JP3797284B2 - Control device for hybrid powertrain for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a hybrid powertrain for a vehicle that includes an internal combustion engine and an electric / generator as drive sources and includes a stepped transmission.
[0002]
[Prior art]
In a hybrid powertrain for a vehicle having a stepped transmission having a plurality of speed stages between an internal combustion engine and drive wheels, the internal combustion engine is operated in a predetermined high-efficiency operation state, and the required driving force and engine output Has been disclosed (see Japanese Patent Application Laid-Open No. 2001-146121) for controlling the gear ratio and the engine operating state so that the difference between the two is filled by powering or regeneration of the electric motor / generator.
[0003]
[Problems to be solved by the invention]
However, in the above technique, depending on the state of charge (SOC) of the battery that charges and discharges with the electric motor / generator, the electric motor / generator may not be able to be powered or regenerated. Not.
The present invention has been made paying attention to such a conventional problem, and provides a control device for a hybrid powertrain for a vehicle that can control a driving force most efficiently in consideration of a state of charge of a battery. With the goal.
[0004]
[Means for Solving the Problems]
For this reason, the present invention
An internal combustion engine and an electric / generator as a traveling drive source, a battery that is charged / discharged between the electric / generator, and a stepped transmission that is disposed between the engine and drive wheels. In the hybrid powertrain for vehicles
Means for calculating the required drive output of the vehicle;
Corresponding to the gear ratio set by the stepped transmission, the best fuel efficiency driving when the required driving torque and the fuel efficiency when the internal combustion engine is operated to satisfy the required driving output is the best. Means for calculating a deviation from the torque;
Means for detecting the state of charge of the battery;
Means for calculating possible drive / regenerative torque of the electric / generator according to the state of charge of the battery;
When it is determined that the deviation between the required drive torque of the internal combustion engine and the best fuel efficiency drive torque cannot be covered by the drive / regenerative torque of the electric / generator according to the state of charge of the battery, the gear ratio of the stepped transmission Means for switching the gear ratio so that the torque deviation at the time of switching is covered by the drive / regenerative torque of the electric motor / generator according to the state of the battery ;
Constructed including.
[0005]
That is, according to the gear ratio set by the stepped transmission, torque when driving the internal combustion engine so as to satisfy the required drive output of the vehicle (required drive torque) and when operating the internal combustion engine with the best fuel consumption Since the deviation from the torque (the best fuel efficiency driving torque) is different, the gear ratio is set so that this deviation can be covered by the electric / generator based on the possible driving / regenerative torque of the electric / generator according to the state of charge of the battery. Therefore, the required drive output of the vehicle can be obtained while operating the internal combustion engine near the best fuel consumption characteristics.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows a drive control device for a hybrid vehicle according to an embodiment of the present invention. The traveling direction is leftward in the figure, with the front wheel on the left side and the rear wheel on the opposite right side.
[0007]
In this vehicle, a first electric motor / generator (hereinafter referred to as a first MG) 2 that functions as an electric motor or a generator is directly connected to the output side of the engine (internal combustion engine) 1, and is further connected to the engine 1 and the first MG 2. The torque converter 3 and the stepped transmission 4 are connected. Then, a wheel drive shaft 8 of the engine drive wheels (rear wheels 7 and 7 in this case) is connected via a rear wheel side differential 6 by a power transmission shaft (propeller shaft) 5 connected to the output side of the transmission 4. , 8 are driven.
[0008]
Here, the first MG 2 functions as an assist device for the engine 1 and performs cranking of the engine 1 when the engine 1 is started or when the vehicle starts. Further, during deceleration operation, the first MG 2 can function as a generator, regenerate braking energy to generate power, and can be used for charging the battery 14. Further, as will be described later, since the engine 1 is operated near the best fuel efficiency even when the vehicle is not decelerated as a configuration according to the present invention, it functions as a generator as required.
[0009]
On the other hand, a second motor / generator (hereinafter referred to as second MG) second MG 10 functioning as an electric motor or a generator is provided for the front wheels 9, 9 which are non-engine driving wheels, and is connected to the output side thereof. The drive torque generated by the second MG 10 via the power transmission shaft (relatively small propeller shaft) 11 and the front wheel side differential device 12 is the wheel drive shaft 13 of the front wheels (also referred to as “motor drive wheels”). , 13 so that a driving force can be obtained from the front wheel side.
[0010]
The second MG 10 is connected to the battery 14 constituting the power source via the inverter 15b. In a state where the driving torque is obtained from the second MG 10, the discharge power of the battery 14 is three-phase alternating current by the inverter 15. It is converted into electric power and supplied to the second MG 10.
The first MG2 is connected to the battery 14 via the inverter 15a. In a state where the driving torque is obtained from the first MG2, the discharge power of the battery 14 is converted into three-phase AC power by the inverter 15a, 1MG2 is supplied.
[0011]
Here, there is no physical connection between the rear wheel drive shafts 8 and 8 and the front wheel drive shafts 13 and 13, that is, it is possible to transmit drive torque independently to the front and rear drive shafts. The driving torque is transmitted to the rear wheel drive shafts 8 and 8 by the engine 1 and the first MG2, and to the front wheel drive shafts 13 and 13 by the second MG 10.
[0012]
In the normal driving mode, the vehicle driving force is generated by the FR method using only the rear wheels 7 and 7 as driving wheels. However, when the four-wheel driving driving mode is entered based on the driver's selection, the front wheels 9 and 9 On the other hand, when the driving torque of the second MG 10 is transmitted, both the front and rear wheels can be used as driving wheels, and the 4WD system can be established.
Next, the control system will be roughly described. A hybrid control module (hereinafter referred to as “HCM”) 21 as an integrated controller of the engine 1, the first MG 2 and the second MG 10 has an accelerator opening APO from an accelerator opening sensor 41. The vehicle speed V from the vehicle speed sensor 42 is changed from the wheel speed sensors 43 to 46 attached to the front and rear wheels 9, 9, 7, and 7, respectively, from the front right wheel rotational speed Nfr, the front left wheel rotational speed Nfl, and the rear right wheel. The rotation speed Nrr and the rear left wheel rotation speed Nrl are input from the rotation speed sensor 47 of the second MG 10. Further, a traveling mode switching signal is input from a 4WD selector switch 51 provided in the vehicle interior.
[0013]
The HCM 21 controls each control device (motor controller, hereinafter referred to as “M / C”) of the engine control module (hereinafter referred to as “ECM”) 31, the first MG 2 and the second MG 10 based on various operating conditions including such information. For 32 and 33, a control command is generated via the communication line 61.
In the present invention, the engine 1, the first MG 2 and the stepped transmission 4 are controlled to drive the engine 1 near the best fuel consumption characteristics while satisfying the required drive output of the vehicle.
[0014]
The control according to the present invention will be described below with reference to the flowcharts of FIGS.
In step 1, the vehicle speed and the accelerator opening are read, and the required drive output TW of the vehicle is calculated.
In step 2, as shown in FIG. 4, the required drive output TW is satisfied from the intersection of the best fuel efficiency characteristic α line set for the engine speed and engine torque and the equal TW line, and an arbitrary speed change is performed. The best fuel consumption rotational speed TNAL when the engine 1 is operated so as to obtain the best fuel consumption by the ratio is calculated.
[0015]
In step 3, an engine rotation speed TNGPi for each speed ratio i that satisfies the required drive output TW is calculated from the vehicle speed, the speed ratio, and the torque converter characteristics.
In step 4, a deviation | TNAL−TNGPi | between the best fuel efficiency rotation speed TNAL and the engine rotation speed TNGPi for each speed ratio i is calculated, and a speed ratio i that minimizes the deviation is selected.
[0016]
In step 5, the required drive torque TTNRAL when the engine 1 is operated to satisfy the required drive output TW at the selected gear ratio i, and the best fuel consumption drive torque TTAL when the engine 1 is operated to achieve the best fuel consumption. Is calculated.
In step 6, it is determined whether the required drive torque TTNRAL is equal to or greater than the best fuel consumption drive torque TTAL. If it is determined that TTNRAL ≧ TTAL, it is determined that an assist request is generated by the first MG 2, and the process proceeds to step 7.
[0017]
In step 7, a deviation torque (= TTNRAL-TTAL) between the required drive torque TTNRAL and the best fuel efficiency drive torque TTAL is calculated as the assist required torque ΔT.
In step 8, assistable torque (possible drive torque) Tmsoc is calculated based on the battery charge state SOC (state of charge) calculated in another routine. The battery state of charge SOC is calculated as follows. When the relay connecting the battery and the power supply circuit is OFF when the vehicle is stopped for a long time, the initial value of the state of charge SOC is obtained based on the initial value of the open circuit voltage of the battery, and then the charging / discharging current of the battery is charged The current state of charge SOC is calculated while integrating as + and-when discharging. As shown in FIG. 5B and FIG. 6B, the assistable torque Tmsoc is set to 0 when the battery state of charge SOC is less than a predetermined value, that is, the assist is impossible, and the assistable torque Tmsoc is rapidly increased beyond the predetermined value. And has a characteristic of being maintained at a substantially constant value.
[0018]
In step 9, it is determined whether the assist request torque ΔT (= TTNRAL−TTAL) calculated in step 7 is equal to or less than the assistable torque Tmsoc calculated in step 8.
When it is determined in step 9 that ΔT ≦ Tmsoca, it is determined that the first MG2 assist torque that covers the shortage of the drive torque of the engine 1 is obtained, and the routine proceeds to step 10 where the gear ratio i selected in step 5 is maintained. The engine 1 is controlled to operate at the best fuel efficiency drive torque TTAL, and the first MG 2 is controlled to be an electric motor so as to output an assist torque equal to the assist request torque ΔT (= TTNRAL−TTAL).
[0019]
If it is determined in step 9 that the requested assist torque ΔT exceeds the assistable torque Tmsoca, the requested drive output cannot be obtained even if the first MG2 is driven as an electric motor. The setting is such that the driving torque of the engine 1 is increased by shifting down by one stage. For example, as shown in FIG. 5, power is first supplied from the battery 14 to the first MG 2 in response to an assist request, and the first MG 2 is driven as an electric motor to assist, but as a result, the amount of charge of the battery 14 is insufficient. If the assist request torque ΔT cannot be obtained, the shift down is performed to increase the drive torque of the engine 1, and the first MG2 is switched to the power generation request.
[0020]
In step 12, when the engine 1 is driven to satisfy the required drive output TW at the gear ratio (i-1) shifted down by one step, and the engine is driven to achieve the best fuel consumption. The best fuel consumption driving torque TTAL is calculated.
This time, the best fuel consumption driving torque TTAL becomes larger than the required driving torque TTNAL due to the shift down, and switching is performed at the time of the regeneration request to operate the first MG2 as a generator. In step 13, power generation according to the battery charge state SOC is possible. Torque Tmsoc is calculated, and power generation required torque ΔT (= TTAL−TTNRAL) is calculated in step 14.
[0021]
In step 15, it is determined whether the power generation request torque ΔT is equal to or less than the power generation possible torque Tmsoc. If it is determined that ΔT ≦ Tmsoc, the first MG 2 that covers (can be canceled) the excess driving torque of the engine 1 The control proceeds to step 16 to set the gear ratio (i-1), and controls the engine 1 to operate at the best fuel efficiency driving torque TTAL calculated at step 12 to obtain the first MG2 As a generator, control is performed so as to output a power generation torque equal to the power generation required torque ΔT (= TTAL−TTNRAL) calculated in step 14.
[0022]
When it is determined in step 15 that the deviation torque ΔT exceeds the power generation possible torque Tmsoc, the engine 1 is operated at the best fuel consumption driving torque TTAL calculated in step 12 and the first MG2 is used as a generator. Even if the required drive output is not obtained, the gear ratio (i-1) is set at step 17, and the engine 1 is operated at the gear ratio (i-1) while operating the first MG2 as a generator. Is controlled to output. Alternatively, the engine 1 may be controlled to output the required drive torque TTNRAL at the gear ratio i while returning to the gear ratio i and operating the first MG 2 as an electric motor. In either case, the engine 1 cannot be operated with the best fuel efficiency, but can be operated with the best possible fuel efficiency while satisfying the required drive output of the vehicle.
[0023]
When it is determined in step 6 that the required drive torque TTNRAL is less than the best fuel consumption drive torque TTAL, it is first determined that a power generation request is generated by the first MG2, and thereafter the same control is performed.
That is, in step 18, the deviation (= TTAL-TTNRAL) between the best fuel efficiency driving torque TTAL and the required driving torque TTNRAL is calculated as the power generation required torque ΔT, and in step 19, the electric power generation possible torque Tmsoc corresponding to the battery charge state SOC is calculated. calculate. As shown in FIGS. 5 (C) and 6 (C), the power generation possible torque Tmsoc is maintained at a substantially constant value when the battery state of charge SOC is less than a predetermined value, but rapidly falls when the battery charge state SOC is less than the predetermined value. It has a characteristic that becomes 0 and power generation is impossible.
[0024]
In step 20, it is determined whether the power generation request torque ΔT is equal to or lower than the power generation possible torque Tmsoc. In the following case, it is determined that the power generation torque of the first MG 2 that covers the excess driving torque of the engine 1 can be obtained, and the process proceeds to step 21. The engine 1 is controlled to operate at the best fuel efficiency drive torque TTAL while maintaining the speed ratio i selected in step 5, and the power generation equal to the power generation required torque ΔT (= TTAL−TTNRAL) with the first MG2 as a generator. Control to output torque.
[0025]
If it is determined in step 20 that the power generation request torque ΔT exceeds the power generation possible torque Tmsoc, it is determined that the excessive torque of the engine 1 cannot be absorbed, and in step 22 the gear ratio i is shifted up by one step. Thus, the driving torque of the engine 1 is set to be reduced. For example, as shown in FIG. 6, the first MG 2 is generated in response to the power generation request and the battery 14 is charged. As a result, the amount of charge of the battery 14 becomes excessive and the power generation request torque ΔT cannot be obtained. The drive torque of the engine 1 is reduced to switch the first MG2 to the assist request.
[0026]
In step 23, the required drive torque TTNRAL when the engine 1 is operated so as to satisfy the required drive output TW at the gear ratio (i + 1) shifted up by one step, and the best when the engine 1 is operated to achieve the best fuel consumption. The fuel consumption driving torque TTAL is calculated.
The required drive torque TTNRAL becomes greater than the best fuel consumption drive torque TTAL due to the shift up and is switched when an assist request is made. In step 24, the assistable torque Tmsoc corresponding to the battery state of charge SOC is calculated, and in step 25 the assist is calculated. The required torque ΔT (= TTNRAL−TTAL) is calculated.
[0027]
In step 26, it is determined whether the assist request torque ΔT is equal to or less than the assistable torque Tmsoc. If it is determined that ΔT ≦ Tmsoc, it is determined that the first MG2 assist torque that covers the shortage of the drive torque of the engine 1 can be obtained. Then, the gear ratio (i + 1) is set in step 27 and the engine 1 is controlled to operate at the best fuel efficiency driving torque TTAL calculated in step 23, and the assist request torque calculated in step 25 is set using the first MG2 as an electric motor. Control is performed to output an assist torque equal to ΔT.
[0028]
If it is determined in step 26 that the assist request torque ΔT exceeds the assistable torque Tmsoc, the engine 1 is operated at the best fuel consumption drive torque TTAL calculated in step 23, and the first MG2 is used as a generator. Since the required drive output cannot be obtained even when the power is generated, the speed ratio (i + 1) is set at step 28, and the engine 1 is output as the required drive torque TTNRAL at the speed ratio (i + 1) while operating as the first MG2. To control. Alternatively, the engine 1 may be controlled to output the required drive torque TTNRAL at the gear ratio i while returning to the gear ratio i and operating the first MG2 as a generator. In either case, the engine 1 cannot be operated with the best fuel efficiency, but can be operated with the best possible fuel efficiency while satisfying the required drive output of the vehicle.
[0029]
According to the embodiment described above, the engine 1 and the first MG 2 as the travel drive source, the battery 14 that is charged and discharged between the first MG 2, and the stepped transmission disposed between the engine 1 and the drive wheels 7. 4, corresponding to the gear ratio i set in the stepped transmission 4 and means for calculating the required drive output TW of the vehicle (step 1 in FIG. 2). Then, a means for calculating a deviation ΔT between the required drive torque TTNNRAL when the engine 1 is operated so as to satisfy the required drive output TW and the best fuel efficiency drive torque TTAL when the fuel efficiency is optimized ( Steps 7, 13, 18, 24) of FIG. 2, means for detecting the state of charge SOC of the battery, and possible driving / regenerative torque of the first MG2 according to the state of charge of the battery Means for calculating msoc (steps 8, 14, 19, 25 in FIG. 2), deviation ΔT between required drive torque TTNRAL of engine 1 and best fuel consumption drive torque TTAL, and possible drive / regeneration of electric motor / generator Based on the torque Tmsoc, the engine 1, the first MG 2 and the stepped transmission 4 are controlled so as to obtain the required drive output TW of the vehicle while operating the engine 1 near the best fuel efficiency characteristic (α in FIG. 4). Means (steps 10, 16, 17, 21, 27, and 28 in FIG. 2).
[0030]
Thus, the gear ratio i is such that the deviation ∆T between the required drive torque TTNRAL and the best fuel efficiency drive torque TTAL can be covered by the first MG2 based on the possible drive / regenerative torque of the first MG2 corresponding to the state of charge SOC of the battery 14. Therefore, the required drive output TW of the vehicle can be obtained while the engine 1 is operated near the best fuel efficiency characteristic α.
[0031]
Specifically, a gear ratio i where the deviation ΔT between the required driving torque TTNRAL of the engine 1 and the best fuel efficiency driving torque TTAL is reduced is selected, and the torque deviation ΔT at the selected gear ratio i is selected as the possible drive / When it is determined based on the regenerative torque Tmsoc that the driving / regenerative torque of the first MG2 can cover it, the selected gear ratio i is set, and when it is determined that it cannot be covered, the driving / regenerative function of the first MG2 is switched. The gear ratio i is switched and set (i → i-1, i + 1), the engine 1 is driven with the best fuel consumption driving torque TTAL corresponding to the set gear ratio i, and the torque deviation ΔT is driven by the first MG2. The control is performed so that the required drive output TW is satisfied by covering with the regenerative torque.
[0032]
In addition, the engine 1 is calculated so as to satisfy the required drive output TW for each gear ratio i of the stepped transmission 4 so as to satisfy the required drive output TW, and the required drive output TW is satisfied. The engine speed TNAL when the fuel efficiency is optimized at an arbitrary speed ratio is calculated, and the speed difference between the engine speed TNGPi for each speed ratio i and the engine speed TNAL at the best fuel efficiency is minimized. Since the gear ratio in the driving (3rd speed in the example of FIG. 4) is the gear ratio to be selected first, the gear ratio with the smallest deviation ΔT can be calculated easily and accurately.
[0033]
When the required drive torque TTNRAL of the engine 1 is greater than the best fuel consumption drive torque TTAL and the difference is greater than the possible drive torque Tmsoc of the first MG2 corresponding to the state of charge SOC of the battery 14, the gear ratio i is shifted down ( i → i-1), the driving torque of the engine 1 is increased, and the battery 14 is charged while generating the regenerative torque by generating the first MG2, so that the engine 1 is driven at the best fuel efficiency by downshifting. be able to.
[0034]
Further, when the best fuel consumption driving torque TTAL of the engine 1 is larger than the required driving torque TTNRAL and the difference is larger than the possible regenerative torque Tmsoc of the first MG2 corresponding to the state of charge SOC of the battery 14, the gear ratio i is shifted up ( i → i + 1) to reduce the driving torque of the engine 1 and discharge the battery 14 to drive the first MG 2 to obtain the driving torque, so that the engine 1 can be operated with the best fuel consumption by upshifting. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a drive transmission system of a vehicle including a hybrid powertrain control device according to an embodiment of the present invention. FIG. 2 is a flowchart (first stage) of drive control according to the embodiment.
FIG. 3 is a flowchart (second stage) of drive control according to the embodiment.
FIG. 4 is a diagram showing a state when various values are calculated according to the embodiment.
FIG. 5 is a diagram showing a state when switching from an assist request to a power generation request according to the embodiment;
FIG. 6 is a diagram showing a state when switching from a power generation request to an assist request according to the embodiment;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... 1st MG 4 ... Transmission 7 ... Rear wheel 21 ... Hybrid control module 32 ... Motor controller 33 ... Motor controller

Claims (5)

An internal combustion engine and an electric / generator as a traveling drive source, a battery that is charged / discharged between the electric / generator, and a stepped transmission that is disposed between the engine and drive wheels. In the hybrid powertrain for vehicles
Means for calculating the required drive output of the vehicle;
Corresponding to the gear ratio set by the stepped transmission, the best fuel efficiency driving when the required driving torque and the fuel efficiency when the internal combustion engine is operated to satisfy the required driving output is the best. Means for calculating a deviation from the torque;
Means for detecting the state of charge of the battery;
Means for calculating possible drive / regenerative torque of the electric / generator according to the state of charge of the battery;
When it is determined that the deviation between the required drive torque of the internal combustion engine and the best fuel efficiency drive torque cannot be covered by the drive / regenerative torque of the electric / generator according to the state of charge of the battery, the gear ratio of the stepped transmission Means for switching the gear ratio so that the torque deviation at the time of switching is covered by the drive / regenerative torque of the electric motor / generator according to the state of the battery ;
A control apparatus for a hybrid powertrain for a vehicle, comprising: A gear ratio that reduces the deviation between the required drive torque of the internal combustion engine and the best fuel efficiency drive torque is selected, and the deviation of the torque at the selected gear ratio is determined based on the possible drive / regenerative torque / When it is determined that it can be covered by regenerative torque, it is set to the selected gear ratio, and when it is determined that it cannot be covered, the gear ratio is switched and set so that the drive / regenerative function of the motor / generator is switched, The internal combustion engine is driven with the best fuel efficiency driving torque corresponding to the set gear ratio, and the torque deviation is controlled by the electric / generator driving / regenerative torque so as to satisfy the required driving output. The control apparatus for a hybrid powertrain for a vehicle according to claim 1 . The engine rotational speed when the internal combustion engine is operated to satisfy the required drive output for each gear ratio of the stepped transmission is calculated, and the fuel efficiency is satisfied at an arbitrary speed ratio while satisfying the required drive output. The engine speed when the engine is operated so as to be the best is calculated, and the speed ratio in the operation where the speed difference between the engine speed for each speed ratio and the engine speed at the best fuel consumption is minimized is calculated as the internal combustion engine. 3. The control apparatus for a hybrid powertrain for a vehicle according to claim 2 , wherein the transmission ratio is such that the deviation between the required drive torque and the best fuel efficiency drive torque is small . When the required drive torque of the internal combustion engine is greater than the best fuel consumption drive torque and the difference is greater than the possible drive torque of the electric / generator according to the state of charge of the battery, the gear ratio is shifted down to drive the internal combustion engine. 4. The control device for a hybrid powertrain for a vehicle according to claim 2, wherein the battery is charged while increasing torque and generating electric motor / generator to obtain regenerative torque. When the best fuel efficiency drive torque of the internal combustion engine is larger than the required drive torque and the difference is larger than the possible regenerative torque of the electric motor / generator according to the state of charge of the battery, the gear ratio is shifted up to drive the internal combustion engine. The hybrid powertrain control for a vehicle according to any one of claims 2 to 4 , wherein the torque is reduced and the battery is discharged to drive the motor / generator to obtain a driving torque. apparatus.

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