JP2003306051A - Wheel drive force distribution control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel drive force distribution control system for restraining the heat generation of a torque transmission means even if difference in an outer diameter is generated in front and rear wheels. <P>SOLUTION: In the wheel drive force distribution control system 90, a rotational difference torque command value is determined based on the cancellation of a natural rotary speed difference ΔNh due to the outer diameter difference of the front and rear wheels 14, 15 from a rotary speed difference ΔNi in the front and rear wheels 14, 15 during drive for controlling a transmission torque to the rear wheel 15, thus permitting a drive while the natural rotary speed difference ΔNh is present between the front and rear wheels 14, 15, and restraining the heat generation of the torque-transmitting apparatus 30. Additionally, every time when an automobile becomes steady conditions, the natural rotary speed difference ΔNh to be cancelled is updated, thus also coping with a change in the outer diameter difference in the front and rear wheels 14, 15. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel driving force distribution control system that changes the torque transmitted to wheels other than the constantly driving wheels of an automobile according to the situation.

[0002]

2. Description of the Related Art Recent four-wheel drive vehicles are equipped with a torque transmission device in the middle of a propeller shaft that connects an engine and rear wheels, for example, to drive the front wheels at all times and the rear wheels according to the situation. It has become. Specifically, for example, when the front wheels slip, the torque transmission device controls the transmission of the driving torque to the rear wheels so as to reduce the rotational speed difference between the front and rear wheels. As a result, slip can be suppressed and a rough road can be dealt with.

[0003]

By the way, a rotational speed difference may occur between the front and rear wheels due to causes other than slip. For example, when the outer diameters of the front and rear wheels are different due to wear of tires, difference in tire air pressure, attachment of spare tires, and the like, a difference in rotational speed occurs between the front and rear wheels even when traveling without slipping.

However, in the prior art, even if the difference in rotational speed between the front and rear wheels is due to the difference in outer diameter between the front and rear wheels, control is performed so as to reduce the difference in rotational speed. There was a risk that the device would be overheated due to excessive load.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel driving force distribution control system capable of suppressing heat generation of a torque transmitting means even when an outer diameter difference occurs between front and rear wheels. And

[0006]

SUMMARY OF THE INVENTION A wheel driving force distribution control system according to the invention of claim 1, which is made in order to achieve the above object, is an input unit which is always rotated in association with front and rear driving wheels of an automobile. And a torque transmitting means that has an output unit that constantly rotates in association with wheels other than the driving wheels and that can change the transmission torque from the input unit to the output unit, and front and rear wheels detected by sensors equipped in the vehicle. A transmission torque control unit that controls the transmission torque of the torque transmission unit based on a rotation difference torque command value that is predetermined according to the rotation speed difference between the front and rear wheels, the vehicle speed, and the front and rear wheels. A unique data storage unit that stores a relationship with a unique rotation speed difference caused between the front and rear wheels due to an outer diameter difference, a vehicle speed that can be calculated from the rotation speed when the vehicle travels under predetermined traveling conditions, and a front and rear wheel Rotation speed A unique data update means for updating the stored content of the unique data storage means based on the unique rotational speed difference obtained as a difference, and the transmission torque control means, the traveling vehicle speed and the stored content of the unique data storage means. Based on, obtain the inherent rotational speed difference with respect to the running vehicle speed,
It is characterized in that the rotation difference torque command value is determined based on a value obtained by canceling the inherent rotation speed difference from the rotation speed difference between the front and rear wheels that are running.

The "continuously driven wheel" in the present invention means a wheel which is constantly driven by a driving force when the automobile is running.

According to a second aspect of the present invention, in the wheel drive force distribution control system according to the first aspect, the vehicle speed when traveling under predetermined traveling conditions is Vm, and the natural rotation speed when traveling under predetermined traveling conditions. When the difference is ΔNm, the traveling vehicle speed is Vi, the traveling rotation speed difference is ΔNi, and the characteristic rotation speed difference with respect to the traveling vehicle speed Vi is ΔNh, Vm and ΔNm are stored in the characteristic data storage means. Or
The characteristic is that ΔNm / Vm is stored and the rotation difference torque command value is determined based on ΔNf obtained from ΔNh = Vi · ΔNm / Vm ΔNf = ΔNi−ΔNh.

According to a third aspect of the present invention, in the wheel driving force distribution control system according to the first or second aspect, the predetermined traveling condition is that the throttle opening of the vehicle is equal to or less than a predetermined value and the rotation speeds of the front and rear wheels. The feature is that the change amount of the difference is less than or equal to a certain value, the variation amount of the vehicle speed is less than or equal to a certain value, and the vehicle speed is more than a predetermined value.

[0010]

In the wheel driving force distribution control system of the present invention, the rotation difference torque is based on the difference between the rotation speeds of the front and rear wheels that are running and the inherent rotation speed difference due to the outer diameter difference between the front and rear wheels is canceled. The command value is determined and the transmission torque to wheels other than the constantly driven wheels is controlled. As a result, the vehicle is allowed to travel in the state where there is a difference in the natural rotational speed between the front and rear wheels, and heat generation of the torque transmission means can be suppressed.
Moreover, the canceled specific rotational speed difference is updated every time the vehicle reaches a predetermined traveling condition, so that it is possible to cope with a change in the outer diameter difference between the front and rear wheels.

Specifically, since the difference in the natural rotational speed due to the difference in the outer diameters of the front and rear wheels is proportional to the vehicle speed, the vehicle speed Vm and the natural rotational speed when traveling under a predetermined traveling condition as in the configuration of claim 2. The difference ΔNm is stored in the peculiar data storage means, and the peculiar rotation speed difference ΔNh with respect to the traveling vehicle speed Vi is obtained from the traveling vehicle speed Vi, the stored contents of the peculiar data storage means, and the following equation, and ΔNh = Vi · ΔNm / Vm It is sufficient to determine the rotation difference torque command value based on ΔNf obtained by canceling the specific rotation speed difference ΔNh from the rotation speed difference ΔNi during traveling as in the following equation. ΔNf = ΔNi−ΔNh

According to the third aspect of the invention, the throttle opening of the automobile is less than a predetermined value, the amount of change in the rotational speed difference between the front and rear wheels is less than a fixed value, and the amount of change in the vehicle speed is less than a certain value. If the vehicle speed is equal to or higher than the predetermined value, the content of the unique data storage means is updated. As a result, the rotational speed difference between the front and rear wheels, which is detected when the front and rear wheels are unlikely to slip, can be updated as the inherent rotational speed difference due to the outer diameter difference between the front and rear wheels.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG.
~ It demonstrates based on FIG. FIG. 1 shows a main part of a drive system of an automobile. On the front side (left side in FIG. 1) of this automobile, a trans-askule 11 is provided adjacent to the engine 10.
1, a transmission, a transfer, and a front differential 12 are integrally assembled. Then, the driving force of the engine 10 is transmitted to the front wheel driven shafts 13, 13 via the transmission of the trans-ask 11 and the front differential 12, and the front wheels 14, 14 are driven. That is, in the present embodiment, the front wheels 14 and 14 correspond to the “always-driving wheels” of the present invention which are driven by receiving the driving force when the vehicle is running.

The transmission of the transfer axle 11 gear-connects the transmission with the front end portion of the front propeller shaft 20. A rear end portion of the front propeller shaft 20 is located at an intermediate portion in the front-rear direction of the automobile and serves as an input portion 31 (see FIG. 2) of the torque transmission device 30 (corresponding to “torque transmission means” of the present invention). It is fixed. As a result, the input unit 31 of the torque transmission device 30 constantly rotates in association with the front wheels 14 and 14 as driving wheels.

A rear propeller shaft 21 extends on an extension line of the front propeller shaft 20 with a torque transmission device 30 interposed therebetween, and a front end portion of the rear propeller shaft 21 has an output portion 32 ( (See FIG. 2). Further, the rear end portion of the rear propeller shaft 21 is connected to the rear differential 17, and the rear wheel driven shafts 16, 16 extending from the rear differential 17 in both the left and right directions are attached to the rear wheel 1.
5, 15 are attached. As a result, the output unit 32 of the torque transmission device 30 rotates in conjunction with the rear wheels 15, 15 as "wheels other than the constantly driven wheels" of the present invention.

FIG. 2 shows the basic structure of the torque transmission device 30. The input unit 31 of the torque transmission device 30 is
A cylindrical outer case 33 having a bottom with one end having a bottom wall 33T on the front side (that is, the front side of the automobile) is provided, and at the tip of a shaft portion 33J extending from the center of the bottom wall 33T to the front side, The front propeller shaft 20 (see FIG. 1) is fixed. On the other hand, a rear cover 35 is fitted and screwed to the inside of the open end of the outer case 33, and an inner shaft 34 that constitutes the output portion 32 is liquid-tight in a through hole 35A formed in the center of the rear cover 35. Has penetrated into the state.

The inner shaft 34 is rotatably supported with respect to the outer case 33 with its axial movement restricted, and one end of the inner shaft 34 extends to the inner depth of the outer case 33. The other end projects outward from the outer case 33 and is fixed to the rear propeller shaft 21 (see FIG. 1).

At a position near the rear cover 35 in the outer case 33, a first cam disk 36 is provided with an inner shaft 34.
Is rotatably fitted to the inner pilot clutch plate 37.
Are spline fitted. Also, the outer case 3
A plurality of outer pilot clutch plates 38 are spline-fitted to a position near the rear cover 35 on the inner peripheral surface of 3,
Each inner and outer pilot clutch plate 3
7, 38 are alternately arranged and face each other in the axial direction. Further, a disc-shaped armature 49 is spline-fitted to the inner peripheral surface of the outer case 33 at a position where the group of pilot clutch plates 37 and 38 are sandwiched between the rear cover 35 and the rear cover 35. Further, always, between the armature 49 and the rear cover 35, the inner and outer pilot clutch plates 37, 38 are separated from each other and can freely rotate with respect to each other.

A coil 39 is arranged outside the outer case 33, behind the rear cover 35. The coil 39 is housed inside an annular groove formed on the front surface of an annular yoke 39A, and the yoke 39A is rotatably supported by the rear cover 35 by a bearing (not shown).
Then, by exciting the coil 39, the armature 49
Together with the pilot clutch plates 37 and 38, the rear cover 3
The inner and outer pilot clutch plates 37, 38 are attracted to the No. 5 side and frictionally engage with each other. Also,
As the magnetic force of the coil 39 is increased, the engagement between the pilot clutch plates 37 and 38 deepens, and when the engagement is maximized, the pilot clutch plates 37 and 38 are in a so-called direct connection state in which they are integrally coupled. Due to the frictional engagement or direct connection between the two pilot clutch plates 37 and 38, the first cam disc 36 receives the rotational torque from the outer case 33 and rotates.

V-shaped recesses 40 are formed on the front surface of the first cam disk 36 at a plurality of locations along the circumferential direction. Figure 3
A cross-sectional view of the V-shaped recess 40 as viewed from the radial direction of the first cam disk 36 is shown in (A). As shown in FIG.
The shaped recess 40 is recessed in a V shape so as to become gradually deeper toward the center in the width direction (the vertical direction in FIG. 3A).
Further, the second cam disc 41 is provided on the front side of the first cam disc 36 (the left side in FIGS. 2 and 3 (A)) with the inner shaft 34.
Is spline-fitted to the outer surface of the second cam disk 41, and the second cam disk 41 has a V-shaped recess 40 symmetrical to the V-shaped recess 40 of the first cam disk 36.
A shaped recess 42 is formed. Then, when the cam ball 43 is held by being sandwiched between the both V-shaped recesses 40 and 42, and the first cam disc 36 rotates, FIG.
As shown in FIG. 5, the cam ball 43 moves to a shallow position in the V-shaped recesses 40 and 42, and the first and second cam discs 3
A force is generated in the direction in which the parts 6 and 41 are separated from each other. Further, the first cam disc 36 is restricted from moving in the axial direction by an abutting portion (not shown), so that when the first cam disc 36 rotates, the second cam disc 41 moves forward. Pressed to move.

As shown in FIG. 2, a plurality of inner main clutch plates 44 are spline-fitted to the outer peripheral surface of the inner shaft 34 in front of the second cam disc 41 in the outer case 33, and a plurality of inner main clutch plates 44 are also provided. The outer main clutch plate 45 is spline-fitted to the inner peripheral surface of the outer case 33. The inner and outer main clutch plates 44, 45 are alternately arranged and face each other in the axial direction, and the inner and outer main clutch plates 44, 45 are always separated from each other and freely rotatable. It is in a state of. Then, as described above, the second cam disc 41 moved to the front side due to the magnetic force of the coil 39.
The inner and outer main clutch plates 4
4, 45 are pushed toward the bottom wall 33T side of the outer case 33 and frictionally engage each other, and the main clutch plates 44, 45
Through the outer case 33 to the inner shaft 34
Torque is transmitted to. Further, due to the increase in the magnetic force of the coil 39, the pressing force of the second cam disc 41 increases, and the frictional engagement between the main clutch plates 44 and 45 deepens. When the engagement is deepest, the main clutch plates 44, 45 are in a so-called direct connection state in which they are integrally connected.

In summary, in the torque transmission device 30, the input portion 31 and the output portion 32 allow a freely rotatable mutual disconnection state and a rotation difference between the input portion 31 and the output portion 32. Meanwhile, it is possible to change to a state in which a predetermined torque is transmitted from the input unit 31 to the output unit 32, and further to a direct connection state in which the input unit 31 and the output unit 32 are completely connected.

As shown in FIG. 4, the coil 39 is driven by the ECU 50 ("transmission torque control means" of the present invention).
The ECU 50 and the torque transmission device 30 constitute a wheel driving force distribution control system 90 (see FIG. 1) according to the present invention. ECU
The CPU 70 provided in the 50 includes, for example, a ROM 71, an R
The AM 72, the EEPROM 73 and the drive circuit 74 are connected. Then, as will be described later, the drive circuit 74 drives the coil 39 at a predetermined duty ratio based on the torque command value Ta obtained by the CPU 70, and the torque transmitted by the torque transmission device 30 is adjusted to an appropriate magnitude depending on the situation. To do.
Further, as shown in FIG. 1, the ECU 50 has a throttle opening m detected by the throttle sensor 60 and a rotation speed N of the front wheels 14, 14 detected by the rotation speed sensor 61.
1, N2 and the rotational speeds N3, N4 of the rear wheels 15, 15 are taken in, and the transmission torque of the torque transmission device 30 is determined based on these detection signals.

The ECU 50 takes out the main program M shown in FIG. 5 from the ROM 71 and runs it at a predetermined cycle. As shown in the figure, in the main program M, first, the throttle opening m and the rotational speeds N1 to N4 of the wheels 14, 14, 15, 15 are taken into the ECU 50 (S).
1). Then, the vehicle speed Vi and the rotational speed difference ΔNi between the front and rear wheels are calculated and obtained (S2, S3). Here, the vehicle speed Vi
Is calculated as an average value of the rotational speeds of the rear wheels 15 and 15 which are driven wheels with less slip, as shown in the following equation (S2).

Vi = (N3 + N4) / 2

On the other hand, the rotational speed difference ΔNi is obtained by subtracting the sum of the rotational speeds of the two rear wheels 15 and 15 from the sum of the rotational speeds of the two front wheels 14 and 14 and dividing the result into two, as shown in the following equation. Required (S3).

[0027] ΔNi = (N1 + N2-N3-N4) / 2

Next, a unique data update process (S4) is executed. This processing (S4) corresponds to the "unique data updating means" according to the present invention, and as shown in FIG.
It is checked whether or not the vehicle has become steady (S1)
0). Specifically, when the following four traveling conditions (corresponding to the "predetermined traveling condition" according to the present invention) are satisfied, it is determined that the steady traveling is started, and any one of the following traveling conditions is determined. If the condition is not satisfied, it is determined that the vehicle is not traveling normally.

The throttle opening m of the vehicle is less than or equal to a predetermined value The amount of change in the rotational speed difference ΔNi between the front and rear wheels is less than a certain value The amount of change in the vehicle speed Vi is less than a certain value The vehicle speed Vi is less than a certain value Be above

If it is determined that the vehicle has started to run steadily (Yes in S10), it is checked whether the traveling state determination flag F is 1 (S11). Here, the traveling state determination flag F is provided in the storage area of the RAM 72, and is 0 when the ignition of the vehicle is turned on.
The default setting is. Therefore, the running state determination flag F is 0 when the vehicle starts to run and then enters the steady running for the first time.

When the traveling state determination flag F is 0 (No in S11), after the rotational speed difference ΔNi and the vehicle speed Vi are written in the EEPROM 73 (S1).
2, S13), 1 is set to the traveling state determination flag F (S14). Here, the EEPROM 73 corresponds to the "unique data storage means" according to the present invention, and the EEPROM 73
The rotation speed difference ΔNi (this is the intrinsic rotation speed difference ΔNm) and the vehicle speed Vi (this is the vehicle speed Vm) stored in the EEPROM 7 are stored in the EEPROM 7 even after the key is removed from the automobile.
It is stored in 3. Then, when the vehicle is started to be in a steady running state, the specific rotational speed difference ΔNm and the vehicle speed Vm are updated.

When the main program M is repeatedly executed while the steady running is continued, the running state determination flag F remains 1 (Yes in S11), and the steady running is continued. As long as this is done, the specific rotation speed difference ΔNm and the vehicle speed Vm are not updated, and this processing (S4) is immediately exited.

Further, when the peculiar data updating process (S4) is executed and the vehicle is not in the steady running state (S4)
(No in 10), the traveling state determination flag F is reset to 0, and the process immediately ends (S4).

Returning to the main program M from the unique data updating process (S4), as shown in FIG.
Reads the specific rotational speed difference ΔNm and the vehicle speed Vm from the EEPROM 73, and determines the specific rotational speed difference ΔNh with respect to the traveling vehicle speed Vi based on the following equation (S5).

ΔNh = Vi · ΔNm / Vm

Next, the ECU 50 determines the difference in natural rotation speed Δ
A corrected rotational speed difference ΔNf, which is obtained by canceling Nh from the rotational speed difference ΔNi between the front and rear wheels 14 and 15 while traveling, is obtained based on the following equation (S6).

ΔNf = ΔNi−ΔNh

Next, the pre-torque Tp is calculated (S
7). Specifically, from the map stored in the ROM 71,
Transmission torque T1 corresponding to throttle opening m and vehicle speed V
The gain G1 corresponding to i is determined, and the product of the transmission torque T1 and the gain G1 determines the pre-torque Tp (= G
1.T1) is calculated.

Next, the rotation difference torque Tn (corresponding to the "rotation difference torque command value" according to the present invention) is calculated (S
8). Specifically, from the map stored in the ROM 71,
Transmission torque T corresponding to the above-described corrected rotational speed difference ΔNf
2 and a gain G2 corresponding to the vehicle speed Vi are determined. Then, the rotational difference torque Tn (= G2 · T2) is calculated from the product of the transmission torque T2 and the gain G2.

The above-mentioned gains G1 and G2 are both set to decrease as the vehicle speed Vi increases.

Next, the torque command value Ta (= Tp + Tn) is obtained as the sum of the pre-torque Tp and the rotation difference torque Tn.
Is calculated, and the energization amount to the coil 39 is duty-controlled so that the transmission torque corresponding to the torque command value Ta is transmitted from the input unit 31 of the torque transmission device 30 to the output unit 32 (S9).

The configuration of this embodiment is as described above. Next, the operation and effect of this embodiment will be described. When the accelerator of the automobile is depressed, the throttle opens and the front and rear wheels 14, 15 are driven according to the throttle opening m.

Now, for example, there may be cases where the front and rear wheels 14 and 15 have different degrees of wear, resulting in a difference in outer diameter between the front and rear wheels 14 and 15. In this case, even if the front and rear wheels 14 and 15 travel without slipping, a difference in rotational speed occurs between the front and rear wheels 14 and 15 due to the difference in outer diameter between the front and rear wheels 14 and 15.

However, in the present embodiment, based on the vehicle speed Vi during traveling and the stored contents of the EEPROM 73, the specific rotational speed difference ΔNh due to the outer diameter difference between the front and rear wheels 14 and 15 with respect to the vehicle speed Vi is obtained and detected during traveling. Front and rear wheels 1
From the rotational speed difference ΔNi of 4, 15 to the inherent rotational speed difference Δ
The rotation difference torque Tn is determined based on the corrected rotation speed difference ΔNf in which Nh is canceled. Then, the transmission torque to the rear wheel 15 is controlled based on the rotation difference torque Tn.
As a result, the transmission torque is controlled by setting the state in which there is a difference in the natural rotational speed ΔNh due to the difference in outer diameter between the front and rear wheels 14 and 15 as a normal state, and it is possible to suppress heat generation of the torque transmission means.

Therefore, when any of the front and rear wheels 14, 15 slips, the torque transmission device is adjusted so that the rotation speed difference ΔNi between the front and rear wheels 14, 15 becomes the same as the specific rotation speed difference ΔNh. At 30, the torque is transmitted to the rear wheel 15. As a result, slip can be suppressed and a rough road can be dealt with.

Also, every time the vehicle enters steady running, E
Since the specific rotational speed difference ΔNm and the vehicle speed Vm stored in the EPROM 73 are updated, it is possible to cope with the change in the outer diameter difference between the front and rear wheels 14 and 15.

As described above, according to the wheel driving force distribution control system 90 of the present embodiment, traveling is allowed in a state where the characteristic rotational speed difference ΔNh exists between the front and rear wheels 14 and 15, and the torque transmission device 30 is provided. It is possible to suppress the heat generation of.

As another means for removing the rotational speed difference due to the outer diameter difference between the front and rear wheels 14 and 15, for example, the rotational speed difference ΔNi between the front and rear wheels 14 and 15 detected during traveling is passed through a low pass filter ( = LPF (ΔNi)), the rotational speed difference ΔNi before passing through the low-pass filter as shown in the following equation.
A means for canceling the above and obtaining the corrected rotational speed difference ΔNf can be considered.

ΔNf = ΔNi-LPF (ΔNi)

However, according to this means, for example, when slips occur continuously between the front and rear wheels 14 and 15 on a slippery road surface, the rotational speed difference due to the slips is canceled.

On the other hand, in the wheel driving force distribution control system 90 of the present embodiment, when the traveling conditions (1) to (4) are satisfied, the contents of the unique data storage means are updated to satisfy the traveling conditions (1) to (3). Slip is unlikely to occur when driving is possible. Therefore, in this embodiment, the rotational speed difference between the front and rear wheels 14 and 15 detected when the front and rear wheels 14 and 15 are unlikely to slip can be updated as the inherent rotational speed difference due to the outer diameter difference. As a result, it is possible to prevent the rotation speed difference from being canceled due to slip, and it is possible to perform stable traveling.

<Other Embodiments> The present invention is not limited to the above-described embodiments. For example, the embodiments described below are also included in the technical scope of the present invention.
The present invention can be implemented by making various changes other than the following without departing from the scope of the invention. (1) In the above-described embodiment, the traveling conditions for updating the specific rotational speed difference ΔNm and the vehicle speed Vm stored in the EEPROM 73 are the four conditions (1) to (4) described above, but the traveling conditions are such that slip does not easily occur. For example, the number and contents of the traveling conditions are not limited to the above items.

(2) In the above embodiment, the unique data storage means (EEPROM 73) stores the unique rotation speed difference ΔNm and the vehicle speed Vm. However, ΔNm / Vm may be stored or may be predetermined. As long as the data is updated when the vehicle travels steadily at the fixed vehicle speed, only the unique rotation speed difference ΔNm may be updated and stored in the unique data storage means.

(3) In the above embodiment, the vehicle speed V is calculated as the average value of the rotational speeds of the rear wheels 15, 15, but the method of calculating the vehicle speed is not limited to this. Therefore,
For example, the rotation speed of any one of the front and rear four wheels may be the vehicle speed.

(4) Also, the difference between the front and rear rotational speeds is not limited to the above-described embodiment. For example, the difference between the rotational speed of one front wheel and the rotational speed of one rear wheel is the front and rear wheels. The rotational speed difference may be calculated.

(5) In the above embodiment, the front wheels 14 are the "always driving wheels" according to the present invention, and the rear wheels 15 are the "wheels other than the always driving wheels" according to the present invention. May be.

(6) In the above-described embodiment, each time the steady state is entered, the characteristic rotational speed difference Δ stored in the EEPROM 73 is stored.
Although Nm and the vehicle speed Vm are updated, the contents stored in the EEPROM (unique data storage means) may be updated only when the values of Vm and ΔNm change. Further, when the engine is started (when the ignition is turned on), the values of Vm and ΔNm are read from the EEPROM to the RAM as initial values, and the values stored in the RAM are used until the engine is stopped thereafter, and when the engine is stopped. RAM to EEPROM (when ignition is off)
It may be stored in. By doing so, the frequency of writing to the EEPROM can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a drive system of an automobile according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing the basic configuration of the torque transmission device.

FIG. 3 is a sectional view of a V-shaped recess.

FIG. 4 is a block diagram showing a configuration of an ECU.

FIG. 5: Flow chart of the main program

FIG. 6 is a flowchart of a unique data update process.

[Explanation of symbols]

14 ... Front wheels (continuously driven wheels) 15 ... rear wheels (wheels other than constantly driven wheels) 30 ... Torque transmission device (torque transmission means) 31 ... Input section 32 ... Output unit 61 ... Rotation speed sensor 73 ... EEPROM (unique data storage means) 90 ... Wheel driving force distribution control system

Claims (3)

[Claims] 1. An output unit that has an input unit that rotates in conjunction with a constantly driven wheel among front and rear wheels of an automobile, and an output unit that rotates in conjunction with a wheel other than the constantly driven wheel, and that outputs from the input unit. Torque transmission means capable of changing the transmission torque to the section, and taking in the respective rotation speeds of the front and rear wheels detected by a sensor provided in the vehicle, and a predetermined rotation difference according to the rotation speed difference between the front and rear wheels. The relationship between the transmission torque control means for controlling the transmission torque of the torque transmission means based on the torque command value, the vehicle speed, and the inherent rotational speed difference generated between the front and rear wheels due to the outer diameter difference between the front and rear wheels is stored. Based on the vehicle speed that can be calculated from the rotational speed when the vehicle travels under predetermined traveling conditions, and the inherent rotational speed difference that is obtained as the rotational speed difference between the front and rear wheels. And a unique data update means for updating the stored content of the unique data storage means, wherein the transmission torque control means is based on the traveling vehicle speed and the stored content of the unique data storage means. Wheel driving force characterized in that the rotation speed torque command value is determined based on a value obtained by canceling the rotation speed difference between the front and rear wheels that is running, by determining the rotation speed difference with respect to the vehicle speed. Distribution control system. 2. The vehicle speed when traveling under the predetermined traveling condition is Vm, the characteristic rotational speed difference when traveling under the predetermined traveling condition is ΔNm, the vehicle speed during traveling is Vi, and The rotation speed difference during traveling is ΔNi, and the inherent rotation speed difference with respect to the traveling vehicle speed Vi is Δ.
In the case of Nh, Vm and ΔNm, or
The ΔNm / Vm is stored, and the rotation difference torque command value is determined based on ΔNf obtained from ΔNh = Vi · ΔNm / Vm ΔNf = ΔNi−ΔNh. Wheel driving force distribution control system. 3. The predetermined traveling condition is that the throttle opening of the vehicle is a predetermined value or less, the amount of change in the rotational speed difference between the front and rear wheels is a certain value or less, and the amount of change in the vehicle speed is constant. The vehicle speed is equal to or less than a value and the vehicle speed is equal to or more than a predetermined value.
Alternatively, the wheel driving force distribution control system according to item 2.