JPH0292728A - Device for distributing power of four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To lower a vibration noise by installing one wet hydraulic multiple disk clutch between the output shaft of an automatic transmission integrally formed with a transfer and a transfer gear while providing the other wet hydraulic multiple disk clutch in an independent differential device behind a propeller shaft. CONSTITUTION:Power taken out of an engine 1 to an output shaft 9 via an automatic transmission 4 is inputted into a front-wheel differential device 3 via a first wet hydraulic multiple disk clutch 7, a front drive shaft 11, etc. to be transmitted to right/left front wheels therefrom. On the other hand, power taken out of the output shaft 9 to the rear of a transfer device 5 is inputted into a rear-wheel differential device 8 via a propeller shaft 6, a second wet hydraulic multiple disk clutch 28, etc. to be transmitted to right/left rear wheels therefrom. A control system is formed by providing a switch group for selecting the traveling modes of an FF traveling in which only the multiple disk clutch 7 is engaged, an FR traveling in which only the multiple disk clutch 28 is engaged, and a 4WD traveling in which both multiple disk clutches 7, 28 are engaged.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a power distribution device for a four-wheel drive vehicle equipped with a wet hydraulic multi-plate clutch that distributes power to front and rear wheels.

[Conventional technology]

As a power distribution device for such four-wheel drive vehicles,
The one described in Japanese Patent No. 1-1.55027 is conventionally known. This is a system in which two wet hydraulic multi-disc clutches, one for front wheel drive and one for rear wheel drive, are placed inside the case of a transfer device that branches and transmits power from the transmission output shaft to the front and rear wheels. It is possible to continuously distribute power to the front and rear wheels at any ratio depending on the situation. In these wet hydraulic multi-disc clutches, the working oil is shared with the lubricating oil for gears and bearings in the transfer device.

[Problem to be solved by the invention]

In this way, the hydraulic oil of the wet hydraulic multi-disc clutch is shared with the lubricating oil exclusively used for gears, so it is possible to obtain appropriate frictional characteristics when the vehicle is turned in four-wheel drive and slipping occurs due to large steering changes. As a result, the friction torque is unstable, causing stick-slip and vibration noise. Furthermore, since the transfer device accommodates two wet-type hydraulic multi-disc clutches and becomes elongated, its rigidity decreases, increasing vibration and noise in the drive system, or reducing the space inside the vehicle. Therefore, the present invention makes it possible to set the torque distribution to the front and rear wheels at any ratio while having a compact device configuration on the transfer side, and prevents the occurrence of stick-slip when the wet hydraulic multi-disc clutch slips. At the same time, the handling stability of the vehicle. Our goal is to maximize starting performance and turning performance, and to fully respond to the driver's driving preferences.

[Means to solve the problem]

For this purpose, the present invention provides a four-wheel drive vehicle that is configured to transmit power between the front and rear wheels by changing the pressure of hydraulic oil to two wet hydraulic multi-disc clutches depending on the driving condition.
One of the above wet-type hydraulic multi-disc clutches is interposed between the output shaft of the vertical transaxle automatic transmission mechanism integrated with the transfer and the transfer gear for driving the drive pinion. is divided into an independent differential device after the propeller shaft and interposed in the middle of the transmission shaft, and the control system of both wet hydraulic multi-disc clutches includes one wet hydraulic multi-disc clutch connected to the front wheels. FF driving mode that only transmits power to the rear wheels, FR driving mode that transmits power only to the rear wheels via the other wet hydraulic multi-disc clutch, and 4WD mode that transmits power to the front and rear wheels via both wet hydraulic multi-disc clutches.
It is equipped with a switch group that allows selection of each driving mode.

[Function] With such means, power is distributed to the front and rear wheels at a desired ratio by hydraulically controlling each wet hydraulic multi-plate clutch. Here, the other or both wet hydraulic multi-disc clutches can obtain the desired friction characteristics by using an appropriate hydraulic oil with a predetermined composition, and when internal circulation torque is generated between the front and rear wheels or between the four wheels. When turning the wheel significantly in the driving state, the clutch play 1 smoothly slides without stick-slip. The FF is then controlled by each wet hydraulic multi-disc clutch according to the operation of the switch group. The driver can select between FR and controlled 4WD driving modes that can distribute power between the front and rear wheels. [Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings. FIG. 2 shows the power transmission system of a four-wheel drive vehicle equipped with an RR-based transfer and an integrated vertical transaxle automatic transmission to which one embodiment is applied, with an engine installed at the front of the vehicle. Torque converter 2. Front wheel differential 3. Automatic transmission 4. A transfer device 5 is integrally arranged vertically in the front-rear direction, and a rear wheel differential device 8 is arranged at the rear of the vehicle body via a propeller shaft 6. Then, power is manually applied from the engine 1 to an automatic transmission 4 that changes gears by switching friction elements using hydraulic pressure controlled by a hydraulic control device via a torque converter 2.
The gears are shifted from the transmission output shaft 9 to the first wet hydraulic multi-plate clutch 7, the transfer drive and driven gears lOa, tOb, the front drive shaft H, the drive pinion 12. The power is manually applied to the front wheel differential device 3 via the final gear 13, and the power is transmitted from there to the left and right front wheels. Further, the power taken out from the transmission output shaft 9 to the rear of the transfer device 5 is transferred to the propeller shaft 6, the second wet pressure multi-plate clutch 28. The power is input to the rear wheel differential device 8 via the final gear 2■, and the power is transmitted from there to the left and right rear wheels. Here, the above-mentioned 1. Second two wet hydraulic multi-disc clutches 7
．． 28, as shown in FIG. 3, an oil pump 14a in the transaxle automatic transmission 4 that is directly driven by the engine, an oil pump 14b that is driven by an electric motor, and regulator valves 15a, 1.
5b,) Lancer Facility Rubber 18a16
b, duty solenoid valve 17a, 171)
A hydraulic control system dedicated to power distribution that includes pilot valves 18a and 18b provides appropriate control hydraulic pressure according to the driving condition. They are now being paid. These hydraulic control systems have approximately the same configuration, so to explain one of them, the hydraulic circuit from the oil pump 14a to the automatic transmission river surface pressure control device is branched, and the pressure is regulated to a predetermined hydraulic pressure by the regulator valve 15a. A transfer clutch valve LEA for controlling duty pressure is interposed in the hydraulic circuit system leading to the hydraulic multi-disc clutch 7, and a duty solenoid valve 17a for discharge control is provided in the pilot pressure circuit system having a pyro-soton valve 182. has been inserted. Then, the duty solenoid valves 1.7a and 17b in both hydraulic control systems are adjusted to the desired duty pressures using the duty signals from the control unit (control unit) 9, respectively, so that the transfer valve solenoid valve 18
a and 16b are individually adjusted to desired clutch pressures. The relationship between the duty ratio, duty pressure, and clutch pressure is shown in FIG. 4. The first wet hydraulic multi-disc clutch 7 equipped with such a hydraulic control system is disposed within the transfer device 5 at the rear end of a vertical transaxle integrated with the transfer, as shown in FIG. 1(a). . That is, the transfer drive gear IOa is rotatably fitted to the boss portion 9a of the transmission output shaft 9 facing into the transfer device 5 via a needle bearing 22, and is rotatably fitted to the transmission case 24 via a bearing 23. The first wet hydraulic multi-disc clutch 7 is interposed between the transfer drive gear lOa and the boss portion 9a. Here, below the transmission output shaft 9, the transfer drive gear 1. A transfer driven gear lOb that meshes with Oa is fixed by spline fitting, and a drive pinion 12 that meshes with the final gear 13 is integrally formed at the front end!・Drive shaft 11
is rotatably supported and arranged parallel to the transmission output shaft 9, and the power from the transmission output shaft 9 is transmitted to the left and right front wheels via the first wet hydraulic multi-disc clutch 7 as described above. communicated. Now, in the first wet hydraulic multi-disc clutch 7, the clutch drum 7a is fitted and fixed to the boss portion 9a of the transmission output shaft 9 by welding or the like, and the clutch hub 7b is similarly welded and fixed to the side part of the transfer drive gear lOa. has been done. On the inner periphery of the clutch drum 7a, a plurality of ring-shaped clutch plates 7C are arranged at both ends of the retainer brakes 1-7d, 7.
spline fitting with h, - one side 5 clutch hub 7b
A plurality of ring-shaped clutch disks 7C are arranged alternately with the clutch plates 7C and are spline-fitted on the outer periphery of the clutch plate 7C, and these clutch plates 7c, retainer brakes 7d, and 7b clutch disks 7e constitute a multi-plate clutch. has been done. The piston 7r that comes into contact with such a multi-disc clutch to apply a pressing force is connected to the boss portion 9a1. : 1 slidably via the seal ring 25a
A hydraulic chamber 7g is formed between the clutch drum 7a and the transfer clutch valve 16a by slidingly contacting the outer periphery of the clutch drum 7a with the inner periphery of the clutch drum 7a via a seal ring 25b. Ru. Also, on the opposite side of the hydraulic chamber 7g, a return spring 27 is supported by a retainer ring 26 and biased to push back the piston 7'' when the hydraulic pressure in the hydraulic chamber 7g is released.Here, the retainer ring 26 , is fitted onto the boss portion 9a of the transmission output shaft 9, and its axial movement is restricted by a snap ring 38, and its outer circumferential portion is connected to the cup-shaped inner circumferential surface of the piston 7'' via a seal ring 39. By slidingly contacting the piston 7r, a centrifugal hydraulic chamber 42 is formed which communicates with the oil passage 4I via the check valve 40. On the other hand, the second wet hydraulic multi-disc clutch 28, together with its hydraulic control system, As shown in Figure (b), the differential carrier 29 is a case member of the rear wheel differential 8. The differential carrier 29 includes the drive pinion 30 and propeller of the rear wheel differential 8. A cylinder part 33 that protrudes forward so as to cover the loose fitting part with the input shaft 31 on the shaft 6 side and connects to the extension case 32 around the input shaft 31 is integrally formed as a fixed member, and as shown in FIG. As shown, a valve unit 20 integrally comprising the valves t5b, teb, t'yb, and tab is fixed to the lower surface of the cylinder portion 33, and an electric oil pump 14b is fixed to the side surface of the cylinder portion 33. A second wet-type hydraulic multi-disc clutch 28 is disposed inside. Here, in the second wet-type hydraulic multi-disc clutch 28, a clutch drum 28a is welded and fixed to a flange portion 31a at the rear end of the input shaft 31. At the same time, the clutch hub 28b is spline-fitted to the shaft portion 30a of the drive pinion 30 and is locked to the end of the input shaft 31 via a thrust washer 34.A plurality of disks are arranged on the inner periphery of the clutch drum 28a. A ring-shaped clutch plate 28c is spline-fitted with the retainer plates 28d at both ends, while a plurality of ring-shaped clutch discs 280 are arranged alternately with the clutch plates 28c on the outer periphery of the clutch hub 28b and are spline-fitted with the retainer plates 28d at both ends. Together, the clutch plate 28C, the retainer plate 28d, and the clutch disc 280 constitute a multi-disc clutch.The ring-shaped piston 28f' that applies a pressing force to the retainer plate 28d is connected to the fixed member. Cylinder part 3
3 to form a hydraulic chamber 28g communicating with the transfer clutch valve 16b between the partition wall 33a and the inner guide cylinder 33b, and an operating end opposite to the hydraulic chamber 28g. The retainer plate 28d contacts the retainer plate 28d via the release bearing 35 of angular contact. In the release bearing 35, the outer race 35a that contacts the piston 28r engages with the inner guide cylinder 33b in the rotational direction via the claw 351), and the inner race 35
The piston 28r is spline-fitted to the inner periphery of the clutch drum 28a, and the piston 28r is prevented from rotating relative to the cylinder portion 33 by restricting rotation of the outer race 35a. On the other hand, the input shaft 31 and the shaft portion 3 of the drive pinion 30
Oil passages 31b and 3 are provided at 0a so as to communicate between the outer circumferential side of the clutch drum 28a and the inner circumferential side of the clutch hub 28t).
0b is formed. Then, the hydraulic oil in the cylinder portion 33 is scraped up by the outer periphery of the clutch drum 28a and supplied to the oil passage 30b by an oil guide (not shown), and this hydraulic oil is supplied to the oil passage 3! l) to the inner circumferential side of the clutch hub 28I), thereby lubricating the multi-disc clutches such as the clutch plate 28C and the clutch disc 28e through oil passages (not shown) provided in the radial direction in the spline portion. ing. In order to prevent this hydraulic oil from leaking, oil seals 3B and 3 are provided at the inner circumference of the partition wall 33a of the cylinder portion 33 and the inner circumference of the front part of the extension case 32, respectively.
7 is installed. Furthermore, since the hypoid gear lubricating oil and the hydraulic oil in the differential have different characteristics, the partition wall 3
The oil seals 36 on the inner periphery of the oil seals 3a are configured to maintain liquid tightness with each other. The control unit 19 generates a throttle opening signal. The driving condition of the vehicle is constantly judged by inputting various signals such as rear wheel rotation signal, front wheel rotation signal, range signal, and idle signal, and the optimal one is determined from a preset table map using throttle opening and vehicle speed as parameters. The duty ratio signal is transmitted to each of the duty solenoid valves 17a,
17b, the first and second wet hydraulic multi-disc clutches 7
．． 28 clutch pressures are controlled. Here, the control unit 19 receives an FF travel command signal from the FF switch 43a and an FR drive command signal from the FR switch 431).
A driving command signal and a 4WD driving command signal capable of distributing power between the front and rear wheels from the control 4WD switch 43c are respectively input. This control unit).19 controls one of the duty solenoid valves 17 based on the FF travel command signal.
A 0% duty ratio signal is output only to the FR travel command signal, and a 0% duty ratio signal is output only to the other duty solenoid valve 17b based on the FR travel command signal, and power can be distributed between the front and rear wheels. Based on the 4WD driving command signal, both duty solenoid valves 17a, 17
Duty ratio signals ranging from 0% to 100% are output from the table map roughly set in b. In the four-wheel drive vehicle having the above configuration, the power transmitted from the engine 1 to the automatic transmission 4 via the torque converter 2 is appropriately shifted there, and the power is transferred from the transmission output shaft 9 to the first wet hydraulic Four-wheel drive is achieved by manually applying power to the front wheel differential 3 via the multi-disc clutch 7, and manually applying power to the rear wheel differential 8 via the second wet hydraulic multi-disc clutch 28. In this case, power is distributed to the front wheels and the rear wheels according to the transmission torque of each wet hydraulic multi-plate clutch 7.28. This distribution ratio is adjusted to 100% for the front wheels by changing the clutch pressure according to the duty ratio signal from the control unit 19.
, from the FF state where the rear wheels are 0%, the distribution to the rear wheels is gradually increased and the front and rear wheels go through a 4WD state where both front and rear wheels are directly connected, and then the front wheels are 0%.
It changes within the range until the rear wheels reach 100% FR condition. When driving in four-wheel drive, if there is a difference in the effective diameter of the tires between the front and rear wheels due to a difference in the axle load distribution between the front and rear wheels of the vehicle, sudden acceleration, or movement of the center of gravity when climbing, then A relative rotation occurs. In such a case, the first or second wet hydraulic multi-plate clutch 7.28 functions as a torque limiter by being controlled to a desired clutch pressure, for example, the clutch plate 28c on the clutch drum 28a side and the clutch hub 28b side. Sliding occurs between the clutch disc 28e and the internal circulating torque caused by the difference in rotation between the front and rear wheels. Therefore, acceleration performance and fuel efficiency during four-wheel drive driving can be improved. Additionally, if you make a large steering turn while traveling eastward with 4-wheel drive, internal circulation torque will be generated between the front and rear wheels due to the difference in turning radius between the front and rear wheels, and this is especially large at low speed maximum steering, requiring more driving force than necessary. Therefore, when parking in the garage, etc.
Inconveniences such as engine stalling occur. In such a case, the first or second wet hydraulic multi-disc clutch 7.2
8 is the first or second wet hydraulic multi-disc clutch 7.28, which detects the above-mentioned front and rear rotational speeds and performs pressure reduction control to obtain a desired clutch pressure according to the rotational ratio or rotational difference.
To deal with this problem, create slippage inside. Therefore, the tight corner braking phenomenon during turning can be avoided. Also, the first or second wet hydraulic multi-disc clutch 7.2
When 8 performs such a sliding action, the desired friction characteristics are obtained because the multi-plate clutch, such as the clutch plate 28C and the clutch disc 28e, is immersed in an appropriate hydraulic oil with a predetermined composition. No slips occur. Therefore, unpleasant vibrations and noises do not occur, especially during low-speed maximum steering, and the desired reliability and durability of the friction material can be obtained. In such a four-wheel drive vehicle, each driving mode of FF, FR, and 4WD capable of distributing power between the front and rear wheels can be selected. For example, when the FF switch 43a is operated, a 0% duty ratio signal is output to only one duty solenoid valve 17a, and only the first wet hydraulic multi-disc clutch 7 is directly connected, and the second wet hydraulic multi-disc clutch 7 is directly connected. Since 28 is released, the power is transmitted only to the front wheels and becomes FF driving mode. When the FR switch 43b is operated, a 0% duty ratio signal is output only to the other duty solenoid valve 17b, the first wet hydraulic multi-disc clutch 7 is released, and only the second wet hydraulic multi-disc clutch 28 is released. Since it is directly connected, power is transmitted only to the rear wheels, resulting in FR driving mode. When the control 1n4WD switch 43c is operated, both duty solenoid valves 17a and 17b are set to zero.
A duty ratio signal in the range from % to 100% is output and the first. The pressure of the hydraulic oil applied to the second wet hydraulic multi-disc clutch 7.28 is changed according to the driving condition, thereby creating a controlled 4WD driving mode in which power is always distributed between the front and rear wheels. Therefore, by appropriately selecting each driving mode, the vehicle's handling, starting performance, and turning performance can be maximized, and the driving preference of the driver can be fully met. Now, looking at the behavior of the internal body of each wet-type hydraulic multi-disc clutch 7.28, in the first wet-hydraulic multi-disc clutch 7, the piston 7f rotates together with the clutch drum 7a as the transmission output shaft 9 rotates. In addition to the control hydraulic pressure, unnecessary centrifugal hydraulic pressure is generated in the chamber 7g, but at this time, the centrifugal hydraulic pressure chamber 42
Since the is filled with hydraulic oil, centrifugal oil pressure is generated that offsets the centrifugal oil pressure. Therefore, the piston 7r can be hydraulically controlled to a desired value without being influenced by the centrifugal hydraulic pressure in the hydraulic chamber 7g. On the other hand, in the second wet hydraulic multi-disc clutch 28, as the input shaft 31 rotates, the clutch drum 28
Even if the clutch plate 28C, the inner race 35c of the release bearing 35, etc. rotate together with the piston 281', the piston 281' is stopped by the cylinder portion 33, which is an immovable member, and does not rotate. Therefore, no centrifugal oil pressure is generated in the hydraulic chamber 211g formed between the piston 28'' and the cylinder portion 33, and no unnecessary pressing force is applied to the clutch plate 28c or the like other than the pressing force due to the control oil pressure. Therefore, the hydraulic pressure control of the hydraulic chamber 28g is accurate.
Subtle hydraulic control is also possible. In addition, since only one of the wet hydraulic multi-disc clutches 7.28 is placed at the end of the vertical transaxle automatic transmission that is integrated with the transfer, the transaxle does not become long and the device configuration is compact. becomes. Therefore, the transaxle maintains its rigidity and does not increase vibration or noise. Moreover, the space inside the vehicle is not reduced. Although the embodiments described above are based on a front-engine four-wheel drive vehicle, they may also be constructed based on a rear-engine four-wheel drive vehicle.

【Effect of the invention】

As explained above, according to the present invention, power is distributed to the front and rear wheels at an arbitrary ratio by changing the control hydraulic pressure to each wet hydraulic multi-plate clutch depending on the driving condition. When internal circulating torque is generated due to the rotational difference between the front and rear wheels, one or two wet hydraulic multi-disc clutches use an appropriate hydraulic fluid with a predetermined composition. This is fully absorbed by making the clutch exhibit the desired friction characteristics and smoothly sliding without stick-slip, thereby avoiding tight corner braking when turning and improving acceleration when driving straight. In addition to improving performance and fuel efficiency, it is also possible to prevent vibration noise from occurring. Because only one wet hydraulic multi-disc clutch is placed at the end of the vertical transaxle automatic transmission that is integrated with the transfer!・The lance axle does not become long and the device configuration becomes compact. Therefore, the transaxle can maintain its rigidity to avoid an increase in vibration and noise in the drive system, and also eliminate the reduction in vehicle interior space. Then, by operating the switch group, FF and FR. It is now possible to select each driving mode of the control 4WD, which can distribute power between the front and rear wheels, maximizing the vehicle's safety, single-start performance, and turning performance, while also being fully responsive to the driver's driving preferences. Can be done.

[Brief explanation of the drawing]

1(a) and 1(b) are sectional views of essential parts showing one embodiment of the present invention. 1. FIG. 1(c) is a sectional view taken along the line C--C of FIG. The figure is a schematic configuration diagram of a transmission system of a four-wheel drive vehicle to which one embodiment is applied, FIG. 3 is a hydraulic circuit diagram used in one embodiment, and FIG. 4 is a characteristic diagram of duty pressure and clutch pressure. 1...Engine, 2...Torque converter, 3...
- Front wheel differential device, 4... Automatic transmission, 5... Transfer device, B... Propeller shaft, 7... First wet hydraulic multi-disc clutch, 7a... Clutch drum, 71 ]... Clutch hub, 7c... Clutch plate, 7d... Retainer plate, 7e... Clutch disc, 7r... Piston, 7g... Hydraulic chamber,
8... Rear wheel differential device, 9... Transmission output shaft, 9a
...boss part, loa...transfer drive gear, tab...transfer driven gear, ti...
Front drive shaft, 12...drive pinion, 1
3... Final gear, 14a, 14b... Oil pump, 15a, 15b... Regulator valve, lea, 18b... Transfer clutch valve, 17a, 17b... Duty solenoid valve, 18a, 18b. ...Pilot valve, 19...
Control unit, 20... Valve unit, 2I...
Final gear, 22... Needle bearing, 23
...Bearing, 24...Transmission case, 25a. 25b... Seal ring, 26... Retainer ring, 27... Return spring, 28... Second wet hydraulic multi-plate latch, 28a... Clutch drum, 2
1tb...clutch hub, 28c...clutch plate, 28d...retainer plate, 28e...clutch disc, 28r...piston, 28g...
Hydraulic chamber, 29...Differential carrier, 30
...Drive pinion, 30a...Shaft part, 30b.
...Oil passage, 31...Input shaft, 31a...Flange part,
31b...oil passage, 32...extension case,
33... Cylinder part, 33a... Partition wall, 33b.
・・Inner guide cylinder, 34・・Thrust washer, 35・
...Release bearing, 35a...Outer race,
35b...Claw, 35cm...Innerless, 36.37
...Oil seal, 38...Snap ring, 39
...Seal ring, 40...Check valve, 41...
・Oil passage, 42... Centrifugal hydraulic chamber, 43a... FF switch, 43b... FR switch, 43c... Control 4W
D switch. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Noboru Kobashi Ukie

Claims (2)

[Claims] (1) In a four-wheel drive vehicle that is configured to transmit power between the front and rear wheels by changing the pressure of hydraulic oil to two wet-type hydraulic multi-disc clutches depending on the driving condition, one of the wet-type hydraulic multi-disc clutches is It is interposed between the output shaft of the vertical transaxle automatic transmission mechanism integrated with the transfer and the transfer gear for driving the drive pinion, and the other wet hydraulic multi-disc clutch is installed in the independent differential device after the propeller shaft. The control system for both wet-type hydraulic multi-disc clutches includes an FF that transmits power only to the front wheels via one of the wet-hydraulic multi-disc clutches.
Driving modes are selectable: FR driving, which transmits power only to the rear wheels via the other wet hydraulic multi-disc clutch, and 4WD driving, which transmits power to the front and rear wheels via both wet hydraulic multi-disc clutches. A power distribution device for a four-wheel drive vehicle that is equipped with a group of switches. (2) In a four-wheel drive vehicle that is configured to transmit power to the front and rear wheels by changing the pressure of hydraulic oil to two wet-type hydraulic multi-disc clutches depending on the driving condition, one of the wet-type hydraulic multi-disc clutches is configured to transmit power between the front and rear wheels. It is interposed between the output shaft of the vertical transaxle automatic transmission mechanism integrated with the transfer and the transfer gear for driving the drive pinion, and the other wet hydraulic multi-disc clutch is installed in the independent differential device after the propeller shaft. A power distribution device for a four-wheel drive vehicle that is arranged in sections and interposed in the middle of a transmission shaft.