JPH01215626A - Four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To realize the stable four-wheel driving state even during the constant- speed driving run by differing the gear ratios of the front and the rear final stage deceleration gears from each other to give a variation in turning speed to a viscous coupling and to transmit the driving force according to the variation in speed to a driving shaft part. CONSTITUTION:A viscous coupling 7 is connected via transmission means 4 to 6 to the main shaft 3 of a transmission gear 2 connected to an engine body 1. The main shaft 3 is connected to a rear-wheel-side final deceleration gear 19 via transmission means 16 to 18. On the other hand, a front drive shaft 10 connected to the viscous coupling 7 is connected to a front-wheel-side final deceleration gear 15 transmission means 12 to 14. In such constitution, the gear ratios of the front and rear final deceleration gears 15 and 19 are made different from each other. Thus the variation in turning speed is forcedly given to the viscous coupling 7 and the driving force according to the variation in turning speed is transmitted to a front propeller shaft 13.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a full-time 4
Regarding wheel drive vehicles.

[Conventional technology] Conventional viscous coupling type full-time four-wheel drive vehicle (
In FR vehicles), the rotational driving force of the engine is transmitted from the main shaft to the rear propeller shirt 1 through the rear wheel final reducer, and then from the main shaft to the viscous coupling, the front propeller shaft, and the rear propeller shaft. The power is transmitted to the front wheels via the final reduction gear on the front wheel side.

In this case, when relative rotation occurs between the front wheels and the rear wheels, the driving force (torque) corresponding to the rotation difference is transmitted to the front wheels (
(See Figure 2).

[Problems to be solved by the invention] However, in such a conventional viscous coupling type full-time four-wheel drive vehicle, when driving at a normal constant speed, the rotation difference between the front wheels and the rear wheels is Because there are almost no
The transmission torque is limited or very small, and two-wheel drive (two-wheel drive) is possible.
WD> running condition (see Figure 3, chain double-dashed line A)
. For this reason, when driving at a normal constant speed, four-wheel drive (4WD) is required.
> Compared to the current situation, there was a problem in that stable running could not be achieved.

Furthermore, on low μ roads such as snowy roads, when the main drive wheels slip, a rotational difference occurs in the viscous coupling, and a driving force corresponding to the rotational difference is transmitted.

In this way, since it is based on the slip (loss) of the main drive wheels, there is a problem of poor fuel efficiency.

Means for Solving Problem E] The present invention has been made in view of such conventional problems, and by changing the gear ratio of the front and rear final reduction gears, a few percent of the viscous coupling is reduced. By forcibly generating a rotational difference and constantly transmitting the driving force corresponding to the rotational difference to the viscous drive shaft, it is possible to achieve stable driving in 4WD mode even when driving at a constant speed. The aim is to provide a four-wheel drive vehicle that can also improve fuel efficiency.

In order to achieve this object, the present invention provides a viscous coupling type full-time four-wheel drive vehicle that transmits the rotational driving force of the engine to the front wheels or rear wheels via a viscous coupling. The gear ratio of the final reduction gear on the rear wheel side is changed.

[Operation] In the present invention, since the gear ratio of the front wheel final reducer and the rear wheel final reducer is changed, a rotation difference occurs in the viscous coupling even when driving at a constant speed, and the Driving force is always transmitted to the viscous drive shaft side.

Therefore, even during normal constant speed driving, stable driving can be achieved in the 4WD state.

Furthermore, since the main drive wheels are not subject to slippage, fuel efficiency can be improved.

[Example 1 Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

First, to explain the configuration, in FIG. 1, 1 is an engine body, and 2 is a transmission connected to the engine body 1. A main shaft 3 that transmits the rotational driving force of the engine is rotatably housed within the transmission 2.

A drive sprocket 4 is integrally formed on the main shaft 3, and a chain 6 is installed between the drive sprocket 4 and the driven sprocket 5.

7 is a viscous coupling, and the viscous coupling 7 includes an outer plate 9 assembled to a case 8 connected to the driven sprocket 5, and an inner plate 11 assembled to the front drive shaft 10.
It has .

The outer plates 9 and the inner plates 11 are arranged alternately, and the case 8 containing these plates 9 and 11 is filled with approximately 90% silicone oil.

When a rotational difference occurs between the outer plate 9 and the inner plate 11, transmission of driving force begins due to the shear resistance of the silicone oil, and as the rotational difference increases, the transmitted torque also increases (see FIG. 2).

The front drive shaft 10 is connected to a front propeller shaft 13 via a universal joint 12, and the front propeller shaft 13 is connected to a front wheel final reduction gear 15 via a universal joint 14.

On the other hand, the main shaft 3 is connected to a rear propeller shaft V-foot 17 via a universal joint 16, and the rear propeller shaft V-foot 17 is connected to a universal joint 18.
It is connected to the rear wheel side final reduction gear 19 via.

Here, the front wheel side final reducer 15 and the rear wheel side final reducer 19
The gear ratios are different. In other words, the rotation of the viscous-driven front propeller shaft 13 is a few percent (for example, 1 to 2%) of that of the rear propeller shaft 17.
The gear ratio is set so that it is low (ifFR
RR).

In this way, a rotation difference of several percent is forced to occur in the viscous coupling 7.

Note that 20 is a front wheel that is attached to an axle 21 and is attached, and 22 is a rear wheel that is attached to an axle 23.

Next, the effect will be explained.

Gear ratio of front wheel final reduction gear 15 and rear wheel final reduction gear FM19! f F R<! f RR, the rotation of the front wheels 20 and rear wheels 22 is almost the same during normal constant speed driving, so there is a difference in rotation between the front wheels 1 to propeller shaft 13 and the rear propeller shaft 17. occurs.

The viscous coupling 7 absorbs this rotational difference, and the front propeller shaft 1 receives a driving force corresponding to this rotational difference.
3.

Therefore, as shown by the solid line B in FIG. 3, as the vehicle speed increases, the rotational difference increases and the transmitted torque also increases.

That is, by changing the gear ratio of the front wheel final reducer 15 and the rear wheel final reducer, a rotation difference of several percent is forcibly applied to the viscous coupling 7, and a driving force corresponding to the rotation difference is constantly applied. Transmitted to the viscous drive shaft side.

Therefore, even during normal constant speed driving, stable driving can be achieved in the 4WD state. Furthermore, since the main drive wheels are not subject to slippage, fuel efficiency can be improved.

In this embodiment, an FR-based 4-wheel drive vehicle in which the front wheels 20 are driven by a viscous coupling has been described as an example, but the present invention is not limited to this. Needless to say, it can also be applied to

[Effects of the Invention] As explained above, according to the present invention, by changing the gear ratio of the front and rear final reduction gears, a rotational difference is forcibly applied to the viscous coupling, and a driving force corresponding to this rotational difference is generated. Since the viscosity is always transmitted to the viscous drive shaft side, stable driving can be achieved in 4WD mode even when driving at a normal constant speed.

Furthermore, since the main drive wheels are not subject to slippage, fuel efficiency can also be improved.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the relationship between relative rotational speed and transmitted torque, and FIG. 3 is a graph showing the relationship between vehicle speed and transmitted torque. In the figure, 1...Engine body, 2...Transmission, 3...Main shaft, 4...Drive sprocket, 5...Driven sprocket, 6...Chain, 7...Viscous coupling , 8...Case, 9...Outer plate, 10...Front drive shaft, 11...Inner plate, 12.14, 16.18...Universal joint, 13...Front propeller shaft , 15...Front wheel side final reduction gear, 17...Rear propeller shaft, 19...Rear wheel side final reduction gear, 20...Front wheel, 21.23...Axle, 22...Rear ring. Patent applicant: Fuji Iron Works Co., Ltd.

Claims (1)

[Claims] In a viscous coupling type full-time four-wheel drive vehicle that transmits the rotational driving force of the engine to the front or rear wheels via a viscous coupling, the gear ratio of the final reduction gear on the front wheel side and the final reduction gear on the rear wheel side is changed. A four-wheel drive vehicle characterized by the following features: