JPH11278080A - Control device of torque distribution clutch for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a torque distribution clutch for a vehicle to provide transmission torque in a size to correspond with a command value to the torque distribution clutch regardless of slippage of relation between the command value and actual transmission torque due to a mechanical or electrical primary factor. SOLUTION: It is possible to provide transmission torque tr in size corresponding to a command value tref for an electromagnetic clutch 30 regardless of slippage of relation between the command value tref actual transmission torque tr due to a mechanical or electric primary factor as a correction value Δtref is computed in accordance with a rotational speed difference ΔNav of the electromagnetic clutch 30 and input torque tinav of the electromagnetic clutch 30 in a command value correction means 128. Shortage torque Δtref which is a difference between the command value (command torque) tref found from an equation of motion of a driving system rotor in a motive power transmission route of a vehicle and the actual transmission torque tr is a function of input torque tin of the electromagnetic clutch 30 and a rotational speed difference ΔN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle torque distribution clutch having a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to a plurality of wheels.

[0002]

2. Description of the Related Art Each wheel is provided with a torque distribution clutch provided in series on a power transmission path from a prime mover to a plurality of wheels, or provided in parallel with a differential gear device on the power transmission path. 2. Description of the Related Art There is known a vehicle in which a rate of torque transmitted to a vehicle is adjusted. For example, a four-wheel drive vehicle having a torque distribution clutch provided in series between the engine and the front wheel differential gear device or the rear wheel differential gear device, and provided in parallel with a central differential gear device (center differential) For example, a four-wheel drive vehicle having a differential limiting clutch. The above torque distribution clutch usually obtains traction according to the vehicle state at the time of starting,
It is used for torque distribution control for the purpose of obtaining driving force of wheels according to the weight distribution of the vehicle. For example, a driving force distribution control device for a vehicle described in Japanese Patent Application Laid-Open No. 2-39333 is one example.

In the above-described conventional vehicle driving force distribution control device, in order to eliminate the difference between the target transmission torque of the hydraulic clutch and the actual transmission torque, the target transmission is determined based on the rotational speed difference between the front and rear wheels or the left and right wheels. A technique of providing a target transmission torque correction unit for obtaining a torque correction value is disclosed. According to this, when the clutch engagement force is applied so as to obtain the target transmission torque, the target transmission torque correction value is determined by the rotation speed difference so as to eliminate the transmission torque difference generated between the target transmission torque and the actual transmission torque. Is obtained, and a command value corrected by the target transmission torque correction value, that is, a control signal is output.

That is, the hydraulic clutch used in such a conventional vehicle driving force distribution control device generally has a transmission torque corresponding to a command value to the rotation speed difference, that is, a working hydraulic pressure supplied thereto, regardless of the rotational speed difference. A clutch with a characteristic that has a clutch characteristic in which the transmission torque gradually increases with an increase in the rotational speed difference even when the operating oil pressure supplied to it is constant because the clutch judder phenomenon occurs. Therefore, based on the relationship stored in advance, a correction value for correcting the relationship that the transmission torque increases with the increase in the rotational speed difference is obtained based on the rotational speed difference, thereby obtaining the correction value for the hydraulic clutch. The command value and the actual transmission torque of the hydraulic clutch are made to match.

[0005]

As the torque distribution clutch, there are used a hydraulic clutch operated via hydraulic pressure as described above and an electromagnetic clutch operated using the magnetic force of an electromagnetic solenoid. Due to mechanical factors such as individual differences in friction characteristics and changes over time (deterioration) in friction characteristics, or electrical factors such as reduced accuracy of the drive current detection device, the command value for the torque distribution clutch and the actual transmission torque And the relationship may be shifted. However, in the above-described conventional driving force distribution control device, the transmission torque corresponding to the command value cannot be obtained in the driving force distribution control. There was a disadvantage that the characteristics were affected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object the purpose of irrespective of the deviation of the relationship between the command value due to mechanical or electrical factors and the actual transmission torque. It is an object of the present invention to provide a control device for a vehicle torque distribution clutch capable of obtaining a transmission torque having a magnitude corresponding to a command value for the distribution clutch.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the gist of the present invention is to provide a torque distribution clutch for adjusting a ratio of torque transmitted from a prime mover to a plurality of wheels, respectively. A control device for a vehicle torque distribution clutch that outputs a command value for setting a transmission torque of the torque distribution clutch to a predetermined value, comprising: (a) input torque calculation means for calculating an input torque of the torque distribution clutch; (B) based on the input torque of the torque distribution clutch calculated by the input torque calculation means,
Command value correcting means for correcting the command value.

[0008]

According to this structure, the command value correction means corrects the command value for the torque distribution clutch based on the input torque of the torque distribution clutch. Regardless of the deviation of the relationship between the torque and the actual transmission torque, a transmission torque having a magnitude corresponding to the command value for the torque distribution clutch can be obtained. This is because the insufficient torque, which is the difference between the command value (command torque) obtained from the equation of motion of the drive system rotating body in the power transmission path of the vehicle and the actual transmission torque, is a function of the input torque of the torque distribution clutch. .

[0009]

According to a second aspect of the present invention, an input-side rotating member and an output-side rotating member of the torque distribution clutch are provided. A rotation speed difference calculation unit that calculates a rotation speed difference with the member is further included, and the command value correction unit includes:
The command value is corrected based on the rotation speed difference of the torque distribution clutch calculated by the rotation speed difference calculation unit and the input torque of the torque distribution clutch calculated by the input torque calculation unit. .

[0010]

In this way, the command value is corrected based on the difference between the rotational speed of the torque distribution clutch and the input torque, so that the command value due to mechanical or electrical factors and the actual transmission torque are corrected. Irrespective of the deviation of the relationship, the transmission torque having a magnitude corresponding to the command value for the torque distribution clutch can be obtained more accurately. The insufficient torque, which is the difference between the command value (command torque) obtained from the equation of motion of the drive system rotating body in the power transmission path of the vehicle and the actual transmission torque, is a function of the rotational speed difference of the torque distribution clutch and the input torque. Because there is.

[0011]

According to a third aspect of the present invention, there is provided a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to a plurality of wheels. A control device for a vehicle torque distribution clutch that outputs a command value for setting a transmission torque of the torque distribution clutch to a predetermined value,
(a) a rotation speed difference calculation means for calculating a rotation speed difference between the input side rotation member and the output side rotation member of the torque distribution clutch, and (b) the torque distribution clutch calculated by the rotation speed difference calculation means. Command value correcting means for correcting the command value based on the rotational speed difference.

[0012]

According to the third aspect of the present invention, the command value correction means corrects the command value for the torque distribution clutch based on the rotational speed difference of the torque distribution clutch. Regardless of the deviation of the relationship between the value and the actual transmission torque, a transmission torque of a magnitude corresponding to the command value for the torque distribution clutch is obtained. The shortage torque, which is the difference between the command value (command torque) obtained from the equation of motion of the drive system rotating body in the power transmission path of the vehicle and the actual transmission torque, is a function of the rotation speed difference of the torque distribution clutch. is there.

[0013]

A fourth aspect of the present invention to achieve the above object is to provide a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to a plurality of wheels. A control device for a vehicle torque distribution clutch that outputs a command value for setting a transmission torque of the torque distribution clutch to a predetermined value,
(a) first command value output means for outputting a first command value in a first section; and (b) outputting a second command value different from the first command value in a second section different from the first section. And (c) the first section and the second section.
Command value correcting means for correcting the command value based on the input / output rotation speed of the torque distribution clutch in the section and the command values in the first section and the second section thereof.

[0014]

According to this configuration, the command value is corrected by the command value correction means based on the command value and the input / output rotation speed in the first section and the second section. Alternatively, even if a deviation occurs in the relationship between the command value and the actual transmission torque due to electrical factors, a transmission torque of a magnitude corresponding to the command value for the torque distribution clutch can be obtained. That is, the command value difference (command torque difference) and the slip ratio difference with respect to the torque distribution clutch during actual running change in relation to the clutch characteristics between the command value of the actual torque distribution clutch and the actual transmission torque. Therefore, the command value is corrected so that the operation area indicated by the command value difference and the slip rate difference corresponding to the command value falls within the normal operation area set in advance, so that the command value and the actual transmission The transmission torque due to the deviation of the relationship with the torque is corrected to correspond to the command value.

[0015]

A fifth aspect of the present invention to achieve the above object is to provide a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to a plurality of wheels. A control device for a vehicle torque distribution clutch that outputs a command value for setting a transmission torque of the torque distribution clutch to a predetermined value,
(a) the input torque of the torque distribution clutch, the rotation speed difference between the input side rotation member and the output side rotation member of the torque distribution clutch, the command value difference for the torque distribution clutch in the first and second predetermined sections; It is intended to include torque distribution clutch abnormality determining means for performing abnormality determination of the torque distribution clutch based on any of the slip ratio differences of the torque distribution clutch.

[0016]

According to the fifth aspect of the invention, in the torque distribution clutch abnormality determining means, the input torque of the torque distribution clutch, the rotational speed difference between the input side rotation member and the output side rotation member of the torque distribution clutch, Is determined based on one of the command value difference for the torque distribution clutch and the slip ratio difference for the torque distribution clutch in the first section and the second section. It can be easily recognized that a difference occurs between the command value and the actual transmission torque due to a factor. Therefore, you can correct the misalignment,
Alternatively, by correcting the command value, a transmission torque having a magnitude corresponding to the command value for the torque distribution clutch can be obtained.

[0017]

In another preferred embodiment, the vehicle is a four-wheel drive vehicle, and the torque distribution clutch includes an engine and a front wheel differential gear device for adjusting torque distribution between front and rear wheels of the vehicle. Alternatively, it has a torque distribution clutch provided in series with the rear wheel differential gear device, or a differential limiting clutch provided in parallel with the central differential gear device (center differential).

Preferably, the vehicle further includes at least steady-state running determining means for determining steady-state running of the vehicle which requires at least straight running of the vehicle. Is determined, the input torque of the torque distribution clutch is calculated. In this case, there is an advantage that the command value correcting means corrects the command value based on the input torque of the torque distribution clutch when the steady running of the vehicle is determined.

[0019] Preferably, the vehicle further includes a steady-state running determining means for determining a steady-state running of the vehicle which requires at least a straight running of the vehicle. When the traveling is determined, a rotation speed difference between the input side rotation member and the output side rotation member of the torque distribution clutch is calculated. According to this configuration, the command value correction unit sets the command value based on a rotation speed difference between the input-side rotating member and the output-side rotating member of the torque distribution clutch when steady running of the vehicle is determined. There is the advantage of correcting.

Preferably, the vehicle further includes a steady-state running determining means for determining at least a steady running of the vehicle which requires a straight running of the vehicle, and the input torque calculating means includes a steady-state running of the vehicle by the steady running determining means. Is determined, the input torque of the torque distribution clutch is calculated, and the rotational speed difference calculation means is configured to determine the torque distribution clutch when the steady travel of the vehicle is determined by the steady travel determination means. The rotation speed difference between the input side rotation member and the output side rotation member is calculated. With this configuration, the command value correction unit performs the control based on the input torque of the torque distribution clutch and the rotation speed difference between the input-side rotating member and the output-side rotating member when the steady running of the vehicle is determined. There is an advantage of correcting the command value.

Preferably, the input torque calculating means changes the input torque of the torque distribution clutch when a steady running of the vehicle is determined by the steady running determining means within a predetermined section. It is calculated as an average value. Further, the rotation speed difference calculation means sets a rotation speed difference between the input rotation member and the output rotation member of the torque distribution clutch when the steady running of the vehicle is determined by the steady running determination means. It is calculated as an average value within the determined predetermined section. In this way, the influence of noise due to rotation fluctuation of a rotating member such as a propeller shaft or vehicle body vibration is reduced, and a reliable input torque of the torque distribution clutch, an input-side rotating member and an output-side rotating There is an advantage that a rotational speed difference with the member can be obtained.

Preferably, the steady-state running determining means includes an input torque (output torque of the engine) of the torque distribution clutch, a command value for the torque distribution clutch, and a torque distribution of the torque distribution clutch when the vehicle is traveling straight. When the difference in rotation speed between the input-side rotating member and the output-side rotating member of the clutch and the vehicle speed are smaller than predetermined values, the vehicle is determined to be in a steady running state.
In this way, the influence of noise caused by rotation fluctuations of a rotating member such as a propeller shaft is reduced, and a reliable input torque of the torque distribution clutch and a reliable connection between the input-side rotating member and the output-side rotating member are reduced. There is an advantage that a rotation speed difference can be obtained.

Preferably, the command value correcting means includes:
The correction value is calculated based on at least one of the input torque of the torque distribution clutch and the rotational speed difference between the input-side rotating member and the output-side rotating member from a previously stored correction value calculation formula or a previously stored map. Then, the command value is corrected based on the correction value.

Preferably, the rotational speed difference between the input-side rotating member and the output-side rotating member of the torque distribution clutch calculated by the rotational speed difference calculating means is calculated as a wheel diameter difference between a front wheel and a rear wheel of the vehicle. And a rotational speed difference correcting means for correcting based on the rotational speed. With this configuration, the error based on the wheel diameter difference is removed from the rotation speed difference between the input side rotation member and the output side rotation member of the torque distribution clutch calculated by the rotation speed difference calculation unit. There is an advantage that the reliability of the rotational speed difference can be further enhanced.

Preferably, the rotational speed difference correcting means is configured to rotate the input-side rotating member and the output-side rotating member of the torque distribution clutch when the torque distribution clutch is released during straight running of the vehicle. A wheel diameter correction coefficient is calculated from the speed difference, and the rotation speed around the shaft of the torque distribution clutch calculated based on the vehicle speed and the rotation speed derived from the diameter difference generated from the wheel diameter difference based on the wheel diameter correction coefficient. The difference is calculated, and the rotation speed difference derived from the diameter difference is corrected by subtracting the difference from the rotation speed difference calculated by the rotation speed difference calculation means.

Preferably, the first command value output means outputs a first command value for releasing the torque distribution clutch in a first section, and the second command value output means outputs the torque value. A second command value for causing the distribution clutch to be in a semi-engaged state allowing relative rotation of the input-side rotator and the output-side rotator is output in the second section. In this case, the correction by the command value correcting means is simplified, and the reliability is improved.

Preferably, the first section and the second section
A slip ratio difference calculating means for calculating a slip ratio difference between the front and rear wheels based on the input / output rotation speed difference and the vehicle speed of the torque distribution clutch in the section, and a slip ratio difference between the front and rear wheels in the first and second sections. A slip ratio difference variable calculating means for calculating a variable dslip corresponding to the change amount of the slip ratio difference between the front and rear wheels; a first command value and a second command value in the first section and the second section; And a command value difference corresponding variable calculating means for calculating a variable atr which changes in accordance with the command value difference based on the input torque of the variable.
The command value is corrected based on dslip and atr. In this case, the deviation of the transmission torque characteristic of the torque distribution clutch is properly corrected.

Preferably, the torque distribution clutch abnormality determining means calculates an input torque of the torque distribution clutch based on a rotational speed difference between an input side rotation member and an output side rotation member of the torque distribution clutch. The abnormality of the torque distribution clutch is determined on the basis of exceeding the abnormality determination reference value.

[0029] Preferably, the torque distribution clutch abnormality determining means includes a command value in the first section and the second section in two-dimensional coordinates consisting of an axis representing a command value difference and an axis representing a slip ratio difference. The abnormality of the torque distribution clutch is determined based on the fact that the position indicating the difference and the slip ratio difference deviates from a predetermined determination reference region.

[0030]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a vehicle power transmission device provided with a control device according to one embodiment of the present invention. In the figure, a transaxle housing 18 accommodating an automatic transmission 12 with a torque converter, a front differential gear device 14, and a transfer 16 is fastened to an engine 10 functioning as a prime mover. Thus, the output torque of the engine 10 is transmitted to the pair of left and right front wheels 24 and 26 via the automatic transmission 12 with a torque converter, the front differential gear device 14 and the pair of left and right axles 20 and 22. , The automatic transmission with torque converter 12, the transfer 16, the propeller shaft 28, the electromagnetic clutch 30 functioning as a torque distribution clutch, the rear differential gear device 32, and a pair of right and left rear wheels via a pair of left and right axles 34, 36. The power is transmitted to the wheels 38 and 40.

The electromagnetic clutch 30 functions as a torque distribution clutch for adjusting the ratio of the torque transmitted from the engine 10 to the front wheels 24, 26 and the rear wheels 38, 40, respectively. And an output friction plate 46 connected to and rotating with the drive pinion 44 of the rear differential gear 32, the input friction plate 42 and the output friction An electromagnetic solenoid 48 that frictionally engages with the plate 46 by pressing the plate 46 in accordance with an electromagnetic force is basically provided, and generates a transmission torque having a magnitude corresponding to a command value t _ref from an electronic control device 110 described later. It is configured as follows. When the electromagnetic clutch 30 is released, 100% of the torque output from the engine 10 is transmitted to the front wheels 24 and 26, but when the electromagnetic clutch 30 is completely engaged, the output from the engine 10 is output. 50% of the applied torque is transmitted to the front wheels 24 and 26,
Since the remaining 50% is transmitted to the rear wheels 38 and 40, in the present embodiment, the torque distribution adjustment range of the electromagnetic clutch 30 is such that the weight distribution ratio between the front wheels and the rear wheels is 0.5: 0.5. In some cases, the torque distribution ratio ranges from 1: 0 to 0.5: 0.5. Generally, when the electromagnetic clutch 30 is completely engaged, the torque of the front and rear wheels is distributed corresponding to the weight distribution of the front and rear wheels. In this embodiment,
The torque of the front and rear wheels can be adjusted from the front wheel drive state to the directly connected 4WD by the electromagnetic clutch 30.

As shown in detail in FIG.
Reference numeral 0 denotes an input shaft 58 having a universal joint 50 and a clutch drum 52 connected to the propeller shaft 28 at both shaft ends and rotatably supported by a clutch housing 54 via bearings 56;
The output shaft 62 is rotatably supported by the clutch housing 54 via a bearing 60 in a state of being concentric with the output shaft 8, and the input shaft 58 is rotatably fitted to the shaft end face of the input shaft 58. And an electromagnetic solenoid 48 supported on an input shaft 58 via a bearing 66 while being engaged with a projection 65 of a clutch housing 54 which is a non-rotatable member so that the clutch rotor 64 cannot rotate. An annular magnetic member 68 that is attracted by the magnetic force of the electromagnetic solenoid 48 and is provided between the inner peripheral surface of the clutch drum 52 and the outer peripheral surface of the clutch rotor 64;
Control (pilot) in which a relatively small friction torque is generated by the magnetic force of the electromagnetic solenoid 48
It has a clutch 70, a cam ring 72 to which friction torque from the control clutch 70 is transmitted, and a ball cam 74 that contacts the cam ring 72, and transmits a relatively small rotational force transmitted through the control clutch 70 in the thrust direction. A pressing device 78 that converts the force into a force (in the axial direction) and transmits the force to the annular pressing member 76 while boosting the force.
The input-side friction is provided so as to be movable in the axial direction with respect to the inner peripheral surface of the clutch rotor 64 and the outer peripheral surface of the clutch rotor 64 and not to be rotatable relative to the axis, and is pressed by the thrust force from the annular pressing member 76. It has a plate 42 and an output-side friction plate 46, and generates a transmission torque of a magnitude corresponding to the drive current supplied to the electromagnetic solenoid 48, for example, according to the characteristics shown in FIG.

Returning to FIG. 1, the vehicle has a four-wheel drive mode.
Four-wheel drive selection switch 8 operated when selecting
0, a wheel speed sensor 8 for detecting the rotation speed of the left front wheel 24
2. Wheel speed sensor 8 for detecting the rotation speed of the right front wheel 26
4. Wheel speed sensor 8 for detecting the rotation speed of the left rear wheel 38
6. Wheel speed sensor 8 for detecting the rotation speed of the right rear wheel 40
8. The longitudinal G of the vehicle, that is, the acceleration G in the traveling direction_XDetect
Front and rear G sensor 90, the left and right G of the vehicle,
Acceleration G_YRight and left G sensor 92 for detecting steering, steering
Rudder for detecting the steering angle of the vehicle operated by the wheel 93
Angle sensor 94, a slot operated by an accelerator pedal
Throttle sensor 96 for detecting tor opening, engine 1
An engine rotation speed sensor 98 for detecting a rotation speed of 0;
Check the actual gear position of the automatic transmission 12, that is, the shift position.
Outgoing shift position sensor 100, brake pedal 102
Brake sensor 104, which detects that the
Detecting operation of working brake lever 106
PB brake sensors 108 are provided, respectively.
From these switches or sensors.
S4WD indicating that the mode is selected, the left front wheel 24
Rotation speed N_FLSignal SN indicating_FL, The rotation speed of the right front wheel 26
Degree N_FRSignal SN indicating_FR, The rotation speed N of the left rear wheel 38_RLTo
Signal SN shown_RL, The rotation speed N of the right rear wheel 40_RRSignal indicating
SN_RR, Longitudinal acceleration G_XSignal SG indicating_X, Lateral acceleration
G_YSignal SG indicating_Y, A signal Sδ indicating the steering angle δ of the vehicle,
Throttle opening θ_thSθ indicating the number of rotations of the engine 10
Rolling speed N _ESignal SN indicating_E, A signal indicating the shift position SP
No. SSP, signal SB indicating operation of the brake pedal 102
K, a signal indicating the operation of the parking brake lever 106
SPB supplies the electronic control device 110 for torque distribution control.
Be paid.

The electronic control unit 110 includes a CPU, RA
M, a ROM, a so-called microcomputer including an input / output interface, etc., wherein the CPU processes the above input signal by executing a program stored in the ROM in advance while utilizing the storage function of the RAM, and the Output a control signal to the electromagnetic clutch 3
An operation indicator light 112 indicating that the electromagnetic clutch 30 is operating and an operation indicator light 112 indicating that the electromagnetic clutch 30 is abnormal are displayed. FIG.
Shows a configuration example of the electronic control device 110 in detail. Electronic control unit 1 for engine control and shift control
15, the signal indicating the throttle opening θ _th , the gear position of the automatic transmission 12, the engine system failure, and the engine 10
Is supplied to the electronic control unit 110. Electronic control unit 110
Are the ABS control device 116 and the 4WD control device 1
17 and a drive circuit 118 that outputs a control current to the electromagnetic clutch 30 according to a command signal representing a command value t _ref .

FIG. 5 is a functional block diagram for explaining main control functions of the electronic control unit 110. As shown in FIG. In FIG. 5, torque distribution control means 120 includes a plurality of control modes for controlling the torque distribution of the front wheels and the rear wheels of the vehicle, such as control during starting, control during turning, control during normal running, and control during braking. Is selectively selected based on the vehicle state, and the transmission torque of the electromagnetic clutch 30 or the drive current to be supplied to the electromagnetic clutch 30 is determined in accordance with a control formula preset in the selected control mode. Control signal SC representing command value t _ref of corresponding magnitude
Is output and the operation indicator lamp 112 is turned on. For example, when the four-wheel drive mode is selected by the four-wheel drive selection switch 80 and the brake sensor 104 detects the operation of the main brake, the control during braking is selected. Also, for example, based on the traveling state indicated by the vehicle speed V and the vehicle steering angle δ from the relationship shown in FIG. 6, start-up control (FIG. 6), turning traveling control (FIG. 6), and normal traveling control (FIG. 6). 6) is selected.

In the starting control, in order to obtain the maximum traction according to the state of the vehicle, the electromagnetic clutch 30 is controlled so that the torque distribution is equivalent to the weight distribution of the vehicle to the front wheels 24, 26 and the rear wheels 38, 40. Or the electromagnetic clutch 30 is controlled so as to limit the transmission torque to the rear wheels 38 and 40 according to the steering angle δ. Further, in the turning traveling control, for example, in order to enhance the steering stability during turning traveling on a snowy road or a frozen road having a small road surface friction coefficient, for example, a target yaw rate (center of gravity) serving as a neutral steer between the understeer and the oversteer. The electromagnetic clutch 30 is controlled such that the actual yaw rate follows the angular velocity around a vertical line passing through the vertical axis. Further, in the above-described normal running control, the transmission torque is increased when a difference in rotation speed between the input side and the output side of the electromagnetic clutch 30 occurs so that the torque distribution basically corresponds to the weight distribution. When four-wheel drive is not required, such as when traveling straight, the electromagnetic clutch 30 is controlled so as to reduce the engagement force as much as possible in order to increase fuel efficiency. Further, in the braking control, when the brake pedal 102 is operated, the engagement force of the electromagnetic clutch 30 is directly reduced to avoid control interference with the ABS control or the VSC control. Until the control is started, the electromagnetic clutch 30 is engaged to distribute the engine braking force to the four wheels. However, the engagement force is reduced when the ABS control is started, and released when the VSC control is started. To
The electromagnetic clutch 30 is controlled.

The input torque calculating means 122 includes the engine 1
0, the output torque (drive torque of the vehicle) around the propeller shaft 28, that is, the input torque t of the electromagnetic clutch 30.
_in (N · m) is sequentially calculated based on the actual engine speed _NE (rpm) and the throttle opening θ _th (%) or the intake air amount Q, for example, from the relationship stored in advance shown in FIG. The input torque calculating means 122 preferably has a predetermined time width and moves within a moving section which is moved with time in a state where steady running of the vehicle is determined by a steady running determining means 126 described later. the average value or moving average value of the obtained plurality of input torque t _in calculating the input torque t _iNAV. Here, the input torque t _in the rear wheel 38, 40 from the torque t _f and the electromagnetic clutch 30 to be distributed to the front wheels 24 and 26 side
The sum of the torque t _r to be distributed to the side _{(t in = t f + t} r)
Is defined as Torque t _r which is distributed to the rear wheel 38 and 40 side is the transmission torque of the electromagnetic clutch 30, in the steady state corresponds to the command value t _ref to the electromagnetic clutch 30.

The rotational speed difference calculation means 124, the rotational speed N _f speed wheel rotation N _FL of the input shaft 58 of the electromagnetic clutch 30
And the average value of N _FR and the gear ratio of the front differential gear unit 14, and the rotational speed N _r of the output shaft 62 of the electromagnetic clutch 30 is calculated as the average of the rear wheel rotational speeds N _RL and N _RR . by calculated based on the values and the rear differential gear ratio of the gear unit 32, subtracting the rotational speed N _r of the output shaft 62 from the rotational speed N _f of the input shaft 58, the input shaft 58 output shaft 6
Then, the rotational speed difference ΔN (rpm) with respect to 2, ie, the differential (slip) rotational speed ΔN (= N _f −N _r ) of the electromagnetic clutch 30 is calculated. This rotation speed difference calculating means 124 also preferably has a predetermined time width and is moved with time in a moving section in a state where steady running of the vehicle is determined by a steady running determining means 126 described later. The differential rotation speed ΔN _av is calculated as an average value of the plurality of differential rotation speeds ΔN obtained in step (1), that is, a moving average value.

The steady-state running determining means 126 determines whether or not the vehicle is running straight, based on the steering angle δ of the vehicle, and the input torque t _in of the electromagnetic clutch 30.
A command value represented by a control signal SC for the electromagnetic clutch 30, a rotational speed difference ΔN of the electromagnetic clutch 30,
And stable running determination means for determining whether or not the variation range of the vehicle speed V is smaller than a predetermined reference value, that is, the variation range. The vehicle is determined to be traveling straight, and the input torque t _in The steady traveling state of the vehicle is determined based on the command value for the clutch 30, the rotational speed difference ΔN of the electromagnetic clutch 30, and the stable traveling state in which the fluctuation width of the vehicle speed V is smaller than a predetermined fluctuation width. I do.

The command value correcting means 128 obtains the value in the above-mentioned steady running state from the relationship stored in advance, for example, in the state where the straight running and the stable running of the vehicle are determined by the above-mentioned steady running determining means 126. The correction value Δt based on the actual rotational speed difference ΔN of the electromagnetic clutch 30 and the input torque t _in of the electromagnetic clutch 30
By calculating _ref , for example, and calculating the correction formula shown in Expression 2, for example, the command value t by the normal driving control is calculated.
_ref, and the corrected command value t _ref is
Output to 0.

[0042]

Δt _ref = 1/2 ｛[(Rα / V) + 2K ₂ ] ΔN + (1-2K ₁ ) t _in ｝ (1)

[0043]

## EQU2 ## t _ref = t _ref + Δt _ref (2)

Here, the theoretical basis of Equation 1 will be described.
You. First, the command value t for the normal traveling control_refBecomes
Is represented by Also, the electromagnetic clutch during straight running
The equation of motion of the 30 input and output rotary drive systems is
Equation 4 is obtained. In Equation 4, I_fIs the engine
10 crankshaft, driveshaft, automatic change
Speed gear 12, propeller shaft 28, input shaft 58, etc.
The moment of inertia of the force-side rotating body is
It is converted instead. I_rIs the output shaft 62, the rear
Output-side rotating bodies such as the differential gear device 32 and the axles 34 and 36
Of moment of inertia around drive pinion 44
It was done. Also, T_fOccurs on the front wheels 24 and 26
Is converted to the propeller shaft 28
And T_rIs the torque generated in the rear wheels 38 and 40
It is converted around the drive pinion 44. So
These torques T_fAnd T_rIs the slip rate α
Assuming that it is a function of (μ), as shown in Equation 5,
Defined. In Equation 5, the coefficient R is the gear ratio and the vehicle ratio.
The slip ratio α (μ) is a function of the road surface friction coefficient.
This is a function of μ. Also, K₁Reflects weight distribution
And K _TwoIs to reflect the differential speed
Is the gain of

[0045]

[Number 3] _{t ref = K 1 t in +} K 2 ΔN ··· (3)

[0046]

[Number 4] _{t f = t in -t r =} I f · dω f / dt + T f ··· (4-1) t r = I r · dω r / dt + T r ··· (4-2)

[0047]

[Number 5] T _f = α (μ) [(Rω _f / V) -1] _{··· (5-1) T r = α} (μ) [(Rω _r / V) -1] ... ( 5-2)

By subtracting equation 4-2 from equation 4-1, the equation
Substituting 5-1 and 5-2 gives Equation 6, so assuming that it is in a steady state (differential value = 0 state), t _ref = t
By substituting Equation 3 for _r , Equation 7 is obtained. Therefore, if the inequality shown in Expression 8 is satisfied, it indicates that the actual transmission torque _tr is smaller than the command value _tref , and Expression 9
If the following inequality holds, it means that the actual transmission torque _tr is larger than the command value _tref . Therefore, when the deviation i.e. lack torque and actual transmission torque t _r and the command value t _ref and Delta] t _ref, it is from Equation 3 and the Equation 6 for Equation 1 is obtained.

[0049]

[6] _{t in -2t r = (I f} · dω f / dt -I r · dω r / dt) + Rα (μ) ΔN / V ··· (6)

[0050]

(1-2K ₁ ) t _in = [(Rα (μ) / V) + 2K ₂ ] ΔN (7)

[0051]

ΔN> (1-2K ₁ ) t _in / [(Rα (μ) / V) + 2K ₂ ] (8)

[0052]

ΔN <(1-2K ₁ ) t _in / [(Rα (μ) / V) + 2K ₂ ] (9)

FIGS. 8 and 9 are flow charts for explaining a main part of the control operation of the electronic control unit 110. FIG.
Is a control mode selection routine corresponding to the torque distribution control means 120, and FIG. 9 is a torque distribution clutch transmission torque correction routine. 8, after the vehicle speed V, the steering angle δ, the output signal of the brake sensor 104 and the like are read in S1, it is determined in S2 whether or not the brake pedal 102 is operated based on the signal from the brake sensor 104. Is done. If the determination in S2 is affirmative, the braking control is selected in S3, and this routine is terminated. However, if the determination in S2 is denied, then in S4, one of start control, turning drive control, and normal drive control is performed based on the vehicle speed V and the steering angle δ from the relationship stored in advance shown in FIG. Is determined. S
If the start control is determined in S4, the start control is selected in S5, if the turning control is determined in S4, the turning control is selected in S6, and the normal control in S4. Is determined, the normal traveling control is selected in S7.

Referring to FIG.
Step S corresponding to step 6 (hereinafter, step is omitted) S
In A1, whether or not the vehicle is in a steady running state,
The straight running of the vehicle and the input torque t_in, Command value t_ref,
Stable running with little change in rotation speed difference ΔN and vehicle speed V
Is determined by the steering angle δ and the input torque t._in, Command value t
_ref, The rotational speed difference ΔN, and the vehicle speed V.
It is. If the determination at SA1 is denied, the process proceeds to S
After variable initialization is performed in A7, this routine
Is terminated.

However, if the determination in SA1 is affirmative, it is determined in SA2 whether or not the variable i has reached a predetermined determination reference value A. The criterion value A corresponds to a moving average section for which an averaging operation is performed to reduce the influence of variation, and a value of, for example, several hundred milliseconds to several seconds is used. Since initially be negative judgment of the SA2, in the subsequent SA3, after they have been integrated with the input torque t _in and the rotation speed difference ΔN is loaded, "1" to the variable i in SA4
Is added and incremented, and SA1 and subsequent steps are executed again.

[0056] While the above steps are repeatedly executed, the contents of the variable i is a determination is reached the criterion value A SA2 is affirmative, at SA5, the moving average of the input torque t _in and the rotation speed difference ΔN Values t _inav and ΔN
_av is calculated by dividing the integrated value thus far by the moving average section A, respectively. In the present embodiment, SA3 to SA5 correspond to the input torque calculating means 122 and the rotational speed difference calculating means 124.

Next, at SA6 corresponding to the command value correcting means 128, the rotational speed difference ΔN _av of the electromagnetic clutch 30 and the electromagnetic clutch difference obtained at SA5 from the correction value calculation formula of the normal running control shown in Equation 1, for example. 30
The correction value Δt _ref is calculated on the basis of the input torque t _inav of the normal running control, and the normal running control obtained in the step (not shown) from the control formula of the normal running control shown in the formula 3, for example, by the correction formula shown in the formula 2 Command value t
_ref is corrected, and the corrected command value t _ref is output to the electromagnetic clutch 30. Then, after the variable i and the like are initialized in SA7, this routine is ended.

As described above, according to this embodiment, the command value
In the correction means 128 (SA6), the electromagnetic clutch 30
Rotation speed difference ΔN_avAnd the input torque of the electromagnetic clutch 30
Kt _inavCorrection value Δt based on_refIs calculated, so
Command value t due to mechanical or electrical factors_refAnd the actual biography
Ultimate torque t_rDespite the deviation of the relationship (Fig. 3),
Command value t for latch 30_refA transmission of a size corresponding to
Ultimate torque t_rIs obtained. In the power transmission path of the vehicle
Command value obtained from the equation of motion of the drive system rotating body (command
Torque) t_refAnd the actual transmission torque t_rIs the difference between
Foot torque Δt_{re f}Is, as shown in Equation 1, the electromagnetic
Input torque t of latch 30_inOf rotation speed difference ΔN
Because it is a number. It also occurs in straight running
Rotational speed difference ΔN of electromagnetic clutch 30_avIs used
On a road surface having a low road surface friction coefficient μ, the command value t_ref
There is an advantage that the correction can be performed.

Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIGS. 10 and 11 are a functional block diagram showing a main part of the control function of the electronic control unit 110 and a flowchart showing a main part of the control operation of the electronic control unit 110 according to another embodiment of the present invention. is there. In the above-described embodiment, from the correction value calculation formula of the control at the time of normal driving shown in Expression 1,
The correction value Δt based on the actual rotational speed difference ΔN _av of the electromagnetic clutch 30 and the input torque t _inav of the electromagnetic clutch 30
_ref is calculated, and the command value correction means 128 corrects the command value t _ref by the control during normal running by the correction formula shown in Expression 2.
However, in the present embodiment, in place of the command value correcting means 128, the actual rotational speed difference ΔN _av of the electromagnetic clutch 30 and the input torque t of the electromagnetic clutch 30 are replaced with the relationship shown in FIG. based on _inav determine a correction factor lambda, differs in that the command value correcting means 130 for correcting the command value t _ref by the correction coefficient lambda is provided, others are common. Hereinafter, the difference will be mainly described.

The relationship between the rotation speed difference ΔN _av and the input torque t _inav and the correction coefficient λ shown in FIG.
For each N _av and the input torque t _iNAV, the correction coefficient from deviation Delta] t _ref of the command value t _ref and the transmission torque t _r lambda [= (t
_ref + Δt _ref ) / t _ref ] is obtained experimentally. Command value correction means 13 of FIG.
0 determines the correction coefficient λ based on the actual rotational speed difference ΔN _av of the electromagnetic clutch 30 and the input torque t _inav of the electromagnetic clutch 30 from the relationship stored in advance shown in FIG. By multiplying the value t _ref , the corrected command value t _ref (= t _ref · λ) is output. SB6 in FIG. 11 corresponds to the command value correcting means 130, and the actual rotational speed difference ΔN of the electromagnetic clutch 30 calculated in SA5 from the relationship in FIG.
Based on _av and the input torque t of the electromagnetic clutch 30 _iNAV determine the correction factor lambda, a lambda correction factor command value t _ref
Is multiplied to obtain a corrected command value t _ref (= t
_ref.λ ) is output. According to this embodiment, in addition to obtaining the same effect as the above-described embodiment, the actual road surface friction coefficient μ
Is not affected by the estimation accuracy of the vehicle, there is an advantage that the control accuracy of the front and rear wheel torque distribution is improved.

FIG. 13 is a circuit diagram showing another embodiment of the present invention.
Functional block showing a main part of the control function of slave control device 110
14 and 15 show another embodiment of the present invention.
2 shows a main part of a control operation of the electronic control device 110 in the example.
It is a flowchart. In FIG. 13, the rotation speed
The difference correcting means 132 is provided between the front wheels 24 and 26 and the rear wheels 3 of the vehicle.
Electromagnetic clutch 30 generated due to the difference in diameter from 8, 40
Rotation speed difference ΔN (= N _f-N_rCorrection to remove)
U. For example, an electromagnetic clutch when the vehicle is running straight
30 input shaft 58 rotation speed N_fAnd the rotation speed of the output shaft 62
Degree N_rAnd the correction coefficient kik (= N_r/ N_f)
For example, the rotational speed difference is calculated using a correction formula shown in Expression 10.
Corrects rotation speed difference ΔN calculated by calculation means 124
You do it.

[0063]

ΔN = ΔN− (1-kik) N _f (10)

FIG. 14 shows a rotational speed difference caused by the diameter difference.
To determine the correction coefficient kik for correcting the
It is. In SC1 of FIG. 14, the correction coefficient determination flag is set.
F _kIs determined whether or not is set to "1".
You. If the determination of SC1 is affirmed, the correction coefficient has already been set.
This routine ends because kik is in the required state.
However, if the judgment of SC1 is denied,
Whether the vehicle is traveling straight ahead is determined based on the steering angle δ.
Is determined.

If the determination at SC2 is negative, the vehicle
Other than the difference in diameter between the front wheels 24, 26 and the rear wheels 38, 40
The factor is the correction coefficient kik (= N_r/ N_fImproper included in)
Since this is the state, this routine is terminated. But,
If the determination of SC2 is affirmed, the electromagnetic
After the clutch 30 is released, the electromagnetic
Speed N of the input shaft 58 of the switch 30_fAnd rotation of output shaft 62
Rolling speed N_rIs required, and the correction
The number kik (= N_r/ N_f) Is calculated. And SC5
A correction coefficient indicating that the correction coefficient kik has been determined.
Number determination flag F _kIs set to “1”.

[0066] In SD1 in FIG. 15, whether or not the correction standby flag F _A indicating a state capable of correction of the torque command value is set to "1" is determined. Initially, the determination of SD1 is denied, so that SD2 and subsequent steps are executed. SD2
Steps SD6 to SD6 are the same as steps SA1 to SA5 in FIG. In SD7 following SD6, the vehicle is traveling straight and in a stable traveling state, and the rotational speed difference ΔN _av of the electromagnetic clutch 30 and the input torque t of the electromagnetic clutch 30 are set.
_{Since inav} has been determined, the correction standby flag F _A
Is set to “1”. Accordingly, since the judgment of SD1 of the next control cycle is positive, the SD8, whether correction coefficient determination flag F _k which indicates that the correction coefficient kik is determined is set to "1" is determined You.
If the determination in SD8 is negative, this routine is ended in order to avoid correction of the command value _tref .

However, if the determination at SD8 is affirmative, the control goes to SD9 corresponding to the rotational speed difference correction means 132.
In, from equation 10 the correction coefficient _{kik (= N r / N f} )
The rotational speed difference ΔN _av calculated by SD6 based on the above is corrected. Then, in SA6 similar SD10 in FIG. 9, the command value t _ref is corrected based on the rotational speed difference .DELTA.N _av and the input torque t _iNAV of the corrected. Then, in SD11, the correction standby flag F _A is cleared to “0”, and after the variable i and the like are initialized in SD12, the present routine is terminated.

According to this embodiment, the same effects as those of the embodiment shown in FIGS. 5 and 10 can be obtained.
The rotational speed difference ΔN _av based on the correction coefficient kik so as not to include the displacement due to the diameter difference between the rear wheels 4 and 26 and the rear wheels 38 and 40.
Is corrected, there is an advantage that the control accuracy of the torque distribution is further enhanced.

FIGS. 16 and 17 are a functional block diagram showing a main part of the control function of the electronic control unit 110 and a flowchart showing a main part of the control operation of the electronic control unit 110 according to another embodiment of the present invention. is there. The judgment reference line L in FIG. 18 is a reference for judging a poor torque transmission of the electromagnetic clutch 30, that is, an abnormal decrease in the transmission torque due to abnormal wear of the input-side friction plate 42 and the output-side friction plate 46, disconnection of the electromagnetic solenoid 48, and the like. And the torque distribution control means 12
In the normal running control by 0, the value is determined based on the maximum value of the maximum rotational speed difference or a value obtained by adding a margin value to the input torque t _inav of the electromagnetic clutch 30. In FIG. 16, the torque distribution clutch abnormality determination means 134 determines the actual electromagnetic clutch 30 obtained by the input torque calculation means 122 and the rotation speed difference calculation means 124 from the relationship shown in FIG. based on the input torque t _iNAV and rotational speed difference .DELTA.N _av, it determines transmission torque abnormality reduction of the electromagnetic clutch 30.

In FIG. 17, SE1 to SE9 are the same as SD1 to SD9 in the embodiment of FIG. SE9
In the subsequent SE10, for example, a fail determination routine shown in FIG. 19 is executed. That is, in SF1 of FIG. 19, the actual input torque t of the electromagnetic clutch 30 calculated in SE6 from the relationship stored in advance shown in FIG.
_{Based on the inav} and the rotation speed difference ΔN _av , it is determined that the transmission torque of the electromagnetic clutch 30 is abnormally reduced. That is, it is determined whether or not the point indicating the actual input torque _tinav and the rotation speed difference ΔN _av is within the abnormal region in FIG. Although the routine when a negative determination in SF1 is terminated, if affirmative been the fail flag F _f in SF2 is set to "1", the present routine is terminated.

[0071] Then, in SE12 in FIG. 17, after such variable i is initialized, the SE13, the fail flag F _f is whether or not "1" is determined. This SE1
If the determination of No. 3 is negative, this routine is ended, but if it is affirmative, the fail process of SE14 is executed. In this fail processing, the failure indicator lamp 114 is turned on, and the fail state is stored in a predetermined storage location, and the drive current to the electromagnetic clutch 30, that is, the control value t _ref is gradually reduced and released gradually. The above SE10, SE13 and SE14 correspond to the torque distribution clutch abnormality determination means 134. According to the present embodiment, the input torque t _inav and the rotation speed difference ΔN _av
Since the abnormality determination of the electromagnetic clutch 30 is performed based on, the deviation of the relationship between the actual transmission torque t _r and the command value t _ref by mechanical or electrical source occurs easily recognize a deviation of the relationship Correction or command value t
By correcting _ref or the like, a transmission torque of a magnitude corresponding to the command value t _ref for the electromagnetic clutch 30 is obtained. Further, there is an advantage that abnormality determination of the electromagnetic clutch 30 can be performed on a road surface having a low friction coefficient μ.

FIG. 20 is a functional block diagram illustrating a control function of the electronic control device 110 according to another embodiment of the present invention, and FIG. 21 is a flowchart illustrating a control operation of the electronic control device 110. . FIG. 22 is a diagram illustrating a relationship used for determining abnormality of the electromagnetic clutch 30 and correcting torque.

The first command value output means 140 outputs a first command value t _refA representing a predetermined constant value, for example, 0 N · m (Newton meter) in a first section, for example, section A shown in the time chart of FIG. Torque distribution control means 1
20. Also, the second command value output means 142
In order to make the electromagnetic clutch 30 half-engaged in a second section, for example, a section B shown in the time chart of FIG. 23, a predetermined value, for example, 100 N · m (Newton meter) is set to a different value from the section A. The second command value t to represent
_refB is output to the torque distribution control means 120.

The slip rate difference calculation means 144 calculates the rotation speed difference ΔN _avA and the rotation speed difference ΔN _{avB of} the electromagnetic clutch 30 obtained by the rotation speed difference calculation means 124 as the average values in the sections A and B, respectively. From the average vehicle speeds V _A and V _B in the A section and the B section, the slip ratio difference ΔN _{av A} between the front and rear wheels in the A section and the B section.
/ V _A and ΔN _avB / V _B are calculated respectively. The slip ratio difference variable calculating means 146 _changes the slip ratio differences ΔN _avA / _VA and ΔN _avB / V _B between the front and rear wheels in the section A and the section B in accordance with the amount of change in the slip rate difference. defined variable (the amount of change in the front and rear wheels slip rate difference) DSLIP as _{[= (ΔN av B / V B} ) -
(ΔN _avA / V _A )] is calculated.

The command value difference corresponding variable calculating means 148
It is calculated as the average value in section A and section B, respectively.
First command value t_refAAnd the second command value t_refBAnd input torque
Kt _inAAnd t_inBCorresponding to the command value difference
Variable atr [= t_refB-T
_refA−1/2 (t_inB-T_inA)] Is calculated.

The command value correcting means 150 is provided with the variable shown in FIG.
2D consisting of axis indicating number atr and axis indicating variable dslip
In the coordinates, the above-mentioned variables atr and
The position indicating the number dslip is shifted from the preset normal region B.
If it deviates, it is located in the normal area B,
That is, the input / output rotation speed difference between the A section and the B section
ΔN_avAAnd ΔN_avBAnd command value t_refAAnd t_refBWhen
Based on the command value t _refIs corrected. For example,
The characteristic of the magnetic clutch 30 is T in FIG._BTor as shown
If it changes to the shortage side, the differential in section B
Rotation speed ΔN_{av B}Appears larger than shown in FIG.
From the above, in the two-dimensional coordinates of FIG.
And the point indicating the variable dslip indicates the normal area B and the variable atr
Axis (horizontal axis).
The command value t is set to be within the normal region B._refSupplement to increase
Although the correction is performed, the characteristic of the electromagnetic clutch 30 is changed to T in FIG.
_CIf the torque changes to the excessive torque side as shown in
Differential rotation speed ΔN in section B_avBIs shown in Figure 23
Because it appears smaller, the two-dimensional coordinates in FIG.
Points indicating the actual variables atr and dslip are normal regions
Be located between B and the axis (vertical axis) indicating the variable dslip
Command value so that the point falls within the normal region B.
t_refIs corrected.

[0077] Torque distribution clutch abnormality determination means 152
In the two-dimensional coordinates, when the positions of the actually determined variables atr and dslip are within the preset abnormality determination area D, the command value t _refA changes to the command value t _refB . Despite this, since the change in the slip ratio hardly occurs, it is determined that the electromagnetic clutch 30 is not operating, and the abnormality of the electromagnetic clutch 30 is determined. The abnormality determination area D is an area in which the value of the variable dslip is extremely small, and is set so that the variable dslip includes a zero position along the axis indicating the variable atr.

The theoretical basis for correcting the command value t _ref based on the normal region B will be described below. The equation of motion of the rotary drive system on the input and output sides of the electromagnetic clutch 30 is as shown in Equation 11. Here, similarly to Equation 4,
I _r is obtained by converting the inertia moment of the output rotary member of the electromagnetic clutch 30 around the output shaft 62, the drive pinion 44 (input shaft 58) the moment of inertia of the input-side rotary member of the electromagnetic clutch 30 is I _f about It is converted to Further, ω _f and ω _r are the rotational angular velocities of the input shaft 58 and the output shaft 62, μ (sf) and μ (sr) are the longitudinal force coefficients of the front wheels 24, 26 and the rear wheels 38, 40, W
ground load, sf and sr is the slip ratio of the front wheels 24, 26 and rear wheels 38 and 40 of the _f and W _r front wheels 24, 26 and the rear wheels 38, 40 _{[= (R f ω f -V)} / R f ω
_f, and _{= (R r ω r -V)} / R r ω r ], R _f and R _r is the dynamic load radii of the front wheels 24, 26 and rear wheels 38 and 40.

[0079]

[Number 11] _{I f · dω f / dt =} t in -t r -μ (sf) · W f · R f ··· (11-1) I r · dω r / dt = t r -μ (sr ) ・ W _r・ R _r・ ・ ・ (11-2)

In the above equation (11), dω
_f / dt = 0, so it can be regarded as dω _r / dt = 0, the equation 12. As shown in FIG. 24, the front-rear force coefficient of the front wheels 24, 26 or the rear wheels 38, 40 (the coefficient corresponding to the driving force generated on the wheels) is within the range H in which the slip ratio of the wheels is relatively small. Since it is linear with respect to the wheel slip ratio s, the front wheel 2
While proportional to the slip ratio sr slip ratio sf and the rear wheels 38, 40 4, 26, the dynamic load radius R _r of the dynamic load radius R _f and rear wheels 38 and 40 of the front wheels 24 and 26 to each other at the same value R Therefore, Equation 12 is rewritten as shown in Equation 14. Generally, the slip ratio s of the wheel is
It is a function of the vehicle speed V and the wheel (tire) peripheral speed v.
v) / v × 100 (%) or (V−v) / V × 100
(%).

[0081]

[Number 12] _{t in -t r -μ (sf)} · W f · R f = 0 ··· (12-1) t r -μ (sr) · W r · R r = 0 ··· (12 -2)

[0082]

Μ (sf) = K · sf (13-1) μ (sr) = K · sr (13-2)

[0083]

[Number 14] _{t in -t r = K · sf} · W f · R f ··· (14-1) t r = K · sr · W r · R r ··· (14-2)

Here, from Equations 14-1 and 14─2, Equation 1
5, the slip ratio sr of the rear wheels 38, 40 becomes zero in the section A in which the electromagnetic clutch 30 is released, so that the above equation (14) is transformed into the equation (16). Is led. Also, the formula 15
From next equation 18 by subtracting Equation 17, when the vertical load W _f and mutually equal W the vertical load W _r of the rear wheels 38 and 40 of the front wheels 24, 26 as shown in Equation 19.

[0085]

[Number 15] _{t in -2t r = K (sf} · W f -sr · W r) R f ··· (15)

[0086]

[Number 16] _{t inA = K · sf A ·} W f · R ··· (16-1) sr A = 0 ··· (16-2)

[0087]

## _EQU17 ## t _inA = K ・ (sf _A （W _f -sr _A・ W _r ) R (17)

[0088]

[Number 18] t _r = 1/2 · _{[t in -t inA + K · (} sf · W f -sr · W r) R -K · (sf A · W f -sr A · W r) R ] ·・ ・ (18)

[0089]

Equation 19] _{t r = 1/2 · {} t in -t inA + K · W · R [(sf-sr) - (sf A -sr A) ]} (19)

The slip ratio s of the front wheels 24, 26
f and the slip ratio sr of the rear wheels 38 and 40 are expressed as shown in Expression 20 from the definition of the slip ratio. Formula 20
It is of R · ω _f corresponds to the tire circumferential speed v. The right side is an approximation. Therefore, since (sf-sr) on the right side of Expression 19 is expressed as Expression 21, the Expression 19 can be modified as Expression 22. Using this equation 22, the wheel slip ratio sf,
Since it is not necessary to determine the sr, it can be calculated relatively accurately the actual transmission torque t _r.

[0091]

Sf = (R · ω _f −V) / Rω _f = (R · ω _f −V) / V (20-1) sr = (R · ω _r −V) / Rω _r = (R · ω _r −V) / V (20-2)

[0092]

Sf−sr = R · (ω _f −ω _r ) / V = R · ΔN / V (21-1) sf _A −sr _A = R · (ω _fA −ω _rA ) / V _A = R · ΔN _A / V _A (21-2)

[0093]

T _r = １ ／ · [t _in -t in _A + K · W · R · R (ΔN / V−ΔN _A / V _A )] (22)

However, actually, the road surface friction coefficient μ
Since it is difficult to accurately determine the longitudinal force coefficient (FIG. 24) corresponding to, the average value ΔN _avA of the rotational speed difference obtained in the section A, the input torque t _inavA , and the vehicle speed (vehicle speed) V _A And the average value ΔN of the rotational speed difference obtained in section B
_AVB, input torque _t inavB, and vehicle speed (vehicle body speed) V _B
Is used to perform the following correction. First, it is rewritten as shown in Expressions 22 to 23 above. Further, a variable at which changes in response to the command (torque) value t _ref in the A section and the B section.
r is defined as shown in Expression 24, a variable dslip that changes in accordance with the difference between the slip ratio difference (ΔN / V) between the front and rear wheels in the A section and the B section is defined as shown in Expression 25, and a constant K _{When A} is defined as shown in Expression 26, the variable atr is expressed as a linear function of the variable dslip as shown in Expression 27. In the present embodiment, an area having a predetermined width centered on the straight line indicating the relationship of the above equation 27 is set as a normal area B shown in FIG. 22, and the command value t _ref is corrected so as to fall within the normal area B. It is.

[0095]

[ _Equation 23] _travB -1/2 · (t _inavB -t _inavA ) = 1/2 · K · W · R · R (ΔN _avB / V _B -ΔN _avA / V _A ) (23)

[0096]

Atr = t _ravB −t _ravA −1/2 · (t _inavB −t _inavA ) (24)

[0097]

Dslip = (ΔN _avB / V _B −ΔN _avA / V _A ) (25)

[0098]

K _A = · K · W · R · R (26)

[0099]

Atr = K _A · dslip (27)

FIG. 21 is a flowchart for explaining a main part of the control operation of the electronic control unit 110. In the figure,
In SG1 corresponding to the first command value output means 140,
In section A, command value t _refA is output to electromagnetic clutch 30. In the following SG2, the input torque t _inavA of the electromagnetic clutch 30 and the rotation speed difference ΔN _{av A in the section A}
Is calculated. In SG3 corresponding to the second command value output means 142, the command value t _refB is output to the electromagnetic clutch 30 in section B. In the following SG4, section B
The input torque t _inavB and the rotation speed difference ΔN _avB of the electromagnetic clutch 30 within the _range are calculated. The above SG2 and SG4 correspond to the input torque calculating means 122 and the rotational speed difference calculating means 124 of FIG.

Next, the said command value difference corresponding variable calculating means 1
In SG5 corresponding to 48, the command values t _refA (t _refA = 0 in this embodiment) and t _refB, and the input torques t _inA and t in, respectively, obtained as the average values in the sections A and B by the above SG2 and SG4. based on _inB
Variable atr defined to change according to the command value difference
[= T _refB -1/2 (t _inB -t _inA )] is calculated. In SG6 corresponding to the slip rate difference calculating means 144 and the slip rate difference corresponding variable calculating means 146,
By the above SG2 and SG4, the slip ratio difference ΔN _avA / V _A and ΔN of the front and rear wheels in the A section and the B section.
_AVB / V _B are calculated, the slip ratio difference of it such as the front and rear wheels Δ
_N avA / V _A and .DELTA.N _AVB / from V _B, the variables defined dslip to vary in response to variation of the slip ratio difference of the front and rear wheels _{[= (ΔN avB / V B)} - (ΔN avA /
V _A )] is calculated.

The torque distribution clutch abnormality determining means 15
In SG7 corresponding to 2, in the two-dimensional coordinates of FIG. 22, when the positions indicating the actually obtained variables atr and dslip are within the abnormality determination area D set in advance, the command value t _refA Since the change in the slip ratio hardly occurs despite the change from the command value _trefB to the command value _trefB , it is determined that the electromagnetic clutch 30 is not operating, and the abnormality determination of the electromagnetic clutch 30 is performed. This S
If the determination in G7 is affirmative, the abnormality indicator lamp 114 is turned on in SG8 to display an abnormality.

However, if the judgment of SG7 is denied,
In SG9, the two-dimensional coordinates in FIG.
Position indicating the actually obtained variable atr and variable dslip
Is within a predetermined normal region B.
It is. If the judgment of SG9 is affirmative, the command value
This routine is ended without performing the correction.
However, in the above SG9, the variable at actually obtained at
The position indicating r and the variable dslip is the axis (horizontal) indicating the variable atr.
If it is determined that the command value has deviated to the_refTo
Actual transmission torque t_rIs in shortage,
In SG10, it is located in the normal area B.
In addition, a preset correction coefficient C is set to a command value t. _refAdd to or
Or by multiplying the command value t_refIncreases
Correction is made in the direction. Conversely, in the above SG9,
Position indicating the actually obtained variable atr and variable dslip
Is deviated to the axis (vertical axis) indicating the variable dslip
In the case, the command value t_refTo the actual transmission torque t_r
Is in an excessive state.
A preset correction coefficient C is set to
Quotation t_refCommand value by subtracting or dividing from
t_refIs corrected in the direction of decreasing. This embodiment
Then, the above SG9, SG10, SG11 are the command values.
It corresponds to the correction means 150.

As described above, according to the present embodiment, in the command value correcting means 150 (SG9, SG10, SG11), the variable atr and the slip ratio which change in accordance with the command value difference in the A section and the B section. Since the command value t _ref is corrected based on the variable dslip which changes in accordance with the difference, the electromagnetic clutch 30 is controlled regardless of the deviation of the relationship between the command value due to mechanical or electrical factors and the actual transmission torque. transmission torque t _r of magnitude corresponding to the command value t _ref is obtained. That is, the electromagnetic clutch 3 during actual traveling
0 command value difference (t _refB −0) and slip ratio difference (ΔN _avB
−ΔN _avA ) is the actual command value t of the electromagnetic clutch 30.
Since changes in relation to the clutch characteristic between the actual transmission torque t _r a _ref, working area indicated by the slip ratio difference and the corresponding the command value difference is, the normal operating range that is set in advance When the command value t _ref is corrected so as to be within B, the transmission torque _tr becomes the command value t _ref.
It is said that it corresponds to. For example, in FIG. 25, even when the characteristic curve of the electromagnetic clutch 30 is shifted to the initial characteristic curve T _A curve of insufficient torque side from T _B or torque over the curve T _C side, above the command value t _ref
It is of being returned to the vicinity of the initial characteristic curve T _A by the correction for.

Further, according to the present embodiment, the torque distribution clutch abnormality determining means 152 (SG7) uses the variable which changes in accordance with the command value difference between the section A and the section B.
Since abnormality of the electromagnetic clutch 30 based on the variable dslip which changes in accordance with the atr and the slip ratio difference is determined, the relationship between the actual transmission torque t _r and the command value t _ref by mechanical or electrical factors If a deviation occurs, it can be easily recognized, and even if the command values t _ref are corrected in steps SG9 and SG9,
G10, even SG11 if no is provided, such as by manual setting, or modify the deviation of the relationship between the clutch characteristics, or by or to correct the command value t _ref, corresponding to the command value t _ref to the electromagnetic clutch 30 The transmission torque of the following magnitude can be obtained.

Further, this embodiment has an advantage that it is possible to determine an abnormality due to a change in the characteristics of the electromagnetic clutch 30 on a road surface having a high friction coefficient μ.

FIG. 26 shows the detection or estimation of the road friction coefficient μ.
Command value t for a settable vehicle_refTo compensate for
A relationship used in place of FIG. 22 is shown. this
In FIG. 26, the low road friction coefficient μ_l, High road friction coefficient
μ_h, The road friction coefficient μ between them_mEach of
(Equation 27) atr = K_Al・ Dslip, atr = K _Ah
・ Dslip, atr = K_Am・ Normal range B around dslip
_l, B_h, B_mAre set respectively. By vehicle
Are based on the actual road friction coefficient μ.
_l, B_h, B_mOne of the selected, selected normal
Command value t based on range B_refIs corrected
You. According to the present embodiment, compared to the case of using FIG.
And the command value t_refIs further improved in accuracy.

As described above, one embodiment of the present invention has been described with reference to the drawings. However, the present invention can be applied to other embodiments.

[0109] For example, in the embodiment of FIGS. 19 described above, the command value correcting means 128 (130), the command value t _ref based on the input torque t _in and the rotation speed difference ΔN
However, the command value t is determined based on one of the input torque t _in and the rotation speed difference ΔN.
_The correction for _ref may be performed.

In the above-described embodiments shown in FIGS. 1 to 15, the command value t _ref is corrected in the normal running control for torque distribution during straight running.
The command value _tref of other torque distribution control such as start-up control and turning travel control may be corrected. For example, in order to correct the command value t _ref for another torque distribution control, a correction coefficient λ obtained by straight running may be used.

In the embodiments shown in FIGS. 13 to 15, the rotation speed difference correction means 132 for correcting the error of the rotation speed difference ΔN caused by the diameter difference between the front and rear wheels is provided.
It may be provided in other embodiments.

[0112] In the embodiment of FIGS. 19 described above, the command value correcting means 1 for correcting for the command value t _ref
28 (130) and the torque distribution clutch abnormality determining means 134 for determining abnormality of the electromagnetic clutch 30 are provided alternatively, but they may be provided simultaneously. Further, in the embodiment shown in FIGS. 20 to 25, the correction value command means 150 and the torque distribution clutch abnormality determination means 152 are provided at the same time, but they may be provided alternatively.

In the embodiment shown in FIGS.
Is the command value t only on a road surface having a small road friction coefficient μ.
_refCorrection or electromagnetic clutch 30 abnormality determination
20 to 25, the road friction coefficient is
command value t on a road surface with a large μ _refCorrection or electromagnetic
The clutch 30 was judged to be abnormal.
The means of the embodiment of the present invention may be provided on the vehicle at the same time.
No.

In the above-described embodiment, the output torque of the engine 10, that is, the input torque t _{in of the} electromagnetic clutch 30 is set.
May be used in place of the throttle opening degree θth used for calculating the throttle opening degree, the required output amount such as the accelerator pedal operation amount, the fuel injection amount of the engine 10 and the intake air amount.

In the embodiments of FIGS. 20 to 25 described above, the variable atr that changes in accordance with the difference between the command values in the section A and the section B is t _refB -1/2 (t _inB -t _inA ).
However, the difference (t _refB −0) between the A section and the B section of the command value t _ref may be the same, and the variable dslip that changes according to the slip ratio difference is [= (Δ
_N avB / V _B) - (but was _ΔN avA / V _A)], may include any other variable.

Further, the electromagnetic clutch 30 of the above-described embodiment is used.
Is provided between the propeller shaft 28 and the rear differential gear device 32. However, in order to limit the so-called center differential, a differential limiting clutch, a transfer and a front A clutch provided between the differential gear unit and a propeller shaft 28 and a pair of axles on the output side of the differential gear unit connected to the clutch. It may be a clutch or the like. In short, any torque distribution clutch of an electromagnetic type or a hydraulic type that adjusts the ratio of the torque transmitted from the prime mover to each of the plurality of wheels may be used.

Although not specifically exemplified, the present invention can be embodied with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a vehicle torque transmission control device according to an embodiment of the present invention, together with a power transmission path of a four-wheel drive vehicle.

FIG. 2 is a cross-sectional view illustrating a configuration of an electromagnetic clutch provided in a power transmission path of FIG. 1 for performing torque distribution between a front wheel and a rear wheel.

FIG. 3 is a characteristic diagram illustrating clutch characteristics of the electromagnetic clutch of FIG. 2;

FIG. 4 is a diagram illustrating a configuration example of an electronic control device of FIG. 1 in detail.

FIG. 5 is a functional block diagram illustrating a main part of a control function of the electronic control device of FIG. 1;

FIG. 6 is a diagram showing a relationship stored in advance for switching a plurality of types of control modes in the torque distribution control means of FIG. 5;

FIG. 7 is a diagram showing a relationship stored in advance for calculating an input torque in the input torque calculating means of FIG. 5;

FIG. 8 is a flowchart for explaining a main part of a control operation of the electronic control device of FIG. 4, and is a diagram showing a control mode selection routine.

9 is a flowchart for explaining a main part of a control operation of the electronic control device of FIG. 4, and is a diagram showing a torque distribution clutch transmission torque correction routine.

FIG. 10 is a functional block diagram illustrating a main part of a control function of an electronic control device according to another embodiment of the present invention,
FIG. 6 is a diagram corresponding to FIG. 5.

11 is a flowchart for explaining a main part of a control operation of the electronic control device in the embodiment of FIG. 10,
FIG. 8 is a diagram illustrating a torque distribution clutch transmission torque correction routine.

FIG. 12 is a diagram showing a relationship stored in advance for obtaining a correction coefficient λ in the embodiments of FIGS. 10 and 11;

FIG. 13 is a functional block diagram illustrating a main part of a control function of an electronic control device according to another embodiment of the present invention,
FIG. 6 is a diagram corresponding to FIG. 5.

FIG. 14 is a flowchart for explaining a main part of a control operation of the electronic control unit in the embodiment of FIG. 13,
FIG. 9 is a diagram illustrating a correction coefficient calculation routine.

FIG. 15 is a flowchart for explaining a main part of a control operation of the electronic control unit in the embodiment of FIG. 13,
FIG. 8 is a diagram illustrating a torque distribution clutch transmission torque correction routine.

FIG. 16 is a functional block diagram illustrating a main part of a control function of an electronic control unit according to another embodiment of the present invention.
FIG. 6 is a diagram corresponding to FIG. 5.

FIG. 17 is a flowchart for explaining a main part of a control operation of the electronic control unit in the embodiment of FIG. 16,
It is a figure which shows a torque distribution clutch failure processing routine.

FIG. 18 is a diagram showing a relationship stored in advance for determining an abnormality of the electromagnetic clutch in the embodiment of FIGS. 16 and 17;

19 is a flowchart for explaining a main part of a control operation of the electronic control unit in the embodiment of FIG. 16,
FIG. 8 is a diagram illustrating a fail determination routine.

FIG. 20 is a functional block diagram illustrating a main part of a control function of an electronic control device according to another embodiment of the present invention.
FIG. 6 is a diagram corresponding to FIG. 5.

FIG. 21 is a flowchart for explaining a main part of a control operation of the electronic control device in the embodiment of FIG. 20,
FIG. 8 is a diagram illustrating a torque distribution clutch transmission torque correction routine.

FIG. 22 is a diagram showing a relationship stored in advance in the embodiments of FIGS. 20 and 21 for correction of transmission torque and abnormality determination.

FIG. 23 is a time chart showing a command value t _ref and a differential rotation speed ΔN that are changed in preset sections A and B in the examples of FIGS. 20 and 21.

FIG. 24 is a diagram showing a relationship between a wheel slip ratio and a longitudinal force coefficient.

FIG. 25 is a diagram showing deviations in characteristics of the electromagnetic clutch in the embodiment shown in FIGS. 20 and 21;

FIG. 26 is a diagram showing a relationship stored in advance for correcting a transmission torque in another embodiment of the present invention, and FIG.
FIG.

[Explanation of symbols]

 10: Engine (motor) 24, 26: Front wheel (wheel) 30: Electromagnetic clutch (torque distribution clutch) 38, 40: Rear wheel (wheel) 122: Input torque calculating means 124: Rotational speed difference calculating means 128, 130, 150 : Command value correction means 134, 152: torque distribution clutch abnormality determination means 140: first command value output means 142: second command value output means 144: slip ratio difference calculation means

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Koichi Suzuki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Akihiko Ikeda 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (5)

[Claims] 1. A vehicle torque, comprising: a torque distribution clutch for adjusting a ratio of torque transmitted from a prime mover to each of a plurality of wheels, and outputting a command value for setting a transmission torque of the torque distribution clutch to a predetermined value. A control device for a distribution clutch, comprising: input torque calculation means for calculating an input torque of the torque distribution clutch; and correcting the command value based on the input torque of the torque distribution clutch calculated by the input torque calculation means. And a command value correcting means for controlling the torque distribution clutch for a vehicle. 2. The torque distribution clutch according to claim 1, further comprising a rotation speed difference calculating unit configured to calculate a rotation speed difference between an input side rotation member and an output side rotation member of the torque distribution clutch. 2. The vehicle torque according to claim 1, wherein the command value is corrected based on the calculated rotation speed difference of the torque distribution clutch and the input torque of the torque distribution clutch calculated by the input torque calculation means. Control device for distribution clutch. 3. A vehicle torque for providing a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to each of a plurality of wheels, and outputting a command value for setting a transmission torque of the torque distribution clutch to a predetermined value. A control device for a distribution clutch, comprising: a rotation speed difference calculation unit configured to calculate a rotation speed difference between an input side rotation member and an output side rotation member of the torque distribution clutch; and the torque calculated by the rotation speed difference calculation unit. And a command value correcting means for correcting the command value based on a rotational speed difference of the distribution clutch. 4. A vehicle torque for providing a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to each of a plurality of wheels, and for outputting a command value for setting a transmission torque of the torque distribution clutch to a predetermined value. A control device for a distribution clutch, comprising: first command value output means for outputting a first command value in a first section; and a second command value different from the first command value, a second command value different from the first section. Second command value output means for outputting in the section, the command value based on the input / output rotational speed of the torque distribution clutch in the first section and the second section, and the command value in the first section and the second section. And a command value correcting means for correcting the torque. 5. A vehicle torque for providing a torque distribution clutch for controlling a ratio of torque transmitted from a prime mover to each of a plurality of wheels, and outputting a command value for setting a transmission torque of the torque distribution clutch to a predetermined value. A control device for a distribution clutch, comprising: an input torque of the torque distribution clutch, a rotation speed difference between an input side rotation member and an output side rotation member of the torque distribution clutch, and the torque distribution in predetermined first and second sections. A torque distribution clutch abnormality determining means for determining abnormality of the torque distribution clutch based on one of a command value difference for the clutch and a slip ratio difference of the torque distribution clutch. Control device.