JPH0771897B2 - Wheel rotation speed control mechanism - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wheel rotation speed control mechanism for independently controlling the rotation speeds of wheels of a four-wheel drive vehicle.

[Conventional technology]

In order to improve the running performance and maneuverability of the vehicle, it is possible to control the torque transmitted from each wheel to the road surface for each wheel. Therefore, in a four-wheel drive vehicle,
As shown in FIG. 4, front and rear drive shafts 1 and 2 and an axle 3l,
The continuously variable transmissions 5l, 5r, 6l, 6r are interposed between the 3r, 4l, 4r, and the speed ratios of the continuously variable transmissions 5l, 5r, 6l, 6r are changed to change the wheels 7l, 7r, 8l. , Rotation speed of 8r, wheels 7l, 7r, 8l,
Some control the transmission torque by changing it every 8r. The output rotation of the engine 9 is transmitted to the front wheel drive shaft 1 and the rear wheel drive shaft 2 via the propulsion shaft 10.

[Problems to be Solved by the Invention]

However, in the above-described conventional rotation speed control mechanism, the continuously variable transmissions 5l, 5r, 6l, 6r are interposed between the respective axles 3l, 3r, 4l, 4r and the drive shafts 1, 2. Therefore,
It means that the continuously variable transmissions 5l, 5r, 6l, 6r constantly transmit torque during traveling. Therefore, the continuously variable transmissions 5l, 5r, 6l, 6r are required to have high durability and high reliability, which increases the cost. In addition, continuously variable transmissions 5l, 5r,
If either 6l or 6r fails, the axles 3l, 3r, 4
Either l or 4r will not be driven, and you will not be able to drive.

Furthermore, since one continuously variable transmission is required for each wheel 7l, 7r, 8l, 8r, at least four continuously variable transmissions 5l, 5r, 6l, 6r are required, which increases the vehicle weight. At the same time, the installation space must be secured, and the cost also rises.

In view of this, the present invention reduces the number of continuously variable transmissions to be mounted as much as possible and prevents torque from being directly transmitted to the wheels to reduce the load applied to the continuously variable transmission as much as possible. Is intended to provide.

[Means for Solving the Problems]

In order to achieve the above object, a rotation speed control mechanism according to the present invention includes a center differential including an input unit to which a driving force from an engine is input and two output units to which output shafts are connected, respectively. A front differential having an input portion into which driving force from one output portion of the center differential is input via the first output shaft and two output portions to which front wheel output shafts connected to the front wheels are respectively connected And an input unit to which the driving force from the other output unit of the center differential is input via the second output shaft and two output units to which the rear wheel output shafts connected to the rear wheels are respectively connected. In a four-wheel drive vehicle having a rear differential equipped with, a continuously variable transmission is provided between two output portions of each of the differentials. Is characterized in that the driven coupling Te.

[Work]

For example, if the speed ratio of the continuously variable transmission provided in combination with the rear differential is changed, the rotational speeds of the left and right rear wheels can be changed respectively, and the left and right rear wheels can be changed from the engine via the rear differential. The torque transmitted is redistributed by the continuously variable transmission. For this reason, the torque transmitted to the road surface can be made larger, for example, by the right rear wheel than by the left rear wheel, and the running performance and maneuverability of the vehicle can be improved.

〔Example〕

Hereinafter, the rotation speed control mechanism according to the present invention will be specifically described based on the preferred embodiments shown in FIGS. 1 to 3. One embodiment is shown in FIGS. 1 and 2, and another embodiment is shown in FIG.

FIG. 1 is a schematic diagram showing the power transmission system of a four-wheel drive vehicle, in which the output rotation of the engine 12 is transmitted to the center differential 14. Center differential 14 has front wheels 16l, 1
It absorbs the difference in rotational speed between the 6r and the rear wheels 18l, 18r. One of the two output shafts of the center differential 14 is connected to the front output shaft 20, which is the first output shaft, and the other is connected to the other. The rear wheel propulsion shaft 22, which is the second output shaft, is connected.
The front wheel propulsion shaft 20 is an input shaft of a front differential 24, and the rear wheel propulsion shaft 22 is an input shaft of a rear differential 26. And the front differential 24
The front wheels 16l, 16r are driven by the front wheel drive shafts 28l, 28r, which are the front wheel output shafts, and the rear wheels 18l, 16r are driven by the rear wheel drive shafts 30l, 30r, which are the rear wheel output shafts of the rear differential 26.
l and 18r are driven.

A belt type continuously variable transmission 40 is combined with the center differential 14. The drive gear 20a is attached to the front wheel propulsion shaft 20 which is the first output shaft of the center differential 14, and the drive gear 2 is attached to the rear wheel propulsion shaft 22 which is the second output shaft.
2a are provided, and driven gears 41 and 42 meshing with these drive gears 20a and 22a are rotated to rotate pulleys 43 and 44 of the continuously variable transmission 40. These pulleys 43 and 44 have
Belt 45 is hung around. The diameters of the pulleys 43, 44 are continuously changed so that the pulleys 43, 44
The speed ratio between can be changed continuously.

A belt type continuously variable transmission 50 is combined with the front differential 24. Front wheel drive shaft 28
Drive gears 28a and 28b are provided on l and 28r, respectively.
The driven gears 51 and 52 meshing with the a and 28b cause the pulleys 53 and 54 to
Rotates, and a belt 55 is stretched between the pulleys 53 and 54. Then, the diameters of the pulleys 53 and 54 are continuously changed to continuously change the speed ratio between the pulleys 53 and 54.

Further, a belt type continuously variable transmission 60 is combined with the rear differential 26. Rear wheel drive shaft 30
Drive gears 30a and 30b are provided at l and 30r.
Driven gears 61, 62 meshing with a, 30b make pulleys 63, 64
Rotates, and a belt 65 is stretched between the pulleys 63 and 64. Then, the diameters of the pulleys 63 and 64 are continuously changed to continuously change the speed ratio between the pulleys 63 and 64.

The operation of the rotation speed control mechanism shown in FIGS. 1 and 2 will be described below.

Fig. 2 shows the drive system for the rear wheels 18l and 18r.
If the rotation speed of _l is N _l , the rotation speed of the rear wheel 18r is N _r , the rotation speed of the pulley 63 is N _lv , and the rotation speed of the pulley 64 is N _rv , then N _l / N _r = N _lv / N _rv (1) Therefore, if the speed ratio of the continuously variable transmission 60 is changed, the rotational speeds of the left and right rear wheels 18l, 18r can be changed. The rear wheel 18
The difference between the rotational speeds of l and 18r is absorbed by the rear differential 26.

Further, since the torque T _o which is transmitted from the rear wheel propeller shaft 22 is evenly distributed in the rear differential 26, rear drive shaft
The respective torques T _ol and T _or transmitted to 30l and 30r are T _ol = T _or = T _o / 2 (2). However, with the continuously variable transmission 60, the left and right rear wheels 18
Since a difference occurs in the rotational speeds of l and 18r, torque is transmitted between the pulleys 63 and 64, and the magnitude of the transmitted torque is set to the second value.
As shown in the figure, if expressed as T _v including the direction, the left and right rear wheels 18
The torques T _l and T _r transmitted to l and 18r are T _l = T _o / 2−T _v ………… (3) T _r ＝ T _o / 2 + T _v ………… (4) Torque transmitted to wheels 18l, 18r T _l , T _r
Can make a difference.

Therefore, the torques to be transmitted from the left and right rear wheels 18l, 18r to the road surface can be made different, the running performance of the vehicle can be improved, and the maneuverability becomes stable.

The same applies to the front wheel drive shaft 20 and the rear wheel drive shaft 22 that are the output shafts of the center differential 14, and the front wheel drive shafts 28l and 28r that are the output shafts of the front differential 24.

FIG. 3 shows another embodiment, which is a diagram showing a rear wheel drive system corresponding to FIG. In this embodiment, between the driven gear 61 and the pulley 63, and between the driven gear 62 and the pulley 64.
The clutches 66 and 67 are interposed between the
By continuously engaging and disengaging the clutches 66, 67, a continuously variable transmission
60 can be activated or deactivated. That is, if the clutches 66 and 67 are connected, the continuously variable transmission 60 functions, and the same operation as that of the embodiment shown in FIG. 2 described above is performed. The rear wheel drive system may be provided without the transmission 60. The clutches 66 and 67 are provided between the driven gear 61 and the pulley 63 and between the driven gear 62 and the pulley 64, respectively.
It may be either between 61 and the pulley 63 or between the driven gear 62 and the pulley 64.

When the vehicle normally travels straight, the clutches 66, 67
By disconnecting, the transmission torque is evenly distributed to the rear wheels 18l and 18r by the rear differential 26, and stable running can be performed. Further, for example, in the case where the continuously variable transmission 60 breaks down and if the failure hinders the running of the vehicle,
Disengagement of the clutches 66, 67 will not prevent the vehicle from running.

Note that each of the continuously variable transmission 40 combined with the center differential 14 and the continuously variable transmission 50 combined with the front differential 24 can be provided with a clutch.

Although the belt-type continuously variable transmissions 40, 50, 60 are used in this embodiment, the belt-type continuously variable transmissions are not the only type.

〔The invention's effect〕

As described above, according to the rotation speed control mechanism of the present invention, the torque generated by each wheel can be controlled by controlling the output rotation speed from the differential, so that the running performance and maneuverability of the vehicle are improved. Can be made.

Moreover, since the driving torque is not directly transmitted to the wheels by the continuously variable transmission, but only the difference between the torques of the left and right wheels is transmitted, the burden on the continuously variable transmission is small, the cost is low, and the life is long. It is possible to provide a long rotation speed control mechanism. Further, since the drive torque is not directly transmitted, the vehicle will not be disabled even if the continuously variable transmission fails.

Further, since it is sufficient to provide the continuously variable transmissions in the number corresponding to the number of differentials, it is possible to reduce the number of continuously variable transmissions and reduce the cost.

[Brief description of drawings]

The drawings show a preferred embodiment of the rotation speed control mechanism according to the present invention. 1 and 2 show one embodiment, FIG. 1 is a schematic diagram showing a power transmission system of a four-wheel drive vehicle, and FIG. 2 is a diagram showing a rear wheel drive system in FIG. Is. FIG. 3 shows another embodiment, and is a diagram showing a drive system for the rear wheels corresponding to FIG. FIG. 4 is a schematic diagram showing a power transmission system of a vehicle provided with a conventional rotation speed control mechanism, and corresponds to FIG. 12 …… Engine 14 …… Center differential 16l, 16r …… Front wheel, 18l, 18r …… Rear wheel 20 …… Front wheel propulsion shaft, 22 …… Rear wheel propulsion shaft 24 …… Front differential 26 …… Rear differential 28l, 28r ...... Front wheel drive shaft, 30l, 30r …… Rear wheel drive shaft 40 …… CVT 43,44 …… Pulley, 45 …… Belt 50 …… CVT 53,54 …… Pulley, 55 …… Belt 60 …… continuously variable transmission 63, 64 …… pulley, 65 …… belt

Claims (1)

[Claims] 1. A center differential having an input section to which a driving force from an engine is input and two output sections to which output shafts are respectively connected, and a driving force from one output section of the center differential is the first. Drive from the other output part of the center differential, and a front differential having an input part input via the one output shaft and two output parts to which front wheel output shafts connected to the front wheels are respectively connected. In a four-wheel drive vehicle having a rear differential having an input section to which force is input via the second output shaft and two output sections to which rear wheel output shafts connected to rear wheels are respectively connected The rotational speed of a wheel characterized in that the two output parts of each of the differentials are drivingly connected to each other via a continuously variable transmission. Degree control mechanism.