WO2015040474A1

WO2015040474A1 - Hybrid vehicle, controller for hybrid vehicle and control method for hybrid vehicle for delivering power to an external device and optimizing startability and fuel consumption with a variable valve timing at the intake

Info

Publication number: WO2015040474A1
Application number: PCT/IB2014/001866
Authority: WO
Inventors: Yoshikazu Asami; Toshikazu Kato; Ryuta Teraya
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2013-09-19
Filing date: 2014-09-18
Publication date: 2015-03-26
Also published as: JP2015058827A

Abstract

A hybrid vehicle includes an internal combustion engine, an electric power output device and a controller. The electric power output device is configured to output electric power to a device outside the vehicle. The electric power is generated by using the internal combustion engine. The internal combustion engine includes a variable valve actuating device for changing an operation characteristic of an intake valve. The controller is configured to set at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power- output device to the device outside the vehicle is smaller than the corresponding at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle. The controller is configured to start up the internal combustion engine.

Description

HYBRID VEHICLE, CONTROLLER FOR HYBRID VEHICLE AND CONTROL METHOD FOR HYBRID VEHICLE FOR DELIVERING POWER TO AN EXTERNAL DEVICE AND OPTIMIZING STARTABILITY AND FUEL CONSUMPTION WITH A VARIABLE VALVE TIMING AT THE INTAKE

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a hybrid vehicle, a controller for the hybrid vehicle and a control method for the hybrid vehicle and, more particularly, to a hybrid vehicle including an internal combustion engine that includes a variable valve actuating device for changing the operation characteristic of an intake valve, a controller for the hybrid vehicle and a control method for the hybrid vehicle.

2. Description of Related Art

[0002] There is known an internal combustion engine including a variable valve actuating device that is able to change the operation characteristic of an intake valve. There is also known a variable valve actuating device that is able to change at least one of the valve lift and valve operating angle of an intake valve as such a variable valve actuating device (see Japanese Patent Application Publication No. 2000-34913 (JP 2000-34913 A), Japanese Patent Application Publication No. 2007-71083 (JP 2007-71083 A), Japanese Patent Application Publication No. 2004-183610 (JP 2004-183610 A), Japanese Patent Application Publication No. 2013-53610 (JP 2013-53610 A), Japanese Patent Application Publication No. 2008-25550 (JP 2008-25550 A), Japanese Patent Application Publication No. 2012-117376 (JP 2012-117376 A), Japanese Patent Application Publication No. 9-242519 (JP 9-242519 A), and the like).

[0003] For example, JP 2000-34913 A describes a variable valve actuating device that is able to change the valve operating angle of each intake valve by allowing the valve lift of each intake valve of an internal combustion engine to be variable. In this variable valve actuating device, the valve operating angle of each intake valve is set to a maximum region by driving a variable valve lift actuator for the intake valves when the internal combustion engine is started. Thus, decompression occurs, with the result that vibrations are suppressed at start-up of the internal combustion engine (see JP 2000-34913 A). SUMMARY OF THE INVENTION

[0004] In a hybrid vehicle in which a driving electric motor is mounted in addition to an internal combustion engine, the stop and start frequency of the internal combustion engine is high, so the technique described in JP 2000-34913 A is useful in terms that it is possible to suppress vibrations at start-up of the internal combustion engine. However;:if the valve operating angle (or valve lift) of each intake valve is increased, the output response of the internal combustion engine decreases, with the result that the operating point of the internal combustion engine reaches an optimal fuel economy region at a lower response after start-up of the internal combustion engine.

[0005] Particularly, in a hybrid vehicle that is able to supply electric power to a device outside the vehicle while the vehicle is stopped (hereinafter, supplying electric power to a device outside the vehicle is also referred to as "external power feeding"), when the internal combustion engine is started because of a decrease in the state of charge (SOC) of an electrical storage device during external power feeding, it is desired to suppress a fuel consumption of the internal combustion engine by raising the response at which the operating point of the internal combustion engine reaches the optimal fuel economy region in preference to suppressing vibrations at start-up of the internal combustion engine.

[0006] The invention provides a hybrid vehicle that is able to carry out external power feeding and that improves fuel economy of an internal combustion engine that can be started during external power feeding, and a control method for the hybrid vehicle.

[0007] A first aspect of the invention provides a hybrid vehicle. The hybrid vehicle includes an internal combustion engine, an electric power output device and a controller. The electric power output device is configured to output electric power to a device outside the vehicle. The electric power is generated by using the internal combustion engine. . The internal combustion engine includes a variable valve actuating device. The variable valve actuating device is configured to change an operation characteristic of an intake valve. The controller is configured to (a) set at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power output device to the device outside the vehicle is smaller than the corresponding at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle, and (b) start up the internal combustion engine.

[0008] In the above aspect, the variable valve actuating device may be configured to change the operation characteristic of the intake valve to one of a first characteristic and a second characteristic. At least one of the valve lift and the valve operating angle of the second characteristic may be larger than the corresponding at least one of the valve lift and the valve operating angle of the first characteristic. When the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the controller may be configured to set the operation characteristic of the intake valve to the first characteristic and then start up the internal combustion engine.

[0009] In the above aspect, the variable valve actuating device may be configured to change the operation characteristic of the intake valve to any one of a first characteristic, a second characteristic and a third characteristic. At least one of the valve lift and the valve operating angle of the second characteristic may be larger than the corresponding at least one of the valve lift and the valve operating angle of the first characteristic. At least one of the valve lift and the valve operating angle of the third characteristic may be larger than the corresponding at least one of the valve lift and the valve operating angle of the second characteristic. When the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the controller may be configured to set the operation characteristic of the intake valve to the first characteristic and then start up the internal combustion engine. [0010] In the above aspect, the internal combustion engine may further include a circulation device. The circulation device may be configured to circulate exhaust gas from the internal combustion engine to an intake side of the internal combustion engine. The controller may be configured to start circulation of exhaust gas after start-up of the internal combustion engine. The controller may be configured to start the circulation of the exhaust gas earlier when electric power is output by the electric power output device to the device outside the vehicle than when electric power is not output by the electric power output device to the device outside the vehicle.

[0011] In the above aspect, the hybrid vehicle may further include an electrical storage device. The electrical storage device is configured toh store electric power generated by using the internal combustion engine. The controller may be configured to start up the internal combustion engine when a state quantity of the electrical storage device is lower than a predetermined threshold, the state quantity may be a value indicating a state of charge of the electrical storage device, and the controller may be configured to set the threshold such that the threshold at the time when electric power is output by the electric power output device to the device outside the vehicle is lower than the threshold at the time when electric power is not output by the electric power output device to the device outside the vehicle.

[0012] Another aspect of the invention provides a control method for a hybrid vehicle. The hybrid vehicle includes an internal combustion engine, an electric power output device and a controller. The electric power output device is configured to output electric power to a device outside the vehicle. The electric power is generated by using the internal combustion engine. The internal combustion engine includes a variable valve actuating device. The variable valve actuating device is configured to change an operation characteristic of an intake valve. The control method includes: (A) determining, by the controller, whether outputting electric power by the electric power output device is required; (B) setting, by the controller, at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power output device to the device outside the vehicle is smaller than the corresponding at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle; and (C) starting up the internal combustion engine by the controller.

[0013] Further another aspect of the invention provides a controller for a hybrid vehicle. The hybrid vehicle includes an internal combustion engine and an electric power output device. The internal combustion engine includes a variable valve actuating device. The variable valve actuating device is configured to change an operation characteristic of an intake valve. The electric power output device is configured to output electric power to a device outside the vehicle. The electric power is generated by using the internal combustion engine. The controller includes a valve actuation control unit and a HV control unit. The valve actuation control unit is configured to set at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power output device to the device outside the vehicle is smaller than the corresponding at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle. The HV control unit is configured to start up the internal combustion engine when electric power is output by the electric power output device to the device outside the vehicle.

[0014] In the above aspect, the variable valve actuating device may be configured to change the operation characteristic of the intake valve to one of a first characteristic and a second characteristic. At least one of the valve lift and the valve operating angle of the second characteristic may be larger than the corresponding at least one of the valve lift and the valve operating angle of the first characteristic. When the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the valve actuation control unit may. be configured to set the operation characteristic of the intake valve to the first characteristic and then the HV control unit may be configured to start up the internal combustion engine.

[0015] In the above aspect, the variable valve actuating device may be configured to change the operation characteristic of the intake valve to any one of a first characteristic, a second characteristic and a third characteristic. At least one of the valve lift and the valve operating angle of the second characteristic may be larger than the corresponding at least one of the valve lift and the valve operating angle of the first characteristic. At least one of the valve lift and the valve operating angle of the third characteristic may be larger than the corresponding at least one of the valve lift and the valve operating angle of the second characteristic. When the internal comb!ustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the valve actuation control unit may be configured to set the operation characteristic of the intake valve to the first characteristic and then the HV control unit may be configured to start up the internal combustion engine.

[0016] In the above aspect, the internal combustion engine may include a circulation device. The circulation device may be configured to circulate exhaust gas from the internal combustion engine to an intake side of the internal combustion engine. The HV control unit may be configured to start circulation of exhaust gas after start-up of the internal combustion engine. And the HV control unit may be configured to start the circulation of exhaust gas earlier when electric power is output by the electric power output device to the device outside the vehicle than when electric power is not output by the electric power output device to the device outside the vehicle.

[0017] In the above aspect, the hybrid vehicle may further include an electrical storage device configured to store electric power generated by using the internal combustion engine. The controller may further include a SOC calculation unit configured to calculate a state quality of the electrical storage device. The state quantity may be a value indicating a state of charge of the electrical storage device. The HV control unit may be configured to start up the internal combustion engine when a state quantity of the electrical storage device is lower than a predeterm ined threshold. And the SOC calculation unit may be configured to set the threshold such that the threshold at the time when electric power is output by the electric power output device to the device outside the vehicle is lower than the threshold at the time when electric power is not output by the electric power output device to the device outside the vehicle.

[0018] According to the invention, the internal combustion engine is started up in a state where at least one of the valve lift of the intake valve and the valve operating angle of the intake valve is smaller when external power feeding is carried out than when external power feeding is not carried out. Thus, it is possible to increase the output response of the internal combustion engine at start-up of the internal combustion engine during external power feeding, so the operating point of the internal combustion engine early reaches the optimal fuel economy region. Thus, according to the invention, it is possible to improve fuel economy of the internal combustion engine during external power feeding. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a block diagram that shows the overall configuration of a hybrid vehicle according to a first embodiment of the invention;

FIG. 2 is a configuration view of an engine shown in FIG. 1 ;

FIG. 3 is a graph that shows the correlation between a crank angle and a valve displacement that is achieved by a VVL device;

FIG. 4 is a front view of the VVL device;

FIG. 5 is a perspective view that partially shows the VVL device shown in FIG. 4;

FIG. 6 is a view that illustrates an operation at the time when the valve lift and valve operating angle of each intake valve are large;

FIG. 7 is a view that illustrates an operation at the time when the valve lift and valve operating angle of each intake valve are small; FIG. 8 is a graph that shows the correlation between an engine rotation speed and an engine torque;

FIG. 9 is a graph that shows a temporal change in engine rotation speed after engine start-up is started;

FIG. 10 is a functional block diagram of a controller shown in FIG. 1 ;

FIG. 11 is a flowchart for illustrating control over the VVL device by the controller; FIG. 12 is a configuration view of an engine according to a second embodiment; FIG. 13 is a time chart that shows a change in the open timing of an EGR valve at the time when the operation characteristic (valve lift and valve operating angle) of each intake valve is changed; P

FIG. 14 is a flowchart for illustrating control that is executed by a controller according to the second embodiment;

FIG. 15 is a graph that shows a temporal change in engine rotation speed, cranking torque and the SOC of an electrical storage device;

FIG. 16 is a flowchart for illustrating control over a VVL device by a controller according to a third embodiment;

FIG. 17 is a graph that shows the correlation between a crank angle and a valve displacement that is achieved by a VVL device that is able to change the operation characteristic of each intake valve in three steps;

FIG. 18 is a graph that shows an operating line of an engine including the VVL device having operation characteristics shown in FIG. 17;

FIG. 19 is a flowchart for illustrating an example of control over the VVL device having the operation characteristics shown in FIG. 17; and

FIG. 20 is a graph that shows the correlation between a crank angle and a valve displacement that is achieved by a VVL device that is able to change the operation characteristic of each intake valve in two steps.

DETAILED DESCRIPTION OF EMBODIMENTS

[0020] Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. The plurality of embodiments will be described below; however, appropriate combinations of the configurations described in the embodiments are assumed at the time of filing. Like reference numerals denote the same or corresponding portions in the drawings, and the description thereof will not be repeated.

[0021] FIG. 1 is a block diagram that shows the overall configuration of a hybrid vehicle according to a first embodiment of the invention. As shown in FIG. 1 , the hybrid vehicle 1 includes an engine 100, motor generators MG 1 , MG2, a power split device 4, a reduction gear 5, and drive wheels 6. The hybrid vehicle 1 further includes an electrical storage device B, a power control unit (PCU) 20, a voltage converter 30, an external power feeding port 40 and a controller 200.

[0022] The hybrid vehicle 1 is able to travel by using driving force that is output from at least one of the engine 100 and the motor generator MG2. The power split device 4 is configured to be able to split driving force, which is generated by the engine 100, into driving force for driving the drive wheels 6 and driving force for driving the motor generator MG1. The power split device 4 is formed of, for example, a planetary gear train.

[0023] The engine 100 generates driving force for the vehicle. The engine 100 generates driving force for driving the motor generator MG 1 that is able to operate as a generator. The engine lOOxan be cranked by the motor generator MG 1 to start up. The engine 100 includes a variable valve actuating device for changing the operation characteristic of each intake valve. The variable valve actuating device is controlled by the controller 200 on the basis of a traveling condition of the vehicle and whether external power feeding is required. The configuration of the engine 100 and variable valve actuating device will be described in detail later.

[0024] Each of the motor generators MG1 , MG2 is an alternating-current rotary electric machine, and is, for example, a three-phase alternating-current synchronous motor generator. The motor generator MG 1 can generate electric power by using the driving force of the engine 100. For example, when the SOC of the electrical storage device B reaches a predetermined lower limit, the engine 100 starts up, and electric power is generated by the motor generator MG 1. Electric power generated by the motor generator

MG 1 is converted in voltage by the PCU 20. The converted electric power is temporarily stored in the electrical storage device B, or the converted electric power is directly supplied to the motor generator MG2, or the converted electric power is further converted in voltage by the voltage converter 30 and is then supplied through the external power feeding port 40 to a device outside the vehicle during external power feeding.

[0025] The motor generator MG2 generates driving force by using at least one of electric power stored in the electrical storage device B and electric power generated by the motor generator MG 1. The driving force of the motor generator MG2 is transmitted to the drive wheels 6 via the reduction gear 5. In FIG. 1 , the drive wheels 6 are front wheels. i

Instead of the front wheels or in addition to the front wheels, rear wheels may be driven by the motor generator MG2.

[0026] During braking of the vehicle, the motor generator MG2 is driven by the drive wheels 6 via the reduction gear 5, and the motor generator G2 operates as a generator. Thus, the motor generator MG2 operates as a regenerative brake that converts braking energy to electric power. Electric power generated by the motor generator MG2 is stored in the electrical storage device B.

[0027] The PCU 20 is a drive unit for driving the motor generators MG 1 , MG2.

The PCU 20 includes an inverter for driving the motor generators MG1 , MG2, and can further include a converter for converting voltage between the inverter and the electrical storage device B.

[0028] The electrical storage device B is a rechargeable direct-current power supply, and includes, for example, a nickel-metal hydride secondary battery or a lithium ion secondary battery. The voltage of the electrical storage device B is, for example, about 200 V. The electrical storage device B stores electric power generated by the motor generators MG 1 , MG2. A large-capacitance capacitor may also be employed as the electrical storage device B. The electrical storage device B may be any electric power buffer as long as the electric power buffer is able to temporarily store electric power generated by the motor generators MG 1 , MG2 and supply the stored electric power to the motor generator MG2 or the voltage converter 30. The electrical storage device B detects the voltage VB and current IB of the electrical storage device B, and outputs those detected values to the controller 200.

[0029] The voltage converter 30 is driven during external power feeding by a driving signal DS that is received from the controller 200, converts the voltage of electric power that is received from at least one of the electrical storage device B and the PCU 20, and outputs the resultant electric power to the external power feeding port 40. More specifically, the voltage converter 30 directly receives electric power, generated by the motor generator MG 1 by using the engine 100, from the PCU 20 or from the electrical storage device B that temporarily stores the generated electric power, converts the voltage of the electric power for external power feeding, and then outputs the resultant electric power to the external power feeding port 40. The voltage converter 30 is formed of, for example, an inverter. The voltage converter 30 may be configured to bidirectionally convert voltage. Thus, the voltage converter 30 is able to convert the voltage of electric power that is supplied from a power supply outside the vehicle and that is input from the external power feeding port 40, and is able to charge the electrical storage device B with the resultant electric power. The external power feeding port 40 is an electric pow er interface for supplying electric power to a device outside the vehicle during external power feeding.

[0030] The controller 200 includes an electronic control unit (ECU) that includes a central processing unit (CPU), a storage device, input/output buffers, and the like (which are not shown). The controller 200 receives signals from various sensors and outputs control signals to devices, and executes control over the devices in the hybrid vehicle 1. As an example, the controller 200 executes traveling control over the hybrid vehicle 1 , charging control over the electrical storage device B, control over the engine 100 including the variable valve actuating device, external power feeding control by using the voltage converter 30, and the like. The configuration of the controller 200 will be described later.

[0031] FIG. 2 is a configuration view of the engine 100 shown in FIG. shown in FIG. 2, air is taken into the engine 100 through an air cleaner 102. An intake air amount is adjusted by a throttle valve 104. The throttle valve 104 is driven by a throttle motor 312.

[0032] Intake air is mixed with fuel in each cylinder 106 (combustion chamber). Fuel is injected from each injector 108 to the corresponding cylinder 106. In this embodiment, the engine 100 will be described as a port injection type in which an injection hole of the injector 108 is provided in an intake port. In addition to the port injection injector 108, a direct injection injector that directly injects fuel into the corresponding cylinder 106 may be provided. Furthermore, only a direct injection injector may be provided. '.·'*

[0033] Air-fuel mixture in each cylinder 106 is ignited by an ignition plug 110 to combust. The combusted air-fuel mixture, that is, exhaust gas, is purified by a three-way catalyst 112, and is then emitted to the outside of the vehicle. A piston 114 is pushed -downward by combustion of air-fuel mixture, and a crankshaft 116 rotates.

[0034] An intake valve 118 and an exhaust valve 120 are provided at the top portion of each cylinder 106. The amount of air that is introduced into each cylinder 106 and the timing of introduction are controlled by the corresponding intake valve 118. The amount of exhaust gas that is emitted from each cylinder 106 and the timing of emission are controlled by the corresponding exhaust valve 120. Each intake valve 118 is driven by a cam 122. Each exhaust valve 120 is driven by a cam 124.

[0035] As will be described in detail later, the valve lift and valve operating angle of each intake valve 118 are controlled by a variable valve lift (VVL) device 400. The valve lift and valve operating angle of each exhaust valve 120 may also be controllable. A variable valve timing (VVT) device that controls the open/close timing of each valve may be combined with the VVL device 400.

[0036] The controller 200 controls a throttle opening degree 0th, an ignition timing, a fuel injection timing, a fuel injection amount, and the operating state (open/close timing, valve lift, valve operating angle, and the like) of each intake valve so that the engine 100 is placed in a desired operating state. Signals are input to the controller 200 from various sensors, that is, a cam angle sensor 300, a crank angle sensor 302, a knock sensor 304 and a throttle opening degree sensor 306.

[0037] The cam angle sensor 300 outputs a signal indicating a cam position. The crank angle sensor 302 outputs signals indicating the rotation speed of the crankshaft 116 (engine rotation speed) and the rotation angle of the crankshaft 116. The knock sensor 304 outputs a signal indicating the strength of vibrations of the engine 100. The throttle opening degree sensor 306 outputs a signal indicating the throttle opening degree Oth.

[0038] The controller 200 receives a signal PS from an external power feeding switch 308. The external power feeding switch 308 is a switch for a user to require external power feeding. When the external power feeding switch 308 is turned on, the signal PS is activated. As for a request for external power feeding, without providing the external power feeding switch 308, for example, when a power feeding connector is connected to the external power feeding port 40 or when a power feeding request signal is received from the power feeding connector connected to the external power feeding port 40, it may be determined that there is a request for external power feeding. The controller 200 controls the engine 100 on the basis of the signals from these sensors and external power feeding switch 308.

[0039] FIG. 3 is a graph that shows the correlation between a crank angle and a valve displacement that is achieved by the VVL device 400. As shown in FIG. 3, each exhaust valve 120 (FIG. 2) opens and closes in an exhaust stroke, and each intake valve 118 (FIG. 2) opens and closes in an intake stroke. A waveform EX indicates the valve displacement of each exhaust valve 120. Waveforms IN I , IN2 each indicate a valve displacement of each intake valve 118. The valve displacement is a displacement of a valve from a state where the valve is closed, In the following description, the valve lift is a valve displacement at the time when the opening degree of the intake valve 118 has reached a peak, and the valve operating angle is a crank angle of a period from when the intake valve 118 opens to when the intake valve 118 closes.

[0040] The operation characteristic of each intake valve 118 is changed by the VVL device 400 between the waveforms IN I , IN2. The waveform IN I indicates the case where the valve lift and the valve operating angle are minimum. The waveform IN2 indicates the case where the valve lift and the valve operating angle are maximum. In the VVL device 400, the valve operating angle increases with an increase in the valve lift.

[0041] FIG. 4 is a front view of the VVL device 400. The configuration shown in FIG. 4 is one example. The VVL device 400 is not limited to such a configuration. As shown in FIG. 4, the VVL device 400 includes a drive shaft 410, a support pipe 420, an input arm 430, and oscillation cams 440. The drive shaft 410 extends in one direction. The support pipe 420 covers the outer periphery of the drive shaft 410. The input arm 430 and the oscillation cams 440 are arranged in the axial direction of the drive shaft 410 on the outer periphery of the support pipe 420. An actuator (not shown) that linearly actuates the drive shaft 410 is connected to the distal end of the drive shaft 410.

[0042] The VVL device 400 includes the single input arm 430 in correspondence with the single cam 122 provided in each cylinder. The two oscillation cams 440 are provided on both sides of each input arm 430 in correspondence with the pair of intake valves 118 provided for each cylinder.

[0043] The support pipe 420 is formed in a hollow cylindrical shape, and is arranged parallel to a camshaft 130. The support pipe 420 is fixed to a cylinder head so as not to be moved in the axial direction or rotated.

[0044] The drive shaft 410 is inserted inside the support pipe 420 so as to be slidable in the axial direction, The input arm 430 and the two oscillation cams 440 are provided on the outer periphery of the support pipe 420 so as to be oscillatable about the axis of the drive shaft 410 and not to move in the axial direction.

[0045] The input arm 430 includes an arm portion 432 and a roller portion 434. The arm portion 432 protrudes in a direction away from the outer periphery of the support pipe 420. The roller portion 434 is rotatably connected to the distal end of the arm portion 432. The input arm 430 is provided such that the roller portion 434 is arranged at a position at which the roller portion 434 is able to contact the cam 122.

[0046] Each oscillation cam 440 has a substantially triangular nose portion 442 that protrudes in a direction away from the outer periphery of the support pipe 420. A concave cam face 444 is formed at one side of the nose portion 442. A roller rotatably attached to a rocker arm 128 is pressed against the cam face 444 by the urging force of a valve spring provided in the intake valve 118.

[0047] The input arm 430 and the oscillation cams 440 integrally oscillate about the axis of the drive shaft 410. Therefore, as the camshaft 130 rotates, the input arm 430 that is in contact with the cam 122 oscillates, and the oscillation cams 440 oscillate in interlocking with movement of the input arm 430. The movements of the oscillation cams 440 are transferred to the intake valves 118 via rocker arms 128, and the intake valves 118 are opened or closed, ί

[0048] The VVL device 400 further includes a device that changes a relative phase difference between the input arm 430 and each oscillation cam 440 around the axis of the support pipe 420. The valve lift and valve operating angle of each intake valve 118 are changed as needed by the device that changes the relative phase difference.

[0049] That is, when the relative phase difference between the input arm 430 and each oscillation cam 440 is increased, the oscillation angle of each rocker arm 128 is increased with respect to the oscillation angle of each of the input arm 430 and the oscillation cams 440, and the valve lift and valve operating angle of each intake valve 118 are increased.

[0050] When the relative phase difference between the input arm 430 and each oscillation cam 440 is reduced, the oscillation angle of each rocker arm 128 is reduced with respect to the oscillation angle of each of the input arm 430 and the oscillation cams 440, and the valve lift and valve operating angle of each intake valve 118 are reduced.

[0051] FIG. 5 is a perspective view that partially shows the VVL device 400 shown in FIG. 4. FIG. 5 shows a structure with part cut away so that the internal structure is understood. As shown in FIG. 5, a slider gear 450 is accommodated in a space defined between the outer periphery of the support pipe 420 and the set of input arm 430 and two oscillation cams 440. The slider gear 450 is supported on the support pipe 420 so as to be rotatable and slidable in the axial direction. The slider gear 450 is provided on the support pipe 420 so as to be slidable in the axial direction.

[0052] The slider gear 450 includes a helical gear 452. The helical gear 452 is located at the center portion of the slider gear 450 in the axial direction. Right-handed screw spiral helical splines are formed on the helical gear 452. The slider gear 450 includes helical gears 454. The helical gears 454 are respectively located on both sides of the helical gear 452. Left-handed screw spiral helical splines opposite to those of the helical gear 452 are formed on each of the helical gears 454.

[0053] On the other hand, helical splines corresponding to the helical gears 452, 454 are respectively formed on the inner peripheries of the input arm 430 and two oscillation cams 440. The inner peripheries of the input arm 430 and two oscillation cams 440 define a space in which the slider gear 450 is accommodated. That is, the right-handed spiral helical splines are formed on the input arm 430, and the helical splines are in mesh with the helical gear 452. The left-handed spiral helical splines are formed on each of the oscillation cams 440, and the helical splines are in mesh with the corresponding helical gear 454.

[0054] An oblong hole 456 is formed in the slider gear 450. The oblong hole 456 is located between the helical gear 452 and one of the helical gears 454, and extends in the circumferential direction. Although not shown in the drawing, an oblong hole is formed in the support pipe 420, and the oblong hole extends in the axial direction so as to partially overlap with the oblong hole 456. A locking pin 412 is integrally provided in the drive shaft 410 inserted inside the support pipe 420. The locking pin 412 protrudes through the overlapped portions of these oblong hole 456 and oblong hole (not shown).

[0055] When the drive shaft 410 is moved in the axial direction by the actuator (not shown) coupled to the drive shaft 410, the slider gear 450 is pressed by the locking pin 412, and the helical gears 452, 454 move in the axial direction of the drive shaft 410 at the same time. When the helical gears 452, 454 are moved in this way, the input arm 430 and the oscillation cams 440 spline-engaged with these helical gears 452, 454 do not move in the axial direction. Therefore, the input arm 430 and the oscillation cams 440 pivot around the axis of the drive shaft 410 through meshing of the helical splines. [0056] At this time, the helical splines respectively formed on the input arm 430 and each oscillation cam 440 have opposite orientations. Therefore, the pivot direction of the input arm 430 and the pivot direction of each oscillation cam 440 are opposite to each other. Thus, the relative phase difference between the input arm 430 and each oscillation cam 440 changes, with the result that the valve lift and valve operating angle of each intake valve 118 are changed as is already described.

[0057] The VVL device 400 is not limited to this type. For example, a VVL device that electrically drives each valve, a VVL device that hydraulically drives each valve, or the like, may be used.

[0058] The controller 200 controls the valve lift and valve operating angle of each intake valve 118 by adjusting an operation amount of the actuator that linearly moves the drive shaft 410.

[0059] FIG. 6 is a view that illustrates an operation at the time when the valve lift and valve operating angle of each intake valve 118 are large. FIG. 7 is a view that illustrates an operation at the time when the valve lift and valve operating angle of each intake valve 118 are small. As shown in FIG. 6 and FIG. 7, when the valve lift and valve operating angle of each intake valve 118 are large, because the close timing of each intake valve 118 delays, the engine 100 runs on the Atkinson cycle. That is, part of air taken into the cylinder 106 in the intake stroke is returned to the outside of the cylinder 106, so compression reaction that is a force for compressing air decreases in the compression stroke. Thus, it is possible to reduce vibrations at engine start-up. Because the compression ratio decreases, ignitability deteriorates, and the output response of the engine 100 decreases.

[0060] On the other hand, when the valve lift and valve operating angle of each intake valve 118 are small, because the close timing of each intake valve 118 advances, the compression ratio increases. Thus, ignitability improves at a low temperature, and the output response of the engine improves. Because the compression reaction increase, vibrations at engine start-up can increase.

[0061] FIG. 8 and FIG. 9 are graphs for illustrating a change in the output response of the engine 100 at the time when the operation characteristic (valve lift and valve operating angle) of each intake valve 118 is changed. FIG. 8 shows the correlation between an engine rotation speed and an engine torque. FIG. 9 shows a temporal change in the engine rotation speed after engine start-up is started at time tl . In FIG. 8 and FIG. 9, the continuous line indicates the case where the valve lift and valve operating angle of each intake valve 118 are small (for example, minimum setting), and the dashed line indicates the case where the valve lift and valve operating angle of each intake valve 118 are large (for example, maximum setting).

[0062] As shown in FIG. 8, in the region in which the engine rotation speed is low, the engine torque in I b case where the valve lift and valve operating angle of each intake valve 118 are small is larger than the engine torque in the case where the valve lift and the valve operating angle are large. This is because part of air taken into the cylinder is returned to the outside of the cylinder when the valve lift and the valve operating angle are large, whereas the compression ratio increases because each intake valve 118 is closed early when the valve lift and the valve operating angle are small.

[0063] In the region in which the engine rotation speed is high, the engine torque in the case where the valve lift and valve operating angle of each intake valve 118 are large is larger than the engine torque in the case where the valve lift and the valve operating angle are small. This is because, in the region in which the engine rotation speed is high, a large amount of air is introduced into the cylinder by the inertial force of air even when the close timing of each intake valve 118 is delayed.

[0064] Thus, as shown in FIG. 9, when the engine 100 is started up and the engine rotation speed is increased to a predetermined value A, it is possible to increase the engine torque in a low rotation speed region in the case where the valve lift and the valve operating angle are reduced, and the engine rotation speed quickly increases to the predetermined value A. The predetermined value A is, for example, an engine rotation speed corresponding to an operating point within an optimal fuel economy region in the low rotation speed region of the engine 100.

[0065] Referring back to. FIG. 8, each of the lines LI to L3 indicates an equal fuel consumption line, and fuel economy is higher in order of the lines LI to L3. As is apparent from FIG. 8, the operating point of the engine 100 reaches a desired fuel economy region at a lower engine rotation speed in the case where the valve lift and the valve operating angle are small than in the case where the valve lift and the valve operating angle are large. The rate of increase in the engine rotation speed in the case where the valve lift and the valve operating angle are small is higher than the rate of increase in the engine rotation speed in the case where the valve lift and the valve operating angle are large. Thus, it is possible to more quickly increase the engine rotation speed to an optimal fuel economy region (for example, within the line L3) at start-up of the engine 100 in the case where the valve lift and the valve operating angle are small than in the case where the valve lift and the valve operating angle are large.

[0066] In the first embodiment, when the engine 100 is started up in the case where external power feeding is carried out during a stop of the vehicle, the engine 100 is started up in a state where the valve lift and valve operating angle of each intake valve 118 are reduced (for example, minimum setting) by giving a higher priority to fuel economy improvement than suppression of vibrations at engine start-up. When the engine 100 is started up in the case where external power feeding is not carried out (for example, during traveling), the engine 100 is started up in a state where the valve lift and valve operating angle of each intake valve 118 are increased in order to suppress vibrations at engine start-up with consideration for ride comfort.

[0067] FIG. 10 is a functional block diagram of the controller 200. As show n in FIG. 10, the controller 200 includes an SOC calculation unit 202, an HV control unit 204, an external power feeding control unit 206 and a valve actuation control unit 208. The SOC calculation unit 202 calculates the SOC of the electrical storage device B on the basis of the detected values of the voltage VB and current IB of the electrical storage device B. Various known methods may be used for a method of calculating the SOC.

[0068] The HV control unit 204 executes general control over the hybrid vehicle 1. Typically, the HV control unit 204 generates an engine start-up command and starts up the engine 100 when a vehicle power exceeds a threshold during traveling in an EV mode in a state where the engine 100 is stopped or when the SOC of the electrical storage device B becomes lower than a predetermined lower limit.

[0069] The external power feeding control unit 206 sets an operation mode to an "external power feeding mode" when the external power feeding switch 308 (FIG. 2) is turned on during a stop of the hybrid vehicle 1. In the external power feeding mode, the external power feeding control unit 206 generates the driving signal DS for driving the voltage converter 30 (FIG. 1), and outputs the driving signal DS to the voltage converter 30. In the external power feeding mode, the external power feeding control unit 206 provides notification that the operation mode is set to the external power feeding mode, to the valve actuation control unit 208.

[0070] When the valve actuation control unit 208 has received from the external power feeding control unit 206 the notification that the operation mode is set to the external power feeding mode, the valve actuation control unit 208 controls the VVL device 400 such that the valve lift and valve operating angle of each intake valve 118 are smaller than those when the valve actuation control unit 208 has not received the notification. As one example, in the external power feeding mode, the valve actuation control unit 208 generates a signal VLV instructing to set the valve lift and valve operating angle of each intake valve 118 to small values, and outputs the signal VLV to the VVL device 400. On the other hand, not in the external power feeding mode, the valve actuation control unit 208 generates the signal VLV instructing to set the valve lift and valve operating angle of each intake valve 118 to large values, and outputs the signal VLV to the VVL device 400.

[0071] FIG. 11 is a flowchart for illustrating control over the VVL device 400 by the controller 200. This flowchart is implemented by the controller 200 executing a prestored program at predetermined intervals. Alternatively, the processes of part of the steps may be implemented by constructing exclusive hardware (electronic circuit).

[0072] As shown in FIG. 11, the controller 200 determines whether the operation mode of the vehicle is the external power feeding mode (step S 10). When it is determined that the operation mode is the external power feeding mode (YES in step S10), the controller 200 , reduces the valve lift and valve operating angle of each intake valve 118 (FIG. 2) (for example, minimum setting) (step S20). On the other hand, when it is determined that the operation mode is not the external power feeding mode (NO in step S10), the controller 200 increases the valve lift and valve operating angle of each intake valve 118 as compared to those in the external power feeding mode (step S30).

[0073] Subsequently, the controller 200 determines whether a start-up condition of the engine 100 is satisfied (step S40). For example, when the vehicle power exceeds the predetermined threshold during traveling in the EV mode, when the SOC of the electrical storage device B becomes lower than the predetermined lower limit or when an electric power that is allowed to be supplied from the electrical storage device B to a device outside the vehicle becomes insufficient during external power feeding (when the SOC is low or when a required electric power is high), it is determined that the engine start-up condition is satisfied. When it is determined that the engine start-up condition is satisfied (YES in step S40), the controller 200 starts up the engine 100 (step S50). That is, when the electric power that is allowed to be supplied from the electrical storage device B to a device outside the vehicle becomes insufficient in the external power feeding mode, the controller 200 starts up the engine 100 in a state where the valve lift and valve operating angle of each intake valve 118 are reduced.

[0074] As described above, in this first embodiment, during external power feeding, the engine 100 is started up in a state where the valve lift and valve operating angle of each intake valve 118 are small as compared to those when external power feeding is not carried out. Thus, it is possible to increase the output response of the engine 100 at the time when the engine 100 starts up during external power feeding, so the operating point of the engine 100 early reaches the optimal fuel economy region. Thus, according to this first embodiment, it is possible to improve fuel economy of the engine 100 during external power feeding,

[0075] FIG. 12 is a configuration view of an engine according to a second embodiment. As shown in FIG. 12, the engine 100A according to the second embodiment differs from the configuration of the engine 100 shown in FIG. 2 in that an external exhaust gas recirculation (EGR) device is further included. [0076] The external EGR device includes an EGR passage 140 and an EGR valve 142. The EGR passage 140 is a pipe for circulating exhaust gas from the engine 100A to an intake side (for example, an intake manifold) of the engine 100A. The EGR valve 142 is provided in the EGR passage 140, and its open/closed state is controlled by a controller 200A. When the EGR valve 142 is opened, an exhaust passage and an intake passage are communicated with each other by the EGR passage 140. When the EGR valve 142 is closed, the EGR passage 140 is interrupted. A throttle loss is reduced by circulating exhaust gas to the intake passage by opening the EGR valve 142, with the result that a pumping loss is reduced. Thus, it is possible to improve fuel economy by the external EGR device.

[0077] The controller 200A controls the open/closed state of the EGR valve 142. Specifically, at start-up of the engine 100A, the controller 200A changes the EGR valve 142 from the closed state to the open state when the engine rotation speed has increased to the predetermined value A (FIG. 8, FIG. 9) or near the predetermined value A. The other control of the controller 200A is the same as the controller 200 according to the first embodiment. The overall configuration of the hybrid vehicle according to the second embodiment is the same as that of the hybrid vehicle 1 shown in FIG. 1.

[0078] FIG. 13 is a time chart that shows a variation in the open timing of the EGR valve 142 at the time when the operation characteristic (valve lift and valve operating angle) of each intake valve 118 is changed. As shown in FIG. 13, the continuous line indicates the case where the valve lift and valve operating angle of each intake valve 118 are small, and the dashed line indicates the case where the valve lift and valve operating angle of each intake valve 118 are large. A variation in the engine rotation speed at the time when the operation characteristic (valve lift and valve operating angle) of each intake valve 118 is changed is as described with reference to FIG. 8 and FIG. 9.

[0079] Engine start-up is started at time t l , and the EGR valve 142 is opened as the engine rotation speed increases. As described above, because the engine rotation speed is quickly increased when the valve lift and valve operating angle of each intake valve 118 are reduced, so it is possible to open the EGR valve 142 at an« earlier timing when the valve lift and the valve operating angle are small than when the valve lift and the valve operating angle are large. As a result, the effect of improving fuel economy by EGR is early obtained.

[0080] FIG. 14 is a flowchart for illustrating control of the controller 200A according to the second embodiment. This flowchart shown in FIG. 14 differs from the flowchart shown in FIG. 11 in that step S52 and step S54 are further included. That is, when start-up of the engine 100A is started in step S50, the controller 200A determines whether the rotation speed of the engine 100A has reached the predetermined value A (step S52). As described above, the predetermined value A is, for example, an engine rotation speed corresponding to the operating point within the optimal fuel economy region in a low rotation speed range of the engine 100A.

[0081] When it is determined in step S52 that the engine rotation speed has^' become higher than or equal to the predetermined value A (YES in step S52), the controller 200A changes the EGR valve 142 from the closed state to the open state (step S54). That is, in the external power feeding mode, the engine 100A starts up in a state where the valve lift and valve operating angle of each intake valve 118 are small, so the engine rotation speed quickly increases, with the result that EGR is early introduced.

[0082] As described above, in this second embodiment, in the external power feeding mode, EGR is early introduced as compared to not in the external power feeding mode. Thus, according to this second embodiment, it is possible to further improve fuel economy during external power feeding.

[0083] In the external power feeding mode, when the SOC of the electrical storage device B is sufficient, electric power stored in the electrical storage device B is supplied to a device outside the vehicle (electric power stored in the electrical storage device B is electric power that is generated by using the engine and that is temporarily stored). When the SOC decreases, the engine 100 is started up, and, after, start-up of the engine, electric power generated by the motor generator MG 1 by using the engine 100 is directly supplied to a device outside the vehicle. At start-up of the engine, electric power is supplied from the electrical storage device B to the motor generator MG 1 , and the engine 100 is cranked by the motor generator MG 1.

[0084] When the valve lift and valve operating angle of each intake valve 118 are reduced, the startabilitv of the engine 100 improves, and it is possible to start up the engine 100 with cranking torque smaller than that in the case where the valve lift and the valve operating angle are large. That is, it is possible to suppress the electric power consumption of the electrical storage device B at engine start-up in the case where the valve lift and the valve operating angle are small as compared to the case where the valve lift and the valve operating angle are large. In this third embodiment, in the external power feeding mode, the valve lift and valve operating angle of each intake valve 118 are reduced and the lower limit of the SOC for starting up the engine 100 is reduced as compared to not in the external power feeding mode. Thus, the start-up frequency of the engine 100 in the external power feeding mode is reduced, so fuel economy is improved.

[0085] FIG. 15 is a graph that shows a temporal change in engine rotation speed, cranking torque and the SOC of the electrical storage device B. As shown in FIG 15, the continuous line indicates the case in the external power feeding mode, that is, the case where the valve lift and valve operating angle of each intake valve 118 are small, and the dashed line indicates the case not in the external power feeding mode, that is, the case where the valve lift and valve operating angle of each intake valve 118 are large.

[0086] In the external power feeding mode, cranking torque is smaller than that not in the external power feeding mode, and it is possible to suppress the electric power consumption of the electrical storage device B at engine start-up. Therefore, the lower limit of the SOC for generating electric power by starting up the engine 100 is reduced from a lower limit LL0, which is set for the case not in the external power feeding mode, to a lower limit LL.

[0087] Not in the external power feeding mode, the engine 100 starts up when the

SOC decreases to the lower limit LL0 (time tl , time t4). In the external power feeding mode, the engine 100 starts up when the SOC decreases to the lower limit LL lower than the lower limit LL0 (time t l , time t5 ). Either in the external power feeding mode or not in the external power feeding mode, the engine 100 stops when the SOC increases to a value UL (time t2, time t3, or the like).

[0088] An engine start-up interval not in the external power feeding mode (dashed line) is Tl (time tl to time t4), whereas an engine start-up interval in the external power feeding mode (continuous line) is T2 (time tl to time t5) longer than Tl . Thus, it is possible to reduce the engine start-up frequency in the external power feeding mode, and fuel economy is improved in this respect.

[0089] FIG. 16 is a flowchart for illustrating control over the VVL device 400 by the controller 200 according to the third embodiment. As shown in FIG. 16, this flowchart differs from the flowchart shown in FIG. 11 in that step S22 and step S32 are further included.

[0090] That is, when it is determined in step S10 that the operation mode is the external power feeding mode (YES in step S 10) and, after that, the valve lift and valve operating angle of each intake valve 118 are reduced (step S20), the controller 200 sets the SOC lower limit (the threshold for starting up the engine 100) to the lower limit LL (< LL0) (step S22).

[0091] On the other hand, when it is determined in step S 10 that the operation mode is not the external power feeding mode (NO in step S10) and, after that, the valve lift and valve operating angle of each intake valve 118 are increased (step S30), the controller 200 sets the SOC lower limit (the threshold for starting up the engine 100) to the lower limit LL0 (default value) (step S32).

[0092] After that, in step S40, it is determined whether the condition for starting up the engine 100 is satisfied. When the SOC becomes lower than the SOC lower limit set in step S22 or step S32, it is determined that the condition for starting up the engine 100 is satisfied.

[0093] According to this third embodiment, the start-up frequency of the engine

100 in the external power feeding mode is reduced, so it is possible to further improve fuel economy.

[0094] In the above-described third embodiment, description is made on the basis of the configuration of the first embodiment. Instead, the third embodiment may be combined with the second embodiment.

[0095] In the above-described embodiments, the valve lift and valve operating angle of each intake valve 118 may be changed continuously (steplessly) or may be changed discretely (stepwisely).

[0096] FIG. 17 is a graph that shows the correlation between a crank angle and a valve displacement that is achieved by a VVL device 400A that is able to change the operation characteristic of each intake valve 118 in three steps. The VVL device 400A is able to change the operation characteristic to any one of first to third characteristics. The first characteristic is indicated by a waveform INla. The second characteristic is indicated by a waveform IN2a. The valve lift and the valve operating angle in the second characteristic are larger than the valve lift and the valve operating angle in the first characteristic. The third characteristic is indicated by a waveform IN3a. The valve lift and the valve operating angle in the third characteristic are larger than the valve lift and the valve operating angle in the second characteristic.

[0097] FIG. 18 is a graph that shows an operating line of an engine 100B including the VVL device 400A having the operation characteristics shown in FIG. 17. As shown in FIG. 18, the abscissa axis represents engine rotation speed, and the ordinate axis represents engine torque. The lines indicated by the alternate long and short dashed line indicate torque characteristics - respectively corresponding to the first to third characteristics (IN l a to IN3a). The circles indicated by the continuous line indicate equal fuel consumption lines. The fuel economy improves as approaching the center of the circles. The engine 100B is basically operated along the engine operating line indicated by the continuous line.

[0098] In a low rotation speed region indicated by the region Rl , it is important to suppress vibrations at engine start-up. In this low rotation speed region, introduction of EGR gas is stopped, and fuel economy is improved by using the Atkinson cycle. Thus, in the region R l , the third -characteristic (IN3a) is selected as the operation characteristic of each intake valve 118 such that the valve lift and the valve operating angle increase. In an intermediate rotation speed region indicated by the region R2, fuel economy is improved by increasing the amount of introduction of EGR gas. Thus, in the region R2, the second characteristic (IN2a) is selected as the operation characteristic of each intake valve 118 such that the valve lift and the valve operating angle are intermediate.

[0099] That is, when the valve lift and valve operating angle of each intake valve 118 are large (third characteristic), improvement in fuel economy by using the Atkinson cycle is given a higher priority than improvement in fuel economy by introduction of EGR gas. On the other hand, when the intermediate valve lift and valve operating angle are selected (second characteristic), improvement in fuel economy by introduction of EGR gas is given a higher priority than improvement in fuel economy by using the Atkinson cycle.

[0100] In a high rotation speed region indicated by the region R3, a large amount of air is introduced into each cylinder by the inertia of intake air, and the output performance is improved by increasing an actual compression ratio. Thus, in the region R3, the third characteristic (lN3a) is selected as the operation characteristic of each intake valve 1 18 such that the valve lift and the valve operating angle increase.

[0101] When the engine 100B is operated at a high load in the low rotation speed region, when the engine 100B is started up at an extremely low temperature or when a catalyst is warmed up, the first characteristic (IN la) is selected as the operation characteristic of each intake valve 118 such that the valve lift and the valve operating angle reduce. In this way, the valve lift and the valve operating angle are determined on the basis of the operating state of the engine 100B.

[0102] FIG. 19 is a flowchart for illustrating an example of control over the VVL device 400A having the operation characteristics shown in FIG. 17. This flowchart shows the case where the engine includes the VVL device 400A in the first embodiment, and corresponds to FIG. 11 described in the first embodiment.

[0103] As shown in FIG. 19, this flowchart differs from the flowchart shown in

FIG. 11 in that step S24 and step S34 are included instead of step S20 and step S30. That is, when it is determined in step S10 that the operation mode is the external power feeding mode (YES in step S 10), the controller 200 gives a higher priority to ensuring the response of engine output than a reduction in shock at engine start-up, and controls the VVL device 400A such that the operation characteristic of each intake valve 118 is set to the first characteristic (INla) (step S24).

[0104] On the other hand, when it is determined in step S 10 that the operation mode is not the external power feeding mode (NO in step S10), the controller 200 controls the VVL device 400A such that the operation characteristic of each intake valve 118 is set to the third characteristic (IN3a) in order to reduce shock at engine start-up (step S34). If it is possible to sufficiently reduce shock at engine start-up when the operation characteristic of each intake valve 118 is the second characteristic (IN2a), the controller 200 may control the VVL device 400A in step S34 such that the operation characteristic of each intake valve 118 is set to the second characteristic (IN2a). ^¾

[0105] Although not shown in the drawings, similar control is executed on the VVL device 400A when the engine includes the VVL device 400A in the second embodiment or the third embodiment. That is, by replacing step S20 and step S30 with step S24 and step S34 in the flowchart shown in FIG. 14 according to the second embodiment, control in the case where the VVL device 400A is included is executed in the second embodiment. By replacing step S20 and step S30 with step S24 and step S34 in the flowchart shown in FIG. 16 according to the third embodiment, control in the case where the VVL device 400A is included is executed in the third embodiment.

[0106] With such a configuration, because the operation characteristic, that is, the valve lift and the valve operating angle, of each intake valve 118 is limited to three characteristics, it is possible to reduce a time that is required to adapt control parameters for controlling the operating state of the engine in comparison with the case where the valve lift and valve operating angle of each intake valve 118 continuously change. In addition, it is possible to reduce torque that is required of the actuator for changing the valve lift and valve operating angle of each intake valve 1 18, so it is possible to reduce the size and weight of the actuator. The manufacturing cost of the actuator can also be reduced.

[0107] FIG. 20 is a graph that shows the correlation between a crank angle and a valve displacement that is achieved by a VVL device 400B that is able to change the operation characteristic of each intake valve 118 in two steps. The VVL device 400B is able to change the operation characteristic to any one of first and second characteristics. The first characteristic is indicated by a waveform INl b. The second characteristic is indicated by a waveform IN2b. The valve lift and the valve operating angle in the second characteristic are larger than the valve lift and the valve operating angle in the first characteristic.

[0108] In this case, in the external power feeding mode, the engine is started up while the VVL device 400B is controlled such that the operation characteristic of each intake valve 118 is set to the first characteristic, whereas, not in the external power feeding mode, the engine is started up while the VVL device 400B is controlled s ich that the operation characteristic of each intake valve 118 is set to the second characteristic.

[0109] With such a configuration, because the operation characteristic, that is, the valve lift and the valve operating angle, of each intake valve 118 is limited to two characteristics, it is possible to further reduce a time that is required to adapt control parameters for controlling the operating state of the engine 100. It is also possible to further simplify the configuration of the actuator. The operation characteristic, that is, the valve lift and the valve operating angle, of each intake valve 118 is not limited to the case where the operation characteristic is changed in two steps or in three steps. The operation characteristic may be changed in any number of steps larger than or equal to four steps.

[0110] In the above-described embodiments, the valve operating angle of each intake valve 118 is changed together with the valve lift of each intake valve 118. However, the invention is also applicable to a hybrid vehicle including an engine that includes a variable valve actuating device that is able to change one of the valve lift of each intake valve 118 and the valve operating angle of each intake valve 118. With the variable valve actuating device that is able to change one of the valve lift and valve operating angle of each intake valve 118 as well, it is possible to obtain similar advantageous effects to those of the case where it is possible to change both the valve lift and valve operating angle of each intake valve 1 18. The variable valve actuating device that is able to change one of the valve lift and valve operating angle of each intake valve 118 may be implemented by utilizing various known techniques.

[0111] In the above-described embodiments, external power feeding is carried out during a stop of the hybrid vehicle 1. However, the invention is not limited to the case where external power feeding is cairied out during a stop of the vehicle. The invention is also applicable to the case where external power feeding is earned out during traveling of a hybrid vehicle that is able to carry out external power feeding during traveling.

[0112] In the above-described embodiments, the engine 100 (100A, 100B) is started up when the SOC of the electrical storage device B becomes lower than the predetermined lower limit. Instead of the SOC, the engine 100 (100A, 100B) may be started up when the voltage of the electrical storage device B becomes lower than a predetermined lower limit.

[0113] In the above-described embodiments, the series-parallel hybrid vehicle that is able to transmit the power of the engine 100 by distributing the power of the engine 100 to the drive wheels 6 and the motor generators MG 1 , MG2 by the power split device 4, The invention is also applicable to a hybrid vehicle of another type. That is, the invention is also applicable to, for example, a so-called series hybrid vehicle in which the engine 100 is only used to drive the motor generator MG 1 and the driving force of the vehicle is generated only by the motor generator MG2, a hybrid vehicle in which only regenerative ^■ energy within kinetic energy generated by the engine 100 is recovered as electric energy, a motor-assist hybrid vehicle in which the engine is used as a main power source and a motor, where necessary, assists, or the like. The invention is also applicable to a hybrid vehicle that travels only by using the power of the engine while the motor is separated.

[0114] In the above description, the engines 100, 100A, and 100B correspond to one example of an "internal combustion engine" according to the invention, and the voltage converter 30 and the external power feeding port 40 constitute one example of an "electric power output device" according to the invention. The VVL devices 400, 400A, 400B correspond to one example of a "variable valve actuating device" according to the invention. The external EGR device corresponds to one example of a "circulation device" according to the invention. [0115] The embodiments described above are expected to be implemented in appropriate combinations. The embodiments described above should be regarded as only illustrative in every respect and not restrictive. The scope of the invention is defined by the appended claims rather than the description of the above embodiments. The scope of the invention is intended to encompass all modifications within the scope of the appended claims and equivalents thereof.

Claims

CLAIMS :

1. A hybrid vehicle comprising:

an internal combustion engine including a variable valve actuating device, the variable valve actuating device being configured to change an operation characteristic of an intake valve;

an electric power output device configured to output electric power to a device outside the vehicle, the electric power being generated by using the internal combustion engine; and

a controller configured to:

(a) set at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve l i ft of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power output device to the device outside the veh icle is smaller than the corresponding at least one of the valve l ift of the intake val ve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle, and

(b) start up the internal combustion engine.

2. The hybrid vehicle according to claim 1 , wherein

the variable valve actuating device is configured to change the operation characteristic of the intake valve to one of a first characteristic and a second characteristic, at least one of the valve l ift and the valve operating angle in the second characteristic is larger than the corresponding at least one of the valve lift and the valve operating angle in the first characteristic, and

when the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the control ler is configured to set the operation characteristic of the intake valve to the first characteristic and then start up the internal combustion engi ne.

3. The hybrid vehicle according to claim 1 , wherein

the variable valve actuating device is configured to change the operation characteristic of the intake valve to any one of a first characteristic, a second characteristic and a third characteristic,

at least one of the valve lift and the valve operating angle of the second characteristic is larger than the corresponding at least one of the valve lift and the valve operating angle of the first characteristic,

at least one of the valve lift and the valve operating angle of the third characteristic is larger than the corresponding at least one of the valve lift and the valve operating angle of the second characteristic, and

when the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the controller is configured to set the operation characteristic of the intake valve to the first characteristic and then start up the internal combustion engine.

4. The hybrid vehicle according to any one of claims 1 to 3, wherein

the internal combustion engine includes a circulation device,

the circulation device is configured to circulate exhaust gas from the internal combustion engine to an intake side of the internal combustion engine,

the controller is configured to start circulation of exhaust gas after start-up of the internal combustion engine, and

the controller is configured to start the circulation of exhaust gas earl ier when electric power is output by the electric power output device to the device outside the vehicle than when electric power is not output by the electric power output device to the device outside the vehicle.

5. The hybrid vehicle according to any one of claims 1 to 4, further comprising: an electrical storage device configured to store electric power generated by using the internal combustion engine, wherein

the controller is configured to start up the internal combustion engine when a state quantity of the electrical storage device is lower than a predetermined threshold,

the state quantity is a value indicating a state of charge of the electrical storage device, and

the controller is configured to set the threshold such that the threshold at the time when electric power is output by the electric power output device to the device outside the vehicle is lower than the threshold at the time when electric power is not output by the electric power output device to the device outside the vehicle.

6. A control method for a hybrid vehicle, the hybrid vehicle including an internal combustion engine, an electric power output device and a controller, the internal combustion engine including a variable valve actuating device, the variable valve actuating dev ice being configured to change an operation characteristic of an intake valve, the electric power output device being configured to output electric powe r to a device outside the vehicle, the electric power being generated by using the internal combustion engine, the control method comprising:

(A) determining, by the controller, whether outputting electric power by the electric power output device is required;

(B) setting, by the controller, at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power output device to the device outside the vehicle is smaller than the corresponding at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle; and

(C) starting up the internal combustion engine by the controller,

7. A control ler for a hybrid vehicle, the h ybrid vehicle incl uding an internal combustion engine, an electric power output device and a controller, the internal combustion engine including a variable valve actuating device, the variable valve actuating device being configured to change an operation characteristic of an intake valve, the electric power output device being configured to output electric power to a device outside the vehicle, the electric power being generated by using the internal combustion engine, the controller comprising:

a valve actuation control unit configured to set at least one of a valve lift of the intake valve and a valve operating angle of the intake valve at start-up of the internal combustion engine such that the at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is output by the electric power output device to the device outside the vehicle is smaller than the corresponding at least one of the valve lift of the intake valve and the valve operating angle of the intake valve when electric power is not output by the electric power output device to the device outside the vehicle; and

a HV control unit configured to start up the internal combustion engine when electric power is output by the electric power output device to the device outside the vehicle.

8. The controller according to claim 7, wherein

the variable valve actuating device is configured to change the operation characteristic of the intake valve to one of a first characteristic and a second characteristic, at least one of the valve lift and the valve operating angle in the second characteristic is larger than the corresponding at least one of the valve lift and the valve operating angle in the first characteristic, and

when the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the valve actuation control unit is configured to set the operation characteristic of the intake valve to the first characteristic and then the HV control unit is configured to start up the internal combustion engine.

9. The controller according to claim 7, wherein

when the internal combustion engine is started up at the time when electric power is output by the electric power output device to the device outside the vehicle, the valve actuation control unit is configured to set the operation characteristic of the intake valve to the first characteristic, and then the HV control unit is configured to start up the internal combustion engi ne.

10. The controller according to any one of clai ms 7 to 9, wherein

the internal combustion engine includes a circulation device,

the circulation device is configu red to circulate exhaust gas from the internal combustion engine to an intake side of the internal combustion engine,

the HV control unit is configured to start circu lation of exhaust gas after start-up of the internal combustion engine, and

the HV control unit is configured to start the circulat ion of exhaust gas earlier when electric power is output by the electric power output device to the device outside the vehicle than when electric power is not output by the electric power output device to the device outside the vehicle.

11. The control ler according to any one of claims 7 to 10, the hybrid vehicle further including an electrical storage device configu red to store electric power generated by using the internal combustion engine, the controller further comprising:

a SOC calculation unit configured to calculate a state quality of the electrical storage device, the state quantity is a value indicating a state of charge of the electrical storage device wherein

the HV control unit is configured to start up the internal combustion engine when a state quantity of the electrical storage device is lower than a predetermined threshold, and the SOC calculation unit is configured to set the threshold such that the threshold at the time when electric power is output by the electric power output device to the device outside the vehicle is lower than the threshold at the time when electric power is not output by the electric^'power output device to the device outside the vehicle.