JP2014172564A - Hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a torque variation of a drive axle in a hybrid vehicle, and prevent a fuel consumption of an engine from increasing unnecessarily.SOLUTION: When an engine (2) is started, control means (16) calculates a target torque for motor generators (4 and 5) so that an engine speed is equal to a target engine speed designated by target engine running point designation means (16C). The control means includes change means (16D) that changes a target torque calculation feedback gain for the motor generators (4 and 5) according to the warmup state of the engine (2) discriminated by engine warmup state discrimination means (16A).

Description

  The present invention relates to a hybrid vehicle, and more particularly, to a hybrid vehicle that controls a power source at start-up in a vehicle including a plurality of power sources.

Conventionally, as a vehicle, there is a hybrid vehicle that outputs, as a plurality of power sources, power generated from an engine and a plurality of motor generators (generators) to a drive shaft via a power transmission mechanism.
As such hybrid vehicles, there are the following prior art documents.

Japanese Patent No. 3931854 Japanese Patent No. 3890459

The power output device, the control method thereof, and the automobile according to Patent Document 1 use a feedback of the first gain to operate the engine at a target operating point until a predetermined time has elapsed since the engine was started. After a predetermined time has elapsed, the motor generator is controlled using feedback of a second gain different from the first gain. Thus, immediately after the start when the behavior of the engine is unstable, a large correction torque is not output from the motor generator to the engine, and the torque requested by the driver is appropriately output.
In the engine automatic stop / restart vehicle according to Patent Document 2, the first feedback gain is set in the first period until the engine enters the stable combustion state, and in the second period after the engine shifts to the stable combustion state. Switches to a second feedback gain smaller than the first feedback gain.

However, in Patent Document 1 described above, there is no mention of a “predetermined time” setting method for switching between the first gain and the second gain. If this “predetermined time” is set longer, fluctuations in the torque of the drive shaft can be reliably prevented, but on the other hand, the first gain is set smaller than the second gain. It becomes difficult to operate with.
Since the operating point of the engine is set as the point where the efficiency of the entire system including the engine and the motor generator is the best, the fact that the engine cannot be operated at the target driving point leads to deterioration in fuel consumption.
Therefore, in order to prevent fluctuations in the torque of the drive shaft and prevent the fuel consumption from deteriorating by operating the engine at the target operating point, it is necessary to optimally set the “predetermined time” described above, and improvement is desired. It was.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a hybrid vehicle that prevents torque fluctuations of a drive shaft and prevents an increase in engine fuel consumption more than necessary.

  The present invention relates to an engine warm-up state determining means for determining a warm-up state of the engine in a hybrid vehicle that outputs the power generated from the engine and the motor generator to a drive shaft via a power transmission mechanism, and a driver's request. The target engine power and the target charge / discharge power are calculated so that the required driving force set by the required driving force setting means can be output, and the target engine power is calculated. A control means comprising a target engine operating point setting means for calculating a target engine operating point based on the power and setting a target engine rotational speed and a target engine torque from the calculated target engine operating point is provided. The means is a target in which the engine speed is set by the target engine operating point setting means when the engine is started. The target torque of the motor generator is calculated so that the engine rotational speed is reached, and the feedback gain for calculating the target torque of the motor generator is changed according to the engine warm-up state determined by the engine warm-up state determination means It is characterized by having a change means to do.

  The present invention makes it possible to prevent fluctuations in the torque of the drive shaft and not increase the fuel consumption of the engine more than necessary.

FIG. 1 is a system configuration diagram of a control apparatus for a hybrid vehicle. (Example) FIG. 2 is a block diagram of control of the hybrid vehicle. (Example) FIG. 3 is a flowchart for calculating the target motor torque. (Example) FIG. 4 shows a target drive torque search map. (Example) FIG. 5 shows a target charge / discharge power search table. (Example) FIG. 6 is a diagram showing a target operating point map. (Example) FIG. 7 is a view showing a starting target engine torque search map. (Example) FIG. 8 is a collinear diagram according to the embodiment of the present invention. (Example) FIG. 9 is a diagram showing temporal changes in the normal feedback gain. (Example) FIG. 10 is a diagram showing a feedback gain switching ratio search table. (Example)

  The present invention realizes the purpose of preventing fluctuations in the torque of the drive shaft and not increasing the fuel consumption of the engine more than necessary by changing the feedback gain for calculating the target torque of the motor generator according to the warm-up state of the engine. To do.

1 to 10 show an embodiment of the present invention.
As shown in FIG. 1, a power source control device 1 is mounted on a hybrid vehicle (hereinafter referred to as “vehicle”).
The control device 1 includes an output shaft 3 of an engine (also referred to as “ENG” in the drawing) 2 that is a power source that outputs torque, and a first motor generator (in the drawing, as a motor generator). A drive shaft (shown as “MG1”) 4 and a second motor generator (also indicated as “MG2” in the drawing) 5 and an output member connected to the drive wheels 6 via an output transmission unit 7 The power transmission mechanism (differential gear mechanism) connected to the output shaft 3 of the engine 2, the first motor generator 4, the second motor generator 5, and the drive shaft 8 respectively. 9).
The first motor generator 4 includes a first rotor 10 and a first stator 11. The second motor generator 5 includes a second rotor 12 and a second stator 13.
As shown in FIGS. 1 and 2, the control device 1 includes a first inverter 14 that controls the operation of the first motor generator 4, and a second inverter 15 that controls the operation of the second motor generator 5. The control means (ECU) 16 connected to the first inverter 14 and the second inverter 15 is provided.
The first inverter 14 is connected to the first stator 11 of the first motor generator 4. The second inverter 15 is connected to the second stator 13 of the second motor generator 5.
Each power terminal of the first inverter 14 and the second inverter 15 is connected to a battery (drive high voltage battery) 17. The battery 17 can exchange power with the first motor generator 4 and the second motor generator 5.
In the control device 1, the hybrid vehicle is driven and controlled using outputs from the engine 2, the first motor generator 4, and the second motor generator 5.

The power transmission mechanism 9 is a so-called four-shaft power input / output device, which includes the output shaft 3 and the drive shaft 8 of the engine 2, and the first motor generator 4 on the engine 2 side and the drive shaft 8 side. The second motor generator 5 is arranged, the power of the engine 2, the power of the first motor generator 4 and the power of the second motor generator 5 are combined and output to the drive shaft 8, and the engine 2 and the second motor generator 5 are combined. Power is exchanged among one motor generator 4, second motor generator 5, and drive shaft 8.
That is, in the power transmission mechanism 9, four elements including the engine 2, the first motor generator 4, the second motor generator 5, and the drive shaft 8 as an output member are shared as shown in FIG. On the diagram, the first motor generator (MG1) 4, the engine (ENG) 2, the drive shaft (OUT) 8 as an output member, and the second motor generator (MG2) 5 are connected in this order, and a gear mechanism. Is configured.

The power transmission mechanism 9 is configured by arranging a first planetary gear mechanism 18 and a second planetary gear mechanism 19 in which two rotating elements are connected to each other.
The first planetary gear mechanism 18 includes a first sun gear 20, a first pinion gear 21 that meshes with the first sun gear 20, and a first ring gear 22 that meshes with the first pinion gear 21. The first carrier 23 connected to the first pinion gear 21 and the output gear 24 connected to the first ring gear 22 are provided.
The second planetary gear mechanism 19 includes a second sun gear 25, a second pinion gear 26 meshed with the second sun gear 25, and a second ring gear 27 meshed with the second pinion gear 26. And a second carrier 28 connected to the second pinion gear 26.

In the power transmission mechanism 9, the first carrier 23 of the first planetary gear mechanism 18 is connected to the output shaft 3 of the engine 2. The second carrier 28 of the second planetary gear mechanism 19 is connected to the first ring gear 22 and the output gear 24 of the first planetary gear mechanism 18.
The first rotor 10 of the first motor generator 4 is connected to the first sun gear 20 via the first motor output shaft 29. The output shaft 3 of the engine 2 is connected to the first carrier 23 and the second sun gear 25. The drive shaft 8 is connected to the first ring gear 22 and the second carrier 28 via the output gear 24 and the output transmission unit 7. The second rotor 12 of the second motor generator 5 is connected to the second ring gear 27 via the second motor output shaft 30.
The second motor generator 5 includes a second motor output shaft 30, a second ring gear 27, a second carrier 28, a first ring gear 22, an output gear 24, the output transmission unit 7, and the drive shaft 8. Thus, the vehicle can be directly connected to the drive wheel 6 and the vehicle is driven only by a single output.
That is, in the power transmission mechanism 9, the first carrier 23 of the first planetary gear mechanism 18 and the second sun gear 25 of the second planetary gear mechanism 19 are coupled and connected to the output shaft 3 of the engine 2. The first ring gear 22 of the first planetary gear mechanism 18 and the second carrier 28 of the second planetary gear mechanism 19 are coupled and connected to the drive shaft 8, and the first planetary gear mechanism 18 The first motor generator 4 is connected to one sun gear 20, the second motor generator 5 is connected to the second ring gear 27 of the second planetary gear mechanism 19, the engine 2, the first motor generator 4, Power is exchanged between the second motor generator 5 and the drive shaft 8.

  As shown in FIG. 2, the control means 16 includes an accelerator opening degree detecting means 31 for detecting the depression amount of the accelerator pedal as an accelerator opening degree, an engine rotation speed detecting means 32 for detecting the rotation speed of the engine 2, and an engine. A water temperature detecting means 33 for detecting the coolant temperature of the engine 2 as the engine water temperature, a vehicle speed detecting means 34 for detecting the vehicle speed as the speed of the vehicle, and a charging state detecting means 35 for detecting the state of charge (SOC) of the battery 17. Connected.

As shown in FIG. 2, the control unit 16 includes an engine warm-up state determination unit 16A, a required driving force setting unit 16B, and a target engine operating point setting unit 16C.
The engine warm-up state determination unit 16A receives the output signal from the water temperature detection unit 33 and determines the warm-up state of the engine 2.
The requested driving force setting means 16B sets the requested driving force according to the driver's request.
The target engine operating point setting unit 16C calculates the target engine power and the target charge / discharge power so that the required driving force set by the required driving force setting unit 16B can be output, and the target engine operation based on the target engine power. A point is calculated, and a target engine speed and a target engine torque are set from the calculated target engine operating point.
Moreover, the control means 16 is provided with the change means 16D, as shown in FIG.
The changing means 16D calculates the target torque of the motor generators 4 and 5 so that the engine speed becomes the target engine speed set by the target engine operating point setting means 16C when the engine 2 is started. The target torque calculation feedback gains 4 and 5 are changed according to the warm-up state of the engine 2 determined by the engine warm-up state determination means 16A.
The warm-up state of the engine 2 is determined by an output signal from the water temperature detecting means 33 that detects the coolant temperature of the engine 2 as the engine water temperature.

Next, control according to this embodiment will be described based on the flowchart of FIG.
In the flowchart of FIG. 3, a method for calculating the target motor torque for making the engine rotational speed coincide with the target rotational speed will be described.
As shown in FIG. 3, when the program of the control means 16 is started (step A01), first, as various signals used for control, the accelerator opening, the vehicle speed, the state of charge of the battery 17 (SOC), the engine water temperature, the engine The rotational speed is captured (step A02).
And the target drive torque according to a vehicle speed and an accelerator opening is calculated from the target drive torque search map shown in FIG. 4 (step A03). The high vehicle speed range at the accelerator opening = 0 is set to a negative value so that the driving torque in the deceleration direction corresponding to the engine brake is obtained. On the other hand, in the region where the vehicle speed is low, a positive value is set so that creep driving can be performed. Value.
Thereafter, the target drive power calculated to drive the vehicle is calculated by multiplying the target drive torque calculated in step A03 by the vehicle speed (step A04).
Then, in order to control the state of charge (SOC) of the battery 17 within the normal use range, the target charge / discharge amount is calculated from the target charge / discharge power search table shown in FIG. 5 (step A05). Here, as shown in FIG. 5, when the state of charge (SOC) of the battery 17 is low, the target charge / discharge power is increased to prevent overdischarge of the battery 17, while the state of charge of the battery 17 is When (SOC) is high, the target charge / discharge power is increased to prevent overcharging of the battery 17. In FIG. 5, for convenience, the discharge side is treated as a positive value (+) and the charge side is treated as a negative value (−).
And the target engine power which the engine 2 should output from the said target drive power and the said target charging / discharging power is calculated (step A06). The target engine power to be output by the engine 2 is a value obtained by adding the target charging / discharging power for charging / discharging the battery 17 to the target driving power necessary for driving the vehicle. Here, since the charge side is handled as a negative value (−), the target engine power is calculated by subtracting the target charge / discharge power from the target drive power.

Thereafter, it is determined whether or not the engine 2 has been started (step A07). In this embodiment, for example, it is determined that the engine 2 is started when the engine torque is equal to or greater than a predetermined value and the engine rotation speed is equal to or greater than a predetermined value.
If this step A07 is YES and the engine 2 has been started, a target engine operating point is calculated (step A08).
In step A08, the target operating point map of FIG. 6 is searched from the target engine power calculated in step A06, and the target engine operating point (target engine speed, target engine torque) is calculated.
As shown in FIG. 6, this target operating point map is obtained from a power transmission system constituted by a power transmission mechanism 9, a first motor generator 4, and a second motor generator 5 for engine efficiency on an equal power line. The line that selects and connects the points where the overall efficiency with the highest efficiency is selected for each power is set as the target operation line. Therefore, the intersection of the target engine power and the target operation line becomes the target engine operating point (target engine speed, target engine torque).

On the other hand, if step A07 is NO and the engine 2 has not been started, a starting target engine operating point is calculated (step A09).
In step A09, a starting target engine operating point (target engine speed, target engine torque) for engine starting is calculated.
The starting target engine torque is calculated from the starting target engine torque search map shown in FIG. If the starting target engine torque is set to a minus (−) side from the friction torque at the time of fuel cut of the engine 2, the target motor torque base calculated in step A 10 described later can overcome the friction of the engine 2. The engine speed can be increased. Further, the target engine speed at start is set to 1000 rpm or the like.

After the process of step A08 or after the process of step A09, a target motor torque base is calculated from the calculated target drive power, target engine power, and target engine operating point (step A10).
In this embodiment, the following (Expression 1) representing the balance of torque input to the power transmission mechanism 9 and the power generated or consumed by the first motor generator 4 and the second motor generator 5 and the battery 17 are shown. The target MG1 (first motor generator) torque base and the target MG2 (second motor generator) torque base calculated from the calculation results of the simultaneous equations consisting of Let the minutes be the target motor torque base. When the engine is started, the target motor torque base is calculated with the target engine torque set larger than the friction torque at the time of fuel cut of the engine 2 to the minus (−) side. Therefore, the first motor generator 4 and the second motor The torque output from the generator 5 can overcome the friction of the engine 2 and increase the engine speed.

Target engine torque + (1 + k1) × target MG1 torque base portion = k2 × target MG2 torque base portion (Expression 1)
k1: MG1-ENG lever ratio with ENG-OUT as 1 in FIG. 8 k2: OUT-MG2 lever ratio with ENG-OUT as 1 in FIG. 8 Target drive power-target engine power = MG1 rotational angular velocity × Target MG1 torque base + MG2 rotation angular velocity x Target MG2 torque base ... (Formula 2)

Thereafter, similarly to Step A07, it is determined whether or not the engine 2 has been started (Step A11). In this embodiment, it is determined that the engine 2 is started when the engine torque is equal to or greater than a predetermined value and the engine speed is equal to or greater than the predetermined value.
If this step A11 is YES and the engine 2 has been started, a normal feedback gain is calculated (step A12).
In step A12, a feedback gain for setting the engine rotation speed to the target rotation speed is set. As shown in FIG. 9, the feedback gain is set so as to gradually switch from the feedback gain for starting the engine to the normal feedback gain different from the feedback gain for starting the engine. Further, as the feedback gain switching ratio, the ratio calculated from the feedback gain switching ratio search table (see FIG. 10) according to the engine water temperature, which is an index indicating whether or not the engine 2 is in the cold state, is used. As a result, in a fully warm state where the behavior of the engine 2 is relatively stable, the feedback gain is quickly switched to give priority to improving the followability of the engine speed to the target rotational speed, while the behavior of the engine 2 is more unstable. In the cold state, the feedback gain switching is delayed to suppress large correction by the first motor generator 4 and the second motor generator 5 immediately after the engine 2 is started, and the torque fluctuation of the drive shaft 8 is surely reduced. To prevent. Further, since the feedback gain is gradually switched from start to normal, the target motor torque feedback is not suddenly switched stepwise, and sudden change in the torque of the drive shaft 8 can be prevented. .

On the other hand, if step A11 is NO and the engine 2 has not been started, a starting feedback gain is calculated (step A13).
In step A13, as shown in FIG. 9, the feedback gain for starting the engine is set to a value smaller than the feedback gain for normal use, so that the first immediately after the start of the engine 2 where the behavior of the engine 2 is unstable. Thus, the motor generator 4 and the second motor generator 5 do not apply a large correction, and the torque fluctuation of the drive shaft 8 can be prevented.

After the process of step A12 or after the process of step A13, a target motor torque feedback component (target MG1 torque feedback component, target MG2 torque feedback component) for making the engine rotation speed coincide with the target rotation speed is calculated ( Step A14).
The target MG1 torque feedback is obtained from the engine rotational speed and the target engine rotational speed using the following equation (3), and the target MG2 torque feedback is obtained using the following equation (4) in consideration of the torque balance. .

Target MG1 torque feedback = (target engine rotational speed−engine rotational speed) × feedback gain (Equation 3)
k1 × target MG1 torque feedback = (1 + k2) × target MG2 torque feedback (Equation 4)
k1: Lever ratio of MG1-ENG where ENG-OUT is 1 in FIG. 8 k2: Lever ratio of OUT-MG2 where ENG-OUT is 1 in FIG.

Then, the first motor generator 4 and the second motor generator 5 are controlled using the sum of the target motor torque base and the target motor torque feedback as the target motor torque (step A15).
Thereafter, the program is returned (step A16).

That is, in this embodiment, in a hybrid vehicle that includes the engine 2 and the motor generators 4 and 5 as power sources and performs feedback control with the motor generators 4 and 5 so that the engine rotational speed matches the target rotational speed, The change to the feedback gain is gradually switched at a predetermined rate. Further, in a hybrid vehicle that includes the engine 2 and the motor generators 4 and 5 as power sources and performs feedback control with the motor generators 4 and 5 so that the engine rotation speed matches the target rotation speed, the rate of change to the normal feedback gain is set. Change according to engine water temperature.
With such a configuration, the feedback gain switching timing can be changed in accordance with the warm-up state of the engine 2. Therefore, in the complete warm state where the behavior of the engine 2 is relatively stable, the target engine speed immediately after the engine 2 is started. While it is possible to improve the follow-up performance with respect to the rotational speed, in the cold state where the behavior of the engine 2 becomes unstable, the large correction by the motor generators 4 and 5 with respect to the engine 2 is suppressed immediately after the engine 2 is started. Torque fluctuations of the drive shaft 8 can be prevented. In addition, since the change to the normal feedback gain is gradually switched, the motor torque does not change stepwise, and a sudden change in the torque of the drive shaft 8 can be prevented.

Although the embodiments of the present invention have been described above, the configuration of the above-described embodiments will be described for each claim.
First, in the first aspect of the present invention, when the engine 2 is started, the control means 16 sets the motor generator 4, so that the engine speed becomes the target engine speed set by the target engine operating point setting means 16 C. And a change means 16D for changing the target torque calculation feedback gain of the motor generators 4 and 5 according to the warm-up state of the engine 2 determined by the engine warm-up state determination means 16A. Yes.
With such a configuration, the feedback gain for calculating the target torque of the motor generators 4 and 5 can be changed according to the warm-up state of the engine 2, so that the torque fluctuation of the drive shaft 8 is prevented and the fuel consumption of the engine 2 is reduced. Is not increased more than necessary.
In the second aspect of the invention, the warm-up state of the engine 2 is determined by an output signal from the water temperature detection means 33 that detects the coolant temperature of the engine 2 as the engine water temperature.
This eliminates the need for a special calculation method or special detection means, and simplifies the configuration.

  The control device according to the present invention can be applied to various vehicles.

1 Controller 2 Engine (ENG)
3 Engine output shaft 4 First motor generator (MG1)
5 Second motor generator (MG2)
6 Drive wheel 8 Drive shaft (OUT)
9 Power transmission mechanism (differential gear mechanism)
16 Control means (ECU)
16A Engine warm-up state determining means 16B Required driving force setting means 16C Target engine operating point setting means 16D Changing means 17 Battery 18 First planetary gear mechanism 19 Second planetary gear mechanism 31 Accelerator opening degree detecting means 32 Engine rotational speed detection Means 33 Water temperature detection means 34 Vehicle speed detection means 35 State of charge (SOC) detection means

Claims (2)

  In a hybrid vehicle that outputs power generated from an engine and a motor generator to a drive shaft via a power transmission mechanism, engine warm-up state determining means for determining a warm-up state of the engine, and requested according to a driver's request The target engine power and the target charge / discharge power are calculated so that the required driving force setting means for setting the driving force and the required driving force set by the required driving force setting means can be output, and based on the target engine power Control means comprising target engine operating point setting means for calculating a target engine operating point and setting a target engine rotational speed and target engine torque from the calculated target engine operating point is provided. The target engine speed whose engine speed is set by the target engine operating point setting means when the engine is started A change in which the target torque calculation feedback gain of the motor generator is changed according to the engine warm-up state determined by the engine warm-up state determination means A hybrid vehicle characterized by comprising means.   2. The hybrid vehicle according to claim 1, wherein the warm-up state of the engine is determined by an output signal from a water temperature detecting unit that detects a cooling water temperature of the engine as an engine water temperature.

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