Vehicle control device

Abstract

To prevent seizure of a start clutch, while suppressing an air-fuel ratio of a cylinder from deviating with respect to a theoretical air-fuel ratio.SOLUTION: A control deice 100 controls a throttle valve so that intake air quantities of an internal combustion engine 10 increase and controls a motor generator 200 so that generated electric power increases, when a start clutch 220 is in a slip state and diluted fuel quantities which are quantities of fuel included in lubricant in the internal combustion engine 10 are equal to a determination value or more, more than when the start clutch 220 is in the slip state and the diluted fuel quantities are less than the determination value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a control device for a vehicle.

Background Art

[0002] Patent Document 1 discloses a hybrid vehicle. The hybrid vehicle has an internal combustion engine, a motor generator, a starting clutch, and a transmission mechanism. The motor generator is located between the internal combustion engine and the transmission mechanism on the torque transmission path. The motor generator can transmit the torque from the internal combustion engine to the transmission mechanism. Also, the motor generator can receive the torque from the internal combustion engine and generate electricity by functioning as a generator, or can apply torque to the transmission mechanism by functioning as an electric motor. The starting clutch is located between the motor generator and the transmission mechanism on the torque transmission path. The starting clutch is a so-called wet start clutch. The starting clutch disconnects and connects the transmission of torque from the motor generator to the transmission mechanism according to the running state of the vehicle. When the depression amount of the brake pedal is small, the starting clutch is in a slip state that allows relative rotation between the rotation shaft of the motor generator and the input shaft of the transmission mechanism while transmitting torque.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an internal combustion engine, part of the fuel supplied to the cylinder may enter the crankcase through the gap between the cylinder and the piston without burning. This fuel can mix with the lubricating oil stored at the bottom of the crankcase. When the temperature of the internal combustion engine rises significantly, the fuel mixed with the lubricating oil vaporizes. The vaporized fuel flows into the intake passage through a blow-by gas passage for returning blow-by gas from the crankcase to the intake passage. In this case, the amount of fuel supplied to the cylinder increases by the amount of fuel contained in the blow-by gas. Therefore, the air-fuel ratio of the cylinder can become richer than the stoichiometric air-fuel ratio.

[0005] In a hybrid vehicle such as that of Patent Document 1 having a starting clutch, it is assumed that the internal combustion engine continues to operate and the starting clutch is in a slip state while the vehicle is stopped. Further, under this situation, it is assumed that the air-fuel ratio of the cylinder has become richer than the stoichiometric air-fuel ratio due to the fuel contained in the blow-by gas. In this case, it may be considered to increase the intake air amount in order to maintain the air-fuel ratio of the cylinder at the stoichiometric air-fuel ratio. However, when the intake air amount is increased, the torque of the internal combustion engine increases. At the same time, the rotational speed of the rotating shaft of the motor generator increases. At this time, if the degree of relative rotation between the rotating shaft of the motor generator and the input shaft of the transmission increases, there is a risk of seizure occurring in the starting clutch in the slip state.

[0006] Note that even when the hybrid vehicle is not stopped, the same problems as described above occur when the internal combustion engine is operating while the starting clutch is in a slip state, such as when the vehicle starts.

Means for Solving the Problems

[0007] A vehicle control device for solving the above problems includes: a cylinder which is a space where a mixture of fuel and intake air burns; a crank chamber communicating with the cylinder; a blow-by gas passage for allowing blow-by gas to flow from the crank chamber to an intake passage; an internal combustion engine including a throttle valve for adjusting the amount of intake air; an automatic transmission including an input shaft; a motor generator located between the internal combustion engine and the automatic transmission on a torque transmission path and having a rotating shaft, capable of generating electricity by torque input from the internal combustion engine; a starting clutch located between the motor generator and the automatic transmission on the torque transmission path, wherein a rotating shaft of the motor generator and the input shaft of the automatic transmission are switched between a direct connection state of transmitting torque without relative rotation, a slip state of transmitting torque while relatively rotating, and a disconnection state of not transmitting torque; and controls a vehicle having the above components. Based on an operating state of the internal combustion engine, the vehicle control device executes: a first process of calculating an amount of diluted fuel which is an amount of fuel contained in lubricating oil of the internal combustion engine; a second process of controlling the starting clutch to be in the slip state when a traveling speed of the vehicle is equal to or lower than a predetermined specified vehicle speed; and a third process of controlling the throttle valve so that an amount of intake air increases and controlling the motor generator so that an amount of generated electricity increases when the starting clutch is in the slip state and the amount of diluted fuel is equal to or greater than a predetermined determination value, as compared with a case where the starting clutch is in the slip state and the amount of diluted fuel is less than the determination value.

[0008] When the amount of diluted fuel is large, the amount of fuel returned to the intake passage through the blow-by gas passage can increase. And the air-fuel ratio of the cylinder can become richer than the stoichiometric air-fuel ratio. When the starting clutch is in a slip state under such circumstances, the above control device increases the intake air amount. By this, the air-fuel ratio of the cylinder can be made closer to the stoichiometric air-fuel ratio. On the other hand, the above control device offsets part or all of the increase in the torque of the internal combustion engine accompanying the increase in the intake air amount by increasing the power generation amount of the motor generator. Therefore, even if the intake air amount is increased, the rotational speed of the rotating shaft of the motor generator does not become excessively high. Therefore, the state where the difference in the rotational speeds of the rotating shaft of the motor generator and the input shaft of the automatic transmission is kept within the allowable range can be maintained. Therefore, seizure of the starting clutch can be prevented.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, an embodiment of a control device for a vehicle will be described with reference to the drawings. <Overall Configuration of the Vehicle> As shown in FIG. 1, the vehicle 500 includes an internal combustion engine 10, a drive clutch 210, a motor generator 200, and a starting clutch 220. The vehicle 500 also includes an automatic transmission 240, a hydraulic circuit 270, a differential 250, a plurality of drive wheels 260, an inverter 204, and a battery 206.

[0011] The internal combustion engine 10 is a power source for the vehicle 500. Details of the internal combustion engine 10 will be described later. The internal combustion engine 10 has a crankshaft 14. The motor generator 200 is a power source for the vehicle 500. The motor generator 200 has both functions of an electric motor and a generator. The motor generator 200 has a rotating shaft 200A, a rotor 200B, and a stator 200C. The rotating shaft 200A rotates integrally with the rotor 200B. The rotor 200B is rotatable with respect to the stator 200C. The motor generator 200 is electrically connected to the battery 206 via an inverter 204. The battery 206 exchanges electric power with the motor generator 200. The inverter 204 performs DC-AC conversion.

[0012] The drive clutch 210 is located between the internal combustion engine 10 and the motor generator 200. The drive clutch 210 disconnects and connects the crankshaft 14 and the rotating shaft 200A of the motor generator 200. When the drive clutch 210 receives hydraulic pressure from the hydraulic circuit 270, it directly connects the crankshaft 14 and the rotating shaft 200A of the motor generator 200. Although not shown, the hydraulic circuit 270 includes a plurality of oil passages, a valve for switching the oil passages through which the hydraulic oil flows, a pump for supplying the hydraulic oil to the oil passages, and the like.

[0013] The automatic transmission 240 is a stepped transmission whose gear ratio is switched in multiple stages according to the hydraulic pressure from the hydraulic circuit 270. The automatic transmission 240 has an input shaft 240A and an output shaft 240B. The automatic transmission 240 shifts the rotation input to the input shaft 240A at the selected gear ratio and outputs it from the output shaft 240B. The output shaft 240B is connected to the left and right drive wheels 260 via a differential 250. The differential 250 allows a difference in rotational speed to occur between the left and right drive wheels 260.

[0014] The starting clutch 220 is a wet multi-plate clutch. The starting clutch 220 is positioned between the motor generator 200 and the automatic transmission 240. The starting clutch 220 has a plurality of first plates that rotate integrally with the rotating shaft 200A of the motor generator 200, and a plurality of second plates that rotate integrally with the input shaft 240A of the automatic transmission 240. The first plate and the second plate approach and separate from each other by the hydraulic pressure from the hydraulic circuit 270. At the same time, the starting clutch 220 assumes any one of a direct connection state, a slip state, and a disconnection state. When the hydraulic pressure from the hydraulic circuit 270 is high, the first plate and the second plate come into contact with each other and strongly press against each other. In this case, the starting clutch 220 is in the direct connection state. The direct connection state is a state in which the rotating shaft 200A of the motor generator 200 and the input shaft 240A of the automatic transmission 240 transmit torque without relative rotation. When the hydraulic pressure from the hydraulic circuit 270 is low, the first plate and the second plate are in positions separated from each other. In this case, the starting clutch 220 is in the disconnection state. The disconnection state is a state in which the rotating shaft 200A of the motor generator 200 and the input shaft 240A of the automatic transmission 240 do not transmit torque. When the hydraulic pressure from the hydraulic circuit 270 is medium, being smaller than in the direct connection state and larger than in the disconnection state, the first plate and the second plate contact each other to the extent that they slip. In this case, the starting clutch 220 is in the slip state. The slip state is a state in which the rotating shaft 200A of the motor generator 200 and the input shaft 240A of the automatic transmission 240 rotate relative to each other and transmit torque.

[0015] In the series of power transmission systems described above, the torque of the internal combustion engine 10 reaches the drive wheels 260 via the drive clutch 210, the motor generator 200, the starting clutch 220, and the automatic transmission 240. That is, the drive clutch 210, the motor generator 200, the starting clutch 220, and the automatic transmission 240 are positioned on the torque transmission path from the internal combustion engine 10 to the drive wheels 260.

[0016] Vehicle 500 has a shift device 290 for switching the shift range Q of the automatic transmission 240. When "D range" is selected by the shift device 290, the automatic transmission 240 forms a gear stage for forward travel. When "R range" is selected by the shift device 290, the automatic transmission 240 forms a gear stage for reverse travel. When "N range" or "P range" is selected by the shift device 290, the automatic transmission 240 cuts off the power transmission between the input shaft 240A and the output shaft 240B.

[0017] Vehicle 500 has a vehicle speed sensor 56, an accelerator sensor 57, a brake sensor 58, a shift sensor 59, and a power switch 60. The vehicle speed sensor 56 detects the traveling speed of vehicle 500 as the vehicle speed SP. The accelerator sensor 57 detects the depression amount of the accelerator pedal in vehicle 500 as the accelerator operation amount ACC. The brake sensor 58 detects the depression amount of the brake pedal in vehicle 500 as the brake operation amount BK. The shift sensor 59 detects the shift range Q selected by the shift device 290. The power switch 60 is a switch for starting the system of vehicle 500. Each of the above sensors repeatedly outputs a signal according to the information it detects to the control device 100 described later. Also, the power switch 60 outputs a signal U according to the driver's operation to the control device 100 described later.

[0018] <Schematic Configuration of Internal Combustion Engine> As shown in FIG. 2, the internal combustion engine 10 has a cylinder block 25, a crankcase 26, and an oil pan 27. The internal combustion engine 10 also has a plurality of cylinders 11, a plurality of pistons 12, a plurality of connecting rods 13, the crankshaft 14, and a crank chamber 28. The number of cylinders 11 is four. In FIG. 2, only one of the plurality of cylinders 11 is shown. The same applies to the pistons 12 and the connecting rods 13. The pistons 12 and the connecting rods 13 are provided for each cylinder 11.

[0019] The cylinder 11 is a space partitioned in the cylinder block 25. The cylinder 11 is a space where the mixture of fuel and intake air burns. The crank chamber 28 is a space partitioned by the crankcase 26 and the oil pan 27. The crank chamber 28 is located below when viewed from the cylinder 11. The crank chamber 28 communicates with each cylinder 11. At the bottom of the crank chamber 28, that is, at the bottom of the oil pan 27, lubricating oil for lubricating various parts of the internal combustion engine 10 accumulates. The piston 12 is located in the cylinder 11. The piston 12 reciprocates. The piston 12 is connected to the crankshaft 14 via the connecting rod 13. The crankshaft 14 is located in the crank chamber 28. The crankshaft 14 rotates in response to the reciprocating motion of the piston 12.

[0020] Although illustration is omitted, the internal combustion engine 10 has a water jacket. The water jacket is a passage through which cooling water flows. The water jacket is located around a plurality of cylinders 11.

[0021] The internal combustion engine 10 has a plurality of spark plugs 19. Note that in FIG. 2, only one of the plurality of spark plugs 19 is shown. The spark plug 19 is provided for each cylinder 11. The tip of the spark plug 19 is located in the cylinder 11. The spark plug 19 ignites the mixture of intake air and fuel.

[0022] The internal combustion engine 10 has a plurality of fuel injection valves 17. Note that in FIG. 2, only one of the plurality of fuel injection valves 17 is shown. The fuel injection valve 17 is provided for each cylinder 11. The tip of the fuel injection valve 17 is located in the cylinder 11. The fuel injection valve 17 injects fuel directly into the cylinder 11 without passing through the intake passage 15 described later.

[0023] The internal combustion engine 10 has an intake passage 15, a throttle valve 16, an exhaust passage 21, and a three-way catalyst 22. The intake passage 15 is a passage for introducing intake air into each cylinder 11. The intake passage 15 is connected to each cylinder 11. The throttle valve 16 is located in the middle of the intake passage 15. The throttle valve 16 is adjustable in opening degree. The amount of intake air (hereinafter referred to as the intake air amount) GA changes according to the opening degree of the throttle valve 16. The exhaust passage 21 is a passage for discharging exhaust from each cylinder 11. The exhaust passage 21 is connected to each cylinder 11. The three-way catalyst 22 is located in the middle of the exhaust passage 21. The three-way catalyst 22 purifies the exhaust.

[0024] The internal combustion engine 10 has a blow-by gas reflux mechanism. The blow-by gas reflux mechanism is a mechanism for refluxing blow-by gas, which is gas that has leaked into the crankcase 28 through the space between the wall surface partitioning the cylinder 11 in the cylinder block 25 and the piston 12, into the intake passage 15. The blow-by gas reflux mechanism has a first blow-by gas passage 31, a second blow-by gas passage 32, and a PCV valve 33. The first blow-by gas passage 31 communicates the crankcase 28 with the upstream portion of the intake passage 15 as viewed from the throttle valve 16. The second blow-by gas passage 32 communicates the crankcase 28 with the downstream portion of the intake passage 15 as viewed from the throttle valve 16. The PCV valve 33 is located in the middle of the second blow-by gas passage 32. The PCV valve 33 switches from the closed valve state to the open valve state when the pressure of the gas on the downstream side of the throttle valve 16 in the intake passage 15 (hereinafter referred to as the downstream pressure) P becomes lower than a predetermined specified pressure PM. When the PCV valve 33 is in the open valve state, blow-by gas flows from the crankcase 28 to the intake passage 15 in the second blow-by gas passage 32. At this time, intake air flows from the intake passage 15 to the crankcase 28 in the first blow-by gas passage 31.

[0025] The internal combustion engine 10 includes a crank sensor 80, an air flow meter 81, a pressure sensor 82, an air-fuel ratio sensor 83, a water temperature sensor 84, and an oil temperature sensor 85. The crank sensor 80 detects the rotational position CR of the crankshaft 14. The air flow meter 81 detects the intake air amount GA. The pressure sensor 82 detects the downstream pressure P in the intake passage 15. The air-fuel ratio sensor 83 detects the air-fuel ratio AF of the exhaust gas on the upstream side as viewed from the three-way catalyst 22 in the exhaust passage 21. The water temperature sensor 84 detects the temperature of the cooling water (hereinafter referred to as the coolant temperature) W at the outlet of the water jacket. The oil temperature sensor 85 detects the temperature L of the lubricating oil accumulated in the oil pan 27. Each of these sensors repeatedly outputs a signal corresponding to the information it has detected to a control device 100 described later.

[0026] <Schematic Configuration of Control Device> As shown in FIG. 1, the vehicle 500 includes a control device 100. The control device 100 can be configured as one or more processors that execute various processes according to a computer program (software). Note that the control device 100 may be configured as a circuit (circuitry) including one or more dedicated hardware circuits such as an application specific integrated circuit (ASIC) that executes at least some of the various processes, or a combination thereof. The processor includes a CPU 110 and memories such as a RAM 130 and a ROM 120. The memory stores program codes or instructions configured to cause the CPU 110 to execute processes. The memory, that is, the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. The control device 100 has an electrically rewritable non-volatile memory 140. The control device 100 performs various processes described below by the CPU 110 executing the program stored in the ROM 120.

[0027] The control device 100 repeatedly receives signals from various sensors of the vehicle 500. The control device 100 also receives a signal U from the power switch 60. When the control device 100 receives the signal U corresponding to the power switch 60 being turned on, it electrically connects the battery 206 and the motor generator 200. By doing so, the control device 100 makes the vehicle 500 in a state where it can travel. Hereinafter, the period from when the power switch 60 is turned on until it is turned off next is referred to as "one trip".

[0028] The control device 100 controls various parts of the vehicle 500. During one trip, the control device 100 grasps the state of the vehicle 500 and the driver's instructions based on the detection signals of various sensors. Then, the control device 100 controls various parts of the vehicle 500 based on the grasped information. The control device 100 stops the operation of the internal combustion engine 10 according to the situation and drives only the motor generator 200, or drives both the internal combustion engine 10 and the motor generator 200. In the latter case, the control device 100 directly connects the crankshaft 14 and the rotating shaft 200A of the motor generator 200 by the drive clutch 210. When the vehicle is stopped, the control device 100 basically intermittently stops the internal combustion engine 10, but continues the operation of the internal combustion engine 10 when any one of a plurality of predetermined prohibited conditions is satisfied. The prohibited conditions are, for example, that the warm-up of the internal combustion engine 10 is not completed, that is, the coolant temperature W is below a predetermined warm-up completion temperature, that various diagnoses of the internal combustion engine 10 are being executed, that various learning processes of the internal combustion engine 10 are being executed, and the like. The control device 100 stores a plurality of prohibited conditions in advance. When the control device 100 continues the operation of the internal combustion engine 10 during vehicle stop, the control device 100 controls the internal combustion engine 10 to an idle operation state. The idle operation state means operating the internal combustion engine 10 at the minimum rotational speed of the crankshaft 14 at which the internal combustion engine 10 can operate independently. Even during the idle operation of the internal combustion engine 10, the control device 100 directly connects the crankshaft 14 and the rotating shaft 200A of the motor generator 200 by the drive clutch 210 as described above. In addition, the control device 100 appropriately switches the gear position of the automatic transmission 240 to an optimal one.

[0029] <Control of the Launch Clutch> On the premise that the D range or R range is selected by the shift device 290, the control device 100 switches the control state of the starting clutch 220 as follows according to the vehicle speed SP, the brake operation amount BK, etc. When the vehicle 500 is running, the control device 100 controls the starting clutch 220 in a directly connected state. When the vehicle is stopped and the brake operation amount BK is less than or equal to a predetermined specified operation amount BKM, that is, when the brake operation amount BK is relatively small, the control device 100 controls the starting clutch 220 in a slip state. Note that the control device 100 also controls the starting clutch 220 in a slip state when the vehicle speed SP is below a specified vehicle speed SPM which is extremely low, such as just before stopping or at the time of starting of the vehicle 500. When the vehicle is stopped and the brake operation amount BK is greater than the above, the control device 100 controls the starting clutch 220 in a disengaged state.

[0030] Here, when the starting clutch 220 is in a slip state, the torque on the internal combustion engine 10 side as viewed from the starting clutch 220 can be transmitted to the automatic transmission 240 and then to the drive wheels 260. The above-mentioned specified operation amount BKM is predetermined as the maximum value of the brake operation amount BK that needs to actuate a corresponding torque on the drive wheels 260 for the prompt start of the vehicle 500 after the brake pedal is released. The above torque is a so-called creep torque input to the drive wheels 260 when the accelerator operation amount ACC is "0". The above-mentioned specified vehicle speed SPM is predetermined as the maximum value of the range of the vehicle speed SP in which the torque fluctuations of the internal combustion engine 10 and the motor generator 200 accompanying the switching between the stopped state and the running state should be suppressed from being transmitted to the drive wheels 260. The above-mentioned specified vehicle speed SPM is, for example, 5 km / h.

[0031] When controlling the starting clutch 220 to be in any of the above three states, the control device 100 substantially controls the hydraulic circuit 270. For example, when the control device 100 controls the starting clutch 220 to be in a slip state, it controls the valves and pumps in the hydraulic circuit 270 so that the hydraulic pressure supplied to the starting clutch 220 is smaller than that in the direct connection state and larger than that in the disconnection state. At this time, the control device 100 outputs, for example, a command value for the hydraulic pressure, a switching signal for the valve, or a drive signal for the pump. The process in which the control device 100 controls the starting clutch 220 to be in a slip state through the above control of the hydraulic circuit 270 during parking, immediately before parking, and starting is the second process.

[0032] <Calculation process of diluted fuel amount> In the internal combustion engine 10, part of the fuel injected from the fuel injection valve 17 may adhere to the wall surface that partitions the cylinder 11 in the cylinder block 25 (hereinafter referred to as the wall surface of the cylinder 11). Then, this fuel may mix into the crank chamber 28 from the gap between the piston 12 and the above wall surface as the piston 12 reciprocates. This fuel mixes into the lubricating oil accumulated at the bottom of the oil pan 27. If such a situation where the fuel mixes into the lubricating oil continues, the fuel dilution of the lubricating oil progresses. At the same time, the diluted fuel amount D, which is the amount of fuel contained in the lubricating oil, increases. On the other hand, when the temperature L of the lubricating oil rises, the fuel mixed in the lubricating oil vaporizes. At the same time, the diluted fuel amount D decreases. The vaporized fuel flows into the intake passage 15 through the second blow-by gas passage 32.

[0033] The control device 100 is capable of executing a first process which is a process for calculating an estimated value of the diluted fuel quantity D. The first process is composed of three processes: an addition value process, a subtraction value process, and an update process. The addition value process is a process for calculating an estimated addition dilution quantity Dad which is the quantity of fuel newly mixed into the lubricating oil. The subtraction value process is a process for calculating an estimated subtraction dilution quantity Dsub which is the quantity of fuel vaporized from the lubricating oil. The update process is a process for updating the diluted fuel quantity D according to the addition value process and the subtraction value process. Note that, as will be described later, the control device 100 stores the diluted fuel quantity D in the non-volatile memory 140 in relation to the update process.

[0034] <Addition value process> The control device 100 performs this addition value process once per trip. When either of the following conditions (A1) or (A2) is satisfied during one trip, the control device 100 executes the addition value process. Note that hereinafter, the first start of the internal combustion engine 10 in one trip is referred to as "first start".

[0035] (A1) The integrated value of the intake air quantity GA from the first start of the internal combustion engine 10 (hereinafter referred to as the intake air quantity after start) SGA has increased to the determination intake air quantity. (A2) The power switch 60 has been turned off before condition (A1) is satisfied during one trip.

[0036] (A1) above is set for the following reasons. The amount of fuel mixed into the lubricating oil gradually increases when the internal combustion engine 10 is started. On the other hand, when the temperature of the cylinder 11 rises to a specified temperature or higher due to the thermal energy generated by the combustion of the air-fuel mixture, no more fuel is mixed into the lubricating oil. This is because when the temperature of the cylinder 11 becomes high, the fuel supplied to the cylinder 11 vaporizes before adhering to the wall surface of the cylinder 11. The post-start intake air amount SGA is a parameter correlated with the total amount of thermal energy generated by the combustion of the air-fuel mixture in the cylinder 11 after the first start of the internal combustion engine 10. Therefore, when the post-start intake air amount SGA increases to the determination intake air amount, the control device 100 calculates the addition dilution amount Dad in the addition value process at that time. The determination intake air amount is a value that can be regarded as the temperature of the cylinder 11 reaching the specified temperature, and is determined in advance by, for example, experiments or simulations. The control device 100 stores the determination intake air amount in advance. Note that the above (A2) is set in consideration of the case where one trip is short.

[0037] In the addition value process, the control device 100 calculates the addition dilution amount Dad using the following (Equation 1). (Equation 1) Addition dilution amount Dad = Addition basic value DadK × First correction coefficient K1 In the above (Equation 1), the addition basic value DadK is the base value of the addition dilution amount Dad. The control device 100 calculates this addition basic value DadK based on the post-start intake air amount SGA described above. The post-start intake air amount SGA is correlated with the integrated value of the amount of fuel supplied to the cylinder 11 after the first start of the internal combustion engine 10. Therefore, the larger the post-start intake air amount SGA, the larger the amount of fuel adhering to the wall surface of the cylinder 11. Accordingly, the amount of fuel mixed into the lubricating oil also increases. Considering this point, the control device 100 calculates the addition basic value DadK as a larger value as the post-start intake air amount SGA increases.

[0038] Further, when calculating the addition basic value DadK, the control device 100 also takes into account the accumulated value of the operation time of the internal combustion engine 10 from the time when the internal combustion engine 10 is first started, which is the operation time after startup. Here, as the operation time after startup increases and the temperature of the cylinder 11 rises, the amount of fuel that once adheres to the wall surface of the cylinder 11 but then quickly vaporizes increases. Therefore, the amount of fuel finally mixed into the lubricating oil decreases. Considering this point, the control device 100 calculates the addition basic value DadK as a smaller value as the operation time after startup is longer.

[0039] The control device 100 calculates the first correction coefficient K1 based on the water temperature at startup Ws. The water temperature at startup Ws is the cooling water temperature W at the first startup of the internal combustion engine 10. Here, the lower the water temperature at startup Ws, the lower the temperature of the wall surface of the cylinder 11 at the first startup of the internal combustion engine 10. In this case, the fuel adhering to the wall surface of the cylinder 11 is difficult to vaporize. Therefore, the amount of fuel mixed into the lubricating oil increases. Considering this point, the control device 100 calculates the first correction coefficient K1 as a larger value as the water temperature at startup Ws is lower.

[0040] <Subtraction value process> The control device 100 repeatedly performs the subtraction value process at a predetermined cycle during one trip. In the subtraction value process, the control device 100 calculates the subtraction dilution amount Dsub as an estimated value of the amount of fuel vaporized from the lubricating oil between the previous execution and the next execution of the subtraction value process. In the subtraction value process, the control device 100 calculates the subtraction dilution amount Dsub using the following (Equation 2).

[0041] (Equation 2) Subtraction dilution amount Dsub = Subtraction basic value DsubK × Second correction coefficient K2 In the above (Formula 2), the subtraction basic value DsubK is the base value of the subtraction dilution amount Dsub. The control device 100 calculates this subtraction basic value DsubK based on the previous value Dold, which is the current dilution fuel amount D stored in the non-volatile memory 140. Here, the greater the amount of fuel in the lubricating oil, the greater the amount of fuel vaporized from the lubricating oil during the execution interval of the subtraction value process. Considering this point, the control device 100 calculates the subtraction basic value DsubK as a larger value as the previous value Dold is larger.

[0042] Regarding the second correction coefficient K2, the control device 100 calculates it based on the temperature L of the lubricating oil. Here, the higher the temperature L of the lubricating oil, the greater the amount of fuel vaporized from the lubricating oil. And the amount of fuel contained in the lubricating oil decreases. Considering this point, the control device 100 calculates the second correction coefficient K2 as a larger value as the current temperature L of the lubricating oil is higher.

[0043] <Update Process> After the control device 100 finishes executing the addition value process or the subtraction value process, it performs the update process each time. When the control device 100 performs the update process upon completion of the addition value process, it adds the addition dilution amount Dad calculated in the addition value process to the previous value Dold of the dilution fuel amount D stored in the non-volatile memory 140. Then, the control device 100 overwrites the value stored until then with the obtained value. When the control device 100 performs the update process upon completion of the subtraction value process, it subtracts the subtraction dilution amount Dsub calculated in the subtraction value process from the previous value Dold. Then, it overwrites the previous value with the obtained value.

[0044] Through the above addition value process, subtraction value process, and update process, the control device 100 sequentially updates the dilution fuel amount D during one trip. As described above, when calculating the dilution fuel amount D, the control device 100 uses parameters indicating the operating state of the internal combustion engine 10, such as the intake air amount SGA after startup, the operating time after startup, the coolant temperature Ws at startup, and the temperature L of the lubricating oil. That is, the control device 100 calculates the dilution fuel amount D based on the operating state of the internal combustion engine 10.

[0045] <Regarding Processing During Parking> When the control device 100 continues the idling operation state of the internal combustion engine 10 during parking, as dedicated processing, it can execute two types of processing. One of these two is referred to as normal processing, and the other is referred to as third processing. The control device 100 selects either the normal processing or the third processing according to whether the set conditions are satisfied. Note that the normal processing is processing for controlling both the internal combustion engine 10 and the motor generator 200. The third processing is also processing for controlling both the internal combustion engine 10 and the motor generator 200.

[0046] The set conditions are that all of the following three items (B1) to (B3) are satisfied. (B1) The diluted fuel amount D is equal to or greater than the determination value DM. (B2) The temperature L of the lubricating oil is equal to or higher than the specified oil temperature LM.

[0047] (B3) The downstream pressure P in the intake passage 15 is lower than the specified pressure PM. Regarding the specified pressure PM, it is as already described in relation to the PCV valve 33. The specified oil temperature LM is predetermined as a temperature at which it can be considered that the fuel mixed in the lubricating oil starts to vaporize. The specified oil temperature LM is, for example, 80°C. Now, as described above, when fuel vaporizes from the lubricating oil, the vaporized fuel returns to the intake passage 15 via the second blow-by gas passage 32 together with the blow-by gas. This fuel eventually reaches the cylinder 11. In this case, in the cylinder 11, in addition to the fuel supplied from the fuel injection valve 17, there is the fuel that has returned to the intake passage 15 together with the blow-by gas. From this, the air-fuel ratio of the air-fuel mixture in the cylinder 11 (hereinafter, simply referred to as the air-fuel ratio of the cylinder 11) AF can become richer than the theoretical air-fuel ratio AFs. The above determination value DM is, as the minimum value of the diluted fuel amount D that is so large that the influence on the air-fuel ratio AF of the cylinder 11 cannot be ignored when fuel vaporizes from the lubricating oil according to the temperature L of the lubricating oil and requires countermeasures, predetermined in advance by, for example, experiments or simulations. The control device 100 stores these determination value DM, specified oil temperature LM, and specified pressure PM in advance.

[0048] During one trip, the control device 100 constantly monitors the latest value of the vehicle speed SP. When the vehicle speed SP switches from a state greater than "0" to "0" and the prohibition condition for the intermittent stop of the internal combustion engine 10 is satisfied at that time, the control of the internal combustion engine 10 and the motor generator 200 is shifted to normal processing or third processing. At that time, the control device 100 determines whether the set conditions are satisfied based on the latest diluted fuel amount D stored by itself, the latest lubricating oil temperature L received from the oil temperature sensor 85, and the latest downstream pressure P received from the pressure sensor 82. If the set conditions are not satisfied, the control device 100 starts normal processing. If the set conditions are satisfied, the control device 100 starts third processing. Once the control device 100 starts normal processing, it continues the normal processing while the vehicle speed SP is "0". When the vehicle speed SP becomes greater than "0", the control device 100 ends the normal processing. For example, when the brake pedal is released, creep torque acts on the drive wheels 260, and the vehicle speed SP becomes greater than "0". Similar to the normal processing, the control device 100 also continues the third processing until the vehicle speed SP becomes greater than "0". After the end of the normal processing or the third processing, the control device 100 shifts the control of the internal combustion engine 10 and the motor generator 200 to other processing. Since the situation where the control device 100 executes normal processing or third processing is during a stop, the starting clutch 220 is in a slip state or a disengaged state during the execution of these processes.

[0049] <Normal processing> In normal processing, the control device 100 first sets target values for the control of various parts of the internal combustion engine 10. The control device 100 also sets a target motor torque MTg, which is the target value of the torque of the motor generator 200. The control device 100 quickly sets these target values. After setting each target value, the control device 100 controls the internal combustion engine 10 and the motor generator 200 based on those target values. The control device 100 continues to control the internal combustion engine 10 and the motor generator 200 based on each target value until the normal processing ends.

[0050] In normal processing, the control device 100 sets each target value for the internal combustion engine 10 as follows. The control device 100 sets the target ignition timing Fg of the spark plug 19 to the normal ignition timing Fn. The control device 100 sets the target opening Hg of the throttle valve 16 to the normal opening Hn. The control device 100 sets the target injection amount Jg from one fuel injection valve 17 in one cycle of the internal combustion engine 10 to the normal injection amount Jn. One cycle of the internal combustion engine 10 is a series of periods in which one cylinder 11 experiences an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke once each. The normal ignition timing Fn, the normal opening Hn, and the normal injection amount Jn are adjusted with respect to each other so that the air-fuel ratio AF of the cylinder 11 can be made the stoichiometric air-fuel ratio AFs and the rotational speed of the crankshaft 14 can be made a predetermined target idle rotational speed. The control device 100 stores these normal ignition timing Fn, normal opening Hn, and normal injection amount Jn in advance. Here, the minimum value of the fuel injection amount per injection allowed for one fuel injection valve 17 is called the minimum injection amount Jm. The normal injection amount Jn is slightly more than the minimum injection amount Jm. Also, the ignition timing at which the maximum torque can be obtained for a certain intake air amount GA is called the MBT ignition timing. The normal ignition timing Fn is, for example, the MBT ignition timing. In the following description, the intake air amount GA when the opening of the throttle valve 16 is the normal opening Hn is called the normal air amount GAn. Also, the torque of the internal combustion engine 10 when various target values for the internal combustion engine 10 are set as described above is called the normal torque ETn. The control device 100 stores the normal air amount GAn and the normal torque ETn in advance as information necessary for the third process described later.

[0051] In normal processing, the control device 100 of the present embodiment sets the target motor torque MTg to "0". Note that the control device 100 treats the driving torque as a positive value and the regenerative torque as a negative value.

[0052] <Third Process> In the third process, the control device 100 sets various target values and controls the internal combustion engine 10 and the motor generator 200 based on those target values, just as in the normal process. In the third process, the control device 100 controls the throttle valve 16 so that the intake air amount GA increases and controls the motor generator 200 so that the power generation amount increases, compared with the normal process. Hereinafter, the details of the third process will be described. Note that when executing the third process, the control device 100 promptly performs the processes of the following step S10 to step S60, which are the processes of setting each target value. Thereafter, the control device 100 continues the process of step S70 until the above-described end condition related to the vehicle speed SP is satisfied.

[0053] When starting the third process, the control device 100 first executes the process of step S10. As shown in FIG. 3, in step S10, the control device 100 sets the target injection amount Jg. The control device 100 sets the above-described minimum injection amount Jm as the target injection amount Jg. The control device 100 stores the minimum injection amount Jm in advance. When setting the target injection amount Jg, the control device 100 advances the process to step S20.

[0054] In step S20, the control device 100 calculates the return fuel amount R. The return fuel amount R is an estimated value of the amount of fuel that returns to the intake passage 15 together with the blow-by gas through the second blow-by gas passage 32 in a certain unit time. The unit time is, for example, the length of time required for one cycle of the internal combustion engine 10. The control device 100 stores a first map in advance as information for calculating the return fuel amount R. The first map represents the relationship between the downstream pressure P in the intake passage 15 and the return fuel amount R. Here, the lower the downstream pressure P, the larger the amount of blow-by gas returned to the intake passage 15 through the second blow-by gas passage 32. Along with that, the return fuel amount R also increases. Reflecting such a relationship, in the first map, the lower the downstream pressure P, the larger the return fuel amount R. Note that this first map is created based on, for example, experiments or simulations on the premise that the setting conditions are satisfied. The control device 100 calculates, as the current return fuel amount R, the return fuel amount R corresponding to the latest downstream pressure P received from the pressure sensor 82 based on this first map. After that, the control device 100 proceeds to the process in step S30.

[0055] In step S30, the control device 100 sets the target opening Hg of the throttle valve 16. On this premise, the control device 100 calculates the target air quantity GAg which is the target value of the intake air quantity GA. Specifically, when assuming that the fuel injection valve 17 injects the minimum injection quantity Jm and the return fuel quantity R is equally distributed to each cylinder 11, the control device 100 calculates the required air quantity GAy which is the intake air quantity GA required to make the air-fuel ratio AF of each cylinder 11 the theoretical air-fuel ratio AFs. The control device 100 sets this required air quantity GAy as the target air quantity GAg. After calculating the target air quantity GAg, the control device 100 sets the opening of the throttle valve 16 required to achieve the target air quantity GAg as the target opening Hg. The larger the target air quantity GAg is, the larger the value of the target opening Hg is. After that, the control device 100 advances the process to step S40. Here, the magnitude relationship between the above-mentioned required air quantity GAy and the above-mentioned normal air quantity GAn will be explained. The normal air quantity GAn is approximately the same as the intake air quantity GA required to make the air-fuel ratio AF of the cylinder 11 the theoretical air-fuel ratio AFs when the fuel injection quantity of the fuel injection valve 17 is the minimum injection quantity Jm. Therefore, compared with this normal air quantity GAn, the above-mentioned required air quantity GAy is larger by the amount taking into account the return fuel quantity R.

[0056] In step S40, the control device 100 calculates the incremental torque ΔET. Here, assume that the current intake air amount GA is the required air amount GAy, ignition is performed at the normal ignition timing Fn, and the internal combustion engine 10 is operated in a state where the minimum injection amount Jm and an equal amount of the return fuel amount R are supplied to each cylinder 11. The estimated value of the torque generated by the internal combustion engine 10 at this time is called the specific torque ETy. The incremental torque ΔET described above is the increase in the specific torque ETy with respect to the normal torque ETn. The control device 100 stores a second map in advance as information for calculating the incremental torque ΔET. The second map represents the relationship between the torque of the internal combustion engine 10 and the intake air amount GA. This second map is created based on, for example, experiments or simulations on the premise that the air-fuel ratio AF of the cylinder 11 is the theoretical air-fuel ratio AFs and the ignition timing of the ignition plug 19 is the normal ignition timing Fn. In the second map, basically, the greater the intake air amount GA, the greater the torque of the internal combustion engine 10. The control device 100 calculates the torque of the internal combustion engine 10 corresponding to the required air amount GAy as the specific torque ETy based on this second map. After that, the control device 100 calculates the value obtained by subtracting the normal torque ETn from the specific torque ETy as the incremental torque ΔET. After that, the control device 100 advances the process to step S50.

[0057] In step S50, the target motor torque MTg is set. As a prerequisite, the control device 100 calculates a provisional value of the target motor torque MTg (hereinafter referred to as the provisional torque). Specifically, the control device 100 sets, as the provisional torque MTg1, the regenerative torque required to cancel out the above-mentioned incremental torque ΔET. That is, the control device 100 sets the value obtained by multiplying the incremental torque ΔET by "-1" as the provisional torque MTg1. After that, the control device 100 compares this provisional torque MTg1 with the limit torque MTg2 of the motor generator 200. The limit torque MTg2 is the regenerative torque corresponding to the maximum power generation amount of the motor generator 200, which is determined from the specifications of the motor generator 200. That is, the maximum power generation amount and the limit torque MTg2 are limit values determined in advance for each product. The control device 100 stores the maximum power generation amount and the limit torque MTg2 in advance. Note that since the limit torque MTg2 is a regenerative torque, it is a negative value. The control device 100 sets the larger of the provisional torque MTg1 and the limit torque MTg2 as the target motor torque MTg. That is, the target motor torque MTg becomes a value equal to or greater than the limit torque MTg2. When the control device 100 calculates the target motor torque MTg, the process proceeds to step S60.

[0058] In step S60, the control device 100 sets the target ignition timing Fg. When the control device 100 sets the provisional torque MTg1 as the target motor torque MTg in step S50, it sets the normal ignition timing Fn as the target ignition timing Fg. On the other hand, when the control device 100 sets the limit torque MTg2 as the target motor torque MTg in step S50, it sets the target ignition timing Fg as follows. First, the control device 100 calculates a value obtained by subtracting the absolute value of the limit torque MTg2 from the absolute value of the provisional torque MTg1 as the differential torque ΔMT. The control device 100 calculates the retard amount of the ignition timing required to reduce the torque of the internal combustion engine 10 by this differential torque ΔMT. Then, the control device 100 sets the timing retarded by this retard amount from the normal ignition timing Fn as the target ignition timing Fg. As information for calculating the above retard amount, the control device 100 stores a third map in advance. The third map represents the relationship between the retard amount of the ignition timing and the decrease amount of the torque of the internal combustion engine 10 corresponding thereto. Note that the relationship between the retard amount of the ignition timing and the decrease amount of the torque of the internal combustion engine 10 can be regarded as generally the same even if the air-fuel ratio AF of the cylinder 11 is large or small. The third map is created based on, for example, experiments or simulations. In the third map, basically, the larger the retard amount, the larger the decrease amount of the torque of the internal combustion engine 10. The control device 100 calculates the retard amount corresponding to the above differential torque ΔMT in this third map. Then, the control device 100 sets the target ignition timing Fg as described above using this retard amount. When the control device 100 sets the target ignition timing Fg, it proceeds with the process to step S70.

[0059] In step S70, the control device 100 controls the internal combustion engine 10 and the motor generator 200 based on each target value calculated in the processing so far. Specifically, the control device 100 controls the throttle valve 16 so that the target opening Hg set in step S30 matches the actual opening of the throttle valve 16. Further, the control device 100 performs fuel injection and ignition in each cylinder 11 in order to burn the air-fuel mixture in each cylinder 11. At this time, the control device 100 controls each fuel injection valve 17 to inject fuel with a target injection amount Jg set in step S10. Further, the control device 100 controls each spark plug 19 to perform ignition at the target ignition timing Fg set in step S60. While controlling the internal combustion engine 10 in this way, the control device 100 controls the motor generator 200 so that the target motor torque MTg set in step S50 matches the actual torque of the motor generator 200. As described above, the control device 100 continues the processing of step S70 while the vehicle speed SP is "0". Then, when the vehicle speed SP becomes greater than "0", the control device 100 ends the processing of step S70. After this, the control device 100 ends the series of processing of the third processing.

[0060] <Operation of the Embodiment> Assume that the vehicle 500 stops from time T1 to time T2 during one trip. At this time, for example, assume that the internal combustion engine 10 is in the middle of warm-up and is in a situation where the idle operation state of the internal combustion engine 10 continues. Also, at this time, assume that the set conditions are satisfied and the return fuel amount R is relatively large. In this case, the control device 100 controls the internal combustion engine 10 and the motor generator 200 by the third processing from time T1 to time T2. An example of the transition of each parameter at this time will be described. In this example, assume that a provisional torque MTg1 is set as the target motor torque MTg and the normal ignition timing Fn is set as the target ignition timing Fg. Also, assume that the brake operation amount BK is relatively small and the start clutch 220 is in a slip state.

[0061] In the above situation where the set conditions are satisfied, along with the large amount of return fuel R, the amount of fuel supplied to the cylinder 11 increases. Anticipating such an increase in fuel, in the third process, as shown in Fig. 4(a), the intake air amount GA is set to the required air amount GAy, which is larger than the normal air amount GAn. Accordingly, as shown in Fig. 4(b), the air-fuel ratio AF of the cylinder 11 is maintained at approximately the stoichiometric air-fuel ratio AFs. By this, the exhaust gas purification ability of the three-way catalyst 22 is kept in a high state.

[0062] Now, in consideration of setting the intake air amount GA to the required air amount GAy, the torque of the internal combustion engine 10 becomes a specific torque ETy, which is larger than the normal torque ETn, as shown in Fig. 4(c). To offset this increase in torque, in the third process, as shown in Fig. 4(e), a regeneration torque is applied to the motor generator 200 to generate electricity. In Fig. 4(e), the generated electricity amount corresponding to the provisional torque MTg1 is represented as V. When a regeneration torque is applied to the motor generator 200, the rotating shaft 200A of the motor generator 200 rotates while being dragged by the rotation of the crankshaft 14. At this time, the motor generator 200 is in a state where torque is input from the internal combustion engine 10. And the motor generator 200 generates electricity by that torque. On the other hand, from the viewpoint of the force acting on the crankshaft 14, a force in the direction opposite to the rotation direction of the crankshaft 14 acts on the crankshaft 14. Therefore, the crankshaft 14 is in a state where its rotation is hindered. Thus, an increase in the rotational speed of the crankshaft 14 is suppressed. Moreover, the regeneration torque applied to the motor generator 200 is set to a value that completely offsets the increase in torque of the internal combustion engine 10 associated with the required air amount GAy. Therefore, as shown in Fig. 4(d), the rotational speed of the crankshaft 14 and thus the rotating shaft 200A of the motor generator 200 connected to the crankshaft 14 becomes approximately the same as the target idle rotational speed NEg in the normal process.

[0063] As described above, the starting clutch 220 is in a slip state. Therefore, the rotating shaft 200A of the motor generator 200 connected via the starting clutch 220 and the input shaft 240A of the automatic transmission 240 are in a state of relative rotation. As described above, during the execution of the third process, the rotational speed of the rotating shaft 200A of the motor generator 200 is the same as that in the normal process. Therefore, the difference in rotational speed between the rotating shaft 200A of the motor generator 200 and the input shaft 240A of the automatic transmission 240 becomes substantially the same as that in the normal process.

[0064] <Effects of the Embodiment> (1) As described in the above operation, in this embodiment, it is possible to maintain a state in which the difference in rotational speed between the rotating shaft 200A of the motor generator 200 and the input shaft 240A of the automatic transmission 240 is within an allowable range. Therefore, the air-fuel ratio AF of the cylinder 11 can be maintained at the theoretical air-fuel ratio AFs, and seizure of the starting clutch 220 can be prevented.

[0065] (2) As described in step S50, in this embodiment, when the absolute value of the limit torque MTg2 of the motor generator 200 is smaller than the absolute value of the regenerative torque that cancels out the incremental torque ΔET, the limit torque MTg2 is selected as the target motor torque MTg. In this case, in accordance with this setting, the target ignition timing Fg of the ignition plug 19 in the internal combustion engine 10 is retarded (step S60). By doing so, the torque of the internal combustion engine 10 is reduced, and the increase in the torque of the internal combustion engine 10 is made to match the limit torque MTg2 of the motor generator 200. By adjusting the target ignition timing Fg of the ignition plug 19 in this way, the increase in the torque of the internal combustion engine 10 can be canceled out by the power generation of the motor generator 200 while maintaining the intake air amount GA at the required air amount GAy. By adopting such a configuration, even when there are restrictions on the power generation amount by the motor generator 200, the air-fuel ratio AF of the cylinder 11 can be maintained at the theoretical air-fuel ratio AFs, and seizure of the starting clutch 220 can be prevented.

[0066] <Modification Example> Note that the above embodiments can be implemented with the following modifications. The embodiments and the following modification examples can be implemented in combination with each other as long as they do not technically conflict with each other.

[0067] · When the starting clutch 220 is in the disengaged state, it will not seize. From this perspective, when the starting clutch 220 is in the disengaged state, the execution of the third process may be canceled. When the third process is canceled, normal processing may be performed.

[0068] · The execution period of the third process is not limited to the example of the above embodiment. The third process may be performed only during a part of the period while the vehicle is stopped. In addition to or instead of when the vehicle is stopped, the third process may be performed when the vehicle speed SP is greater than "0" and less than or equal to the specified vehicle speed SPM, such as before stopping or at the start. If the third process is performed when the starting clutch 220 is in a slip state, seizing of the starting clutch 220 can be prevented.

[0069] · The magnitude of the provisional torque MTg1 set in step S50 is not limited to the example of the above embodiment. As the provisional torque MTg1, a regenerative torque necessary to cancel only a part of the incremental torque ΔET may be set. For example, a value obtained by multiplying half of the incremental torque ΔET by "-1" may be used as the provisional torque MTg1. Even when such a provisional torque MTg1 is used as the target motor torque to generate electricity in the motor generator 200, the rotation of the crankshaft 14 can be hindered to a certain extent. Therefore, it is possible to prevent the rotational speed of the crankshaft 14 and thus the rotational axis 200A of the motor generator 200 from becoming excessively high. The provisional torque MTg1 may be set as the target motor torque MTg so that the amount of generated electricity is greater than that in normal processing.

[0070] · The method of setting the target motor torque MTg in the third process is not limited to being based on the provisional torque MTg1 and the limit torque MTg2 as in the above-described embodiment. For example, in the third process, the target motor torque MTg may be a predetermined fixed value. The target motor torque MTg may be changed during the execution of the third process. As long as the target motor torque MTg of the third process is set so that the power generation amount is larger than that in the normal process.

[0071] · The target air amount GAg set in the third process is not limited to the example of the above-described embodiment. For example, the target air amount GAg may be less than the required air amount GAy. Even in this case, as long as the target air amount GAg is set to be larger than the normal air amount GAn, the air-fuel ratio AF of the cylinder 11 can be made closer to the stoichiometric air-fuel ratio AFs. The target air amount GAg may be a predetermined fixed value. As long as the target air amount GAg set in the third process is larger than the normal air amount GAn.

[0072] · The target air amount GAg may be changed during the execution of the third process. For example, although the third process has started, due to errors such as the opening degree of the throttle valve 16 and the fuel injection amount of the fuel injection valve 17, the air-fuel ratio AF of the cylinder 11 may deviate slightly from the stoichiometric air-fuel ratio AFs. In this case, based on the detection value of the air-fuel ratio sensor 83, the target air amount GAg may be adjusted so that the air-fuel ratio AF of the cylinder 11 becomes the stoichiometric air-fuel ratio AFs. Then, the target motor torque MTg may be adjusted so as to cancel out the change in the torque of the internal combustion engine 10 accompanying the adjustment of the target air amount GAg. An example of the case where such an aspect is adopted will be described below.

[0073] In step S70 of the third process, the control device 100 performs the following process instead of the embodiment described above. That is, when the process proceeds to step S70, the control device 100 temporarily controls the internal combustion engine 10 and the motor generator 200 based on each target value calculated in steps S10 to S60. The control device 100 controls the internal combustion engine 10 and the motor generator 200 over a predetermined control period, such as several cycles of the internal combustion engine 10, which is a period required for the response of the air-fuel ratio AF to each target value to stabilize to a certain extent. After the elapse of that control period, the control device 100 repeats the calculation of each target value through the following steps S210 to S240 and the control of the internal combustion engine 10 and the motor generator 200 based on the calculated target values (step S250). In the following description, the previous value refers to each target value calculated by the control device 100 previously.

[0074] As shown in FIG. 5, first, in step S210, the control device 100 grasps the deviation ΔAF of the air-fuel ratio AF of the cylinder 11 from the stoichiometric air-fuel ratio AFs based on the latest air-fuel ratio AF received from the air-fuel ratio sensor 83. Then, the control device 100 calculates the change amount of the intake air amount GA required to eliminate this deviation ΔAF as the intake adjustment value ΔGA. The intake adjustment value ΔGA takes positive and negative values. That is, if the latest air-fuel ratio AF received from the air-fuel ratio sensor 83 is richer than the stoichiometric air-fuel ratio AFs, the control device 100 calculates the intake adjustment value ΔGA as a positive value. On the other hand, if the latest air-fuel ratio AF is leaner than the stoichiometric air-fuel ratio AFs, the control device 100 calculates the intake adjustment value ΔGA as a negative value. After that, the control device 100 sets the target opening Hg of the throttle valve 16 based on the intake adjustment value ΔGA. Specifically, the control device 100 sets the value obtained by adding the intake adjustment value ΔGA to the previous value of the target air amount as the new target air amount GAg. For example, when the intake adjustment value ΔGA is a positive value, the new target air amount GAg becomes larger than the previous value. When the control device 100 calculates the target air amount GAg, it sets the opening of the throttle valve 16 required to achieve this target air amount GAg as the new target opening Hg.

[0075] After that, in step S220, the control device 100 calculates an estimated value of the increase or decrease in the torque of the internal combustion engine 10 (hereinafter referred to as the changing torque) ΔETx corresponding to changing the intake air amount GA by the intake adjustment value ΔGA. The changing torque ΔETx is the increase or decrease in the torque of the internal combustion engine 10 when it is assumed that only the intake air amount GA is changed without changing other parameters other than the intake air amount GA. Note that changing the intake air amount GA by the intake adjustment value ΔGA means, for example, increasing the intake air amount GA if the intake adjustment value ΔGA is a positive value. If the intake adjustment value ΔGA is a positive value, the control device 100 calculates the changing torque ΔETx as a positive value. The fact that the changing torque ΔETx is positive means that the torque of the internal combustion engine 10 increases. If the intake adjustment value ΔGA is a negative value, the control device 100 calculates the changing torque ΔETx as a negative value. The fact that the changing torque ΔETx is negative means that the torque of the internal combustion engine 10 decreases. Basically, the control device 100 calculates the absolute value of the changing torque ΔETx as a larger value as the absolute value of the intake adjustment value ΔGA is larger. The control device 100 stores in advance, for example, a map representing the relationship between the change amount of the intake air amount GA and the change amount of the torque of the internal combustion engine 10 as information for calculating the changing torque ΔETx.

[0076] After that, in step S230, the control device 100 sets the target motor torque MTg. First, the control device 100 calculates an adjustment motor torque MTx, which is the torque of the motor generator 200 required to completely cancel out the change torque ΔETx. That is, the control device 100 sets the value obtained by multiplying the change torque ΔETx by "-1" as the adjustment motor torque MTx. The adjustment motor torque MTx takes positive and negative values according to the change torque ΔETx. After that, the control device 100 sets the value obtained by adding the adjustment motor torque MTx to the previous value of the target motor torque as the current provisional torque MTx1. Here, the previous value of the target motor torque is a negative value. And, compared with the absolute value of the previous value of the target motor torque, the absolute value of the adjustment motor torque MTx as an adjustment value is extremely small. Therefore, the current provisional torque MTx1, which is the value obtained by adding the adjustment motor torque MTx to the previous value of the target motor torque, becomes a negative value. When the control device 100 calculates the current provisional torque MTx1, the control device 100 compares the current provisional torque MTx1 with the limit torque MTg2. And, the control device 100 sets the larger of these as the latest target motor torque MTg. That is, similar to the above embodiment, the target motor torque MTg is a value equal to or greater than the limit torque MTg2. Note that the limit torque MTg2 is as described in the above embodiment.

[0077] After that, in step S240, the control device 100 sets the target ignition timing Fg. When the control device 100 sets the current provisional torque MTx1 as the latest target motor torque MTg in step S230, it sets the previous value of the target ignition timing as the latest target ignition timing Fg. On the other hand, when the control device 100 sets the limit torque MTg2 as the latest target motor torque MTg in step S230, it sets the latest target ignition timing Fg as follows. That is, the control device 100 calculates the current differential torque ΔMTr as the value obtained by subtracting the absolute value of the limit torque MTg2 from the absolute value of the current provisional torque MTx1. Then, the control device 100 calculates the retard amount of the ignition timing required to reduce the torque of the internal combustion engine 10 by this current differential torque ΔMTr. The control device 100 calculates the retard amount based on, for example, the above-mentioned third map. When the control device 100 calculates the retard amount, it sets the timing retarded by this retard amount from the previous value of the target ignition timing as the new target ignition timing Fg. After that, the control device 100 sets the previous value of the target injection amount as the target injection amount Jg. That is, the target injection amount Jg is the minimum injection amount Jm. The control device 100 promptly performs the processes of steps S210 to S240 above.

[0078] After that, in step S250, the control device 100 controls the internal combustion engine 10 and the motor generator 200 based on each target value over a predetermined control period. After that, the control device 100 returns to the process of step S210.

[0079] As described above, the control device 100 may perform feedback control on the internal combustion engine 10 and the motor generator 200 so as to eliminate the deviation between the actual air-fuel ratio AF of the cylinder 11 and the theoretical air-fuel ratio AFs. In the case of such a configuration, during the execution of the third process, the effects of (1) and (2) above can be obtained while surely maintaining the air-fuel ratio AF of the cylinder 11 at the theoretical air-fuel ratio AFs.

[0080] ·During the execution of the third process, the target injection amount Jg may be changed. For example, at the start of the third process, the target injection amount Jg is set to be greater than the minimum injection amount Jm. Then, during the execution of the third process, the target injection amount Jg may be decreased toward the minimum injection amount Jm according to the air-fuel ratio AF of the cylinder 11.

[0081] ·The prohibition conditions for prohibiting the intermittent stop of the internal combustion engine 10 during stoppage are not limited to those listed in the above embodiment. As a prohibition condition, a condition that the charge rate of the battery 206 is equal to or lower than a predetermined required charge rate may be adopted. This prohibition condition indicates the continuation of the operation of the internal combustion engine 10 for the purpose of charging the battery 206. Therefore, when the operation of the internal combustion engine 10 is continued because this prohibition condition is satisfied, it is necessary to take into account the following basic regeneration torque when setting the target motor torque MTg. The basic regeneration torque is the regeneration torque for realizing the power generation amount originally required from the battery 206 when the above prohibition condition is satisfied, regardless of the power generation for dealing with the return fuel from the crankcase 28. In taking this basic regeneration torque into account in the normal process and the third process, the following mode may be adopted. That is, when the normal process is performed when the above prohibition condition is satisfied, in the normal process, the above basic regeneration torque is set as the target motor torque MTg. On the other hand, when the third process is performed when the above prohibition condition is satisfied, in the third process, the sum of the above basic regeneration torque and the regeneration torque necessary to cancel out the increase in the torque of the internal combustion engine 10 for dealing with the return fuel is set as the final target motor torque MTg. Note that in consideration of the balance with the limit torque MTg2, the limit torque MTg2 may be set as the target motor torque MTg.

[0082] When it is necessary to take into account the above-described basic regeneration torque, the third process may be such that the following conditions are satisfied. That is, on the condition that the magnitude of the basic regeneration torque is the same, it is sufficient that the power generation amount of the third process is larger than that of the normal process. In addition, in order to grasp the charge rate of the battery 206, sensors for detecting the current, voltage, and temperature of the battery 206 may be provided around the battery 206. Then, the charge rate may be calculated based on the detection values of such sensors. The charge rate of the battery 206 is the ratio of the remaining capacity of the battery 206 to the full charge capacity of the battery 206.

[0083] · As described in the above modification example, the target motor torque MTg may not be "0". And the power generation amount in the normal process may be more than "0". · The setting conditions are not limited to the examples of the above embodiment. The item (B2) may be abolished from the setting conditions. Even if the temperature L of the lubricating oil is relatively low, the fuel mixed in the lubricating oil may vaporize. When such fuel returns to the intake passage 15 together with the blow-by gas, it affects the air-fuel ratio AF of the cylinder 11. The third process may be performed as a countermeasure against such returned fuel. The setting conditions only need to include the item (B1).

[0084] · The determination value DM related to the item (B1) is not limited to the examples of the above embodiment. For example, the determination value DM related to the item (B1) may be changed according to the presence or absence of the item (B2). The determination value DM may be determined as a value at which countermeasures against the returned fuel from the crank chamber 28 should be started from the viewpoint of suppressing the deviation of the actual air-fuel ratio AF of the cylinder 11 from the theoretical air-fuel ratio AFs.

[0085] · The method of calculating the diluted fuel amount D is not limited to the examples of the above embodiment. For example, when calculating the additive dilution amount Dad, a correction value may be added to or subtracted from the base value. Even in this case, the base value and the correction value may be appropriately set so that the additive dilution amount Dad can be appropriately calculated. The same applies to the subtractive dilution amount Dsub. As long as the diluted fuel amount D can be appropriately calculated based on the operating state of the internal combustion engine 10, the calculation method is not limited.

[0086] ·The temperature L of the lubricating oil may be calculated based on the operating state of the internal combustion engine 10. For example, the temperature L of the lubricating oil may be calculated based on parameters such as the integrated value of the cooling water temperature W and the intake air amount GA. As long as the temperature L of the lubricating oil can be appropriately calculated, the calculation method is not limited.

[0087] ·The overall configuration of the internal combustion engine 10 is not limited to the examples of the above embodiments. For example, the number of cylinders 11 may be changed. Further, the fuel injection valve 17 may be installed in the intake passage 15. And fuel may be supplied to the cylinder 11 through the intake passage 15. The internal combustion engine 10 only needs to have a cylinder 11, a crankcase 28, a throttle valve 16, and a blow-by gas passage for allowing blow-by gas to flow from the crankcase 28 to the intake passage 15.

[0088] ·The overall configuration of the vehicle 500 is not limited to the examples of the above embodiments. For example, as the automatic transmission, a continuously variable automatic transmission may be adopted. The vehicle only needs to have a motor generator, a starting clutch, and an automatic transmission in this order on the torque transmission path from the internal combustion engine to the drive wheels. And the starting clutch only needs to be able to switch to the three states described in the above embodiments. The starting clutch may be, for example, dry instead of wet.

Explanation of reference numerals

[0089] 10…Internal combustion engine 11…Cylinder 16…Throttle valve 28…Crankcase 32…Second blow-by gas passage 100…Control device 200…Motor generator 220…Starting clutch 240…Automatic transmission 500…Vehicle

Claims

【Claim 1】 An internal combustion engine including a cylinder which is a space where a mixture of fuel and intake air burns, a crank chamber communicating with the cylinder, a blow-by gas passage for allowing blow-by gas to flow from the crank chamber to an intake passage, and a throttle valve for adjusting the amount of the intake air; An automatic transmission including an input shaft; A motor generator which is located between the internal combustion engine and the automatic transmission on a torque transmission path and includes a rotating shaft, and which can generate electricity by torque input from the internal combustion engine; A starting clutch which is located between the motor generator and the automatic transmission on the torque transmission path, and in which the rotating shaft of the motor generator and the input shaft of the automatic transmission are switched to any one of a direct connection state where torque is transmitted without relative rotation, a slip state where torque is transmitted while relatively rotating, and a disconnection state where torque is not transmitted; A vehicle having the above components is a control target; A first process for calculating a diluted fuel amount which is the amount of fuel contained in the lubricating oil of the internal combustion engine based on the operating state of the internal combustion engine; A second process for controlling the starting clutch to the slip state when the traveling speed of the vehicle is equal to or lower than a predetermined vehicle speed; A third process for controlling the throttle valve so that the amount of the intake air increases and controlling the motor generator so that the power generation amount increases when the starting clutch is in the slip state and the diluted fuel amount is equal to or more than a predetermined determination value, as compared with the case where the starting clutch is in the slip state and the diluted fuel amount is less than the determination value; Executing A vehicle control device.

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