JP2016132427A - Hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle enabling sufficient use of electric power in which a power storage device can output during EV traveling.SOLUTION: While maintaining a valve opening period of an intake valve, an engine 100 can change opening/closing timing by using a variable valve train. During EV traveling using only torque of a motor generator MG2, when required drive torque exceeds maximum torque of the motor generator MG2, a control device 200 operates the variable valve mechanism so as to advance the opening/closing timing of the intake valve of the engine 100, and allows an increase in the drive torque by using a motor generator MG1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to control of a hybrid vehicle including a power split device in which an engine, a rotating electrical machine, and drive wheels that are electrically changeable for opening the intake valve are connected.

  Conventionally, a hybrid vehicle includes an engine, a first motor generator, a planetary gear mechanism connected to the engine, the first motor generator, and drive wheels, and a second motor generator connected to the drive wheels. It is.

  As such a hybrid vehicle, for example, in Japanese Patent Application Laid-Open No. 2011-235694 (Patent Document 1), when the power generation torque is limited by the SOC (State Of Charge) of the battery, the rating of the motor generator, or the like, A technique for preventing over-rotation of the motor generator by limiting the output is disclosed.

JP 2011-235694 A

  However, in a hybrid vehicle, when MG1 outputs a negative torque during EV traveling, the engine may reversely rotate. Therefore, during EV traveling, the vehicle travels only with MG2 torque, and there is a problem that the electric power that can be output by the power storage device cannot be fully utilized.

  Therefore, an object of the present invention is to provide a hybrid vehicle that can sufficiently use the electric power that can be output by the power storage device during EV traveling.

  In summary, the present invention is a hybrid vehicle in which an opening / closing timing can be changed by a variable valve mechanism while maintaining a valve opening period of an intake valve, a first motor generator, a second motor generator, and an engine A power split device having three rotating elements respectively connected to the rotating shaft of the first motor generator, the rotating shaft of the first motor generator, and the rotating shaft of the second motor generator; and a drive wheel connected to the rotating shaft of the second motor generator; And a control device for controlling the engine, the first motor generator, and the second motor generator. The control device controls the variable valve so as to advance the opening / closing timing of the intake valve when the required drive torque exceeds the maximum torque of the second motor generator during EV travel using only the torque of the second motor generator. The mechanism is activated and then allowed to increase the drive torque using the first motor generator.

  During EV travel using only the torque of the second motor generator, the variable valve mechanism is operated so as to advance the opening / closing timing of the intake valve when the required drive torque exceeds the maximum torque of the second motor generator. As a result, engine friction increases. As a result, the engine can be prevented from rotating reversely even when torque is output from the first motor generator in order to increase the driving force.

  During EV travel, the power that can be output by the power storage device can be fully utilized.

It is the figure which showed the basic composition of the hybrid vehicle which concerns on embodiment. It is a figure which shows the structure of the engine shown by FIG. It is a figure which shows the relationship between the valve displacement amount and crank angle which are implement | achieved in an electric VVT apparatus. It is a figure for demonstrating the conventional EV performance. It is a nomographic chart for demonstrating the torque generation control in the conventional EV driving | running | working. It is an alignment chart for explaining torque generation control during EV traveling in the embodiment. It is a figure for demonstrating the relationship between the advance angle of the valve opening timing of an electric VVT apparatus, and the increase in engine friction. It is a flowchart which shows the procedure of EV traveling control by the control apparatus in 1st Embodiment. It is a flowchart which shows the procedure of EV travel control by the control apparatus in 2nd Embodiment. It is a flowchart which shows the procedure of EV travel control by the control apparatus in 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[First Embodiment]
As shown in FIG. 1, a hybrid vehicle (hereinafter simply referred to as a vehicle) 1 according to the present embodiment includes an engine 100, motor generators MG1 and MG2, a power split device 4, a speed reducer 5, and a drive. Wheel 6, power storage device 10, PCU (Power Control Unit) 20, and control device 200 are provided.

  Vehicle 1 can travel with a driving force output from at least one of engine 100 and motor generator MG2. The engine 100 is configured by an internal combustion engine such as a gasoline engine or a diesel engine, for example. Engine 100 supplies power to drive wheel 6 and / or motor generator MG1 operable as a generator via power split device 4.

  Engine 100 can be started by being cranked by motor generator MG1. This engine 100 has an electric VVT device 400 for changing the operation characteristic of the intake valve. The electric VVT device 400 is controlled by the control device 200 in accordance with the traveling state of the vehicle and the startability of the engine 100. The exhaust passage of the engine 100 is provided with an exhaust purification device that purifies the exhaust of the engine 100 using a catalyst. The engine 100, the electric VVT device 400, and the exhaust purification device will be described in detail later.

  Power split device 4 is configured to be able to split the driving force generated by engine 100 into power for driving drive wheels 6 via reduction gear 5 and power for driving motor generator MG1. Power split device 4 is constituted by a planetary gear mechanism, for example. In this case, for example, motor generator MG1 is connected to sun gear S of the planetary gear mechanism, engine 100 is connected to carrier C of the planetary gear mechanism, and motor generator MG2 and ring gear R of the planetary gear mechanism are connected. Drive wheels 6 are connected via a speed reducer 5.

  Motor generators MG1 and MG2 are AC rotating electric machines, for example, three-phase AC synchronous motor generators. Motor generators MG1 and MG2 can also operate as a generator and an electric motor.

  Motor generator MG <b> 1 can generate power using the power of engine 100 received via power split device 4. For example, when SOC (State Of Charge) of power storage device 10 reaches a predetermined lower limit, engine 100 is started and electric power is generated by motor generator MG1. The electric power generated by motor generator MG1 is voltage-converted by PCU 20, and is temporarily stored in power storage device 10, or directly supplied to motor generator MG2. Motor generator MG <b> 1 generates driving force using electric power stored in power storage device 10.

  Motor generator MG2 generates a driving force using at least one of the electric power stored in power storage device 10 and the electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to driving wheels 6 via reduction gear 5. In FIG. 1, the drive wheels 6 are shown as front wheels, but the rear wheels may be driven by the motor generator MG2 instead of the front wheels or together with the front wheels.

  During braking of the vehicle, motor generator MG2 is driven by drive wheels 6 via reduction gear 5, and motor generator MG2 operates as a generator. Thereby, motor generator MG2 operates as a regenerative brake that converts braking energy into electric power. The electric power generated by motor generator MG2 is stored in power storage device 10.

  PCU 20 is a drive device for driving motor generators MG1 and MG2. PCU 20 includes an inverter for driving motor generators MG <b> 1 and MG <b> 2, and may further include a converter for voltage conversion between the inverter and power storage device 10.

  The power storage device 10 is a rechargeable DC power source, and includes, for example, a secondary battery such as a nickel metal hydride battery or a lithium ion battery. The voltage of power storage device 10 is, for example, about 200V. Power storage device 10 stores electric power generated by motor generators MG1 and MG2. A large-capacity capacitor can also be employed as power storage device 10, and power storage device 10 temporarily stores the power generated by motor generators MG1 and MG2, and can supply the stored power to motor generator MG2. Anything can be used. In addition, the power storage device 10 is provided with a sensor for detecting the temperature, voltage, and current of the power storage device 10, and a value detected by the sensor is output to the control device 200.

  The control device 200 is configured to include an ECU (Electronic Control Unit) including a CPU (Central Processing Unit), a storage device, an input / output buffer, and the like (all not shown). The control device 200 inputs signals from various sensors (accelerator opening ACC, vehicle speed VSS, etc.) and outputs a control signal to each device, and controls each device in the hybrid vehicle 1. As a main thing, the control apparatus 200 performs control of the engine 100 (for example, electric VVT apparatus 400 etc.) according to driving control of the hybrid vehicle 1, and driving control. The operation of the control device 200 will be described later.

  Next, the configuration of engine 100 having electric VVT device 400 will be described. FIG. 2 is a diagram showing a configuration of engine 100 shown in FIG.

  Referring to FIG. 2, the intake air amount to engine 100 is adjusted by throttle valve 104 driven by throttle motor 312. The injector 108 injects fuel into the intake port. Fuel and air are mixed in the intake port. The air-fuel mixture is introduced into the cylinder 106 by opening the intake valve 118. The injector 108 may be provided as a direct injection injector that directly injects fuel into the cylinder 106. Alternatively, the injector 108 may be provided for both port injection and direct injection.

  The air-fuel mixture in the cylinder 106 is ignited by the spark plug 110 and burns. The air-fuel mixture after combustion, that is, exhaust gas, is discharged to the exhaust passage. The exhaust passage is provided with an exhaust purification device that purifies exhaust gas using a catalyst. The exhaust purification device includes a catalyst 112S (hereinafter also referred to as “S / C (startcat) catalyst”) and a catalyst 112U (hereinafter referred to as “U / F (under floor)) disposed downstream of the S / C catalyst 112S. And also referred to as “catalyst”). The exhaust gas is purified by the S / C catalyst 112S and the U / F catalyst 112U and then discharged outside the vehicle. The piston 114 is pushed down by the combustion of the air-fuel mixture, and the crankshaft 116 rotates.

  An intake valve 118 and an exhaust valve 120 are provided at the top of the cylinder 106. The amount and timing of the air introduced into the cylinder 106 is controlled by the intake valve 118. The amount and timing of the exhaust gas discharged from the cylinder 106 is controlled by the exhaust valve 120. The intake valve 118 is driven by a cam 122, and the exhaust valve 120 is driven by a cam 124.

  The operating characteristic of the intake valve 118 is changed by an electric VVT (Variable Valve Timing) device 400. Electric VVT device 400 includes a camshaft, a cam sprocket, and an electric actuator (all not shown). The camshaft is rotatably provided on the cylinder head of engine 100 such that the direction of the rotation axis is parallel to the rotation axis of the crankshaft. The camshaft includes an exhaust side camshaft that opens and closes an exhaust valve provided in each cylinder by a cam, and an intake side camshaft that opens and closes an intake valve provided in each cylinder by a cam. A plurality of cams 124 are fixed to the exhaust side camshaft at a predetermined interval. A plurality of cams 122 are fixed to the intake side camshaft at a predetermined interval.

  A cam sprocket is provided at one end of each of the intake and exhaust camshafts. The same timing chain is wound around both cam sprockets. The timing chain is also wound around a timing rotor (not shown) provided on the crankshaft 116. Therefore, the crankshaft and the camshaft rotate in synchronization with the timing chain.

  An electric actuator is provided between the camshaft and the cam sprocket. The electric actuator changes the rotational phase between the camshaft on the intake side and the cam sprocket. The operation of the electric actuator is controlled based on a control signal transmitted from the control device 200. When the rotational phase of the intake side camshaft and the cam sprocket is changed by the electric actuator, the intake valve 118 maintains the valve opening period, and the valve closing timing is linked to the valve opening timing and the valve opening timing. Will be changed.

  The manner in which the opening timing of the intake valve 118 by the electric VVT device 400 is changed will be described later. Electric VVT device 400 may change the valve opening timing of exhaust valve 120 instead of or in addition to intake valve 118.

  In addition to signals indicating the accelerator opening ACC and the vehicle speed VSS, the control device 200 receives signals from the cam angle sensor 300, the crank angle sensor 302, and the throttle opening sensor 306.

  The cam angle sensor 300 outputs a signal representing the cam position. The crank angle sensor 302 outputs a signal representing the rotation speed of the crankshaft 116 (engine rotation speed) and the rotation angle of the crankshaft 116. The throttle opening sensor 306 outputs a signal representing the throttle opening θth.

  Further, control device 200 controls engine 100 based on signals from these sensors. Specifically, the control device 200 controls the throttle opening θth, the ignition timing, and the fuel injection timing so that the engine 100 is operated at a desired operating point in accordance with the vehicle traveling state and the exhaust purification device warm-up state. The fuel injection amount and the operating state (opening / closing timing) of the intake valve 118 are controlled. The operating point is an operating point of the engine 100 at which the output, torque, and rotation speed of the engine 100 are determined. The operating point of the engine 100 is determined so that the engine 100 generates a desired output and torque. .

  Control device 200 sets a required output to engine 100 in the travel control of hybrid vehicle 1. Furthermore, the control device 200 controls the above parameter group so that the engine 100 operates at an operating point (combination of engine speed and engine torque) for generating the set required output.

  FIG. 3 is a diagram showing a relationship between the valve displacement amount and the crank angle realized in the electric VVT device 400. In FIG. 3, the vertical axis indicates the valve displacement, and the horizontal axis indicates the crank angle.

  As shown in FIG. 3, in the exhaust stroke, the exhaust valve 120 opens and closes after the displacement reaches a peak, and in the subsequent intake stroke, the intake valve 118 opens and closes after the displacement reaches a peak. The valve displacement amount of the exhaust valve 120 is shown in the waveform EX, while the valve displacement amount of the intake valve 118 is shown in the waveform IN.

  The valve displacement amount means a displacement amount of the intake valve 118 from a state where the intake valve 118 (or the exhaust valve 120) is closed. A valve displacement amount when the opening degree of the intake valve 118 reaches a peak is referred to as a lift amount, and a crank angle from when the intake valve 118 is opened until it is closed is referred to as a working angle.

  Electric VVT device 400 changes the valve opening timing and valve closing timing of intake valve 118 while maintaining the lift amount and operating angle. That is, the electric VVT device 400 changes the valve opening timing while maintaining the waveform between the solid line waveform and the broken line waveform of the waveform IN. In the present embodiment, the crank angle CA (0) corresponds to the opening timing of the intake valve 118 when the valve displacement is changed with the waveform IN (solid line), and the crank angle CA (1) has the waveform IN (dashed line). ) Corresponds to the opening timing of the intake valve 118 when the valve displacement is changed.

  In the following description, changing the valve opening timing in the direction from the crank angle CA (0) to the crank angle CA (1) is referred to as “retarding” the valve opening timing, and from the crank angle CA (1) to the crank angle. Changing the valve opening timing in the direction toward CA (0) is referred to as “advancing” the valve opening timing. Since the valve opening period is maintained, when the valve opening timing is “retarded”, the valve closing timing is also “retarded”. Since the valve opening period is maintained, when the valve opening timing is “advanced”, the valve closing timing is also “advanced” in conjunction. 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.

  In the present embodiment, the waveform IN (solid line) of the valve displacement amount of the most advanced intake valve 118 and the waveform IN (broken line) of the valve displacement amount of the most retarded intake valve 118 are shown in FIG. Although illustrated, in particular, the change range of the valve opening timing of the electric VVT device 400 is not limited to between CA (0) and CA (1) shown in FIG.

  Next, problems during traveling (hereinafter referred to as “EV traveling”) using the power of motor generators MG1, MG2 with engine 100 stopped will be described.

FIG. 4 is a diagram for explaining the conventional EV performance.
The horizontal axis in FIG. 4 represents the rotational speed N, and the vertical axis represents the torque T. In FIG. 4, a line L1 representing torque that can be output with the maximum torque of motor generator MG2 and a line L2 representing torque that can be output when the power of power storage device 10 is used to the maximum are shown.

Conventionally, the E control device 200 outputs driving force only with MG2 during EV traveling.
However, as shown in FIG. 4, since the output possible line (maximum output power) of power storage device 10, that is, the torque generated by the maximum output of power storage device 10, is larger than the maximum torque of motor generator MG2, EV traveling In some cases, the power of the power storage device 10 could not be used to 100%. As a result, if the driver depresses the accelerator during EV travel, the required power cannot be output, and thus EV travel has been cancelled.

  In order to increase the power output from the power storage device 10, it is conceivable that the motor generator MG1 also outputs a driving force. However, this has problems as described below.

FIG. 5 is a collinear diagram for explaining conventional torque generation control during EV traveling.
By configuring the power split device 4 as described with reference to FIG. 1, the rotational speed of the sun gear S, the rotational speed of the carrier C, and the rotational speed of the ring gear R are connected in a straight line on the alignment chart. Have a relationship. The rotation speed of sun gear S is equal to the rotation speed Nm1 of motor generator MG1, the rotation speed of carrier C is equal to the rotation speed Ne of engine, and the rotation speed of ring gear R is equal to the rotation speed Nm2 of motor generator MG2. Therefore, the rotational speed Nm1 of motor generator MG1, the rotational speed Ne of engine, and the rotational speed Nm2 of motor generator MG2 are related 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. Hereinafter, the torque of engine 100 is represented as “torque Te”, the torque of motor generator MG1 is represented as “torque Tm1”, and the torque of motor generator MG2 is represented as “torque Tm2”.

  Since vehicle 1 is traveling, rotation speed Nm2 of motor generator MG2 is positive. Torque Tm2 of motor generator MG2 is controlled so as to satisfy the drive torque required by the user (requested drive torque). On the other hand, since engine 100 is stopped, rotation speed Ne and torque Te are zero.

  If the motor generator MG1 produces driving force during EV traveling, the torque 100 is applied to the side where the engine 100 rotates in reverse, and therefore the engine 100 is broken. That is, since the motor generator MG1, the motor generator MG2, and the engine 100 are connected on the battle map, the torque Tm1 of the motor generator MG1 exceeding the engine friction (friction loss of the engine 100) cannot be output.

  FIG. 6 is an alignment chart for explaining torque generation control during EV traveling in the present embodiment.

  In the present embodiment, the engine friction is increased by advancing the valve opening timing of electric VVT device 400. Thus, torque Tm1 of motor generator MG1 can be output. As a result, the power output from the power storage device 10 increases and the driving force increases. The valve closing timing is also advanced by advancing the valve opening timing.

  FIG. 7 is a diagram for explaining the relationship between the advance angle of the valve opening timing of the electric VVT device 400 and the increase in engine friction.

  The amount of air entering the cylinder 106 is increased by advancing the valve opening timing of the electric VVT device 400 (ST1). As a result, the compression ratio in the cylinder 106 increases (ST2). As a result, the internal pressure of the cylinder 106 increases (ST3). Therefore, a force for pushing the piston 114 is required (ST4). As a result, engine friction increases (ST4).

  FIG. 8 is a flowchart showing a procedure of EV travel control by control device 200 in the first embodiment. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  Referring to FIG. 8, when the processing of this flowchart is started, in step S101, it is determined whether or not EV traveling is being performed only with torque Tm2 by motor generator MG2. During EV travel, the motor generator MG2 drives the vehicle while the operation of the engine 100 is stopped.

  Here, the EV traveling includes retreat traveling (MD traveling) that travels without driving the engine 100 when the engine 100 fails.

  Control device 200 determines at any time whether to perform EV traveling or HV traveling with reference to the SOC, vehicle speed, and user operation mode changeover switch (eco mode / power mode, etc.) of power storage device 10.

  If it is determined in step S10 that the motor generator MG2 torque Tm2 alone is not being used for EV travel (NO in S101), the control is returned to the main routine. If it is determined in step S101 that the EV running is performed only with motor generator MG2 torque Tm2 (YES in S101), the process proceeds to step S102.

  In step S102, the control device 200 calculates the required drive torque Tr * based on the accelerator opening Acc and the vehicle speed V. If the requested driving torque Tr * exceeds the maximum torque of motor generator MG2 as a result of the user depressing the accelerator (YES in S102), control device 200 advances the process to step S103. If requested drive torque Tr * is equal to or less than the maximum torque of motor generator MG2 (NO in S102), control device 200 causes the process to proceed to step S104.

  In step S103, control device 200 increases engine friction by advancing the valve opening timing of electric VVT device 400, and at the same time or after that, permits output of negative torque Tm1 of motor generator MG1 to store power. The power output from the device 10 increases. As a result, it is permitted to increase the drive torque using motor generator MG1. The range to be increased has the upper limit of the output possible line (maximum output power) of the power storage device 10.

  In step S104, control device 200 performs control so as to continue traveling only with torque Tm2 of motor generator MG2.

[Second Embodiment]
The present embodiment relates to control in a case where it is necessary to start engine 100 as a result of a decrease in SOC during EV traveling while advancing the valve opening timing of electric VVT device 400.

  FIG. 9 is a flowchart showing a procedure of EV travel control by control device 200 in the second embodiment. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  In step S301, when EV traveling is being performed while the valve opening timing of the electric VVT device 400 is advanced, the process proceeds to step S302.

  In step S302, if the SOC is less than the threshold value TH, the process proceeds to step S303. If the SOC is greater than or equal to the threshold value TH, the process proceeds to step S304.

  In step S303, control device 200 sets the valve opening timing of electric VVT device 400 to the most retarded angle in advance in preparation for engine 100 being turned on. As a result, the engine friction is reduced and the engine 100 is likely to start. Note that the valve closing timing is also set to the re-retarding angle by setting the valve opening timing to the re-retarding angle.

  In step S304, control device 200 performs control so that the vehicle continues to run only with torque Tm2 of motor generator MG2.

  As described above, according to the present embodiment, there is a high possibility that the engine is started when the SOC decreases during EV traveling while the valve opening timing of electric VVT device 400 is advanced. By setting the valve opening timing of 400 to the most retarded angle, the engine can be started smoothly.

[Third Embodiment]
The present embodiment relates to a technique for protecting engine 100 when torque Tm1 of motor generator MG1 becomes too large during EV traveling.

  FIG. 10 is a flowchart showing a procedure of EV travel control by control device 200 in the third embodiment. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  In step S401, when EV traveling is being performed while the valve opening timing of the electric VVT device 400 is advanced, the process proceeds to step S402.

  In step S402, when engine 100 rotates in the negative direction (reverse rotation) as a result of torque Tm1 of motor generator MG1 being greater than engine friction, the process proceeds to step S403, and engine 100 is in the negative direction. If it is not rotated (reversely rotated), the process proceeds to step S404.

  In step S403, control device 200 decreases the torque of motor generator MG1. Thereby, reverse rotation of engine 100 can be continued and engine 100 can be prevented from being damaged.

  In step S404, control device 200 performs control so that the vehicle continues to run only with torque Tm2 of motor generator MG2.

  As described above, according to the present embodiment, when the engine rotates in reverse during EV traveling while the valve opening timing of electric VVT device 400 is advanced, the torque of MG1 is reduced. It can be prevented from being damaged.

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

  DESCRIPTION OF SYMBOLS 1 Hybrid vehicle, 4 Power split device, 5 Reducer, 6 Drive wheel, 10 Power storage device, 100 Engine, 104 Throttle valve, 106 Cylinder, 108 injector, 110 Spark plug, 112S, 112U Catalyst, 114 Piston, 116 Crankshaft, 118 intake valve, 120 exhaust valve, 122,124 cam, 200 control device, 300 cam angle sensor, 302 crank angle sensor, 306 throttle opening sensor, 312 throttle motor, 400 electric VVT device.

Claims (1)

An engine whose opening and closing timing can be changed by a variable valve mechanism while maintaining the opening period of the intake valve;
A first motor generator;
A second motor generator;
A power split device having three rotating elements respectively connected to the rotating shaft of the engine, the rotating shaft of the first motor generator, and the rotating shaft of the second motor generator;
A drive wheel coupled to the rotating shaft of the second motor generator;
A control device for controlling the engine, the first motor generator, and the second motor generator;
The controller is configured to advance the opening / closing timing of the intake valve when the required drive torque exceeds the maximum torque of the second motor generator during EV travel using only the torque of the second motor generator. A hybrid vehicle that allows the variable valve mechanism to operate and increases the drive torque using the first motor generator.

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