WO2014167725A1

WO2014167725A1 - Control device of vehicle

Info

Publication number: WO2014167725A1
Application number: PCT/JP2013/061111
Authority: WO
Inventors: 小島　進
Original assignee: トヨタ自動車株式会社
Priority date: 2013-04-12
Filing date: 2013-04-12
Publication date: 2014-10-16

Abstract

The present invention improves engine startability when an engine is started up by ignition startup. A cylinder in an expansion stroke is recompressed by negative rotation of an engine (14) caused by reverse-rotation startup, and high explosion torque can be achieved during the initial explosion of the cylinder. Combustion is caused in the cylinder containing a large amount of combustion gas of the reverse-rotation startup after the initial explosion of the cylinder in the expansion stroke, and the explosion torque during the cylinder combustion is therefore reduced. Therefore, the explosion torque of the second or third explosion is suppressed, thereby lessening the increase in engine speed (Ne), minimizing the occurrence of overshooting, and ensuring that a clutch (K0) is fully engaged quickly.

Description

Vehicle control device

The present invention relates to a vehicle control apparatus including a clutch provided in a power transmission path between an engine and an electric motor.

2. Description of the Related Art A vehicle including an engine, an electric motor, and a clutch that is provided in a power transmission path between the engine and the electric motor and can disconnect the engine from driving wheels is well known. In such a vehicle, the engine is stopped with the clutch released. Various methods for starting the engine from such a state have been proposed. For example, in Patent Document 1, in the vehicle as described above, when the engine is requested to start, slip control of the clutch is performed, so that the output torque of the electric motor (if not specifically distinguished, power and force are agreed) A technique for cranking an engine and starting the engine is disclosed. Further, in Patent Document 1, when starting a direct injection engine, fuel is injected into the cylinder of the engine stopped in the expansion stroke and ignited, so that the engine rotation speed is increased by the explosion torque and the engine is started. A so-called ignition start technique has also been proposed.

Special table 2009-527411 Japanese Patent Laid-Open No. 2004-28046

By the way, it is well known that in engine start by slip control of the clutch, when the engine speed is synchronized with the motor speed, the clutch is completely engaged and the engine is shifted to engine running. On the other hand, depending on the position of the cylinder that is stopped in the expansion stroke, there is a possibility that sufficient explosion torque cannot be obtained to overcome the engine friction torque and increase the engine rotation speed. There is. Further, in the engine start by the ignition start, the engine rotation speed is increased by the engine explosion torque. Therefore, the engine rotation speed is likely to increase sharply compared to the engine start by the clutch slip control. Therefore, when an overshoot occurs in which the engine rotation speed exceeds the motor rotation speed, the complete engagement of the clutch may be delayed, and the transition to engine running may be delayed. For example, even when the engine start by the slip control of the clutch and the engine start by the ignition start are executed in combination, there is a possibility that the shift to the engine running is delayed similarly. The above-described problem is not known, and a high explosion torque is obtained at the time of the first explosion of the cylinder in the expansion stroke, and it has not yet been proposed to quickly shift to engine running.

The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a vehicle control device capable of improving engine startability when starting an engine by ignition start. .

The subject matter of the first invention for achieving the above object is: (a) Control of a vehicle including a soot engine, an electric motor, and a clutch provided in a power transmission path between the engine and the electric motor. (B) に際して When starting the engine, after burning the cylinder of the engine stopped in the compression stroke and negatively rotating the engine, the cylinder of the engine in the expansion stroke is burned. The reverse rotation start is performed to rotate the engine forward.

In this way, the cylinder in the expansion stroke is compressed again due to the negative rotation of the engine due to the reverse rotation start, and a high explosion torque can be obtained at the first explosion of the cylinder. Further, after the initial explosion of the cylinder in the expansion stroke, the cylinder containing a large amount of combustion gas in the reverse rotation start is burned, so the explosion torque at the time of combustion of the cylinder is reduced. Therefore, by suppressing the explosion torque of the second or third explosion, the increase in engine rotation speed is relaxed, the occurrence of overshoot is suppressed, and the clutch is quickly fully engaged. Therefore, the engine startability can be improved when the engine is started by the ignition start.

Here, the second invention is the vehicle control apparatus according to the first invention, wherein the reverse rotation start is performed when any cylinder of the engine is stopped in a predetermined region sandwiching a top dead center. Is to do. In this way, if any cylinder of the engine is stopped in a predetermined region across the top dead center, even if the engine cylinder stopped in the expansion stroke is burned, the engine friction torque is increased. Whereas it may be difficult to obtain a sufficient explosion torque to overcome, engine startability can be improved by performing reverse start.

According to a third aspect of the present invention, in the vehicle control device according to the first or second aspect of the invention, the fuel is injected into the cylinder of the engine in the expansion stroke when the engine is negatively rotated. There is to do in between. In this way, the fuel injection is performed in a state where air flow is generated in the cylinder due to the negative rotation, thereby promoting the homogenization of the air-fuel mixture in the cylinder in the expansion stroke. Therefore, the initial explosion of the cylinder in the expansion stroke is likely to occur, and a high explosion torque is easily obtained at the initial explosion, so that the engine startability can be improved.

According to a fourth aspect of the present invention, in the vehicle control device according to any one of the first to third aspects of the present invention, the ignition of the cylinder of the engine in the expansion stroke is a negative rotation of the engine. There is to do when the speed is slowing down. If it does in this way, it will burn with the air compression of the cylinder in an expansion stroke advanced. In addition, the first explosion of the cylinder in the expansion stroke is generated in a state where the reaction torque accompanying the negative rotation of the engine is small. Therefore, the first explosion itself of the cylinder in the expansion stroke is likely to occur, and a high explosion torque is easily obtained at the first explosion, so that the engine startability can be further improved.

According to a fifth aspect of the present invention, in the vehicle control device according to any one of the first to fourth aspects, the ignition of the cylinder of the engine in the expansion stroke is in the expansion stroke. This is to be done before the engine cylinder reaches top dead center. If it does in this way, reverse rotation start is performed appropriately and an engine startability can be improved.

According to a sixth aspect of the present invention, in the vehicle control device according to any one of the first to fifth aspects, a valve timing changing mechanism for changing a valve opening timing of the intake valve of the engine. The combustion of the cylinders of the engine stopped in the compression stroke is performed in a state where the valve opening timing of the intake valve is advanced by the valve timing changing mechanism. In this way, it is possible to burn the cylinder that is stopped in the compression stroke while the intake valve is securely closed.

According to a seventh aspect of the present invention, in the vehicle control device according to any one of the first to sixth aspects, when the engine rotates forward during the reverse rotation start, the clutch is directed to engagement. And controlling the speed of the engine to increase. If it does in this way, the output torque of the motor at the time of controlling a clutch toward engagement will be suppressed by performing reverse rotation start first. Therefore, when the motor is running, the output torque of the electric motor secured for starting the engine is suppressed, and the motor running area is expanded. In addition, since the occurrence of overshoot is suppressed by performing reverse rotation start, the clutch is quickly fully engaged. Therefore, the engine startability can be improved when the engine is started by the ignition start.

It is a figure explaining the schematic structure of the power transmission device with which the present invention was equipped, and the principal part of the control system in vehicles. It is a figure explaining the schematic structure of the engine of FIG. 1, and is a figure explaining the principal part of the control system in an engine among the control systems in a vehicle. It is a figure for demonstrating each valve opening time of an intake valve and an exhaust valve. It is a functional block diagram explaining the principal part of the control function of an electronic controller. It is a figure for demonstrating the ignition start at the time of TDC stop. It is a flowchart explaining the control operation | movement for improving the engine startability at the time of the engine start by the ignition control start, ie, the main part of the control operation of an electronic controller.

In the present invention, preferably, when any one of the cylinders of the engine is stopped in a predetermined region sandwiching the top dead center, when the engine is started, the engine is first stopped in the expansion stroke. This is a case where any cylinder of the engine is stopped in a region where even if the cylinder of the engine is burned, an explosion torque that can exceed the friction torque of the engine cannot be generated. In this way, the engine startability can be improved by performing the reverse rotation when any cylinder of the engine is stopped in a predetermined region across the top dead center.

Also preferably, the vehicle includes a transmission that forms part of a power transmission path between the electric motor and the drive wheels. The transmission includes a manual transmission such as a known synchronous mesh type parallel twin-shaft transmission having a plurality of pairs of transmission gears that are always meshed between two shafts, various automatic transmissions (planetary gear automatic transmission, synchronous mesh). Type parallel two-shaft automatic transmission, DCT, CVT, etc.). This automatic transmission is constituted by an automatic transmission alone, an automatic transmission having a fluid transmission, or an automatic transmission having a sub-transmission.

Preferably, the engine is an internal combustion engine such as a gasoline engine that generates power by burning fuel. The clutch is a wet or dry engagement device that can disconnect the engine from the drive wheel.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating a schematic configuration of a power transmission device 12 provided in a vehicle 10 to which the present invention is applied, and a diagram illustrating a main part of a control system for various controls in the vehicle 10. . 2 is a diagram for explaining a schematic configuration of the engine 14 of FIG. 1 in particular, and a diagram for explaining a main part of a control system for output control and the like in the engine 14 among the control systems in the vehicle 10. It is.

In FIG. 1, a vehicle 10 is a hybrid vehicle including an engine 14 that functions as a driving force source for traveling and an electric motor MG. The power transmission device 12 includes an engine connecting / disconnecting clutch K0 (hereinafter referred to as a clutch K0), a torque converter 16, an automatic transmission 18 and the like in order from the engine 14 side in a transmission case 20 as a non-rotating member. ing. The power transmission device 12 is connected to a propeller shaft 26 connected to a transmission output shaft 24 that is an output rotating member of the automatic transmission 18, a differential gear 28 connected to the propeller shaft 26, and the differential gear 28. And a pair of axles 30 and the like. The pump impeller 16a of the torque converter 16 is connected to the engine connecting shaft 32 via the clutch K0 and is directly connected to the electric motor MG. The turbine impeller 16 b of the torque converter 16 is directly connected to a transmission input shaft 34 that is an input rotation member of the automatic transmission 18. The pump impeller 16a is rotationally driven by the engine 14 (and / or the electric motor MG) to generate hydraulic pressure for executing the shift control of the automatic transmission 18, the engagement release control of the clutch K0, and the like. A mechanical oil pump 22 is connected. The power transmission device 12 configured in this way is suitably used for, for example, the FR type vehicle 10. In the power transmission device 12, the power of the engine 14 (the torque and the force are synonymous unless otherwise distinguished) is applied between the crankshaft 36 (see FIG. 2) of the engine 14 and the clutch K0 when the clutch K0 is engaged. It is transmitted from the engine connecting shaft 32 to be connected to the pair of driving wheels 38 via the clutch K0, the torque converter 16, the automatic transmission 18, the propeller shaft 26, the differential gear 28, the pair of axles 30, and the like in order. Thus, the power transmission device 12 constitutes a power transmission path from the engine 14 to the drive wheel 38.

The automatic transmission 18 constitutes a part of the power transmission path between the engine 14 and the electric motor MG and the drive wheels 38, and the power from the driving power source for driving (the engine 14 and the electric motor MG) is directed to the drive wheels 38. A transmission for transmission. The automatic transmission 18 is, for example, a known planetary gear type multi-stage transmission in which a plurality of shift stages having different gear ratios γ (= transmission input rotation speed Nin / transmission output rotation speed Nout) are selectively established, or a shift A known continuously variable transmission or the like in which the ratio γ is continuously changed continuously.

The electric motor MG is a so-called motor generator having a function as a motor that generates mechanical power from electric energy and a function as a generator that generates electric energy from mechanical energy. The electric motor MG generates driving power using electric energy supplied from the power storage device 44 via the inverter 42 instead of or in addition to the engine 14. The electric motor MG converts the power of the engine 14 and the driven force input from the drive wheel 38 side into electric energy by regeneration, and stores the electric energy in the power storage device 44 via the inverter 42. The electric motor MG is connected to a power transmission path between the clutch K0 and the torque converter 16, and power is transmitted between the electric motor MG and the pump impeller 16a. Therefore, the electric motor MG is connected to the transmission input shaft 34 of the automatic transmission 18 so as to be able to transmit power without using the clutch K0.

The clutch K0 is, for example, a wet multi-plate hydraulic friction engagement device, and is engaged / released controlled by the hydraulic control circuit 40 using the hydraulic pressure generated by the oil pump 22 as a source pressure. In the engagement release control, the torque capacity of the clutch K0 (hereinafter referred to as K0 torque) is changed by adjusting the pressure of a linear solenoid valve or the like in the hydraulic control circuit 40, for example. In the engaged state of the clutch K0, the pump impeller 16a and the engine 14 are integrally rotated via the engine connecting shaft 32. On the other hand, in the released state of the clutch K0, power transmission between the engine 14 and the pump impeller 16a is interrupted. That is, the engine 14 and the driving wheel 38 are disconnected by releasing the clutch K0. Since the electric motor MG is connected to the pump impeller 16a, the clutch K0 is provided in a power transmission path between the engine 14 and the electric motor MG, and also functions as a clutch that connects and disconnects the power transmission path.

2, the engine 14 is a known direct-injection type four-cycle gasoline engine that directly injects fuel into each cylinder (cylinder) 50, for example. The engine 14 includes a combustion chamber 52 provided between a cylinder head and a piston, an intake pipe 54 connected to an intake port of the combustion chamber 52, and an exhaust pipe 56 connected to an exhaust port of the combustion chamber 52. A fuel injection device 58 provided in the cylinder head for directly injecting fuel F into the combustion chamber 52; an ignition device 60 for igniting an air-fuel mixture in the combustion chamber 52; and an intake valve for opening or closing the intake port of the combustion chamber 52 62, an exhaust valve 64 that opens or closes the exhaust port of the combustion chamber 52, an intake valve drive device 66 that opens and closes by reciprocating the intake valve 62 in synchronization with the rotation of the crankshaft 36, and an exhaust valve 64 And an exhaust valve driving device 68 that opens and closes by reciprocating in synchronization with the rotation of the crankshaft 36.

An electronic throttle valve 70 is provided in the intake pipe 54 of the engine 14, and the electronic throttle valve 70 is opened and closed by a throttle actuator 72. In the engine 14, the fuel F is injected and supplied from the fuel injection device 58 to the intake air sucked into the combustion chamber 52 from the intake pipe 54 to form a mixture, and the mixture is ignited and burned by the ignition device 60. . Thereby, the engine 14 is driven, and the air-fuel mixture after combustion is sent into the exhaust pipe 56 as exhaust gas.

The intake valve driving device 66 also has a function of appropriately changing the valve opening timing VTin of the intake valve 62, for example, and also functions as a valve timing changing mechanism VVT that changes the valve opening timing VTin of the intake valve 62, for example. Various types of operating principles of the intake valve driving device 66 are generally known. For example, the intake valve drive device 66 is a cam mechanism that interlocks with the rotation of the crankshaft 36, and selectively opens or closes the intake valve 62 by using one of a plurality of cams having different shapes by hydraulic control or electric control. The intake valve 62 may be opened and closed by utilizing a cam mechanism that is linked to the rotation of the crankshaft 36 and a mechanism that changes the cam phase of the cam mechanism by hydraulic control or electric control. It may be made to do. In short, the intake valve driving device 66 is configured mainly by the cam mechanism, for example, and may have any function of advancing or retarding both the opening timing and closing timing of the intake valve 62.

FIG. 3 is a diagram for explaining the opening timing VTin of the intake valve 62 and the opening timing VTex of the exhaust valve 64. In FIG. 3, the arrows A1 and A2 indicate the valve opening timing VTin of the intake valve 62, that is, the range of the crank angle Acr in which the intake valve 62 is open. An arrow B indicates the valve opening timing VTex of the exhaust valve 64, that is, the range of the crank angle Acr at which the exhaust valve 64 is open. The valve opening timing VT in the present embodiment is a period during which the valve is opened (valve opening time) from the time when the valve opens (valve opening time) to the time when the valve closes (valve closing time), and indicates the valve opening time. is not. An arrow A1 indicates the most retarded state (most retarded position) in which the valve opening timing VTin of the intake valve 62 is shifted by the maximum in the retarded direction by the intake valve driving device 66. On the other hand, an arrow A2 indicates a most advanced angle state (most advanced angle position) in which the valve opening timing VTin of the intake valve 62 is shifted by the maximum in the advance direction by the intake valve driving device 66. The most retarded position of the intake valve 62 is, for example, a reference position when the engine is stopped due to ignition off. In the present embodiment, for example, at the time of engine start accompanying idling on or during idling, the valve opening timing VTin of the intake valve 62 is set as the reference position. For example, when the engine 14 is operated in the middle load range, the valve opening timing VTin of the intake valve 62 is shifted in the advance direction. As described above, in the engine 14 of this embodiment, the valve opening timing VTin of the intake valve 62 can be changed within the range of the arrow AR by the intake valve driving device 66.

1 and 2, the vehicle 10 is provided with an electronic control device 90 including a control device for the vehicle 10 related to, for example, the engagement release control of the clutch K0 and the start control of the engine 14. The electronic control unit 90 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM and follows a program stored in the ROM in advance. Various controls of the vehicle 10 are executed by performing signal processing. For example, the electronic control unit 90 performs output control of the engine 14, drive control of the motor MG including regeneration control of the motor MG, shift control of the automatic transmission 18, torque capacity control of the clutch K0, and the like. If necessary, it is configured separately for engine control, motor control, hydraulic control, and the like. As shown in FIGS. 1 and 2, the electronic control unit 90 includes various sensors (for example, an engine rotational speed sensor 74, a turbine rotational speed sensor 76, an output shaft rotational speed sensor 78, an electric motor rotational speed sensor 80, an accelerator opening sensor 82). , Various signals (for example, the engine rotation speed Ne and the crank angle Acr, which are the rotation speed of the engine 14, the turbine rotation speed) based on the detection values by the throttle sensor 84, the air flow meter 86, the intake valve side cam position sensor 88, the battery sensor 89, and the like. Nt, that is, the transmission input rotation speed Nin that is the rotation speed of the transmission input shaft 36, the transmission output rotation speed Nout that is the rotation speed of the transmission output shaft 24 corresponding to the vehicle speed V, and the motor rotation that is the rotation speed of the motor MG. Speed Nm, accelerator opening θacc corresponding to the driver's demand for driving the vehicle 10, Throttle valve opening θth representing the opening angle of the throttle valve 70, the intake air amount Qair of the engine 14, the camshaft angle Aca, state of charge of the power storage device 44 such as a (charging capacity) SOC) is supplied. As shown in FIGS. 1 and 2, for example, the engine control command signal Se for controlling the output of the engine 14, the motor control command signal Sm for controlling the operation of the motor MG, the clutch K 0, A hydraulic command signal Sp for operating an electromagnetic valve (solenoid valve) or the like included in the hydraulic control circuit 40 to control the hydraulic actuator of the automatic transmission 18 includes a fuel injection device 58, an ignition device 60, and an intake valve drive. It is output to the engine 66, the engine control device such as the throttle actuator 72, the inverter 42, the hydraulic control circuit 40, etc.

FIG. 4 is a functional block diagram for explaining a main part of the control function by the electronic control unit 90. In FIG. 4, the hybrid control means, that is, the hybrid control unit 92 controls a function as an engine drive control unit that controls driving of the engine 14 and an operation as a driving force source or a generator by the electric motor MG via the inverter 42. A function as an electric motor operation control unit is included, and hybrid drive control by the engine 14 and the electric motor MG is executed by these control functions. For example, the hybrid control unit 92 calculates a required driving force Fdtgt as a required driving amount for the vehicle 10 by the driver based on the accelerator opening θacc and the vehicle speed V. Then, the hybrid control unit 92 considers transmission loss, auxiliary load, gear ratio γ of the automatic transmission 18, charge capacity SOC of the power storage device 44, and the like, and a driving power source for driving that can obtain the required driving force Fdtgt. Command signals (engine output control command signal Se and motor control command signal Sm) for controlling the driving force source for traveling are output so as to be the output of (engine 14 and motor MG). The required drive amount includes, in addition to the required drive force Fdtgt [N] in the drive wheel 38, the required drive torque [Nm] in the drive wheel 38, the required drive power [W] in the drive wheel 38, and the transmission output shaft 24. The required transmission output torque or the like can also be used. Further, the accelerator opening degree θacc [%], the intake air amount Qair [g / sec], or the like can also be used as the required drive amount.

Specifically, for example, when the required driving force Fdtgt is within a range that can be covered only by the output of the electric motor MG, the hybrid control unit 92 uses only the electric motor MG as a driving power source for traveling with the clutch K0 released. A traveling motor (EV traveling) is performed. On the other hand, for example, when the required driving force Fdtgt is in a range that cannot be covered unless at least the output of the engine 14 is used, the hybrid control unit 92 uses at least the engine 14 for traveling with the clutch K0 engaged. An engine traveling that travels as a driving force source, that is, a hybrid traveling (EHV traveling) is performed. In addition, the hybrid control unit 92 requests charging of the power storage device 44 when EV driving cannot be performed because discharge of the power storage device 44 is restricted based on, for example, dischargeable power calculated from the charge capacity SOC or the power storage device temperature. If the engine 14 or the equipment related to the engine 14 needs to be warmed up, the engine 14 is operated.

Here, as a method for starting the engine 14 by the hybrid control unit 92, for example, the engine 14 is cranked by the electric motor MG by controlling the released clutch K0 toward the engagement, and the fuel supply or the engine ignition is performed. And the engine 14 is started. In this starting method, the clutch K0 is controlled so that a K0 torque for transmitting an engine starting torque, which is a torque necessary for starting the engine, to the engine 14 side can be obtained. Since the engine start torque corresponds to the MG torque Tm that flows to the engine 14 side via the clutch K0, the MG torque Tm that flows to the drive wheel 38 side is reduced by that amount. For this reason, this starting method corresponds to K0 torque for transmitting the engine starting torque to the engine 14 side in addition to the MG torque Tm necessary for satisfying the required driving torque in order to suppress the drop of the driving torque. MG torque to be increased (hereinafter, this increase is referred to as K0 compensation torque (or MG compensation torque)).

In the EV traveling according to the present embodiment, the EV traveling region is reduced by as much as the MG compensation torque is secured in preparation for the engine start with respect to the maximum MG torque Tm that the electric motor MG can output. In other words, if the MG compensation torque can be suppressed, the EV travel range can be expanded. Therefore, the hybrid control unit 92 executes engine start by ignition start in addition to the start method for controlling the clutch K0 toward engagement. That is, the hybrid control unit 92 covers a part of the engine starting torque by performing the ignition start. In the engine starting method by ignition start, for example, fuel is injected into the cylinder of the engine 14 stopped in the expansion stroke and ignited (ignition) to burn the cylinder, and the piston is pushed down by the generated explosion torque. The engine 14 is started by rotating the crankshaft 36.

When a part of the engine starting torque is covered by the ignition start, it is preferable to perform the ignition start in order to move the stopped piston. That is, it is suitable for suppressing the MG compensation torque to overcome the friction torque of the engine 14 at the start of the engine start by the explosion torque accompanying the start of ignition. Therefore, when restart of the engine 14 is requested during EV traveling, the hybrid control unit 92 first performs ignition start and rotates the engine 14. Thereafter, the hybrid control unit 92 increases the engine rotational speed Ne by the electric motor MG by controlling the clutch K0 toward engagement. Then, after the engine rotation speed Ne is synchronized with the motor rotation speed Nmg, the hybrid control unit 92 completely engages the clutch K0 and shifts to EHV traveling. The friction torque of the engine 14 at the time of starting the engine is a compression torque corresponding to the pumping loss, a mechanical friction torque corresponding to the sliding resistance, and a mechanical friction torque of the intake valve driving device 66 and the exhaust valve driving device 68. Total torque. However, the friction torque of the engine 14 at the start of the engine start when moving the stopped piston is exclusively the sliding resistance and the mechanical friction torque of the intake valve driving device 66 and the like because the engine rotational speed Ne is extremely low. Become.

By the way, when the engine 14 is started, first, even if the cylinder stopped in the expansion stroke by the ignition start is burned, the engine 14 is in a region where the explosion torque sufficient to exceed the friction torque of the engine 14 cannot be generated. Any of the cylinders may be stopped. For example, as shown in FIG. 5A, this is a case where any cylinder of the engine 14 is stopped at the top dead center (TDC). FIG. 5 is a diagram for explaining the ignition start when the TDC is stopped, exemplifying a 6-cylinder engine.

In FIG. 5A, when a cylinder A stops at TDC, the cylinder B stopped in the expansion stroke has the exhaust valve 64 immediately before opening. Therefore, even if the ignition is started for the cylinder B, the explosion torque is made smaller than when the ignition is started at a position where the exhaust valve 64 is not immediately opened. Then, in this ignition start, there is a possibility that an explosion torque sufficient to exceed the friction torque of the engine 14 may not be generated. Therefore, when the engine is started by the ignition start, the hybrid control unit 92 burns the cylinder C stopped in the compression stroke and negatively rotates the engine 14, and then burns the cylinder B in the expansion stroke to burn the engine 14 Perform reverse rotation starting to rotate forward. The negative rotation of the engine 14 is, for example, a rotation in a direction opposite to the positive rotation when the rotation when the engine 14 is driven to rotate during traveling of the vehicle is a positive rotation. Therefore, negatively rotating the engine 14 is to reverse the engine 14.

At this time, as shown in FIG. 5 (a), if the valve opening timing VTin of the intake valve 62 is set to the most retarded position which is a reference position when the engine is stopped by ignition off, for example, the intake valve 62 stops in the compression stroke. In the cylinder C, the intake valve 62 is still open. For this reason, even if the ignition start is performed for the cylinder C, the explosion torque is reduced as compared with the case where the intake valve 62 is closed. Then, in this ignition start, the engine 14 may not be rotated negatively. Therefore, as shown in FIG. 5 (b), the hybrid control unit 92 operates the intake valve drive device 66 to change the valve opening timing VTin of the intake valve 62 to the advance side prior to starting ignition of the cylinder C. Then, the cylinder C is sealed. For example, the hybrid control unit 92 changes the valve opening timing VTin of the intake valve 62 to the most advanced position. Then, as shown in FIG. 5C, the hybrid control unit 92 stops in the compression stroke by the ignition start in a state in which the valve opening timing VTin of the intake valve 62 is advanced by the intake valve driving device 66. The cylinder C is burned and the engine 14 is rotated negatively. As a result, a state in which a certain cylinder A stops at TDC is avoided, and air is compressed again in the cylinder B in the expansion stroke.

Thereafter, as shown in FIG. 5 (d), the hybrid control unit 92 causes the cylinder B to burn by starting ignition and causes the engine 14 to rotate in the forward direction in a state where the cylinder B in the expansion stroke is compressed. Thereby, coupled with the fact that the exhaust valve 64 is not immediately opened, an explosion torque sufficient to exceed the friction torque of the engine 14 is generated. The hybrid control unit 92 increases the engine rotational speed Ne by controlling the clutch K0 toward engagement when the engine 14 is normally rotated in the ignition start by the reverse rotation start. At this time, in the third explosion when the cylinder B is the first explosion, the ignition start is already performed and the cylinder C containing a large amount of combustion gas is burned, so that the engine rotation speed Ne is increased. Therefore, the occurrence of an overshoot in which the engine speed Ne exceeds the motor speed Nm is suppressed. Accordingly, the timing for completely engaging the clutch K0 is advanced, and the vehicle can quickly shift to EHV traveling. Therefore, in addition to improving the startability of the engine 14, acceleration response and drivability are improved.

Here, when the engine 14 is rotating negatively due to the ignition start for the cylinder C, the air in the combustion chamber 52 is in a flowing state in the cylinder B in the expansion stroke. Therefore, the hybrid control unit 92 performs fuel injection to the cylinder B in the expansion stroke while the engine 14 is negatively rotating in the reverse rotation start. Thereby, the homogenization of the air-fuel mixture in the combustion chamber 52 of the cylinder B in the expansion stroke is promoted, and a sufficient explosion torque is generated.

Also, it is considered that the compression of the cylinder B in the expansion stroke due to the negative rotation of the engine 14 is maximized when the negative rotation stops. In addition, when the negative rotation stops, it is considered that the reaction force against the positive rotation force becomes zero. Therefore, the hybrid control unit 92, when starting the reverse rotation, when the negative rotation speed of the engine 14 is decreasing (for example, when the negative rotation speed approaches zero or when the negative rotation stops). The cylinder B in the expansion stroke is ignited. As a result, when the air compression is increased as much as possible, the cylinder B in the expansion stroke is burned, and a sufficient explosion torque is generated. Further, when the reaction torque is suppressed as much as possible, the cylinder B in the expansion stroke is burned, and the engine 14 is properly rotated in the forward direction.

Further, in order to properly reverse the negative rotation of the engine 14 to the positive rotation, it is necessary to start ignition in the cylinder B while the cylinder B is in the expansion stroke. Therefore, the hybrid control unit 92 performs ignition of the cylinder B in the expansion stroke until the cylinder B in the expansion stroke reaches the top dead center in the reverse rotation start. Thereby, reverse rotation start is performed appropriately.

More specifically, returning to FIG. 4, the traveling state determination means, that is, the traveling state determination unit 94 determines whether or not there is an engine stop request for requesting the stop of the engine 14 on the assumption of restart. For example, the traveling state determination unit 94 determines that the required driving force Fdtgt is within a range that can be covered only by the output of the electric motor MG during EHV traveling, or the discharge restriction of the power storage device 44, the charging request of the power storage device 44, the engine 14 and the like. When the warm-up request is canceled and EV traveling is performed, it is determined that there is an engine stop request on the assumption of restart.

The traveling state determination unit 94 determines whether or not there is an engine restart request for requesting restart of the engine 14 that has been temporarily stopped, for example. For example, the traveling state determination unit 94 may determine that the required driving force Fdtgt is in a range that cannot be covered unless at least the output of the engine 14 is used during EV traveling, or the discharge limitation of the power storage device 44 is performed, or When a request for charging the power storage device 44 is made, it is determined that there is an engine restart request.

The engine state determination means, that is, the engine state determination unit 96, for example, when it is determined by the traveling state determination unit 94 that there is an engine stop request on the premise of restarting, or the traveling state determination unit 94 issues an engine restart request. If it is determined that there is, it is determined whether or not the opening timing VTin of the intake valve 62 matches the engine restart. For example, the engine state determination unit 96 determines whether or not the opening timing VTin of the intake valve 62 is advanced by a predetermined amount or more with respect to the most retarded position, or the opening timing VTin of the intake valve 62 is the maximum. It is determined whether or not the opening timing VTin of the intake valve 62 matches the engine restart based on whether or not the advance angle position is set.

The engine state determination unit 96 determines, for example, whether any cylinder of the stopped engine 14 is stopped at TDC. Further, the engine state determination unit 96 determines whether or not the rotation of the engine 14 has actually started reverse rotation by the start of reverse rotation start by the hybrid control unit 92, for example. Further, the engine state determination unit 96 determines whether or not the ignition condition for the cylinder in the expansion stroke is satisfied after fuel is injected into the cylinder in the expansion stroke that is executed in the reverse rotation start by the hybrid control unit 92, for example. To do. That is, the engine state determination unit 96 determines whether or not ignition to the cylinder in the expansion stroke has become possible. This ignition condition is, for example, whether the cylinder in the expansion stroke has not reached TDC and the negative rotation speed of the engine has been reduced or stopped in the engine 14 in reverse rotation.

The hybrid control unit 92 determines that there is an engine restart request by the traveling state determination unit 94 and determines that any cylinder of the engine 14 stopped by the engine state determination unit 96 is stopped at TDC. In the case where it is determined, the ignition start by the reverse rotation start is performed in a state where the valve opening timing VTin of the intake valve 62 is advanced.

FIG. 6 is a flowchart for explaining a main part of the control operation of the electronic control unit 90, that is, a control operation for improving the engine startability at the time of engine start by ignition start, for example, an extremely short cycle of about several msec to several tens msec. It is executed repeatedly in time.

In FIG. 6, first, in step (hereinafter, step is omitted) S10 corresponding to the traveling state determination unit 94, it is determined whether there is an engine stop request based on restart, for example. If the determination in S10 is negative, this routine is terminated. If the determination is positive, in S20 corresponding to the engine state determination unit 96, for example, the valve opening timing VTin of the intake valve 62 matches the engine restart. It is determined whether or not there is. If the determination in S20 is negative, in S30 corresponding to the hybrid control unit 92, for example, the intake valve driving device 66 is operated, and the valve opening timing VTin of the intake valve 62 is changed to the advance side. After execution of S30, the process returns to S20. If the determination in S20 is affirmative, for example, both fuel injection and ignition for the engine 14 are stopped in S40 corresponding to the hybrid control unit 92. Next, in S50 corresponding to the engine state determination unit 96, for example, the crank angle Acr of the stopped engine 14 is detected. Next, in S60 corresponding to the engine state determination unit 96, for example, it is determined whether any cylinder of the stopped engine 14 is stopped at TDC. If the determination in S60 is negative, it is determined in S70 corresponding to the traveling state determination unit 94, for example, whether there is an engine restart request. If the determination in S70 is negative, this S70 is repeatedly executed. If the determination is affirmative, in S80 corresponding to the hybrid control unit 92, for example, ignition start is executed for a cylinder stopped in the expansion stroke. Is done. On the other hand, when the determination in S60 is affirmed, it is determined in S90 corresponding to the traveling state determination unit 94 whether, for example, there is an engine restart request. If the determination in S90 is negative, this S90 is repeatedly executed, but if the determination is affirmative, in S100 corresponding to the hybrid control unit 92, for example, fuel injection and ignition for a cylinder stopped in the compression stroke, for example. Is executed and the reverse rotation start is started. Next, in S110 corresponding to the engine state determination unit 96, for example, it is determined whether or not the rotation of the engine 14 has started reverse rotation. If the determination in S110 is negative, this S110 is repeatedly executed. If the determination is affirmative, in S120 corresponding to the hybrid control unit 92, for example, fuel injection is executed for a cylinder in the expansion stroke. Next, in S130 corresponding to the engine state determination unit 96, for example, it is determined whether or not an ignition condition for a cylinder in the expansion stroke is satisfied. If the determination in S130 is negative, this S130 is repeatedly executed. If the determination is positive, in S140 corresponding to the hybrid control unit 92, for example, ignition is executed for a cylinder in the expansion stroke.

As described above, according to the present embodiment, the cylinder in the expansion stroke is compressed again due to the negative rotation of the engine 14 by the reverse rotation start, and a high explosion torque can be obtained at the first explosion of the cylinder. Further, after the initial explosion of the cylinder in the expansion stroke, the cylinder containing a large amount of combustion gas in the reverse rotation start is burned, so the explosion torque at the time of combustion of the cylinder is reduced. Accordingly, by suppressing the explosion torque of the second or third explosion, the increase in the engine rotational speed Ne is loosened, the occurrence of overshoot is suppressed, and the clutch K0 is fully engaged immediately. Therefore, the engine startability can be improved when the engine is started by the ignition start.

Further, according to the present embodiment, when any cylinder of the engine 14 is stopped at the top dead center, the reverse rotation is performed, so that the engine startability can be improved.

Further, according to the present embodiment, in the reverse rotation start, the fuel injection to the cylinder in the expansion stroke is performed while the engine 14 is rotating negatively, so that the fuel flows in a state where air flow is generated in the cylinder due to the negative rotation. It is injected and the homogenization of the air-fuel mixture in the cylinder in the expansion stroke is promoted. Therefore, the initial explosion of the cylinder in the expansion stroke is likely to occur, and a high explosion torque is easily obtained at the initial explosion, so that the engine startability can be improved.

Further, according to this embodiment, in the reverse rotation start, the ignition of the cylinder in the expansion stroke is performed when the speed of the negative rotation of the engine 14 is decreasing, so that the air compression of the cylinder in the expansion stroke proceeds. It is burned in the state. In addition, the first explosion of the cylinder in the expansion stroke is generated in a state where the reaction torque accompanying the negative rotation of the engine is small. Therefore, the first explosion itself of the cylinder in the expansion stroke is likely to occur, and a high explosion torque is easily obtained at the first explosion, so that the engine startability can be further improved.

Further, according to the present embodiment, in the reverse rotation start, the cylinder in the expansion stroke is ignited until the cylinder in the expansion stroke reaches the top dead center. Startability can be improved.

Further, according to this embodiment, in the reverse rotation start, the combustion of the cylinders stopped in the compression stroke is performed in a state where the valve opening timing VTin of the intake valve 62 is advanced by the intake valve driving device 66. Therefore, the cylinder stopped in the compression stroke is combusted while the intake valve 62 is securely closed.

Further, according to the present embodiment, when the engine 14 is normally rotated in the reverse rotation start, the engine rotational speed Ne is increased by controlling the clutch K0 toward the engagement, so that the clutch K0 is performed by performing the reverse rotation first. The MG torque Tm when controlling toward the engagement is suppressed. Therefore, during EV travel, the MG torque Tm secured for engine start is suppressed, and the EV travel range is expanded. In addition, since the occurrence of overshoot is suppressed by performing reverse rotation start, the clutch K0 is quickly fully engaged. Therefore, the engine startability can be improved when the engine is started by the ignition start.

As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

For example, in the above-described embodiment, the state in which the cylinder of the engine 14 is stopped at the TDC is illustrated as an aspect of the reverse rotation start, but the present invention is not limited to this aspect. For example, the reverse rotation start may be performed even when the vehicle is stopped with a certain degree of deviation from the TDC. For example, in a cylinder that deviates to some extent from TDC and stops in the expansion stroke, although the exhaust valve 64 is not immediately opened during forward rotation, ignition occurs because the crank angle Acr is small with respect to TDC. There is a possibility that the forward rotation does not start even if the engine is started. In addition, when an ignition start is performed on a cylinder that is stopped in the expansion stroke prior to the cylinder in a state where the cylinder is stopped to some extent toward the compression stroke with respect to TDC, the exhaust valve 64 is used. However, there is a possibility that sufficient explosion torque cannot be obtained. Therefore, even when the vehicle is stopped with a certain degree of deviation from the TDC, the reverse rotation start is executed in the same manner as when the vehicle is stopped in accordance with the TDC. That is, reverse rotation start is performed when any cylinder of the engine 14 is stopped in a predetermined region across the TDC. When one of the cylinders of the engine 14 is stopped in a predetermined region sandwiching the TDC, when the engine is started, the friction torque of the engine 14 is set even if the cylinder stopped in the expansion stroke is first burned. This is a case where one of the cylinders of the engine 14 is stopped in a region where an explosion torque sufficient to exceed the range cannot be generated. Accordingly, when any cylinder of the engine 14 is stopped in a predetermined region sandwiching the TDC, the engine startability can be improved by performing the reverse rotation start.

In the flowchart of FIG. 6 in the above-described embodiment, in S20 and S30, when the engine is stopped, the valve opening timing VTin of the intake valve 62 is advanced with respect to the most retarded position that is the reference position. It is not restricted to this aspect. For example, if the intake valve drive device 66 is a mechanism that can change the valve opening timing VTin of the intake valve 62 even when the engine is stopped, such as an electrically controlled valve opening / closing mechanism, the engine is started after the engine is stopped and before the engine is restarted. The valve opening timing VTin of the intake valve 62 may be advanced during the period until. That is, S20 and S30 may be completed before S100 is executed. In addition, when the reference position of the intake valve 62 when the engine is stopped due to the ignition off is an intermediate position between the most retarded angle position and the most advanced angle position, the intermediate position matches the engine restart. If it is a position, S20 and S30 may not be present. Note that if the reference position of the intake valve 62 originally matches the engine restart, the intake valve driving device 66 does not need to have the function of the valve timing changing mechanism VVT. Apart from this, in the flowchart of FIG. 6, it is determined in S110 whether or not the rotation of the engine 14 has started reverse rotation, but this is not a limitation. For example, in S110, it may be determined whether or not the rotation of the engine 14 is reverse. As described above, in the flowchart of FIG. 6, the execution contents of each step, the execution order thereof, and the like can be changed as appropriate without departing from the scope.

In the above-described embodiment, as shown in FIG. 5, the 6-cylinder engine is exemplified to explain the reverse start, but the engine to which the present invention is applied is not limited to this 6-cylinder engine. For example, a 5-cylinder engine or an 8-cylinder engine may be used.

In the above-described embodiment, only the intake valve driving device 66 has the function of the valve timing changing mechanism VVT. However, the exhaust valve driving device 68 also changes the valve timing changing mechanism VTex of the exhaust valve 64. You may have a function of VVT. With the function of the valve timing changing mechanism VVT in the exhaust valve driving device 68, for example, when starting ignition with respect to a cylinder in the expansion stroke in reverse rotation start, the valve opening timing VTex of the exhaust valve 64 may be retarded. In this way, since the opening of the exhaust valve 64 is delayed when the cylinder in the expansion stroke is combusted, the explosion torque when the engine 14 is normally rotated in the reverse rotation start can be obtained more sufficiently.

Further, the function of the valve timing changing mechanism VVT in the above-described embodiment is to advance or retard both the valve opening time and the valve closing time, but is not limited to this mode. For example, the intake valve driving device 66 has the function of a valve timing changing mechanism VVT that can be electromagnetically controlled to open and close the valve independently of the rotation of the crankshaft 36 without being mechanically connected to the crankshaft 36. May be. In such a case, it is possible to advance only the valve closing time without changing the valve opening time of the intake valve 62, or to delay only the valve opening time without changing the valve closing time of the exhaust valve 64.

In the above-described embodiment, the clutch K0 is completely engaged after the engine rotation speed Ne and the motor rotation speed Nmg are synchronized. However, the present invention is not limited to this. For example, since the increase in the engine rotational speed Ne is moderated by the reverse rotation start, the clutch K0 may be completely engaged when the engine rotational speed Ne is changing toward synchronization with the electric motor rotational speed Nmg. . In this way, although it is somewhat disadvantageous for suppressing the shock, the response of starting the engine is improved.

In the above-described embodiment, the ignition start is executed and the engine 14 is started by the electric motor MG. However, the present invention is not limited to this mode. For example, the engine 14 may be started by a starter motor provided separately from the electric motor MG while assisting by ignition start. For example, if the engine can be started only by starting ignition, it is not necessary to start the engine 14 by the electric motor MG (or starter). In short, the present invention can be applied as long as ignition start is executed when the engine 14 is started.

In the above-described embodiment, the vehicle 10 is provided with the torque converter 16 and the automatic transmission 18, but the torque converter 16 and the automatic transmission 18 are not necessarily provided.

It should be noted that what has been described above is only one embodiment, and the present invention can be carried out in various modifications and improvements based on the knowledge of those skilled in the art.

10: Vehicle 14: Engine 62: Intake valve 66: Intake valve drive device (valve timing changing mechanism)
90: Electronic control device (control device)
K0: Engine disconnection clutch (clutch)
MG: Electric motor

Claims

A vehicle control device comprising an engine, an electric motor, and a clutch provided in a power transmission path between the engine and the electric motor,
When the engine is started, the engine cylinder stopped in the compression stroke is burned to rotate the engine negatively, and then the engine cylinder in the expansion stroke is burned to rotate the engine forward. A control apparatus for a vehicle, characterized by starting.
2. The vehicle control device according to claim 1, wherein the reverse rotation start is performed when any cylinder of the engine is stopped in a predetermined region sandwiching a top dead center.
3. The vehicle control device according to claim 1, wherein the fuel injection to the cylinder of the engine in the expansion stroke is performed while the engine is negatively rotating.
4. The vehicle control device according to claim 1, wherein ignition of the cylinder of the engine in the expansion stroke is performed when a negative rotation speed of the engine is decreasing. 5. .
The vehicle according to any one of claims 1 to 4, wherein the ignition of the cylinder of the engine in the expansion stroke is performed until the cylinder of the engine in the expansion stroke reaches a top dead center. Control device.
A valve timing changing mechanism for changing the opening timing of the intake valve of the engine,
6. The combustion of the cylinder of the engine stopped in the compression stroke is performed in a state where the valve opening timing of the intake valve is advanced by the valve timing changing mechanism. The vehicle control device according to any one of the preceding claims.
The vehicle according to any one of claims 1 to 6, wherein when the engine rotates forward during the reverse rotation start, the rotation speed of the engine is increased by controlling the clutch toward engagement. Control device.