JPH0377088B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention defines, for example, the front wheels as the main drive wheels and the rear wheels as the sub-drive wheels, and selectively switches between two-wheel drive driving using only the front wheels and four-wheel drive driving using the front wheels and rear wheels. The present invention relates to a power transmission device for a four-wheel drive vehicle.

In this type of four-wheel drive vehicle, for example, switching between driving the rear wheels (four-wheel drive) and stopping the drive (two-wheel drive) is performed using a clutch installed in the power transmission path for the rear wheels. This is generally done by using intermittent periods.

However, in the case of such a four-wheel drive vehicle, conventionally, in the case of two-wheel drive driving with only the front wheels as the main drive wheels, the rear wheel drive system after the clutch, that is, the propeller shaft, the final reduction gear,
The rear wheel operating mechanism is rotated needlessly due to rotational force transmitted from the rear wheel which is driven by the front wheel, which is a major cause of increased noise, deterioration of fuel efficiency, acceleration of wear, etc.

Conventionally, a gear-type differential mechanism was used as a differential mechanism for the rear wheels, but this gear-type differential mechanism generates quite a lot of noise and is large and heavy. Ta.

The present invention solves the above-mentioned problems by installing the clutch closer to the engine than the propeller shaft that transmits power to the driven wheels, and at the same time attaching the differential mechanism for the driven wheels to the freewheel. When traveling in two-wheel drive, by using the characteristic of the directionality of rotation transmission of the freewheel,
The present invention is characterized in that the power transmission path for the driven wheels closer to the engine than the final reduction gear for the driven wheels is not rotated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to drawings showing an embodiment in which a front wheel and a main drive wheel are defined, and a rear wheel is defined as a subordinate drive wheel.

In FIG. 1, 1 is an engine, and 2 is a transmission connected to the engine 1 via a main clutch 3. The drive gear 4 of the transmission 2 meshes with the final reduction gear 5 for the front wheels, thereby causing the left and right front wheels to FL and FR are now driven. Of course, the final reduction gear 5 for the front wheels and the left and right front wheels FL, FR
An appropriate type of differential mechanism is interposed between the axles 6 and 7, but as this is not the gist of the present invention, illustration is omitted.

A pinion 10 provided at the front end of a pinion shaft 9 meshes with the gear 8 integrated with the final reduction gear 5 for the front wheels, and the rear end of the pinion shaft 9 is manually operated for two-wheel drive driving or four-wheel drive driving. It is connected to a rear door rib shaft 12 via a sub-clutch (dog clutch) 11 for switching. The rear drive shaft 12 is
It is connected to a propeller shaft 14 via a universal joint 13, and the propeller shaft 14 is connected to the universal joint 1.
5 to the rear pinion shaft 16.

A pinion 17 provided at the rear end of the pinion shaft 16 is located within a rear axle housing 18 and meshes with a final reduction gear 19 for the rear wheels. The rear wheel final reduction gear 19 is mounted on the axle housing 1
The freewheel housing 20 is rotatably held within the freewheel housing 8. The freewheel housing 20 is connected to an axle 21 for the left rear wheel RL via a first freewheel 22, and is also connected to an axle 23 for the right rear wheel RR via a second freewheel 24. has been done.

The first and second freewheels 22 and 24 are
As shown in FIG. 2, an inner ring 25, an outer ring 26 having a plurality of recesses 26a for applying a wedge effect to the inner peripheral surface, and an outer ring 26 disposed between the two wheels 25 and 26 so as to be displaceable within the recesses 26a. multiple colo 27
and a cage 28 holding the roller 27. The inner ring 25 is integrated with the axle 21 or 23 by spline fitting, for example, and the outer ring 26 is attached to the freewheel housing 20 so as to rotate together therewith. When the outer ring 25 rotates, for example, in the clockwise direction (in the direction of the arrow) in FIG. The rotation of the outer ring 26 is transmitted to the inner ring 25 by the resulting wedge effect. When the outer ring 26 rotates counterclockwise in FIG. 2, the rollers 27 move toward the other end of the recess 26a in the circumferential direction, and the rotation of the outer ring 26 is similarly transmitted to the inner ring 25 by the wedge action. be done. However, the inner circle 25,
Even if the rollers 27 rotate clockwise or counterclockwise in FIG. 2, the rollers 27 are located in the circumferentially intermediate portion of the concave portion 26a and no wedge action occurs, and the rotation of the inner ring 25 is not transmitted to the outer ring 26. Become. In addition,
Since the structure and operation of such a freewheel itself have been well known, further detailed explanation will be omitted.

Next, the operation of the above configuration will be explained separately for two-wheel drive driving and four-wheel drive driving.

●When driving with two-wheel drive Sub clutch 11 is disengaged and the front wheel
Only the FL and FR wheels are driven, and the rear wheels RL and RR are rotated freely according to the vehicle's running speed and no driving force is applied to them. At this time, rear wheels RL, RR
The rotation of the first and second freewheels 22, 2
4 (More details: 1st and 2nd freewheel 2
Since the power is transmitted only to the inner ring 25) of the rear wheel 1, each component 1 forming the rear wheel power transmission path from the rear wheel final reduction gear 19 to the subclutch 11
6, 14, and 12 are not rotated at all and remain stopped.

●In the case of four-wheel drive driving The sub-clutch 11 is connected, and in addition to the front wheels FL and FR, the rear wheels RL and RR are also driven.
At this time, when driving straight, the left and right rear wheels RL,
Although RR is rotated at the same rotational speed, when turning, an appropriate rotational speed difference is given between the rear wheels RL and RR due to the differential operation of the first and second freewheels 22 and 24. In other words, when turning right in Figure 1, the left rear wheel RL is the right rear wheel.
It is necessary to rotate at a higher rotation speed than RR, but this difference in rotation speed is due to the fact that the inner ring 25 of the first freewheel 22 for the left rear wheel RL can rotate freely and faster than the outer ring 26. It is pulled out. Of course, in the case of a left turn, the differential action is provided by the second freewheel 24 in the same way as in the case of a right turn.

Furthermore, even if only one of the rear wheels RL and RR slips in mud or the like, driving force is always transmitted to the other rear wheel, providing a so-called non-slip differential function.

The differential operation of the freewheels 22 and 24 is also clear from, for example, Japanese Patent Publication No. 15245/1982, so a more detailed explanation will be omitted.

Although the embodiments have been described above, the present invention is not limited thereto, and can be similarly applied even when, for example, the rear wheels are used as the main drive wheels and the front wheels are used as the subordinate drive wheels. In addition, in the one shown in FIG. 1, free wheels 22, 2 are used as a differential mechanism for the front wheels.
It is also possible to use a configuration using 4. Furthermore, by adding a commonly used synchronizing mechanism to the sub-clutch 11, it is possible to shift from two-wheel drive to four-wheel drive without causing any shock even while the vehicle is running.

As is clear from the above description, the present invention has the following features:
When driving on two wheels, the power transmission system for the driven wheels is not rotated unnecessarily due to the rotational force transmitted from the rear wheels that are driven by the front wheels, reducing noise, improving fuel efficiency,
This is preferable in terms of preventing wear and the like. In addition, since a pair of freewheels can be used as the differential mechanism for the driven wheels, the structure is simpler, smaller, and lighter than when using a gear-type differential mechanism. , and generates less noise. Moreover, the differential mechanism that uses a pair of freewheels also has a non-slip differential function, which is extremely advantageous for this type of vehicle, which often drives on slippery surfaces such as snowy roads and mud. It is.

[Brief explanation of drawings]

FIG. 1 is a simplified overall system diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing an example of a freewheel. FL, FR...Front wheel (main drive wheel), RL, RR...
Rear wheel (slave drive wheel), 11...Clutch, 19...
(For slave drive wheels) Final reduction gear, 21, 23...
(For slave drive wheels) Axle, 22, 24...Freewheel.

Claims (1)

[Claims] 1. One of the front wheels and rear wheels is defined as a main drive wheel, and the other is defined as a sub-drive wheel to which power is transmitted via a propeller shaft, and two-wheel drive driving using only the main drive wheels is achieved by operating a clutch. In a four-wheel drive vehicle capable of selectively switching between four-wheel drive driving using a main drive wheel and a slave drive wheel, the clutch is installed closer to the engine than the propeller shaft, and the clutch is installed as a final reduction gear for the slave drive wheel. and the right driven wheel axle, and the final reduction gear and the left driven wheel axle are connected via freewheels, and both freewheels allow transmission from the final reduction gear to the left and right driven wheels. A power transmission device for a four-wheel drive vehicle, characterized in that the power transmission device for a four-wheel drive vehicle is configured to transmit rotation, but not to transmit rotation from the left and right driven wheels to the final reduction gear.