Engine control system

Abstract

To curb torque fluctuation when switching a valve to generate a swirl flow.SOLUTION: A system comprises: an engine including a valve which generates a swirl flow; a crank angle sensor; an acceleration sensor; and a control device. A storage media stores adjustment torque to control the engine when the valve is switched between an open position and a closed position. When determining that the valve is switched between the open position and the closed position, a processor: operates the engine based on the adjustment torque; determines whether or not rotation fluctuation after the engine is operated is within a first range based on the adjustment torque; determines whether or not acceleration fluctuation after the engine is operated is within a second range based on the adjustment torque; and corrects the adjustment torque based on the rotation fluctuation when the rotation fluctuation is not within the first range and the acceleration fluctuation is not within the second range.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an engine control system.

Background Art

[0002] In an engine, in order to stabilize the combustibility of an air-fuel mixture, a swirling flow may be generated in a combustion chamber. The swirling flow can be generated by a valve provided in an intake pipe. Specifically, when the valve is closed, the intake passage is thereby narrowed. With such a configuration, the flow rate of intake air is increased, and a swirling flow is generated in the combustion chamber. When the valve is opened, no swirling flow is generated. When the valve is switched between a closed position and an open position, the flow rate of intake air fluctuates rapidly. For this reason, the torque of the engine also fluctuates rapidly, which may lead to discomfort for the occupants. For example, Patent Document 1 discloses a control device for suppressing such torque fluctuations. This control device absorbs the above-described torque fluctuations by adjusting the fuel injection amount.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Torque fluctuations can vary depending on various factors. For this reason, even if the adjustment amount of fuel injection is determined based on several parameters, torque fluctuations may not be absorbed.

[0005] An object of the present invention is to provide an engine control system capable of suppressing torque fluctuations when switching a valve for generating a swirling flow.

Means for Solving the Problems

[0006] One aspect of the present invention is an engine including a valve that generates a swirling flow in a combustion chamber, a crank angle sensor that measures the rotational speed of the engine, an acceleration sensor that measures the acceleration of a vehicle on which the engine is provided, a control device that controls the engine, and is provided with the valve is operable between an open position and a closed position that generates the swirling flow, the control device includes one or more processors and one or more storage media that store instructions executed by the one or more processors, the one or more storage media store adjustment torque for controlling the engine when the valve is switched between the open position and the closed position, the one or more processors, according to the instructions, determine whether the valve has been switched between the open position and the closed position, when it is determined that the valve has been switched between the open position and the closed position, operate the engine based on the adjustment torque, after the engine is operated based on the adjustment torque, determine whether a rotational fluctuation obtained based on the rotational speed measured by the crank angle sensor is within a predetermined first range, after the engine is operated based on the adjustment torque, determine whether an acceleration fluctuation obtained based on the acceleration measured by the acceleration sensor is within a predetermined second range, when the rotational fluctuation is not within the first range and the acceleration fluctuation is not within the second range, correct the adjustment torque based on the rotational fluctuation, and is an engine control system configured to execute.

Advantages of the Invention

[0007] According to the present invention, torque fluctuations can be suppressed when switching a valve for generating a swirling flow.

Brief Description of the Drawings

[0008]

Figure 1

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in such embodiments are merely examples for easy understanding and do not limit the present invention unless otherwise specified. In the specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant description. Further, elements not directly related to the present invention are not shown.

[0010] FIG. 1 is a schematic diagram showing an engine control system 100 according to an embodiment of the present invention. The engine control system (which may also be simply referred to as the "system" in the present disclosure) 100 is applied to a vehicle 500 such as, for example, a HEV (Hybrid Electric Vehicle), a gasoline vehicle, or a diesel vehicle. The system 100 includes an engine 10.

[0011] In the present embodiment, the engine 10 is a gasoline engine. In other embodiments, the engine 10 may be a diesel engine. The engine 10 has a cylinder 11 and a piston 12. The piston 12 reciprocates within the cylinder 11. The combustion chamber 13 is defined by the cylinder 11 and the piston 12. The piston 12 is connected to the crankshaft 18 by a connecting rod 14.

[0012] In the engine 10 as described above, in the combustion chamber 13, a mixture of air and fuel burns, whereby the piston 12 reciprocates within the cylinder 11. The linear motion of the piston 12 is transmitted to the crankshaft 18 by the connecting rod 14 and converted into the rotational motion of the crankshaft 18. The rotational speed of the crankshaft 18, that is, the rotational speed of the engine 10, is measured by the crank angle sensor Se1. The crank angle sensor Se1 is communicably connected to an ECU 50 described later. For better understanding, only one set of the cylinder 11 and the piston 12 is shown in FIG. 1, but the engine 10 can have a plurality of sets of the cylinder 11 and the piston 12.

[0013] The engine 10 has an intake port 15 and an exhaust port 16. An intake valve 15a is provided in the intake port 15, and an exhaust valve 16a is provided in the exhaust port 16. The operation of each of the intake valve 15a and the exhaust valve 16a is controlled by, for example, a camshaft (not shown). The camshaft is rotated by a crankshaft 18 via, for example, a rotating belt or the like.

[0014] The engine 10 has a fuel injector 17. The injector 17 is provided in the combustion chamber 13, and fuel is injected from the injector 17 into the combustion chamber 13 (so-called direct injection). The injector 17 is communicably connected to the ECU 50. For example, the ECU 50 controls the injection amount of fuel from the injector 17 by controlling the lift of the needle valve of the injector 17.

[0015] The engine 10 has a spark plug P. The spark plug P is provided in the combustion chamber 13 and ignites the air-fuel mixture in the combustion chamber 13. The spark plug P is communicably connected to the ECU 50. The ECU 50 controls the operation of the spark plug P.

[0016] The intake port 15 is connected to the intake pipe 2 via an intake manifold M1. Components such as an air cleaner (not shown) are provided in the intake pipe 2, and the air that has passed through these components is supplied to the combustion chamber 13 through the intake port 15.

[0017] An air flow sensor Se2 is provided in the intake pipe 2. The air flow sensor Se2 measures the flow rate of the air flowing through the intake pipe 2. The air flow sensor Se2 is communicably connected to the ECU 50. For example, the ECU 50 controls at least one of the injector 17 or the throttle valve V1 based on the flow rate measured by the air flow sensor Se2.

[0018] In the intake pipe 2, a throttle valve V1 is provided downstream of the air flow sensor Se2. The throttle valve V1 adjusts the flow rate of the air flowing through the intake pipe 2. The throttle valve V1 is communicably connected to the ECU 50. The ECU 50 controls the intake air amount by controlling the throttle valve V1.

[0019] A tumble generator valve V2 is provided in a branch pipe 21 connecting the intake manifold M1 and the intake port 15. The tumble generator valve V2 is switchable between an open position and a closed position. In FIG. 1, the solid line indicates the open position of the tumble generator valve V2. In the open position, the flow path is the widest. In FIG. 1, the dashed line indicates the closed position of the tumble generator valve V2. In the closed position, the flow path is the narrowest. In the closed position, the flow velocity of the intake air is increased, thereby generating a tumble flow in the combustion chamber 13. The tumble generator valve V2 may also be switchable to an intermediate position between the open position and the closed position. In other embodiments, instead of the tumble generator valve V2, a swirl control valve (SCV) may be provided. The SCV forms a swirl flow in the combustion chamber 13. The tumble generator valve V2 is communicably connected to the ECU 50. The ECU 50 controls the operation of the tumble generator valve V2.

[0020] The exhaust port 16 is connected to the exhaust pipe 3 via the exhaust manifold M2. An air-fuel ratio (A / F) sensor Se3 is provided in the exhaust manifold M2. The A / F sensor Se3 measures the air-fuel ratio based on the exhaust gas flowing through the exhaust pipe 3. The A / F sensor Se3 is communicably connected to the ECU 50. For example, the ECU 50 controls at least one of the injector 17 or the throttle valve V1 based on the air-fuel ratio measured by the A / F sensor Se3.

[0021] System 100 includes an acceleration sensor Se4. The acceleration sensor Se4 measures the acceleration of the vehicle 500, that is, the rate of change of speed. For example, the acceleration sensor Se4 measures at least the acceleration of the vehicle 500 in the longitudinal direction. The acceleration sensor Se4 may further detect accelerations in other directions. The acceleration sensor Se4 may be provided at any position of the vehicle 500. For example, the acceleration sensor Se4 may be attached to the bottom of the driver's seat. The acceleration sensor Se4 is communicably connected to the ECU 50. For example, based on the acceleration measured by the acceleration sensor Se4, the ECU 50 controls at least one of the injector 17 or the throttle valve V1.

[0022] System 100 includes an ECU (control device) 50. The ECU 50 has one or more processors 51 (e.g., a CPU, etc.), one or more storage media 52 (e.g., a ROM and a RAM, etc.), and one or more connectors 53. The ECU 50 may further have other components. The components of the ECU 50 are communicably connected to each other by a bus. The storage media 52 stores one or more programs executed by the processor 51. The program includes instructions for the processor 51. The operations of the ECU 50 shown in the present disclosure are realized by the processor 51 executing the instructions stored in the storage media 52. The storage media 52 stores various maps T1 to T10 described later. Also, the storage media 52 stores the data received from the various sensors Se1 to Se4 described above. The ECU 50 is communicably connected to the components of the system 100 via the connector 53.

[0023] The engine 10 of the system 100 as described above is operable in lean burn. Lean burn operation uses an air-fuel mixture having a high air-fuel ratio compared to the stoichiometric air-fuel ratio (approximately 14.7). That is, in lean burn operation, an air-fuel mixture having a low fuel concentration is used. Therefore, in lean burn operation, a tumble flow is generated in the combustion chamber 13 by the tumble generator valve V2 in order to quickly mix the intake air and fuel and stabilize the combustibility of the air-fuel mixture. For example, lean burn operation is used in the low load and low speed region, and stoichiometric operation is used in the high load and high speed region. When switching from lean burn operation to stoichiometric operation, the tumble generator valve V2 is switched from the closed position to the open position. Symmetrically, when switching from stoichiometric operation to lean burn operation, the tumble generator valve V2 is switched from the open position to the closed position. When the tumble generator valve V2 is switched, the flow rate of the intake air fluctuates rapidly. For this reason, the torque of the engine 10 also fluctuates rapidly, which can lead to discomfort for the occupants. The system 100 is configured to suppress such torque fluctuations.

[0024] In this regard, the storage medium 52 stores the following maps T1 to T10. For example, the relationships shown in the maps T1 to T10 can be obtained by experiments or CAE (Computer-Aided Engineering).

[0025] Figure 2 shows the first base map T1 stored in the storage medium 52. In the first base map T1, the horizontal axis represents the rotational speed of the engine 10, and the vertical axis represents the load of the engine 10. In the present embodiment, the intake air amount is used as the load of the engine 10. In other embodiments, other parameters may be used as the load of the engine 10. The first base map T1 shows the MBT (Minimum Advance for Best Torque) of the ignition timing of the spark plug P according to the rotational speed and intake air amount of the engine 10. Each cell includes the MBT of the ignition timing corresponding to the rotational speed and intake air amount indicating the cell (not shown). The rotational speed is measured by the crank angle sensor Se1. The intake air amount is measured by the air flow sensor Se2. The processor 51 can determine the corresponding MBT of the ignition timing by referring to the first base map T1 together with the rotational speed and intake air amount. The processor 51 controls the ignition timing of the spark plug P based on the MBT of the ignition timing shown in the first base map T1 in both lean burn operation and stoichiometric operation.

[0026] Figure 3 shows the second base map T2 stored in the storage medium 52. Similar to the first base map T1 shown in FIG. 1, in the second base map T2, the horizontal axis represents the rotational speed of the engine 10, and the vertical axis represents the intake air amount of the engine 10. The second base map T2 shows the torque when the ignition timing is MBT shown in FIG. 1 according to the rotational speed and intake air amount of the engine 10. Each cell includes the torque corresponding to the rotational speed and intake air amount indicating the cell (not shown). The processor 51 estimates the torque of the engine 10 during operation by referring to the second base map T2 together with the rotational speed and intake air amount.

[0027] FIG. 4 is a first determination map T3 stored in the storage medium 52. In the first determination map T3, the horizontal axis indicates the rotational speed of the engine 10, and the vertical axis indicates the intake air amount of the engine 10. The first determination map T3 indicates a first threshold value of torque according to the rotational speed and intake air amount of the engine 10. Each cell includes a first threshold value corresponding to the rotational speed and intake air amount indicating the cell (not shown). For example, the first threshold value is the torque when the tumble generator valve V2 is switched from the closed position to the open position. Alternatively, for example, the first threshold value may be a value slightly lower than such torque. The processor 51 determines the corresponding first threshold value by referring to the first determination map T3 together with the rotational speed and intake air amount. The processor 51 determines whether the torque of the engine 10 estimated based on the second base map T2 in FIG. 3 is greater than the first threshold value determined based on the first determination map T4 in FIG. 4. According to such a configuration, the processor 51 can determine whether there is a high possibility that the tumble generator valve V2 is switched from the closed position to the open position.

[0028] FIG. 5 is a second determination map T4 stored in the storage medium 52. In the second determination map T4, the horizontal axis indicates the rotational speed of the engine 10, and the vertical axis indicates the intake air amount of the engine 10. The second determination map T4 indicates a second threshold value of torque according to the rotational speed and intake air amount of the engine 10. Each cell includes a second threshold value corresponding to the rotational speed and intake air amount indicating the cell (not shown). For example, at the torque indicated by the second threshold value, the tumble generator valve V2 has a low possibility of being switched from the closed position to the open position. For example, the second threshold value is a value lower than the first threshold value. The processor 51 can determine the corresponding second threshold value by referring to the second determination map T4 together with the rotational speed and intake air amount. The processor 51 determines whether the torque of the engine 10 estimated based on the second base map T2 in FIG. 3 is lower than the second threshold value determined based on the second determination map T4 in FIG. 5. According to such a configuration, the processor 51 can determine whether the tumble generator valve V2 maintains the closed position without being switched to the open position.

[0029] FIG. 6 is a preparatory map T5 stored in the storage medium 52. In the preparatory map T5, the horizontal axis indicates the rotational speed of the engine 10, and the vertical axis indicates the required torque. The preparatory map T5 indicates the throttle opening according to the rotational speed and the required torque of the engine 10. Each cell includes a throttle opening corresponding to the rotational speed and the required torque indicating the cell (not shown). For example, the required torque may be determined based on factors such as the depression amount of an accelerator pedal (not shown). The processor 51 determines the corresponding throttle opening by referring to the preparatory map T5 together with the rotational speed and the required torque. For example, the throttle opening shown in the preparatory map T5 is set so that a torque higher than the assumed required torque is output. The processor 51 controls the operation of the throttle valve V1 based on the throttle opening shown in the preparatory map T5 when the tumble generator valve V2 is switched from the closed position to the open position.

[0030] FIG. 7 is an ignition timing adjustment map T6 stored in the storage medium 52. In the ignition timing adjustment map T6, the horizontal axis indicates the retard angle of ignition, and the vertical axis indicates the torque reflection rate. The ignition timing adjustment map T6 indicates the retard angle corresponding to the torque reflection rate. As is well known, the torque of the engine 10 can be adjusted by advancing or retarding the ignition timing with respect to MBT.

[0031] As described above, the throttle opening shown in the preparation map T5 of FIG. 6 is set such that a torque higher than the assumed required torque is output. Therefore, before the tumble generator valve V2 is actually switched from the closed position to the open position, it is necessary to control the engine 10 so that the required torque is output. In the present disclosure, this control is executed by adjusting the ignition timing of the ignition plug P. Specifically, the processor 51 calculates, as a torque reflection rate, the ratio of the required torque to the torque at the throttle opening shown in the preparation map T5 of FIG. 6. Subsequently, the processor 51 determines a retard angle corresponding to the required torque by referring to the ignition timing adjustment map T6 of FIG. 7 together with the calculated torque reflection rate. According to such a configuration, the processor 51 can adjust the ignition timing of the ignition plug P so that the engine 10 outputs the required torque before the tumble generator valve V2 is actually switched from the closed position to the open position.

[0032] As can be understood from the above description, in the lean burn operation and the stoichiometric operation, the ignition timing of the ignition plug P is controlled based on the first base map T1 shown in FIG. 2. In contrast, when the tumble generator valve V2 is switched between the closed position and the open position, that is, when the engine 10 is switched between the lean burn operation and the stoichiometric operation, the ignition timing of the ignition plug P is controlled based on the preparation map T5 of FIG. 6 and the ignition timing adjustment map T6 of FIG. 7.

[0033] FIG. 8 shows an adjustment torque map T7 stored in the storage medium 52. In the adjustment torque map T7, the horizontal axis represents the rotational speed of the engine 10, and the vertical axis represents the intake air amount of the engine 10. The adjustment torque map T7 indicates the adjustment torque according to the rotational speed and intake air amount of the engine 10. Each cell includes an adjustment torque corresponding to the rotational speed and intake air amount indicating the cell (not shown). In the present disclosure, the "adjustment torque" means a torque capable of suppressing torque fluctuations due to fluctuations in the intake air amount when the tumble generator valve V2 is switched between the closed position and the open position, and changes according to the rotational speed and intake air amount of the engine 10. The processor 51 determines the corresponding adjustment torque by referring to the adjustment torque map T7 together with the rotational speed and intake air amount. The processor 51 controls the engine 10 based on the adjustment torque when the tumble generator valve V2 is actually switched from the closed position to the open position.

[0034] FIG. 9 shows a torque adjustment rate map T8 stored in the storage medium 52. In the torque adjustment rate map T8, the horizontal axis represents the absolute value of the acceleration of the vehicle 500, and the vertical axis represents the gear ratio of the vehicle 500. The torque adjustment rate map T8 indicates the torque adjustment rate according to the acceleration and gear ratio of the vehicle 500. Each cell includes a torque adjustment rate corresponding to the acceleration and gear ratio indicating the cell (not shown). In the present disclosure, the "torque adjustment rate" means a parameter for adapting the adjustment torque to the actual acceleration situation of the vehicle 500, and changes according to the acceleration and gear ratio of the vehicle 500. For example, the higher the acceleration, the smaller the torque adjustment rate, and the lower the acceleration, the larger the torque adjustment rate. Also, for example, the higher the gear ratio, the smaller the torque adjustment rate, and the lower the gear ratio, the larger the torque adjustment rate. The acceleration is measured by the acceleration sensor Se4. The gear ratio is calculated based on the gear ratios in components such as the transmission and differential. The processor 51 determines the corresponding torque adjustment rate by referring to the torque adjustment rate map T8 together with the acceleration and gear ratio.

[0035] The processor 51 calculates a substantial adjustment torque by multiplying the adjustment torque determined based on FIG. 8 by the torque adjustment rate determined based on FIG. 9. Subsequently, the processor 51 calculates, as a torque reflection rate, the ratio of the substantial adjustment torque to the torque at the throttle opening shown in the preparation map T5 of FIG. 6. Subsequently, the processor 51 determines a retard angle corresponding to the substantial adjustment torque by referring to the ignition timing adjustment map T6 of FIG. 7 together with the calculated torque reflection rate. According to such a configuration, the processor 51 can adjust the ignition timing of the spark plug P so that the engine 10 outputs a substantial adjustment torque when the tumble generator valve V2 is actually switched from the closed position to the open position.

[0036] Even though the engine 10 is operated based on the substantial adjustment torque, when the torque fluctuation of the engine 10, that is, the rotational fluctuation when the tumble generator valve V2 is switched from the closed position to the open position is not within a predetermined range, the adjustment torque map T7 of FIG. 8 is corrected based on FIGS. 10 and 11 below.

[0037] FIG. 10 is a first correction map T9 stored in the storage medium 52. In the first correction map T9, the horizontal axis represents the rotational speed of the engine 10, and the vertical axis represents the rotational fluctuation of the engine 10. The first correction map T9 shows a correction value for the adjustment torque according to the rotational speed and rotational fluctuation of the engine 10. Each cell includes a correction value corresponding to the rotational speed and rotational fluctuation indicating the cell (not shown). For example, when the absolute value of the rotational fluctuation is larger, the absolute value of the correction value is larger, and when the absolute value of the rotational fluctuation is smaller, the absolute value of the correction value is smaller. Also, when the rotational speed is higher, the correction value is larger, and when the rotational speed is lower, the correction value is smaller. The rotational fluctuation is calculated based on the rotational speed measured by the crank angle sensor Se1. For example, the rotational fluctuation can be calculated like the angular velocity difference for each combustion cycle. The processor 51 determines the corresponding correction value by referring to the first correction map T9 together with the rotational speed and rotational fluctuation.

[0038] When the adjustment torque is excessive (i.e., when the acceleration is positive), the rotational fluctuation of the engine 10 takes a negative value. Therefore, as shown in FIG. 10, when the rotational fluctuation is a negative value, the correction value takes a negative value in order to reduce the excessive adjustment torque.

[0039] In contrast, when the adjustment torque is insufficient (i.e., when the acceleration is negative), the rotational fluctuation of the engine 10 takes a positive value. Therefore, as shown in FIG. 10, when the rotational fluctuation is a positive value, the correction value takes a positive value in order to reduce the insufficient adjustment torque.

[0040] FIG. 11 shows a second correction map T10 stored in the storage medium 52. In the second correction map T10, the horizontal axis represents the intake air amount of the engine 10, and the vertical axis represents the rotational fluctuation of the engine 10. The second correction map T10 shows a correction coefficient according to the intake air amount and the rotational fluctuation of the engine 10. Each cell includes a correction coefficient corresponding to the intake air amount and the rotational fluctuation indicating the cell (not shown). In the present disclosure, the "correction coefficient" means a parameter for adapting the correction value to the actual operating condition of the engine 10, and changes according to the intake air amount and the rotational fluctuation of the engine 10. For example, the higher the intake air amount, the larger the correction coefficient, and the lower the intake air amount, the smaller the correction coefficient. Also, for example, the larger the absolute value of the rotational fluctuation, the larger the correction coefficient, and the smaller the absolute value of the rotational fluctuation, the smaller the correction coefficient. The processor 51 determines the corresponding correction coefficient by referring to the second correction map T10 together with the intake air amount and the rotational fluctuation. For example, the correction coefficient is a positive value.

[0041] The processor 51 calculates a substantial correction value by multiplying the correction value determined based on FIG. 10 by the correction coefficient determined based on FIG. 11. Subsequently, the processor 51 corrects the adjustment torque map T7 by subtracting the calculated substantial correction value from the adjustment torque in FIG. 8. For example, only the corresponding adjustment torque among the adjustment torques in the adjustment torque map T7 may be corrected. Alternatively, a plurality of adjustment torques including the corresponding adjustment torque among the adjustment torques in the adjustment torque map T7 may be corrected.

[0042] In the above description regarding FIGS. 2 to 11, the maps T1 to T10 are described as being used when the engine 10 is switched from lean burn operation to stoichiometric operation, that is, when the tumble generator valve V2 is switched from the closed position to the open position. The storage medium 52 may store a similar map (not shown) that is used when the engine 10 is switched from stoichiometric operation to lean burn operation, that is, when the tumble generator valve V2 is switched from the open position to the closed position.

[0043] For example, the storage medium 52 may store a map corresponding to the first determination map T3 in FIG. 4, and this map is used to determine whether the tumble generator valve V2 is likely to be switched from the open position to the closed position. Also, for example, the storage medium 52 may store a map corresponding to the second determination map T4 in FIG. 5, and this map is used to determine whether the tumble generator valve V2 maintains the open position without being switched to the closed position. Also, for example, the storage medium 52 may store maps corresponding to the adjustment torque map T7 in FIG. 8 and the torque adjustment rate map T8 in FIG. 9, and these maps are used to determine the substantial adjustment torque that can suppress torque fluctuations due to fluctuations in the intake air amount when the tumble generator valve V2 is switched from the open position to the closed position. Regarding the remaining maps from FIG. 2 to FIG. 11, they may be used both when the tumble generator valve V2 is switched from the closed position to the open position and when it is switched from the open position to the closed position, or the storage medium 52 may further store maps corresponding to the remaining maps from FIG. 2 to FIG. 11.

[0044] FIG. 12 is a functional block diagram of the ECU 50. When the engine 10 is switched between lean burn operation and stoichiometric operation, that is, when the tumble generator valve V2 is switched between the closed position and the open position, the processor 51 functions as the first determination unit 54, the map switching unit 55, the second determination unit 56, the third determination unit 57, the adjustment torque operation unit 58, the fourth determination unit 59, the fifth determination unit 60, the sixth determination unit 61, the seventh determination unit 62, the eighth determination unit 63, and the correction unit 64 in accordance with the instructions stored in the storage medium 52 while using the above maps.

[0045] In the following description, the processor 51 will be described as functioning as these functional units when the engine 10 is switched from lean burn operation to stoichiometric operation, that is, when the tumble generator valve V2 is switched from the closed position to the open position. However, the processor 51 may function in the same manner also when the engine 10 is switched from lean burn operation to stoichiometric operation, that is, when the tumble generator valve V2 is switched from the closed position to the open position.

[0046] When functioning as the first determination unit 54, the processor 51 determines whether there is a high possibility that the tumble generator valve V2 is switched from the closed position to the open position. Specifically, the processor 51 estimates the torque of the engine 10 by referring to the second base map T2 of FIG. 3 together with the rotational speed and the intake air amount. Further, the processor 51 determines the corresponding first threshold value by referring to the first determination map T3 of FIG. 4 together with the rotational speed and the intake air amount. Subsequently, the processor 51 determines whether the estimated torque of the engine 10 is greater than the first threshold value.

[0047] When functioning as the map switching unit 55, the processor 51 switches the map for controlling the ignition timing of the spark plug P from the first base map T1 of FIG. 2 to the standby map T5 of FIG. 6.

[0048] When functioning as the second determination unit 56, the processor 51 determines whether the tumble generator valve V2 has actually been switched from the closed position to the open position. Specifically, the processor 51 sends a command to the tumble generator valve V2 to send its position. The processor 51 determines whether the tumble generator valve V2 has actually been switched based on the response indicating the open position or the closed position received from the tumble generator valve V2.

[0049] When functioning as the third determination unit 57, the processor 51 determines whether the tumble generator valve V2 maintains the closed position without being switched to the open position. Specifically, the processor 51 estimates the torque of the engine 10 by referring to the second base map T2 in FIG. 3 together with the rotational speed and the intake air amount. Further, the processor 51 determines the corresponding second threshold value by referring to the second determination map T4 in FIG. 5 together with the rotational speed and the intake air amount. Subsequently, the processor 51 determines whether the estimated torque of the engine 10 is smaller than the second threshold value.

[0050] When functioning as the adjustment torque operation unit 58, the processor 51 operates the engine 10 based on the adjustment torque. Specifically, the processor 51 determines the corresponding adjustment torque by referring to the adjustment torque map T7 in FIG. 8 together with the rotational speed and the intake air amount. Further, the processor 51 determines the corresponding torque adjustment rate by referring to the torque adjustment rate map T8 in FIG. 9 together with the acceleration and the gear ratio. Subsequently, the processor 51 calculates the substantial adjustment torque by multiplying the adjustment torque by the torque adjustment rate. Subsequently, the processor 51 determines the corresponding throttle opening by referring to the standby map T5 in FIG. 6 together with the rotational speed and the substantial adjustment torque. Subsequently, the processor 51 calculates, as the torque reflection rate, the ratio of the substantial adjustment torque to the torque at the determined throttle opening. Subsequently, the processor 51 determines the retard angle corresponding to the substantial adjustment torque by referring to the ignition timing adjustment map T6 in FIG. 7 together with the calculated torque reflection rate. Then, the processor 51 controls the throttle valve V1 at the throttle opening determined based on the standby map T5 in FIG. 6, and controls the ignition plug P at the retard angle determined based on the ignition timing adjustment map T6 in FIG. 7, thereby operating the engine 10. Note that the processor 51 may control the fuel injection amount from the injector 17 according to the throttle opening of the throttle valve V1 so as to obtain a desired air-fuel ratio.

[0051] When functioning as the fourth determination unit 59, the processor 51 determines whether the rotational fluctuation is within a predetermined first range. Specifically, the processor 51 calculates the rotational fluctuation when the engine 10 is operated based on the adjustment torque. The processor 51 determines whether this rotational fluctuation is within the first range. For example, the first range can be a range of rotational fluctuations such that the occupant does not feel the shock caused by these rotational fluctuations or does not feel uncomfortable due to such a shock. For example, the first range can be obtained in advance by experiments or CAE and is stored in the storage medium 52.

[0052] When functioning as the fifth determination unit 60, the processor 51 determines whether the acceleration fluctuation is within a predetermined second range. For example, the acceleration fluctuation can be calculated like the sensor output value. Specifically, the processor 51 calculates the acceleration fluctuation when the engine 10 is operated based on the adjustment torque. Such an acceleration fluctuation can appear later than the rotational fluctuation. Therefore, the processor 51 may determine whether the acceleration fluctuation that appears several cycles after the rotational fluctuation is within the second range. For example, the delay of the acceleration fluctuation with respect to the rotational fluctuation can be obtained in advance by experiments or CAE and is stored in the storage medium 52. Also, the second range can be a range of acceleration fluctuations such that the occupant does not feel the shock caused by these acceleration fluctuations or does not feel uncomfortable due to such a shock. For example, the second range can be obtained in advance by experiments or CAE and is stored in the storage medium 52.

[0053] When functioning as the sixth determination unit 61, the processor 51 determines whether the average value of the acceleration fluctuations before the tumble generator valve V2 switches to the open position is greater than a predetermined third threshold value. Specifically, the processor 51 reads from the storage medium 52 the acceleration over a predetermined period measured by the acceleration sensor Se4 before the tumble generator valve V2 switches to the open position. Based on these accelerations, the processor 51 calculates the average value of the acceleration fluctuations during this period. The processor 51 determines whether this average value of the acceleration fluctuations is greater than the third threshold value. For example, the third threshold value can be determined in advance by experiment or CAE considering acceleration fluctuations caused by factors such as rough roads and may be stored in the storage medium 52. If the average value of the acceleration fluctuations before the tumble generator valve V2 switches to the open position is greater than the third threshold value, the acceleration fluctuations after the tumble generator valve V2 switches to the open position may also be caused by factors such as rough roads. In this case, the processor 51 does not correct the adjustment torque in FIG. 8.

[0054] When functioning as the seventh determination unit 62, the processor 51 determines whether the acceleration fluctuation when the engine 10 is operated based on the adjustment torque is positive and the rotational fluctuation when the engine 10 is operated based on the adjustment torque is negative. As described above, when the acceleration of the vehicle 500 is positive, the rotational fluctuation takes a negative value. If the acceleration fluctuation is positive and the rotational fluctuation is also positive, this rotational fluctuation can be considered to be caused by factors other than the adjustment torque. In this case, the processor 51 does not correct the adjustment torque in FIG. 8.

[0055] When functioning as the eighth determination unit 63, the processor 51 determines whether the acceleration fluctuation when the engine 10 is operated based on the adjustment torque is negative and whether the rotational fluctuation when the engine 10 is operated based on the adjustment torque is positive. As described above, when the acceleration of the vehicle 500 is negative, the rotational fluctuation takes a positive value. When the acceleration fluctuation is negative and the rotational fluctuation is also negative, this rotational fluctuation may be considered to be caused by factors other than the adjustment torque. In this case, the processor 51 does not correct the adjustment torque in FIG. 8.

[0056] When functioning as the correction unit 64, the processor 51 adjusts the adjustment torque in FIG. 8 based on the rotational fluctuation. Specifically, the processor 51 determines the corresponding correction value by referring to the first correction map T9 in FIG. 10 together with the rotational speed and the rotational fluctuation. Also, the processor 51 determines the corresponding correction coefficient by referring to the second correction map T10 in FIG. 11 together with the intake air amount and the rotational fluctuation. Subsequently, the processor 51 calculates the substantial correction value by multiplying the correction value by the correction coefficient. Subsequently, the processor 51 corrects the adjustment torque map T7 by subtracting the substantial correction value from the corresponding adjustment torque in FIG. 8. A plurality of adjustment torques including the corresponding adjustment torque may be corrected.

[0057] Subsequently, the operation of the system 100 will be described.

[0058] FIGS. 13 and 14 are flowcharts showing the processing of the ECU 50.

[0059] The following description will explain the processing of the ECU 50 when the engine 10 is switched from lean burn operation to stoichiometric operation, that is, when the tumble generator valve V2 is switched from the closed position to the open position. However, when the engine 10 is switched from lean burn operation to stoichiometric operation, that is, when the tumble generator valve V2 is switched from the closed position to the open position, the ECU 50 may also execute similar processing.

[0060] For example, the processor 51 may repeat the processes shown in FIGS. 13 and 14 at a predetermined interval (for example, ten to several tens of milliseconds, one hundred to several hundreds of milliseconds, one to several seconds, ten to several tens of seconds, or one to several minutes) while the engine 10 is operating in lean burn. During lean burn operation, the processor 51 controls the ignition timing of the spark plug P based on the first base map T1 in FIG. 2.

[0061] Referring to FIG. 13, the processor 51 determines whether the torque of the engine 10 is greater than a first threshold (step S100). The specific process of the processor 51 in this case is the same as the process executed by the processor 51 as the first determination unit 54 described above.

[0062] If it is determined in step S100 that the torque of the engine 10 is not greater than the first threshold (NO), the processor 51 ends the series of processes. In this case, the engine 10 continues lean burn operation without being switched to stoichiometric operation.

[0063] If it is determined in step S100 that the torque of the engine 10 is greater than the first threshold (YES), the processor 51 switches the map for controlling the ignition timing of the spark plug P from the first base map T1 in FIG. 2 to the standby map T5 in FIG. 6 (step S102). The specific process of the processor 51 in this case is the same as the process executed by the processor 51 as the map switching unit 55 described above.

[0064] After step S102, the processor 51 controls the ignition timing of the spark plug P based on the preparation map T5 in FIG. 6 and the ignition timing adjustment map T6 in FIG. 7. Specifically, the processor 51 determines the corresponding throttle opening by referring to the preparation map T5 together with the rotational speed and the required torque. Further, the processor 51 calculates, as the torque reflection rate, the ratio of the required torque to the torque at this throttle opening. The processor 51 determines the retard angle corresponding to the required torque by referring to the ignition timing adjustment map T6 in FIG. 7 together with the calculated torque reflection rate. The processor 51 controls the throttle valve V1 at the throttle opening determined based on the preparation map T5 and controls the ignition timing of the spark plug P at the retard angle determined based on the ignition timing adjustment map T6, thereby operating the engine 10.

[0065] Subsequently, the processor 51 determines whether or not the tumble generator valve V2 has actually been switched from the closed position to the open position (step S104). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the second determination unit 56 described above.

[0066] In step S104, when it is determined that the tumble generator valve V2 has not yet been switched from the closed position to the open position (NO), the processor 51 determines whether or not the torque of the engine 10 is less than the second threshold value (step S106). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the third determination unit 57 described above.

[0067] In step S106, when it is determined that the torque of the engine 10 is less than the second threshold value (YES), the processor 51 ends a series of processing. In this case, the engine 10 continues the lean burn operation without being switched to the stoichiometric operation. In contrast, when it is determined that the torque of the engine 10 is not less than the second threshold value (NO), the processor 51 repeats step S104.

[0068] In step S104, when it is determined that the tumble generator valve V2 has actually been switched from the closed position to the open position (YES), the processor 51 operates the engine 10 based on the adjustment torque (step S108). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the above-described adjustment torque operation unit 58. In this case, the engine 10 is switched from the lean burn operation to the stoichiometric operation.

[0069] Subsequently, the processor 51 determines whether the rotational fluctuation is within the first range (step S110). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the above-described fourth determination unit 59.

[0070] In step S110, when it is determined that the rotational fluctuation is within the first range (YES), the processor 51 ends the series of processes. The engine 10 continues the stoichiometric operation. Also, when the engine 10 is switched from the lean burn operation to the stoichiometric operation next time, the uncorrected adjustment torque map T7 is used.

[0071] In step S110, when it is determined that the rotational fluctuation is not within the first range (NO), the processor 51 determines whether the acceleration fluctuation is within the second range (step S112). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the above-described fifth determination unit 60.

[0072] In step S112, when it is determined that the acceleration fluctuation is within the second range (YES), the processor 51 ends the series of processes. The engine 10 continues the stoichiometric operation. Also, when the engine 10 is switched from the lean burn operation to the stoichiometric operation next time, the uncorrected adjustment torque map T7 is used.

[0073] In step S112, when it is determined that the acceleration fluctuation is within the second range (YES), referring to FIG. 14, the processor 51 determines whether the average value of the acceleration fluctuation before the tumble generator valve V2 is switched to the open position is greater than the third threshold value (step S200). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the above-described sixth determination unit 61.

[0074] In step S200, when it is determined that the average value of the acceleration fluctuation before the tumble generator valve V2 is switched to the open position is greater than the third threshold value (YES), the processor 51 ends a series of processes. The engine 10 continues the stoichiometric operation. When the engine 10 is switched from the lean burn operation to the stoichiometric operation next time, the uncorrected adjustment torque map T7 is used.

[0075] In step S200, when it is determined that the average value of the acceleration fluctuation before the tumble generator valve V2 is switched to the open position is not greater than the third threshold value (NO), the processor 51 determines whether the acceleration fluctuation is positive and the rotational fluctuation is negative (step S202). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the above-described seventh determination unit 62.

[0076] In step S202, when it is determined that the acceleration fluctuation is positive and the rotational fluctuation is negative (YES), the processor 51 corrects the adjustment torque in FIG. 8 (step S204). The specific processing of the processor 51 in this case is the same as the processing executed by the processor 51 as the above-described correction unit 64. The processor 51 ends a series of processes. The engine 10 continues the stoichiometric operation. When the engine 10 is switched from the lean burn operation to the stoichiometric operation next time, the corrected adjustment torque map T7 is used.

[0077] In step S202, when it is not determined that the acceleration fluctuation is positive and the rotational fluctuation is negative (NO), the processor 51 determines whether the acceleration fluctuation is negative and the rotational fluctuation is positive (step S206). The specific process of the processor 51 in this case is the same as the process executed by the processor 51 as the above-described eighth determination unit 63.

[0078] In step S206, when it is determined that the acceleration fluctuation is negative and the rotational fluctuation is positive (YES), the processor 51 proceeds to step S204 and ends a series of processes. The engine 10 continues the stoichiometric operation. When the engine 10 is switched from the lean burn operation to the stoichiometric operation next time, the corrected adjustment torque map T7 is used.

[0079] In step S206, when it is not determined that the acceleration fluctuation is negative and the rotational fluctuation is positive (NO), this means that the acceleration fluctuation is positive and the rotational fluctuation is also positive, or the acceleration fluctuation is negative and the rotational fluctuation is also negative. Therefore, in this case, the processor 51 ends a series of processes. The engine 10 continues the stoichiometric operation. When the engine 10 is switched from the lean burn operation to the stoichiometric operation next time, the uncorrected adjustment torque map T7 is used.

[0080] The system 100 as described above includes an engine 10 including a tumble generator valve V2 that generates a swirling flow in a combustion chamber 13, a crank angle sensor Se1 that measures the rotational speed of the engine 10, an acceleration sensor Se4 that measures the acceleration of a vehicle 500 in which the engine 10 is provided, and an ECU 50 that controls the engine. The tumble generator valve V2 is operable between an open position and a closed position that generates a swirling flow. The ECU 50 includes one or more processors 51 and one or more storage media 52 that store instructions executed by the one or more processors 51. The one or more storage media 52 store an adjustment torque for controlling the engine 10 when the tumble generator valve V2 is switched between the open position and the closed position. The one or more processors 51, in accordance with the instructions, determine whether the tumble generator valve V2 has been switched between the open position and the closed position, operate the engine 10 based on the adjustment torque when it is determined that the tumble generator valve V2 has been switched between the open position and the closed position, determine whether rotational fluctuations obtained based on the rotational speed measured by the crank angle sensor Se1 are within a first range after the engine 10 has been operated based on the adjustment torque, determine whether acceleration fluctuations obtained based on the acceleration measured by the acceleration sensor Se4 are within a predetermined second range after the engine 10 has been operated based on the adjustment torque, and correct the adjustment torque based on the rotational fluctuations when the rotational fluctuations are not within the first range and the acceleration fluctuations are not within the second range. According to such a configuration, when the tumble generator valve V2 is switched between the open position and the closed position, the engine 10 is operated based on the adjustment torque. Also, when the rotational fluctuations are large after the engine 10 has actually been operated based on the adjustment torque, the adjustment torque is corrected to reduce the rotational fluctuations. Therefore, when the tumble generator valve V2 is switched between the open position and the closed position next time, the engine 10 is operated based on the corrected adjustment torque.Therefore, when the tumble generator valve V2 is switched between the open position and the closed position next time, engine rotational fluctuations, i.e., torque fluctuations, can be suppressed.

[0081] Also, in the system 100, the one or more storage media 52 store the adjustment torque according to the engine speed and the intake air amount of the engine 10. Operating the engine 10 based on the adjustment torque includes determining the adjustment torque according to the engine speed and the intake air amount of the engine 10, determining the torque adjustment rate based on the acceleration, and operating the engine based on the actual adjustment torque obtained by multiplying the adjustment torque by the torque adjustment rate. According to such a configuration, the adjustment torque is adapted to the actual acceleration situation of the vehicle 500 by the torque adjustment rate. For this reason, the discomfort of the occupant is reduced.

[0082] Also, in the system 100, correcting the adjustment torque includes determining a correction value according to the rotational fluctuations and the engine speed of the engine 10, determining a correction coefficient according to the rotational fluctuations and the intake air amount of the engine 10, and adding the actual correction value obtained by multiplying the correction value by the correction coefficient to the adjustment torque. According to such a configuration, the correction value is adapted to the actual operating situation of the engine 10 by the correction coefficient. For this reason, the discomfort of the occupant is reduced.

[0083] As described above, the embodiments have been described with reference to the accompanying drawings, but the present invention is not limited to such embodiments. It is obvious that those skilled in the art can conceive various modification examples or correction examples within the scope described in the claims, and it is naturally understood that they also belong to the technical scope of the present invention. Also, the steps of the ECU 50 in the above embodiments do not have to be performed in the above order, and can be performed in a different order as long as there is no technical contradiction.

[0084] For example, in the above embodiment, the ECU 50 stores various relationships as maps T1 to T10. However, in other embodiments, for example, the ECU 50 may store at least one of these relationships as a function. Also, in the above embodiment, the system 100 is applied to the engine 10 operating in lean burn. However, in other embodiments, the system 100 may be applied to an engine 10 that does not operate in lean burn.

Explanation of Signs

[0085] 10 Engine 13 Combustion Chamber 50 ECU (Storage Device) 51 Processor 52 Storage Medium 100 Engine Control System 500 Vehicle Se1 Crank Angle Sensor Se4 Acceleration Sensor V2 Tumbler Generator Valve (Valve for generating swirl flow)

Claims

1. An engine including a valve that generates a swirling flow in a combustion chamber, a crank angle sensor that measures the rotational speed of the engine, an acceleration sensor that measures the acceleration of a vehicle on which the engine is provided, a control device that controls the engine, comprising: the valve is operable between an open position and a closed position that generates the swirling flow; the control device includes one or more processors and one or more storage media that store instructions executed by the one or more processors; the one or more storage media store an adjustment torque for controlling the engine when the valve is switched between the open position and the closed position; the one or more processors, in accordance with the instructions, determine whether the valve has been switched between the open position and the closed position; when it is determined that the valve has been switched between the open position and the closed position, operate the engine based on the adjustment torque; after the engine is operated based on the adjustment torque, determine whether rotational fluctuations obtained based on the rotational speed measured by the crank angle sensor are within a predetermined first range; after the engine is operated based on the adjustment torque, determine whether acceleration fluctuations obtained based on the acceleration measured by the acceleration sensor are within a predetermined second range; when the rotational fluctuations are not within the first range and the acceleration fluctuations are not within the second range, correct the adjustment torque based on the rotational fluctuations; An engine control system configured to perform the above.

2. the one or more storage media store an adjustment torque according to the rotational speed and load of the engine; operating the engine based on the adjustment torque includes: determining the adjustment torque according to the rotational speed and load of the engine; determining a torque adjustment rate based on the acceleration; operating the engine based on a substantial adjustment torque obtained by multiplying the adjustment torque by the torque adjustment rate; The engine control system according to Claim 1, comprising the above.

3. Correcting the adjustment torque includes: determining a correction value according to the rotational fluctuations and rotational speed of the engine; determining a correction coefficient according to the rotational fluctuations and load of the engine; Adding a substantial correction value obtained by multiplying the correction value by the correction coefficient to the adjustment torque; The engine control system according to claim 1 or 2, comprising:

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