JP2006183523A - Drive force control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce PM, NOx emission of a hybrid vehicle at a time of atmospheric pressure drop. <P>SOLUTION: Motor output ratio under a heavy load condition is increased at the time of atmospheric pressure drop as compared to a normal time and engine output ratio is reduced to reduce PM, NOx emission and boundary output at a time of motor travel completion is made small as compared to the normal time and travel output is generated by the engine and the motor is driven as a generator by surplus output to charge a battery. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for controlling driving force of an engine and a motor in a hybrid vehicle.

In Patent Document 1, in a hybrid vehicle using an engine and a motor as a driving force source, the engine driving force is transmitted to the wheels when it is determined that the vehicle is in a high speed traveling region, and the engine is transmitted when it is determined that the vehicle is in a low / medium speed traveling region. An apparatus is disclosed which is controlled so as to prohibit transmission of driving force to wheels.
JP-A-6-225403

As in the above-mentioned Patent Document 1, if the system mainly uses the engine driving force in the high load region and mainly uses the motor driving force in the low load region, the exhaust purification performance and the fuel consumption performance can be maintained well. .
However, especially in a diesel engine, when the atmospheric pressure decreases during high altitude travel, as shown in FIG. 12, it is difficult to ensure a sufficient amount of air at high loads, and the air charging efficiency decreases. For this reason, if the EGR amount is corrected to decrease so as not to change the intake air amount with respect to the normal atmospheric pressure (during lowland travel), the NOx emission amount increases due to a decrease in the EGR rate. Conversely, if the EGR rate is kept constant, the amount of intake air decreases with respect to the same load (fuel injection amount), so that the amount of exhaust particulate (hereinafter referred to as PM) emission increases.

If both the intake air amount and the EGR rate are lowered in the middle, NOx and PM are deteriorated accordingly, and the NOx and PM exhaust amount cannot be reduced well at the same time.
When the load is low, as shown in FIG. 13, a sufficient amount of air is ensured even if the atmospheric pressure decreases with respect to a small amount of fuel, and the exhaust flow rate (absolute amount) may decrease. Both NOx emissions can be kept low enough.

  In order to solve the above-mentioned problems, the present invention increases the ratio of the motor driving force when the driving force calculating means for calculating the driving force of the engine and the motor detects a decrease in the atmospheric pressure compared to the normal case. To calculate.

  With such a configuration, when the atmospheric pressure decreases, the motor driving force ratio increases from the normal time, and the engine driving power ratio decreases relatively, so that the NOx and PM emissions can be reduced to the normal level. .

FIG. 1 schematically shows a drive control apparatus for a hybrid vehicle according to an embodiment of the present invention.
An exhaust treatment device 1a made of a catalyst or the like is attached to the exhaust passage of the engine (internal combustion engine) 1, and the gear ratio is variably controlled by changing the input / output pulley diameter ratio on the output shaft of the engine 1 The first continuously variable transmission 2 is connected, and the output shaft (output pulley shaft) of the continuously variable transmission 2 is connected to one end of the gear shaft 4 via the first clutch 3.

The gear 4a of the gear shaft 4 meshes with a gear 5a fixed to an axle (drive shaft) 5 having wheels connected to both ends, and the engine driving force is applied to the first continuously variable transmission 2 and the first clutch. 3. It is transmitted to the axle 5 via the gear 4a and the gear 5a.
The engine 1 and the first continuously variable transmission 2 are controlled by an engine control device 6.

  On the other hand, a battery 13 is connected to the motor 11 via an inverter 12. When the motor 11 functions as an electric motor, electric power is supplied from the battery 13. When the motor 11 functions as an electric generator, electric power generated Is charged in the battery 13. A second continuously variable transmission 14 having a function similar to that of the first continuously variable transmission 2 is connected to the output shaft of the motor 11, and the output shaft (output pulley shaft) of the continuously variable transmission 14 is The other end of the gear shaft 4 is connected via a second clutch 15.

The motor 11 and the second continuously variable transmission 14 are controlled by a motor control device 16.
The hybrid controller 17 receives an accelerator opening signal (driver request signal) from the accelerator opening sensor 21 and a vehicle speed signal from the vehicle speed sensor 22, and basically, based on these signals, the vehicle's speed signal. The required driving force is calculated, and the output ratio (driving force ratio) between the engine 1 and the motor 11 is determined according to the required driving force (required total required output of the engine and motor).

  Here, as a configuration according to the present invention, when a low atmospheric pressure state is detected, such as when traveling at high altitude, the output ratio of the motor 11 is increased and the output ratio of the engine is decreased as compared with normal (low altitude) traveling. To correct. In order to detect the atmospheric pressure, a pressure sensor 23 for detecting the intake collector pressure is provided to detect the intake collector pressure as an atmospheric pressure under a predetermined condition such as a low speed. In addition, the atmospheric pressure is detected according to the air density obtained from the relationship between the mass intake air flow rate detected by the air flow meter and the volume intake air flow rate estimated from the throttle opening, the engine speed, and the like. Atmospheric pressure can be estimated.

Further, when the charge amount of the battery 13 is detected and the charge amount is too low, the increase correction of the motor 11 output ratio is prohibited.
Then, the required outputs of the engine 1 and the motor 11 are calculated according to the output ratio determined in this way, and the engine output and the motor output are calculated via the engine control device 6 and the motor control device 16 according to each target output. Control (see FIG. 2).

Hereinafter, the distribution control between the engine output and the motor output by the hybrid control device 17 will be described in more detail based on the flowcharts of FIG.
FIG. 3 shows the main flow.
In step (denoted as S in the figure, the same applies hereinafter) 1, detected values from the respective sensors are input to detect the operating state.

In step 2, based on the detected driving state, an output distribution map for normal (lowland travel) (see FIG. 5) and an output distribution map for atmospheric pressure drop (highland travel) (see FIG. 6) Select one of the following.
Details of the map selection will be described based on the flowchart of FIG.
In step 11, it is determined whether the atmospheric pressure Pex detected by the pressure sensor 23 is lower than the pressure boundary value Pexb. If it is determined that the pressure boundary value Pexb is greater than or equal to the pressure boundary value Pexb, the process proceeds to step 14 and the normal output distribution is performed. Select a map.

On the other hand, when it is determined in step 11 that the atmospheric pressure Pex is lower than the pressure boundary value Pexb, the process proceeds to step 12 to determine whether the battery charge amount SOC is larger than the charge amount boundary value Lb. When it is determined, the process proceeds to step 13 to select an output distribution map for when the atmospheric pressure drops.
Further, when it is determined in step 12 that the battery charge amount SOC is equal to or less than the charge amount boundary value Lb, the process proceeds to step 14 and an output distribution map for normal time is selected.

In other words, when the atmospheric pressure drops, there is a request to switch to a control that increases the motor output distribution than usual, but when the battery charge is not enough, it is impossible, so if the charge is sufficient Then, the output distribution map for when the atmospheric pressure drops is selected, and the control is switched to the control for making the output distribution of the motor larger than normal.
As shown in FIG. 5, the normal-time output distribution map shows that the motor 11 is in a low output range where the total required output (vehicle required driving force) P, which is a combination of the engine output and the motor output, is less than or equal to the boundary output Pbm0. Only when the motor driving boundary output Pbm0 is exceeded, the engine 1 is switched to driving only (engine output ratio 100%), and the total required output P becomes equal to or higher than the engine boundary output Peb0. Then, the engine output is held at a constant boundary output Peb0, and the output is distributed so that the output obtained by subtracting the engine boundary output Peb0 from the total required output P is covered by the motor output (= P-Peb0). That is, the engine 1 is operated only in a region where the fuel efficiency is the highest and the exhaust purification performance is excellent, and the motor 11 assists the shortage output.

  On the other hand, as shown in FIG. 6, the output distribution map for when the atmospheric pressure is reduced has a motor output ratio of 100% in the low output region where the total output P is lower than the boundary output Pmb1 lower than the normal motor traveling boundary output Pmb0. When the total required output P is set and exceeds the boundary output Pmb1 of the motor 11, the engine output is switched to the engine boundary output Peb1 larger than the motor boundary output Pmb1, and is controlled to be constant. Here, the boundary output Peb1 of the engine 1 when the atmospheric pressure drops is set to be smaller than the engine boundary output Peb0 of the normal time. In the region where the total output P is less than or equal to the engine boundary output Peb1, the excess output (= Peb1-P) of the boundary output Peb1 with respect to the total required output P is driven using the motor 11 as a generator to generate a negative output. To do so. When the total required output P exceeds the boundary output Peb1 of the engine, the shortage output is covered by the motor 11 as usual.

Returning to FIG. 3, in step 3, the engine output Pe and the motor output Pm are calculated from the total output P using the output distribution map selected in step 2 (flow of FIG. 4).
In step 4, for the calculated engine output Pe, from the operating point map shown in FIG. 7, the target engine speed Ne0 (normal time), Ne1 (normal pressure drop), and target torque Te0 (normal time) of the engine 1 are calculated. , Te1 (at the time of atmospheric pressure drop) is set and output to the engine control device 6. This driving point map is set so that fuel consumption and exhaust purification performance can be maintained satisfactorily. Further, the target gear ratio of the first continuously variable transmission 2 is changed so as to keep the vehicle speed constant in accordance with the change of the target rotational speed Ne of the engine. When the engine output ratio = 0 in the low output region where only the motor 11 is driven, the first clutch 3 is disconnected and the transmission of the engine output to the axle 4 is cut off. FIG. 8 shows the relationship between the rotational speed of the engine 1 and the torque at the engine operating point.

  In step 5, from the operating point map (not shown) set in the same manner as the engine operating point map for the calculated motor output Pm, the target rotational speed Nm0 (normal time) and Nm1 (atmospheric pressure drop) of the motor 11 are set. ), Target torque Tm0 (normal time), Nm1 (at the time of atmospheric pressure drop). This operating point map is also set so as to maintain good power consumption. Further, in accordance with the change of the target rotational speed Nm of the motor, the target speed ratio of the second continuously variable transmission 14 is changed so as to maintain the vehicle speed constant, and in the output region where only the engine 1 is driven, When the motor output ratio = 0, the second clutch 15 is disengaged and the transmission of the engine output to the axle 4 is cut off as in the case of engine control. FIG. 9 shows the relationship between the rotational speed of the motor 11 and the torque at the motor operating point.

  Here, when the set target rotational speed Nm and the target torque Tm are output to the motor control device 16 as they are to control the motor 11 (or simply, this may be sufficient), the motor 11 is compared with the engine 1. Since the control response is good and the convergence to the target value is fast, the total output changes transiently. When the motor 11 functions as an electric motor, the output is excessive, and when the motor 11 functions as a generator, the output is insufficient.

Therefore, as shown in FIG. 10, the motor output command value (target value) is output with a delay with respect to the engine output command value (target value). As a result, the output ratio can be switched while suppressing fluctuations in the total output P, which is a combination of the engine output and the motor output.
FIG. 11 shows changes in various state quantities during control according to the embodiment. If the atmospheric pressure decreases as the altitude increases during climbing and falls below the pressure boundary value Pexb, the output distribution map at the normal time is switched to the output distribution map when the atmospheric pressure decreases, and the output distribution of the motor 11 increases. .

When the map is switched, the output of the motor 11 is increased and the power consumption is increased. When the charge amount SOC of the battery 14 is reduced to the set value Lb or less (t2), the output is returned to the normal output distribution map. Output distribution decreases.
As a result, when the power consumption of the motor 11 is reduced and the battery charge SOC returns to the set value Lb or more (t3), the output distribution map is switched again when the atmospheric pressure decreases. In addition, the deceleration operation is performed before the map is switched. During this deceleration, the engine output is 0 and the motor 11 functions as a generator to generate a negative output with respect to the negative vehicle drive output (total output). At the same time, the battery 14 is fully charged.

When the deceleration operation is finished and the operation is switched to the acceleration operation, the vehicle drive output becomes a positive output, and the engine output and the motor output are output and distributed according to the output distribution map when the atmospheric pressure decreases.
After acceleration, when the accelerator is returned and the vehicle shifts to constant speed driving, the motor output is decreased while the engine output is constant (= boundary output Peb1), and the requested output (requested output) of the vehicle is lower than the boundary output Peb1 of the engine. Then, the motor 11 is switched to the function of the generator, and the battery 14 is charged while ensuring the required output.

In this way, when the atmospheric pressure decreases, such as when traveling at high altitudes, the output distribution of the motor 11 is made larger than normal, and the output of the engine 1 is relatively decreased, thereby shifting from FIG. 12 to FIG. Can be reduced at the same time.
Further, only when the charge amount SOC of the battery 14 is sufficient, the output distribution is performed when the atmospheric pressure is reduced. When the charge amount SOC is insufficient, the normal control is maintained to prevent overdischarge due to the increase in motor output distribution. .

  Further, from the normal time, the boundary output (boundary output at which engine driving is started) Pmb that travels only by the motor 11 is shifted to the low output side, and the engine output is made larger than the vehicle required output to function the motor as a generator. By doing so, the increase in power consumption due to the increase in motor output on the high load side can be supplemented on the low load side, and the battery charge amount is maintained well and the control when the atmospheric pressure drops is performed stably for a long time. be able to.

  In the above embodiment, the boundary output Peb1 of the engine 1 and the boundary output Pmb1 of the motor travel when the atmospheric pressure is reduced are set to constant values. However, as shown in FIGS. 760 mmHg) may be variably set based on the pressure drop amount ΔPex from the battery charge amount SOC. Specifically, the boundary output Peb1 of the engine 1 is set to be smaller as the pressure drop amount ΔPex is larger or as the battery charge amount SOC is larger, so that the output distribution of the motor 11 is larger. Further, the motor traveling boundary output Pmb1 is set to be smaller as the atmospheric pressure decrease amount ΔPex is larger or the battery charge amount SOC is smaller. As a result, power generation is started earlier and the motor power consumption when the atmospheric pressure decreases is reduced. It is possible to secure a sufficient amount of power generation accompanying the increase.

Moreover, although the said embodiment was applied to the vehicle provided with the parallel type | mold hybrid prime mover which can connect the engine 1 and the motor 11 in parallel and can control each rotation speed and torque independently, an engine and a motor are connected in series. It can also be applied to vehicles equipped with connected series-type hybrid prime movers.
FIG. 16 shows a system configuration of an embodiment in which the present invention is applied to a vehicle equipped with such a series type hybrid prime mover.

In the present embodiment, the motor 11 is connected to the output shaft of the engine 1, and is connected to the gear 5 a of the axle 5 via the continuously variable transmission 31, the clutch 32, and the gear 33 connected to the output shaft of the motor 11. ing.
Also in the present embodiment, the engine and motor outputs are set in the same manner as in the first embodiment, but the motor rotational speed Nmi is equal to the engine rotational speed Nei, and the motor torque Tm1 is calculated by the following equation. Is different.

  Tmi = Pmi / Nei; i = 1, 2 (see FIGS. 17 and 18)

The system block diagram of the drive control apparatus of the hybrid vehicle which concerns on the 1st Embodiment of this invention. The control block diagram of embodiment same as the above. The flowchart which shows the main routine of control of embodiment same as the above. The flowchart which similarly shows a subroutine. The characteristic figure of the output distribution map for normal time control similarly. The characteristic figure of the output distribution map for control at the time of atmospheric pressure fall similarly. The engine operating point table. The characteristic view which similarly shows the relationship between the engine speed and torque. The characteristic view which similarly shows the rotational speed and torque relationship of a motor. The figure which similarly shows the motor command value delay characteristic at the time of map switching. The time chart which shows the change of the various state quantities at the time of control by embodiment same as the above. The figure which shows discharge | emission amount of PM and NOx at the time of high-altitude high load. The figure which shows discharge | emission amount of PM and NOx at the time of high altitude low load. The figure which shows the engine boundary output with respect to pressure fall amount and battery charge amount. The figure which shows the boundary output of the motor driving | running | working with respect to pressure fall amount and battery charge amount. The system block diagram of the drive control apparatus of the hybrid vehicle which concerns on the 2nd Embodiment of this invention. The characteristic view which shows the relationship between the rotational speed of an engine and torque in embodiment same as the above. The characteristic view which similarly shows the rotational speed and torque relationship of a motor.

Explanation of symbols

1 engine (internal combustion engine)
2 1st continuously variable transmission 3 1st clutch 4a gear 5 axle 5a gear 6 engine control device 11 motor 12 inverter 13 battery 14 2nd continuously variable transmission 15 2nd clutch 16 motor control device 17 hybrid control device 21 Accelerator opening sensor 22 Vehicle speed sensor 23 Pressure sensor 31 Continuously variable transmission 32 Clutch 33 Gear

Claims (10)

An engine, a motor, driving force calculating means for calculating the driving force of the engine and the motor, power storage means for supplying electric power to the motor, motor control means for controlling the driving of the motor, and the engine. An engine control means for controlling the air-fuel ratio of the air-fuel mixture.
The drive force control device for a hybrid vehicle, wherein the drive force calculation means increases the ratio of the motor drive force when detecting a decrease in atmospheric pressure as compared with a normal case.   2. The driving force control apparatus for a hybrid vehicle according to claim 1, wherein the decrease in the atmospheric pressure is estimated from an intake pressure detection value of the engine and an operating state.   3. The driving force control apparatus for a hybrid vehicle according to claim 1, wherein the decrease in the atmospheric pressure is estimated from a detected mass intake air flow rate of the engine and an operating state.   The hybrid vehicle driving force control device according to claim 1, further comprising a navigation device, wherein the decrease in the atmospheric pressure is determined from altitude information of the navigation device.   The driving force control apparatus for a hybrid vehicle according to any one of claims 1 to 4, wherein the increase in the motor driving force ratio is controlled to be greater as the atmospheric pressure decreases.   6. The driving force control apparatus for a hybrid vehicle according to claim 1, wherein the increase in the motor driving force ratio is controlled to be larger as the charging amount of the power storage unit is larger. .   The driving force control apparatus for a hybrid vehicle according to any one of claims 1 to 6, wherein the motor driving force is not increased when the charge amount of the power storage means is less than a predetermined value.   When a decrease in atmospheric pressure is detected and the engine target output is smaller than the predetermined output, the fuel injection amount is increased to increase the engine output, and the increased amount of the engine output is recovered by generating the motor. The driving force control apparatus for a hybrid vehicle according to any one of claims 1 to 7.   9. The driving force control of a hybrid vehicle according to claim 1, wherein the motor maximum output value during vehicle traveling by motor driving is decreased as the charging amount of the power storage unit is smaller. apparatus.   The hybrid vehicle driving force control device according to any one of claims 1 to 9, wherein when the motor driving force is switched, a delay is added to the motor driving force command value.

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