JP2008024287A - Control device of hybrid electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately suppress torque variation of a driving shaft of a wheel when an engine is started by a first MG (motor generator), in a hybrid electric vehicle which mounts an engine and first and second MGs. <P>SOLUTION: When starting the engine by cranking the engine with torque of the first MG, variation of inertia torque is reduced by correcting the torque (cranking torque) of the first MG according to an engine crank angle so as not to change the increase of engine rotation speed. After reducing the variation of cranking reaction force torque which reduces variation of the inertia torque by torque control of this first MG and acts on driving shaft, the torque of the second MG is controlled to cancel the cranking reaction force torque (that is, torque of small variation). Thereby, torque variation of the driving shaft is suppressed with high accuracy by canceling the cranking reaction force torque which acts on the driving shaft by torque control of the second MG with high accuracy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control apparatus for a hybrid electric vehicle in which an internal combustion engine, a first motor generator, and a wheel drive shaft are connected via a power split mechanism and a second motor generator is connected to the drive shaft. .

  In recent years, the demand for hybrid electric vehicles is rapidly expanding due to the social demand for low fuel consumption and low exhaust emissions. As described in Patent Document 1 (Japanese Patent Laid-Open No. 2005-90307), a hybrid electric vehicle currently on the market is an internal combustion engine and a first MG (motor generator mainly used as a generator). ) And a second MG that mainly drives the wheels, the crankshaft of the internal combustion engine is connected to the planetary gear carrier of the planetary gear mechanism that is a power split mechanism, and the first MG is connected to the sun gear of the planetary gear mechanism. In many cases, the second MG and the wheel drive shaft are connected to the ring gear.

  In the hybrid electric vehicle of this system, as shown in FIGS. 2 and 3, when the engine (internal combustion engine) is cranked with the first MG and the engine is started, the torque Tmg1 (that is, the first MG) A portion of the cranking torque) is transmitted to the drive shaft by the planetary gear mechanism, and the inertia torque due to the first MG and the inertia of the engine (inertia) is generated by the change in rotational speed due to cranking. The cranking reaction force torque Tep, which is the sum of the torque transmitted from the first MG and the inertia torque, acts.

  However, as shown in FIGS. 3 and 4, if the engine speed change amount Dne (rotation speed increase amount) fluctuates due to engine in-cylinder pressure fluctuation at the time of cranking, the inertia torque fluctuates and the drive shaft changes. Since the acting cranking reaction force torque Tep fluctuates, if nothing is done, the drive shaft torque Td may fluctuate and uncomfortable vehicle vibration may occur.

As a countermeasure against this, in Patent Document 1, when the engine is cranked with the first MG and the engine is started, the torque transmitted from the first MG to the drive shaft and the inertia torque ( The torque fluctuation of the drive shaft is suppressed by controlling the torque of the second MG so that the pulsation torque) is canceled out by the torque of the second MG.
JP-A-2005-90307

  However, in Patent Document 1, since it is necessary to cancel the inertia torque (pulsation torque) that greatly varies due to cranking with the torque of the second MG, the inertia torque that varies greatly is accurately controlled by the torque control of the second MG. In order to cancel the torque fluctuation of the drive shaft with high accuracy, it is necessary to increase the calculation cycle of the torque control of the second MG, and there is a disadvantage that the calculation load of the control device increases.

  The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to accurately suppress torque fluctuations of the drive shaft and to reduce the calculation load of the control device. An object of the present invention is to provide a control device for a hybrid electric vehicle.

  In order to achieve the above object, an invention according to claim 1 connects an internal combustion engine, a first motor generator (hereinafter referred to as “first MG”), and a wheel drive shaft via a power split mechanism. In addition, in a control apparatus for a hybrid electric vehicle in which a second motor generator (hereinafter referred to as “second MG”) is connected to the drive shaft, the internal combustion engine is started when the internal combustion engine is started with the torque of the first MG. The first MG torque control means controls the torque of the first MG so that the amount of change in the rotational speed of the engine does not fluctuate, and the torque that acts on the drive shaft when starting the internal combustion engine with the first MG torque The torque of the second MG is controlled by the second MG torque control means so as to cancel out.

  In this configuration, when the internal combustion engine is started with the torque of the first MG, the amount of change in the rotational speed of the internal combustion engine is controlled by controlling the torque of the first MG so that the amount of change in the rotational speed of the internal combustion engine does not vary. Can be made substantially constant, and fluctuations in inertia torque can be reduced. Consequently, fluctuations in torque acting on the drive shaft (= torque transmitted from the first MG + inertia torque) can be reduced. In this way, with the first MG torque control, the fluctuation of the inertia torque is reduced, the fluctuation of the torque acting on the drive shaft is reduced, and the torque acting on the drive shaft (that is, the torque with a small fluctuation) is reduced. By controlling the torque of the second MG so as to cancel, the torque acting on the drive shaft can be accurately canceled by the torque control of the second MG even if the torque control of the second MG is not so accelerated. It becomes possible. Thereby, when starting the internal combustion engine with the torque of the first MG, the torque fluctuation of the drive shaft can be suppressed with high accuracy and the calculation load of the control device can be reduced.

  Furthermore, as in claims 2 and 3, when the internal combustion engine is stopped with the first MG torque, the first MG torque is controlled so that the amount of change in the rotational speed of the internal combustion engine does not fluctuate. The torque of the second MG may be controlled so as to cancel the torque acting on the drive shaft when the internal combustion engine is stopped with the torque of MG.

  In this way, when the internal combustion engine is stopped with the first MG torque, the torque control of the first MG reduces the fluctuation of the inertia torque and the fluctuation of the torque acting on the drive shaft. By controlling the torque of the second MG so as to cancel the torque acting on the drive shaft, the torque acting on the drive shaft can be accurately canceled by the torque control of the second MG. When the internal combustion engine is stopped with the torque of 1 MG, the torque fluctuation of the drive shaft can be suppressed with high accuracy and the calculation load of the control device can be reduced.

  Further, as a specific method for controlling the torque of the first MG so that the amount of change in the rotational speed of the internal combustion engine does not fluctuate, as in claim 4, the first MG is controlled according to the crank angle of the internal combustion engine. Control may be performed so that the amount of change in the rotational speed of the internal combustion engine does not fluctuate by correcting the torque. When starting (or stopping) the internal combustion engine with the torque of the first MG, if the torque of the first MG is made substantially constant, the amount of change in rotational speed decreases in the latter half of the compression stroke of each cylinder of the internal combustion engine, Since the phenomenon that the amount of change in rotational speed increases in the first half of the expansion stroke of each cylinder occurs, the rotational speed change of the internal combustion engine is corrected by increasing the torque of the first MG at the crank angle corresponding to the second half of the compression stroke of each cylinder. If the increase in the amount of change in the rotation speed of the internal combustion engine is prevented by preventing the decrease in the amount and correcting the decrease in the torque of the first MG at the crank angle corresponding to the first half of the expansion stroke of each cylinder, The amount of inertia torque can be reduced by making the amount substantially constant.

  Alternatively, as described in claim 5, the amount of change in the rotational speed of the internal combustion engine fluctuates by feedback controlling the torque of the first MG so that the amount of change in the rotational speed of the internal combustion engine matches the target amount of change in the rotational speed. You may make it control so that it may not. In this way, the amount of change in the rotational speed of the internal combustion engine can be made to coincide with the amount of change in the target rotational speed, and fluctuations in the amount of change in rotational speed of the internal combustion engine are reliably suppressed, and fluctuations in inertia torque are reliably reduced. can do.

  Further, as in claim 6, when the rotational speed of the internal combustion engine is in the resonance frequency band, the torque of the first MG may be controlled so that the amount of change in the rotational speed of the internal combustion engine does not fluctuate. In this way, it is possible to reduce the resonance shock when the rotation speed of the internal combustion engine passes through the resonance frequency band when the internal combustion engine is started (or stopped).

  In this case, as in claim 7, it is preferable to determine whether or not the resonance frequency band is based on the rotational speed of the internal combustion engine. In this way, it can be accurately determined whether or not the rotational speed of the internal combustion engine is in the resonance frequency band.

  Hereinafter, the best mode for carrying out the present invention will be described using two Examples 1 and 2.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of a drive system for a hybrid electric vehicle will be described with reference to FIG. The hybrid electric vehicle includes an engine 11 which is an internal combustion engine, a first motor generator (hereinafter referred to as “first MG”) 12 and a second motor generator (hereinafter referred to as “second MG”) 13. And the engine 11 and the second MG 13 serve as a power source for driving the wheels 14. The power of the crankshaft 15 of the engine 11 is divided into two systems by a planetary gear mechanism 16 that is a power split mechanism. The planetary gear mechanism 16 includes a sun gear 17 that rotates at the center, a planetary gear 18 that revolves while rotating on the outer periphery of the sun gear 17, and a ring gear 19 that rotates on the outer periphery of the planetary gear 18. The crankshaft 15 of the engine 11 is connected through a non-carrier, the rotating shaft of the second MG 13 and the drive shaft 20 of the wheel 14 are connected to the ring gear 19, and the sun gear 17 is used mainly as a generator. The rotating shaft of 1 MG12 is connected.

  The first MG 12 and the second MG 13 exchange power with the battery 29 via inverters 27 and 28, respectively. A crank angle sensor 31 that outputs a pulse signal every time the crankshaft 15 rotates a predetermined crank angle is attached to the engine 11, and the crank angle and the engine rotation speed are detected based on the output signal of the crank angle sensor 31. Is done. Furthermore, the first MG 12 and the second MG 13 are provided with rotational position sensors 32 and 33 for detecting the rotational position of the rotor, respectively, and the first MG 12 is based on the output signals of these rotational position sensors 32 and 33. And the rotation speed of the second MG 13 are detected.

  The hybrid ECU 30 is a computer that comprehensively controls the entire hybrid electric vehicle, and includes an accelerator sensor 21 that detects an accelerator opening, a shift switch 22 that detects a shift range of an automatic transmission, a brake switch 23 that detects a brake operation, and the like. The output signals of the various sensors and switches are read, the driving state of the vehicle is detected, and the required travel mode is determined. The hybrid ECU 30 includes an engine ECU 24 that controls the operation of the engine 11, a first MG-ECU 25 that controls the operation of the first MG 12, and a second MG-ECU 26 that controls the operation of the second MG 13. Control signals are transmitted and received between the ECUs 24 to 26, and the operations of the engine 11, the first MG 12, and the second MG 13 are controlled according to the required travel mode.

  For example, at the time of starting or low / medium speed travel (region where the fuel efficiency of the engine 11 is poor), the motor travel mode is selected in which the engine 11 is kept stopped and travel is performed only with the power of the second MG 13. In this motor travel mode, the drive shaft 20 is driven only by the power of the second MG 13 to drive the wheels 14. At this time, a part of the rotational force of the second MG 13 is transmitted to the ring gear 19 of the planetary gear mechanism 16, whereby the ring gear 19 rotates, the planetary gear 18 rotates, and the sun gear 17 rotates. The MG 12 is driven to rotate.

  Further, when the engine 11 is started during the motor travel mode, torque is generated in the first MG 12 to act on the sun gear 17 of the planetary gear mechanism 16, thereby causing the planetary gear along the outer periphery of the sun gear 17. By changing the revolution speed of 18, the crankshaft 15 of the engine 11 is rotationally driven to start the engine 11.

  During normal driving, the power of the crankshaft 15 of the engine 11 is driven by the planetary gear mechanism 16 so that the fuel efficiency of the engine 11 is maximized and the drive shaft 20 side (rotation shaft side of the second MG13). ), The drive shaft 20 is driven by the output of one of the systems to drive the wheels 14, the first MG 12 is driven by the output of the other system, and the power generated thereby is supplied to the second system. The wheel 14 is also driven by the power of the second MG 13 supplied to the MG 13.

At the time of sudden acceleration, the most torque is required. Therefore, in addition to the generated power during normal driving, the direct current power of the battery 29 is added and converted into alternating current power by the inverter 28 and supplied to the second MG 13. The MG 13 is operated. Thus, the acceleration performance is improved by driving the drive shaft 20 with the power of both the engine 11 and the second MG 13 to drive the wheels 14.
At the time of deceleration or braking, the wheel 14 drives the second MG 13 to act as a generator, converts the deceleration energy and braking energy of the vehicle into electric power, and charges the battery 29.

As shown in FIGS. 2 and 3, when cranking the engine 11 with the first MG 12 and starting the engine 11, a part of the torque Tmg1 (that is, cranking torque) of the first MG 12 is obtained. In addition to being transmitted to the drive shaft 20 by the planetary gear mechanism 16, inertia torque due to the inertia of the first MG 12 and the engine 11 is generated by the change in rotational speed due to cranking. A cranking reaction force torque Tep obtained by summing the torque transmitted from the MG 12 (−Kgear × Tmg1) and the inertia torque (Kinr × Dne) acts.
Tep = (− Kgear × Tmg1) + (Kinr × Dne)

  Here, Kgear is a gear ratio between the sun gear 17 and the ring gear 19 (however, when the ring gear 19 and the drive shaft 20 are connected via a reduction mechanism, the reduction ratio of the reduction mechanism is also taken into consideration) Kinr is a coefficient based on the inertia of the first MG 12 and the engine 11, and Dne is a change amount (amount of increase) of the engine speed Ne.

  However, as shown in FIGS. 3 and 4, when the increase amount Dne of the engine speed Ne changes due to the in-cylinder pressure fluctuation of the engine 11 during cranking, the inertia torque (Kinr × Dne) fluctuates and the drive Since the cranking reaction force torque Tep acting on the shaft 20 fluctuates, if nothing is done, the torque Td of the drive shaft 20 may fluctuate and uncomfortable vehicle vibration may occur.

  Therefore, the hybrid ECU 30 executes a cranking torque calculation program shown in FIG. 6 to be described later, so that when the engine 11 is cranked with the torque of the first MG 12 and the engine 11 is started, the crank angle of the engine 11 is set. Accordingly, the basic cranking torque Tcrkbs is corrected to obtain a cranking torque Tcrk that does not fluctuate the engine speed increase. By controlling the torque of the first MG 12 so as to generate the cranking torque Tcrk, the fluctuation of the engine rotational speed increase is made substantially constant, and the fluctuation of the inertia torque is reduced. These functions serve as the first MG torque control means in the claims.

  When starting the engine 11 with the torque of the first MG 12, as shown in FIG. 4, when the torque (cranking torque) of the first MG 12 is made substantially constant, the compression stroke of each cylinder of the engine 11 is in the latter half of the compression stroke. Since the engine speed increase amount decreases and the engine speed increase amount increases in the first half of the expansion stroke of each cylinder, in the first embodiment, as shown in FIG. 5, in the second half of the compression stroke of each cylinder. The torque (cranking torque) of the first MG 12 is increased and corrected at a crank angle corresponding to the above to prevent a decrease in the engine speed increase, and at the crank angle corresponding to the first half of the expansion stroke of each cylinder, the first MG 12 By reducing the torque (cranking torque) to prevent an increase in the engine speed increase, the engine speed increase is made almost constant and fluctuations in inertia torque are reduced. .

  In this way, when starting the engine 11 with the torque of the first MG 12, the torque of the first MG 12 is corrected so that the amount of increase in the engine speed does not fluctuate so that the amount of increase in the engine speed is substantially constant. Thus, the fluctuation of the inertia torque can be reduced, and consequently the fluctuation of the cranking reaction force torque Tep (= the torque transmitted from the first MG 12 + the inertia torque) acting on the drive shaft 20 can be reduced. .

  Further, the hybrid ECU 30 executes a reaction force cancellation torque calculation program shown in FIG. 7 described later, so that when the engine 11 is started with the torque of the first MG 12, the same magnitude as the torque transmitted from the first MG 12 is obtained. The basic reaction force canceling torque Tcsbs is calculated, the inertia torque Tinr due to the inertia of the first MG 12 and the engine 11 is calculated, and the inertial torque Tinr is subtracted from the basic reaction force canceling torque Tcsbs. That is, the torque having the same magnitude as that of the cranking reaction force torque Tep acting on the drive shaft 20 is obtained. By controlling the torque of the second MG 13 so as to generate a torque obtained by adding the reaction force canceling torque Tcs to the required torque of the second MG 13, the cranking reaction force torque Tep acting on the drive shaft 20 is changed to the second. It cancels with the torque of MG13. These functions serve as second MG torque control means in the claims.

  In the torque control of the first MG 12 described above, the fluctuation of the inertia torque is reduced, the fluctuation of the cranking reaction force torque Tep acting on the drive shaft 20 is reduced, and the cranking reaction force torque Tep (that is, the fluctuation) By controlling the torque of the second MG 13 so as to cancel the torque of the second MG 13, the cranking reaction force torque Tep acting on the drive shaft 20 can be canceled with high accuracy by the torque control of the second MG 13.

  The processing contents of the cranking torque calculation program of FIG. 6 and the reaction force cancellation torque calculation program of FIG. 7 executed by the hybrid ECU 30 will be described below.

[Cranking torque calculation]
The cranking torque calculation program shown in FIG. 6 is executed at a predetermined cycle (for example, every 5 msec) when starting the engine 11 with the torque of the first MG 12. When this program is started, first, in step 101, parameters necessary for the current control, such as the engine speed Ne and the crank angle, are read.

  Thereafter, the routine proceeds to step 102, where the basic cranking torque Tcrkbs is calculated based on the engine rotational speed Ne and the like. As shown in the time chart of FIG. 8, the basic cranking torque Tcrkbs increases rapidly to the vicinity of the maximum value immediately after the cranking of the engine 11 starts, and then the engine rotational speed Ne reaches the resonance frequency band. The basic cranking torque Tcrkbs is set so as to be maintained near the maximum value until it passes. As a result, the engine rotational speed Ne is quickly raised so as to pass through the resonance frequency band quickly. After the engine rotational speed Ne passes through the resonance frequency band, the basic cranking torque Tcrkbs is set to gradually decrease.

Thereafter, the process proceeds to step 103, where it is determined whether or not the current engine speed Ne is in a resonance frequency band (for example, a band near 300 rpm).
If it is determined in step 103 that the engine speed Ne is in the resonance frequency band, the routine proceeds to step 104, where the current crank angle of the engine 11 is referred to with reference to the map of the torque correction amount V1 shown in FIG. A torque correction amount V1 corresponding to the above is calculated. The map of the torque correction amount V1 shown in FIG. 9 shows that the torque correction amount V1 becomes a positive value when the crank angle corresponding to the second half of the compression stroke of each cylinder of the engine 11 is obtained, and the crank angle corresponding to the first half of the expansion stroke of each cylinder is shown. The torque correction amount V1 is sometimes set to a negative value.

  By setting the torque correction amount V1 based on the engine stop position (crank angle) immediately before the cranking start and the elapsed time since the cranking start, the torque correction amount according to the crank angle is set as in FIG. V1 may be changed.

On the other hand, if it is determined in step 103 that the engine speed Ne is not in the resonance frequency band, the routine proceeds to step 105, where the torque correction amount V1 is set to zero.
Thereafter, the routine proceeds to step 106, where the final cranking torque Tcrk is obtained by adding the torque correction amount V1 to the basic cranking torque Tcrkbs.
Tcrk = Tcrkbs + V1

  The torque of the first MG 12 is controlled so as to generate the cranking torque Tcrk. Accordingly, when the engine 11 is cranked with the torque of the first MG 12 and the engine 11 is started, when the engine speed Ne is in the resonance frequency band, the crank angle corresponding to the latter half of the compression stroke of each cylinder of the engine 11 To increase the cranking torque Tcrk to prevent a decrease in the engine speed increase, and to reduce the cranking torque Tcrk at the crank angle corresponding to the first half of the expansion stroke of each cylinder to increase the engine speed increase. By preventing this, the amount of increase in the engine rotation speed is made substantially constant, and fluctuations in inertia torque are reduced.

[Reaction force cancellation torque calculation]
The reaction force cancellation torque calculation program shown in FIG. 7 is executed at a predetermined cycle (for example, every 5 msec) when the engine 11 is started with the torque of the first MG 12. When this program is started, first, in step 201, the cranking torque Tcrk (the torque of the first MG 12) is multiplied by the gear ratio Kgear to obtain a basic signal having the same magnitude as the torque transmitted from the first MG 12. The reaction force cancellation torque Tcsbs is obtained.
Tcsbs = Tcrk x Kgear

Thereafter, the routine proceeds to step 202, where the difference between the current engine speed Ne and the previous engine speed Ne (i-1) is obtained, and this is set as the increase amount Dne of the engine speed Ne.
Dne = Ne-Ne (i-1)

After this, the routine proceeds to step 203, where the coefficient Kinr based on the inertia of the first MG 12 and the engine 11 is multiplied by the increase amount Dne of the engine speed Ne, and the inertia torque Tinr due to the inertia of the first MG 12 and the engine 11 is obtained. Ask.
Tinr = Kinr x Dne
The coefficient Kinr is stored in a ROM such as the hybrid ECU 30 in advance as a value calculated based on design data, experimental data, and the like.

Thereafter, in step 204, the inertial torque Tinr is subtracted from the basic reaction force cancellation torque Tcsbs to reduce the reaction force cancellation torque Tcs (that is, the reverse torque having the same magnitude as the cranking reaction force torque Tep acting on the drive shaft 20). Ask for.
Tcs = Tcsbs-Tinr

  By controlling the torque of the second MG 13 so as to generate a torque obtained by adding the reaction force canceling torque Tcs to the required torque of the second MG 13, the cranking reaction force torque Tep acting on the drive shaft 20 is changed to the second. It cancels with the torque of MG13.

  In the first embodiment described above, when the engine 11 is cranked with the torque of the first MG 12 and the engine 11 is started as shown in the time chart of FIG. By correcting the torque (cranking torque) of 1 MG12, the engine rotation speed increase amount is prevented from fluctuating, so that the engine rotation speed increase amount can be made substantially constant and the fluctuation of the inertia torque can be reduced. As a result, fluctuations in the cranking reaction force torque Tep (= torque transmitted from the first MG 12 + inertia torque) acting on the drive shaft 20 can be reduced.

  As described above, the torque control of the first MG 12 reduces the variation of the inertia torque, reduces the variation of the cranking reaction force torque Tep acting on the drive shaft 20, and then the cranking reaction force torque Tep ( In other words, the torque of the second MG 13 is controlled so as to cancel out the torque having a small fluctuation), so that the cranking reaction force torque acting on the drive shaft 20 can be achieved even if the torque control of the second MG 13 is not made much faster. It becomes possible to cancel Tep with high accuracy by the torque control of the second MG 13. As a result, when the engine 11 is started with the torque of the first MG 12, the torque fluctuation of the drive shaft 20 can be accurately suppressed to reduce vehicle vibration, and the calculation load of the hybrid ECU 30 and the MG-ECU 26 can be reduced. Can be reduced. Even if the calculated value of the inertia torque is slightly deviated from the actual inertia torque, the fluctuation of the inertia torque can be reduced, so that the vehicle vibration can be reduced.

  In the first embodiment, when the engine 11 of the first MG 12 is started, the torque of the first MG 12 is controlled so that the engine rotation speed increase does not fluctuate when the engine rotation speed Ne is in the resonance frequency band. Thus, the resonance shock when the engine speed Ne passes through the resonance frequency band when the engine is started can be reduced.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
In the first embodiment, when the engine 11 is started with the first MG 12, the torque of the first MG 12 is corrected according to the crank angle of the engine 11 so that the engine rotation speed increase amount does not fluctuate. In the second embodiment, the cranking torque calculation program of FIG. 10 is executed, so that when the engine 11 is started by the first MG 12, the increase amount of the engine rotation speed is made to coincide with the target increase amount. The amount of increase in engine speed is prevented from fluctuating by F / B (feedback) control of the torque of one MG12.

  The cranking torque calculation program shown in FIG. 10 is executed at a predetermined cycle (for example, every 5 msec) when starting the engine 11 with the torque of the first MG 12. When this program is started, first, in step 301, parameters necessary for the current control, such as the engine speed Ne and the crank angle, are read.

Thereafter, the routine proceeds to step 302, where the basic cranking torque Tcrkbs is calculated based on the engine rotational speed Ne, etc., and then proceeds to step 303, where the current engine rotational speed Ne and the previous engine rotational speed Ne (i-1) are determined. Is obtained, and this is set as the increase amount Dne of the engine speed Ne.
Dne = Ne-Ne (i-1)

Thereafter, the routine proceeds to step 304, where it is determined whether or not the current engine speed Ne is in a resonance frequency band (for example, a band near 300 rpm).
If it is determined in step 304 that the engine rotational speed Ne is in the resonance frequency band, the process proceeds to step 305, in which it is determined whether or not it is the first calculation cycle immediately after it is determined to be in the resonance frequency band. If it is the first calculation cycle, the routine proceeds to step 306, where the increase amount Dne of the engine rotation speed Ne is multiplied by the coefficient K to obtain the target increase amount Dnet of the engine rotation speed Ne.
Dnet = K × Dne

  In the case of the engine 11 having a small in-cylinder pressure fluctuation at the time of cranking, the coefficient K may be a fixed value. However, in the case of the engine 11 having a large in-cylinder pressure fluctuation at the time of cranking, It is preferable to increase the coefficient K at the crank angle corresponding to the second half of the compression stroke and decrease the coefficient K at the crank angle corresponding to the first half of the expansion stroke of each cylinder. Since the engine speed increase amount decreases in the second half of the compression stroke of each cylinder and the engine speed increase amount increases in the first half of the expansion stroke of each cylinder, the coefficient K is increased in the second half of the compression stroke of each cylinder. By reducing the coefficient K in the first half of the expansion stroke of each cylinder, the target increase amount Dnet can be made substantially constant.

  Note that by setting the coefficient K based on the engine stop position (crank angle) immediately before the start of cranking and the elapsed time from the start of cranking, the coefficient K is increased in the second half of the compression stroke of each cylinder, and the expansion of each cylinder is increased. The coefficient K may be reduced in the first half of the stroke.

  Thereafter, the process proceeds to step 307, where the target increase amount Dnet of the engine rotational speed Ne is guarded with the upper limit guard value GDH and the lower limit guard value GDL, thereby preventing the target increase amount Dnet from being excessively large or small. This prevents the F / B correction amount from becoming excessively large and the engine rotational speed increase from fluctuating.

Thereafter, the process proceeds to step 308, and the current engine speed Ne is substituted as the initial value of the target engine speed Net.
Net = Ne

On the other hand, in step 305, it is determined that it is not the first calculation cycle immediately after it is determined to be the resonance frequency band (that is, the calculation cycle after the second time after the determination is made to be the resonance frequency band). In this case, the process proceeds to step 309, and the current target engine speed Net is obtained by adding the target increase amount Dnet to the previous target engine speed Net (i-1).
Net = Net (i-1) + Dnet

  Thereafter, the routine proceeds to step 310, where the torque correction amount V1 corresponding to the current crank angle of the engine 11 is calculated with reference to the map of the torque correction amount V1 of FIG. Then, based on the target engine speed Net and the actual engine speed Ne, the F / B correction amount V2 is calculated so that the deviation between the target engine speed Net and the actual engine speed Ne is small. The F / B correction amount V2 is set so that the increase amount Dne of the engine rotation speed Ne matches the target increase amount Dnet.

  On the other hand, if it is determined in step 304 that the engine speed Ne is not in the resonance frequency band, the process proceeds to step 312 and the torque correction amount V1 is set to 0, and then the process proceeds to step 313 to perform F / B correction. The quantity V2 is set to zero.

Thereafter, the process proceeds to step 314, where the final cranking torque Tcrk is obtained by adding the torque correction amount V1 and the F / B correction amount V2 to the basic cranking torque Tcrkbs.
Tcrk = Tcrkbs + V1 + V2

  By controlling the torque of the first MG 12 so as to generate the cranking torque Tcrk, the torque of the first MG 12 is changed to F / B so that the increase amount Dne of the engine rotation speed Ne matches the target increase amount Dnet. Control to prevent the engine speed increase from fluctuating.

  In the second embodiment described above, when the engine 11 is cranked with the torque of the first MG 12 and the engine 11 is started, the increase amount Dne of the engine rotational speed Ne is matched with the target increase amount Dnet. The torque of the MG 12 of 1 is F / B controlled so that the engine speed increase amount does not fluctuate. Therefore, the fluctuation of the engine speed increase amount can be surely suppressed and the fluctuation of the inertia torque can be surely reduced. it can.

  In each of the first and second embodiments, when the engine 11 is started with the torque of the first MG 12, the first engine rotational speed increase amount is not changed when the engine rotational speed Ne is in the resonance frequency band. Although the torque of the MG 12 is controlled, when starting the engine 11 with the torque of the first MG 12, the engine speed increase amount is not changed in the entire region or a part of the cranking region. The torque of one MG 12 may be controlled.

  Further, in each of the first and second embodiments, it is determined whether or not the resonance frequency band is based on the engine rotational speed. However, information correlated with the engine rotational speed (for example, the first MG 12 It may be determined whether or not the resonance frequency band is based on the rotation speed, the elapsed time from the start of cranking, and the like.

  In the first and second embodiments, the present invention is applied to the control when starting the engine 11 with the torque of the first MG 12. However, the control for stopping the engine 11 with the torque of the first MG 12 is used. The present invention may be applied. That is, when the engine 11 is stopped with the torque of the first MG 12, the torque of the first MG 12 is controlled so that the engine rotational speed decrease does not fluctuate, so that the engine rotational speed decrease is substantially constant, The torque acting on the drive shaft 20 is reduced after the variation in the inertia torque is reduced and the torque control of the first MG 12 is performed to reduce the variation in the inertia torque and the torque acting on the drive shaft 20 is reduced. The torque of the second MG 13 may be controlled so as to cancel out (that is, torque with small fluctuation).

It is a figure which shows schematic structure of the drive system of the hybrid electric vehicle in Example 1 of this invention. It is a collinear diagram which shows the relationship of the rotational speed of each part at the time of cranking. It is a figure for demonstrating the cranking reaction force torque Tep which acts on a drive shaft. It is a time chart which shows an example of the control at the time of engine starting in a comparative example. 3 is a time chart showing an example of control at the time of engine start in the first embodiment. It is a flowchart which shows the flow of a process of the cranking torque calculation program of Example 1. It is a flowchart which shows the flow of a process of the reaction force cancellation torque calculation program of Example 1. It is a time chart which shows an example of the behavior of basic cranking torque. It is a figure which shows notionally an example of the map of torque correction amount. It is a flowchart which shows the flow of a process of the cranking torque calculation program of Example 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... 1st MG, 13 ... 2nd MG, 16 ... Planetary gear mechanism (power split mechanism), 17 ... Sun gear, 18 ... Planetary gear, 19 ... Ring gear, 20 ... Drive shaft, 24 ... engine ECU, 25 ... first MG-ECU, 26 ... second MG-ECU, 27, 28 ... inverter, 29 ... battery, 30 ... hybrid ECU (first MG torque control means, second MG Torque control means), 31 ... crank angle sensor, 32, 33 ... rotational position sensor

Claims (7)

An internal combustion engine, a first motor generator (hereinafter referred to as “first MG”) and a drive shaft of a wheel are connected via a power split mechanism and a second motor generator (hereinafter referred to as “second” is connected to the drive shaft). In a control apparatus for a hybrid electric vehicle in which
First MG torque control means for controlling the torque of the first MG so that the amount of change in rotational speed of the internal combustion engine does not fluctuate when starting the internal combustion engine with the torque of the first MG;
Second MG torque control means for controlling the torque of the second MG so as to cancel the torque acting on the drive shaft when starting the internal combustion engine with the torque of the first MG. The control apparatus of the hybrid electric vehicle characterized by this. The first MG torque control means controls the torque of the first MG so that the amount of change in the rotational speed of the internal combustion engine does not fluctuate when the internal combustion engine is stopped with the torque of the first MG.
The second MG torque control means controls the torque of the second MG so as to cancel the torque acting on the drive shaft when the internal combustion engine is stopped with the torque of the first MG. The control apparatus for a hybrid electric vehicle according to claim 1. An internal combustion engine, a first motor generator (hereinafter referred to as “first MG”) and a drive shaft of a wheel are connected via a power split mechanism and a second motor generator (hereinafter referred to as “second” is connected to the drive shaft). In a control apparatus for a hybrid electric vehicle in which
First MG torque control means for controlling the torque of the first MG so that the amount of change in rotational speed of the internal combustion engine does not fluctuate when the internal combustion engine is stopped with the torque of the first MG;
Second MG torque control means for controlling the torque of the second MG so as to cancel the torque acting on the drive shaft when the internal combustion engine is stopped by the torque of the first MG. The control apparatus of the hybrid electric vehicle characterized by this.   The first MG torque control means controls the amount of change in the rotational speed of the internal combustion engine so as not to fluctuate by correcting the torque of the first MG according to the crank angle of the internal combustion engine. The control apparatus for a hybrid electric vehicle according to any one of claims 1 to 3.   The first MG torque control means feedback-controls the torque of the first MG so that the rotational speed change amount of the internal combustion engine coincides with the target rotational speed change amount, whereby the rotational speed change amount of the internal combustion engine is controlled. The control apparatus for a hybrid electric vehicle according to any one of claims 1 to 4, wherein the control is performed so as not to fluctuate.   The first MG torque control means controls the torque of the first MG so that the amount of change in the rotational speed of the internal combustion engine does not fluctuate when the rotational speed of the internal combustion engine is in a resonance frequency band. A control apparatus for a hybrid electric vehicle according to any one of claims 1 to 5.   The control apparatus for a hybrid electric vehicle according to claim 6, wherein the first MG torque control means determines whether or not the resonance frequency band is based on a rotation speed of the internal combustion engine.

Images