Hybrid vehicles

Abstract

To synchronize an engine speed with a motor rotating speed more rapidly even when the motor rotating speed suddenly increases in starting an engine during intermittent stopping.SOLUTION: A hybrid vehicle includes: an engine with a cylinder injection valve; a motor; a clutch connected to a crankshaft of the engine, and the motor; an automatic gear connected to a rotary shaft and a driving shaft of the motor; and a control device for controlling these parts. When a predetermined rotating speed increase state in which a motor rotating speed increases to a predetermined rotating speed or higher, is estimated in starting the engine, the control device sets a throttle opening to be larger compared to when the predetermined rotating speed increase state is not estimated.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a hybrid vehicle, and more particularly to a hybrid vehicle equipped with an engine, a motor, a clutch connected to the engine crankshaft and the motor, and an automatic transmission connected to a rotating shaft of the motor and a drive shaft to which drive wheels are connected. [Background technology]

[0002] A conventional hybrid vehicle of this type includes an engine, a motor connected to the engine's output shaft via a clutch, and an automatic transmission connected to a drive shaft to which the motor's rotating shaft is coupled (see, for example, Patent Document 1). In this hybrid vehicle, when starting the engine while the vehicle is running on the motor, the engine speed is increased by slipping the clutch until the engine is able to rotate independently. The clutch engagement force is temporarily reduced, and the engine speed is synchronized with the motor speed before the clutch is fully engaged. When synchronizing the engine speed with the motor speed, the higher the motor speed, the earlier the throttle opening is increased and the intake valve opening / closing timing is advanced. This increases engine torque earlier, shortening the time required to synchronize the engine speed with the motor speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-058259 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hybrid vehicle described above, when the driver depresses the accelerator pedal heavily, it may take time for the engine speed to synchronize with the motor speed. When the accelerator pedal is depressed heavily, the automatic transmission downshifts, causing the motor speed to increase rapidly. In this case, the difference between the engine speed and the motor speed increases rapidly, and the engine speed cannot increase in time, so it takes time to synchronize with the motor speed.

[0005] The hybrid vehicle of the present invention is a hybrid vehicle equipped with an engine, a motor connected to the engine output shaft via a clutch, and an automatic transmission connected to the motor's rotating shaft and a drive shaft to which the drive wheels are connected.The main object of the hybrid vehicle of the present invention is to more quickly synchronize the engine rotation speed with the motor rotation speed even when the motor rotation speed increases sharply when starting the engine after it has been intermittently stopped. [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; a clutch connected to a crankshaft of the engine and the motor; an automatic transmission connected to a rotary shaft of the motor and a drive shaft to which drive wheels are coupled; and a control device that controls the engine, the motor, the clutch, and the automatic transmission, The control device half-engages the clutch and starts fuel injection and ignition while increasing the engine speed by the motor, with the engine in a stopped state due to a fuel cut or in a state of a speed lower than the motor speed, and then controls the engine, the motor, and the clutch so as to synchronize the engine speed with the motor speed, and when a predetermined rotation speed increase state in which the motor rotation speed increases to or exceeds the predetermined rotation speed is estimated at the time of a predetermined engine start, the control device sets the throttle opening to be larger than when the predetermined rotation speed increase state is not estimated. It is characterized by:

[0008] The hybrid vehicle of the present invention includes an engine having an in-cylinder injection valve, a motor, a clutch connected to the engine crankshaft and the motor, an automatic transmission connected to a drive shaft to which the motor's rotating shaft is coupled, and a control device that controls the engine, motor, clutch, and automatic transmission. The control device performs a predetermined engine start by partially engaging the clutch and initiating fuel injection and ignition while increasing the engine speed using the motor, with the engine stopped due to a fuel cut or at a speed lower than that of the motor. The control device then controls the engine, motor, and clutch to synchronize the engine speed with the motor speed. During this predetermined engine start, when a predetermined rotation speed increase state is estimated in which the motor rotation speed increases above the predetermined rotation speed, the control device sets the throttle opening larger than when the predetermined rotation speed increase state is not estimated. As a result, when the predetermined rotation speed increase state is estimated, the control device quickly increases engine torque to increase the engine rotation speed, thereby quickly synchronizing the engine rotation speed with the motor rotation speed.

[0009] In the hybrid vehicle of the present invention, even if the predetermined engine speed increase state is estimated during the predetermined engine start, the control device may set the throttle opening in the same manner as when the predetermined engine speed increase state is not estimated until a predetermined time has elapsed since the start of fuel injection and ignition to the engine. That is, the control device increases the throttle opening after a predetermined time has elapsed since the start of fuel injection and ignition to the engine. This reduces the amount of air supplied to a purification device that purifies engine exhaust, thereby preventing the purification catalyst of the purification device from becoming lean and preventing emissions from deteriorating.

[0010] In the hybrid vehicle of the present invention, the control device may be configured to estimate the specified rotation speed increase state when, at the time of the specified engine start, the accelerator opening is equal to or greater than a specified opening and a downshift of the automatic transmission is estimated.

[0011] In the hybrid vehicle of the present invention, the control device may set the throttle opening using a first throttle opening setting map that defines a first relationship between the motor rotation speed and the throttle opening when the predetermined rotation speed increase state is not estimated, and set the throttle opening using a second throttle opening setting map that defines a second relationship between the motor rotation speed and the throttle opening that results in a larger throttle opening than the first relationship when the predetermined rotation speed increase state is estimated. This allows the throttle opening to be set quickly. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to 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] 4 is a flowchart showing an example of a start-up process executed by the engine ECU 24 and the HVECU 70. [Figure 4]4 is a flowchart showing an example of a throttle opening setting map selection process executed by an engine ECU 24. [Figure 5] FIG. 10 is an explanatory diagram showing an example of a normal map and a high rotation map for throttle setting. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0014] Fig. 1 is a schematic diagram showing the configuration of a hybrid vehicle 20 equipped with an engine device according to one embodiment of the present invention. Fig. 2 is a schematic diagram showing the configuration of an engine 22 equipped in 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, a hydraulic control device 36, 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.

[0015] 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.

[0016] 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). As is well known, crank position sensor 140 is composed of a timing rotor with 34 protrusions, formed by removing two consecutive protrusions as missing teeth from the 36 protrusions spaced every 10 degrees on its outer periphery, and an electromagnetic pickup that detects the passage of the protrusions as the timing rotor rotates.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The clutch K0 is configured as, for example, a hydraulically driven friction clutch, and is driven by a hydraulic control device 36 to connect and disconnect the crankshaft 23 of the engine 22 and the rotary shaft 31 of the motor 30. The hydraulic control device 36 has a hydraulic circuit 37 to the clutch K0, and adjusts the hydraulic pressure of the hydraulic circuit 37 to place the clutch K0 in a half-engaged state (slip-engaged state), a fully engaged state, or a released state (disengaged state). The hydraulic control device 36 is controlled by the HVECU 70.

[0023] 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 forms forward gears from first to sixth 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. A hydraulic control device (not shown) regulates the hydraulic pressure of hydraulic oil from a mechanical oil pump or an electric oil pump and supplies it to the clutch K0 and the automatic transmission 45. 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. The hydraulic control device 36 that drives the clutch K0 and the hydraulic control device that drives the automatic transmission 40 may be integrated or separate.

[0024] 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.

[0025] 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.

[0026] 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. Examples of signals output from the HVECU 70 include a control signal to the hydraulic control device 36 that drives the clutch K0, a control signal to the hydraulic control device that drives the automatic transmission 40, 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.

[0027] 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.

[0028] 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*.

[0029] 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*.

[0030] 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*.

[0031] In this embodiment, the engine device corresponds to the engine 22, the clutch K0, the hydraulic control device 36, the motor 30, the HVECU 70, the engine ECU 24, and the motor ECU 34.

[0032] Next, the operation of the hybrid vehicle 20 of this embodiment configured as described above will be described, particularly the start of the engine 22 when the engine 22 is operating intermittently. The start of the intermittently stopped engine 22 can be considered as starting the engine 22 when it is completely stopped, or as starting the engine 22 while the engine speed Ne of the engine 22 is decreasing due to a fuel cut to intermittently stop the engine 22. Figure 3 is a flowchart showing an example of a start-up process executed by the engine ECU 24 and the HVECU 70 when starting the intermittently stopped engine 22.

[0033] When the startup process is executed, the clutch K0 is first partially engaged (slip engaged) to output the target cranking torque Tcr* from the motor 30, thereby starting cranking of the engine 22 (step S100). This process is performed by transmitting a control signal from the HVECU 70 to a hydraulic control device (not shown) so that the clutch K0 is partially engaged (slip engaged), and transmitting the sum of the required torque Tin* required of the input shaft 41 and the target cranking torque Tcr* to the motor ECU 34 as a torque command Tm* for the motor 30. Upon receiving the control signal, the hydraulic control device adjusts the hydraulic pressure to a predetermined level so that the clutch K0 can transmit the target cranking torque Tcr* while slipping. Upon receiving the torque command Tm*, the motor ECU 34 controls the switching of a switching element (not shown) of the inverter 32 so that the torque command Tm* is output from the motor 30. When starting the engine 22 that is completely stopped, the target cranking torque Tcr* is set to a torque sufficient to move a cylinder stopped in the compression stroke past compression top dead center, and is set based on the stop crank angle θstop and the elapsed time since the engine 22 was stopped. The reason for using the stop crank angle θstop is to take into account the pressure inside the cylinder stopped in the compression stroke, and the reason for using the elapsed time since the engine 22 was stopped is to take into account the decrease in pressure inside the cylinder stopped in the compression stroke over time. On the other hand, when starting the engine 22 whose rotation speed has been reduced by a fuel cut, the target cranking torque Tcr* is set to a torque sufficient to increase the rotation speed Ne of the engine 22, and is determined based on the rotation speed Ne of the engine 22, etc.

[0034] Simultaneously with cranking of the engine 22, start-up control of fuel injection and throttle / ignition is initiated (step S110). The start-up control of fuel injection may, for example, be a control that sets a fuel injection amount and fuel injection timing during the compression stroke that will result in good explosive combustion for the expected amount of air in the cylinder from the first explosive combustion (initial explosion) to a first predetermined number of explosive combustions (e.g., 10, 12, 15, etc.), and a control that sets a fuel injection amount and fuel injection timing during the intake stroke and compression stroke that will result in good explosive combustion for the expected amount of air in the cylinder for a second predetermined number of subsequent explosive combustions (e.g., 10, 12, 15, etc.). The start-up control of the throttle may, for example, be a control that sets a throttle opening based on the rotation speed Ne of the engine 22 and the rotation speed Nmg of the motor 30 so that the rotation speed Ne of the engine 22 approaches the rotation speed Nmg of the motor 30. An example of ignition start-up control is to set a retarded ignition timing for the initial explosive combustion (initial explosion) to suppress shock, and then to set the ignition timing based on the rotation speed Ne of the engine 22 and the rotation speed Nmg of the motor 30 so that the rotation speed Ne of the engine 22 approaches the rotation speed Nmg of the motor 30.

[0035] Next, the hydraulic control device waits until the conditions for releasing the clutch K0 are met (step S120), and then releases the clutch K0 by controlling the hydraulic control device to wait at a hydraulic pressure that does not cause the clutch K0 to slip (step S130). Examples of conditions for releasing the clutch K0 include a condition that the compression top dead center has been passed a predetermined number of times (for example, two or three times), a condition that the rotation speed Ne of the engine 22 is increasing, and a condition that the rotation speed Ne of the engine 22 is equal to or greater than a threshold value based on the rotation speed Nmg of the motor 30. In this embodiment, it is determined that the conditions for releasing the clutch K0 are met when all of the above three conditions are met.

[0036] When the clutch K0 is released, the process waits for the conditions for engaging the clutch K0 to be met (step S140), then the clutch K0 is fully engaged (step S150), and this process ends. The conditions for engaging the clutch K0 include, for example, that the differential rotation speed ΔN between the rotation speed Ne of the engine 22 and the rotation speed Nmg of the motor 30 is less than a threshold value (e.g., 50 rpm, 100 rpm, 150 rpm, etc.) and that the number of ignitions is equal to or greater than a predetermined number (e.g., 5, 6, 8, etc.). As for the start-up control of fuel injection and throttle ignition while the clutch K0 is released, as described above, the throttle opening and ignition timing are controlled based on the rotation speed Ne of the engine 22 and the rotation speed Nmg of the motor 30 so that the rotation speed Ne of the engine 22 approaches the rotation speed Nmg of the motor 30.

[0037] While this startup control is being executed, the engine ECU 24 repeatedly performs a throttle opening setting map selection process, as shown in FIG. 4. When the throttle opening setting map selection process is executed, it is determined whether it is possible to predict that the rotation speed Nmg of the motor 30 will rapidly increase to or exceed a predetermined rotation speed Nup (e.g., 1600 rpm or 2000 rpm) (step S200). This determination can be made, for example, based on whether the accelerator pedal 83 is depressed deeply enough to cause the accelerator opening Acc to rapidly increase to or exceed a predetermined accelerator opening Aref (e.g., 85% or 90%). When the accelerator pedal 83 is depressed deeply, the HVECU 70 changes the target gear M* of the automatic transmission 45 to a lower gear along the shift line map in order to achieve rapid acceleration, and downshifts the gear M of the automatic transmission 45 to the target gear M*. At this time, the rotation speed Nmg of the motor 30 rapidly increases due to the downshift. In step S200, it is determined whether a sudden increase in the rotation speed Nmg of the motor 30 due to the downshift is predicted.

[0038] If it is determined in step S100 that it is not possible to predict that the rotation speed Nmg of the motor 30 will rapidly increase to or exceed the predetermined rotation speed Nup, the normal map A is set as the throttle opening setting map (step S120), and this process ends. Figure 5 shows examples of the normal map A and the high rotation speed map B. As shown in Figure 5, the normal map A sets a larger throttle opening TH as the rotation speed Nmg of the motor 30 increases.

[0039] If it is determined in step S100 that the rotation speed Nmg of the motor 30 can be predicted to rapidly increase to or exceed the predetermined rotation speed Nup, it is determined whether a predetermined time has elapsed since the start request (step S110). If it is determined that the predetermined time has not elapsed since the start request, normal map A is set as the throttle opening setting map (step S120), and the process ends. Here, the predetermined time can be, for example, 100 msec or 150 msec. The reason for using normal map A as the throttle opening setting map until the predetermined time has elapsed since the start request is to ensure the initial explosive combustion (initial explosion) and reduce the shock of the final explosion. On the other hand, if it is determined that the predetermined time has elapsed since the start request, high rotation map B, which has a throttle opening TH greater than that of normal map A, is set as the throttle opening setting map (step S130), and the process ends. 5, the higher the rotation speed Nmg of the motor 30, the larger the throttle opening TH set in the high rotation speed map B compared to the normal operation map A. By using the high rotation speed map B as the throttle opening setting map in this way, a larger throttle opening TH is set compared to when the normal operation map A is used as the throttle opening setting map. Therefore, the rotation speed Ne of the engine 22 can be increased quickly in response to a sudden increase in the rotation speed Nmg of the motor 30, so that the rotation speed Ne of the engine 22 can be made closer to the rotation speed Nmg of the motor 30.

[0040] In the hybrid vehicle 20 of the embodiment described above, the clutch K0 is partially engaged (slip engaged) to output the target cranking torque Tcr* from the motor 30 to start cranking of the engine 22, and startup control of fuel injection, throttle, and ignition is initiated to start the engine 22. The clutch K0 is then released by waiting for a condition for disengaging the clutch K0 to be satisfied, with the hydraulic pressure controlled to prevent slippage of the clutch K0. The clutch K0 is then fully engaged when a condition for engaging the clutch K0 is satisfied, such as when the differential rotation speed ΔN between the rotation speed Ne of the engine 22 and the rotation speed Nmg of the motor 30 is less than a threshold value. During such engine 22 start, if it is predicted that the rotation speed Nmg of the motor 30 will rapidly increase to or exceed a predetermined rotation speed Nup, the high rotation speed map B, which sets the throttle opening TH larger than the normal rotation speed map A, is used as the throttle opening setting map after a predetermined time has elapsed since the start request. As a result, compared to when the normal map A is used as the throttle opening setting map, the engine speed Ne can be increased more quickly in response to a sudden increase in the motor speed Nmg, so that the engine speed Ne can be brought closer to the motor speed Nmg. Since the normal map A is used as the throttle opening setting map to set the throttle opening TH until a predetermined time has elapsed since the start request, the initial explosive combustion (initial explosion) can be more reliably performed and the shock of the final explosion can be reduced.

[0041] In the hybrid vehicle 20 of the embodiment, when it is predicted that the rotation speed Nmg of the motor 30 will rapidly increase to or exceed a predetermined rotation speed Nup, the throttle opening TH is set using the high rotation speed map B, in which the throttle opening TH is larger than the normal time map A, as the throttle opening setting map after waiting for a predetermined time to elapse from the start request. However, when it is predicted that the rotation speed Nmg of the motor 30 will rapidly increase to or exceed the predetermined rotation speed Nup, the throttle opening TH may also be set using the high rotation speed map B, in which the throttle opening TH is larger than the normal time map A, as the throttle opening setting map without waiting for a predetermined time to elapse from the start request.

[0042] In the hybrid vehicle 20 of the embodiment, whether or not it is possible to predict that the rotation speed Nmg of the motor 30 will suddenly increase to or exceed the predetermined rotation speed Nup is determined by determining whether or not the accelerator pedal 83 is depressed deeply and the accelerator opening Acc suddenly increases to or exceeds the predetermined accelerator opening Aref. However, other methods may be used instead of or in addition to determining the sudden increase in the accelerator opening Acc.

[0043] In the hybrid vehicle 20 of the embodiment, when starting the engine 22 that has been intermittently stopped, the clutch K0 is partially engaged (slip engaged) to crank the engine 22 to start the engine 22, and then the clutch K0 is released to bring the rotation speed Ne of the engine 22 closer to the rotation speed Nmg of the motor 30, and the clutch K0 is fully engaged when the rotation speed Ne of the engine 22 approximately matches the rotation speed Nmg of the motor 30. However, it is also possible to keep the clutch K0 partially engaged (slip engaged) even after the engine 22 has started to bring the rotation speed Ne of the engine 22 closer to the rotation speed Nmg of the motor 30, and to fully engage the clutch K0 when the rotation speed Ne of the engine 22 approximately matches the rotation speed Nmg of the motor 30.

[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 motor 30 corresponds to the "motor," the clutch K0 corresponds to the "clutch," 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

[Claim 1] A hybrid vehicle comprising: an engine having an in-cylinder injection valve; a motor; a clutch connected to a crankshaft of the engine and the motor; an automatic transmission connected to a rotary shaft of the motor and a drive shaft to which drive wheels are coupled; and a control device that controls the engine, the motor, the clutch, and the automatic transmission, The control device half-engages the clutch and starts fuel injection and ignition while increasing the engine speed by the motor, with the engine in a stopped state due to a fuel cut or in a state of a speed lower than the motor speed, and then controls the engine, the motor, and the clutch so as to synchronize the engine speed with the motor speed, and when a predetermined engine start is performed and a predetermined rotation speed increase state in which the motor rotation speed increases to or exceeds the predetermined rotation speed due to a downshift of the automatic transmission, the control device sets the throttle opening to be larger than when the predetermined rotation speed increase state is not estimated. A hybrid vehicle characterized by

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