JPS62261540A - Controlling method for four-wheel drive device - Google Patents

Abstract

PURPOSE:To make driving on a rough road performable under smooth starting, by performing an increase in the extent of transfer torque capacity in a differential limiting device of a center differential gear, with the smaller in an increasing rate, the larger at a time when revolving speed differential between front and rear wheels at an increment of the said capacity. 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 3 and an automatic transmission 2. This 4-wheel 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 which is controlled by a hydraulic controller 22 to be controlled by a controller 45 according to a driving state. In this case, an increase in the extent of transfer torque capacity in the differential control clutch 21 is made so as to be performed with the smaller in an increasing rate, the larger at a time when a revolving speed differential between front and rear wheels to be detected by each of speed sensors 46r and 46f at an increment of this transfer torque capacity.

Description

[Detailed Description of the Invention] fc,! l's field of use Book 1F, light, automobiles, etc.! The present invention relates to a method of controlling a four-wheel drive device used in 11 vehicles, and particularly to a method of controlling a four-wheel drive device that controls a center differential 7-range cell R1ff.

BACKGROUND ART As one of the four-wheel drive systems used for small wheels of automobiles, there is a center differential K1ff1 that performs differential operation between rear wheels and front wheels, and a center differential K1ff1 that performs differential operation between rear wheels and front wheels.
A four-wheel drive iA system has already been proposed, which includes: (1) a differential limiting device that limits the differential operation of the Renshall device;
No. 7 and Japanese Unexamined Patent Publication No. 55-72420.

``In four-wheel drive systems such as the series, due to the differential operation of the center differential 11 system! 1! 1 when turning the vehicle
) Due to the difference in turning radius between the four wheels and the rear wheels, the occurrence of tight corner braking (1M) can be avoided, but on the other hand, when driving on rough roads such as rainy roads, snowy roads, muddy roads, etc., multiple small wheels may If any one of the small wheels slips and loses driving force, a phenomenon occurs in which the driving force of all the small wheels decreases due to the differential operation of the center differential device, resulting in a significant reduction in traversing performance. 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.

Problem to be Solved by the Invention When the differential control clutch is engaged, the differential operation of the differential/rental device is prohibited, resulting in a four-wheel drive state in which the front and rear wheels are directly connected, which improves the ability to traverse rough roads. -F, but when there is a difference in rotational speed between the front and rear wheels due to slippage between the front and rear wheels relative to the road surface, the engagement of the differential control clutch suddenly occurs. If this occurs, the driving state of the vehicle will suddenly change to a four-wheel drive state in which the front and rear wheels are directly connected, and the vehicle will not be able to smoothly start over rough roads.

The present invention is improved so that even if the differential control clutch is engaged when one of the several wheels is slipping with respect to the road surface, the clutch can be crossed with a smooth start. The purpose of the present invention is to provide a method for controlling a four-wheel drive device.

Means for Solving the Problems 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, so that there is no difference between the rear wheels and the front wheels. A center differential device that performs operation, and two members of the input member and the other two output members of the center differential device are connected to each other with a variable transmission torque capacity to perform differential operation of the center differential device. a differential limiting device for limiting;
) In the υ control method of a four-wheel drive system, the transmission torque capacity of the differential limiting device is controlled by the control head that controls the transmission torque capacity of the differential limiting device. ) This is achieved by a control method characterized in that the larger the difference between the rear wheel rotation speed and the front wheel rotation speed when increasing the total one-herk capacity, the smaller the increase rate is.

The difference 111 between the rear wheel rotation speed and the front wheel rotation speed may be a rotation speed difference or a rotation speed ratio.

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 capacity according to an external control signal. Clutches, electromagnetic bower clutches, etc. are used. Effects and Effects of the Invention According to the method for controlling a four-wheel drive device according to the present invention, the transmission torque capacity of the differential limiting device for limiting or prohibiting the differential of the center differential device is increased depending on the rear wheel rotation speed at that time. Depending on the difference between the front wheel rotation speed and the difference, the larger the difference, the more gradually the vehicle is operated.As a result, when the differential operation of the center differential device is limited to the first release or is prohibited, the difference in front and rear wheel rotation speed is large. +'+r+4-wheel drive with direct connection to the rear wheels M(;J'<) The vehicle's driving performance gradually improves and the vehicle's traversing performance improves. It will be done soon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 is a skeleton diagram showing a four-wheel drive system used to implement the control method according to the present invention. In the figure, reference numeral 1 indicates an internal combustion engine, which is installed vertically at the front of the vehicle between the internal combustion lines, and an automatic transmission 2 for the vehicle is installed at the rear of the internal combustion engine.
and a four-wheel drive transfer device 3 are connected in this order.

Automatic gear shifting for vehicles! fi2 is a hydraulic torque converter 5 of a general structure arranged in an inverter case 4 and a south-central type transmission provided in a transmission case 6. J7, and is drivingly connected to the output shaft (crankshaft, not shown) of the internal combustion engine 1 by the inlet J member 8 of the hydraulic torque converter 5, so that the rotational power of the internal combustion engine 1 is transferred to the hydraulic torque converter 5. The signal is then applied to the transmission 7. The transmission device 7 is a well-known transmission device composed of a planetary gear mechanism or the like, and switches between a plurality of gear stages, and performs gear change control using hydraulic control.
t+ device 9.

The four-wheel drive transfer device 3 is an 11mm vehicle-type pink differential device 1 for full-time 4W+).
0, the pink differential device 10 has
It has a carrier 11 as an input member to which rotational power is applied from the transmission 7, a planetary binion 12 supported by the carrier, a sun gear 13 and a ring gear 14 meshed with the planetary binion 12, and the ring gear 14
is connected to the rear wheel drive shaft 15, and the sun gear 13 is connected to a sleeve-shaped front wheel drive intermediate shaft 16 that is concentric with the rear wheel drive shaft 15. 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 16 and the front wheel drive shaft 17 each have a sprocket 18 and a It is drivingly connected by an endless chain 20 meshing with 19.

The center differential 1tqio is configured so that the front and rear wheel torque distribution ratio is commensurate with the front and rear wheel torque distribution ratio at the time of maximum starting acceleration due to its own T1 star gear 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 operation of the differential control clutch is controlled by the four-wheel drive transfer device. This is performed by the hydraulic control device 22 provided at t'T3.

As shown in FIG. 2, the difference 17 control clutch 21 is a hydraulic servo-type wet multi-disc clutch, and the servo piston 37 is returned by the servo oil 11 supplied to the oil chamber 36 of the hydraulic servo device 35. By moving to the right in the figure against the spring force of the spring 38, the sun gear 13 and ring gear 14 of the center differential device 10 are connected in a torque transmission relationship, and the servo oil pressure supplied to the oil chamber 36 is increased. The transmission torque customer base will be increased proportionately.

The oil pressure $I In device 22 is a breath regulator valve 40 that receives oil pressure from an oil pump 39 built into the vehicle automatic transmission 2 and regulates the oil pressure to a predetermined oil pressure.
and an electromagnetic type hydraulic pressure control valve 41 to which hydraulic pressure is applied from a pressure regulator valve 40. The servo hydraulic control valve 41 is connected to a boat a connected to the oil chamber 36 of the hydraulic servo device 35,
It has a hydraulic boat b to which hydraulic pressure is supplied from a pressure regulator valve 40, and a drain boat C. When energized, boat a is connected to hydraulic boat b, whereas when de-energized, boat a is connected to drain boat 0. It is supposed to connect. A pulse signal with a predetermined duty ratio is given to the servo hydraulic control valve 41 by the control device 45, and from this, the servo hydraulic control valve 41 sends servo hydraulic pressure of a size according to the duty ratio to the oil chamber 36 of the hydraulic servo device 35. supply.

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

The front wheel drive shaft 17 has a universal joint 25 with a refrond groove [1].
One end of the bellows shaft 26 is connected. The front propeller shaft 26 extends approximately parallel to the axis of the automatic transmission 2 for I-vehicles on one side, and is connected at the other end by a universal joint 27 and an intermediate connecting shaft 28. Sissel device 3
The drive pinion shaft 31 is connected to one end of a drive pinion shaft 31 which is an input shaft of the motor. The drive pinion shaft 31 is rotatably supported by a differential case 32 integrally molded with a cast iron four-wheel pan 29 of the internal combustion engine 1.

A drive pinion 33 made of a bevel gear is provided at the end of the drive pinion shaft 31, and the drive pinion meshes with a ring gear 34 of a differential gear ζ0.

The hydraulic control I necks 9 and 22 are operated in response to a control signal from an electric control I neck 45 to control the gear change υ of the transmission 7 and the transmission torque of the differential control clutch 21. It has become. The control I device 45 has a general +v,
The built-in microphone ITI:'] includes a computer, and receives information related to the rear wheel rotation speed from the rear wheel rotation speed sensor 46r, and information about the front wheel rotation speed from the front wheel rotation speed sensor 46f.
The throttle 1m degree sensor 47 sends information on the throttle opening of the internal combustion engine 1, the manual shift position sensor 48 sends information on the manual shift 1 range, and the manual shift switch F-49 sends information on the throttle opening of the internal combustion engine 1. The V37 transmission is basically configured according to a predetermined shift pattern according to the vehicle speed and throttle opening, which are determined by the Mayu Al shift range and the rear wheel rotation speed or front wheel rotation speed. A control signal for controlling the gear shift is output to the hydraulic control device 9, and differential control is performed depending on whether the center differential lock mode is in effect and the difference between the rear wheel rotation speed and the front wheel rotation speed. A pulse signal having a predetermined duty ratio for controlling the transmission torque capacity fil of the clutch 2''1 is output to the servo hydraulic control valve 41.

Specifically, the control of the torque capacity ff1Tc of the differential control clutch 21 is performed according to a flowchart as shown in FIG.

First, in step 100, information is input from various sensors and switches. After step 100, the process advances to step 101.

In step 101, center differential 7 range p 0
It is determined whether or not it is in the lock mode, that is, whether or not the differential control Clara 1 is engaged.

Differential control clutch - When engaged, proceed to step 102;
On the other hand, if the differential control clutch is not engaged, the process advances to step 109.

In step 102, at this time,
Differential control clutch 2 is activated depending on vehicle speed, gear position of transmission, etc.
The control target servo oil pressure pSt of 1 is determined. After the slap 102, the process proceeds to step 103.

In step 103, the difference ΔN between the rear wheel rotation speed Nr and the front wheel rotation speed N'' is calculated.Step 1
After step 03, the process advances to step 104.

In step 104, it is determined whether or not the front and rear wheel rotational speed difference ΔN is zero. When ΔN=O, that is, when there is no difference in rotation speed between the front and rear wheels, the process advances to step 108, and ΔN
=O, that is, when there is a difference in the rotational speed of the front and rear wheels, the process proceeds to step 105.

In step 105, the increase rate k of the lift-bore oil pressure is determined in accordance with the characteristic shown in FIG. 4 in accordance with the rotational speed difference ΔN between the front wheels. The servo oil pressure increase rate decreases as the front and rear wheel rotational speed difference ΔN increases, and is set to zero when the front and rear wheel rotational speed difference ΔN is equal to or greater than a predetermined maximum value ΔNwax. After step 105, the process proceeds to step 106.

In step 106, the hydraulic pressure 1 is actually controlled.
) 3 to the current actual servo oil pressure ps by kpst. After step 106, the process proceeds to step 107.

In step 107, it is determined whether or not the new servo oil pressure l)3 determined in step 106 is greater than the control 1 servo oil pressure PSt determined in step 102. When ps≧PSt, the process proceeds to step 108, whereas when ps≧Pat, the process proceeds to step 110.

In step 108, the servo oil pressure Ps to be controlled υ
The control target servo oil pressure p determined in step 102
St is set. After step 108, the process proceeds to step 110.

Sudet/109 is differential, TJII control clutch 21
This is a step that is executed when the vehicle is not in use, and in this step 109, the servo oil pressure PS to be controlled is set to zero. After step 109, the process advances to step 110.

In step 110, step 106, step'
108 or the control servo hydraulic pressure PS1 determined in step 109. :J: The servo hydraulic control valve 4'1 outputs a pulse signal of the fl-di ratio according to the servo hydraulic control valve 4'1. As a result, the oil pressure value ps is supplied to the oil chamber 3G of the hydraulic servo device 155, and the transmission torque capacity of the differential control clutch 21 is controlled accordingly.

By repeatedly executing the flowchart as described above at predetermined intervals, Z:! j+ a+! The oil pressure of the I control clutch 21 and the difference in rotational speed between the front and rear wheels change as shown in FIG. That is, the larger the M1 rear wheel rotation speed difference ΔN at the start of engagement of the differential control clutch 21, the more
- Even if the engine oil pressure gradually increases at a low level and there is a large difference in rotational speed between the front and rear wheels when the differential control clutch 21 is engaged, the engagement of the differential control clutch 21 will be instantaneously and rapidly. It is carried out gradually according to the difference in the rotational speed of the rear wheels.
The restriction or prohibition of the differential operation is gradually carried out as the difference in rotational speed between the front and rear wheels increases. As a result, sudden changes in the driving state of the vehicle can be avoided, and smooth start-up can be achieved when traversing rough roads.

Furthermore, when the difference in rotational speed between the front and rear wheels ΔN is greater than or equal to the maximum value ΔN wax, the differential control clutch 21 is not engaged in order to ensure the durability of the differential υ control clutch 21.

Further, when the difference in rotational speed between the front and rear wheels ΔN is zero, that is, when there is no difference in the rotational speed between the front and rear wheels, the U differential control clutch 21 is engaged immediately so as to have good responsiveness. When there is no difference in the rotational speed of the IyJ rear wheels, even if the differential control clutch 21 is engaged immediately, the driving state of the vehicle does not change substantially, and therefore the driving state of the vehicle does not change suddenly. .

As mentioned above, the engagement speed of the differential control clutch 21 is controlled by v in accordance with the difference in the rotational speed of the rear wheels. B like to do.

If the servo oil pressure Ps is controlled according to the flowchart shown in FIG. The rate of increase k may be uniquely determined only by the difference in rotational speed between the front and rear wheels at the start of engagement of the λ dynamic control clutch 21; becomes as shown in FIG.

FIG. 7 is a flowchart showing another embodiment of a control method for four-wheel drive #1 according to the present invention.

Note that steps 200 to 204 in this 70-chart are substantially the same as steps 100 to 104 in the flowchart shown in FIG. 3, so their explanation will be omitted.

In step 205, a ΔN is subtracted from the υ control target servo oil pressure control t determined in step 202 to determine the servo oil pressure ps to be 1II3 ill. After step 205, the process proceeds to step 206.

In step 206, it is determined whether the servo oil pressure ps determined in step 205 is greater than zero. When ps > Q, proceed to step 209,
On the other hand, if Pa >O'r, the process proceeds to step 208.

In step 208, the engine oil pressure ps to be controlled is made zero. After step 208, the process advances to step 209.

In step 209, the 1ilJ determined in step 2.05, step 20, or step 208 is
(V-bo oil pressure control is performed using the servo oil pressure PS which should be 11. In other words, a pulse signal with a duty ratio corresponding to the servo oil pressure Pa is output to the servo oil pressure controller 1-o-ru valve 41. As a result, Differential aIlIIl
The servo oil pressure of the oil pressure value ps is supplied to the oil chamber 36 of the hydraulic servo device 35 of the l clutch 21, and this servo oil pressure increases the transmission torque capacity of the differential control clutch 21 to υJ11.
11.

By repeating the flow boot 11 as described above, the differential 1. The II control clutch 21 is engaged gradually at a low speed, and when there is no difference in the rotational speed of the front and rear wheels when the differential control clutch 21 starts to engage, the engagement is immediately carried out. In addition, in this case as well, the sword IJJυ control clutch 2
If the difference in rotational speed between the front and rear wheels at the start of engagement in step 1 is greater than or equal to a predetermined value, the value aΔN becomes larger than the control target servo oil pressure Pst in step 205, so that the differential υ11
11 clutch 21 is prohibited from engaging.

The engagement control 911 of the differential control clutch 21 as described above can be used in various 1. It may also be performed at the time of automatic engagement, which is performed based on the +3 requirement and 1;4.

In addition, a differential control device such as the differential control Clara F-21 has a center differential cell, in addition to a device that connects two output members of a center differential device with variable transmission torque capacity as in the above-mentioned embodiment. It is also possible to connect one of the two output members of the armor and the human-powered member, that is, the carrier, with a variable transmission torque capacity, and in this case, the same effects as in the above-mentioned embodiments can be obtained. It will be done.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to these, and it is understood that various embodiments can be made within the scope of the present invention. It will be clear to those skilled in the art.

[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. 2 is a schematic diagram showing a four-wheel drive device used to implement the method for controlling υJ of a four-wheel drive Vt position according to the present invention. 2 is a schematic configuration diagram showing the control system of the first control vehicle, FIG. 3 is a flowchart showing an embodiment of the control method for a four-wheel drive device according to the present invention, and FIG. 4 is a diagram showing the control method according to the present invention (before and after A graph showing the servo oil pressure increase rate characteristics with respect to the wheel rotation speed difference, Figure 5 is a four-wheel drive system according to the present invention.
A graph showing changes over time in the servo oil pressure and the difference in the rotational speed of front and rear wheels in the control method of the J device, and Fig. 6 is a graph showing another example of changes over time in the servo oil pressure and the difference in the rotational speed of the front and rear wheels. , FIG. 7 shows the four-wheel drive device fl, II according to the present invention.
Another example of the control method is O-Booyard. 1...Internal combustion engine, 2...Automatic transmission for vehicles, 3...
- Four-wheel drive transfer device, 4... converter case, 5... hydraulic torque converter, 6... transmission case, 7... transmission device, 8... input member. 9... Hydraulic pressure i, IJ lit device, 10... Center differential Kn, 11... Carrier, 12...
... Planetaribinion, 13... Zangia, 14.
...Ring gear, 15...Rear wheel drive shaft, 16...Front wheel drive intermediate shaft, 17...Front wheel drive shaft, 18.19.
...Sprocket, 20...Endless chain, 21...
・Differential t, II control clutch...oil Jf, I+
! I control device! ? , 23... Universal joint, 24... Rear propeller shaft, 25... Universal joint, 26... Front propeller shaft, 27... Universal joint, 29... Oil pan, 30... Front Differential device, 31
...Drive pinion shaft, 32...Differency II Lucus, 33...Drive pinion, 34...
・Ring gear, 35...Hydraulic length-bow device, 36...
Oil chamber, 37...Servo piston, 39...Oil pump, 40...Blessy jI regulator valve, 4
1... Servo hydraulic control valve, 45... Control device, 46r... Rear wheel rotation speed hinge, 46r...
Moe wheel rotation failure sensor. 47...Throttle opening sensor, 48...Manual shift position sensor, 49...Manual changeover switch special E1 Applicant: Toyota Jishoichi Co., Ltd.
Attorney Patent Attorney Masatake Akashi 3 Figure
0 Front and rear wheel rotational speed difference ΔN -11 Figure 7-

Claims (1)

[Claims] A center differential device includes 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 the front wheels; a differential limiting device that connects two of the two output members with each other with a variable transmission torque capacity to limit the differential operation of the center differential device; and a control 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 method characterized in that the control is performed at a smaller increase rate as the time increases.