JPS63112220A - Transfer structure of four-wheel drive car - Google Patents

Abstract

PURPOSE:To improve durability of an actuation limit device, by a method wherein a transfer device is provided with a means for switching wheels between a 4-wheel drive state in that the actuating motion of a center diff and the actuation limit motion of an actuation limit device are performed and a 4-wheel drive state in that the center diff is completely locked. CONSTITUTION:When a sleeve 44 of a switching mechanism mounted to a transfer device 3 intercouples spline members 41-43, a center diff 20 is brought into a locked state to integrally rotate a sun gear 21 and a ring gear 25. Differential motion by means of the center diff 20 is blocked, a power from an engine is outputted to front and rear wheels on both sides in a state to also block relation rotation of outer and inner cases 31 and 32 of a viscous coupling 30, and wheels are brought into a complete locked 4-wheel drive state. Meanwhile, when the sleeve 44 intercouples only first and second splines 42 and 43, a power transmitted through a transfer shaft 8 to the second spline member 42 is outputted only to the rear wheel side and the wheels are brought into a 2-wheel drive state.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a transfer structure for a four-wheel drive vehicle, and particularly to a four-wheel drive vehicle that is equipped with a center differential that divides power from a transmission into a bamboo wheel side and a rear wheel side, The present invention relates to a transfer structure for a four-wheel drive vehicle that enables good control of operation.

(Prior art) The power output from the engine via the transmission is divided to drive the front wheels and rear wheels, respectively.4
Wheel drive vehicles are sometimes equipped with a center differential to eliminate the so-called braking phenomenon during cornering. This center differential consists of an input element into which power is input from the engine or transmission, and output elements for front wheels and rear wheels that divide the power input into the element and transmit it to the front wheels and rear wheels, respectively. By performing differential operation between the output elements, the difference in rotational speed between the front and the front wheels during cornering is absorbed.

By the way, when a four-wheel drive vehicle is equipped with a center differential as described above, a problem arises in that when one of the front wheels or the rear wheels slips, power is not transmitted to the other wheel. Therefore, for example, according to Japanese Utility Model Application Laid-Open No. 60-127232@, a switching mechanism is provided in this type of transfer device, and the operation of the mechanism switches between a four-wheel drive state in which differential operation is performed by the center differential and a four-wheel drive state in which differential operation is performed by the center differential. A four-wheel drive state in which differential operation is inhibited is performed. According to this, it is possible to select whether or not to perform differential operation by the center differential depending on the driving condition of the VJ vehicle, and therefore, when slipping as described above occurs, the differential operation can be prevented. By transmitting power equally to the front and rear wheels, the vehicle can be brought out of a slipping state.

(Problems to be Solved by the Invention) However, the system disclosed in the above publication switches the center differential between either a completely free state or a completely locked state, so it is difficult for the vehicle to It is not possible to automatically control the differential operation of the center differential depending on the driving condition. Therefore, for example, if you neglect to unlock the center differential, a braking phenomenon will occur when cornering, and conversely, if you leave the center differential free, the driving condition will become unstable, especially during sharp cornering, or the front or rear wheels will If either one of them slips, problems arise such as the vehicle being unable to start or the required starting acceleration being unable to be achieved.

The present invention addresses the above-mentioned problems in four-wheel drive vehicles equipped with a center differential, and the present invention automatically controls the differential operation of the center differential depending on the driving condition, or completely blocks the differential operation. The purpose is to realize a transfer device that can

(Means for Solving the Problems) A transfer structure for a four-wheel drive vehicle according to the present invention is characterized in that it is configured as follows to achieve the above object.

That is, in a transfer structure that transmits the output of a transmission into which power is input from the engine to the front wheels and rear wheels, there is a center differential that transmits the power output from the transmission to the front wheels and the rear wheels; and a differential limiting device that limits the differential operation of the center differential when the rotational speed difference between the wheels is greater than or equal to a predetermined width, and the differential operation by the center differential and the differential limiting operation by the differential limiting device are performed. The present invention is characterized in that a switching means is provided for switching between a four-wheel drive state in which the vehicle is operated and a four-wheel drive state in which differential operation by the center differential is inhibited.

(Function) According to the above configuration, since the transfer device having the center differential is equipped with a differential limiting device such as a viscous coupling, cornering with a relatively small rotational speed difference between the front and rear wheels is possible. At times, the differential limiting device allows for differential operation of the center differential, thereby enabling smooth cornering. On the other hand, if the difference in rotational speed between the front and rear wheels increases beyond a predetermined limit, such as when either the front or rear wheels slip during sharp cornering or sudden start, , by the differential limiting device limiting the differential operation of the center differential,
Driving stability and starting performance during sharp cornering will be improved.

Furthermore, due to the operation of the switching mechanism, the center differential is completely locked and differential operation is prevented from the four-wheel drive state in which both the differential operation by the center differential and the differential limiting operation by the differential limiting device are performed as described above. By switching to the 4-wheel drive state, it goes without saying that the driving stability during sharp cornering is improved, but also when driving on rough roads for a long time, etc. This prevents a decrease in the durability of the differential limiting device due to frequent limiting operations.

(Example) Examples of the present invention will be described below.

First, the overall configuration of the four-wheel drive vehicle according to this embodiment will be explained with reference to FIG. is installed. In that case, the output shaft 4 of the engine 1, the input shaft 6 and output shaft 7 of the transmission 2 connected to the engine output shaft 4 via the clutch 5, and the transmission output shaft 6
The transfer shaft 8 of the transfer device 3 connected to the transfer shaft 8 is arranged so as to extend in the longitudinal direction of the vehicle body.

On the other hand, the transfer device 3 divides and outputs the power input from the transmission 2, drives the front wheels 12, 12 via the front propeller shaft 9, the front wheel differential 10, and the front axle 11, and Wheel side propeller shaft 13,
Rear wheel 16.1 via contact wheel differential 14 and rear axle 15
6.

Next, the structure of the transfer device 3, which is a characteristic part of the present invention, will be explained based on FIG. A viscous coupling 30 and a switching mechanism 40 for switching the driving state of the vehicle are provided.

The center differential 20 includes a sun gear 21 and a plurality of pinion gears 22 disposed around the gear 21 and meshing therewith.
. . 22, a carrier 24 that supports these pinion gears 22 . . . 22 via pinion shafts 23 . It consists of 25.

Further, the viscous coupling 30 has an outer case 31, an inner case 32, and both cases 31 and 32.
It has a large number of plates 33...33 arranged between them and engaged with them alternately, and each plate 33...
33 is filled with viscous fluid.

Further, the switching mechanism 40 includes first to third spline members 41 to 43 each having a spline having the same specifications at its tip.
and a sleeve 44 that is slidably fitted across the splines of these members 41 to 43.

However, in this transfer system @3, the power transmission path from the transfer shaft 8 to the front propeller shaft 9 and the rear propeller shaft 13 via the switching mechanism 40 is as follows.
The configuration is as shown below.

That is, the carrier 24 of the center differential 20 is connected to the transformer 77 shaft 8, and the rear wheel output shaft 52, which is fixed to the ring gear 25 of the center differential 20 via the drum 51, is connected to the rear wheel side. A propeller shaft 13 is connected. Further, the first spline member 4 of the switching mechanism 40
1 is integrally formed with an intermediate gear 53 that is rotatably supported on the transfer shaft 8, and a front wheel output gear 54 is meshed with the gear 53.
The front wheel propeller shaft 9 is connected to the front wheel output shaft 55 to which the front wheel propeller shaft 9 is fixedly attached. Furthermore, the outer case 31 of the viscous coupling 30 and the ring gear 25 of the center differential 20 are connected to the third spline member 43 of the switching mechanism 40, and these are connected to the transfer shaft 8 and the inner case 32 of the coupling 30. It is rotatably supported. Further, the second spline member 42 in the switching mechanism 40 includes the coupling 30.
The inner case 32 and the sun gear 21 of the center differential 20 are connected, and these are also rotatably supported on the shaft 8 of the transformer 77.

When the sleeve 44 of the switching mechanism 40 is in the illustrated position, the first to third
The spline members 41 to 43 are all connected, and if the upper two sleeves 44 are slid to the left, the first
．． Only the second spline members 41 and 42 are connected, and if the sleeve 44 is further slid to the right, the second spline member 41,42 is connected. Only the third spline members 42, 43 are connected.

Next, the operation of this embodiment will be described. Power outputted from the engine 1 via the clutch 5 and the transmission 2 is inputted from the output shaft 7 of the transmission 2 to the transfer shaft 8 of the transfer device 3. When the sleeve 44 of the switching mechanism 40 in the transfer device 3 is held in the illustrated position and the first to third spline members 41 to 43 are all connected via the sleeve 44, the center differential 20 is In the locked state, the ring gear 21 and the ring gear 25 rotate together. Therefore, the differential operation by the center differential 20 is prevented, and the relative rotation between the outer case 31 and the inner case 32 of the viscous coupling 30 is also prevented, and the power is output to the front wheels and the rear wheels. . That is, the power input to the transfer shaft 8 is transmitted from the carrier 24 of the center differential 20 in the locked state to the second spline member 42 of the switching mechanism 40 via the sun gear 21, etc. It is output from the spline member 41 to the front wheel output shaft 55 via the intermediate gear 53 and the front wheel output key V54, and for the rear wheel side, it is output from the third spline member 43 to the rear wheel output shaft 52 via the drum 51 etc. It is.

The power output to the front wheel output shaft 55 is transmitted to the front wheels 12.12 via the front wheel propeller shaft 9, the front wheel differential 10, and the front axle 11, and is also output to the rear wheel output shaft 52. The generated power is transmitted to the rear wheels 16, 16 via the rear propeller shaft 13, the rear wheel differential 14, and the rear shaft 15, thereby putting the vehicle in a so-called fully locked four-wheel drive state.

Also, the sleeve 44 in the switching mechanism 40 is slid to the right from the illustrated position to the second position. When only the third spline members 42 and 43 are connected via the sleeve 44, the center differential 20 is in the locked state and the power transmitted from the transfer shaft 8 to the second spline member 42 is It is output only to the rear wheel side via the same route as in the above case. As a result, the vehicle has rear wheels 1
6. The vehicle enters a two-wheel drive state in which only the 16th wheel is the driving wheel.

Further, the sleeve 44 in the switching mechanism 40 is slid to the left from the illustrated position to the first position. When only the second spline members 41 and 42 are connected via the sleeve 44, power is input from the transfer shaft 8 to the gear shaft A724 of the center differential 20, and then the sun gear 21 and ring gear 25 are connected. divided into a predetermined distribution ratio.

Then, the power divided to the sun gear 21 side is transmitted to the first gear. The power is transmitted to the intermediate gear 53 via the second spline member 41, 42, and further output to the front wheel output shaft 55 via the face width output gear 54, and the power is divided to the ring gear 25 side. It is output to the rear wheel output shaft 52 via.

In this case, the viscous coupling 30 has an inner case 32 in the middle of the power transmission path to the front wheels and an outer case 31 in the middle of the power transmission path to the rear wheels.
The following operations are performed depending on the driving state of the vehicle. In other words, during relatively gentle cornering,
The coupling 30 is connected to the center differential 20.
Relative rotation between 21 and ring gear 25 (differential operation)
Therefore, the difference in rotational speed due to cornering between the bamboo wheels 12.12 and the rear wheels 16.16, which are respectively interlocked with the gears 21.25, is absorbed, and the bragging phenomenon is eliminated. On the other hand, when the rotational speed difference between the front and rear wheels exceeds a predetermined amount, such as during sharp cornering or when either the front wheel 12.12 or the rear wheel 16.16 slips, viscous coupling 30
limits the differential operation of the center differential 20 on the sun gear 21 and ring gear 25 sides, so that the center differential 20 approaches the locked state and the rotational speed difference between the front and rear wheels as described above is eliminated or suppressed. become. Therefore, during sharp cornering, it is possible to prevent the running condition from becoming unstable due to an excessive difference in rotational speed between the front and rear wheels.
When either one of 16 slips, power is transmitted to the other, making it possible, for example, to escape from the slip state or to obtain the required starting acceleration. In this way, in the four-wheel drive state in which the differential operation by the center differential 20 and the differential limiting operation by the viscous coupling 30 are performed, the differential operation by the center differential 20 is controlled to suit the driving condition. become.

As described above, the operation of the switching mechanism 40 allows a four-wheel drive state in which the center differential 20 is completely locked, a two-wheel drive state in which only the rear wheels are the driving wheels, and a two-wheel drive state in which the center differential 20 is completely locked.
Driving performance is improved by switching between a four-wheel drive state in which both the differential operation by the viscous coupling 30 and the differential limiting operation by the viscous coupling 30 are performed according to the driving condition. Furthermore, by being able to select one of the two types of four-wheel drive states, for example, both the center differential 20 and the viscous coupling 30 operate.
When driving on a rough road or snowy road for a long period of time in a wheel drive state, the differential limiting operation by the coupling 30 is frequently performed, and the coupling 30 may generate heat or its durability may deteriorate. This will avoid a situation where the amount of energy decreases.

Furthermore, in this embodiment, since the center differential 20 and the viscous coupling 30 are both arranged on the transfer shaft 8, the structure of the power transmission path and the structure of the switching mechanism between the two are simplified, and This means that the device 3 can be made more compact.

Incidentally, the switching mechanism in this embodiment may not be constructed as described above, but may be constructed using a hydraulically operated multi-disc friction clutch as shown in FIG. In other words, as shown in the figure, this switching mechanism 40 has a plurality of friction plates arranged between the left end of the drum 61 connected to the sun gear 21 of the center differential 20 and the hub 62 integrated with the intermediate gear 53. A plurality of IIJ! A second clutch 65 is provided with a ta plate, and both clutches 63
．． 65 is adapted to transmit power or cut off transmission of power by supplying and discharging hydraulic oil, respectively. And the first. When both the second clutches 63 and 65 are in the power transmission state, the center differential 20 is completely locked, resulting in a four-wheel drive state, and when only the second clutch 65 is in the power transmission state, the rear wheel In a two-wheel drive state in which only the first clutch 63 is the driving wheel, and only the first clutch 63 is in a power transmission state, the center differential 20 operates and the suspension coupling 30 performs an operation limiting operation.
It becomes a wheel drive state.

FIG. 4 shows a second embodiment of the present invention, in which an output shaft 70 of a transmission, left and right front wheel drive shafts 71, 72, and an intermediate shaft 73 are arranged in the width direction of the vehicle body. ing. Then, the left and right front wheel drive shafts 7
A front wheel differential 80 is provided around the opposite end of the opening drive shaft 71 .
72, a differential case 81 rotatably supported on the case 81, a pinion shaft 82 installed on the case 81, and a pair of pinion gears 8 rotatably supported on the shaft 82.
3.84, and a pair of left and right output gears 85.86 meshed with both pinion gears 83.
18Il is extensively bound.

On the other hand, this transfer device 3a is equipped with a center differential 20a consisting of a double planetary gear mechanism and a viscous coupling 30a, as well as a switching mechanism 408.
The first spline member 41a is connected to the ring gear 25a of the center differential 20a, and the second spline member 42a is connected to the rear 24a of the center differential 20a and the viscous coupling 30.
A third spline member 43 is attached to the inner case 32a of
a are connected to the differential case 81, respectively. Further, the zangki r21a of the center differential 20a and the outer case 31a of the viscous coupling 30a are connected, and a first width gear r74 is fixed to the connection part, and the intermediate shaft 73 is provided with the first intermediate gear r74. A second intermediate gear 75 that meshes with the gear 74 and a rear wheel output gear 78 that meshes with a gear 77 fixed to a rear wheel output shaft 76 are integrally formed.

When the sleeve 44a of the switching mechanism 408 is in the illustrated position, the power input from the output gear 79 of the transmission to the ring gear r25a of the center differential 20a is transmitted to the front wheel side, the rear wheel side, that is, the differential case 81, and the first gear. However, in this case, a four-wheel drive state is established in which the differential operation of the center differential 20a is inhibited.

Furthermore, when the sleeve 44a is slid to the left from the illustrated position, the center differential 20a is locked and the power input to the ring gear 25a is transmitted only to the rear wheels. This results in a two-wheel drive state in which only the rear wheels are the driving wheels.

Further, when the sleeve 44a is slid to the right from the illustrated position, the power input to the ring gear 25a is distributed between the ring gear 21a side and the carrier 2 at a predetermined distribution ratio.
It is divided into 4a side and 4a side. As a result, the vehicle has a differential operation by the center differential 20a and a viscous coupling 3.
A four-wheel drive state is established in which a differential limiting operation of 0a is performed.

In this manner, also in this embodiment, the vehicle is switched between a fully locked four-wheel drive state and a four-wheel drive state in which the differential operation of the center differential 20a is automatically controlled according to the driving condition. Therefore, running performance is improved and a decrease in durability of the viscous coupling 30a is effectively prevented.

FIG. 5 shows a third embodiment of the present invention, and a transfer device 3b according to this embodiment also includes a center differential 20b and a viscous coupling 30b, which are made of a double binion type brane gear V mechanism, as in the second embodiment. It is disposed on the front wheel drive shaft 7Ib, and the center differential 2
0b is connected to the third spline member 43b of the switching mechanism 40tl via the outer case 31b of the coupling 30b, and the sun gear 21b is connected to the second spline member 42b of the switching mechanism 40b via the inner case 32b of the coupling 30b. A differential case 81b of a front wheel drive device 80b is connected to a first spline member 41b of a switching mechanism 40b. The carrier 24b of the center differential 20b and the viscous coupling 30b
A first intermediate gear A' is connected to the outer case 31b.
74b is fixed, and the second intermediate gear 75b on the intermediate shaft 73b, the rear wheel output gear 78b, the front wheel shaft 76b, etc. have the same structure as in the second embodiment.

Therefore, the sleeve 44b in the switching mechanism 401)
When the sleeve 44b is in the illustrated position, a four-wheel drive state is established in which the differential operation by the center differential 20b is blocked, and when the sleeve 44b is slid to the right from the illustrated position, only the rear wheels become the driving wheels. A wheel drive state is entered, and when the sleeve 44b is further slid to the left from the illustrated position, a four-wheel drive state is entered in which differential operation by the center differential 20b and differential limiting action by the viscous coupling 30b are performed. By appropriately performing such a switching operation, the running performance is improved and the durability of the viscous coupling 30b is improved.

FIG. 6 shows a fourth embodiment of the present invention. In this embodiment, a trans hood neck 3C has a center differential 20c consisting of a single binion type planetary gear mechanism and a viscous coupling 30C on the left front wheel drive @71C. and the output gear 79c of the transmission.
The power from the carrier 24c is inputted via the carrier 24c. The ring gear 25c of the center differential 20c is connected to the outer case 3 of the viscous coupling 30c.
1c to the third spline member 43 of the switching mechanism 40G.
0, the sun gear 21C is connected to the second spline member 42c of the switching mechanism 30b via the inner case 320 of the viscous coupling 30c, and the differential case 81C of the front wheel differential 80c is connected to the first spline member 41c.
The transfer device 3b of the third embodiment is similar to the transfer device 3b of the third embodiment in that the transfer device 3b is interconnected and that the first intermediate gear 740, the second intermediate gear 750, etc. are provided.

Accordingly, °C1 Also in this embodiment, by changing the driving state of the vehicle through the operation of the switching mechanism 400,
Good running properties are obtained, and the durability of the viscous coupling 30c is improved.

(Effects of the Invention) As described above, according to the present invention, a transfer device for a four-wheel drive vehicle includes a center differential and a differential limiting device, and the transfer device includes a differential operation by the center differential and a differential limiting device. Since a switching means is provided to switch between a four-wheel drive state in which differential limiting operation is performed and a four-wheel drive state in which the center differential is completely locked, not only good running performance is ensured, but also the differential This prevents deterioration in the durability of the limiting device due to frequent limiting operations of the limiting device.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, and FIG. 1 is a schematic diagram showing the overall configuration of a four-wheel drive vehicle according to the embodiment;
FIG. 2 is a schematic diagram showing the main part thereof, that is, the transfer device, and FIG. 3 is a schematic diagram showing the transfer device with a different switching mechanism. Also, 4th. Fifth. FIG. 6 shows the second and third parts of the present invention, respectively.
．． FIG. 7 is a schematic diagram of a transfer device showing a fourth embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 2... Transmission, 3°3a, 3b, 3c... Transfer device, 12.
・・Front wheel, 16・ff1 wheel, 20.20a, 20b
. 20 c-...center differential, 30.30a, 30b
. 300...Differential limited bag @ (viscous coupling)
, 4.0. /IOa, 40b, 40c -...Switching means (switching mechanism). Figure 2, Figure 4, Sn, Figure 5, Figure 6, and

Claims (1)

[Claims] (1) A transfer structure for a four-wheel drive vehicle that transmits the output of a transmission into which power is input from the engine to the front wheels and rear wheels, wherein the power output from the transmission is transmitted to the front wheels and the rear wheels. and a differential limiting device that limits the differential operation of the center differential when the rotational speed difference between the front and rear wheels is greater than or equal to a predetermined amount. A four-wheel drive vehicle characterized by being provided with a switching means for switching between a four-wheel drive state in which a differential limiting operation by a limiting device is performed and a four-wheel drive state in which differential action by the center differential is blocked. transfer structure.