JPS6390438A - Transfer for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To make it possible to safely run on a bad road, by changing over a coupling change-over device into a direct coupling mode to stop the power distributing function of a viscous coupling during running on a bad road. CONSTITUTION:During running on a bad road, a coupling sleeve 15 in a coupling change-over device 12 is changed over onto the clutch gear 13 side so that a casing 5 of a viscous coupling 4 is directly coupled to a drive shaft 1 through the coupling sleeve 15 and a spline hub 14. Due to the direct coupling between the casing 5 and the drive shaft 1, the relative rotation between an outer disk 6 and an inner disk 7 by the viscous coupling 4 is inhibited so that the casing 5 is rotated integrally with the drive shaft 1, and therefore, torque power from an engine to the drive shaft is distributed directly to front and rear wheels. The allocation of power to the front and rear wheels is about 50 to 50 in such a condition that a coupling change-over device 12 is changed over into a direct coupling mode to lock the viscous coupling.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a full-time four-wheel drive vehicle transfer using a viscous coupling known as a viscous coupling.

(Prior Art) Conventionally, in a full-time four-wheel drive vehicle equipped with a viscous coupling known as a viscous coupling, power from the engine is obtained through a transmission by a four-wheel drive transfer, for example. Rotation is transmitted directly to the front wheels, and is transmitted to the rear wheels via a viscous coupling. This viscous coupling transmits drive torque according to the difference in rotational speed between the front and rear wheels, thus dynamically distributing drive torque between the front and rear wheels appropriately depending on the road surface and driving conditions. The so-called full-auto full-time 4WD function is realized.

(Problem to be solved by the invention) However, so-called full-auto, full-time four-wheel drive vehicles equipped with such a viscous coupling can run very smoothly and stably on low-μ roads such as snowy roads. On the other hand, when driving on rough roads, especially when starting on sandy ground, the drive wheels would dig into the sandy ground before the viscous coupling reached a rotational speed difference that would generate torque, resulting in the vehicle becoming stuck.

(Means for Solving the Problems) The present invention has been made in view of these conventional problems, and provides a viscous cup that enables easy emergency escape from a sandy stack when driving on a rough road. The purpose of the present invention is to provide a transfer for a full-time four-wheel drive vehicle equipped with a ring.

In order to achieve this object, the present invention distributes and transmits the power rotation from the engine obtained through the transmission to the front wheels and the rear wheels, respectively, and transfers the power to the front wheels or the rear wheels. In the transmission system, a plurality of inner disks are alternately arranged to be rotatable relative to a plurality of outer disks fixed in a case, and a viscous coupling filled with a high viscosity liquid is provided in the case. In a transfer for a full-time four-wheel drive vehicle, where one of the input and output shafts is fixed to the outer disk that is fixed to the case, and the other input and output shaft is fixed to the inner disk, the outer disk is fixed. A connection switching device is provided between the viscous coupling case and the shaft to which the inner disk is fixed, for switching the two to a direct connection state.

(Function) According to the configuration of the present invention, when the connection switching device is disconnected, the drive torque is applied to the rear wheels or front wheels via the viscous coupling in accordance with the rotational speed difference between the input and output. The transmission is performed and the so-called full-auto full-time 4WD function is demonstrated, while when necessary, such as when driving on rough roads,
By switching the connection switching device to the direct connection state, the power distribution function of the viscous coupling is stopped and the power rotation from the engine can be directly transmitted to the front and rear wheels, making it possible to drive with confidence even on rough roads. It is something.

(Example) FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

First, to explain the configuration, reference numeral 1 is a drive shaft that receives power rotation from the engine via a transmission. 2 is fixed, and transmits driving force directly to the rear wheels via the propeller shaft.

A sprocket gear 3, which is a drive side for transmitting power rotation to the front side, is installed on the drive shaft 1, which is a rear drive shaft, so as to be relatively rotatable.
A viscous coupling 4 known as a viscous coupling is provided between the drive shaft 1 and the rotating shaft 3a of the sprocket gear 3.

The viscous coupling 4 is fixed in a case 5 and has a plurality of outer disks 6 disposed in the axial direction, and inner disks 7 are alternately arranged to be relatively rotatable with respect to the outer disks 6. A case 5 in which a disk 6 and an inner disk 7 are provided is filled with a highly viscous liquid such as silicone oil.

The embodiment shown in FIG. 1 is an FR-based four-wheel drive because the power rotation is directly connected to the rear side by the main drive shaft 1. Therefore, the inner disk 7 in the viscous coupling 4 is fixed to the drive shaft 1. On the other hand, the case 5 equipped with the outer disc 6 is fixed to the rotating shaft 3a of the sprocket gear 3, and the drive shaft 1
serves as an input shaft for the viscous coupling 4, and a rotating shaft 3a of the sprocket gear 3 serves as an output shaft for the viscous coupling 4.

A front drive shaft 8 is arranged parallel to the drive shaft 1 on which the sprocket gear 3 is rotatably mounted, separated by a predetermined interaxial distance, and a sprocket gear 9 on the driven side is fixed to the front drive shaft 8. Rotation of the sprocket gear 3 that receives power rotation via the viscous coupling 4 is transmitted to the sprocket gear 9 via the chain 10, and the front drive shaft 8
A front flange 11 provided at the end of the shaft allows power rotation to be transmitted to the front wheels via a front propeller shaft (not shown).

In a transfer for a four-wheel drive vehicle equipped with such a viscous coupling 4, the present invention includes a case 5 to which an outer disk 6 of the viscous coupling 4 is fixed.
A connection switching device 12 is provided between the drive shaft 1 to which the inner disk 7 is fixed, and the drive shaft 1 to which the inner disk 7 is fixed.

This connection switching device 12 includes a clutch gear 13 integrally provided on the right side of the case 5 of the viscous coupling 4, a spline hub 14 fixed to the drive shaft 1, and a coupling that can be switched and moved in the axial direction on the spline hub 14. A sleeve 15 is provided, and when the coupling sleeve 15 is moved in the axial direction by the shift lever, the illustrated clutch gear 13 and spline hub 14 are disengaged from each other, and the coupling sleeve 15 is engaged with the clutch gear 13. The case 5 of the viscous coupling 4 can be switched between two positions: a switching position in which the case 5 of the viscous coupling 4 is directly connected to the drive shirt 1 via the coupling sleeve 15 and the splined hub 14;

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, in the switching state in which the coupling sleeve 15 of the connection switching device 12 is disconnected from the clutch gear 13 provided on the case 5 side of the viscous coupling 4 as shown in the figure, the drive shaft is not connected to the rear wheel side. 1, the power rotation from the engine obtained through the transmission is transmitted as is, and the power rotation is transmitted to the negative side, the front side, through the viscous coupling 4.

That is, in the viscous coupling 4, the inner disk 7 is rotated by the drive shaft 1, and the outer disk 6 is dragged by the stirring of high viscosity liquid such as silicone oil due to the rotation of the inner disk 7, and receives the power rotation, and the sprocket Power rotation is transmitted to the front drive shaft 8 via the gear 3, chain 10, and sprocket gear 9.

The transmission characteristic of the driving torque to the front side in this viscous coupling 4 is given by the rotation speed difference ΔN-Nr-4,lf, where the rear wheel rotation speed is Nr and the front wheel rotation speed Nf, and this rotation speed difference ΔN On the other hand, the torque generated to be transmitted to the front wheels is as shown in the characteristic curve in FIG. That is, the larger the rotational speed difference ΔN, the larger the generated torque transmitted to the front wheels.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, during normal driving, the coupling sleeve 15 of the connection switching device 12 is placed in the disconnected position shown, and power rotation according to the characteristics shown in FIG. 2 is transmitted to the rear side via the viscous coupling 4. Performs 4-wheel drive driving.

On the other hand, when driving on rough roads such as off-road where there is a risk of the vehicle getting stuck, the coupling sleeve 15 of the connection switching device 12 is switched to the clutch gear 13 side, and the coupling sleeve 15 and spline hub 14 are A case 5 of a viscous coupling 4 is directly connected to a drive shaft 1. Due to the direct connection between the case 5 and the drive shaft 1, relative rotation between the outer disk 6 and the inner disk 7 in the viscous coupling 4 is prohibited, and the case 5 rotates together with the drive shaft 1, allowing the drive shaft 1 to receive power from the engine. Rotation is now directly divided into the front and rear wheels, and the power distribution between the front and rear wheels is approximately 50:50 by switching the connection switching device 12 to the direct connection state and locking the viscous coupling 4, and is always fixedly determined. Since the driving force is distributed between the front and rear wheels, you can drive safely even on rough roads.

FIG. 3 is an explanatory diagram showing another embodiment of the present invention, and this embodiment shows a full-time four-wheel drive transfer based on FF by directly connecting power rotation from the engine to the front side.

That is, the power rotation from the engine obtained through the transmission is directly transmitted from the gear 18 to the front wheels via the differential unit 20. On the other hand, power rotation from the transmission is transmitted to the drive shaft 1 via gears 21 and 22, and a viscous coupling 4 is provided between the drive shaft 1 and the rear drive shaft 16.

That is, the case 5 of the viscous coupling 4 is fixed to the rear drive shaft 16, the outer disks 6 are arranged inside the case 5, and the drive shaft 1 is fixed to the inner disks 7 arranged alternately between the outer disks 6. are doing. Therefore, power rotation to the rear drive shaft 16 is performed via the viscous coupling 4.

Further, a connection switching device 12 is provided between the case 5 of the viscous coupling 4 and the drive shaft 1 to switch the two into a direct connection state. That is, the clutch gear 13 is integrally formed on the case 5 side of the viscous coupling 4, and the spline hub 14 is fixed to the drive shaft 1.
A coupling sleeve 15 provided to be able to switch freely in the axial direction with respect to the spline hub 14 allows shifting with the clutch gear 13 on the case 5 side.

Even in this FF-based four-wheel drive transfer shown in FIG. Power rotation is performed via the viscous coupling 4, and therefore, a so-called full-auto, full-time 4WD system is realized in which driving force is distributed between the front and rear wheels according to driving conditions.

On the other hand, when the coupling sleeve 15 of the connection switching device 12 is switched to the clutch gear 13 side, the 5 viscous coupling 4
The case 5 is directly connected to the drive shaft 1 via the coupling sleeve 15 and the spline hub 14, and the function of the viscous coupling 4 is stopped and the power rotation of the drive shaft 1 is directly transmitted to the rear drive shaft 16 via the case 5. As a result, it is possible to obtain a four-wheel drive state with a fixed driving force distribution in which the driving force distribution between the front and rear wheels is approximately 50:50 when driving on rough roads, etc., where the vehicle may be stuck.

In addition, in the connection switching device 12 in the above embodiment, the switching method was taken as an example in which the coupling sleeve 15 is fitted into the clutch gear 13 while the vehicle is stopped, but a synchronized mesh mechanism is provided. By doing so, the function of the viscous coupling may be stopped even while the vehicle is running, so that the four wheels can be directly connected.

In addition, the above embodiment was a poor example of transmitting power rotation to the front side by chain transmission, but
Even a system in which power rotation is transmitted to the front side through gear meshing can be applied as is.

(Effects of the Invention) As explained above, according to the present invention, the power rotation from the engine obtained through the transmission is distributed to each of the front wheels and the rear wheels and transmitted to the front wheels or the rear wheels. In the power transmission system, multiple inner disks are alternately arranged to rotate freely relative to multiple outer disks fixed inside the case, and a viscous coupling filled with high viscosity liquid such as silicone oil is installed inside the case. In a transfer for a full-time four-wheel drive vehicle, one of the input and output shafts is fixed to the case side of the viscous coupling that is provided and the outer disk is fixed, and the other input and output shaft is fixed to the inner disk side. A connection switching device is provided between the case of the viscous coupling to which the outer disk is fixed and the shaft to which the inner disk is attached, which switches the two into a direct connection state. Drive torque is transmitted to the rear wheels or front wheels according to the difference in rotational speed between input and output via a viscous coupling, and the function as a so-called full-auto full-time 4WD is demonstrated. When necessary, such as when driving on a rough road, by switching the connection switching device to the direct connection state, the power distribution function by the viscous coupling can be stopped and the power rotation from the engine can be directly transmitted to the front and rear wheels. Due to the locked state of the viscous coupling by this coupling device, even when driving on rough roads where the coefficient of friction of the road surface changes greatly, the fixed driving force distribution allows the vehicle to travel safely on rough roads.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, FIG. 2 is a graph diagram showing the torque transmission characteristics of the viscous compression ring shown in FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention. FIG. 1 driveshaft 2: rear flange 3.9: sprocket gear 4: viscous coupling (viscous coupling) 5:
Case 6: Outer disc 7: Inner disc 8: Front drive shaft 10: Chain 11: Front flange 12: Connection switching device 13: Clutch gear 14 Varnish spline hub 15: Coupling sleeve 16: Rear drive shaft 18.21, 22: gear

Claims (1)

[Claims] The power rotation from the engine obtained through the transmission is distributed and transmitted to the front wheels and the rear wheels, respectively, and the power transmission system to the front wheels or the rear wheels includes a plurality of power transmission systems fixed inside the case. A plurality of inner disks are arranged alternately so as to be relatively rotatable with respect to the outer disk of the case, and a viscous coupling filled with a highly viscous liquid is arranged inside the case, and the outer disk of the viscous coupling is inserted into the fixed case side. In a transfer for a four-wheel drive vehicle in which either one of the output shafts is mounted on the inner disc side and the other input/output shaft is mounted on the inner disc side, both of them are installed between the case of the viscous coupling and the shaft to which the inner disc is fixed. A transfer for a four-wheel drive vehicle, characterized in that a connection switching means for switching to a direct connection state is provided.