JP2016150720A - Hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce time during which rotation speed of an engine remains within a resonance band when lock abnormality of a planetary gear mechanism occurs.SOLUTION: An engine is configured so that opening/closing timing of an intake valve can be changed. An ECU, when abnormality occurs to at least either one of a first MG and a planetary gear mechanism, executes evacuation travel in which a vehicle travels using torque from a second MG without combusting the engine. The ECU, when rotation speed Ne of the engine is within a resonance band in which the rotation speed Ne of the engine resonates a power transmission system in the evacuation travel, shifts the opening/closing timing to an advance side if accelerator aperture Acc exceeds a predetermined reference value A0 in comparison with a case where the rotation speed Ne of the engine is not within the resonance band, and shifts the opening/closing timing to a retard side if the accelerator aperture Acc falls below the reference value A0.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a hybrid vehicle, and more particularly to a hybrid vehicle including an internal combustion engine configured to be able to change the opening / closing timing of an intake valve.

  An engine, a first motor generator (MG), a planetary gear mechanism that transmits torque from the engine and the first MG to the drive shaft, and a second MG that can output torque to the drive shaft without passing through the planetary gear mechanism Hybrid vehicles equipped with are commercially available. In the hybrid vehicle having such a configuration, an abnormality (lock abnormality) may occur in which the rotation of the sun gear included in the planetary gear mechanism is fixed and the first MG cannot be rotated. If reverse running is performed when there is a lock abnormality, the engine may reversely rotate. Therefore, for example, in the hybrid vehicle disclosed in Japanese Patent Application Laid-Open No. 2012-140061 (Patent Document 1), reverse running is prohibited when the first MG lock abnormality occurs (see paragraph [0008] of Patent Document 1). .

  It is also known that resonance occurs when the frequency of an engine power transmission system including a crankshaft, a torsional damper, and the like matches the natural frequency. When resonance occurs, the vibration of the power transmission system is transmitted to the passenger compartment or abnormal noise is generated from the power transmission system, which may impair comfort.

JP 2012-140061 A

  In addition to the above-described first MG lock abnormality, a lock abnormality may occur in which the relative rotation of each gear included in the planetary gear mechanism is disabled. When these planetary gear mechanisms lock abnormally, power generation and discharge using the first MG cannot be performed as normal. Therefore, when a lock abnormality occurs, it is conceivable to perform EV travel using torque from the second MG without burning the engine as retreat travel.

  The power transmission system can also resonate when this evacuation travel is executed. In order to avoid the occurrence of vibration or abnormal noise due to resonance for a long time, it is desirable to make the time during which the engine rotation speed stays in the resonance band as short as possible. However, under the constraint that the planetary gear mechanism is locked abnormally and the engine is not combusted, the engine rotation speed is determined according to the vehicle speed, and therefore it is difficult to appropriately adjust the engine rotation speed. As a result, there is a possibility that the time during which the engine rotation speed stays in the resonance band becomes long.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to shorten the time during which the engine rotation speed stays in the resonance band when a planetary gear mechanism lock abnormality occurs. is there.

  A hybrid vehicle according to an aspect of the present invention includes an internal combustion engine, first and second rotating electrical machines, a planetary gear mechanism, and a control device that controls the internal combustion engine and the first and second rotating electrical machines. The internal combustion engine is configured to be able to change the opening / closing timing of the intake valve. The first rotating electrical machine has a rotating shaft connected to the output shaft of the internal combustion engine. The second rotating electrical machine outputs torque to the drive shaft of the hybrid vehicle. The planetary gear mechanism includes a carrier coupled to the output shaft of the internal combustion engine, a sun gear coupled to the rotational shaft of the first rotating electrical machine, and a ring gear coupled to the rotational shaft of the second rotating electrical machine. When at least one of an abnormality in which the rotation of the sun gear is suppressed or an abnormality in which the relative rotation of the carrier, the sun gear, and the ring gear is suppressed occurs, the control device does not burn the internal combustion engine and The evacuation traveling that travels using the torque of is executed. When the rotational speed of the internal combustion engine is within a resonance band that resonates the output shaft during retreat travel, the control device determines that the accelerator opening is a predetermined reference value compared to when the rotational speed of the internal combustion engine is not within the resonance band. When the value exceeds the opening / closing timing, the opening / closing timing is changed to the advance side, and when the accelerator opening is lower than the reference value, the opening / closing timing is changed to the retard side.

  If the opening / closing timing of the intake valve is changed to the advance side when the accelerator opening exceeds the reference value, the friction of the internal combustion engine is reduced. As a result, the rotational speed of the internal combustion engine is likely to increase, so that it is easy to realize a state where the rotational speed of the internal combustion engine exceeds the upper limit value of the resonance band. Conversely, if the opening / closing timing is changed to the retarded side when the accelerator opening is below the reference value, the friction of the internal combustion engine increases. As a result, the rotational speed of the internal combustion engine is likely to decrease, so that it is easy to realize a state where the rotational speed of the internal combustion engine is below the lower limit value of the resonance band. Thus, according to the above configuration, by increasing or decreasing the rotational speed of the internal combustion engine in an appropriate direction according to the accelerator opening (that is, the user's accelerator operation), the rotational speed of the internal combustion engine falls within the resonance band. The residence time can be shortened.

  Preferably, the internal combustion engine is further configured to be able to change the opening / closing timing of the exhaust valve. The control device changes the opening / closing timing of the exhaust valve to the advance side when the reverse rotation of the internal combustion engine occurs during the retreat travel, compared to when the reverse rotation of the internal combustion engine does not occur.

  When the opening / closing timing of the exhaust valve is changed to the advance side during the reverse rotation of the internal combustion engine, the friction of the internal combustion engine increases as in the case where the opening / closing timing of the intake valve is changed to the retard side during the forward rotation of the internal combustion engine. . Therefore, according to the above configuration, when reverse rotation of the internal combustion engine occurs, the reverse rotation can be stopped early by increasing the friction of the internal combustion engine.

  According to the present invention, when a planetary gear mechanism lock abnormality occurs, the time during which the engine rotation speed stays in the resonance band can be shortened.

1 is a block diagram schematically showing an overall configuration of a hybrid vehicle according to a first embodiment. It is a figure which shows the detailed structure of an engine. It is a figure which shows an example of control of the opening / closing timing of an intake valve. It is a collinear diagram for demonstrating evacuation travel at the time of MG1 lock | rock abnormality generation | occurrence | production. It is an alignment chart for explaining retreat travel when a planetary lock abnormality occurs. It is a figure for demonstrating the advance angle control of an intake valve. It is a figure for demonstrating the retard angle control of an intake valve. 4 is a flowchart for illustrating control of intake valve opening and closing timing in the first embodiment. It is an alignment chart for explaining engine reverse rotation when MG1 lock abnormality occurs. It is an alignment chart for explaining engine reverse rotation when a planetary lock abnormality occurs. It is a figure for demonstrating the advance angle control of an exhaust valve. 6 is a flowchart for illustrating control of opening and closing timings of an intake valve and an exhaust valve in the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
<Overall configuration of hybrid vehicle>
FIG. 1 is a block diagram schematically showing the overall configuration of the hybrid vehicle according to the present embodiment. Referring to FIG. 1, vehicle 1 includes an engine 100, a power transmission system 110, a first motor generator (MG) 10, a planetary gear mechanism 250, a planetary lock mechanism 260, a second MG 20, A drive wheel 350, a power control unit (PCU) 200, a system main relay (SMR) 160, a battery 150, and an electronic control unit (ECU) 300 are provided.

  Engine 100 includes an internal combustion engine such as a gasoline engine or a diesel engine. When engine 100 is started by cranking of first MG 10, power is supplied to at least one of drive wheel 350 and first MG 10 via planetary gear mechanism 250.

  The engine 100 is provided with an electric VVT mechanism 105 for changing the opening / closing timing of the intake valve 410. The electric VVT mechanism 105 is controlled by the ECU 300 according to the traveling state of the vehicle 1, the startability of the engine 100, emissions, and the like. The configurations of engine 100 and electric VVT mechanism 105 will be described in detail with reference to FIGS. 2 and 3.

  The power transmission system 110 includes a crankshaft (output shaft) 112 and a torsional damper 114. The torsional damper 114 is provided on a pulley (not shown) of the crankshaft 112 and absorbs torsional vibration of the crankshaft 112 due to torque fluctuations of the engine 100.

  Each of first MG 10 and second MG 20 is an AC rotating electric machine, for example, a three-phase AC permanent magnet type synchronous motor. First MG 10 can generate power using the power of engine 100 received via planetary gear mechanism 250. For example, when the SOC (State Of Charge) of battery 150 reaches a predetermined lower limit, engine 100 is started and power is generated by first MG 10. The electric power generated by the first MG 10 is voltage-converted by the PCU 200 and stored in the battery 150 or directly supplied to the second MG 20.

  Second MG 20 generates driving force using at least one of the electric power stored in battery 150 and the electric power generated by first MG 10. The driving force of the second MG 20 is applied to the driving wheel 350 via the propeller shaft 650.

  Planetary gear mechanism 250 divides the power generated by engine 100 into power for driving drive wheels 350 and power for driving first MG 10. Specifically, the planetary gear mechanism 250 includes a sun gear S, a ring gear R, a pinion gear P, and a carrier C. The sun gear S is connected to the rotor (rotary shaft) 610 of the first MG 10. Ring gear R is coupled to rotor (rotating shaft) 620 of second MG 20. The pinion gear P meshes with the sun gear S and the ring gear R. The carrier C holds the pinion gear P so that the pinion gear P can rotate and revolve, and is connected to the crankshaft 112 of the engine 100.

  Planetary lock mechanism 260 is provided between carrier C and sun gear S, and includes a clutch and an actuator (not shown). Planetary lock mechanism 260 fixes the sun gear (ie, rotor 610 of first MG 10) using frictional force in accordance with control by ECU 300. Planetary lock mechanism 260 switches between a state in which carrier C and sun gear S are disconnected and a state in which carrier C and sun gear S are engaged. That is, the planetary lock mechanism 260 switches between a state in which relative rotation of the carrier C, the sun gear S, and the ring gear R is allowed and a state in which the relative rotation is suppressed (fixed).

  PCU 200 is a drive device for driving first MG 10 and second MG 20 based on a control signal from ECU 300. PCU 200 includes an inverter (not shown) for converting a voltage between battery 150 and first MG 10 and second MG 20. PCU 200 may further include a converter (not shown) for boosting or stepping down a DC voltage between battery 150 and the inverter.

  SMR 160 is electrically connected between PCU 200 and battery 150. SMR 160 switches between power supply and cutoff between PCU 200 and battery 150 based on a control signal from ECU 300.

  The battery 150 is a rechargeable DC power source, and includes a secondary battery such as a nickel metal hydride battery or a lithium ion battery, or a capacitor such as an electric double layer capacitor.

  Although not shown, ECU 300 includes a CPU (Central Processing Unit), a storage device, an input / output buffer, and the like. ECU 300 controls each device by outputting a control signal based on input signals from various sensors. Specifically, signals from the engine speed sensor 102, the resolvers 12 and 22, the vehicle speed sensor 652, and the accelerator opening sensor 510 are input to the ECU 300.

  The engine rotation speed sensor 102 detects the rotation speed (engine rotation speed) Ne of the engine 100. The resolver 12 detects the rotational speed (MG1 rotational speed) Nm1 of the first MG 10. The resolver 22 detects the rotation speed (MG2 rotation speed) Nm2 of the second MG 20. The vehicle speed sensor 652 detects the rotation speed (propeller shaft rotation speed) Np of the propeller shaft 650. Each sensor outputs the detection result to ECU 300. ECU 300 controls the hybrid system (engine 100, first MG 10 and second MG 20) of vehicle 1 based on the detection results of the sensors. ECU 300 calculates vehicle speed V from propeller shaft rotation speed Np.

  Accelerator opening sensor 510 detects accelerator opening Acc corresponding to the amount of depression of an accelerator pedal (not shown) by the user, and outputs the detection result to ECU 300. ECU 300 calculates torque (required torque) to be output to drive wheels 350 based on accelerator opening Acc and vehicle speed V, and sets a required drive force to vehicle 1 corresponding to the required torque.

<Engine configuration>
FIG. 2 is a diagram illustrating a detailed configuration of the engine 100. Referring to FIG. 2, the intake air amount to engine 100 is adjusted by a throttle valve 404 using a throttle motor 402 as a drive source. Throttle opening sensor 406 detects throttle opening θth and outputs the detection result to ECU 300.

  The injector 408 injects fuel into the intake port. The air-fuel mixture in which fuel and air are mixed at the intake port is introduced into the cylinder 430 when the intake valve 410 is opened. The air-fuel mixture in the cylinder 430 is ignited by the spark plug 432 and burned. The piston 440 is pushed down by the combustion of the air-fuel mixture, and the crankshaft 112 rotates. The combusted air-fuel mixture (exhaust gas) is purified by the catalysts 452 and 454 provided in the exhaust passage 450 and then discharged outside the vehicle.

  At the top of the cylinder 430 (cylinder head), an intake valve 410 for adjusting the amount and timing of air introduced into the cylinder 430 and the amount and timing of exhaust gas discharged from the cylinder 430 are adjusted. An exhaust valve 420 is provided. Opening and closing of intake valve 410 and exhaust valve 420 is controlled by electric VVT mechanism 105. The electric VVT mechanism 105 includes an intake camshaft 412, an exhaust camshaft 422, a cam sprocket (not shown), and an electric actuator 460. The electric actuator 460 may be a motor or a solenoid.

  Each of the intake side camshaft 412 and the exhaust side camshaft 422 is provided in the cylinder head such that the direction of the rotation axis thereof is parallel to the axial direction of the crankshaft 112. A plurality of cams 414 (only one is shown in FIG. 2) are fixed to the intake side camshaft 412 at a predetermined interval. When the intake camshaft 412 rotates, the intake valve 410 provided in each cylinder is opened and closed by the cam 414. Similarly, when the exhaust side camshaft 422 rotates, the exhaust valve 420 provided in each cylinder is opened and closed by the cam 424.

  The cam sprocket is provided at one end of each of the intake side camshaft 412 and the exhaust side camshaft 422. The same timing chain (not shown) is wound around each cam sprocket. This timing chain is also wound around a timing rotor (not shown) provided on the crankshaft 112. Therefore, the intake side camshaft 412, the exhaust side camshaft 422, and the crankshaft 112 rotate in synchronization with the timing chain.

  The cam angle sensor 476 detects the position of the cam 414 provided on the intake side camshaft 412 and the position of the cam 424 provided on the exhaust side camshaft 422, and outputs the detection result to the ECU 300. The crank angle sensor 478 detects the rotational speed (= engine rotational speed Ne) of the crankshaft 112 and the rotational angle (crank angle) CA of the crankshaft 112, and outputs the detection result to the ECU 300.

  ECU 300 changes the opening / closing timing of intake valve 410 by executing feedback control of electric actuator 460 based on the detection results by cam angle sensor 476 and crank angle sensor 478.

  FIG. 3 is a diagram illustrating an example of control of the opening / closing timing of the intake valve 410. The vertical axis in FIG. 3 represents the valve displacement amount of the intake valve 410, and the horizontal axis represents the crank angle CA.

  2 and 3, as shown by waveform EX, exhaust valve 420 opens as crank angle CA increases, and exhaust valve 420 closes after the valve displacement amount of exhaust valve 420 reaches a peak. Thereafter, as indicated by the waveform IN1, the intake valve 410 is opened, and the intake valve 410 is closed after the valve displacement amount of the intake valve 410 reaches a peak.

  The “valve displacement amount” of the intake valve 410 means the displacement amount of the intake valve 410 from the state in which the intake valve 410 is closed. A valve displacement amount when the opening degree of the intake valve 410 reaches a peak is referred to as “lift amount”, and a crank angle from when the intake valve 410 is opened until it is closed is referred to as “working angle”.

  In the present embodiment, electric VVT mechanism 105 uses electric actuator 460 to change the opening / closing timing of intake valve 410 while maintaining the lift amount and operating angle of intake valve 410. That is, the electric VVT mechanism 105 changes the opening / closing timing of the intake valve 410 while maintaining the waveform shape between the waveform IN1 and the waveform IN2. Intake when the crank angle CA (0) changes the valve displacement amount with the waveform IN1 and corresponds to the opening timing of the intake valve 410 when the crank angle CA (0) changes the valve displacement amount with the waveform IN2. This corresponds to the opening timing of the valve 410.

  Changing the opening / closing timing from the crank angle CA (0) to the crank angle CA (1) is referred to as “retarding” the opening / closing timing. Conversely, changing the opening / closing timing from the crank angle CA (1) to the crank angle CA (0) is referred to as “advancing” the opening / closing timing. In the present embodiment, the crank angle CA (0) is the most advanced valve opening timing, and the crank angle CA (1) is the most retarded valve opening timing.

  Although the first embodiment describes a configuration in which only the opening / closing timing of the intake valve 410 can be changed, the opening / closing timing of both the intake valve 410 and the exhaust valve 420 may be changeable. The electric VVT mechanism 105 may be configured such that one or both of the lift amount and the operating angle can be changed in addition to the opening / closing timing. It is not essential that the VVT mechanism is electric, and it may be hydraulic.

<Resonance of power transmission system>
In general, it is known that torsional vibrations occur in the crankshaft due to engine torque fluctuations. As described with reference to FIG. 1, torsional vibration can be reduced to some extent by providing the torsional damper 114 on the crankshaft 112. However, when the frequency of the power transmission system 110 matches the natural frequency, the power transmission system 110 resonates. As a result, the vibration of the power transmission system 110 is transmitted to the vehicle interior, or abnormal noise (specifically, the gear rattling noise of the gear meshing with the crankshaft 112) is generated from the power transmission system 110. It may be damaged. Although the resonance band of the power transmission system 110 varies depending on the vehicle type, in many cases, the resonance band exists in a relatively low band of the engine rotation speed Ne (for example, a band near 200 rpm). In order to avoid the occurrence of vibration or abnormal noise for a long time, it is desirable to make the time during which the engine rotation speed stays in the resonance band as short as possible.

<Evacuation>
In the planetary lock mechanism 260, for example, when a misengagement occurs, an abnormality that may occur when the rotor 610 of the MG 10 is fixed may occur. Further, an abnormality may occur in which the carrier C, the sun gear S and the sun gear S are solidified and the carrier C, the sun gear S, and the ring gear R rotate integrally. In the present specification, these abnormalities are referred to as “MG1 lock abnormality” and “planetary lock abnormality”, respectively.

  When these abnormalities occur, power generation and discharge using the first MG 10 cannot be performed as in normal times. Therefore, when the MG1 lock abnormality or the planetary lock abnormality occurs, the EV travel using the torque (MG2 torque) from the second MG 20 is performed as the retreat travel without burning the engine 100.

  FIG. 4 is a collinear diagram for explaining retreat travel when an MG1 lock abnormality occurs. FIG. 5 is a collinear diagram for explaining retreat travel when a planetary lock abnormality occurs.

  Referring to FIG. 4, planetary gear mechanism 250 is configured as described in FIG. 1, so that MG1 rotation speed Nm1 (= rotation speed of sun gear S) and engine rotation speed Ne (= rotation of carrier C). Speed) and the MG2 rotational speed Nm2 (= the rotational speed of the ring gear R) have a relationship of being connected by a straight line on the alignment chart. That is, if the rotational speed of any two components is determined, the rotational speeds of the remaining components are also determined.

  When the MG1 lock abnormality occurs, the MG1 rotation speed Nm1 is fixed to zero. Since MG2 rotational speed Nm2 is equal to propeller shaft rotational speed Np, it changes according to vehicle speed V. Therefore, the engine rotation speed Ne changes according to the vehicle speed V in accordance with the above relationship.

  A straight line L11 represents a state where the engine rotation speed Ne is within the resonance band. When the engine rotation speed Ne is within the resonance band, the engine rotation speed Ne is increased so as to exceed the upper limit value of the resonance band as shown by the straight line L12, or the lower limit value of the resonance band is shown by the straight line L13. It is desirable to reduce the engine rotational speed Ne so as to be less than.

  Referring to FIG. 5, when a planetary lock abnormality occurs, MG1 rotational speed Nm1, engine rotational speed Ne, and MG2 rotational speed Nm2 become substantially equal to each other. Also in this case, the engine rotation speed Ne changes according to the vehicle speed V. The straight lines L21 to L23 correspond to the straight lines L11 to L13 shown in FIG.

  As described above, under the restriction that the MG1 lock abnormality or the planetary lock abnormality occurs and the engine 100 is not combusted, the engine rotation speed Ne is determined according to the vehicle speed V. Therefore, by adjusting the vehicle speed V using the second MG 20, the engine rotational speed Ne is adjusted so as to deviate from the resonance band (set larger than the upper limit value of the resonance band or smaller than the lower limit value of the resonance band). It will be.

  When the discharge power from the battery 150 (so-called discharge power upper limit Wout) has a certain margin, sufficient power can be supplied from the battery 150 to the second MG 20. Therefore, it is considered that by increasing the vehicle speed V by acceleration using the MG2 torque, it is possible to quickly increase the engine rotational speed Ne above the upper limit value of the resonance band. Further, when there is a margin in the charging power to battery 150 (so-called charging power upper limit value Win), power generated by regenerative braking of second MG 20 can be charged to battery 150. Therefore, it is considered that the engine rotational speed Ne can be quickly reduced below the lower limit value of the resonance band by reducing the vehicle speed V by regenerative braking.

  However, depending on how the vehicle 1 is used (in a high temperature or extremely low temperature environment, or in a high SOC or low SOC), the charge / discharge power of the battery 150 is severely limited, and the time required to change the vehicle speed V becomes long. obtain. As a result, there is a possibility that the time during which the engine rotation speed Ne stays in the resonance band becomes long.

  Therefore, according to the present embodiment, the opening / closing timing of the intake valve 410 is advanced when the engine speed Ne is within the resonance band in the retreat travel, compared to when the engine speed Ne is not within the resonance band. A configuration is adopted in which the engine rotational speed Ne is assisted to be easily deviated from the resonance band by changing to the side or the retard side. The changing direction of the opening / closing timing is determined based on the accelerator opening Acc. That is, when the accelerator opening Acc exceeds the predetermined reference value A0, the ECU 300 executes “advance control” that changes the opening / closing timing of the intake valve 410 to the advance side, and the accelerator opening Acc becomes equal to the reference value A0. When it falls below, “retard angle control” for changing the opening / closing timing to the retard side is executed.

<Advance control and retard control>
Hereinafter, the advance angle control and the retard angle control of the intake valve 410 will be described in order. Again, since both the advance angle control and the retard angle control are executed during the retreat travel, no fuel is supplied to the engine 100 and no fuel is burned.

  FIG. 6 is a diagram for explaining the advance angle control of the intake valve 410. FIG. 7 is a diagram for explaining the retard angle control of the intake valve 410. 6 and 7, the valve opening timing of the intake valve 410 is expressed as “IVO (Intake Valve Opening)”, and the valve closing timing of the intake valve 410 is expressed as “IVC (Intake Valve Closing)”. The opening timing of the exhaust valve 420 is expressed as “EVO (Exhaust Valve Opening)”, and the closing timing of the exhaust valve 420 is expressed as “EVC (Exhaust Valve Closing)”. The top dead center timing is represented as “TDC (Top Dead Center)”, and the bottom dead center timing is represented as “BDC (Bottom Dead Center)”.

  Referring to FIGS. 2 and 6, when the advance angle control of intake valve 410 is executed, the intake valve 410 is opened more than when the advance angle control is not executed (when the engine speed Ne is not within the resonance band). The valve timing IVO is accelerated. Therefore, when the piston 440 moves from the TDC toward the BDC, the suction speed (the suction amount per unit time) of the air sucked into the cylinder 430 increases. That is, since the piston 440 is pushed down with a relatively large amount of air present in the cylinder 430, the pumping loss in the intake stroke is reduced. Hereinafter, this is also expressed as “the friction is reduced” of the engine 100.

  On the other hand, referring to FIG. 2 and FIG. 7, when the retard control of the intake valve 410 is executed, the valve opening timing IVO of the intake valve 410 is delayed as compared with the case where the retard control is not executed. Therefore, when the piston 440 starts moving from the TDC toward the BDC, the inside of the cylinder 430 becomes a state close to a vacuum, so that the pumping loss in the intake stroke increases. Hereinafter, this is also expressed as “the friction increases” of the engine 100.

  As described above, when the advance angle control of the intake valve 410 is executed when the vehicle 1 is accelerated, the friction of the engine 100 is reduced, and the engine rotation speed Ne is likely to increase. As a result, the engine rotation speed Ne easily exceeds the upper limit value of the resonance band (see the straight line L12 in FIG. 4 and the straight line L22 in FIG. 5). On the contrary, if the retard control of the intake valve 410 is executed when the vehicle 1 is decelerated (or coasting), the friction of the engine 100 increases, so the engine speed Ne tends to decrease. As a result, the engine rotation speed Ne is likely to fall below the lower limit value of the resonance band (see the straight line L13 in FIG. 4 and the straight line L23 in FIG. 5). Therefore, the time during which the engine speed Ne stays in the resonance band can be shortened.

  FIG. 8 is a flowchart for explaining the control of the opening / closing timing of intake valve 410 in the first embodiment. The flowchart shown in FIG. 8 and FIG. 11 described later is called from the main routine and executed when a predetermined condition is satisfied or every predetermined period. Each step of the flowchart is basically realized by software processing by the ECU 300, but may be realized by hardware (electronic circuit) manufactured in the ECU 300.

  In S10, ECU 300 determines whether an MG1 lock abnormality has occurred. Specifically, ECU 300 controls PCU 200 to output torque (MG1 torque) from first MG 10. Based on the detection result from resolver 12, ECU 300 determines that MG1 lock abnormality has occurred when the amount of change in MG1 rotational speed Nm1 is less than a predetermined value, and the amount of change in MG1 rotational speed Nm1 is a predetermined value. In the above case, it is determined that no MG1 lock abnormality has occurred.

  If MG1 lock abnormality has not occurred (NO in S10), ECU 300 advances the process to S20 and further determines whether or not planetary lock abnormality has occurred. Specifically, ECU 300 determines that engine rotational speed Ne, MG1 rotational speed Nm1, and MG2 rotational speed Nm2 are substantially equal to each other based on detection results from engine rotational speed sensor 102 and resolvers 12 and 22. When it continues, it determines with the planetary lock abnormality having arisen, and when the said state does not continue, it determines with the planetary lock abnormality having not occurred.

  If an MG1 lock abnormality has occurred (YES in S10), or if a planetary lock abnormality has occurred (YES in S20), ECU 300 advances the process to S30 and executes the retreat travel. Specifically, ECU 300 executes EV traveling using MG2 torque without burning engine 100. Furthermore, ECU 300 prohibits reverse travel in order to prevent reverse rotation of engine 100 (S40).

  If neither MG1 lock abnormality nor planetary lock abnormality has occurred (NO in S20), the need for executing retreat travel is low, and ECU 300 returns the process to the main routine.

  In S50, the ECU 300 determines whether or not the engine rotation speed Ne is within the resonance band. When engine speed Ne is within the resonance band (YES in S50), resonance of power transmission system 110 may occur. Therefore, ECU 300 determines whether or not accelerator opening Acc is larger than reference value A0 (S60). As reference value A0, it is preferable to use a minimum value at which actual accelerator opening Acc> 0 in consideration of detection error of accelerator opening sensor 510 (for example, variations in sensor characteristics).

  When accelerator opening Acc is larger than reference value A0 (YES in S60), that is, when the user is accelerating vehicle 1 by the accelerator operation, ECU 300 executes advance angle control (S70). As a result, the friction of the engine 100 is reduced, and the engine rotation speed Ne is likely to increase rapidly, so that the engine rotation speed Ne easily exceeds the upper limit value of the resonance band.

  On the other hand, when accelerator opening Acc is equal to or smaller than reference value A0 (NO in S60), that is, when the user is trying to stop vehicle 1 or to run with inertia, ECU 300 performs retard control of intake valve 410. Execute (S80). As a result, the friction of the engine 100 increases and the engine rotational speed Ne tends to decrease rapidly, so that the engine rotational speed Ne easily falls below the lower limit value of the resonance band.

  When the process of S70 or S80 ends, ECU 300 returns the process to the main routine. If engine speed Ne is not within the resonance band (NO in S50), resonance of power transmission system 110 is unlikely to occur, and ECU 300 returns the process to the main routine.

  As described above, according to the first embodiment, when the MG1 lock abnormality or the planetary lock abnormality occurs, the friction of the engine 100 can be adjusted by controlling the valve opening timing IVO of the intake valve 410. Whether to increase or decrease the friction of engine 100 is determined based on accelerator opening Acc (that is, acceleration operation by the user). When the vehicle 1 is accelerated, the engine rotation speed Ne easily exceeds the upper limit value of the resonance band by reducing the friction of the engine 100 by the advance angle control. On the other hand, when the vehicle 1 is not accelerated, the engine rotation speed Ne is likely to fall below the lower limit value of the resonance band by increasing the friction of the engine 100 by retard control. Therefore, the time during which the engine speed Ne stays in the resonance band can be shortened.

[Embodiment 2]
During execution of the above-described evacuation traveling, for example, when the traveling of a vehicle stopped on an uphill road is resumed, the vehicle may retreat and the engine may reversely rotate. In the second embodiment, description will be given of a configuration in which a reverse-rotating engine is stopped early by using a VVT mechanism.

  The hybrid vehicle according to the second embodiment includes a vehicle 1 according to the first embodiment (see FIGS. 1 and 2) in that the hybrid vehicle includes an engine configured to be able to change the opening / closing timing of both the intake valve 410 and the exhaust valve 420. ) Is different. Since the other configuration of the hybrid vehicle according to the second embodiment is the same as the configuration of vehicle 1, description thereof will not be repeated.

  FIG. 9 is a collinear diagram for illustrating reverse rotation of engine 100 when an MG1 lock abnormality occurs. FIG. 10 is a collinear diagram for illustrating reverse rotation of engine 100 when a planetary lock abnormality occurs.

  Referring to FIGS. 9 and 10, when vehicle 1 is executing retreat traveling, vehicle 1 may slightly move backward (slip down) when resuming traveling from a state where it has stopped on an uphill road. is there. In particular, when the user depresses the accelerator pedal instead of the brake pedal, and the MG2 torque generated thereby maintains the stop state of the vehicle 1 (when the so-called accelerator hold is executed), such a situation occurs. Prone to occur. When the vehicle 1 slides down, the propeller shaft rotational speed Np becomes negative and the engine rotational speed Ne becomes negative as shown by straight lines L31 and L41. That is, reverse rotation of engine 100 may occur.

  Therefore, according to the second embodiment, the exhaust valve 420 is advanced when the vehicle retreats during retreat travel (when the engine 100 rotates reversely) compared to when the engine 100 does not rotate reversely. Execute control. In the second embodiment, this control is referred to as advance angle control of the exhaust valve 420. The reverse rotation of the engine 100 can be stopped early by the advance angle control of the exhaust valve 420 (see straight lines L32 and L42).

  FIG. 11 is a view for explaining the advance angle control of the exhaust valve 420. When FIG. 11 is compared with FIG. 6 or FIG. 7, the direction of each arrow indicating the opening / closing timing of the intake valve 410 and the exhaust valve 420 is reversed due to the reverse rotation of the engine 100.

  When the advance angle control of the exhaust valve 420 is executed, the valve closing timing EVC of the exhaust valve 420 is advanced compared to the case where the advance angle control is not executed. Therefore, when the piston 440 moves from TDC toward BDC (between TDC and EVC), the inside of the cylinder 430 is in a state close to vacuum. As a result, the amount of work required to push down the piston 440 increases, and the pumping loss increases. That is, the friction of the engine 100 increases. Therefore, further reduction in engine rotation speed Ne can be suppressed and reverse rotation of engine 100 can be stopped early.

  FIG. 12 is a flowchart for explaining control of opening / closing timing of intake valve 410 and exhaust valve 420 in the second embodiment. Referring to FIG. 12, this flowchart differs from the flowchart of the first embodiment (see FIG. 8) in that it further includes the processes of S90 and S100. Since other processes are equivalent to the corresponding processes in the flowchart of the first embodiment, description thereof will not be repeated.

  In S50, the ECU 300 determines whether or not the engine rotation speed Ne is within the resonance band. If engine speed Ne is not within the resonance band (NO in S50), ECU 300 advances the process to S90 to determine whether propeller shaft speed Np is less than 0, that is, whether engine 100 is rotating in reverse. Is further determined. This determination can also be performed using the engine speed Ne.

  When propeller shaft rotation speed Np is less than 0, that is, when engine 100 is rotating in the reverse direction (YES in S92), ECU 300 executes the advance angle control of exhaust valve 420. Thereafter, ECU 300 returns the process to the main routine.

  On the other hand, when propeller shaft rotational speed Np is equal to or greater than 0 (NO in S52), that is, when engine 100 is stopped or rotating forward, ECU 300 does not execute the advance control of exhaust valve 420 and performs the process. Return to the main routine.

  As described above, according to the second embodiment, when engine 100 is rotating in the reverse direction, the advance angle control of exhaust valve 420 is executed to increase the friction of engine 100, so that the reverse rotation of engine 100 is performed. It can be stopped early. In the advance angle control of the exhaust valve 420, the advance amount is preferably set to a maximum value (maximum advance value). This is because the friction of the engine 100 becomes the largest, and the effect of stopping the reverse rotation of the engine rotation speed Ne becomes the highest.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Vehicle, 10 1st MG (Motor Generator), 20 2nd MG, 12, 22 Resolver, 100 Engine, 102 Engine rotational speed sensor, 105 Electric VVT (Variable Valve Timing) mechanism, 110 Power transmission system, 112 Crankshaft, 114 Toe National damper, 150 battery, 250 planetary gear mechanism, 260 planetary lock mechanism, 350 drive wheel, 402 throttle motor, 404 throttle valve, 406 throttle opening sensor, 408 injector, 410 intake valve, 412 intake camshaft, 414, 424 Cam, 420 exhaust valve, 422 exhaust side camshaft, 430 cylinder, 432 spark plug, 440 piston, 450 exhaust passage, 452, 454 catalyst, 460 electric actuator, 4 76 cam angle sensor, 478 crank angle sensor, 510 accelerator opening sensor, 610,620 rotor, 650 propeller shaft, 652 vehicle speed sensor, C carrier, P pinion gear, R ring gear, S sun gear.

Claims (2)

A hybrid vehicle,
An internal combustion engine configured to be able to change the opening and closing timing of the intake valve;
A first rotating electric machine having a rotating shaft coupled to an output shaft of the internal combustion engine;
A second rotating electrical machine that outputs torque to the drive shaft of the hybrid vehicle;
A planetary gear mechanism including a carrier coupled to the output shaft of the internal combustion engine, a sun gear coupled to the rotational shaft of the first rotating electrical machine, and a ring gear coupled to the rotational shaft of the second rotating electrical machine;
A control device for controlling the internal combustion engine and the first and second rotating electrical machines,
The controller is
If at least one of an abnormality that suppresses rotation of the sun gear or an abnormality that suppresses relative rotation of the carrier, the sun gear, and the ring gear occurs, the second rotation is performed without burning the internal combustion engine. Execute evacuation travel using the torque from the electric machine,
In the retreat travel, when the rotational speed of the internal combustion engine is within a resonance band that resonates the output shaft, the accelerator opening is a predetermined reference compared to when the rotational speed of the internal combustion engine is not within the resonance band. A hybrid vehicle that changes the opening / closing timing to an advance side when exceeding a value, and changes the opening / closing timing to a retard side when the accelerator opening is less than the reference value. The internal combustion engine is further configured to be able to change the opening and closing timing of the exhaust valve,
The control device changes the opening / closing timing of the exhaust valve to an advance side when the reverse rotation of the internal combustion engine occurs in the retreat travel, as compared with a case where the reverse rotation of the internal combustion engine does not occur. The hybrid vehicle according to claim 1.

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