Engine Management System

Abstract

To optimize a fuel injection amount at start of an engine.SOLUTION: An engine control system 100 includes an engine 10 and a control device 50. A processor 51 of the control device 50 is configured to execute: learning a friction state in the engine 10 on the basis of at least one of speed or torque of the engine 10 at start by using a starter ST before combustion of the engine 10 in accordance with a command stored in a storage medium 52; determining a first correction value on the basis of the friction state; learning a fuel property on the basis of the speed of the engine 10 after start of combustion at start of the engine 10; determining a second correction value on the basis of the fuel property; and calculating a fuel injection amount at start of the engine 10 on the basis of the first correction value and the second correction value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In this technical field, techniques have been proposed for adjusting the amount of fuel injected depending on the fuel properties in order to reduce particulate matter (PM) in exhaust gases when an engine is started (see, for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-27010 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-25060 [Patent Document 3] Japanese Patent Application Publication No. 8-210162 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-203332 Summary of the Invention [Problem to be solved by the invention]

[0004] Combustion during engine start-up can be affected not only by fuel properties but also by other factors such as component tolerances or engine oil properties, etc. Therefore, there is a need in the art for a technique that can further optimize the amount of fuel injected during engine start-up.

[0005] An object of the present invention is to provide an engine control system that can optimize the amount of fuel injected when starting the engine. [Means for solving the problem]

[0006] An engine control system according to one aspect of the present invention includes: The engine and a control device for controlling the engine; Equipped with the control device includes one or more processors and one or more storage media that store instructions to be executed by the one or more processors; The one or more processors, in accordance with the instructions: learning a friction state within the engine based on at least one of the engine speed and torque when the engine is started by a starter before combustion; determining a first correction value based on the friction condition; learning fuel properties based on the engine speed after combustion starts when the engine is started; determining a second correction value based on the fuel properties; calculating a fuel injection amount at the time of starting the engine based on the first correction value and the second correction value; configured to run 、 the one or more storage media store a table including a plurality of lattice points, each of which stores the friction state corresponding to a specific coolant temperature and a specific engine oil temperature; The one or more processors, in accordance with the instructions: learning the friction state when both the coolant temperature and the engine oil temperature are within a predetermined range from any one of the grid points; When at least one of the coolant temperature and the engine oil temperature is not within a predetermined range from any grid point, the learning of the friction state is stopped; The method is further configured to: An engine control system according to another aspect of the present invention includes: The engine and a control device for controlling the engine; Equipped with the control device includes one or more processors and one or more storage media that store instructions to be executed by the one or more processors; The one or more processors, in accordance with the instructions: learning a friction state within the engine based on at least one of the engine speed and torque when the engine is started by a starter before combustion; determining a first correction value based on the friction condition; learning fuel properties based on the engine speed after combustion starts when the engine is started; determining a second correction value based on the fuel properties; calculating a fuel injection amount at the time of starting the engine based on the first correction value and the second correction value; configured to run The one or more processors, in accordance with the instructions: determining whether a difference between the calculated injection amount and the injection amount stored in the one or more storage media at the time of the previous start is within a predetermined range; If the difference is not within the predetermined range, recalculating the injection amount so that the difference is within the predetermined range; The method is further configured to: [Effects of the Invention]

[0007] According to the present invention, the amount of fuel injected at engine start can be adjusted. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an engine control system according to an embodiment. [Figure 2] FIG. 2 is a functional block diagram of the ECU. [Figure 3] Figure 3 is a table for friction learning. [Figure 4] FIG. 4 is a graph for determining fuel properties. [Figure 5] FIG. 5 is a flowchart showing friction learning. [Figure 6] FIG. 6 is a flowchart for calculating the amount of fuel injection. [Figure 7] FIG. 7 is a flowchart showing fuel property learning. DETAILED DESCRIPTION OF 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 the embodiments are merely examples for ease of understanding and do not limit the present invention unless otherwise specified. In the specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation. 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 one embodiment of the present invention. In this disclosure, the engine control system 100 may also be simply referred to as a "system." The system 100 is applied to a vehicle 500, such as a hybrid electric vehicle (HEV), a gasoline-powered automobile, or a diesel-powered automobile. In this embodiment, the vehicle 500 is a gasoline-powered automobile. The system 100 includes an engine 10.

[0011] The engine 10 includes a cylinder 11 and a piston 12. The piston 12 reciprocates within the cylinder 11. The cylinder 11 and the piston 12 define a combustion chamber 13. The piston 12 is connected to a crankshaft 18 by a connecting rod 14.

[0012] In the engine 10 described above, a mixture of air and fuel (gasoline) is combusted in the combustion chamber 13, causing the piston 12 to reciprocate 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 rotation speed of the crankshaft 18, i.e., the rotation speed of the engine 10, is measured by a crank angle sensor Se1. The crank angle sensor Se1 is communicatively connected to an ECU 50 (described later) and transmits measurement data to the ECU 50. Note that for better understanding, only one pair of cylinders 11 and pistons 12 is shown in FIG. 1 , but the engine 10 may include multiple pairs of cylinders 11 and pistons 12.

[0013] The engine 10 includes a starter motor (starter) ST. When the engine 10 is started, the starter motor ST rotates the crankshaft 18 before the air-fuel mixture is combusted. For example, the starter motor ST includes a DC series-wound motor. For example, the starter motor ST is driven at a constant voltage. The starter motor ST is communicatively connected to the ECU 50 and controlled by the ECU 50. For example, in another embodiment in which the vehicle 500 is an HEV, the engine 10 may not include a starter motor, and a motor that is a driving power source may function as a starter.

[0014] The engine 10 includes an intake port 15 and an exhaust port 16. The intake port 15 is connected to an intake pipe 2 via an intake manifold (not shown), and the exhaust port 16 is connected to an exhaust pipe 3 via an exhaust manifold (not shown). 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, for example, by a camshaft (not shown). The camshaft is rotated by a crankshaft 18 via, for example, a rotating belt or the like.

[0015] The engine 10 includes a fuel injector 17. The injector 17 is provided in the combustion chamber 13 and injects fuel into the combustion chamber 13 (so-called direct injection). In another embodiment, the engine 10 may be a premixed engine. The injector 17 is communicatively connected to the ECU 50. The ECU 50 controls the amount of fuel injected from the injector 17.

[0016] The engine 10 includes a spark plug P. The spark plug P is provided in a combustion chamber 13 and ignites a mixture of air and fuel in the combustion chamber 13. The spark plug P is connected to the ECU 50 so as to be able to communicate with the ECU 50. The ECU 50 controls the operation of the spark plug P.

[0017] The system 100 includes a circulation path WP for circulating coolant to the engine 10. The system 100 also includes a temperature sensor Se2 at an arbitrary position on the circulation path WP. The temperature sensor Se2 measures the temperature of the coolant. The temperature sensor Se2 is communicably connected to the ECU 50 and transmits measurement data to the ECU 50.

[0018] The system 100 includes a circulation path OP for engine oil to the engine 10. The system 100 also includes a temperature sensor Se3 at an arbitrary position on the circulation path OP. The temperature sensor Se3 measures the temperature of the engine oil. The temperature sensor Se3 is communicably connected to the ECU 50 and transmits measurement data to the ECU 50.

[0019] The system 100 includes an ECU (control device) 50. For example, the ECU 50 includes one or more processors 51 such as a CPU, one or more storage media 52 such as a ROM and a RAM, and one or more connectors 53. The ECU 50 may further include other components. The components of the ECU 50 are communicatively connected to one another via a bus. The storage medium 52 stores one or more programs to be executed by the processor 51. The programs include instructions for the processor 51. The operation of the ECU 50 described in the present disclosure is realized by the processor 51 executing the instructions stored in the storage medium 52. The ECU 50 is communicatively connected to the components of the system 100 via the connector 53.

[0020] In the system 100 described above, the ECU 50 determines the amount of fuel injected from the injector 17 so as to obtain a target rotation speed at the time of starting. However, the actual rotation speed of the engine 10 may vary depending on factors such as friction within the engine 10 and fuel properties.

[0021] For example, when a constant amount of fuel is injected, if the friction within the engine 10 is high, the actual rotation speed will be low, and if the friction is low, the actual rotation speed will be high.

[0022] In addition, regarding fuel properties, light fuel is easy to burn and heavy fuel is difficult to burn. Therefore, when a certain amount of fuel is injected, the actual rotation speed will be high if light fuel is used and low if heavy fuel is used.

[0023] The system 100 is configured to learn the friction and fuel properties within the engine 10 as described above, and correct the amount of fuel injected from the injector 17 at start-up based on these.

[0024] 2 is a functional block diagram of the ECU 50. The processor 51 functions as an oil change determination unit 54, a fuel supply determination unit 55, a friction learning unit 56, a fuel property learning unit 57, and an injection amount determination unit 58 in accordance with instructions stored in the storage medium 52.

[0025] When functioning as the oil change determination unit 54, the processor 51 is configured to determine whether the engine oil has been changed. Friction within the engine 10 varies depending on the properties of the engine oil. For example, when new engine oil is used, the engine oil has a high viscosity. Therefore, the friction within the engine 10 is high. In contrast, if the engine oil has already been used for a long time, the engine oil may have a low viscosity. In this case, the friction within the engine 10 is low. Therefore, the processor 51 determines whether the engine oil has been changed in order to relearn the friction every time the engine oil is changed.

[0026] For example, the ECU 50 may be configured to receive an input from an operator indicating that the engine oil has been changed. For example, the system 100 may include a mechanical button or a button on a touch panel for receiving such an input. Upon receiving the input, the ECU 50 may turn on a flag indicating that the engine oil has been changed. In other embodiments, the ECU 50 may determine whether the engine oil has been changed using other methods.

[0027] When functioning as the refueling determination unit 55, the processor 51 is configured to determine whether fuel has been refueled. As described above, light fuel is easy to combust and heavy fuel is difficult to combust, so when light fuel is used, the rotation speed increases, and when heavy fuel is used, the rotation speed decreases. For this reason, the processor 51 determines whether fuel has been refueled in order to learn the fuel properties every time fuel is refueled.

[0028] For example, the system 100 may include a sensor for measuring the amount of fuel. When the amount of fuel increases, the ECU 50 may determine that fuel has been refueled and turn on a refueling flag. The ECU 50 may also be configured to receive an input from an operator indicating that fuel has been refueled. For example, the system 100 may include a mechanical button or a button on a touch panel for receiving such an input. Upon receiving the input, the ECU 50 may turn on a refueling flag. In other embodiments, the ECU 50 may determine whether fuel has been refueled using other methods.

[0029] When functioning as the friction learning unit 56, the processor 51 learns the friction conditions within the engine 10 based on at least one of the rotation speed (speed) or torque of the engine 10 when the engine 10 is started by the starter motor ST before combustion of the engine 10 (friction learning).

[0030] Specifically, in this embodiment, the starter motor ST is driven at a constant voltage as described above. In friction learning in this embodiment, the ECU 50 measures the engine 10 rotation speed at a predetermined crank angle in response to a constant input from the starter motor ST using the crank angle sensor Se1. Because the input from the starter motor ST is constant, when the friction within the engine 10 is higher, the engine 10 rotation speed is lower. In contrast, when the friction within the engine 10 is lower, the engine 10 rotation speed is higher. Therefore, by measuring the engine 10 rotation speed, the friction condition within the engine 10 can be estimated. Furthermore, in friction learning, the ECU 50 measures the engine 10 rotation speed before fuel combustion. Therefore, the measured rotation speed does not include the influence of fuel properties.

[0031] Thus, in this embodiment, processor 51 learns the rotation speed of engine 10 as an indicator of the state of friction within engine 10. In other embodiments, processor 51 may learn the torque applied to the starter as an indicator of the state of friction within engine 10. For example, in an embodiment in which vehicle 500 is an HEV, as described above, the motor that is the driving power source may also function as the starter, and torque can be measured by such a motor. In the present disclosure, the value learned in friction learning may also be referred to as a "friction learning value."

[0032] 3 shows a table T1 for friction learning. The storage medium 52 stores the table T1 for storing friction learning values. The friction within the engine 10 can change depending on the temperatures of the coolant and engine oil supplied to the engine 10. For this reason, the table T1 includes a plurality of lattice points g. Each lattice point g stores a friction learning value corresponding to a specific coolant temperature and a specific engine oil temperature.

[0033] For example, table T1 includes a plurality of lattice points g at predetermined coolant temperature intervals, for example, at 10° C. intervals. Table T1 also includes a plurality of lattice points g at predetermined engine oil temperature intervals, for example, at 10° C. intervals. Each lattice point g stores a friction learning value.

[0034] The processor 51 determines whether the coolant temperature measured by the temperature sensor Se2 is within a predetermined range, for example, within ±several degrees, from any grid point g. The processor 51 also determines whether the engine oil temperature measured by the temperature sensor Se3 is within a predetermined range, for example, within ±several degrees, from any grid point g.

[0035] When both the coolant temperature and the engine oil temperature are within a predetermined range from any grid point g, processor 51 starts friction learning. Specifically, processor 51 stores the rotation speed measured by crank angle sensor Se1 at that grid point g.

[0036] In contrast, if at least one of the coolant temperature and the engine oil temperature is not within a predetermined range from any grid point g, the processor 51 stops friction learning. If the coolant temperature or the engine oil temperature is far from the grid point g, the stored friction learning value may differ significantly from the actual friction condition at that grid point. Therefore, by stopping friction learning when the coolant temperature or the engine oil temperature is far from the grid point g, errors in the friction learning value can be suppressed.

[0037] Furthermore, when functioning as the friction learning unit 56, the processor 51 determines a first correction value C1 for calculating the injection amount V at the start of the engine 10, based on the friction learning value stored in the table T1. For example, the storage medium 52 may store a table or a formula (not shown) that indicates the relationship between the friction learning value and the first correction value C1.

[0038] For example, if both the coolant temperature and the engine oil temperature are within a predetermined range from any lattice point g, the processor 51 may read the first correction value C1 corresponding to the friction learning value stored at that lattice point g from a table in the storage medium 52.

[0039] In contrast, if at least one of the coolant temperature or the engine oil temperature is not within a predetermined range from any grid point g, the processor 51 may read the first correction value C1 currently maintained in the storage medium 52.

[0040] For example, the first correction value C1 may be a ratio of the amount of fuel injected at startup to a reference value V0. For example, the reference value V0 is stored in the storage medium 52. Alternatively, the first correction value C1 may be a difference from the reference value V0. In this case, the first correction value C1 may be a positive value or a negative value.

[0041] Referring to FIG. 2, when functioning as fuel property learning unit 57, processor 51 learns the fuel properties based on the rotation speed of engine 10 after combustion starts when engine 10 is started (fuel property learning).

[0042] Figure 4 is a graph for determining fuel properties. Referring to the upper graph in Figure 4, the horizontal axis represents time and the vertical axis represents engine speed. The solid line represents the engine speed measured by the crank angle sensor Se1, the dashed line represents the central target value, the one-dot chain line represents the upper target value, and the two-dot chain line represents the lower target value.

[0043] The storage medium 52 stores a central target value, an upper target value, and a lower target value for the engine 10 rotational speed in order to determine the fuel properties. The central target value is a target rotational speed of the engine 10 at start-up with respect to time. For example, the upper target value may be a value obtained by multiplying the central target value by a predetermined rate higher than 1, or a value obtained by offsetting the central target value upward. For example, the lower target value may be a value obtained by multiplying the central target value by a predetermined rate lower than 1, or a value obtained by offsetting the central target value downward.

[0044] In this embodiment, when starting the engine 10, the processor 51 learns the fuel properties based on the engine 10 rotation speed for a predetermined period after the start of combustion. For example, the "predetermined period" may be the period until the engine 10 achieves complete combustion. For example, the meaning of "complete combustion" may follow the definition of each automobile manufacturer. For example, "complete combustion" may mean reaching a predetermined rotation speed.

[0045] Referring to the lower graph of FIG. 4 , the horizontal axis represents time, and the vertical axis represents the difference in rotation speed and the counter count. The solid line represents the absolute value of the difference between the measurement value shown in the upper graph and the upper target value, or the absolute value of the difference between the measurement value and the lower target value. These "absolute values ​​of the difference" may also be simply referred to as "differences" in this disclosure. If the measurement value is higher than the upper target value at a certain point in time during a specified period, the difference between the measurement value and the upper target value for that point in time is calculated. Also, if the measurement value is lower than the lower target value at a certain point in time during a specified period, the difference between the measurement value and the lower target value for that point in time is calculated. If the measurement value is equal to or lower than the upper target value but equal to or higher than the lower target value, the difference for that point in time may not be calculated. In the example of FIG. 4 , as shown in the upper graph, the measurement value is higher than the upper target value at some points in time, so the lower graph shows the difference between the measurement value and the upper target value. Also, in the example of FIG. 4, as shown in the upper graph, the measured value is never lower than the lower target value, so the lower graph does not show the difference between the measured value and the lower target value.

[0046] In the lower graph of FIG. 4 , the dashed line indicates the upper limit counter, and the dashed line indicates the lower limit counter. The upper limit counter is the cumulative value of the number of times at a certain point in time that the measured value is higher than the upper limit target value. The lower limit counter is the cumulative value of the number of times at a certain point in time that the measured value is lower than the lower limit target value. For example, if the upper limit counter is greater than a certain threshold value after a predetermined period of time after the start of combustion, for example, after complete combustion, the processor 51 determines that the fuel is light fuel. Also, for example, if the lower limit counter is greater than a certain threshold value after a predetermined period of time after the start of combustion, for example, after complete combustion, the processor 51 determines that the fuel is light fuel. In all other cases, the processor 51 determines that the fuel is core fuel.

[0047] Furthermore, when functioning as the fuel property learning unit 57, the processor 51 determines a second correction value C2 for calculating the injection amount V at the start of the engine 10 based on the learned fuel properties. For example, the second correction value C2 may be a ratio to the above-mentioned reference value V0. For example, if the fuel is a light fuel, the second correction value C2 may be a value lower than 1. For example, if the fuel is a heavy fuel, the second correction value C2 may be a value higher than 1. For example, if the fuel is a center fuel, the second correction value C2 may be 1. Alternatively, the second correction value C2 may be a difference from the reference value V0. In this case, the second correction value C2 may be a positive or negative value.

[0048] As described above, the learning of the fuel properties is performed after the fuel is actually injected and combustion starts, so the determined second correction value C2 cannot be used for the current engine start, but is used for the next engine start.

[0049] When functioning as injection amount determination unit 58, processor 51 calculates the fuel injection amount V at the start of engine 10 based on a first correction value C1 determined based on friction learning, a second correction value C2 determined based on fuel property learning, and a reference value V0. For example, if the first correction value C1 and the second correction value C2 are ratios to the reference value V0, processor 51 may calculate the injection amount V as V = V0 × C1 × C2. Alternatively, if the first correction value C1 and the second correction value C2 are differences from the reference value V0, processor 51 may calculate the injection amount V as V = V0 + C1 + C2.

[0050] Next, the operation of the system 100 will be described.

[0051] Fig. 5 is a flowchart showing friction learning. For example, the operation shown in Fig. 5 may be started when the start button of the vehicle 500 is pressed. For example, the operation shown in Fig. 5 may be performed only once when the engine 10 is started.

[0052] The processor 51 determines whether the engine 10 is being started for the first time after the engine oil has been changed (step S100). For example, the processor 51 determines whether the engine oil change flag is on.

[0053] In step S100, if engine 10 is started for the first time after engine oil change (YES), processor 51 resets first correction value C1 in storage medium 52 to an initial value (step S102). For example, the initial value may be 1. Then, processor 51 proceeds to step S104.

[0054] In step S100, if the engine 10 is not started for the first time after the engine oil has been changed (NO), the first correction value C1 is maintained, and the processor 51 proceeds to step S104.

[0055] Next, processor 51 determines whether the coolant temperature from temperature sensor Se2 and the engine oil temperature from temperature sensor Se3 are within a predetermined range from any grid point g (step S104). For example, referring to Fig. 3, processor 51 determines whether the coolant temperature from temperature sensor Se2 is within ±several degrees from the coolant temperature at any grid point g, and whether the engine oil temperature from temperature sensor Se3 is within ±several degrees from the engine oil temperature at any grid point g.

[0056] 5, in step S104, if at least one of the coolant temperature and the engine oil temperature is not within a predetermined range from any of the grid points g (NO), processor 51 ends friction learning. In this case, processor 51 may use first correction value C1 currently stored in storage medium 52 for calculating injection amount V, which will be described later.

[0057] In step S104, if both the coolant temperature and the engine oil temperature are within a predetermined range from any grid point g (YES), the processor 51 determines whether the engine 10 is being started for the first time at that grid point g after the engine oil has been changed (step S106).

[0058] If the engine 10 is started for the first time at the grid point g after the engine oil change (YES in step S106), the processor 51 resets the friction learning value stored at the grid point g, which is the rotation speed in this embodiment (step S108). For example, the processor 51 sets the rotation speed to zero or deletes the rotation speed.

[0059] Next, the processor 51 measures the friction (step S110). Specifically, the processor 51 receives a measurement value from the crank angle sensor Se1.

[0060] Next, processor 51 updates the friction learning value of the corresponding grid point g to the measurement value received from crank angle sensor Se1 (step S112), and proceeds to step S120.

[0061] If the engine 10 is not started for the first time at the grid point g after the engine oil change (NO in step S106), the processor 51 measures friction (step S114). Specifically, the processor 51 receives a measurement value from the crank angle sensor Se1.

[0062] Next, the processor 51 determines whether the measurement value received from the crank angle sensor Se1 is within a predetermined range of the friction learning value stored in the table T1 (step S116). For example, the predetermined range may be a predetermined percentage plus or minus the stored friction learning value.

[0063] In step S116, if the measured value is within a predetermined range from the friction learning value stored in table T1 (YES), processor 51 maintains the stored friction learning value (step S118) and proceeds to step S120.

[0064] In step S116, if the measured value is not within a predetermined range from the friction learning value stored in table T1 (NO), processor 51 updates the friction learning value of the corresponding lattice point g to the measured value received from crank angle sensor Se1 (step S112), and proceeds to step S120.

[0065] Next, the processor 51 determines the first correction value C1 based on the friction learning value (step S120), and ends the friction learning. For example, the processor 51 may read the first correction value C1 corresponding to the friction learning value stored at the corresponding lattice point g from a table in the storage medium 52. The processor 51 stores the determined first correction value C1 in the storage medium 52.

[0066] Fig. 6 is a flowchart for calculating the fuel injection amount. For example, the operation shown in Fig. 6 may be started when the friction learning is completed at the start of the engine 10. For example, the operation shown in Fig. 6 may be performed only once at the start of the engine 10.

[0067] The processor 51 calculates the injection amount V at the start of the engine 10 based on the first correction value C1 determined based on the friction learning at the current start, the second correction value C2 determined based on the fuel property learning at the previous start, and the reference value V0 (step S200).

[0068] Next, the processor 51 determines whether the difference between the calculated injection amount V and the injection amount stored in the storage medium 52 is within a predetermined range (step S202). For example, the predetermined range is several mm 3 / stroke may be used.

[0069] In step S202, if the difference between the calculated injection amount V and the stored injection amount is within a predetermined range (YES), the processor 51 updates the injection amount stored in the storage medium 52 to the calculated injection amount V (step S204), and the series of operations ends.

[0070] If the difference between the calculated injection amount V and the stored injection amount is not within a predetermined range (NO) in step S202, the processor 51 recalculates the injection amount V so that the difference is within the predetermined range (step S206). For example, the processor 51 may recalculate the injection amount V by adding or subtracting a predetermined range to or from the stored injection amount so that the stored injection amount approaches the calculated injection amount V. This configuration can prevent the injection amount at the current start from differing significantly from the injection amount at the previous start. This can prevent combustion abnormalities, for example, when refueling has been performed between the previous start and the current start, changing the fuel properties. Next, the processor 51 updates the injection amount stored in the storage medium 52 to the calculated injection amount V (step S204), and the series of operations ends.

[0071] The injection amount in the storage device 52 updated in step S204 is used for combustion during the current start-up. That is, this injection amount is used in the fuel property learning, which will be described later.

[0072] Fig. 7 is a flowchart showing fuel property learning. For example, the operation shown in Fig. 7 may be started when combustion starts at the start of the engine 10. For example, the operation shown in Fig. 7 may be performed only once at the start of the engine 10.

[0073] The processor 51 determines whether the engine 10 is started for the first time after refueling (step S300). For example, the processor 51 determines whether the refueling flag is on.

[0074] In step S300, if the engine 10 is not started for the first time after refueling (NO), the processor 51 proceeds to step S304.

[0075] If the engine 10 is started for the first time after refueling in step S300 (YES), the processor 51 resets the second correction value C2 in the storage medium 52 to an initial value (step S302). For example, the initial value may be 1. Then, the processor 51 proceeds to step S304.

[0076] Next, the processor 51 determines whether or not the measurement value from the crank angle sensor Se1 is higher than the upper limit target value at a certain point in time during a predetermined period after the start of combustion (step S304).

[0077] In step S304, if the measured value is higher than the upper limit target value at a certain point in time (YES), the processor 51 determines whether the upper limit counter after a predetermined period of time is greater than the threshold value (step S306).

[0078] If the upper limit counter is greater than the threshold value in step S306 (YES), the processor 51 determines that the fuel is a light fuel (step S312). Subsequently, the processor 51 proceeds to step S318.

[0079] If the upper limit counter is not greater than the threshold value (NO) in step S306, the processor 51 determines that the fuel is the center fuel (step S314). Subsequently, the processor 51 proceeds to step S318.

[0080] In step S304, if the measured value is not higher than the upper limit target value at any point during the specified period (NO), processor 51 determines whether the measured value is lower than the lower limit target value at some point during the specified period after combustion starts (step S308).

[0081] In step S308, if the measured value is lower than the lower limit target value at a certain point in time (YES), the processor 51 determines whether the lower limit counter after a predetermined period of time is greater than the threshold value (step S310).

[0082] If the lower limit counter is greater than the threshold value in step S310 (YES), the processor 51 determines that the fuel is heavy fuel (step S316). Subsequently, the processor 51 proceeds to step S318.

[0083] If the lower limit counter is not greater than the threshold value (NO) in step S310, the processor 51 determines that the fuel is the center fuel (step S314). Subsequently, the processor 51 proceeds to step S318.

[0084] In step S308, if the measured value is not lower than the lower limit target value at any time during the predetermined period (NO), the processor 51 determines that the fuel is the center fuel (step S314). Subsequently, the processor 51 proceeds to step S318.

[0085] Next, the processor 51 determines the second correction value C2 based on the fuel properties (step S318), and ends the fuel property learning. The processor 51 stores the determined second correction value C2 in the storage medium 52. The stored second correction value C2 is used to calculate the injection amount V at the next start.

[0086] The system 100 described above includes an engine 10 and an ECU 50 that controls the engine 10. 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 processor 51 is configured to execute the following operations in accordance with the instructions: learn the friction condition within the engine 10 based on at least one of the engine speed and torque of the engine 10 when the engine 10 is started by the starter ST before combustion; determine a first correction value C1 based on the friction condition; learn the fuel properties based on the engine speed after combustion starts when the engine 10 is started; determine a second correction value C2 based on the fuel properties; and calculate the fuel injection amount V at the start of the engine 10 based on the first correction value and the second correction value. With this configuration, the fuel injection amount at the start of the engine 10 is determined taking into account the friction condition within the engine 10 in addition to the fuel properties. Such friction conditions include factors such as the contact state between parts and the properties of the engine oil. Therefore, according to system 100, the injection amount at engine start is calculated taking into account not only the fuel properties but also other factors. This makes it possible to further optimize the injection amount at engine start.

[0087] In the system 100, the storage medium 52 stores a table T1 including a plurality of grid points g, each of which stores a friction condition corresponding to a specific coolant temperature and a specific engine oil temperature. The processor 51 is further configured, in accordance with instructions, to learn the friction condition when both the coolant temperature and the engine oil temperature are within a predetermined range from any grid point g, and to stop learning the friction condition when at least one of the coolant temperature and the engine oil temperature is not within the predetermined range from any grid point g. If the coolant temperature or the engine oil temperature is far from the grid point g, the stored friction learning value may differ significantly from the actual friction condition at that grid point. Therefore, by stopping the friction learning when the coolant temperature or the engine oil temperature is far from the grid point g, errors in the friction learning value can be suppressed.

[0088] In the system 100, the processor 51 is further configured to, in accordance with the instructions, determine whether the difference between the calculated injection amount V and the injection amount stored in the storage medium 52 at the time of the previous start is within a predetermined range, and, if the difference is not within the predetermined range, recalculate the injection amount so that the difference is within the predetermined range. This configuration makes it possible to prevent the injection amount at the current start from differing significantly from the injection amount at the previous start.

[0089] Although the embodiments have been described above with reference to the accompanying drawings, the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations naturally fall within the technical scope of the present invention. Furthermore, the steps of the ECU 50 in the above-described embodiments do not have to be performed in the order described above, and may be performed in a different order as long as no technical contradiction occurs. [Explanation of symbols]

[0090] 10 Engine 50 ECU (control unit) 51 processors 52 Storage medium 100 Engine Control System g grid point ST Starter motor (starter) T1 Table

Claims

1. An engine; a control device for controlling the engine; Equipped with the control device includes one or more processors and one or more storage media that store instructions that are executed by the one or more processors; The one or more processors, in accordance with the instructions: learning a friction state within the engine based on at least one of the engine speed and torque when starting the engine by a starter before combustion; determining a first correction value based on the friction condition; learning fuel properties based on the engine speed after combustion starts when the engine is started; determining a second correction value based on the fuel property; calculating a fuel injection amount at the time of starting the engine based on the first correction value and the second correction value; configured to run the one or more storage media store a table including a plurality of lattice points, each of which stores the friction state corresponding to a specific coolant temperature and a specific engine oil temperature; The one or more processors, in accordance with the instructions: learning the friction state when both the coolant temperature and the engine oil temperature are within a predetermined range from any one of the grid points; When at least one of the coolant temperature and the engine oil temperature is not within a predetermined range from any grid point, stopping learning of the friction state; an engine control system further configured to perform the following:

2. An engine; a control device for controlling the engine; Equipped with the control device includes one or more processors and one or more storage media that store instructions that are executed by the one or more processors; The one or more processors, in accordance with the instructions: learning a friction state within the engine based on at least one of the engine speed and torque when starting the engine by a starter before combustion; determining a first correction value based on the friction condition; learning fuel properties based on the engine speed after combustion starts when the engine is started; determining a second correction value based on the fuel property; calculating a fuel injection amount at the time of starting the engine based on the first correction value and the second correction value; configured to run The one or more processors, in accordance with the instructions: determining whether a difference between the calculated injection amount and the injection amount stored in the one or more storage media at the time of the previous start is within a predetermined range; If the difference is not within the predetermined range, recalculating the injection amount so that the difference is within the predetermined range; an engine control system further configured to perform the following:

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