Hybrid vehicles

Abstract

To enable an engine to start rapidly, even when failing to start the engine by starting-control by which the engine is started while performing fuel injection and ignition processing to a cylinder that reaches a compression top dead center first.SOLUTION: In starting an engine intermittently stopped, a hybrid vehicle, when using one of a plurality of starting-control which include first starting control of starting the engine by performing fuel injection and ignition processing to a cylinder which reaches a compression top dead center first and second starting control of starting the engine by starting the fuel injection and the ignition processing when the engine is cranked by a motor and a rotation speed of the engine nearly matches a rotation speed of the motor, requests for execution of the second starting control, when starting the engine by the first starting control, and executes starting of the engine by the second starting control immediately when failing to start the engine by the first starting control.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a hybrid vehicle, and more particularly to a hybrid vehicle equipped with an engine having a direct injection valve and a motor connected to the output shaft of the engine via a clutch. [Background technology]

[0002] A conventional hybrid vehicle of this type is equipped with an engine, a motor connected to the engine's output shaft via a clutch, and an automatic transmission connected to the motor's rotating shaft and axles (see, for example, Patent Document 1). In this hybrid vehicle, when starting the engine that has been intermittently stopped, the engine is started using a first starting method in which combustion in the engine is started with the clutch not fully engaged when the motor's rotation speed exceeds a threshold, and using a second starting method in which combustion in the engine is started with the clutch fully engaged when the motor's rotation speed is equal to or lower than the threshold. This allows for smooth switching between driving modes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-152337 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hybrid vehicle described above, one possible method for quickly starting the engine after it has been intermittently stopped is to inject fuel and ignite the cylinder that reaches the compression top dead center first. However, with this starting method, slight discrepancies in the stopping position of the cylinder that reaches the compression top dead center first, the amount of fuel injected, or the ignition timing can sometimes prevent the engine from starting properly, making it impossible to quickly respond to the driver's torque request.

[0005] The main object of the hybrid vehicle of the present invention is to quickly start the engine even when an attempt to start the engine by start control, which starts the engine by injecting fuel and igniting into the cylinder that first reaches compression top dead center, fails. [Means for solving the problem]

[0006] The hybrid vehicle of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The hybrid vehicle of the present invention is A hybrid vehicle comprising: an engine having an in-cylinder injection valve; a motor connected to an output shaft of the engine via a clutch; an automatic transmission having an input shaft and an output shaft connected to a rotary shaft of the motor and a drive shaft to which drive wheels are connected; and a control device that controls the engine, the motor, the clutch, and the automatic transmission, When starting the engine that has been intermittently stopped, the control device uses one of a plurality of start controls including a first start control that controls the engine, the motor, and the clutch to start the engine by partially engaging the clutch to crank the engine using the motor and by injecting fuel and igniting into a cylinder that first reaches top dead center of compression in the engine, and a second start control that controls the engine, the motor, and the clutch to partially engage the clutch to crank the engine using the motor and by starting fuel injection and ignition when the engine speed substantially matches the motor speed, When starting the engine by the first start control, a request is made to execute the second start control, and when starting the engine by the first start control fails, the start of the engine is immediately executed by the second start control. It is characterized by:

[0008] A hybrid vehicle of the present invention includes an engine having an in-cylinder injection valve, a motor connected to an output shaft of the engine via a clutch, an automatic transmission having an input shaft and an output shaft connected to a drive shaft to which the rotating shaft of the motor and drive wheels are connected, and a control device that controls the engine, motor, clutch, and automatic transmission. When starting an intermittently stopped engine, the control device uses one of a plurality of start controls, including a first start control that partially engages the clutch to crank the engine using the motor and controls the engine, motor, and clutch to start the engine by injecting fuel and igniting into the cylinder that first reaches top dead center of compression in the engine, and a second start control that partially engages the clutch to crank the engine using the motor and controls the engine, motor, and clutch to start the engine by injecting fuel and igniting when the engine speed approximately matches that of the motor. When starting the engine using the first start control, the control device requests execution of the second start control, and if starting the engine using the first start control fails, immediately executes the second start control. As a result, even if the engine fails to be started by the first start control, which starts the engine by injecting fuel and igniting it into the cylinder that first reaches the compression top dead center, the second start control can be immediately executed to start the engine quickly.

[0009] In the hybrid vehicle of the present invention, the control device may be configured to start the engine by explosive combustion using stratified charge combustion if the engine coolant temperature is below a predetermined temperature when starting the engine using the second start control. This allows the engine to be started more reliably and quickly even if the engine coolant temperature is below the predetermined temperature.

[0010] In the hybrid vehicle of the present invention, the control device may be configured to advance the ignition timing earlier when the driver requests torque for driving when starting the engine through the second start control than when the driver does not request the torque. This allows the control device to quickly respond to the driver's request for torque for driving. In this case, the control device may be configured to switch the fuel injection amount from the fuel injection amount at start to the normal fuel injection amount after a delay from the start of advancing the ignition timing when the driver requests torque for driving when starting the engine through the second start control. This allows for both early torque output and combustion stability. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the outline of the configuration of an engine 22. [Figure 3] 6 is a flowchart showing an example of processing when starting the engine 22 by the first start control. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0013] Fig. 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to one embodiment of the present invention. Fig. 2 is a diagram showing an outline of the configuration of an engine 22 mounted on the hybrid vehicle 20. As shown in Fig. 1, the hybrid vehicle 20 of the embodiment includes the engine 22, a motor 30, an inverter 32, a clutch K0, an automatic transmission 40, a high-voltage battery 60, a low-voltage battery 62, a DC / DC converter 64, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0014] The engine 22 is configured as a six-cylinder internal combustion engine that uses fuel such as gasoline or diesel and outputs power through four strokes: intake, compression, expansion (explosive combustion), and exhaust. As shown in FIG. 2, the engine 22 has a port injection valve 126 that injects fuel into an intake port and an in-cylinder injection valve 127 that injects fuel into a cylinder. By having the port injection valve 126 and the in-cylinder injection valve 127, the engine 22 can operate in any of a port injection mode, an in-cylinder injection mode, and a combined injection mode. In the port injection mode, air purified by an air cleaner 122 is drawn into an intake pipe 123 and passes through a throttle valve 124 and a surge tank 125, and fuel is injected from a port injection valve 126 downstream of the surge tank 125 in the intake pipe 123 to mix the air and fuel. This air-fuel mixture is then drawn into combustion chamber 129 via intake valve 128, where it is explosively combusted by an electric spark from spark plug 130. The reciprocating motion of piston 132, which is pushed down in the cylinder bore by the energy of the mixture, is converted into rotational motion of crankshaft 23. In in-cylinder injection mode, air is drawn into combustion chamber 129 as in port injection mode, and fuel is injected from in-cylinder injection valve 127 during the intake stroke or compression stroke, where it is explosively combusted by an electric spark from spark plug 130, thereby generating rotational motion of crankshaft 23. In dual injection mode, fuel is injected from port injection valve 126 when air is drawn into combustion chamber 129, and fuel is also injected from in-cylinder injection valve 127 during the intake stroke or compression stroke, where it is explosively combusted by an electric spark from spark plug 130, thereby generating rotational motion of crankshaft 23. These injection modes are switched based on the operating state of engine 22. Exhaust gas discharged from combustion chamber 129 into exhaust pipe 134 via exhaust valve 133 is then discharged into the outside air via purification device 135 and PM filter 136. Purification device 135 has a purification catalyst (three-way catalyst) 135a that purifies harmful components in the exhaust gas, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). PM filter 136 is formed as a porous filter using ceramics, stainless steel, or the like, and captures particulate matter (PM) such as soot in the exhaust gas.It should be noted that instead of the PM filter 136, a four-way catalyst may be used that combines the purification function of a three-way catalyst with the function of trapping particulate matter.

[0015] The operation of the engine 22 is controlled by an engine ECU 24. Although not shown, the engine ECU 24 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors required for controlling the operation of the engine 22 are input to the engine ECU 24 via input ports. Examples of signals input to the engine ECU 24 include a crank angle θcr from a crank position sensor 140 that detects the rotational position of a crankshaft 23 of the engine 22, and a coolant temperature Tw from a water temperature sensor 142 that detects the temperature of the coolant for the engine 22. Other examples of signals include cam angles θci and θco from a cam position sensor 144 that detects the rotational position of an intake camshaft that opens and closes intake valves 128 and an exhaust camshaft that opens and closes exhaust valves 133. Other examples include a throttle opening TH from a throttle valve position sensor 124a that detects the position of the throttle valve 124, an intake air amount Qa from an air flow meter 123a attached upstream of the throttle valve 124 in the intake pipe 123, an intake air temperature Ta from a temperature sensor 123t attached upstream of the throttle valve 124 in the intake pipe 123, and a surge pressure Ps from a pressure sensor 125a attached to the surge tank 125. Other examples include a front air-fuel ratio AF1 from a front air-fuel ratio sensor 137 attached upstream of the purification device 135 in the exhaust pipe 134, a rear air-fuel ratio AF2 from a rear air-fuel ratio sensor 138 attached between the purification device 135 and the PM filter 136 in the exhaust pipe 134, and a differential pressure ΔP from a differential pressure sensor 136a that detects a differential pressure before and after the PM filter 136 (a differential pressure between the upstream side and the downstream side).

[0016] The engine ECU 24 outputs various control signals via an output port to control the operation of the engine 22. Examples of signals output from the engine ECU 24 include a control signal to a throttle valve 124, a control signal to a port injection valve 126, a control signal to an in-cylinder injection valve 127, and a control signal to an ignition plug 130.

[0017] The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the engine 22 from the crank position sensor 140. The engine ECU 24 also calculates a load factor KL (the ratio of the volume of air actually taken in per cycle to the stroke volume per cycle of the engine 22) based on the intake air amount Qa from the air flow meter 123a and the rotation speed Ne of the engine 22. The engine ECU 24 also calculates a PM accumulation amount Qpm as the accumulation amount of particulate matter accumulated on the PM filter 136 based on the differential pressure ΔP from the differential pressure sensor 136a, and calculates a filter temperature Tf as the temperature of the PM filter 136 based on the rotation speed Ne of the engine 22 and the load factor KL.

[0018] 1, a starter motor 25 for cranking the engine 22 and an alternator 26 for generating electricity using power from the engine 22 are connected to the crankshaft 23 of the engine 22. The starter motor 25 and the alternator 26 are connected to a low-voltage power line 63 together with a low-voltage battery 62, and are controlled by the HVECU 70.

[0019] The motor 30 is configured as a synchronous generator motor and has a rotor with a permanent magnet embedded in the rotor core and a stator with a three-phase coil wound around the stator core. A rotating shaft 31 to which the rotor of the motor 30 is fixed is connected to the crankshaft 23 of the engine 22 via a clutch K0 and to an input shaft 41 of an automatic transmission 45. The inverter 32 is used to drive the motor 30 and is connected to a high-voltage power line 61. The motor 30 is rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 34 controlling the switching of multiple switching elements of the inverter 32.

[0020] The motor ECU 34 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors are input to the motor ECU 34 via the input port. Examples of signals input to the motor ECU 34 include a rotational position θm from a rotational position sensor 30a that detects the rotational position of the rotor (rotating shaft 31) of the motor 30, and phase currents Iu and Iv from current sensors that detect the phase currents of each phase of the motor 30. The motor ECU 34 outputs control signals to the inverter 32 via the output port. The motor ECU 34 is connected to the HVECU 70 via the communication port. The motor ECU 34 calculates the rotational speed Nm of the motor 30 based on the rotational position θm of the rotor (rotating shaft 31) of the motor 30 from the rotational position sensor 30a.

[0021] The clutch K0 is configured as, for example, a hydraulically driven friction clutch, and is controlled by the HVECU 70 to connect and disconnect the crankshaft 23 of the engine 22 and the rotary shaft 31 of the motor 30.

[0022] The automatic transmission 40 includes a torque converter 43 and, for example, a six-speed automatic transmission 45. The torque converter 43 is configured as a typical fluid power transmission device and amplifies the torque of the power of an input shaft 41 connected to the rotating shaft 31 of the motor 30 and transmits it to a transmission input shaft 44, which is the input shaft of the automatic transmission 45, or transmits the torque directly without amplifying it. The automatic transmission 45 includes the transmission input shaft 44, an output shaft 42 connected to drive wheels 49 via a differential gear 48, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches, brakes). Each of the multiple friction engagement elements has a hydraulic servo configured with a piston, multiple friction engagement plates (friction plates and separator plates), an oil chamber to which hydraulic oil is supplied, etc. The automatic transmission 45 establishes forward gears from first to sixth gears and reverse gears by engaging and disengaging multiple friction engagement elements, and transmits power between the transmission input shaft 44 and the output shaft 42. The clutch K0 and the automatic transmission 45 are supplied with hydraulic oil from a mechanical oil pump or an electric oil pump at a regulated pressure by a hydraulic control device (not shown). The hydraulic control device includes a valve body with multiple oil passages, multiple regulator valves, multiple linear solenoid valves, and the like. This hydraulic control device is controlled by the HVECU 70.

[0023] High-voltage battery 60 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery with a rated voltage of several hundred volts, and is connected to high-voltage power line 61 together with inverter 32. Low-voltage battery 62 is configured as, for example, a lead-acid battery with a rated voltage of about 12 V or 14 V, and is connected to low-voltage power line 63 together with starter motor 25 and alternator 26. DC / DC converter 64 is connected to high-voltage power line 61 and low-voltage power line 63. DC / DC converter 64 supplies power from high-voltage power line 61 to low-voltage power line 63 while stepping down the voltage.

[0024] The HVECU 70 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors are input to the HVECU 70 via the input ports. Examples of signals input to the HVECU 70 include the rotation speed Nin from a rotation speed sensor 41a attached to the input shaft 41 of the automatic transmission 40, the rotation speed Nmi from a rotation speed sensor 44a attached to the transmission input shaft 44 of the automatic transmission 40, and the rotation speed Nout from a rotation speed sensor 42a attached to the output shaft 42 of the automatic transmission 40. Other examples of signals input to the HVECU 70 include the voltage Vbh of the high-voltage battery 60 from a voltage sensor attached between the terminals of the high-voltage battery 60, the current Ibh of the high-voltage battery 60 from a current sensor attached to the output terminal of the high-voltage battery 60, and the voltage Vbl from a voltage sensor attached between the terminals of the low-voltage battery 62. Other examples include an ignition signal from an ignition switch 80, a shift position SP from a shift position sensor 82 that detects the operating position of a shift lever 81, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 87.

[0025] Various control signals are output from the HVECU 70 via an output port. Examples of signals output from the HVECU 70 include a control signal to the starter motor 25 and a control signal to the alternator 26. Other examples include control signals to the clutch K0 and the automatic transmission 40 (hydraulic control device), and a control signal to the DC / DC converter 64. The HVECU 70 is connected to the engine ECU 24 and the motor ECU 34 via communication ports. The HVECU 70 calculates the rotation speed ratio Gt of the automatic transmission 40 by dividing the rotation speed Nin of the input shaft 41 of the automatic transmission 40 from the rotation speed sensor 41a by the rotation speed Nout of the output shaft 42 of the automatic transmission 40 from the rotation speed sensor 42a.

[0026] In the hybrid vehicle 20 of this embodiment configured as described above, the engine 22, the clutch K0, the motor 30, and the automatic transmission 40 are controlled by cooperative control between the HVECU 70, the engine ECU 24, and the motor ECU 34 to travel in a hybrid driving mode (HV driving mode) or an electric driving mode (EV driving mode). Here, the HV driving mode is a mode in which the clutch K0 is engaged and the vehicle travels using the power of the engine 22, and the EV driving mode is a mode in which the clutch K0 is disengaged and the vehicle travels without using the power of the engine 22.

[0027] In controlling the automatic transmission 40 in the HV driving mode or the EV driving mode, the HVECU 70 first sets a target gear position M* of the automatic transmission 45 based on the accelerator opening Acc and the vehicle speed V. Then, when the gear position M of the automatic transmission 45 matches the target gear position M*, the HVECU 70 controls the automatic transmission 45 so that the gear position M is maintained. On the other hand, when the gear position M and the target gear position M* differ, the HVECU 70 controls the automatic transmission 45 so that the gear position M matches the target gear position M*.

[0028] In controlling the engine 22 and motor 30 in the HV driving mode, the HVECU 70 first sets a required torque Tout* required for driving (required from the output shaft 42 of the automatic transmission 40) based on the accelerator opening Acc and the vehicle speed V. Next, the HVECU 70 sets a value obtained by dividing the required torque Tout* of the output shaft 42 by the rotation speed ratio Gt of the automatic transmission 40 as the required torque Tin* of the input shaft 41. After setting the required torque Tin* of the input shaft 41 in this manner, the HVECU 70 sets a target torque Te* of the engine 22 and a torque command Tm* of the motor 30 so that the required torque Tin* is output to the input shaft 41, and transmits the target torque Te* of the engine 22 to the engine ECU 24 and the torque command Tm* of the motor 30 to the motor ECU 34. Upon receiving the target torque Te*, the engine ECU 24 performs operation control of the engine 22 (intake air amount control, fuel injection control, ignition control, etc.) so that the engine 22 operates at the target torque Te*. When the motor ECU 34 receives the torque command Tm*, it controls the switching of the multiple switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*.

[0029] In controlling the motor 30 in the EV driving mode, the HVECU 70 sets the required torque Tin* of the input shaft 41 in the same manner as in the HV driving mode, sets a torque command Tm* for the motor 30 so that the required torque Tin* is output to the input shaft 41, and transmits the torque command Tm* to the motor ECU 34. Upon receiving the torque command Tm*, the motor ECU 34 performs switching control of the multiple switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*.

[0030] Next, the operation of the hybrid vehicle 20 of this embodiment configured as described above will be described, particularly the operation when starting the intermittently stopped engine 22. The intermittently stopped engine 22 can be started using a plurality of start controls, including a first start control in which the clutch K0 is partially engaged (slip engaged) and the motor 30 outputs a target cranking torque Tcr* to crank the engine 22 and perform initial fuel injection and ignition (initial combustion) in the cylinder that first reaches top dead center (TDC) of compression stroke, and a second start control in which the clutch K0 is partially engaged (slip engaged) and the motor 30 outputs a target cranking torque Tcr* to crank the engine 22 and perform fuel injection and ignition (initial combustion) when the rotation speed Ne of the engine 22 approximately matches the rotation speed Nmg of the motor 30. Starting the engine 22 using the first start control is often selected from the viewpoint of rapid engine 22 start.

[0031] In the first start control, in order to start the cylinder that first reaches top dead center of compression, the throttle valve 124 is temporarily opened immediately before stopping the engine 22 and is stopped within a predetermined crank angle range. The throttle valve 124 is temporarily opened immediately before stopping the engine 22 in order to increase the amount of air in the cylinder that stops during the compression stroke. The fuel injection amount Fi is set based on the time Tstop elapsed since the engine 22 was stopped, the stop crank angle θstop (position of the piston 132), and the intake manifold pressure (intake manifold pressure) Pin at the timing when the intake valve 128 is closed. In this embodiment, the relationships between the time Tstop elapsed since the engine 22 was stopped, the stop crank angle θstop (position of the piston 132), the intake manifold pressure Pin, and the fuel injection amount Fi are determined in advance through experiments, analysis, machine learning, or the like and stored as a map for setting the fuel injection amount for initial combustion. When the elapsed time Tstop, the stop crank angle θstop, and the intake manifold pressure Pin are given, the corresponding fuel injection amount Fi is derived from the map. The ignition timing Ti is set based on the stop crank angle θstop, the target crank torque Tcr*, and the rotation speed Nmg of the motor 30. In this embodiment, the relationships between the stop crank angle θstop, the target crank torque Tcr*, the rotation speed Nmg of the motor 30, and the ignition timing Ti are determined in advance by experiment, analysis, machine learning, or the like, and stored as a map for setting the ignition timing for initial combustion. When the stop crank angle θstop, the target crank torque Tcr*, and the rotation speed Nmg of the motor 30 are given, the corresponding ignition timing Ti is derived from the map. Note that a predetermined opening (for example, 5%) is basically used as the throttle opening TH when the engine 22 is started.

[0032] In the second start-up control, the fuel injection amount Fi is set based on the rotation speed Ne of the engine 22 or the rotation speed Nmg of the motor 30. The ignition timing Ti is set to a predetermined retarded ignition timing (for example, a timing retarded from the compression top dead center) in order to suppress the shock of the initial combustion.

[0033] Next, an operation when an attempt to start the intermittently stopped engine 22 under the first start control fails will be described. Fig. 3 is a flowchart showing an example of a process when starting the engine 22 under the first start control.

[0034] 3, a request is first made to start the engine 22 using the second start control (step S100). This request is made so that if starting the engine 22 using the first start control fails, the engine 22 will be started using the second start control immediately.

[0035] Next, it is determined whether the engine 22 coolant temperature Tw detected by the temperature sensor 142 is less than a threshold value Tref (step S110). The threshold value Tref can be, for example, 60°C or 70°C. If it is determined that the engine 22 coolant temperature Tw is less than the threshold value Tref, the explosive combustion in each cylinder of the engine 22 is set to stratified combustion (step S120). This is because stratified combustion improves startability when the engine 22 coolant temperature Tw is low. Note that if it is determined that the engine 22 coolant temperature Tw is less than the threshold value Tref, the explosive combustion in each cylinder of the engine 22 is set to normal combustion. Normal combustion refers to combustion that is either homogeneous combustion or stratified combustion depending on the state of the engine 22, the driver's request, etc.

[0036] Next, starting of the engine 22 by the first start control is initiated (step S130), and it is determined whether starting of the engine 22 by the first start control was successful or unsuccessful (step S140). This determination can be made based on whether initial combustion by fuel injection and ignition was performed successfully in the cylinder that first reaches compression top dead center. If initial combustion does not occur, if the engine 22 speed Ne stalls, or if the engine 22 rotates in reverse, it can be determined that starting of the engine 22 by the first start control was unsuccessful.

[0037] If it is determined in step S140 that the start of the engine 22 under the first start control has not failed (is successful), the request for the second start control is canceled (step S150), and the start of the engine 22 under the first start control is continued (step S160). In the first start control, if initial combustion is performed successfully, and thereafter, when conditions for releasing the clutch K0 are met, such as the number of times the compression top dead center has been passed is a predetermined number or more (for example, two or three times), the engine speed Ne of the engine 22 is increasing, or the engine speed Ne is equal to or greater than a threshold based on the motor speed Nmg, the clutch K0 is placed in constant pressure standby mode, waiting with a hydraulic pressure sufficient to prevent slippage, and the fuel injection amount and ignition timing are controlled so that the engine speed Ne of the engine 22 approaches the motor speed Nmg. When it is confirmed that the rotation speed Ne of the engine 22 substantially matches the rotation speed Nmg of the motor 30 (step S170), the clutch K0 is fully engaged (step S180), the fuel injection amount and ignition timing are changed to normal (step S190), and this process ends. The normal fuel injection amount is calculated by applying various corrections to the basic fuel injection amount based on the intake air amount. The normal ignition timing is calculated according to the operating state of the engine 22.

[0038] If it is determined in step S140 that starting of the engine 22 using the first start control has failed, execution of the second start control is initiated (step S200). When execution of the second start control is initiated, fuel injection and ignition are stopped, and cranking of the engine 22 by the motor 30 is continued until the engine 22 rotation speed Ne substantially matches the motor 30 rotation speed Nmg. Once it is confirmed that the engine 22 rotation speed Ne substantially matches the motor 30 rotation speed Nmg (step S210), the clutch K0 is fully engaged (step S220). Then, it is determined whether or not there is a torque request from the driver (step S230). The presence or absence of a torque request from the driver can be determined, for example, by whether the accelerator pedal 83 is depressed by a threshold value (e.g., 5% or 7%) or more. If it is determined that there is no torque request from the driver, ignition is performed a predetermined number of times at a predetermined retarded ignition timing, and thereafter the ignition timing is advanced toward the normal ignition timing (step S240). On the other hand, if it is determined that the driver has requested torque, the ignition timing is retarded by a predetermined amount only the first time, and is advanced to the normal ignition timing from the second time onwards (step S250). This allows for a rapid response to the driver's torque request. The ignition timing is advanced by gradually advancing the ignition timing by a predetermined angle (1, 2, 3, etc.) for each ignition. After confirming that explosive combustion has occurred a predetermined number of times (e.g., 10 or 12 times) (step S260), the fuel injection amount is changed to normal (step S270), and this process ends. The reason for changing the fuel injection amount to normal after a predetermined number of explosive combustions has occurred even when the driver has requested torque is to stabilize combustion in each cylinder.

[0039] In the hybrid vehicle 20 of the embodiment described above, when starting the engine 22 by the first start control, starting of the engine 22 by the second start control is requested, and if starting of the engine 22 by the first start control fails, execution of starting of the engine 22 by the second start control is immediately initiated. This allows the engine 22 to be started quickly even if starting of the engine 22 by the first start control fails. Of course, if starting of the engine 22 by the first start control is successful, starting of the engine 22 continues by the first start control.

[0040] In the hybrid vehicle 20 of the embodiment, when the coolant temperature Tw of the engine 22 is lower than the threshold value Tref, the engine 22 is started by stratified charge combustion. This allows the engine 22 to have good startability even when the coolant temperature Tw of the engine 22 is low.

[0041] In the hybrid vehicle 20 of the embodiment, when starting the engine 22 using the second start control after a failed attempt to start the engine 22 using the first start control fails and there is a driver's torque request, the engine 22 is ignited at a predetermined retarded ignition timing only the first time, and from the second time onwards, the ignition timing is advanced toward the normal ignition timing, thereby advancing the ignition timing earlier than when there is no driver's torque request. This allows for a quick response to the driver's torque request. Moreover, even when there is a driver's torque request, the fuel injection amount is changed to that based on the normal calculation after a predetermined number of explosive combustions, thereby stabilizing explosive combustion in each cylinder of the engine 22. As a result, early torque output and stable combustion can be achieved at the same time.

[0042] In the hybrid vehicle 20 of the embodiment, when the cooling water temperature Tw of the engine 22 is lower than the threshold value Tref, the engine 22 is started by stratified combustion, but the engine 22 may also be started by normal combustion even when the cooling water temperature Tw of the engine 22 is lower than the threshold value Tref.

[0043] In the hybrid vehicle 20 of the embodiment, when starting the engine 22 by the first start control fails and the engine 22 is started by the second start control, if there is a torque request from the driver, the ignition timing is advanced earlier than when there is no torque request from the driver. However, even when there is a torque request from the driver when starting the engine 22 by the second start control, the ignition timing may be advanced in the same way as when there is no torque request from the driver.

[0044] The hybrid vehicle 20 of the embodiment is equipped with a six-speed automatic transmission 45. However, it may be equipped with a four-speed, five-speed, eight-speed, or other automatic transmission.

[0045] The hybrid vehicle 20 of the embodiment is equipped with the engine ECU 24, the motor ECU 34, and the HVECU 70. However, at least two of these may be configured as an integrated unit.

[0046] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the engine 22 corresponds to the "engine", the clutch K0 corresponds to the "clutch", the motor 30 corresponds to the "motor", the automatic transmission 40 corresponds to the "automatic transmission", and the HVECU 70, the engine ECU 24, and the motor ECU 34 correspond to the "controller".

[0047] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0048] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0049] The present invention can be used in the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0050] 20 Hybrid vehicle, 22 Engine, 23 Crankshaft, 24 Engine ECU, 25 Starter motor, 26 Alternator, 30 Motor, 30a Rotational position sensor, 31 Rotating shaft, 32 Inverter, 34 Motor ECU, 40 Automatic transmission, 41 Input shaft, 41a Speed ​​sensor, 42 Output shaft, 42a Speed ​​sensor, 43 Torque converter, 44 Transmission input shaft, 44a Speed ​​sensor, 45 Automatic transmission, 48 Differential gear, 49 Drive wheels, 60 High-voltage battery, 61 High-voltage power line, 62 Low-voltage battery, 63 Low-voltage power line, 64 DC / DC converter, 70 HVECU, 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 Brake pedal position sensor, 87 Vehicle speed sensor, 122 Air cleaner, 123 Intake pipe, 123a Air flow meter, 123t Temperature sensor, 124 Throttle valve, 124a Throttle valve position sensor, 125 Surge tank, 125a pressure sensor, 126 port injection valve, 127 in-cylinder injection valve, 128 intake valve, 129 combustion chamber, 130 spark plug, 132 piston, 133 Exhaust valve, 134 exhaust pipe, 135 purification device, 135a purification catalyst, 136 PM filter, 136a differential pressure sensor, 137 front air-fuel ratio sensor, 138 rear air-fuel ratio sensor, 140 crank position sensor, 142 water temperature sensor, 144 cam position sensor, K0 clutch.

Claims

1. A hybrid vehicle comprising: an engine having an in-cylinder injection valve; a motor connected to an output shaft of the engine via a clutch; an automatic transmission having an input shaft and an output shaft connected to a rotary shaft of the motor and a drive shaft to which drive wheels are connected; and a control device that controls the engine, the motor, the clutch, and the automatic transmission, When starting the engine that has been intermittently stopped, the control device uses one of a plurality of start controls, including a first start control that controls the engine, the motor, and the clutch to start the engine by partially engaging the clutch to crank the engine using the motor and by injecting fuel and igniting into a cylinder that first reaches top dead center of compression in the engine, and a second start control that controls the engine, the motor, and the clutch to crank the engine using the motor by partially engaging the clutch and by starting fuel injection and ignition when the engine speed substantially matches the motor speed, When starting the engine by the first start control, a request is made to execute the second start control, and when starting the engine by the first start control fails, fuel injection and ignition in the first start control are stopped and cranking of the engine by the motor is continued, thereby executing starting of the engine by the second start control. A hybrid vehicle characterized by

2. A hybrid vehicle according to claim 1, When a driver requests torque for driving when starting the engine by the second start control, the control device advances the ignition timing earlier from the starting ignition timing than when the driver does not request the torque. Hybrid car.

3. A hybrid vehicle according to claim 2, when a driver requests torque for driving when starting the engine by the second start control, the control device switches the fuel injection amount from the fuel injection amount at start to the fuel injection amount at normal time with a delay after the start of the advance of the ignition timing. Hybrid car.

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