JP4155378B2 - Drive control device for four-wheel drive vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive control device for a hybrid four-wheel drive vehicle in which either a front shaft or a rear shaft is driven by an engine via a mechanical automatic transmission and the other is driven by a motor.
[0002]
[Prior art]
In recent years, in vehicles such as automobiles, hybrid vehicles using both an engine and a motor have been developed and put into practical use from the viewpoint of low pollution and resource saving, and there are various drive modes for the engine and motor of such a hybrid vehicle. Has been proposed. For example, in Japanese Patent Laid-Open No. 9-284911, one of a front shaft and a rear shaft is driven by an engine via a continuously variable transmission (CVT), and the other is driven by a motor. A four-wheel drive vehicle capable of selecting 4WD is disclosed.
[0003]
In addition to the combination of the torque converter and CVT shown in the prior art, the transmission and the engine connected to the engine automate the clutch and gear shift of the manual transmission with an actuator and maintain a high efficiency while maintaining a high efficiency. Similarly, it is considered to use an automatic mechanical transmission (AMT) that does not require manual shifting.
[0004]
[Problems to be solved by the invention]
By the way, in general, in manual transmissions, gears are shifted by shifting the clutch while returning the throttle of the engine at the time of shifting, so that acceleration is lost at the time of shifting and a shift shock with a strong pulling feeling occurs. In particular, in a mechanical automatic transmission, there is a case where a gear shift is performed even if the driver does not perform a gear shift operation, and there is a tendency that an unpleasant feeling with respect to a gear shift shock tends to be strong, and there is a high need for improvement.
[0005]
The present invention has been made in view of the above circumstances, and in a four-wheel drive vehicle in which either the front shaft or the 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 that suppresses a shift shock accompanied by a strong pull-in feeling that is expected to occur, for example, is natural even if a shift not performed by a driver is performed, and does not cause discomfort to the driver. It is intended to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a drive control device for a four-wheel drive vehicle according to the present invention as set forth in claim 1 drives either the front shaft or the rear shaft by an engine via a mechanical automatic transmission, and the other motor. In the drive control device for a four-wheel drive vehicle driven by the motor, the other driven by the motor is provided with a left / right driving force distribution variable means capable of changing the driving force distribution between the left and right wheels, and before the shift of the mechanical automatic transmission. A change in vehicle behavior that occurs in response to a change in drive control from to the time of shifting, and a change in the drive force distribution between the left and right wheels by the left and right drive force distribution variable means to suppress the vehicle behavior change. during the shifting of the mechanical automatic transmission is characterized in that the total driving force of the four wheels during the gear shift controls the driving force of the motor to maintain the total drive force of the four wheels of the pre-shift.
[0007]
According to a second aspect of the present invention, there is provided a drive control device for a four-wheel drive vehicle according to the first aspect of the present invention. In the drive control device for a four-wheel drive vehicle according to the first aspect, when the road surface friction coefficient of the traveling road surface is low, The upper limit driving force of the wheels driven by the motor is limited during shifting of the automatic transmission.
[0009]
In other words, the drive control device for a four-wheel drive vehicle according to claim 1 is provided with a left and right driving force distribution variable means capable of varying the driving force distribution between the left and right wheels on the other side driven by the motor, and the shift of the mechanical automatic transmission. A change in vehicle behavior that occurs in response to a change in drive control from the front to the front during a shift is estimated, and the drive force distribution between the left and right wheels is varied by the left and right drive force distribution variable means to suppress the vehicle behavior change, and the machine During the shifting of the automatic transmission, the driving force of the motor is controlled so that the total driving force of the four wheels being shifted maintains the total driving force of the four wheels before the shifting. 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 ’s natural, and it does n’t make the driver uncomfortable. In addition, during shifting, the state of traveling on the front and rear shafts changes to the traveling state of only the other shaft driven by the motor, so the understeer tendency or oversteer tendency newly generated in the vehicle is suppressed by the left and right driving force distribution variable means, The vehicle behavior at the time of shifting to the shift can be stabilized.
[0010]
The drive control device for a four-wheel drive vehicle according to claim 2 limits the upper limit driving force of a wheel driven by a motor during a shift of a mechanical automatic transmission when the road surface friction coefficient of a traveling road surface is low. Thus, when the driving force is supplemented by the motor at the time of shifting, the driving force of the other shaft driven by the motor is prevented from becoming too large so that stable vehicle behavior can be maintained even on low μ roads. To do.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described 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 the configuration of a rear final drive device, and FIG. 3 is a drive control program. FIG. 4 is a flowchart of a front wheel driving force calculation routine, FIG. 5 is a characteristic explanatory diagram of engine torque with respect to engine speed and throttle opening, FIG. 6 is a characteristic explanatory diagram of clutch transmission torque capacity with respect to a clutch release stroke, and FIG. It is a time chart explaining the effect by a drive control device.
[0013]
In FIG. 1, the code | symbol 1 shows a vehicle and the code | symbol 2 is an engine and is arrange | positioned at the vehicle front part. The output shaft of the engine 2 is connected to the 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), so that the left front wheel 5fl. And the right front wheel 5fr is driven.
[0014]
The mechanical automatic transmission 3 includes a clutch device configured by a normal mechanical clutch that presses and separates a clutch disc from the flywheel of the engine 2, and a gear-type transmission capable of shifting between a rear stage and a plurality of forward stages. (Not shown). When the transmission is automatically shifted, the clutch device is automatically connected / disconnected, and is capable of automatic shifting as well as manual shifting.
[0015]
The select lever 3a of the vehicle 1 operated by the driver includes an N (neutral) range, an R (reverse) range, a D (drive) range corresponding to the automatic transmission mode, and an M (manual) range corresponding to the manual transmission mode. Is provided.
[0016]
On the other hand, reference numeral 6 denotes a motor, and the output shaft of the motor 6 is connected to the rear final drive device 7, and the motor driving force is transmitted to the rear shaft 8 via the rear final drive device 7 so that the left rear The wheel 5rl and the right rear wheel 5rr are configured to be driven.
[0017]
The motor 6 is driven by the electric power stored in the battery 10 from the engine-driven generator 9. Further, when the vehicle 1 is decelerated, it is configured to generate electric power by the motor 6 and store it in the battery 10, thereby enabling an energy efficient operation.
[0018]
Further, as shown in FIG. 2, the rear final drive device 7 has a differential function between the left and right wheels and a power distribution function, and includes a bevel gear type differential mechanism section 11 and a gear mechanism section comprising three rows of gears. 12 and two sets of clutch mechanisms 13 that vary the distribution of driving force between the left and right wheels in the rear wheel, and are housed integrally in the differential carrier 14.
[0019]
The drive pinion 15 that transmits the driving force from the motor 6 is meshed with a final gear 17 provided on the outer periphery of the differential case 16 of the differential mechanism section 11.
[0020]
The differential mechanism unit 11 is configured by accommodating a differential pinion 19 rotatably supported on a pinion shaft 18 fixed to the differential case 16 and left and right side gears 20L, 20R meshing with the differential pinion 19 in the differential case 16. Yes. The end portions of the rear shaft 8 are respectively attached to the side gears 20L and 20R.
[0021]
The gear mechanism portion 12 includes first, second, and third gears 21z1, 21z2, and 21z3 arranged in parallel from the differential mechanism portion 11 side with the rear shaft 8 as a rotation center, and the first gear 21z1 is The second and third gears 21z2 and 21z3 are fixed to the rear shaft 8 and fixed to the differential case 16.
[0022]
These first, second, and third gears 21z1, 21z2, and 21z3 are meshed with fourth, fifth, and sixth gears 21z4, 21z5, and 21z6 disposed on the same rotation axis, and the fourth gear. The gear 21z4 is configured to be freely connected / released with the fifth gear 21z5 via the first differential control clutch 22a of the clutch mechanism section 13. Further, the fourth gear 21z4 is configured to be connectable and disengageable with the sixth gear 21z6 via the second differential control clutch 22b of the clutch mechanism section 13.
[0023]
The number of teeth z1, z2, z3, z4, z5 and z6 of the first, second, third, fourth, fifth and sixth gears 21z1, 21z2, 21z3, 21z4, 21z5 and 21z6 are For example, it is set to 82, 78, 86, 46, 50, 42, and the second, second, and second gears 21z1, 21z4 are referred to as the reference gear train ((z4 / z1) = 0.56). The gear train of the fifth gears 21z2 and 21z5 ((z5 / z2) = 0.64) is accelerated, and the gear train of the third and sixth gears 21z3 and 21z6 ((z6 / z3) = 0.49). It is a gear train for reduction.
[0024]
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 is equally distributed to the left and right rear wheels 5rl and 5rr via the differential mechanism section 11 as they are. However, when the first differential control clutch 22a is connected and operated, the torque distribution of the right rear wheel 5rr is increased, and the left turnability of the vehicle is improved when the road surface μ is normal. Conversely, when the second differential control clutch 22b is connected and operated, the torque distribution of the left rear wheel 5rl is increased, and the right turning performance of the vehicle is improved if the road surface μ is normal.
[0025]
The first and second differential control clutches 22a and 22b are connected to a differential control clutch drive unit 23 configured by a hydraulic circuit having a plurality of solenoid valves, and the hydraulic pressure generated by the differential control clutch drive unit 23. Is released and connected. A control signal (an output signal for each solenoid valve) for driving the differential control clutch drive unit 23 is output from the control device 30. Thus, the rear final drive device 7 and the differential control clutch drive unit 23 constitute left and right driving force distribution varying means.
[0026]
The control device 30 is constituted by a microcomputer and its peripheral circuits, and is related to overall control of the entire vehicle, that is, control related to the engine 2, control related to the mechanical automatic transmission 3 (mainly control of the clutch device), and motor 6. The control related to the battery 10, the control related to the differential control clutch drive unit 23, and the like are executed, and the drive control of the vehicle 1 is executed.
[0027]
In the control device 30, regarding the drive control, sensor values such as 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, and the like. A switch signal such as a shift position and an estimated calculation value such as a road surface friction coefficient μ are input, and drive control of the vehicle 1 is executed according to a drive control program described later.
[0028]
Hereinafter, the drive control executed by the control device 30 will be described based on the flowchart of the drive control program of FIG. This drive control program is executed every predetermined time. First, in step (hereinafter abbreviated as “S”) 101, necessary parameters, that is, the clutch release stroke of the clutch device of the mechanical automatic transmission 3, the engine speed Ne, the throttle Sensor values such as opening degree Th, gear ratio i, vehicle speed V, steering angle θ, switch signals such as shift position, and estimated calculation values such as road surface friction coefficient μ are input.
[0029]
Next, in S102, normal drive control is executed. This normal drive control is basically based on controlling the rear wheel drive force to a value obtained by multiplying the front wheel drive force by a predetermined ratio, for example, 0.3 in order to exhibit the performance as a four-wheel drive vehicle. Execute. When the performance as a four-wheel drive vehicle is not required due to traveling conditions such as a high μ road, the drive control is performed by varying the ratio of multiplying the front wheel drive force by 0 or the like.
[0030]
Thereafter, the process proceeds to S103, in which it is determined whether or not shifting has been started. This shift start determination is made from the clutch release stroke value. As a result of the determination, if the shift is not started, the process returns to S101 again, and if the shift is started, the process proceeds to S104.
[0031]
In S104, the front wheel driving force Ffa is calculated according to the front wheel driving force Ffa calculation routine shown in FIG. In the flowchart of FIG. 4, first, in S201, the engine torque Te is set with reference to a preset map (FIG. 5) based on the engine speed Ne and the throttle opening degree Th.
[0032]
Next, in S202, the clutch transmission torque capacity Tc is set with reference to a map (FIG. 6) set in advance based on the clutch release stroke.
[0033]
Thereafter, the process proceeds to S203, where the engine torque Te and the clutch transmission torque capacity Tc are compared. If the engine torque Te is smaller than the clutch transmission torque capacity Tc, the process proceeds to S204, and the transmission input torque Ti is set as the engine torque Te. If the engine torque Te is equal to or greater than the clutch transmission torque capacity Tc, the process proceeds to S205, and the transmission input torque Ti is set to the clutch transmission torque capacity Tc.
[0034]
Then, after setting the transmission input torque Ti in S204 or S205, the process proceeds to S206, and the front wheel driving force Ffa is calculated based on the following equation (1).
Ffa = Ti · i / R (1)
Here, R is the tire radius.
[0035]
After calculating the front wheel driving force Ffa in S104, the process proceeds to S105, and the target four-wheel total driving force F4t is calculated.
This target four-wheel total driving force F4t is calculated based on the following equation (2) with 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. As a shift time with T0 as a target,
F4t = (F2-F1) .t / T0 + F1 (2)
That is, a change in the target four-wheel total driving force F4t during the shift according to the elapsed time t is estimated from the total four-wheel driving force F1 before the shift and the four-wheel total drive force F2 after the shift, The target four-wheel total driving force F4t is set smoothly.
[0036]
Here, the four-wheel total driving force F1 before the shift is given by assuming that the engine torque before the shift is Te1, the gear ratio is i1, and the final gear ratio is Gf.
F1 = Te1, i1, Gf / R
The engine torque Te1 is obtained with reference to FIG. 5 based on the engine speed Ne1 and the throttle opening degree Th1 before shifting.
[0037]
Also, the four-wheel total driving force F2 after the shift is calculated by assuming that the engine torque after the shift is Te2 and the gear ratio is i2.
F2 = Te2, i2, Gf / R
Here, the engine torque Te2 after the shift is obtained with reference to FIG. 5 based on the engine speed Ne2 and the throttle opening degree Th2 after the shift. Then, the engine speed Ne2 after the shift is calculated as Ne2 = Ne1 · i1 / i2.
[0038]
Next, in S106, the 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)
[0039]
Next, in S107, it is determined whether or not the rear wheel target driving force Frt exceeds the tire slip limit. The limit value that defines the tire slip limit is set according to the road surface friction coefficient μ, and is set to limit value = Wr · μ · R (Wr is the rear axle load).
[0040]
As a result of S107, if the rear wheel target driving force Frt is equal to or greater than the limit value, the rear wheel target driving force Frt is limited to the limit value (= Wr · μ · R) in S108, 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 proceeds to S109 as it is.
[0041]
In S109, the left / right driving force distribution ratio Fri / Fro (the driving force of the turning inner wheel / the driving force of the turning outer wheel) is set according to the vehicle behavior.
Fri / Fro = k · | θ | · V (4)
Here, k is a constant.
[0042]
That is, the front wheel drive has a weak understeering tendency, and the rear wheel drive has an oversteering turning characteristic. Therefore, since the rear wheels are driven by the motor 6 at the time of shifting, the steering characteristic changes from a weak understeering tendency to an oversteering tendency, which may give an unnatural feeling to the driver. Therefore, the left / right driving force distribution ratio Fri / Fro is corrected and set in order to suppress the change in the steering characteristic. Here, since the change in the turning characteristic becomes more significant as the steering angle θ and the vehicle speed V are larger, the left / right driving force distribution ratio Fri / Fro is, for example, the steering angle θ and the vehicle speed V as shown in the above equation (4). The value is proportional to the product. In this embodiment, since the rear wheels are driven by a motor, the rear wheels are driven at the time of shifting, and the torque of the turning outer wheel is reduced to alleviate the oversteer tendency, but the front wheels are driven by a motor. In such a case, an understeer tendency tends to occur. Therefore, the understeer tendency can be reduced by reducing the torque of the turning inner wheel.
[0043]
In S110, the motor 6 is driven and controlled based on the rear wheel target driving force Frt set by limiting in S106 or S108, and the differential control clutch driving unit based on the left / right driving force distribution ratio Fri / Fro calculated in S109. A control signal is output to 23 and the differential control clutch is controlled.
[0044]
Thereafter, it is determined in S111 whether or not the shift has been completed. If the shift has not been completed, the processing from S104 is repeated again, and if the shift has been completed, the routine is exited.
[0045]
The effects of the drive control apparatus 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 shown in FIG. As shown in a), it is represented by the sum of the driving force of the front wheels and the driving force of the rear wheels.
[0046]
Thereafter, as shown in FIG. 7 (b), when the clutch device of the mechanical automatic transmission 3 starts shifting toward the release from the value of the clutch release stroke, it is driven by the engine 2 as shown in FIG. 7 (a). The driving force of the front wheels is reduced, and the driving force of the front wheels becomes zero during 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 wheels is the value obtained by the above equation (3). Thus, the output is smoothly compensated so as to obtain the total driving force of the four wheels. For this reason, a shift shock accompanied by a strong pull-in feeling that is expected to occur due to a shift is suppressed, and even if a shift that does not depend on a driver operation is performed, it is natural to prevent the driver from feeling uncomfortable. Also, when supplementing with motor driving force during shifting, the driving force of the rear wheel is limited to a limit value (= Wr · μ · R) corresponding to the road surface friction coefficient μ, so that the rear wheel is sure to slip. To be prevented.
[0047]
Further, the driving force of the rear wheels at this time is largely distributed to the turning outer rear wheel 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 making a turn, the steer characteristic of the vehicle does not change, and a stable turn can be continued.
[0048]
Then, as shown in FIG. 7 (b), when the clutch device of the mechanical automatic transmission 3 is engaged from the value of the clutch release stroke, the engine 2 is driven as shown in FIG. 7 (a). The driving force of the front wheels is increased again, and the driving force of the rear wheels driven by the motor 6 is decreased again. Thereafter, when the clutch device of the mechanical automatic transmission 3 is engaged, normal drive control is resumed.
[0049]
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 also be applied to a mechanical automatic transmission with a sub-clutch. Since torque can be transmitted, the rear wheel target driving force Frt can be suppressed low, and the current consumption of the battery 10 can be suppressed.
[0050]
Further, in the present embodiment, the left and right driving force distribution function provided in the rear final drive device 7 is used to distribute the driving force to the left and right, but the wheel motor is used to distribute the driving force of the left and right wheels. Even if it performs, the same effect can be acquired.
[0051]
【The invention's effect】
As described above, according to the present invention, 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. Therefore, it is possible to suppress a shift shock accompanied by a strong pull-in feeling that is expected to occur. For example, even if a shift not performed by the driver is performed, it is natural to effectively prevent 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 a configuration explanatory diagram of a rear final drive device. FIG. 3 is a drive control program flowchart. FIG. 4 is a front wheel drive force calculation routine flowchart. [Description of characteristics of engine torque with respect to engine speed and throttle opening] [FIG. 6] Description of characteristics of clutch transmission torque capacity with respect to clutch release stroke [FIG. 7] Time chart illustrating effects of drive control device [Description 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 (right and left driving force distribution variable means)
30 Control device

Claims (2)

In a drive control device for a four-wheel drive vehicle in which either the front shaft or the rear shaft is driven by an engine via a mechanical automatic transmission and the other is driven by a motor.
The other driven by the motor is provided with a left / right driving force distribution variable means capable of changing the driving force distribution between the left and right wheels,
A change in vehicle behavior that occurs in response to a change in drive control from before the gear shift to during the gear shift of the mechanical automatic transmission is estimated, and the drive force distribution between the left and right wheels is varied by the left and right drive force distribution varying means. To suppress the above vehicle behavior change,
During the shift of the mechanical automatic transmission, the four-wheel drive is characterized in that the driving force of the motor is controlled so that the total driving force of the four wheels being shifted maintains the total driving force of the four wheels before the shifting. Car drive control device.   2. The four-wheel drive vehicle according to claim 1, wherein when the road surface friction coefficient of the traveling road surface is low, an upper limit driving force of a wheel driven by the motor is limited during a shift of the mechanical automatic transmission. Drive control device.

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