JPS62261539A - Controlling method for four-wheel drive device - Google Patents

Abstract

PURPOSE:To aim at avoidance of the occurrence of a tight braking phenomenon at the time of turning, by controlling the extent of transfer torque capacity in a center differential gear so as to cause a revolving speed differential between front and rear wheels to be kept in the value not exceeding the specified value. CONSTITUTION:In case of a 4WD vehicle, power of an internal combustion engine 1 is transmitted to a rear-wheel drive shaft 15 and a front-wheel drive shaft 17 via a 4-wheel driving transfer device and an automatic transmission 2. This 4-wheel driving transfer device 3 is provided with a center differential gear 10 which performs a differential action between front and rear wheels, and this center differential gear 10 is provided with a hydraulic-operated type differential control clutch 21 which is controlled by a hydraulic controller 22. In this case, this hydraulic controller 22 is controlled a controller 45 to control transfer torque capacity in the differential control clutch 21 so as to cause a revolving speed differential between front and rear wheels detected by each of speed sensors 46r and 46f to be kept in the value not exceeding the specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of controlling a four-wheel drive system used for intermediate wheels such as an automatic vehicle, and in particular, a method for controlling a four-wheel drive system that is used for intermediate wheels such as automatic vehicles, and particularly for a four-wheel drive system that uses a hint differential system. / Concerning the control O1l /j method.

2. Description of the Related Art As one of the four-wheel drive devices used in vehicles such as automatic vehicles, there is a center differential II device that performs differential operation between rear wheels and front wheels, and a center differential device that performs differential operation between rear wheels and front wheels. A four-wheel drive system with a limited slip differential device has already been proposed, and this type of four-wheel drive #7I
The apparatus is shown in, for example, Japanese Patent Laid-Open No. 50-147027j) and Japanese Patent Laid-Open No. 55-72420.

In the above-mentioned four-wheel drive system, the differential operation of the center differential II device avoids tight corner braking caused by the difference in turning radius between the front wheel and rear wheel when the vehicle turns. On the other hand, if any one of the 11 wheels slips and loses driving force due to driving on rough roads such as rainy roads, G4 snowy roads, muddy roads, etc., the differential operation of the center differential device All 1 by
A phenomenon occurs in which the driving force of the 11 wheels decreases, and the ability to cross the road is significantly reduced. For this reason, in a four-wheel drive device having a center differential device, a differential limiting device such as a differential control clutch is provided to limit the differential operation of the center differential device. When the difference between the rear wheel rotation speed and the front wheel rotation speed is greater than a predetermined value, that is, when the -force quiff is slipping on the road surface, the differential control clutch is engaged and the rear wheel rotation speed is It is directly connected to the front wheels, and when driving other four wheels, the differential control clutch is released to control the differential operation of the center differential device.
``A four-wheel drive system with a similar structure has already been proposed, and this is shown in Japanese Patent Application Laid-open No. 55-72420@.

Problem to be solved by the invention When the rotational speed difference between the front wheels and the rear wheels exceeds a predetermined value, the difference in center differential device! 711'1: If the use is prohibited, it will become a four-wheel drive state with direct connection to the rear wheels, and the ability to traverse rough roads will be improved by 1.
yWhen the rotational speed difference between the I wheels and the rear wheels exceeds a predetermined value and the differential operation of the center differential device is prohibited,
The difference in rotational speed between the front wheels and the rear wheels becomes less than a predetermined value, and the differential control clutch is disengaged again, causing a so-called hanging phenomenon. Therefore the actual 2,11 III
411 In order to prevent the occurrence of the hanging phenomenon.
However, when this method is used, the responsiveness deteriorates and the optimal state is not necessarily maintained in response to ever-changing vehicle driving conditions and road surface conditions.

The present invention aims to avoid the occurrence of tight corner braking phenomenon when turning, and to avoid a decrease in the driving force of one wheel when one of the plurality of wheels slips on the traveling road surface during IA on a rough road etc. The present invention aims to provide an improved control method for a four-wheel drive system that maintains the optimum conditions under ever-changing vehicle driving conditions and road surface conditions.

Means for solving the problems are as follows: 1) According to the present invention, the present invention has one input member and two output members, one for the rear wheels and one for the front wheels. A rental differential device that performs a differential operation between the two members, a 00 input member located on the center eye 7 differential, and two of the two output members are connected to each other with a variable transmission torque 8. A method for controlling a four-wheel drive device comprising: a differential limiting device that limits the differential operation of a center differential device; and a control device that controls the torque capacity of the differential limiting device. In this step, the rear wheel rotation speed and the front wheel rotation speed are detected, and the transmission 1 torque capacity of the differential limiting device is adjusted so that the difference between the rear wheel rotation speed and the front wheel rotation speed deepens to a value not exceeding a predetermined value of 11. This is achieved by a control method 11 characterized in that the suspension is completely controlled.

J that does not fall below a predetermined value: The difference between the number of rotations of one wheel and the number of rotations of the front wheels that should be J is a tight corner brake.
It may be set variably depending on the steering angle in view of the degree of the r phenomenon.

The differential limiting device used to implement the control method according to the present invention may be any device that can freely change the transmission torque of eight torques according to an external control signal. A plate clutch, an electromagnetic Baug clutch, etc. may be used. Effects and Effects of the Invention According to the U++ method for controlling a four-wheel drive device according to the present invention, the difference between the rear wheel rotation speed and the front wheel rotation speed is maintained at a predetermined value or less. is allowed, and the development of a tight coat brake in which the difference in rotational speed between the front and rear wheels does not exceed a predetermined value is avoided, as well as the generation of circulating torque at the time of starting or the like is avoided. If the front or rear wheels are unable to transmit driving force to the road surface and slip occurs, and this causes the difference between the rear wheel rotation speed and the front wheel rotation speed to exceed a predetermined value, the difference exceeds the predetermined value. The transmission torque capacity of the differential vj limiting device is increased to prevent the difference from increasing, and the differential operation of the center gamma differential device C is gradually limited, so that the vehicle gradually approaches a four-wheel drive state in which the front and rear wheels are directly connected. This improves the driving performance of the vehicle, improves the ability to traverse rough roads, and allows the vehicle to traverse rough roads.

The allowable RFI rear wheel rotation speed difference to avoid the tight corner braking phenomenon increases as the steering angle increases, so this allowable RFI rear wheel rotation speed difference should be set according to the steering angle. This makes the effect of both avoiding the tight corner braking phenomenon and avoiding a decrease in full-width driving force due to slippage even more significant.

EMBODIMENTS The present invention will now be described in detail with reference to embodiments with reference to the accompanying drawings.

FIG. 1 is a dimensional skeleton diagram of a four-wheel drive system used to implement the control method according to the present invention. In the figure, 1 indicates an internal combustion engine, and the internal combustion engine is located at 141 at a curved part of the vehicle.
A vehicle automatic transmission 2 and a four-wheel drive transfer device 3 are connected in sequence to the rear of the internal combustion engine.

The automatic speed changer 2 for Φ vehicles includes a hydraulic type 1 to lux converter 5 of a general structure provided in a converter coove 4 and a tooth width type transmission 7 provided with an H4 in a transmission sheath 6. The rotary power of the internal combustion engine 1 is connected to the output shaft (crankshaft, not shown) of the internal combustion engine 1 through the input member E3 of the hydraulic torque converter 5. The signal is applied to the transmission 7 via the . The transmission 7 is a well-known transmission comprised of a double gear mechanism, which switches between a plurality of gear stages, and whose gear change is controlled by a hydraulic control device 9. ing.

For four-wheel drive] - The transfer device 3 is a planetary center differential 3121 for full-time 4WD.
0, and the center f-7 rental shaft 10 has a carrier 11 as an input member to which rotational power is applied from the transmission 7, a planetary binion 12 held by the carrier, and a planetary binion 12. The ring gear 14 is connected to the rear wheel drive shaft 15, and the tatami number gear 13 is a three-way front wheel drive intermediate shaft coaxial with the rear wheel drive J axis 15. 16. The four-wheel drive transfer device 3 is provided with a front wheel drive shaft 17 parallel to the front wheel drive intermediate shaft 16, and the front wheel drive intermediate shaft 1G and the MI wheel drive shaft 17 are attached to each of them. The driving connection is made by a sprocket 18 and an endless chain 20 that meshes with one of the sprockets.

Note that the center differential device 10 is configured so that the front and rear wheel torque distribution ratio is commensurate with the TIRF load 111 distribution ratio at the time of maximum starting acceleration due to its own idle ratio.

The four-wheel drive transfer/device 3 is provided with a hydraulically operated differential control clutch 21 that selectively connects the number gear 13 and the ring gear 14, and the differential control clutch operates on all four wheels! This is carried out by the hydraulic control II device 22 provided at the transfin holder 33.

As shown in Fig. 2, the K first a, II iD clutch 21 is a hydraulically operated wet multi-disc clutch.
The oil supplied to the oil chamber 36 of the hydraulic servo Ff35)
11th, F causes the servo piston 37 to return to the spring 38
I decided to move to the right in the figure against the spring force of 1-
Center differential range (Ile device'I
The O-ring gear 133 and the ring gear 14 are connected to each other, and the transmission torque capacity is proportionally increased in accordance with an increase in the servo oil pressure supplied to the oil chamber 36.

The oil n'a-control device 22 changes the speed 012 to M for medium vehicles.
1 A breather TI regulator valve 40 which receives hydraulic pressure from the A oil pump 39 contained therein and regulates it to a predetermined hydraulic pressure, and an electromagnetic vehicle hydraulic control valve which receives hydraulic pressure from the pressure regulator valve 40. The valve 41 includes a boat a connected to the oil chamber 36 of the hydraulic servo device 35, a hydraulic boat b supplied with hydraulic pressure from the pressure regulator valve 40, etc.
Drain boat C is connected to boat A when the power is turned on.
is connected to hydraulic boat b, while boat a is connected to drain boat C when the power is not energized. The servo oil pressure control valve 41 is given a pulse signal of a predetermined duty ratio from the υ control quantity 45, and from this, the servo oil control valve 41 sends servo oil pressure of a magnitude corresponding to the duty ratio to the hydraulic servo device 35. The oil is supplied to the oil chamber 36.

One end of a rear propeller shaft 24 is connected to the rear wheel drive shaft 15 via a universal joint 23 .

One end of a front propeller shaft 26 is connected to the front wheel drive shaft 17 via a universal joint 25 . The front propeller shaft 26 extends approximately parallel to the axis on one side of the vehicle automatic transmission 2, and is connected to the front differential device 30 by a universal joint 27 and an intermediate connecting shaft 28 at the other end.
The input 11 is connected to one end of a drive pinion shaft 31. The drive pinion shaft 31 is the internal combustion engine 1
It is rotatably supported by a differential case 32 that is integrally molded with a cast iron A-il pan 29.

A drive pinion 33 having a heavy width is provided at the end of the drive pinion shaft 31, and the drive pinion meshes with a ring gear 34 of 30 in the front differential device.

The hydraulic control devices 9 and 22 are operated based on control signals from the electric control device 45 to control the gear shift of the gear shifter 7 and the transmission 1-lux control of the differential control clutch 21. ing. The control device 45 includes a micro-combination device having a general structure, and transmits information regarding the rear wheel rotation speed from the 19th wheel rotation speed sensor 46r to the front wheel rotation speed sensor 46f.
Information on the throttle opening of the internal combustion engine 1 is sent from the throttle opening sensor 47, and information about the throttle opening of the internal combustion engine 1 is sent from the manual shift position sensor 48 to the manual shift position sensor 48.
Information regarding the L full shift range is sent to the steering angle sensor 49.
The transmission device 7 is given information regarding the steering angle of the vehicle, and basically follows a predetermined shift pattern according to the manual shift range, the middle speed determined by the rear wheel rotation speed or the front wheel rotation speed, and the throttle opening degree. outputs a control signal for controlling the gear shift to the hydraulic control unit 9;
In addition, a pulse signal sequence with a predetermined j″-r − i − i ratio is used to control the 1 m torque capacity of the differential control clutch 21 according to the difference between the rear wheel rotation speed and the front wheel rotation speed and the steering angle. ) is output to the servo hydraulic control valve 41.

Specifically, the transmission torque capacity TO of the differential υlOtl clutch 21 is controlled by the flowchart ↑ as shown in FIG.
It is carried out according to the following.

That is, a predetermined value ΔNset is determined according to the steering angle, and when l-ΔN between the rear wheel rotation viN r and the front wheel rotation speed N[ is less than the predetermined value ΔN Set, the differential braking ta clutch 21 is applied.
The transmission torque capacity fflTc of the operation control clutch 21 is decreased by a predetermined one shift ΔTC, and when the rotational speed difference ΔN is greater than a predetermined value ΔNset, the transmission torque capacity of the operation control clutch 21 is increased by a predetermined value ΔTc. .

Control target rotation speed 'Ij: T: Certain predetermined value (1^ΔN s
et increases by 1J as the steering angle increases, as shown in FIG. However, if the steering angle is 0 degrees and °C is also specified (
1^ΔNSot is not set to zero. , circulation i~ is set to a value necessary to avoid silk occurrence.

As a result, Centadeino Allencial equipment purchase 10 μ Moe 1
As long as the wheel rotational speed difference ΔN does not exceed the predetermined value ΔNset, the differential Wh action is freely performed, thereby avoiding the tight corner braking phenomenon.
Also, the occurrence of circulating 1-lux at the time of starting is avoided.

The difference ΔN between the rear wheel rotation speed Nr and the front wheel rotation speed N[ is a predetermined value ("
When increasing by more than 1ΔNset, let 11
This is when either the 12th wheel or the front wheel burns on the road surface and slips, and at this time, the transmission torque capacity of the differential control clutch 21 is adjusted so that the front 19th rotational speed difference ΔN is maintained at a predetermined value ΔN set. Increasing Qi Tc by ΔTC is performed. As a result, at this time, the transmission torque capacity filTc of the differential control clutch 21 gradually increases, and the differential operation of the differential control device 10 is gradually restricted, and the drive state of the 111 cars gradually changes to a state in which the front and rear wheels are directly connected. , the rotation @ difference ΔN decreases, and the vehicle's initial performance improves, making it easier to traverse rough roads.

Note that the control method according to the present invention may be performed according to a flowchart as shown in FIG.

In addition to the device such as the differential υ control clutch 21 that connects the two output members of the center differential arm with a variable transmission torque capacity, as in the above embodiment, One of the two output members and the input member are struck.
It is also possible to connect fi'
71-like effects can be obtained.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto, and various embodiments can be made within the scope of the present invention. It will be obvious to those skilled in the art that there is a function C.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a four-wheel drive device used to implement the method for controlling a four-wheel drive device according to the present invention, and FIG. A schematic configuration diagram showing a control system of a control clutch,
FIG. 3 shows an embodiment of the control method for a four-wheel drive device according to the present invention, and FIG. 11 shows the control L1 target rotation in the method I) for controlling a four-wheel drive device according to the present invention. A graph showing an example of the setting characteristics of the numerical difference, FIG. 5 does not show another embodiment of the four-wheel drive control method according to the present invention.
It is. 1...Internal combustion engine, 2...Automatic transmission for vehicles, 3...
- Four-wheel drive transfer device, 4... converter coos, 5... hydraulic torque converter, 6... transmigrating case, 7... transmission, 8... input member. 9...Hydraulic pressure t, II control device, 10...Center differential 11 independent, 11...Carrier, 12...
Zora Netari Pinion, 13...Sangia, 14...
Ring gear, 15...1 crotch wheel drive initial shaft, 16...front wheel drive V'' intermediate shaft, 17...front wheel drive shaft, 1 (3, 19
... sprocket, 20... patient (asthma), 21
...Differential 1 control clutch, 22...Hydraulic control'ga
Device, 23... Universal joint, 24... Rear propeller shaft, 25... Universal joint, 26... Front propeller shaft, 27... Universal joint, 29... Oil pan, 30...
...F L1 point γ if7 ratio p) device, 31...
Drive pinion shaft, 32...diff? Rencilel case, 33... Drive pinion, 34... Ring gear, 35... Hydraulic servo device, 36... Oil chamber,
37... Revo piston, 39... Oil pump,
40...Pressure regulator valve, 41...
No. - Hydraulic controller! -[1- Le valve, 45...Control device, 46r...Rear wheel rotation speed sensor, 46''...Front wheel rotation speed sensor 1.

Claims (2)

[Claims] (1) A center differential device that has one input member and two output members for rear wheels and front wheels and performs differential operation between the rear wheels and front wheels, and the input member of the center differential device. and a differential limiting device that connects two of the two output members to each other with a variable transmission torque capacity to limit the differential operation of the center differential device, and a differential limiting device that controls the transmission torque capacity of the differential limiting device. In a method of controlling a four-wheel drive device having a control device that detects rear wheel rotation speed and front wheel rotation speed, the difference between the rear wheel rotation speed and the front wheel rotation speed does not exceed a predetermined value. A control method comprising controlling the transmission torque capacity of the differential limiting device so that the transmission torque capacity is maintained at a value. (2) A center differential device that has one input member and two output members, one for rear wheels and one for front wheels, and performs differential operation between the rear wheels and front wheels, and the input member of the center differential device. and a differential limiting device that connects two of the two output members to each other with a variable transmission torque capacity to limit the differential operation of the center differential device, and a differential limiting device that controls the transmission torque capacity of the differential limiting device. In a control method for a four-wheel drive device having a control device, the rear wheel rotation speed and the front wheel rotation speed are detected, and the difference between the rear wheel rotation speed and the front wheel rotation speed is determined according to the steering angle. A control method comprising controlling the transmission torque capacity of the differential limiting device so as to keep it at a value not exceeding a predetermined value.