JP2021123257A - Driving force distribution control system of vehicle - Google Patents

Abstract

To provide a driving force distribution control system of a vehicle which can suppress the slip of rear wheels on which the ground load is reduced in towing and accelerating in a four-wheel drive vehicle.SOLUTION: A driving force distribution control system of a vehicle comprises: a driving force distribution device which distributes the driving force of front and rear wheels; and a driving force distribution control device which controls the driving force distribution amount of the front and rear wheels. The driving force distribution control device comprises: towing determination means which determines whether or not a four-wheel drive vehicle is towing a towing object vehicle; and request acceleration detection means which detects the request acceleration of a driver. The driving force distribution control device is configured to control the driving force distribution device such that the driving force distribution amount to the rear wheels of the four-wheel drive vehicle becomes smaller as the request acceleration of the driver is greater when it is determined that the four-wheel drive vehicle is towing the towing object vehicle and the request acceleration of the driver is detected.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle driving force distribution control system, and more particularly to a vehicle driving force distribution control system that controls the driving force distribution amount of the front and rear wheels of a four-wheel drive vehicle capable of towing a towed vehicle.

Conventionally, the torque transmission distribution amount to the auxiliary drive wheels is controlled by controlling the operation of the main drive wheels, which constantly transmit the torque of the drive source, and the torque coupling, which can change the drive force distribution according to the vehicle running condition. A four-wheel drive vehicle to be controlled is known (for example, Patent Document 1).

Patent Document 1 discloses a technique in which a traction determination of a vehicle is performed based on a driving force and an acceleration, and a transmission torque to the auxiliary drive wheels is reduced during traction traveling.

Japanese Unexamined Patent Publication No. 2008-149794

Here, in general, in a four-wheel drive vehicle in which the driving force distribution between the main drive wheels and the sub drive wheels can be controlled, the ground contact load state of the front and rear wheels is estimated in each driving scene including when traveling on a low μ road surface. However, the driving force is distributed so that the tires of the wheels do not slip.

However, the present inventors transmit a force from the towed vehicle that causes the rear part of the towed vehicle to rise as the acceleration increases during towing traveling in which the towing vehicle (four-wheel drive vehicle) pulls the towed vehicle. As a result, we have found that the ground contact load of the rear wheels is reduced, causing the rear wheels to slip. That is, at the time of acceleration, an inertial force acting on the center of gravity of the towed vehicle generates a force in the pitching direction that causes the towed vehicle to lean backward, and such a force causes the rear part of the towed vehicle to move in the vertical direction of the vehicle. It is transmitted as a force to lift it upward, which reduces the ground contact load of the rear wheels.

Therefore, the present invention has been made to solve the above-mentioned problems, and in a four-wheel drive vehicle, driving a vehicle capable of suppressing slippage of the rear wheels, which reduces the ground contact load during traction and acceleration. The purpose is to provide a force distribution control system.

In order to achieve the above object, the present invention is a vehicle driving force distribution control system that controls the distribution amount of the driving force of the front and rear wheels in a four-wheel drive vehicle capable of towing a towed vehicle, and is a four-wheel drive. It is equipped with a driving force distribution device that distributes the driving force of the front and rear wheels of the vehicle and a driving force distribution control device that controls the driving force distribution amount of the front and rear wheels by the driving force distribution device. The driving force distribution control device includes a traction determination means for determining whether or not the driven vehicle is towing the towed vehicle and a required acceleration detecting means for detecting the required acceleration of the driver in the four-wheel drive vehicle. When it is determined by the determination means that the four-wheel drive vehicle is towing the towed vehicle and the required acceleration of the driver is detected by the required acceleration detection means, the larger the required acceleration of the driver, the more the four-wheel drive vehicle It is characterized in that it is configured to control the driving force distribution device so that the amount of driving force distributed to the rear wheels is small.

According to the present invention configured as described above, the driving force distribution control device determines that the four-wheel drive vehicle is towing the towed vehicle, and when the required acceleration of the driver is detected, the driver The driving force distribution device is controlled so that the larger the required acceleration of the four-wheel drive vehicle, the smaller the amount of driving force distributed to the rear wheels of the four-wheel drive vehicle. As a result, when accelerating, the towed vehicle is tilted backward in side view due to inertial force, and even if the ground contact load of the rear wheels of the towing vehicle (four-wheel drive vehicle) decreases, the vehicle moves from the rear wheels to the road surface. The transmitted drive torque can be reduced to suppress the slip of the rear wheels. Therefore, according to the present invention, in a four-wheel drive vehicle, it is possible to suppress the slip of the rear wheels at which the ground contact load decreases during traction and acceleration.

Further, in the present invention, preferably, in the driving force distribution control device, it is determined by the traction determination means that the four-wheel drive vehicle is not towing the towed vehicle, and / or the required acceleration of the driver is determined by the required acceleration detecting means. When is not detected, the four-wheel drive vehicle is towing the towed vehicle by the basic drive force distribution ratio determining means for determining the basic drive force distribution ratio of the front and rear wheels of the four-wheel drive vehicle and the traction determination means. When the determination is made and the required acceleration of the driver is detected by the required acceleration detecting means, the driving force is distributed to the rear wheels with respect to the basic driving force distribution ratio of the front and rear wheels determined by the basic driving force distribution ratio determining means. It has a driving force distribution ratio correcting means for correcting the basic driving force distribution ratio so that the ratio becomes small, and the driving force distribution control device states that the four-wheel drive vehicle is pulling the towed vehicle by the traction determination means. When the determination is made and the required acceleration of the driver is detected by the required acceleration detecting means, the driving force distribution amount to the rear wheels is calculated based on the driving force distribution ratio corrected by the driving force distribution ratio correction means. It is configured to control the driving force distribution device.
According to the present invention configured as described above, the driving force distribution control device suppresses slip depending on the basic driving force distribution ratio (for example, road surface μ) of the front and rear wheels during non-traction and / or non-acceleration. (Distribution ratio that reduces heat generation and energy loss when the driving force distribution device is a coupling device with multiple friction plates, etc.) is determined, and the basic drive is used during traction and acceleration. Since the force distribution ratio is corrected, the driving force distribution amount to the rear wheels is calculated based on the corrected driving force distribution ratio, and the driving force distribution device is controlled, slipping of the rear wheels is suppressed more effectively. can do.

Further, in the present invention, preferably, the four-wheel drive vehicle is a four-wheel drive vehicle in which the front wheels are the main driving wheels and the driving force of the front wheels is distributed to the rear wheels by a driving force distribution device. The force distribution control device is configured to control the driving force distribution device so that the larger the required acceleration of the driver, the smaller the amount of driving force distributed to the rear wheels of the four-wheel drive vehicle.
According to the present invention configured in this way, in a four-wheel drive vehicle, the front wheels are the main driving wheels, and the driving force of the front wheels is distributed to the rear wheels by a driving force distribution device, so-called FF (front). It is a four-wheel drive vehicle based on engine front drive), and the larger the driver's required acceleration, the smaller the amount of driving force distributed to the rear wheels of the four-wheel drive vehicle, so it effectively suppresses the slip of the rear wheels. be able to.

Further, in the present invention, preferably, the four-wheel drive vehicle is a four-wheel drive vehicle in which the rear wheels are the main driving wheels and the driving force of the rear wheels is distributed to the front wheels by the driving force distribution device. The force distribution control device is configured to control the driving force distribution device so that the larger the required acceleration of the driver, the larger the amount of driving force distributed to the front wheels of the four-wheel drive vehicle.
According to the present invention configured in this way, in a four-wheel drive vehicle, the rear wheels are the main driving wheels, and the driving force of the rear wheels is distributed to the front wheels by a driving force distribution device, so-called FR (front). It is a four-wheel drive vehicle based on (engine rear drive), and the larger the driver's required acceleration, the larger the amount of driving force distributed to the front wheels of the four-wheel drive vehicle. By the amount, the amount of driving force distributed to the rear wheels can be reduced, which effectively suppresses the slip of the rear wheels.

Further, in the present invention, preferably, the towing determination means of the driving force distribution control device determines that the four-wheel drive vehicle is towing the towed vehicle when the towing travel mode is selected by the driver.
According to the present invention configured as described above, when the driver selects the towing travel mode, the driving force distribution control at the time of towing is performed, so that the driver's discomfort can be suppressed.

Further, in the present invention, preferably, a towed vehicle connection determination device for determining whether or not the non-towed vehicle is connected to a connecting portion provided at the rear of the four-wheel drive vehicle is provided, and the driving force is distributed. The towing determination means of the control device accepts the driver's selection of the towing driving mode while the towed vehicle connection determination device determines that the towed vehicle is connected, and the four-wheel drive vehicle tows the towed vehicle. Judge that it is.
According to the present invention configured in this way, the towed vehicle is towed while the towed vehicle is connected to the connecting portion of the four-wheel drive vehicle, that is, while the towed vehicle is actually towed. Therefore, it is possible to more effectively execute the driving force distribution control at the time of towing.

According to the vehicle driving force distribution control system according to the present invention, in a four-wheel drive vehicle, it is possible to suppress the slip of the rear wheels at which the ground contact load decreases during traction and acceleration.

The four-wheel drive vehicle which is a towing vehicle to which the driving force distribution control system of the vehicle according to the first and second embodiments of the present invention is applied and the trailer which is a towed vehicle are shown, and the force acting on them at the time of towing is shown. It is a schematic side view for demonstrating the concept of. It is a top view which shows the schematic structure of the four-wheel drive vehicle provided with the driving force distribution control system of the vehicle by 1st Embodiment of this invention. It is a block diagram of the driving force distribution control system of the vehicle by 1st Embodiment of this invention. It is a flowchart which shows the control process executed by the driving force distribution control device of the driving force distribution control system of the vehicle by 1st Embodiment of this invention. It is a diagram which shows the relationship between the driving force distribution amount to a rear wheel controlled by the driving force distribution control device of the driving force distribution control system of the vehicle by 1st Embodiment of this invention, and the required acceleration. It is a time chart which shows the time change of the parameter about the driving force distribution control in the driving force distribution control system of the vehicle by 1st Embodiment of this invention. It is a top view which shows the schematic structure of the four-wheel drive vehicle provided with the driving force distribution control system of the vehicle according to the 2nd Embodiment of this invention. It is a block diagram of the driving force distribution control system of the vehicle by 2nd Embodiment of this invention. It is a flowchart which shows the control process executed by the driving force distribution control device of the driving force distribution control system of the vehicle by 2nd Embodiment of this invention. It is a diagram which shows the relationship between the driving force distribution amount to the front wheel controlled by the driving force distribution control device of the driving force distribution control system of the vehicle by 2nd Embodiment of this invention, and the required acceleration. It is a time chart which shows the time change of the parameter about the driving force distribution control in the driving force distribution control system of the vehicle by 2nd Embodiment of this invention.

Hereinafter, the vehicle driving force distribution control system according to the embodiment of the present invention will be described with reference to the accompanying drawings.
First, with reference to FIG. 1, the reduction of the ground contact load of the rear wheels of the vehicle when the vehicle (towing vehicle) is towing the trailer (towed vehicle) and the vehicle is accelerating will be described. FIG. 1 shows a four-wheel drive vehicle which is a towing vehicle to which the vehicle driving force distribution control system according to the first and second embodiments of the present invention is applied, and a trailer which is a towed vehicle, and they are shown at the time of towing. It is a schematic side view for demonstrating the concept of the force acting on.

As shown in FIG. 1, the trailer T is connected to the rear part of the vehicle V via a coupler H formed by a hitch member provided at the rear part of the towed vehicle V and a coupler of the towed vehicle T. In the present embodiment, the trailer T is a two-axle, four-wheel trailer, and its center of gravity G is assumed to be located between the two axes in the front-rear direction of the trailer, as shown in FIG.

When the vehicle V is accelerating, an inertial force acts on the center of gravity G of the trailer T to be pulled, causing a load transfer to the trailer T, and as a result, a pitching moment that tilts the trailer T backward around the center of gravity G. M is produced. That is, due to such a pitching moment M, the trailer T tends to sink in the rear portion and rise in the front portion.
Due to the force that the front portion of the trailer T tends to lift, a force F _H that points upward in the vertical direction of the vehicle V is applied to the coupler H (hitch point). This force F _H is transmitted to the rear part of the vehicle V, and the vehicle V generates a force F2 that raises the rear part and a force F1 that relatively sinks the front part thereof. Among them, the force F2 that causes float the rear of the vehicle V, reduces the ground contact load on the road surface of the rear wheel W _R, the reduced amount, easily rear wheel W _R slip occurs. On the other hand, the vertical load of the front wheel W _F is increased.

Further, in the coupler H which is a hitch point, as shown in FIG. 1, the coupler on the towed vehicle T side is at a position higher than the hitch member on the vehicle side, and in particular, the weight of the towed vehicle T is the weight of the vehicle V. _{If it is larger, the upward force F H} of the vehicle V applied to the coupler H (hitch point) in the vertical direction becomes larger. That is, when the height of the hitch member of the vehicle V and the height of the coupler of the towed vehicle T are combined and connected in the vertical direction, an additional force F _{H due to the difference in height and / or the difference in weight between them.} 'Adds to the coupler H. This force F _{H'is a} constant value during traveling, and the rear portion of the vehicle V is lifted by that amount.

In the first and second embodiments of the present invention described below, such a vehicle V is provided by the vehicle driving force distribution control system 1 (see FIGS. 2 and 7) applied to the four-wheel drive vehicles 2 and 102. wheel W _R after, wheels W _R after due to a decrease in vertical load 8,108, so as to suppress the slip of 8,108. As a modification of the trailer T, if the trailer applies an upward force to the coupler H during acceleration, the trailer does not have the above-mentioned two-axis four-wheel and does not have the above-mentioned center of gravity position. It may be a trailer.

Next, with reference to FIG. 2, a schematic configuration of a four-wheel drive vehicle including a vehicle driving force distribution control system according to the first embodiment of the present invention will be described. FIG. 2 is a plan view showing a schematic configuration of a four-wheel drive vehicle including a vehicle driving force distribution control system according to the first embodiment of the present invention.
As shown in FIG. 2, the vehicle driving force distribution control system 1 according to the present embodiment is applied to the four-wheel drive vehicle 2.

First, the four-wheel drive vehicle 2 includes left and right front wheels 6 as main drive wheels and left and right rear wheels 8 as auxiliary drive wheels, and the driving force of the front wheels 6 is combined with a coupling device (driving force distribution device) 10. It is a so-called FF (front engine front drive) -based four-wheel drive vehicle that is distributed to the rear wheels 8.
Here, the coupling device 10 is controlled by an ECU (Electronic Control Unit) 4 (see FIG. 3 and the like), and the ECU 4 corresponds to the "driving force distribution control device" in the present invention. It corresponds to the "driving force distribution device" in the present invention. The control of the coupling device 10 is executed by the circuit in the ECU 4.

Next, in the four-wheel drive vehicle 2, the engine 12, the transmission 14, and the front wheel differential 18 that distributes the driving force transmitted from the engine 12 to the left and right front wheels 6 via the front wheel drive shaft 16 And.
The four-wheel drive vehicle 2 further includes a transfer 22 that distributes the driving force of the engine 12 to the rear wheel 8 side via the propeller shaft 20, a coupling device 10 connected to the propeller shaft 20, and the coupling device 10. It includes a rear wheel differential 26 that is connected and distributes the driving force distributed by the coupling device 10 to the left and right rear wheels via the rear wheel drive shaft 24.

The coupling device 10 has a wet multi-plate clutch (not shown) for connecting and disconnecting the propeller shaft 20 and the rear wheel differential 26, the input side of which is connected to the propeller shaft 20, and the output side. It is connected to the rear wheel differential 26. In the present embodiment, the coupling device 10 is an electronically controlled coupling whose operation is controlled by the ECU 4, and the front wheels 6 and the rear wheels are controlled by controlling the fastening force between the plurality of friction plates of the wet multi-plate clutch. The driving force (driving torque) distribution amount of 8 is controlled.
The torque distribution (front wheel: rear wheel) in the present embodiment is controlled from the basic 100: 0 to, for example, 50:50 according to the slip state of the front and rear wheels.

Here, the basic control concept of the driving force distribution control by the coupling device 10 according to the present embodiment will be described.
First, in the present embodiment, the driving force is distributed to the front and rear wheels 6 and 8 with a driving force distribution amount that suppresses such a slip state according to the slip state of the front and rear wheels with respect to the road surface. There is. In the present embodiment, the slip state means that the front and rear wheels 6 and 8 slip on the road surface, for example, when traveling on a low μ road surface such as a snowy road or a wet road surface, when traveling uphill or downhill, or when escaping from a concave road surface. It is assumed that slipping will occur.
Further, as a modification, for example, the energy loss in the front wheel 6 caused by the slip of the front wheel 6, the energy loss in the rear wheel 8 caused by the slip of the rear wheel 8, and the rear wheel 8 via the coupling device 10. The driving force distribution amount of the front and rear wheels 6 and 8 may be controlled so that the total amount of the three energy losses of the mechanical energy loss of the driving system due to the transmission of the driving force to the vehicle is reduced.
As a further modification, the amount of driving force distributed to the front and rear wheels 6 and 8 is controlled in consideration of energy loss due to heat generation of a plurality of friction plates of the coupling device 10 so as to prevent excessive heat generation of the coupling device 10. You may.

Next, the control block of the vehicle driving force distribution control system according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of a vehicle driving force distribution control system according to the first embodiment of the present invention.
As shown in FIG. 3, the ECU 4 includes a microcomputer (not shown), a memory, an I / F circuit, and the like (not shown).
In the present embodiment, the ECU 4 has an output signal relating to ON / OFF of the traction mode from the traction mode switch 30 which is provided near the driver's seat of the vehicle and can be manually selected by the driver, and an accelerator pedal from the accelerator opening sensor 32. An output signal related to the opening degree, an output signal for detecting the slip state of the front wheel 6 from the front wheel speed sensor 34 for detecting the rotation speed of the front wheel 6, and a rear wheel speed sensor 36 for detecting the rotation speed of the rear wheel 8. An output signal for detecting the slip state of the wheel 8, an output signal for determining whether or not the towed vehicle from the actual traction sensor 38 which is an energization sensor of the coupler H is connected, and an engine rotation speed sensor 40. Output signal relating to the rotation speed of the engine 12 from, the output signal relating to the rotation speed of the input shaft of the transmission 14 from the transmission input shaft rotation speed sensor 42, and the transmission 14 from the transmission output shaft rotation speed sensor 44. Output signals related to the number of rotations of the output shaft are input respectively.

The output signal relating to the opening degree of the accelerator pedal is a signal that outputs a numerical value corresponding to the amount of depression of the accelerator pedal by the driver, and the ECU 4 calculates the required acceleration of the driver based on this output signal.
Further, the ECU 4 calculates a value related to the reduction ratio in the transmission 14 based on the output signals from the transmission input shaft rotation speed sensor 42 and the transmission output shaft rotation speed sensor 44.
The ECU 4 is connected to the coupling device 10 and controls the coupling device 10 based on each output signal, as will be described later. That is, the ECU 4 outputs a command value regarding the driving force distribution of the front and rear wheels (torque distribution ratio of the front and rear wheels) to the coupling device 10, and the coupling device 10 outputs the command values of the front and rear wheels 6 and 8 based on the command value. It is controlled to distribute the driving force. Further, as will be described later, the ECU 4 calculates the coupling transmission torque in the coupling device 10 based on the command value related to the driving force distribution and the like.

Next, the control contents of the vehicle driving force distribution control system according to the first embodiment of the present invention will be described with reference to FIGS. 4 to 6. FIG. 4 is a flowchart showing a control process executed by the driving force distribution control device of the driving force distribution control system of the vehicle according to the first embodiment of the present invention, and FIG. 5 is a flowchart showing the vehicle according to the first embodiment of the present invention. FIG. 6 is a diagram showing the relationship between the amount of driving force distributed to the rear wheels controlled by the driving force distribution control device of the driving force distribution control system and the required acceleration, and FIG. 6 is a diagram showing the relationship between the vehicle according to the first embodiment of the present invention. It is a time chart which shows the time change of the parameter about the driving force distribution control in the driving force distribution control system of. In FIG. 4, S indicates each step.

First, as shown in FIG. 4, the ECU 4 (driving force distribution control device) acquires output signals from the above-mentioned switches / sensors 30, 32, 34, 36, 38, 40, 42, 44 in S1. .. Further, the ECU 4 acquires a command value related to the driving force distribution of the front and rear wheels output from the ECU 4 to the coupling device 10 at the time of S1 as a signal. Further, in S1, the ECU 4 reads out the respective values of the vehicle weight, the front wheel radius, and the rear wheel radius as the vehicle specifications (fixed values) stored in the memory in the ECU 4. Further, the ECU 4 reads out the engine specifications stored in the memory in the ECU 4 that define the relationship between the engine speed and the engine torque.

Next, the process proceeds to S2, and the estimated ground contact load of the rear wheels is calculated.
Specifically, in S2, the ECU 4 first calculates the value of the engine torque output from the engine 12 from the engine speed and engine specifications acquired in S1. The ECU 4 further calculates the value of the gear ratio of the transmission 14 from the rotation speeds of the input shaft and the output shaft of the transmission 14 acquired in S1. The ECU 4 further calculates the torque output from the transmission 14 based on the calculated engine torque value and gear ratio value. The ECU 4 further calculates the coupling transmission torque in the coupling device 10 based on the output torque from the transmission 14 and the command value related to the driving force distribution of the front and rear wheels acquired in S1.
Then, the ECU 4 calculates the estimated ground contact load of the rear wheels in S2 based on the calculated value of the coupling transmission torque and each value of the vehicle specifications read in S1.

Next, the process proceeds to S3, and it is determined whether or not the four-wheel drive vehicle 2 is towing the towed vehicle T (see FIG. 1). This determination is basically executed based on whether or not an output signal relating to ON / OFF of the traction mode is detected by the driver operating the traction mode switch 30 described above. In the present embodiment, the presence or absence of an energization signal of the energization sensor 38 (actual traction sensor 38 in FIG. 3) provided in the coupler H (hitch point) is further detected, and when the energization signal is ON, that is, actually. When the towed vehicle T is connected, it receives an ON signal operated by the driver's tow mode switch 30 and determines that the towed vehicle T is towed.
In the present embodiment, in this way, when the driver selects the towing driving mode, the correction processing of S4 and S5 is performed so as to suppress the driver's discomfort and the towing is actually performed. During this time, it is determined that the towed vehicle is being towed, and the processes of S4 and S5 at the time of towing are executed more effectively.

Next, in S3, when it is determined that the traction time is in effect, the process proceeds to S4, and the traction time correction coefficient is first determined as the traction time processing. This traction correction coefficient is a coefficient for correcting the estimated ground contact load calculated in S2 (correction is executed in S5).
In this S4, as the first correction coefficient, the vehicle weight (fixed value), the wheelbase of the vehicle (fixed value), the distance between the rear wheel and the coupler H (hitch point), and the weight of the towed vehicle T. The correction coefficient is determined based on (fixed value) and the required acceleration of the driver in the vehicle.

In the first embodiment, as shown in FIG. 5, such a correction coefficient is shown by a solid line with respect to the basic driving force distribution amount to the rear wheels 8 in the normal state (during non-traction) shown by the alternate long and short dash line. In addition, the larger the required acceleration of the driver, the smaller the amount of driving force distributed to the rear wheels 8. As an example, at a certain required acceleration A, a traction correction amount B that reduces the driving force distribution amount of the rear wheels is obtained. The amount of driving force distributed to the rear wheels 8 as shown in FIG. 5 is determined in S7.

Here, the above-mentioned basic drive distribution amount is appropriately determined by the ECU 4 based on the road surface condition, heat generation of the coupling device 10, and the like during normal driving during towing and / or non-acceleration, for example. It is the amount of distribution. For example, in the following, front wheel: rear wheel = 80:20.

Next, as the second correction coefficient, when the required acceleration of the driver is 0, the correction coefficient is set to 1, and as shown in FIG. 5, the amount of driving force distributed to the rear wheels during traction is the same as in the normal case. To be.

Next, as the third correction coefficient, the correction coefficient is determined as described above at the time of the previous processing of the processing of S4, and at the time of the current processing with respect to the required acceleration of the driver at the time of the previous processing. When the required acceleration of the driver is increasing or decreasing, the incremental correction coefficient for obtaining the increasing correction amount or the decreasing correction amount corresponding to the difference of the required acceleration is determined with respect to the previous correction amount (B). You may.
Further, as the fourth correction coefficient, the correction coefficient has already been determined as described above at the time of the previous processing of S4, and the driver at the time of this processing has a response to the required acceleration of the driver at the time of the previous processing. If the required acceleration has not changed, the correction coefficient may be set to 1 so that the same correction amount (B) as in the previous processing may be obtained.

In addition, in order to clarify the concept of the correction amount at the time of towing, FIG. 5 linearly shows the degree of decrease of the driving force distribution amount with respect to the required acceleration at the time of towing. It may be non-linear depending on the characteristics of the device, the specifications of the towed vehicle T, the magnitude of the required acceleration, and the like.

Next, in S5, the estimated ground contact load of the rear wheels calculated in S2 is multiplied by the traction correction coefficient determined in S4. That is, in S5
Estimated ground contact load after correction (S5) = Estimated ground contact load (S2) x correction coefficient (S4)
And calculate.

Next, in S6, the estimated slip limit load of the rear wheels is calculated. Specifically, the estimated slip limit load of the rear wheels is calculated by multiplying the corrected estimated ground contact load calculated in S5 by the slip limit gain, which is a predetermined value predetermined by an experiment or the like. The slip limit gain is stored in the ECU 4 as a map corresponding to the road surface μ.

Next, in S7, the driving force distribution amount of the rear wheels 8 that does not exceed the estimated slip limit load of the rear wheels calculated in S6 is determined, and the cup is obtained so that the determined driving force distribution amount of the rear wheels 8 can be obtained. Controls the ring device 10. In this S7, the driving force distribution amount of the rear wheels 8 is determined based on the driving force distribution ratio at the time of traction (for example, front wheels: rear wheels = 90:10).

On the other hand, if it is determined in S3 that it is not in traction, in S6, the estimated slip limit load of the rear wheels calculated in S2 is multiplied by the slip limit gain described above to obtain the estimated slip limit load of the rear wheels. The coupling device is calculated, and in S7, the driving force distribution amount of the rear wheels that does not exceed the estimated slip limit load of the rear wheels calculated in S6 is determined, and the determined driving force distribution amount of the rear wheels is obtained. 10 is controlled. In this S7, the driving force distribution amount of the rear wheels is determined based on the basic driving force distribution ratio at the normal time (for example, front wheels: rear wheels = 80:20).

Next, as shown in the chart (a) of FIG. 6, when the required acceleration of the driver starts to increase from a certain time t1, as shown in the chart (b), the towed vehicle corresponds to the amount of increase in the acceleration. The load F _H received from T also increases, and the dynamic ground contact load of the rear wheels decreases due to the increase in the _{load F H.}
On the other hand, in the present embodiment, as described above, the larger the required acceleration of the driver, the smaller the amount of driving force distributed to the rear wheels 8 is corrected, and as shown in the chart (c), the driving force of the rear wheels 8 is corrected. I am trying to reduce. As a result, the rear wheel 8 is prevented from slipping even if the dynamic ground contact load is reduced.
As shown in the chart (d), the driving force of the front wheels increases by the amount corrected so that the amount of driving force distributed to the rear wheels 8 becomes smaller.

Next, with reference to FIG. 7, a schematic configuration of a four-wheel drive vehicle including a vehicle driving force distribution control system according to a second embodiment of the present invention will be described. FIG. 7 is a plan view showing a schematic configuration of a four-wheel drive vehicle including a vehicle driving force distribution control system according to a second embodiment of the present invention. In the second embodiment described below, the same configurations as those in the first embodiment described above will be described with the same reference numerals.
As shown in FIG. 7, the vehicle driving force distribution control system 1 according to the second embodiment is composed of a four-wheel drive vehicle 102 and an ECU (driving force distribution control device) 104.

First, the four-wheel drive vehicle 2 includes left and right rear wheels 108 as main drive wheels and left and right front wheels 106 as auxiliary drive wheels, and the driving force of the rear wheels 108 is coupled to a coupling device (driving force distribution device). It is a so-called FR (front engine rear drive) -based four-wheel drive vehicle that is distributed to the front wheels 106 by 110.
As in the first embodiment described above, the coupling device 110 is controlled by an ECU (Electronic Control Unit) 104, which corresponds to the "driving force distribution control device" in the present invention and is a coupling device. 110 corresponds to the "driving force distribution device" in the present invention. The control of the coupling device 110 is executed by the circuit in the ECU 104.

Next, the four-wheel drive vehicle 102 includes an engine 112 as a drive source, a transmission 114, and a transfer 122 for transmitting the driving force of the engine 12 to the rear wheel 8 side via the rear wheel propeller shaft 120. The rear wheel differential 126, which is connected to the rear wheel propeller shaft 120 and distributes the transmitted driving force to the left and right rear wheels via the rear wheel drive shaft 124, is provided.

The four-wheel drive vehicle 102 is further connected to a rear wheel propeller shaft 120, and is connected to a coupling device 110 that distributes the driving force transmitted to the rear wheels 108 to the front wheels 106 side, and the coupling device 110. It includes a front wheel propeller shaft 111 that transmits the distributed driving force to the front wheel side, and a front wheel differential 118 that distributes the transmitted driving force to the left and right front wheels 106 via the front wheel drive shaft 116.

The coupling device 110 has a wet multi-plate clutch (not shown) for connecting and disconnecting the rear wheel propeller shaft 120 and the front wheel propeller shaft 11 so that the input side thereof is the rear wheel propeller shaft 120. The output side is connected to the front wheel propeller shaft 111. The coupling device 10 is an electronically controlled coupling whose operation is controlled by the ECU 104, as in the first embodiment described above, and controls the fastening force between a plurality of friction plates of the wet multi-plate clutch. The amount of driving force (driving torque) distributed between the rear wheels 108 and the front wheels 106 is controlled.
The torque distribution (front wheels: rear wheels) in the present embodiment is controlled from the basic 0: 100 to, for example, 50:50 according to the slip state of the front and rear wheels.

Here, also in the second embodiment, as in the first embodiment described above, the front and rear wheels have a driving force distribution amount that suppresses such a slip state according to the slip state of the front and rear wheels with respect to the road surface. The driving force is distributed to 6 and 8.
Further, as a modification, for example, the energy loss in the front wheel 6 caused by the slip of the front wheel 6, the energy loss in the rear wheel 8 caused by the slip of the rear wheel 8, and the rear wheel 8 via the coupling device 10. The driving force distribution amount of the front and rear wheels 6 and 8 may be controlled so that the total amount of the three energy losses of the mechanical energy loss of the driving system due to the transmission of the driving force to the vehicle is reduced.
As a further modification, the amount of driving force distributed to the front and rear wheels 6 and 8 is controlled in consideration of energy loss due to heat generation of a plurality of friction plates of the coupling device 10 so as to prevent excessive heat generation of the coupling device 10. You may.

Next, the control block of the vehicle driving force distribution control system according to the second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a block diagram of a vehicle driving force distribution control system according to a second embodiment of the present invention.
As shown in FIG. 8, similarly to the first embodiment described above, the ECU 4 has an output signal regarding ON / OFF of the traction mode from the traction mode switch 30 that can be manually selected by the driver, and an accelerator opening sensor 32. Output signal related to the accelerator pedal opening, the output signal for detecting the slip state of the front wheel 6 from the front wheel speed sensor 34 for detecting the rotation speed of the front wheel 6, and the rear wheel speed sensor 36 for detecting the rotation speed of the rear wheel 8. Output signal for detecting the slip state of the rear wheel 8 from, output signal for determining whether or not the towed vehicle from the actual traction sensor 38 which is the energization sensor of the coupler H is connected, engine rotation An output signal regarding the rotation speed of the engine 112 from the number sensor 40, an output signal regarding the rotation speed of the input shaft of the transmission 114 from the transmission input shaft rotation speed sensor 42, and a shift from the transmission output shaft rotation speed sensor 44. Output signals related to the number of rotations of the output shaft of the machine 114 are input respectively.

The output signal relating to the opening degree of the accelerator pedal is a signal that outputs a numerical value corresponding to the amount of depression of the accelerator pedal by the driver, and the ECU 104 calculates the required acceleration of the driver based on this output signal.
Further, the ECU 104 calculates a numerical value related to the reduction ratio in the transmission 114 based on the output signals from the transmission input shaft rotation speed sensor 42 and the transmission output shaft rotation speed sensor 44.
The ECU 104 is connected to the coupling device 110 and controls the coupling device 110 based on each output signal, as will be described later. That is, the ECU 4 outputs a command value regarding the distribution of the driving force of the front and rear wheels to the coupling device 110, and the coupling device 110 is controlled to distribute the driving force of the front and rear wheels 106 and 108 based on this command value. NS. Further, as will be described later, the ECU 104 calculates the coupling transmission torque in the coupling device 110 based on the command value related to the driving force distribution and the like.

Next, the control contents of the vehicle driving force distribution control system according to the second embodiment of the present invention will be described with reference to FIGS. 9 to 11. FIG. 9 is a flowchart showing a control process executed by the driving force distribution control device of the driving force distribution control system of the vehicle according to the second embodiment of the present invention, and FIG. 10 is a flowchart showing the vehicle according to the second embodiment of the present invention. FIG. 11 is a diagram showing the relationship between the amount of driving force distributed to the rear wheels controlled by the driving force distribution control device of the driving force distribution control system and the required acceleration, and FIG. 11 is a diagram showing the vehicle according to the second embodiment of the present invention. It is a time chart which shows the time change of the parameter about the driving force distribution control in the driving force distribution control system of. In FIG. 9, S indicates each step.

First, as shown in FIG. 9, the ECU 104 (driving force distribution control device) has the above-mentioned switches / sensors 30, 32, 34, 36, 38, 40, in S1 as in the first embodiment described above. The output signals from 42 and 44 and the signal of the command value related to the driving force distribution of the front and rear wheels are acquired, and the values of the vehicle specifications and the engine specifications are read out. Calculate the estimated ground contact load.

Next, the process proceeds to S3, and similarly to the first embodiment described above, it is determined whether or not the four-wheel drive vehicle 2 is towing the towed vehicle T (see FIG. 1). If it is determined, the process proceeds to S4, and as a process at the time of towing, first, a correction coefficient at the time of towing is determined. This traction correction coefficient is a coefficient for correcting the estimated ground contact load calculated in S2 (correction is executed in S5).
In this S4, as the first correction coefficient, the vehicle weight (fixed value), the wheelbase of the vehicle (fixed value), the distance between the rear wheel and the coupler H (hitch point), and the weight of the towed vehicle T. The correction coefficient is determined based on (fixed value) and the required acceleration of the driver in the vehicle.

In the second embodiment, as shown in FIG. 10, the larger the required acceleration of the driver with respect to the basic driving force distribution amount to the front wheels 106 during the normal operation (non-traction) indicated by the alternate long and short dash line, the more to the front wheels 106. It is corrected so that the driving force distribution amount becomes large. As an example, at a certain required acceleration A, a traction correction amount C that increases the driving force distribution amount of the front wheels is obtained. The driving force distribution amount of the front wheels 106 is determined in S7.

More specifically, the second embodiment is the driving force distribution control system 1 applied to the FR-based four-wheel drive vehicle 102. Therefore, for example, the basic front wheel: rear wheel = 0: 100 distribution ratio. Therefore, by increasing the amount of driving force distributed to the front wheels 106, the driving force distribution to the rear wheels 108 is relatively reduced, and as a result, the rear wheels due to the decrease in the dynamic ground contact load of the rear wheels 108. The slip of 108 is suppressed.

The basic drive distribution amount in the second embodiment is the driving force distribution amount appropriately determined by the ECU 104 during normal driving during towing and / or non-acceleration, for example, as in the first embodiment described above. For example, in the following, front wheel: rear wheel = 0: 100.

Next, as the second correction coefficient, when the required acceleration of the driver is 0, the correction coefficient is set to 1, and as shown in FIG. 10, the amount of driving force distributed to the front wheels during traction is the same as in the normal case. To be.

Next, as the third correction coefficient, the correction coefficient is determined as described above at the time of the previous processing of the processing of S4, and at the time of the current processing with respect to the required acceleration of the driver at the time of the previous processing. When the required acceleration of the driver is increasing or decreasing, the incremental correction coefficient for obtaining the increasing correction amount or the decreasing correction amount corresponding to the difference of the required acceleration is determined with respect to the previous correction amount (C). You may.
Further, as the fourth correction coefficient, the correction coefficient is determined as described above at the time of the previous processing of the S4 processing, and the driver at the time of the current processing with respect to the required acceleration of the driver at the time of the previous processing. If the required acceleration of is not changed, the correction coefficient may be set to 1 and the same correction amount (C) as in the previous process may be obtained.

In addition, in order to clarify the concept of the correction amount at the time of towing, FIG. 10 linearly shows the degree of increase of the driving force distribution amount with respect to the required acceleration at the time of towing. It may be non-linear depending on the characteristics of the device, the specifications of the towed vehicle T, the magnitude of the required acceleration, and the like.

Next, as in the first embodiment described above, in S5, the estimated ground contact load of the rear wheels calculated in S2 is multiplied by the correction coefficient determined in S4, and in S6, the estimated slip limit of the rear wheels. Calculate the load.

Next, in S7, in the second embodiment, the driving force distribution amount of the rear wheels that does not exceed the estimated slip limit load of the rear wheels 108 calculated in S6 is first determined, and the determined driving force distribution of the rear wheels is determined. From the amount, the amount of driving force distributed to the front wheels 106 is determined. Then, in S7, the coupling device 110 is controlled so that the determined driving force distribution amount of the front wheels 106 can be obtained. In this S7, the driving force distribution amount of the front wheels 106 is determined based on the driving force distribution ratio during traction (for example, front wheels: rear wheels = 10:90).

On the other hand, if it is determined in S3 that it is not in traction, the estimated slip limit load of the rear wheels is calculated by multiplying the estimated ground contact load of the rear wheels calculated in S2 by the slip limit gain in S6. In S7, the driving force distribution amount of the front wheels is determined so as to be the driving force distribution amount of the rear wheels that does not exceed the estimated slip limit load of the rear wheels calculated in S6, and the determined driving force distribution amount of the front wheels is obtained. The coupling device 110 is controlled so as to be used. In this S7, the driving force distribution amount of the front wheels 106 is determined based on the basic driving force distribution ratio at the normal time (for example, front wheels: rear wheels = 0: 100).

Next, as shown in the chart (a) of FIG. 11, when the required acceleration of the driver starts to increase from a certain time t1, the load F _H received from the towed vehicle T according to the amount of increase in the acceleration (FIG. 1). (See) Increasing, and due to the increase in its load F _H , the dynamic ground contact load of the rear wheels 108 decreases, as shown in chart (b).
On the other hand, in the second embodiment, as described above, the larger the required acceleration of the driver, the larger the amount of driving force distributed to the front wheels 106 is corrected (chart (d)), and the rear wheels 108 are relatively. The driving force is reduced (chart (c)). As a result, even if the dynamic contact load of the rear wheels 108 is reduced, the rear wheels 108 are prevented from slipping.

Next, the action and effect according to the embodiment of the present invention will be described.
The vehicle driving force distribution control system 1 according to the first and second embodiments of the present invention is a driving force distribution device that distributes the driving force of the front and rear wheels 6, 8, 106, 108 of the four-wheel drive vehicle V, 2, 102. A four-wheel drive vehicle is provided with 10, 110 and ECUs (driving force distribution control devices) 4, 104 for controlling the driving force distribution amount of the front and rear wheels by the driving force distribution device. The ECUs 4 and 104 are provided with a traction determination means for determining whether or not the towing vehicle is being towed and a required acceleration detecting means for detecting the required acceleration of the driver in the four-wheel drive vehicle. The ECUs 4 and 104 are towed by the four-wheel drive vehicle. When it is determined that the vehicle is being towed and the required acceleration of the driver is detected, the larger the required acceleration of the driver, the smaller the amount of driving force distributed to the rear wheels 8 and 108 of the four-wheel drive vehicle. It is configured to control the driving force distribution device.
As a result, when the towed vehicle (four-wheel drive vehicle) V, 2, 102 is accelerated, the towed vehicle T is tilted backward in a side view due to the inertial force, and the front part of the towed vehicle T is lifted. As a result, even if the rear parts of the four-wheel drive vehicles V, 2 and 102 that are connected are raised and the ground contact load of the rear wheels 8 and 108 decreases, the larger the driver's required acceleration, the more to the rear wheels 8 and 108. The driving force distribution can be reduced to reduce the driving torque transmitted from the rear wheels 8 and 108 to the road surface. Therefore, it is possible to suppress slippage of the rear wheels 8 and 108, which reduce the ground contact load during traction and acceleration.

Further, according to the first and second embodiments of the present invention, the ECUs (driving force distribution control devices) 4 and 104 have basic driving force distribution ratios (for example, for example) of the front and rear wheels during non-traction and / or non-acceleration. A distribution ratio that suppresses slipping that depends on the road surface μ, etc., and a distribution ratio that reduces heat generation and energy loss when the driving force distribution devices 10 and 110 are coupling devices using a plurality of friction plates, etc.) Is determined, the basic driving force distribution ratio is corrected during traction and acceleration, the driving force distribution amount to the rear wheels 8 and 108 is calculated based on the corrected driving force distribution ratio, and the driving force distribution device is used. Since 10 and 110 are controlled, the slip of the rear wheels 8 and 108 can be suppressed more effectively.

Further, according to the first embodiment of the present invention, in the four-wheel drive vehicle V2, the front wheels 6 are the main driving wheels, and the driving force of the front wheels is transferred to the rear wheels 8 by the driving force distribution device 10. It is a so-called FF (front engine front drive) based four-wheel drive vehicle that distributes, and the larger the driver's required acceleration, the smaller the amount of driving force distributed to the rear wheels 8 of the four-wheel drive vehicle, so it is effective. , The slip of the rear wheel 8 can be suppressed.

Further, according to the second embodiment of the present invention, in the four-wheel drive vehicle V, 102, the rear wheels 108 are the main driving wheels, and the driving force of the rear wheels is transferred to the front wheels 6 by the driving force distribution device 110. It is a so-called FR (front engine rear drive) -based four-wheel drive vehicle that distributes, and the larger the driver's required acceleration, the larger the amount of driving force distributed to the front wheels 106 of the four-wheel drive vehicle. By increasing the amount of driving force distributed to the rear wheels 108, the amount of driving force distributed to the rear wheels 108 can be reduced, which effectively suppresses the slip of the rear wheels 108.

V four-wheel drive vehicle (towing vehicle)
T trailer (towed vehicle)
G Center of gravity of towed vehicle H Coupler (connector)
F force, load M moment 1 Vehicle driving force distribution control system 2,102 Four-wheel drive vehicle 4,104 ECU (driving force distribution control device)
6, 106, W _F front wheels 8, 108, W _R rear wheel 10, 110 coupling device (driving force distribution device)

Claims (6)

It is a vehicle driving force distribution control system that controls the distribution amount of the driving force of the front and rear wheels in a four-wheel drive vehicle that can tow a towed vehicle.
A driving force distribution device that distributes the driving force of the front and rear wheels of the four-wheel drive vehicle,
The driving force distribution control device for controlling the driving force distribution amount of the front and rear wheels by the driving force distribution device is provided.
The driving force distribution control device is
A towing determination means for determining whether or not the four-wheel drive vehicle is towing the towed vehicle,
The four-wheel drive vehicle is provided with a required acceleration detecting means for detecting the required acceleration of the driver.
In the driving force distribution control device, when it is determined by the traction determination means that the four-wheel drive vehicle is towing the towed vehicle and the required acceleration of the driver is detected by the required acceleration detecting means. The driving force of the vehicle is configured to control the driving force distribution device so that the larger the required acceleration of the driver is, the smaller the amount of driving force distributed to the rear wheels of the four-wheel drive vehicle is. Allocation control system. The driving force distribution control device is
When it is determined by the traction determination means that the four-wheel drive vehicle is not towing the towed vehicle and / or the required acceleration of the driver is not detected by the required acceleration detecting means, the four-wheel drive vehicle Basic driving force distribution ratio determining means for determining the basic driving force distribution ratio for the front and rear wheels,
When it is determined by the traction determination means that the four-wheel drive vehicle is towing the towed vehicle and the required acceleration of the driver is detected by the required acceleration detecting means, the basic driving force distribution ratio determining means. It has a driving force distribution ratio correcting means for correcting the basic driving force distribution ratio so that the driving force distribution ratio to the rear wheels becomes smaller than the basic driving force distribution ratio of the front and rear wheels determined by
In the driving force distribution control device, when it is determined by the traction determination means that the four-wheel drive vehicle is towing the towed vehicle and the required acceleration of the driver is detected by the required acceleration detecting means. The first aspect of claim 1, wherein the driving force distribution amount to the rear wheels is calculated based on the driving force distribution ratio corrected by the driving force distribution ratio correcting means, and the driving force distribution device is controlled. Vehicle driving force distribution control system. The four-wheel drive vehicle is a four-wheel drive vehicle in which the front wheels are the main driving wheels and the driving force of the front wheels is distributed to the rear wheels by the driving force distribution device.
The driving force distribution control device is configured to control the driving force distribution device so that the larger the required acceleration of the driver, the smaller the amount of driving force distributed to the rear wheels of the four-wheel drive vehicle. 1 or the vehicle driving force distribution control system according to claim 2. The four-wheel drive vehicle is a four-wheel drive vehicle in which the rear wheels are the main driving wheels and the driving force of the rear wheels is distributed to the front wheels by the driving force distribution device.
The driving force distribution control device is configured to control the driving force distribution device so that the larger the required acceleration of the driver, the larger the amount of driving force distributed to the front wheels of the four-wheel drive vehicle. Alternatively, the vehicle driving force distribution control system according to claim 2. Any one of claims 1 to 4, wherein the towing determination means of the driving force distribution control device determines that the four-wheel drive vehicle is towing the towed vehicle when the towing travel mode is selected by the driver. The vehicle driving force distribution control system described in the section. Further, a towed vehicle connection determination device for determining whether or not the non-towed vehicle is connected to a connecting portion provided at the rear of the four-wheel drive vehicle is provided.
The towing determination means of the driving force distribution control device accepts the selection of the towing travel mode by the driver while the towed vehicle connection determination device determines that the towed vehicle is connected, and the four-wheel drive. The vehicle driving force distribution control system according to claim 5, wherein it is determined that the vehicle is towing the towed vehicle.

Images