Hybrid vehicles

Abstract

To supply evaporated fuel to a combustion chamber without necessarily requiring a booster pump when starting an internal combustion engine.SOLUTION: A CPU executes intake gas flow rate adjustment processing, motoring processing, evaporated fuel adjustment processing, and first start processing. In the intake gas flow rate adjustment processing of a step S15, the CPU adjusts an opening of a throttle valve to an open state. In the motoring processing of a step S16, the CPU controls a first motor generator and makes an internal combustion engine perform motoring. In the evaporated fuel adjustment processing of a step S19, the CPU allows the evaporated fuel to flow through an evaporated fuel passage by adjusting an opening of an evaporated fuel adjustment valve during the motoring processing. In the first start processing of a step S21, the CPU starts the internal combustion engine by controlling and igniting an ignition device during the motoring processing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to hybrid vehicles. [Background technology]

[0002] Patent Document 1 describes a fuel supply device for an internal combustion engine. The fuel supply device includes a fuel tank that stores fuel, an evaporated fuel passage that flows evaporated fuel generated in the fuel tank together with air into the combustion chamber of the internal combustion engine, and a boost pump provided in the evaporated fuel passage. The fuel supply device also includes a control device that controls the boost pump. When starting the internal combustion engine, this control device drives the boost pump to flow evaporated fuel generated in the fuel tank toward the combustion chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-343365 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a boost pump is required to supply evaporated fuel to the combustion chamber. This increases the cost of the boost pump and requires space to install the boost pump. Therefore, there is a need for a technology that can supply evaporated fuel to the combustion chamber without necessarily requiring a boost pump when starting an internal combustion engine. [Means for solving the problem]

[0005] In order to achieve the above object, the present invention provides an internal combustion engine as a driving source, the internal combustion engine having an engine body having a combustion chamber, a fuel injection device that supplies liquid fuel to the combustion chamber, an ignition device that ignites liquid fuel to cause combustion in the combustion chamber, an intake passage connected to the combustion chamber and flowing intake gas into the combustion chamber, and a throttle valve provided in the intake passage and adjusting the intake gas flow rate, which is the flow rate of the intake gas; an evaporated fuel passage that connects a fuel tank to a portion of the intake passage downstream of the throttle valve and upstream of the combustion chamber and flows evaporated fuel generated in the fuel tank together with air into the intake passage; an evaporated fuel adjustment valve provided in the evaporated fuel passage and adjusting the opening of the evaporated fuel passage; a control device that controls the starting of the internal combustion engine by controlling the ignition device, the throttle valve, the evaporated fuel control valve, and the motor generator, wherein the control device executes an intake gas flow rate adjustment process that controls the opening of the throttle valve to an open state, a motoring process that controls the motor generator to motor the internal combustion engine, an evaporated fuel adjustment process that adjusts the opening of the evaporated fuel control valve during the motoring process to allow the evaporated fuel to flow through the evaporated fuel passage, and a start process that controls the ignition device to ignite during the motoring process to start the internal combustion engine.

[0006] According to the above configuration, the evaporated fuel can be supplied to the combustion chamber by the negative pressure generated by motoring. Then, the amount of evaporated fuel supplied to the combustion chamber can be controlled to an amount suitable for starting the internal combustion engine by the evaporated fuel adjustment process. Therefore, when burning the evaporated fuel to start the internal combustion engine, it is not necessary to use a device solely for supplying evaporated fuel, such as a boost pump. [Brief explanation of the drawings]

[0007] [Figure 1]FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 2 is a schematic diagram of a hybrid vehicle. [Figure 3] FIG. 3 is a flowchart showing a part including the first start process among a series of processes of the internal combustion engine start program. [Figure 4] FIG. 4 is a flowchart showing a part including the second start process among a series of processes of the internal combustion engine start program. [Figure 5] FIG. 5 is a flowchart showing a part of the series of processes in the internal combustion engine start program, including the process to be performed when the maximum supply amount is less than the required amount. [Figure 6] FIG. 6 is a flowchart showing a part of the series of processes in the internal combustion engine starting program, which includes the process to be performed when the intake negative pressure does not reach the required negative pressure. DETAILED DESCRIPTION OF THE INVENTION

[0008] (One embodiment) Hereinafter, an embodiment of a hybrid vehicle will be described with reference to the drawings. <Hybrid vehicle configuration> First, the general configuration of the hybrid vehicle 100 will be described.

[0009] 1, hybrid vehicle 100 includes a spark-ignition internal combustion engine 10 as a drive source. Hybrid vehicle 100 also includes a first motor generator 71 and a second motor generator 72 that function as both an electric motor and a generator. Therefore, hybrid vehicle 100 is a so-called hybrid vehicle.

[0010] The internal combustion engine 10 has an engine body 11. The engine body 11 is equipped with a plurality of cylinders 12 and a crankshaft 13. The cylinders 12 are spaces for burning a mixture of fuel and intake gas. The engine body 11 includes four cylinders 12.

[0011] The crankshaft 13 is connected to a piston (not shown) located in each cylinder 12. The space defined by the inner wall of the cylinder 12 and the piston forms a combustion chamber R. When fuel burns in each combustion chamber R, the piston located in that cylinder 12 moves. As a result, the crankshaft 13 connected to the piston rotates.

[0012] The internal combustion engine 10 also includes an intake passage 21, a throttle valve 22, a plurality of fuel injectors 23, and a plurality of ignition devices 24. The internal combustion engine 10 also includes an exhaust passage 26, a catalyst 27, and a filter 28.

[0013] The intake passage 21 is connected to the cylinders 12. A portion of the intake passage 21, including the downstream end, branches into four passages. Each branched passage is connected to one of the cylinders 12. The intake passage 21 is used to allow intake gas to flow from outside the internal combustion engine 10 into the combustion chamber R.

[0014] The throttle valve 22 is located upstream of the branched portion of the intake passage 21. The throttle valve 22 adjusts the intake gas flow rate, which is the amount of intake gas flowing through the intake passage 21.

[0015] The fuel injectors 23 are located near the downstream end of the intake passage 21. The internal combustion engine 10 is equipped with four fuel injectors 23 corresponding to the four cylinders 12. The fuel injectors 23 inject liquid fuel supplied from a fuel tank 31 (described later) into the intake passage 21. That is, the fuel injectors 23 supply fuel to the combustion chamber R via the intake passage 21. The ignition devices 24 are located in the cylinders 12. The internal combustion engine 10 is equipped with four ignition devices 24 corresponding to the four cylinders 12. The ignition devices 24 ignite the mixture of fuel and intake gas by spark discharge to combust the mixture in the combustion chamber R.

[0016] The exhaust passage 26 is connected to the cylinders 12. A portion of the exhaust passage 26, including the upstream end, branches into four. Each branched passage is connected to one of the cylinders 12. The exhaust passage 26 discharges exhaust gas from each of the cylinders 12 to the outside of the internal combustion engine 10.

[0017] The catalyst 27 is located downstream of the branched portion of the exhaust passage 26. The catalyst 27 purifies the exhaust gas flowing through the exhaust passage 26. The filter 28 is located downstream of the catalyst 27 in the exhaust passage 26. The filter 28 collects particulate matter contained in the exhaust gas flowing through the exhaust passage 26.

[0018] 2, the hybrid vehicle 100 includes a fuel supply mechanism 30. The fuel supply mechanism 30 includes a fuel tank 31, an evaporated fuel passage 32, a shutoff valve 33, and an evaporated fuel adjustment valve .

[0019] The fuel tank 31 is a tank that stores fuel to be burned in the combustion chamber R. The evaporated fuel passage 32 is a passage that allows evaporated fuel generated in the fuel tank 31 to flow together with air into the intake passage 21. The evaporated fuel passage 32 connects from the fuel tank 31 to a location in the intake passage 21 that is downstream of the throttle valve 22 and upstream of the combustion chamber R.

[0020] The shut-off valve 33 is attached midway through the evaporated fuel passage 32. The shut-off valve 33 switches the flow path of the evaporated fuel passage 32 between a fully open state and a fully closed state. The evaporated fuel adjustment valve 34 is attached to the evaporated fuel passage 32 at a location downstream of the shut-off valve 33. The evaporated fuel adjustment valve 34 adjusts the opening of the flow path of the evaporated fuel passage 32. The evaporated fuel adjustment valve 34 can continuously change its opening between a fully open state and a fully closed state. Note that the "open state" includes not only the fully open state but also all opening states at which evaporated fuel can flow through the evaporated fuel passage 32. In other words, the "open state" refers to any opening state excluding the fully closed state.

[0021] The fuel supply mechanism 30 includes a feed pump 35 and a liquid fuel passage 36 . Feed pump 35 is an electric pump that draws liquid fuel stored in fuel tank 31. Liquid fuel passage 36 connects feed pump 35 to fuel injection device 23. In other words, liquid fuel passage 36 is a passage through which liquid fuel discharged from feed pump 35 flows to fuel injection device 23.

[0022] As shown in FIG. 1, the hybrid vehicle 100 includes a first planetary gear mechanism 40, a ring gear shaft 45, a second planetary gear mechanism 50, a reduction mechanism 62, a differential mechanism 63, and a plurality of drive wheels 64.

[0023] The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to the first motor generator 71. The ring gear 42 is an internal gear and is located coaxially with the sun gear 41. Each pinion gear 43 is located between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gear 43. The pinion gear 43 is rotatable on its own axis and is capable of revolving by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 13.

[0024] The ring gear shaft 45 is connected to the ring gear 42. The ring gear shaft 45 is also connected to drive wheels 64 via a reduction mechanism 62 and a differential mechanism 63. The reduction mechanism 62 reduces the rotational speed of the ring gear shaft 45 and outputs it. The differential mechanism 63 allows a difference in rotational speed to occur between the left and right drive wheels 64.

[0025] The second planetary gear mechanism 50 includes a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gear 53. The pinion gear 53 is rotatable. The carrier 54 is fixed to the case 55. Therefore, the pinion gear 53 is unable to revolve.

[0026] The hybrid vehicle 100 includes a battery 75 , a first inverter 76 , and a second inverter 77 . The battery 75 is a secondary battery. The first inverter 76 converts AC power to DC power between the first motor generator 71 and the battery 75. The first inverter 76 also adjusts the amount of power exchanged between the first motor generator 71 and the battery 75. The second inverter 77 converts AC power to DC power between the second motor generator 72 and the battery 75. The second inverter 77 also adjusts the amount of power exchanged between the second motor generator 72 and the battery 75. The first motor generator 71 is capable of rotating the crankshaft 13 of the engine body 11 without injecting liquid fuel from the fuel injector 23. In other words, the first motor generator 71 can motor the internal combustion engine 10.

[0027] The hybrid vehicle 100 includes a catalyst temperature sensor 81 , a coolant temperature sensor 82 , an evaporated fuel concentration sensor 83 , a negative pressure sensor 84 , an accelerator operation amount sensor 85 , and a power switch 86 .

[0028] The catalyst temperature sensor 81 is attached to the exhaust passage 26 downstream of the catalyst 27. The catalyst temperature sensor 81 detects the temperature of the exhaust gas flowing out from the catalyst 27 as the catalyst temperature TC.

[0029] The coolant temperature sensor 82 detects the coolant temperature TW, which is the temperature of the coolant for cooling the engine body 11. Although not shown, the coolant temperature sensor 82 is attached to the outlet of a water jacket defined inside the engine body 11. The coolant temperature sensor 82 detects the temperature of the coolant flowing through the water jacket as the coolant temperature TW.

[0030] The fuel vapor concentration sensor 83 detects a fuel vapor concentration CF that indicates the concentration of fuel vapor in the gas filling the fuel tank 31. The fuel vapor concentration sensor 83 is attached inside the fuel tank 31.

[0031] The negative pressure sensor 84 is attached to the intake passage 21 near the connection point with the evaporated fuel passage 32. The negative pressure sensor 84 detects the negative pressure at the connection point with the evaporated fuel passage 32 in the intake passage 21 as the intake negative pressure PI. The accelerator operation amount sensor 85 detects the accelerator operation amount ACC, which is the amount of operation of the accelerator pedal operated by the driver.

[0032] When the power supply of hybrid vehicle 100 is in an off state, power switch 86 is turned on to issue a start request R1. When the power supply of hybrid vehicle 100 is in an on state, power switch 86 is turned off to issue a stop request R2. Crank angle sensor 87 is located near crankshaft 13. Crank angle sensor 87 detects the rotational phase SC of crankshaft 13.

[0033] <Control device> The hybrid vehicle 100 is equipped with a control device 90. The control device 90 controls the hybrid vehicle 100. In particular, when executing an internal combustion engine start program PS (described later), the control device 90 controls the throttle valve 22, the fuel injector 23, the ignition device 24, the shut-off valve 33, the evaporated fuel control valve 34, and the first motor generator 71. The control device 90 obtains a signal indicative of the catalyst temperature TC from a catalyst temperature sensor 81. The control device 90 obtains a signal indicative of the coolant temperature TW from a coolant temperature sensor 82. The control device 90 obtains a signal indicative of the evaporated fuel concentration CF from an evaporated fuel concentration sensor 83. The control device 90 obtains a signal indicative of the intake vacuum pressure PI from a vacuum sensor 84. The control device 90 obtains a signal indicative of the accelerator operation amount ACC from an accelerator operation amount sensor 85. The control device 90 obtains a signal indicative of a start request R1 and a signal indicative of a stop request R2 from a power switch 86. The control device 90 acquires a signal indicating the rotational phase SC of the crankshaft 13 from the crank angle sensor 87 .

[0034] The control device 90 includes a CPU 91, a peripheral circuit 92, a ROM 93, a storage device 94, and a bus 95. The bus 95 connects the CPU 91, the peripheral circuit 92, the ROM 93, and the storage device 94 so that they can communicate with one another. The peripheral circuit 92 includes a circuit that generates a clock signal that regulates internal operation, a power supply circuit, a reset circuit, etc. The ROM 93 pre-stores various programs that the CPU 91 uses to execute various controls. The CPU 91 controls the hybrid vehicle 100 by executing the various programs stored in the ROM 93. In particular, the ROM 93 stores an internal combustion engine starting program PS for starting the internal combustion engine 10. The CPU 91 executes the internal combustion engine starting program PS to control the throttle valve 22, the fuel injector 23, the ignition device 24, the shut-off valve 33, the vapor fuel control valve 34, and the first motor-generator 71 to start the internal combustion engine 10. In FIG. 2, signals used by the CPU 91 to control these devices are shown as operation signals MS1 to MS6.

[0035] <About the series of processes performed by the internal combustion engine start program> <Handling when in cold state> When a request to start the internal combustion engine 10 is made while the internal combustion engine 10 is stopped, the CPU 91 executes the internal combustion engine start program PS. For example, when the hybrid vehicle 100 is in an off state and the control device 90 acquires a signal indicating a start request R1 from the power switch 86, the CPU 91 determines that a request to start the internal combustion engine 10 has been made. Note that when the hybrid vehicle 100 is in an off state, the isolation valve 33 is in a fully closed state.

[0036] 3, when the CPU 91 starts a series of processes of the internal combustion engine start program PS, it first performs the process of step S11. In step S11, the CPU 91 determines whether the catalyst temperature TC is lower than the cold catalyst temperature TCL. The cold catalyst temperature TCL is predetermined as a value lower than the activation temperature of the catalyst 27. If the catalyst temperature TC is lower than the cold catalyst temperature TCL (S11: YES), the CPU 91 proceeds to the process of step S12.

[0037] In step S12, the CPU 91 determines whether the coolant temperature TW is lower than the cold coolant temperature TWL. The cold coolant temperature TWL is predetermined as a temperature for determining whether warming up of the internal combustion engine 10 has been completed. The cold coolant temperature TWL is, for example, several tens of degrees. If the coolant temperature TW is lower than the cold coolant temperature TWL (S12: YES), the CPU 91 proceeds to step S13. That is, in step S12, the CPU 91 performs cold determination processing for determining whether the internal combustion engine 10 has been started in a cold state. Then, if the coolant temperature TW is lower than the cold coolant temperature TWL, the CPU 91 determines that the temperature of the internal combustion engine 10 is in a cold state, that is, below a predetermined specified temperature. On the other hand, if the coolant temperature TW is equal to or higher than the cold coolant temperature TWL, the CPU 91 determines that the internal combustion engine 10 is not in a cold state. The cold coolant temperature TWL corresponds to the specified temperature.

[0038] In step S13, the CPU 91 calculates a first gas flow rate V1, which is the flow rate of gas flowing through the evaporated fuel passage 32, and a second gas flow rate V2, which is the flow rate of gas flowing through the intake passage 21, required for performing a first start process (described later). The first gas flow rate V1 is the flow rate of gas flowing through the evaporated fuel passage 32 per unit time required for providing the torque required for starting the internal combustion engine 10 solely with evaporated fuel. In other words, when gas flows through the evaporated fuel passage 32 at the first gas flow rate V1, the mass of evaporated fuel supplied to the intake passage 21 per unit time matches a required amount DA, which is the mass of fuel per unit time required for starting the internal combustion engine 10. The required amount DA is determined in advance through testing or simulation. In step S13, the CPU 91 calculates the first gas flow rate V1 based on a signal indicating the evaporated fuel concentration CF from the evaporated fuel concentration sensor 83. Specifically, the CPU 91 calculates the first gas flow rate V1 to a smaller value as the evaporated fuel concentration CF increases.

[0039] The second gas flow rate V2 is the flow rate of gas flowing through the intake passage 21 per unit time that is necessary to make the air-fuel ratio of the gas supplied to the combustion chamber R equal to the target air-fuel ratio when the flow rate of the gas flowing through the evaporated fuel passage 32 is set to the first gas flow rate V1. The target air-fuel ratio is, for example, the stoichiometric air-fuel ratio. Thereafter, the CPU 91 proceeds to step S14.

[0040] In step S14, the CPU 91 determines whether the required amount DA, which is the mass of fuel required per unit time, can be supplied using evaporated fuel alone when starting the internal combustion engine 10. The mass of evaporated fuel per unit time supplied to the intake passage 21 when the evaporated fuel control valve 34 is fully opened is defined as the maximum supply amount SAL. At this time, if the required amount DA is equal to or less than the maximum supply amount SAL, the evaporated fuel can be supplied using evaporated fuel alone.

[0041] Specifically, the CPU 91 makes this determination by comparing the first gas flow rate V1 calculated in step S13 with a maximum gas flow rate VL, which is the maximum gas flow rate per unit time that can flow through the evaporated fuel passage 32. If the first gas flow rate V1 is equal to or less than the maximum gas flow rate VL, the CPU 91 determines that the required amount DA can be supplied by evaporated fuel alone. The maximum gas flow rate VL is the maximum gas flow rate per unit time that can flow through the evaporated fuel passage 32 when the evaporated fuel regulating valve 34 is fully opened. If the first gas flow rate V1 is equal to or less than the maximum gas flow rate VL (S14: YES), the CPU 91 proceeds to step S15.

[0042] In step S15, the CPU 91 performs an intake gas flow rate adjustment process. In the intake gas flow rate adjustment process, the CPU 91 controls the throttle valve 22 to adjust the opening of the throttle valve 22 to an open state. In this step S15, the CPU 91 adjusts the opening of the throttle valve 22 so that the gas flow rate per unit time flowing through the intake passage 21 becomes the second gas flow rate V2. In other words, the CPU 91 adjusts the opening of the throttle valve 22 so that the mass of air per unit time supplied to the combustion chamber R divided by the required amount DA becomes the target air-fuel ratio. Thereafter, the CPU 91 proceeds to step S16.

[0043] In step S16, the CPU 91 starts the motoring process. In the motoring process, the CPU 91 controls the first motor generator 71 to motor the internal combustion engine 10. Specifically, the CPU 91 controls the first motor generator 71 via the first inverter 76, thereby applying torque from the first motor generator 71 to the crankshaft 13. The CPU 91 then rotates the crankshaft 13 at a predetermined speed using the torque from the first motor generator 71. This generates negative pressure in the combustion chamber R. The CPU 91 continues this motoring process after step S16. Thereafter, the CPU 91 proceeds to step S17.

[0044] In step S17, the CPU 91 determines whether a predetermined specified time ST has elapsed since the start of the motoring process. The specified time ST is determined by testing or simulation as the time required for the negative pressure in the combustion chamber R to reach a predetermined required negative pressure PN after the start of the motoring process. The required negative pressure PN is determined as a pressure that allows sufficient gas to be supplied from the evaporated fuel passage 32. If the specified time ST has not elapsed (S17), the CPU 91 repeats the process of step S17. On the other hand, if the specified time ST has elapsed (S17), the CPU 91 proceeds to step S18.

[0045] In step S18, the CPU 91 determines whether or not the intake negative pressure PI is smaller than the required negative pressure PN. If the intake negative pressure PI is smaller than the required negative pressure PN, the CPU 91 advances the process to step S19.

[0046] In step S19, the CPU 91 performs an evaporated fuel adjustment process. In the evaporated fuel adjustment process, the CPU 91 allows evaporated fuel to flow through the evaporated fuel passage 32 by adjusting the opening degree of the evaporated fuel adjustment valve 34 during the motoring process. The CPU 91 adjusts the opening degree of the evaporated fuel adjustment valve 34 so that the mass of evaporated fuel per unit time supplied to the intake passage 21 approaches the required amount DA. Specifically, the CPU 91 adjusts the opening degree of the evaporated fuel adjustment valve 34 so that the gas flow rate per unit time flowing through the evaporated fuel passage 32 becomes the first gas flow rate V1. Therefore, when step S19 is executed, the mass of evaporated fuel per unit time supplied to the intake passage 21 matches the required amount DA. The CPU 91 then proceeds to step S20.

[0047] In step S20, the CPU 91 changes the isolation valve 33 from a fully closed state to a fully open state. After that, the CPU 91 advances the process to step S21. In step S21, the CPU 91 performs a first start process. In the first start process, the CPU 91 controls the ignition device 24 to ignite during the motoring process that has been ongoing since step S16, thereby starting the internal combustion engine 10. Thereafter, the CPU 91 proceeds to step S22.

[0048] In step S22, the CPU 91 determines whether or not the internal combustion engine 10 has completed starting. Specifically, first, the CPU 91 calculates the rotational speed of the crankshaft 13 based on the rotational phase SC of the crankshaft 13. Next, the CPU 91 determines whether or not the rotational speed of the crankshaft 13 is equal to or greater than a predetermined specified rotational speed. The specified rotational speed is determined in advance through testing or simulation as the rotational speed of the crankshaft 13 at which starting of the internal combustion engine 10 is considered to have been completed. Then, if the internal combustion engine 10 has not completed starting (S22: NO), the CPU 91 returns the process to step S20. On the other hand, if the internal combustion engine 10 has completed starting (S22: YES), the CPU 91 advances the process to step S22.

[0049] In step S23, the CPU 91 ends the motoring process. Specifically, the CPU 91 stops applying torque from the first motor generator 71 to the crankshaft 13. Thereafter, the CPU 91 ends the series of processes.

[0050] <Handling when not in cold state> When a negative determination is made in step S11 or step S12 shown in Fig. 3, the CPU 91 advances the process to step S30 shown in Fig. 4. Specifically, when the catalyst temperature TC is equal to or higher than the cold catalyst temperature TCL (S11: NO), or when the coolant temperature TW is equal to or higher than the cold coolant temperature TWL, the CPU 91 advances the process to step S30. In other words, when the catalyst 27 is in an activated state, or when the internal combustion engine 10 is not in a cold state, the CPU 91 advances the process to step S30.

[0051] As shown in Fig. 4, in step S30, the CPU 91 starts the motoring process. In the motoring process, the CPU 91 controls the first motor generator 71 to motor the internal combustion engine 10. The process of step S30 is the same as the process of step S16 described above. The CPU 91 continues this motoring process after step S30. Thereafter, the CPU 91 proceeds to step S31.

[0052] In step S31, the CPU 91 performs intake gas flow rate adjustment processing. The CPU 91 controls the throttle valve 22 to adjust the opening of the throttle valve 22 to an open state. In step S31, the opening of the throttle valve 22 is adjusted so that the mass of air per unit time supplied to the combustion chamber R divided by the required amount DA becomes the target air-fuel ratio. In step S31, the gas flow rate per unit time flowing through the intake passage 21 becomes larger than the second gas flow rate V2 by the amount of air not being supplied from the evaporated fuel passage 32 to the intake passage 21. Therefore, the opening of the throttle valve 22 becomes a value that is larger than the opening of the throttle valve 22 in step S15. Thereafter, the CPU 91 proceeds to step S32.

[0053] In step S32, the CPU 91 starts driving the fuel injector 23. The CPU 91 drives the fuel injector 23 so as to supply the requested amount DA of liquid fuel to the combustion chamber R. Thereafter, the CPU 91 advances the process to step S33.

[0054] In step S33, the CPU 91 performs a second start-up process. In the second start-up process, the CPU 91 drives the fuel injector 23 to supply liquid fuel to the combustion chamber R, while controlling and igniting the ignition device 24, thereby starting the internal combustion engine 10. Thereafter, the CPU 91 advances the process to step S34.

[0055] In step S34, the CPU 91 determines whether or not the internal combustion engine 10 has completed starting. Details are the same as in step S22. If the internal combustion engine 10 has not completed starting (S34: NO), the CPU 91 returns the process to step S33. On the other hand, if the internal combustion engine 10 has completed starting (S34), the CPU 91 proceeds to step S35.

[0056] In step S35, the CPU 91 ends the motoring process. Specifically, the CPU 91 stops applying torque from the first motor generator 71 to the crankshaft 13. Thereafter, the CPU 91 ends the series of processes.

[0057] In this way, when the internal combustion engine 10 is not in a cold state, the CPU 91 starts the internal combustion engine 10 by executing the second start-up process without executing the evaporative fuel adjustment process during the motoring process and the first start-up process.

[0058] <What to do when the maximum supply amount is less than the required amount> When a negative determination is made in step S14 shown in Fig. 3, the CPU 91 advances the process to step S41 shown in Fig. 5. Specifically, when the first gas flow rate V1 is greater than the maximum gas flow rate VL (S14: NO), the CPU 91 advances the process to step S41. In other words, when the maximum supply amount SAL is smaller than the required amount DA, the CPU 91 advances the process to step S41.

[0059] 5, in step S41, the CPU 91 calculates the amount of fuel shortage SA. Specifically, the CPU 91 sets the amount of fuel shortage SA to a value obtained by subtracting the maximum supply amount SAL from the required amount DA. Thereafter, the CPU 91 advances the process to step S42.

[0060] In step S42, the CPU 91 performs an intake gas flow rate adjustment process. The CPU 91 controls the throttle valve 22 to adjust the opening of the throttle valve 22 to an open state. In step S42, the opening of the throttle valve 22 is adjusted so that the mass of air per unit time supplied to the combustion chamber R divided by the required amount DA becomes the target air-fuel ratio. Thereafter, the CPU 91 proceeds to step S43.

[0061] Steps S43 to S47 are the same as steps S16 to S20 described above. Therefore, detailed description thereof will be omitted. In step S46, the opening of the evaporated fuel control valve 34 is fully opened. Therefore, the mass of evaporated fuel per unit time supplied to the intake passage 21 is the maximum supply amount SAL. Therefore, although the mass of evaporated fuel per unit time supplied to the intake passage 21 does not match the required amount DA, it is as close to the required amount DA as possible. After step S47, the CPU 91 proceeds to step S48.

[0062] In step S48, the CPU 91 performs additional injection processing. Specifically, the CPU 91 starts driving the fuel injector 23. Then, the CPU 91 drives the fuel injector 23 so as to supply liquid fuel to the combustion chamber R per unit time by the amount of fuel shortage SA. Thereafter, the CPU 91 proceeds to step S49.

[0063] The processing in steps S49 to S51 is the same as the processing in steps S21 to S23, and therefore detailed description thereof will be omitted. After step S51, the CPU 91 ends the series of processing.

[0064] <What to do when the intake negative pressure does not reach the required negative pressure> When a negative determination is made in step S18 shown in Fig. 3 or when a negative determination is made in step S45 shown in Fig. 5, the CPU 91 proceeds to step S61 shown in Fig. 6. Specifically, when the intake negative pressure PI does not decrease to the required negative pressure PN, the CPU 91 proceeds to step S61.

[0065] 6, in step S61, the CPU 91 performs an intake gas flow rate adjustment process. The processes from step S61 to step S65 are the same as the processes from step S31 to step S35. Therefore, detailed explanations will be omitted. Then, after the process of step S65, the CPU 91 ends the series of processes.

[0066] (Operation of the embodiment) According to the above embodiment, when the CPU 91 starts the motoring process, the first motor generator 71 motors the internal combustion engine 10. This generates a negative pressure in the combustion chamber R. Then, after the specified time ST has elapsed, the intake negative pressure PI becomes smaller than the required negative pressure PN. The intake negative pressure PI causes air to flow from the evaporated fuel passage 32 into the intake passage 21 together with the evaporated fuel.

[0067] (Effects of the embodiment) (1) According to the above embodiment, the first motor generator 71 motors the internal combustion engine 10, thereby generating an intake negative pressure PI. The intake negative pressure PI allows evaporated fuel to be supplied to the combustion chamber R. Then, the amount of evaporated fuel supplied to the combustion chamber R can be controlled to an amount suitable for starting the internal combustion engine 10 by the evaporated fuel adjustment process. Therefore, when burning the evaporated fuel to start the internal combustion engine 10, it is not necessary to use a device solely for supplying evaporated fuel, such as a boost pump for feeding evaporated fuel.

[0068] (2) According to the above embodiment, the evaporative fuel adjustment process adjusts the opening of the evaporative fuel adjustment valve 34 so that the mass of evaporative fuel supplied to the intake passage 21 per unit time approaches the required amount DA. Also, the intake gas flow rate adjustment process adjusts the opening of the throttle valve 22 so that the mass of air supplied to the combustion chamber R per unit time divided by the required amount DA becomes the target air-fuel ratio. Therefore, the intake gas flow rate adjustment process and the evaporative fuel adjustment process supply air and evaporative fuel to the combustion chamber R so as to achieve the target air-fuel ratio. As a result, it is possible to prevent the air-fuel ratio from becoming extremely lean or extremely rich when the internal combustion engine 10 is started.

[0069] (3) According to the above embodiment, when the maximum supply amount SAL is less than the required amount DA, the CPU 91 performs additional injection processing. By this additional injection processing, when the evaporated fuel alone is insufficient to meet the required amount DA, liquid fuel is also supplied to the combustion chamber R. Therefore, it is possible to prevent a shortage of fuel when starting the internal combustion engine 10.

[0070] (4) According to the above embodiment, in the additional injection process, the CPU 91 drives the fuel injection device 23 to supply liquid fuel to the combustion chamber R by the amount of fuel deficiency SA per unit time. In other words, even if the evaporated fuel alone is insufficient to meet the required amount DA when starting the internal combustion engine 10, liquid fuel is added in an amount sufficient to meet the required amount DA. As a result, it is possible to supply fuel that is neither too much nor too little for the required amount DA when starting the internal combustion engine 10.

[0071] (5) When the internal combustion engine 10 is cold, heavy components of the fuel exist as liquid fuel. If the internal combustion engine 10 is started using liquid fuel at this time, there is a risk that combustion may become unstable or that harmful substances may be more likely to be emitted. In the above embodiment, when the internal combustion engine 10 is cold, the internal combustion engine 10 is started using evaporated fuel. Therefore, the internal combustion engine 10 can be started using evaporated fuel with fewer heavy components.

[0072] On the other hand, when the internal combustion engine 10 is not in a cold state, heavy components of the fuel are unlikely to exist as liquid fuel, which reduces the possibility of unstable combustion or the increased emission of harmful substances. According to the above embodiment, when the internal combustion engine 10 is not in a cold state, the CPU 91 executes the second start process without executing the evaporated fuel adjustment process during the motoring process and the first start process. In other words, when the internal combustion engine 10 is not in a cold state, the internal combustion engine 10 is started without using evaporated fuel. In this case, liquid fuel is supplied both before and after the start of the internal combustion engine 10. Therefore, fuel can be supplied without significantly changing the properties of the fuel before and after the start of the internal combustion engine 10 is completed.

[0073] (Other embodiments) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0074] In the internal combustion engine 10, the fuel injection device 23 may be a device that directly injects liquid fuel into the combustion chamber R, or a device that injects liquid fuel into the intake passage 21 and supplies the injected liquid fuel to the combustion chamber R together with the intake gas.

[0075] The fuel supply mechanism 30 does not necessarily have to include the shutoff valve 33. It is sufficient that the flow rate of the gas flowing through the evaporated fuel passage 32 can be adjusted by adjusting the opening of the evaporated fuel adjustment valve 34.

[0076] The fuel supply mechanism 30 may further include a vaporization accelerator. The vaporization accelerator is located inside the fuel tank 31 and accelerates the vaporization of the liquid fuel inside the fuel tank 31. For example, the vaporization accelerator may be a device that accelerates the vaporization of the liquid fuel by using ultrasound.

[0077] The fuel tank 31 may have a vaporization chamber for storing evaporated fuel in addition to a storage chamber for storing liquid fuel. If the fuel tank 31 only has a storage chamber, filling the entire storage chamber with liquid fuel would leave no space for evaporated fuel to exist. In this regard, by not storing liquid fuel in the vaporization chamber, a reasonable amount of evaporated fuel can remain in the fuel tank 31.

[0078] In the fuel supply mechanism 30, the evaporated fuel passage 32 may be branched in accordance with the number of combustion chambers R. In this example, each branched evaporated fuel passage 32 may be connected to each branched intake passage 21. Furthermore, in this modified example, an open / close valve may be provided in each branched evaporated fuel passage 32. This allows evaporated fuel to be supplied to each combustion chamber R at the appropriate timing.

[0079] The control device 90 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 90 may also be configured as a circuit including one or more dedicated hardware circuits, such as an application-specific integrated circuit (ASIC), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0080] The control device 90 may acquire the evaporated fuel concentration CF without relying on the evaporated fuel concentration sensor 83. For example, it is assumed that the storage device 94 stores in advance the vapor pressure characteristics of the liquid fuel stored in the fuel tank 31, and the hybrid vehicle 100 has a tank temperature sensor that detects the temperature inside the fuel tank 31. In this case, the CPU 91 may acquire the evaporated fuel concentration CF by calculating it based on the vapor pressure characteristics of the liquid fuel and the temperature inside the fuel tank 31. Also, it is assumed that the hybrid vehicle 100 has a pressure sensor that detects the pressure inside the fuel tank 31 and an oxygen concentration sensor that detects the oxygen concentration inside the fuel tank 31. In this case, it is assumed that the CPU 91 may detect the evaporated fuel concentration CF by calculating it based on the pressure inside the fuel tank 31 and the oxygen concentration inside the fuel tank 31.

[0081] The CPU 91 may start the internal combustion engine start program PS when a request to start the internal combustion engine 10 is made while the hybrid vehicle 100 is running on the first motor generator 71 and the second motor generator 72. In this case, if the accelerator operation amount ACC is detected to be large, the first gas flow rate V1 is likely to be calculated to be large. Therefore, in such a case, it is easy to obtain a significant effect of performing processing when the maximum supply amount SAL is smaller than the first gas flow rate V1.

[0082] In the evaporated fuel adjustment process in step S19, the CPU 91 does not have to adjust the opening degree of the evaporated fuel adjustment valve 34 so that it matches the required amount DA. In the evaporated fuel adjustment process, the CPU 91 may adjust the opening degree of the evaporated fuel adjustment valve 34 so that it approaches the required amount DA through the process of step S19, even if it does not necessarily match the required amount DA. Furthermore, in the evaporated fuel adjustment process, the CPU 91 may adjust the opening degree of the evaporated fuel adjustment valve 34 regardless of the required amount DA. For example, in the evaporated fuel adjustment process, the CPU 91 may adjust the opening degree of the evaporated fuel adjustment valve 34 to a predetermined fixed opening degree that is suitable for starting the internal combustion engine 10.

[0083] In the intake gas flow rate adjustment process in step S15, the CPU 91 may adjust the opening of the throttle valve 22 regardless of the required amount DA. For example, in the intake gas flow rate adjustment process, the CPU 91 may adjust the opening of the throttle valve 22 to a predetermined fixed opening suitable for starting the internal combustion engine 10.

[0084] In the additional injection process, the CPU 91 does not need to supply liquid fuel from the fuel injector 23 by the amount of fuel deficiency SA. When the maximum supply amount SAL is less than the required amount DA, supplying even a small amount of liquid fuel from the fuel injector 23 can reduce the extent of the fuel deficiency.

[0085] Furthermore, the fuel injection device 23 has a minimum fuel injection amount that can ensure an accurate fuel injection amount. When the minimum injection amount is the minimum amount of fuel that the fuel injection device 23 can supply per combustion cycle, the value obtained by adding the amount that can be supplied per unit time at the minimum injection amount to the maximum supply amount SAL may exceed the required amount DA. In this case, in the additional injection process, the CPU 91 may supply liquid fuel to the combustion chamber R at the minimum injection amount. In the intake gas adjustment process, the CPU 91 may adjust the opening of the throttle valve 22 so that the mass of evaporated fuel supplied to the intake passage 21 per unit time becomes the required amount DA minus the amount that can be supplied per unit time at the minimum injection amount. In this way, the total amount of liquid fuel and evaporated fuel supplied to the combustion chamber R becomes the required amount DA. Therefore, even when liquid fuel is supplied to the combustion chamber R by the additional injection process, it can be burned at the target air-fuel ratio.

[0086] The CPU 91 may not perform the additional injection process when the maximum supply amount SAL is less than the required amount DA. In this case, the CPU 91 may start the internal combustion engine 10 using only liquid fuel without using evaporated fuel when the maximum supply amount SAL is less than the required amount DA. In other words, the CPU 91 may perform the second start process when the maximum supply amount SAL is less than the required amount DA.

[0087] In the above embodiment, the CPU 91 may perform the first start process regardless of the result of the cold state determination process. Also, the CPU 91 may not necessarily perform the cold state determination process. The system of the hybrid vehicle 100 is not limited to the example of the above embodiment, as long as the motor generator can rotate the crankshaft 13 to motor the internal combustion engine 10 . [Explanation of symbols]

[0088] 10...Internal combustion engine 11...Engine body 12...cylinder 13...Crankshaft 21...Intake passage 22...Throttle valve 23…Fuel injection device 24...Ignition device 26...Exhaust passage 27...Catalyst 28...Filter 30…Fuel supply mechanism 31...Fuel tank 32...Fuel vapor passage 33...Shut-off valve 34...Fuel vapor control valve 35...Feed pump 36…Liquid fuel passage 71...First motor generator 72...Second motor generator 90...Control device 91...CPU 100...Hybrid vehicle

Claims

1. an internal combustion engine serving as a drive source, the internal combustion engine having an engine body having a combustion chamber, a fuel injection device that supplies liquid fuel to the combustion chamber, an ignition device that ignites liquid fuel for combustion in the combustion chamber, an intake passage that is connected to the combustion chamber and that flows intake gas into the combustion chamber, and a throttle valve that is provided in the intake passage and that adjusts the intake gas flow rate, which is the flow rate of the intake gas; an evaporated fuel passage that connects a fuel tank to a portion of the intake passage that is downstream of the throttle valve and upstream of the combustion chamber, and that allows evaporated fuel generated in the fuel tank to flow into the intake passage together with air; an evaporated fuel regulating valve provided in the evaporated fuel passage for regulating an opening degree of the evaporated fuel passage; a motor generator capable of motoring to rotate the crankshaft of the internal combustion engine without injecting the liquid fuel from the fuel injection device; a control device that controls the start of the internal combustion engine by controlling the ignition device, the throttle valve, the vapor fuel control valve, and the motor generator; A hybrid vehicle comprising: The control device an intake gas flow rate adjustment process for controlling the throttle valve to an open state; a motoring process for controlling the motor generator to motor the internal combustion engine; and when a predetermined time has elapsed since the start of the motoring process, a process is executed to determine whether or not an intake negative pressure, which is a negative pressure in the evaporated fuel passage, is smaller than a necessary negative pressure, which is a pressure that allows gas to be supplied from the evaporated fuel passage; In the process of determining whether the intake negative pressure is smaller than the required negative pressure, when it is determined that the intake negative pressure is smaller than the required negative pressure, the control device an evaporated fuel adjustment process for allowing the evaporated fuel to flow through the evaporated fuel passage by adjusting an opening degree of the evaporated fuel adjustment valve during the motoring process; a first start process for starting the internal combustion engine by controlling the ignition device to ignite during the motoring process; In the process of determining whether the intake negative pressure is smaller than the required negative pressure, when it is determined that the intake negative pressure is equal to or greater than the required negative pressure, the control device does not execute the evaporated fuel adjustment process during the motoring process and the first start process, but executes a second start process in which the fuel injection device is driven to supply the liquid fuel to the combustion chamber while controlling the ignition device to ignite the liquid fuel and start the internal combustion engine. Hybrid vehicle.

2. In the vapor fuel adjustment process, an opening degree of the vapor fuel adjustment valve is adjusted so that a mass of the vapor fuel supplied to the intake passage per unit time approaches a required amount, which is a mass of fuel per unit time required for starting the internal combustion engine, In the intake gas flow rate adjustment process, the opening of the throttle valve is adjusted so that the mass of air supplied to the combustion chamber divided by the required amount becomes a target air-fuel ratio. The hybrid vehicle according to claim 1 .

3. When the mass of the evaporated fuel per unit time supplied to the intake passage when the opening degree of the evaporated fuel control valve is fully opened is set to a maximum supply amount, the maximum supply amount is less than the required amount, The control device executes an additional injection process for driving the fuel injection device to supply the fuel to the combustion chamber in addition to the evaporated fuel adjustment process. The hybrid vehicle according to claim 2 .

4. In the additional injection process, the amount obtained by subtracting the maximum supply amount from the requested amount is supplied from the fuel injection device per unit time. The hybrid vehicle according to claim 3 .

5. When the minimum fuel injection amount per combustion cycle that can be supplied by the fuel injection device is defined as the minimum injection amount, If the value obtained by adding the amount that can be supplied per unit time at the minimum injection amount to the maximum supply amount exceeds the required amount, the additional injection process supplies the fuel to the combustion chamber at the minimum injection amount, and the evaporated fuel adjustment process adjusts the opening of the throttle valve so that the mass of the evaporated fuel per unit time supplied to the intake passage becomes a value obtained by subtracting the amount that can be supplied per unit time at the minimum injection amount from the required amount. The hybrid vehicle according to claim 3 .

6. The control device further executes a cold state determination process for determining whether the temperature of the internal combustion engine is below a predetermined specified temperature, When it is determined in the cold state determination process that the internal combustion engine is in the cold state, the control device executes the motoring process, the evaporated fuel adjustment process during the motoring process, and the first starting process, When it is determined in the cold state determination process that the internal combustion engine is not in the cold state, the control device executes the second start-up process without executing the evaporated fuel adjustment process during the motoring process and the first start-up process. The hybrid vehicle according to any one of claims 1 to 5.

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