JPH0343860Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a power transmission device that enables switching of drive modes between two-wheel drive and four-wheel drive.

<Prior art> Four-wheel drive vehicles that transmit engine power to the front wheels and rear wheels are superior to vehicles that drive only the front wheels or only the rear wheels, and have superior traversal performance on roads with a small coefficient of friction, such as muddy terrain and snow. There is. However, in the case of direct-coupled four-wheel drive vehicles, where the power transmission system to the front wheels and the power transmission system to the rear wheels are directly connected, and the same amount of power is always transmitted to the front and rear wheels, when cornering, the front and rear wheels are connected directly. In addition, when driving straight at high speed on roads with a high coefficient of friction such as ordinary roads, there is a slight difference in the diameter of the tires, resulting in poor steering performance. There was a problem in that the difference in mileage could not be absorbed and unnecessary load was placed on the power transmission system.

Therefore, a so-called center differential type four-wheel drive vehicle has been developed, which transmits engine power to the front wheel power transmission system and the rear wheel power transmission system via a differential gear mechanism. In this case, the differential gear mechanism automatically creates a rotational difference between the front wheels and the rear wheels, thereby solving the problem described above.

By the way, when the engine is installed horizontally, the driving force transmission device is often a two-shaft type consisting of an input shaft and an output shaft that is connected to this via a transmission mechanism and is approximately parallel to the input shaft. has been done.
In the case of this transverse engine, the operating gear mechanism is provided with a differential gear mechanism with a planetary gear after final deceleration.

<Problems that the invention aims to solve> However, while center differential type four-wheel drive vehicles can solve the problems of direct-coupled type four-wheel drive vehicles, when driving on roads with a small coefficient of friction, the differential The problem was that the wheels tend to slip due to this action, resulting in inferior running performance compared to the direct-coupling type. In addition, four-wheel drive vehicles have the problem that because driving force is always applied to all wheels, there is a large power loss in the transmission system, resulting in poor fuel efficiency compared to vehicles with two-wheel drive in the front or two wheels in the rear. Furthermore, when the engine is horizontally mounted, a differential gear machine with a planetary gear is provided after the final deceleration, resulting in the problem that the device becomes larger and more complicated.

<Means for solving the problem> Therefore, the present invention connects an input shaft to the crankshaft of the engine, connects an intermediate shaft to the input shaft substantially parallel to it via a transmission mechanism, and connects a speed reduction mechanism to the intermediate shaft. The output shaft is connected substantially in parallel through the differential case, and the output shaft is connected to a differential case of a differential gear mechanism that compensates for the rotation speed between the front and rear wheels, and the front wheel side is connected to the first side gear of the side gear provided in the differential case. Alternatively, either one of the rotating shafts on the rear wheel side is connected, the second side gear is provided with a switching gear that can be switched between the first position and the second position, and the second side gear and the output shaft are connected to each other. A viscous clutch is provided between the two so that it can freely intervene between the two by switching the switching gear, and when the switching gear is set to the first position, the other of the front wheel side or rear wheel side rotating shaft is moved to the second position. At the same time, the differential case of the differential gear mechanism and the second side gear are connected via a viscous clutch, and when the switching gear is set to the second setting position, the second side gear and the second side gear are connected via a viscous clutch. The above-mentioned problem is solved by releasing the connection with the other rotating shaft and directly connecting the second side gear and the differential case without using the viscous clutch.

<Operation> According to the above means, since the intermediate shaft is interposed between the input shaft and the output shaft, the space of the entire transmission mechanism can be used effectively, so the power transmission device can be downsized, and the switching gear can be used as described above. This makes it possible to convert between two-wheel drive and four-wheel drive, and when driving in four-wheel drive, a viscous clutch exists between the front and rear wheels, and the action of this viscous clutch compensates for the difference in rotation between the front and rear wheels. On the other hand, if either the front or rear wheels slip and the relative rotational difference becomes large, the clutch action of the viscous clutch brings the front and rear wheels into a directly coupled state, improving all-terrain performance.

<Examples> Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of a viscous clutch and center differential according to an embodiment of the present invention, and FIG. 2 shows a schematic configuration of a power transmission system for a four-wheel drive vehicle incorporating the viscous clutch and center differential of FIG. 1.

In FIG. 2, 1 is an engine as a power source, and an input shaft 4 is connected to a crankshaft 2 of the engine 1 through a clutch mechanism 3 in a substantially straight line with the crankshaft 2. An intermediate shaft 6 is connected substantially parallel to the input shaft 4 via a mechanism (speed gear group) 5. An output shaft 8 is connected to the intermediate shaft 6 substantially parallel to the intermediate shaft 6 via a reduction gear 7 which is a reduction mechanism, and the output shaft 8 is connected to a front wheel 9 and a rear wheel 10.
A center differential 11, which is a differential gear mechanism, is provided to compensate for the rotational difference between the two. This center differential 11 includes a first axle 17 for driving the front wheels 9 and a rear wheel 1.
The first axle 17 is connected to a front differential 18 provided on the axle of the front wheel 9 via a final reduction gear 19, while the second axle 17 is connected to a front differential 18 provided on the axle of the front wheel 9. 21 is provided with a drive gear 22 that meshes with a reduction gear 23, and the reduction gear 23 is connected via a bevel gear to a propeller shaft 24 extending in the longitudinal direction of the vehicle. A rear differential 20 provided on the axle of the rear wheel 10 is connected.

Next, the center differential 11 where the first axle 17 and the second axle 21 are provided, and the center differential 11
The viscous clutch 30 provided adjacent to the viscous clutch 30 will be explained with reference to FIG. The power generated by the engine 1 is transmitted by the gear group described above and reaches the reduction gear 7. The reduction gear 7 meshes with an output shaft 8 through respective gears, and this output shaft 8 is connected to a bearing 2 on a support member 25 extending from the main body of the engine 1.
It is rotatably supported via 6. Output shaft 8
A differential case 12 of a center differential 11 is integrally fastened to one side with bolts 27, and a viscous clutch 30 is provided on the other side. The differential case 12 has a cylindrical shape with a cavity inside, and has a differential pinion 13 and a differential pinion 14 therein so as to be rotatable around the guide pins 31 and 32 and facing each other. Further, a second axle 21 is disposed inside the differential pinion 13 and the differential pinion 14 and is connected to the rear wheel 10 at right angles to the rotational direction of the differential case 12. The first axle 17 connected to the front wheel 9 is formed into a cylindrical shape, and is rotatably fitted to the outer periphery of the second axle 21, and a first side gear 15 is fixed to the end of the shaft. This first side gear 15 meshes with the pinion gear 13 and pinion gear 14.

On the other hand, the viscous clutch 30 has an outer cylinder 29 and an inner cylinder 31.
A space is defined by the and side walls, and this space is filled with viscous oil such as silicone oil, and the clutch plate 40 and the inner cylinder 31, which are implanted in the outer cylinder 29 and facing the inner cylinder 31, are filled in this viscous oil. Planted outer cylinder 29
Clutch plates 41 facing toward the front are arranged alternately. The outer cylinder 29 of the viscous clutch 30 is fitted onto the extending portion 8a of the output shaft 8 via the side plate 28, and thereby the outer cylinder 29 and the output shaft 8 are connected to rotate together. On the other hand, inner cylinder 3
1 is fitted with a tubular shaft body 32 by spline connection or the like, and the center differential 11 of this shaft body 32
The side shaft end is formed into a second side gear 16 that meshes with the pinion gear 13 and the pinion gear 14, and the other end is fixed with a gear adapter 34 that slidably supports the switching gear 33. installed. The second axle 21 passes through the inside of this shaft 32, and the shaft 32 is basically rotatable with respect to the second axle 21 and with respect to the output shaft 8. There is. The switching gear 33 supported by the gear adapter 34 is a gear that slides in the axial direction of the second axle 21 with its gear blades meshing with the gear adapter 34, and the outer cylinder 29 is attached to the outer periphery of the switching gear 33. An uneven portion is formed to fit into a protrusion such as a gear blade implanted on the inner surface of the holder. Furthermore, a fitting member 35 fixed to the shaft end of the second axle 21 is provided outward in the direction of movement of the switching gear 33, and this fitting member 35 has gear teeth on its outer periphery that mesh with the switching gear 33. There is. A wire or a lever (not shown) is connected to the switching gear 33.
These allow manual or automatic sliding along the gear blade of the gear adapter 34.

Next, the operation of the power transmission device having the above configuration will be explained.

Power generated by the engine 1 is transmitted from a crankshaft 2 and a clutch mechanism 3 to an input shaft 4, a transmission mechanism 5, an intermediate shaft 6, and a reduction gear 7 to a center differential 11. In the center differential 11, this power is transmitted to the front wheel 9 side via the first axle 17 by the differential pinion 13 etc., and is transmitted to the rear wheel 10 side by the shaft body 32.
, through the gear adapter 34 and the switching gear 33, and through the fitting member 35 of the second axle 21.
1. Rotation is then transmitted from the first axle 17 to the front differential 18 via the final reduction gear 19 to rotate the front wheels 9, while the second axle 21
Rotation is transmitted from the drive gear 22 to the propeller shaft 24 via the reduction gear 23, and the rear wheels 10 are rotated by the propeller shaft 24, respectively. And the front wheel 9 when cornering while driving, etc.
If a small relative rotational difference occurs between the rear wheel 10 and the rear wheel 10, the center differential 11 can compensate for the rotational difference. On the other hand, if either the front wheels 9 or the rear wheels 10 gets stuck in mud or the like with low frictional resistance, the wheels spin and the relative rotation difference between the front and rear wheels becomes large, that is, the rotation speed of the differential case 12 and the If a large difference is caused between the rotational speeds of the two axles 32, the clutch plate 40 installed in the outer cylinder 29 of the viscous clutch 30 and the clutch plate 41 installed in the inner cylinder 31 should be Due to the shear resistance of viscous oil,
To prevent the generation of a large rotational difference between the front wheels 9 and the rear wheels 10, and to prevent the wheel on one side from spinning in such a case.

From such four-wheel drive driving, the switching means operates manually or automatically by detecting the driving condition, etc.
When the switching gear 33 is moved to the second set position, that is, the position shown by the dashed line in the figure, the fitting member 35 provided on the second axle 21 is disengaged from the switching gear 33, and as a result, the second Axle 21 is engine 1
is separated from the power transmission means. At the same time, the switching gear 33 is connected to the viscous clutch 3 at its outer circumference.
0, the rotation speed of the shaft body 32 becomes equal to the rotation speed of the output shaft 8, and as a result, the pinion gear 13 etc. do not rotate, and the first axle 17 is directly connected to the output shaft 8. Rotate in the same position. That is, all of the power from the engine 1 is transmitted to the first axle 17, thereby setting the vehicle as a front two-wheel drive vehicle that runs on the front wheels 9. In this state, if the switching gear 33 is set to the first position shown by the protruding line, the vehicle can be set as a four-wheel drive vehicle again. Furthermore, since the device has a simple configuration, there is no risk of it becoming larger.

Incidentally, although the above embodiment is based on front wheel drive, the above embodiment is not limited to this and may be based on rear wheel drive.

In addition to the above embodiment, FIG. 3 shows a second embodiment in which the switching mechanism of the switching gear 50 is changed. In the second embodiment, the inner cylinder 31 of the viscous clutch 30 is fitted to the output shaft 8, and the first fitting member 51 is fitted integrally to the output shaft 8. A fitting member 35 provided on the second axle 21 is arranged parallel to the first fitting member 51. In the fitting portion provided on the inner periphery of the switching gear 50, the first fitting member 51 and the gear adapter 31 are coupled to each other at the second setting position shown by the solid line in the figure, and the first setting shown by the dashed line. At the position, the gear adapter 31 and the first fitting member 51 are coupled together. At the same time, at the outer periphery of the switching gear 50, the outer cylinder 29 of the viscous clutch 30 is
When the second set position is reached, the fitting is released and the outer cylinder 29 is left in a free state. Other constituent members are the same as those in the previous embodiment,
In the first setting position, the differential pinion 16 and the second axle 2
1 is connected, and the output shaft 8 and the second axle 21 are connected via the viscous clutch 30. At the second setting position, the second axle 21 is disconnected from the engine 1 side, and the output shaft 8 is connected to the second axle 21 via the viscous clutch 30. and differential pinion 16
Since the two wheels are directly connected to each other, the vehicle can be set as a four-wheel drive vehicle in the first setting position, and can be set as a two-wheel drive vehicle when switched to the second setting position. This can be achieved without requiring the side plate 28 of the clutch 30.

<Effects of the invention> As described above, the present invention has a switching mechanism that mutually converts the driving mode between two wheels and four wheels, so it can switch between four wheels arbitrarily or automatically depending on the driving situation. By converting from drive to two-wheel drive, it is possible to eliminate the deterioration in fuel efficiency that was a problem when using four-wheel drive.In addition, it can be used as a four-wheel drive vehicle with excellent drivability on snowy roads and muddy areas, and it also has low viscosity. Since it has a center differential with a clutch,
While maintaining high maneuverability during cornering, the advantages of a four-wheel drive vehicle can be fully utilized, and since the device uses space effectively, the overall device can be downsized and simplified.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a viscous clutch and differential mechanism according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a power transmission device including the viscous clutch and differential mechanism of FIG. 1, and FIG. FIG. 3 is a partial cross-sectional view showing another embodiment of the present invention. In the drawing, 1 is an engine, 2 is a crankshaft, 4 is an input shaft, 5 is a transmission mechanism, 6 is an intermediate shaft, 7 is a reduction gear, 8 is an output shaft, 9 is a front wheel, 10 is a rear wheel, 1
1 is a center differential, 12 is a differential case, 15 is a first side gear, 16 is a second side gear, 30
is a viscous clutch, and 33 is a switching gear.

Claims (1)

[Scope of utility model registration request] An input shaft is connected to the crankshaft of the engine, an intermediate shaft is connected approximately parallel to the input shaft via a transmission mechanism, an output shaft is connected approximately parallel to the intermediate shaft via a speed reduction mechanism, and the output shaft is connected to a differential case of a differential gear mechanism that compensates the rotation speed between the front and rear wheels, and either the front wheel side or the rear wheel side rotating shaft is connected to the first side gear of the side gears provided in the differential case. , the second side gear is provided with a switching gear capable of switching between a first position and a second position, and a viscous clutch is provided between the second side gear and the output shaft to switch between the two positions by switching the switching gear. When the switching gear is set to the first position, the other of the rotation shafts on the front wheel side or the rear wheel side is connected to the second side gear and the differential case of the differential gear mechanism. The second side gear is in a connected state via the viscous clutch, and when the switching gear is set to the second setting position, the connection between the second side gear and the other rotating shaft is released, and A power transmission device with a two-wheel/four-wheel drive mode switching mechanism, characterized in that the side gear and the differential case are directly coupled without using the viscous clutch.