device 20 proceeds to the process of step S4.

[0025] In step S4, the controller 20 controls the wastegate valve 10 from the fully open state to the closing direction (closing direction). As shown by the solid line in the opening degree W of the wastegate valve 10 from time t1 to time t2 in Fig. 4, the controller 20 does not completely close the wastegate valve 10. In other words, the controller 20 changes the opening degree W of the wastegate valve 10 from the large opening degree in the fully open state to the small opening degree in a slightly open state.

[0026] As shown by the broken line from time t1 to time t2 in FIG. 4, the conventional wastegate valve 10 is in a fully closed state at this time. In this way, the rotation speed of the turbine 4 (turbine rotation speed Tr) is increased by fully closing the wastegate valve 10. However, in the control system 1 of the internal combustion engine 2 of this embodiment, the motor generator 8 is powered as shown by the solid line from time t1 to time t2 in FIG. 4, and the opening degree W of the wastegate valve 10 is controlled in the closing direction. As a result, the turbine rotation speed Tr is increased with the assistance of the motor generator 8, while the increase in exhaust pressure is suppressed. As a result, the occurrence of internal exhaust gas recirculation (internal EGR) that flows back from the turbine housing 4a to the cylinder 2a can be suppressed. Therefore, the combustion state of the internal combustion engine 2 is improved, and the output of the internal combustion engine 2 is likely to be improved. Furthermore, in the low-medium rotation high load region, the control device 20 executes valve overlap control. As a result, the internal EGR can be suppressed while improving the output of the internal combustion engine 2 by inertia supercharging, and the output of the internal combustion engine 2 is likely to be further improved.

[0027] Furthermore, according to the control system 1 for the internal combustion engine 2, the responsiveness of the boost pressure is improved, and the output responsiveness of the internal combustion engine 2 with respect to the accelerator opening Th is increased. As a result, the drivability of the vehicle is improved. After controlling the wastegate valve 10 in the closing direction, the control device 20 proceeds to step S5.

[0028] In step S5, the control device 20 judges whether the vehicle maintains acceleration. The case where the vehicle maintains acceleration is, for example, a state where the internal combustion engine 2 is further loaded due to climbing a slope while accelerating in the state of arrow A in FIG. 3. That is, the case where the accelerator opening Th is increased by the user further depressing the accelerator pedal 16a, or the control device 20 increases the accelerator opening Th during cruise control. In this embodiment, for example, the case where the accelerator opening Th is increased from 70% to 100%.

[0029] When the control device 20 determines in step S5 that the vehicle maintains acceleration (step S5 YES), the control device 20 controls the wastegate valve 10 from an open state to a closed state. In this embodiment, the control device 20 fully closes the wastegate valve 10 (step S6). More specifically, as shown from time t3 to time t4 in FIG. 4, the control device 20 controls the wastegate valve 10 from a small opening degree to a fully closed state. However, the opening degree W of the wastegate valve 10 may be determined based on the target boost pressure Pt. Furthermore, as shown from time t4 to time t5 in FIG. 4, when the acceleration state is further maintained despite the wastegate valve 10 being fully closed, the control device 20 powers the motor generator 8 to increase the rotation of the motor generator 8 and assists the increase in the turbine rotation speed Tr.

[0030] In this case, the turbine speed Tr rotates at, for example, 150,000 to 200,000 rpm. In this range of turbine speed Tr, a large amount of power is consumed when assisting the motor generator 8 to increase the turbine speed Tr. For this reason, it is preferable to control the boost pressure Pr by the wastegate valve 10. However, if the acceleration maintenance state continues and the required output ETq and the target boost pressure Pt continue to increase, the control device 20 assists the motor generator 8 in increasing the turbine speed Tr even though it consumes power. This improves drivability.

[0031] After executing the process of step S6, the control device 20 advances the process to step S1. If the control device 20 determines in step S5 that the accelerating state is not maintained, the control device 20 advances the process to step S1.

[0032] When the control device 20 determines in step S2 that the acceleration of the vehicle is less than the predetermined value (step S2 NO), the process proceeds to step S7, where the control device 20 determines whether the required output ETq is less than a predetermined required output (an example of less than the predetermined value). That is, the control device 20 determines whether the vehicle is in a state where it is not accelerating. The predetermined required output may be the value of the required output ETq in a state where the vehicle is not accelerating. The acceleration of the vehicle being less than the predetermined value also includes a case where the vehicle is accelerated at a speed less than the predetermined acceleration from a state where the vehicle is accelerated at a speed less than the predetermined acceleration. When the control device 20 determines in step S7 that the required output ETq is greater than the predetermined required output (step S7 YES), the process proceeds to step S8. In other words, when the control device 20 determines that the vehicle is in a state where the vehicle is accelerating at a speed less than the predetermined acceleration, the process proceeds to step S8. In this embodiment, whether the acceleration is less than the predetermined acceleration is determined by the accelerator opening Th. For example, when the accelerator opening Th is less than 70%, the control device 20 determines that the acceleration is less than the predetermined acceleration. 3, when the accelerator opening degree Th is less than 70%, the control device 20 operates the internal combustion engine 2 in a low to medium load region of the internal combustion engine 2. Note that the control device 20 may determine whether the acceleration is less than a predetermined acceleration based on a required output ETq required of the internal combustion engine 2 or a target boost pressure Pt.

[0033] In step S8, the control device 20 executes control to maintain the wastegate valve 10 in an open state when the vehicle is accelerated at less than a predetermined acceleration. In this embodiment, the control device 20 executes control to maintain the wastegate valve 10 between a medium opening and a fully open state. In such a low to medium load region of the internal combustion engine 2, the control device 20 controls the internal combustion engine 2 with the target boost pressure Pt low. Therefore, it is preferable that the control device 20 opens the wastegate valve 10 as much as possible to suppress the generation of internal EGR. This can improve the combustion state of the internal combustion engine 2. After the control device 20 controls the wastegate valve 10 to an open state, the process proceeds to step S9.

[0034] In step S9, the control device 20 suppresses the powering of the motor generator 8. In the low to medium load region, it is preferable that the control device 20 suppresses the powering of the motor generator 8 to suppress power consumption. Note that the control device 20 may execute steps S8 and S9 simultaneously.

[0035] In step S7, when the control device 20 determines that the required output ETq is less than the predetermined required output (step S7 NO), the process proceeds to step S10, where the control device 20 determines whether or not warming up of the exhaust purification device 18 is necessary. The control device 20 may determine whether or not warming up of the exhaust purification device 18 is necessary based on whether the coolant temperature Tw of the internal combustion engine 2 is a predetermined temperature (for example, 40 degrees or less). The control device 20 may also determine whether or not warming up of the exhaust purification device 18 is necessary by acquiring or estimating the temperature of the exhaust purification device 18. In any case, when the control device 20 determines that activation of the catalyst installed in the exhaust purification device 18 is necessary, it determines that warming up of the exhaust purification device 18 is necessary.

[0036] In step S10, if the control device 20 determines that the exhaust purification device 18 needs to be warmed up (YES in step S10), the process proceeds to step S11, where the control device 20 executes control to maintain the wastegate valve 10 in an open state. Furthermore, the control device 20 proceeds to step S12, where the motor generator 8 is powered. The control device 20 may execute steps S11 and S12 simultaneously. This causes the exhaust gas discharged from the wastegate passage 10a and the exhaust gas discharged from the turbine housing 4a to mix together, generating turbulence in the exhaust gas. As a result, the exhaust purification device 18 is more likely to be warmed up.

[0037] After executing the process of step S12, the control device 20 advances the process to step S1. If the control device 20 determines that the exhaust purification device 18 does not need to be warmed up (NO in step S10), the control device 20 advances the process to step S1. The control device 20 repeatedly executes such a process at predetermined intervals.

[0038] The control device 20 may control the wastegate valve 10 to the closing side and reduce the output of the motor generator 8 as the charging rate SOC (an example of power) of the power storage device 12 decreases.

[0039] For example, as shown in Fig. 5, when the vehicle is in a state of high acceleration (for example, when the acceleration is equal to or greater than a predetermined value in step S2), and the charging rate SOC is low (for example, less than 60%), the control device 20 may reduce the opening W of the wastegate valve 10 compared to when the charging rate SOC is high (for example, 60% or more) (for example, the opening W reduced in step S4). At this time, the control device 20 may reduce the motor output Mtq. This allows the control device 20 to compensate for the decrease in turbine speed Tr that accompanies the decrease in motor output Mtq by controlling the opening W of the wastegate valve 10, while suppressing the power consumption of the power storage device 12.

[0040] Similarly, when the acceleration is small (for example, less than a predetermined acceleration in step S2 and equal to or greater than a predetermined required output in step S7), the opening W of the wastegate valve 10 may be made smaller than the large opening, and the motor output Mta may be reduced. Note that even when acceleration is maintained (YES in step S5), if the opening W is slightly open rather than fully closed, the control device 20 may fully close the valve and reduce the motor output Mtq. On the other hand, when the charging rate SOC is small, the control device 20 may prohibit the motor generator 8 from warming up the exhaust purification device 18.

[0041] As described above, according to the control system 1 for the internal combustion engine 2 of the present disclosure, when the vehicle accelerates at or above a predetermined acceleration, the control device 20 assists the rise in the turbine speed by the motor generator 8 while opening the wastegate valve 10 instead of fully closing it. This makes it possible to suppress the occurrence of internal exhaust gas recirculation (internal EGR). As a result, according to the control system 1 for the internal combustion engine 2, the control device 20 can operate the internal combustion engine efficiently.

[0042] <Other embodiments> Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0043] (a) In the above embodiment, an example has been described in which the control device 20 controls all devices, but the present disclosure is not limited to this. A device that controls the motor generator 8 and a device that controls the other devices may be provided separately.

[0044] (b) In the above embodiment, the internal combustion engine 2 is described as a reciprocating gasoline internal combustion engine, but the present disclosure is not limited thereto. The internal combustion engine 2 may be a rotary internal combustion engine or a diesel internal combustion engine. In the present embodiment, the internal combustion engine 2 is described as an in-line internal combustion engine 2, but the internal combustion engine 2 may be a V-type or horizontally opposed internal combustion engine in addition to the in-line type. In addition, the internal combustion engine 2 in the present embodiment is described as a direct injection internal combustion engine, but the internal combustion engine 2 may be a multi-port type in which an injector 2c is arranged in the intake passage of each cylinder, a combined type of direct injection type and multi-port type, or a semi-direct injection type internal combustion engine 2. [Explanation of symbols]

[0045] 1: Control system 2: Internal combustion engine 4: Turbine 6: Compressor 10: Wastegate valve 12: Power storage device 18: Exhaust purification device 20: Control device

Claims

1. A turbine through which exhaust gas from an internal combustion engine mounted on a vehicle flows; a compressor arranged coaxially with the turbine and configured to supercharge the intake air of the internal combustion engine; a rotating electric machine that rotates the turbine and the compressor; a wastegate valve that releases exhaust gas flowing to the turbine; A control device that controls the rotating electric machine and the wastegate valve; Equipped with When the vehicle is accelerated at a predetermined acceleration or more, the control device controls the wastegate valve to an open state to increase the rotation speed of the rotating electric machine, When the vehicle is accelerated at a rate equal to or greater than the predetermined acceleration, the wastegate valve is controlled to be further opened while suppressing power running of the rotating electric machine. Control system for internal combustion engines.

2. The control device controls the wastegate valve from an open state to a closed state when the vehicle maintains an accelerating state, and powers the rotating electric machine.

2. The control system for an internal combustion engine according to claim 1.

3. An exhaust purification device that purifies exhaust gas from the internal combustion engine, When a required output of the vehicle is less than a predetermined value and when warming up of the exhaust purification device is required, the control device controls the wastegate valve to an open state and powers the rotating electric machine.

3. A control system for an internal combustion engine according to claim 1 or 2.

4. a power storage device for supplying power to the rotating electric machine, the control device controls the wastegate valve to a closing side and reduces an output of the rotating electric machine as the electric power of the power storage device decreases.

4. A control system for an internal combustion engine according to claim 1.

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