JP2001347846A - Driving control device for four-wheele drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a speed changing shock with a strong sense of pulling-in feeling expected to be generated by speed changing and to prevent giving a sense of discomfort to a driver naturally even when speed changing not by a driver's operation is carried out on a four-wheeled vehicle wither of a front axle and a rear axle of which is driven by an engine through a mechanical automatic transmission and the other of which is driven by a motor. SOLUTION: The engine 2 drives front wheels 5fl, 5fr through the mechanical automatic transmission 3, and the motor 6 drives rear wheels 5rl, 5rr through a rear final drive device 7 free to distribute left and right driving force. A control device 30 assumes a change of target four-wheel total driving force in the middle of speed changing in accordance with speed changing passing time from four-wheel total driving force before speed changing and four-wheel total driving force after speed changing when speed changing of the mechanical automatic transmission 3 is started and outputs the target four-wheel total driving force in the middle of speed changing by setting it and supplementing it by the motor 6. At this time, the driving force is limited in accordance with a road surface friction coefficient, and left and right driving force distribution is varied in accordance with car velocity and a revolving state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control for a hybrid four-wheel drive vehicle in which one of a front shaft and a rear shaft is driven by an engine via a mechanical automatic transmission and the other is driven by a motor. Related to the device.

[0002]

2. Description of the Related Art In recent years, for vehicles such as automobiles, hybrid vehicles using both engines and motors have been developed and put into practical use from the viewpoint of low pollution and resource saving. Various driving modes have been proposed. For example, Japanese Patent Application Laid-Open No. 9-28491
No. 1 discloses that one of a front shaft and a rear shaft is continuously variable transmission (C
A four-wheel drive vehicle is disclosed that is driven by an engine via VT) and the other is driven by a motor to select FF, RR, or 4WD depending on the running state.

[0003] In addition to a combination of a torque converter and a CVT shown in the prior art, a clutch and a gear shift of a manual transmission are automated by an actuator as a transmission connected to the engine. Similar to automatic transmissions, mechanical automatic transmissions that do not require manual shifting (AMT: Automatic Mechanical Transmission)
It is considered to use.

[0004]

In general, in a manual transmission, the clutch is disengaged while returning the throttle of the engine at the time of shifting, so that the speed is changed. Occurs. In particular, in a mechanical automatic transmission, a shift may be performed without a driver performing a shift operation.
There is a tendency for discomfort to shift shocks to increase, and there is a high need for improvement.

The present invention has been made in view of the above circumstances, and relates to a four-wheel drive vehicle in which one of a front shaft and a rear shaft is driven by an engine via a mechanical automatic transmission and the other is driven by a motor. The present invention suppresses a shift shock accompanied by a strong pulling feeling that is expected to occur due to a shift, and drives a four-wheel-drive vehicle that does not cause discomfort to the driver even if the shift is not performed by the driver. It is intended to provide a control device.

[0006]

According to a first aspect of the present invention, there is provided a drive control apparatus for a four-wheel drive vehicle, wherein one of a front shaft and a rear shaft is controlled via a mechanical automatic transmission. In a drive control device for a four-wheel drive vehicle that is driven by an engine and the other is driven by a motor, during shifting of the mechanical automatic transmission, the total driving force of the four wheels during shifting is the sum of the four wheels before shifting. The driving force of the motor is controlled to maintain the driving force.

According to a second aspect of the present invention, there is provided a drive control apparatus for a four-wheel drive vehicle according to the first aspect of the present invention, wherein the road surface friction coefficient of a running road surface is low. An upper limit driving force of wheels driven by the motor is limited during shifting of the mechanical automatic transmission.

Further, a drive control device for a four-wheel drive vehicle according to the present invention according to claim 3 is a drive control device according to claim 1 or 2.
In the drive control device for a wheel-drive vehicle, the other side driven by the motor is provided with a left-right drive force distribution variable means capable of variably changing the drive force distribution between the left and right wheels, from before the shift of the mechanical automatic transmission to during the shift. And estimating a change in vehicle behavior that occurs in accordance with a change in drive control of the vehicle, and varying the driving force distribution between the left and right wheels by the left and right driving force distribution varying means to suppress the vehicle behavior change. .

That is, in the drive control device for a four-wheel drive vehicle according to the first aspect, the total driving force of the four wheels during shifting is reduced by the total driving force of the four wheels before shifting during shifting of the mechanical automatic transmission. Control the driving force of the motor to maintain it. For this reason, even when shifting from the normal running state to the shift state, the interrupted driving force from the engine is supplemented by the motor, and the shift shock accompanied by a strong pull-in feeling is suppressed. It is natural and does not cause any discomfort to the driver.

Further, the drive control apparatus for a four-wheel drive vehicle according to the present invention, when the road surface friction coefficient of the running road surface is low,
By limiting the upper limit driving force of the wheels driven by the motor during shifting of the mechanical automatic transmission, the driving force of the other shaft driven by the motor increases when the driving force is complemented by the motor during shifting. It is possible to prevent the vehicle from being too long and to maintain stable vehicle behavior even on a low μ road.

Further, in the drive control device for a four-wheel drive vehicle according to a third aspect of the present invention, there is provided a left-right driving force distribution variable means capable of changing the driving force distribution between the right and left wheels on the other side driven by the motor, Estimates changes in vehicle behavior that occur in response to changes in drive control before and during gear shifting of the machine, and suppresses changes in vehicle behavior by varying the drive power distribution between the left and right wheels using left and right drive force distribution variable means. . In other words, the vehicle shifts from a state in which the vehicle travels on the front and rear axes to a state in which only the other axis is driven by the motor during gear shifting. Stabilize behavior.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show an embodiment of the present invention, FIG. 1 is an overall explanatory diagram of a drive control device mounted on a vehicle, FIG. 2 is an explanatory diagram of a configuration of a rear final drive device, and FIG. Flow chart, FIG.
FIG. 5 is a flowchart of a front wheel driving force calculation routine, FIG. 5 is a diagram illustrating characteristics of engine torque with respect to engine speed and throttle opening, FIG. 6 is a diagram illustrating characteristics of clutch transmission torque capacity with respect to clutch release stroke, and FIG. It is a time chart explaining an effect.

In FIG. 1, reference numeral 1 denotes a vehicle, and reference numeral 2 denotes an engine, which is arranged at the front of the vehicle. The output shaft of the engine 2 is connected to a mechanical automatic transmission 3, and the engine driving force is transmitted from the mechanical automatic transmission 3 to the front shaft 4 via a differential device (not shown), and the left front wheel 5 fl And the right front wheel 5fr is driven.

The mechanical automatic transmission 3 includes a clutch device including a normal mechanical clutch that presses and separates a clutch disk with respect to a flywheel of the engine 2, and a gear-type transmission capable of performing a plurality of rear and forward gears. (Not shown). When the transmission is automatically shifted, the clutch device is automatically connected / disengaged with the automatic transmission, so that not only manual shifting but also automatic shifting can be performed.

The select lever 3a of the vehicle 1 operated by the driver has an N (neutral) range, an R (reverse) range, a D (drive) range corresponding to an automatic shift mode, and an M (equivalent to a manual shift mode). Manual) range is provided.

On the other hand, reference numeral 6 denotes a motor. The output shaft of the motor 6 is connected to a rear final drive device 7, and the driving force of the motor is transmitted to the rear shaft 8 via the rear final drive device 7. , And is configured to drive the left rear wheel 5rl and the right rear wheel 5rr.

The motor 6 is driven by electric power stored in a battery 10 from a generator 9 driven by an engine. Also,
When the vehicle 1 decelerates, the motor 6 generates power and the battery 1
It is configured to store power to 0, and energy-efficient operation is possible.

The rear final drive device 7
As shown in FIG. 2, it has a differential function between the left and right wheels and a power distribution function.
The differential carrier 14 mainly includes a gear mechanism section 12 composed of a row gear and two sets of clutch mechanism sections 13 that vary the distribution of driving force between the left and right wheels in the rear wheels.
It is housed integrally inside.

A drive pinion 15 for transmitting the driving force from the motor 6 is provided on a final gear 1 provided on the outer periphery of a differential case 16 of the differential mechanism 11.
7 is engaged.

The differential mechanism section 11 accommodates a differential pinion 19 rotatably supported by a pinion shaft 18 fixed to a differential case 16 and left and right side gears 20L, 20R meshed with the differential pinion 19 in the differential case 16. It is configured. The end portions of the rear shaft 8 are journaled to the side gears 20L and 20R, respectively.

The gear mechanism 12 includes first, second, and third gears 21z1, 21z2, and 21z3 arranged in order from the differential mechanism 11 with the rear shaft 8 as the center of rotation. The gear 21z1 is fixed to the differential case 16,
The second and third gears 21z2, 21z3 are fixed to the rear shaft 8.

The first, second, and third gears 21z1, 2
1z2 and 21z3 are meshed with fourth, fifth and sixth gears 21z4, 21z5 and 21z6 disposed on the same rotation axis, and the fourth gear 21z4 is connected to the first differential of the clutch mechanism unit 13. It is configured to be freely connected to and disengageable from the fifth gear 21z5 via the control clutch 22a. Also, the fourth gear 2
1z4 is configured to be freely connected to and disengageable from the sixth gear 21z6 via the second differential control clutch 22b of the clutch mechanism 13.

The first, second, third, fourth, fifth and fifth
The sixth gears 21z1, 21z2, 21z3, 21z4, 21z5,
Number of teeth z1, z2, z3, z4, z of 21z6
5, z6 are, for example, 82, 78, 86, 46, 50,
42, and the first and fourth gears 21z1, 21z
Based on the gear train of z4 ((z4 / z1) = 0.56), the gear train of the second and fifth gears 21z2 and 21z5 ((z5
/Z2)=0.64) increases speed, and the third and sixth gears 21z
A gear train of 3,21z6 ((z6 / z3) = 0.49) is a reduction gear train.

Therefore, when both the first and second differential control clutches 22a and 22b are not connected and operated, the driving force from the drive pinion 15 passes through the differential mechanism 11 to the left and right rear wheels 5rl and 5rr. Evenly distributed, when the first differential control clutch 22a is connected and operated, the torque distribution to the right rear wheel 5rr increases,
If it is a normal road surface μ, the left turning property of the vehicle is improved. Conversely, when the second differential control clutch 22b is engaged, the torque distribution of the left rear wheel 5rl is increased, and the right turning property of the vehicle is improved if the road surface is normal μ.

First and second differential control clutch 2
Reference numerals 2a and 22b are connected to a differential control clutch drive unit 23 constituted by a hydraulic circuit having a plurality of solenoid valves, and are released and connected by the hydraulic pressure generated by the differential control clutch drive unit 23. The control signal (output signal for each solenoid valve) for driving the differential control clutch drive unit 23 is
The data is output from the control device 30. In this manner, the rear final drive device 7 and the differential control clutch drive unit 23 constitute a left / right driving force distribution variable unit.

The control device 30 is composed of a microcomputer and its peripheral circuits, and performs comprehensive control of the entire vehicle, that is, control of the engine 2, control of the mechanical automatic transmission 3 (mainly control of the clutch device), The control of the motor 6, the control of the battery 10, the control of the differential control clutch drive unit 23, and the like, and the drive control of the vehicle 1 are executed.

In the control device 30, regarding the drive control, the clutch release stroke of the clutch device of the mechanical automatic transmission 3, the engine speed Ne, the throttle opening Th, the gear ratio i, the vehicle speed V, the steering angle θ, etc. Sensor value,
Switch signals such as shift position and road friction coefficient μ
And the like, and drive control of the vehicle 1 is executed in accordance with a drive control program described later.

Hereinafter, the drive control executed by the control device 30 will be described with reference to the flowchart of the drive control program shown in FIG. This drive control program is executed at predetermined time intervals. First, in step (hereinafter abbreviated as "S") 101, necessary parameters, that is, a clutch release stroke of a clutch device of the mechanical automatic transmission 3, an engine speed Ne, a throttle Sensor values such as the opening degree Th, gear ratio i, vehicle speed V, and steering angle θ, switch signals such as shift position, and estimated calculated values such as road surface friction coefficient μ are input.

Next, the routine proceeds to S102, where normal drive control is executed. This normal drive control means that the rear wheel drive force is
In order to exhibit the performance as a four-wheel drive vehicle, the control is basically performed by controlling the front wheel drive force to a value multiplied by a predetermined ratio, for example, 0.3. If the performance as a four-wheel drive vehicle is not required due to running conditions such as a high μ road or the like, the drive control is performed by changing the ratio of the multiplication by the front wheel drive force to zero or the like.

Thereafter, the program proceeds to S103, in which it is determined whether or not a shift has been started. The start of the shift is determined from the value of the clutch release stroke. As a result of this judgment,
If the shift is not to be started, the process returns to S101. If the shift is started, the process proceeds to S104.

In S104, the front wheel driving force Ffa shown in FIG.
The front wheel driving force Ffa is calculated according to a calculation routine. In the flowchart of FIG. 4, first, in S201, the engine torque Te is set based on the engine speed Ne and the throttle opening Th with reference to a preset map (FIG. 5).

Next, the program proceeds to S202, in which a map previously set based on the clutch release stroke (FIG. 6)
, The clutch transmission torque capacity Tc is set.

Thereafter, the program proceeds to S203, where the engine torque Te is compared with the clutch transmission torque capacity Tc. If the engine torque Te is smaller than the clutch transmission torque capacity Tc, the procedure proceeds to S204, and the transmission input torque Ti is reduced to the engine torque Te. And If the engine torque Te is equal to or greater than the clutch transmission torque capacity Tc, the process proceeds to S205, where the transmission input torque Ti is set to the clutch transmission torque capacity Tc.

After setting the transmission input torque Ti in S204 or S205, the process proceeds to S206, where the front wheel driving force Ffa is calculated based on the following equation (1). Ffa = Ti · i / R (1) where R is a tire radius.

After calculating the front wheel driving force Ffa in S104,
Proceeding to S105, the target four-wheel total driving force F4t is calculated.
The target four-wheel total driving force F4t is calculated based on the following equation (2) using the four-wheel total driving force F1 before shifting, the four-wheel total driving force F2 after shifting, and the elapsed time t from the start of shifting. T0
F4t = (F2−F1) · t / T0 + F1 (2) That is, the elapsed time t is calculated from the total driving force F1 of the four wheels before shifting and the total driving force F2 of the four wheels after shifting. A corresponding change in the target four-wheel total driving force F4t during shifting is estimated, and the target four-wheel total driving force F4t during shifting is set smoothly.

Here, the total driving force F1 of the four wheels before shifting is:
Assuming that the engine torque before shifting is Te1, the gear ratio is i1, and the final gear ratio is Gf, F1 = Te1 · i1 · Gf / R The engine torque Te1 is the engine speed N before shifting.
It is obtained with reference to FIG. 5 based on e1 and the throttle opening Th1.

The total driving force F2 of the four wheels after shifting is given by: F2 = Te2 · i2 · Gf / R where Te2 is the engine torque after shifting and i2 is the gear ratio. Here, the engine torque Te2 after shifting is: This is determined based on the engine speed Ne2 and the throttle opening Th2 after the shift, with reference to FIG. Then, the engine speed Ne2 after the shift is calculated by Ne2 = Ne1 · i1 / i2.

Next, in S106, a rear wheel target driving force Frt is calculated based on the front wheel driving force Ffa calculated in S104 and the target four wheel total driving force F4t calculated in S105. Frt = F4t-Ffa (3)

Next, the routine proceeds to S107, where the rear wheel target driving force F
It is determined whether or not rt exceeds the tire slip limit.
The limit value that defines the slip limit of the tire is set according to the road surface friction coefficient μ, and the limit value = Wr · μ · R (Wr
Is set on the rear shaft load).

As a result of S107, the rear wheel target driving force F
If rt is equal to or larger than the limit value, the target rear wheel drive force Frt is determined in S108.
Is limited to the limit value (= Wr · μ · R), and the process proceeds to S109. On the other hand, as a result of S107, if the rear wheel target driving force Frt does not exceed the limit value, the process directly proceeds to S109.

In step S109, a right / left driving force distribution ratio Fri / Fro (driving force of inner wheels turning / driving force of outer wheels turning) is set according to the vehicle behavior. Fri / Fro = k · | θ | · V (4) where k is a constant.

That is, the front wheel drive has a turning characteristic of a weak understeer tendency, and the rear wheel drive has a turning characteristic of an oversteer tendency. Therefore, during gear shifting, the rear wheels are driven by the motor 6, so that the steering characteristic changes from a weak understeer tendency to an oversteer tendency, which may give the driver an unnatural feeling. Therefore, the right and left driving force distribution ratio Fri / Fro is corrected and set to suppress the change in the steering characteristic. Here, since the change in the turning characteristic becomes more remarkable as the steering angle θ and the vehicle speed V become larger, the left-right driving force distribution ratio F
ri / Fro is, for example, a value proportional to the product of the steering angle θ and the vehicle speed V, as shown in the above equation (4). In the present embodiment, the rear wheels are driven by a motor, so that the rear wheels are driven during gear shifting, and the torque of the turning outer wheels is reduced to reduce the tendency of oversteering. In that case, it tends to understeer,
By reducing the torque of the inside wheel, the tendency to understeer can be reduced.

Then, the process proceeds to S110, in which the motor 6 is driven and controlled based on the rear wheel target driving force Frt set in a limited manner in S106 or S108, and the differential control is performed based on the left / right driving force distribution ratio Fr / Fro calculated in S109. A control signal is output to the clutch drive unit 23 to perform differential control clutch control.

Thereafter, in S111, it is determined whether or not the shift has been completed. If the shift has not been completed, the processing from S104 is repeated again. If the shift has been completed, the routine exits.

The effect of the drive control device according to the embodiment of the present invention will be described with reference to a time chart shown in FIG. First, when the clutch device of the mechanical automatic transmission 3 is in the engaged state from the value of the clutch release stroke in FIG. 7B, normal drive control is performed, and the total driving force of the four wheels is calculated as shown in FIG. As shown in a), it is represented by the sum of the driving force of the front wheel and the driving force of the rear wheel.

Thereafter, as shown in FIG. 7 (b), when the clutch device of the mechanical automatic transmission 3 starts disengagement from the value of the clutch release stroke toward disengagement, FIG.
As shown in (a), the driving force of the front wheels driven by the engine 2 decreases, and the driving force of the front wheels becomes zero during gear shifting. At this time, the driving force of the rear wheels driven by the motor 6 (outer rear wheel + inner rear wheel) gradually increases, and during turning,
The driving force of the rear wheel becomes the value obtained by the above equation (3), and is smoothly supplemented and outputted so as to be the driving force of the four wheels in total. For this reason, a shift shock accompanied by a strong pulling feeling that is expected to occur due to the shift is suppressed, for example,
Even if the shift is not performed by the driver's operation, it is natural, and it is possible to prevent the driver from feeling uncomfortable. In addition, since the driving force of the rear wheel is limited to a limit value (= Wr · μ · R) according to the road friction coefficient μ when supplementing with the motor driving force during gear shifting, it is ensured that the rear wheel slips. Is prevented.

The driving force of the rear wheels at this time is largely distributed to the turning outer rear wheels based on the above equation (4) in consideration of the vehicle speed V of the vehicle 1 and the turning state. For this reason, even if the vehicle 1 is turning, stable turning traveling can be continued without changing the steering characteristics of the vehicle.

As shown in FIG. 7B, when the clutch device of the mechanical automatic transmission 3 is engaged from the value of the clutch release stroke, as shown in FIG. , The driving force of the front wheels driven by the motor 6 is increased again, and the driving force of the rear wheels driven by the motor 6 is reduced again. Thereafter, when the clutch device of the mechanical automatic transmission 3 is engaged, the process returns to the normal drive control again.

Although the mechanical automatic transmission 3 according to the present embodiment has been described as a gear transmission capable of automatic transmission, the present invention can be applied to a mechanical automatic transmission with a sub clutch.
In this case, torque can be transmitted even during gear shifting,
The rear wheel target driving force Frt can be kept low, and the current consumption of the battery 10 can be kept low.

In this embodiment, the driving force is distributed to the left and right by using the left and right power distribution function provided in the rear final drive device 7. The same effect can be obtained even if the driving force is distributed.

[0051]

As described above, according to the present invention,
In a four-wheel drive vehicle in which one of the front shaft and the rear shaft is driven by an engine via a mechanical automatic transmission and the other is driven by a motor, a shift shock with a strong pull-in feeling that is expected to occur due to shifting is produced. Suppressing, for example, even if a shift not performed by the driver's operation is performed, it is natural and effectively prevents the driver from feeling uncomfortable.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of a drive control device mounted on a vehicle.

FIG. 2 is an explanatory diagram of a configuration of a rear final drive device.

FIG. 3 is a flowchart of a drive control program.

FIG. 4 is a flowchart of a front wheel driving force calculation routine.

FIG. 5 is an explanatory diagram of characteristics of an engine torque with respect to an engine speed and a throttle opening.

FIG. 6 is an explanatory diagram of characteristics of a clutch transmission torque capacity with respect to a clutch release stroke.

FIG. 7 is a time chart illustrating the effect of the drive control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 3 Mechanical automatic transmission 4 Front shaft 5fl, 5fr Front wheel 5rl, 5rr Rear wheel 6 Motor 7 Rear final drive device (right and left driving force distribution variable means) 8 Rear shaft 10 Battery 23 Differential control clutch drive unit (Left and right) Driving force distribution variable means) 30 control device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60K 41/00 ZHV B60K 41/00 ZHV 301 301A 301B 301D 301E 41/08 41/08 41/12 41/12 41/28 41/28 B60L 11/14 B60L 11/14 F02D 29/02 F02D 29/02 D // B60K 6/02 B60K 9/00 EF term (reference) 3D039 AA01 AA02 AA05 AB27 AC03 AC13 AC23 AC33 AD02 AD23 3D041 AA53 AB01 AC01 AC17 AC19 AC30 AD02 AD04 AD20 AD31 AD47 AD51 AE03 AE17 AF01 3D043 AA01 AB17 EA02 EA05 EA11 EA42 EA45 EB07 EE01 EE02 EE03 DBEE06 EE12 EF09 EF13 EF21 EB03 A03 DB03 A03 DBA03 EC02 FA04 FB01 5H115 PA01 PG04 PI16 PU01 PU25 QE08 QE10 RB10 RE03 TO04

Claims (3)

[Claims] 1. A drive control device for a four-wheel drive vehicle in which one of a front shaft and a rear shaft is driven by an engine via a mechanical automatic transmission and the other is driven by a motor. A drive control device for a four-wheel drive vehicle, characterized in that during the shifting, the driving force of the motor is controlled so that the total driving force of the four wheels during the shifting operation maintains the total driving force of the four wheels before the shifting. 2. An upper limit driving force of wheels driven by the motor during a shift of the mechanical automatic transmission when a road surface friction coefficient of a running road surface is low. A drive control device for a four-wheel drive vehicle. 3. A driving force distribution variable means for varying the driving force distribution between the left and right wheels provided on the other side driven by the motor, for controlling the driving of the mechanical automatic transmission from before shifting to during shifting. The vehicle behavior change generated by the change is estimated, and the vehicle behavior change is suppressed by varying the drive force distribution between the left and right wheels by the left and right drive force distribution varying means. The drive control device for a four-wheel drive vehicle according to claim 2.