JPH057071Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a drive device for a four-wheel drive vehicle having a center differential consisting of a planetary gear mechanism.

[Conventional technology]

Generally, in the case of two-wheel drive vehicles such as FF and FR vehicles, in order for the vehicle to turn easily,
In order to create a rotation difference between the inside and outside of the drive wheel,
A differential gear or differential is provided between the left and right wheels.

However, if one tire completely slips on a snowy or muddy road, that tire will simply spin, and the driving force from the engine will not be transmitted to the tire that is gripping the ground firmly. An inconvenient situation arises in which there is no such thing.

Therefore, if only one tire spins excessively, the differential function is temporarily stopped, the system rotates as a whole, and the driving force is transmitted to the tire that is gripping the ground. , a deflock device is provided.

In addition, in the case of a full-time four-wheel drive vehicle, since the vehicle literally drives four wheels on the front, rear, left and right sides, the structure must be such that the four wheels rotate differently. Therefore, in addition to the front differential between the left and right wheels installed between the front wheels, and the rear differential between the left and right wheels installed between the rear wheels, we installed a device that distributes the engine's driving force between the front and rear wheels, and a third differential, the center differential ( That is, a central differential) is provided. Furthermore, in order to avoid a situation where some of the tires spin idly, a differential lock mechanism is provided in the center differential.

By the way, various improvements have been made to the power transmission system including the center differential in order to enable the conventional transaxle case for two-wheel drive vehicles to be used in four-wheel drive vehicles with minimal modification. It is being As an example, Tokko Akira
A four-wheel drive vehicle as described in Publication No. 62-9060 is disclosed. This four-wheel drive vehicle will be outlined with reference to FIG. 4 (which shows a portion of FIG. 1 in the above publication).

The conventional four-wheel drive vehicle drive device shown in FIG. 4 is of a horizontal engine type, with the engine 5 disposed so that the crankshaft 52 extends in the lateral direction of the vehicle body.
1, a transmission 56 having a transmission mechanism between an input shaft 54 and an output shaft 55 arranged to extend in the transverse direction of the vehicle body within the transaxle case 53; The output shaft 5 of the transmission 56 is arranged substantially coaxially with either one of the axles 61.
The final reduction gear 57 is rotationally driven by the final reduction gear 57 within the transaxle case 53.
A central differential device 59 is provided inside a casing 58 that rotates integrally with the transaxle case 53, and a central differential device 59 is disposed substantially coaxially with the axle 61 within an additional housing 60 connected to the transaxle case 53 and is drivingly connected to the central differential device 59. It is driven by a differential gear mechanism 62 on either one of the front wheels or rear wheels, and a central differential gear 59, converting the rotational direction of the driving force at right angles to generate a difference between the front wheels or the rear wheels on the other side. A direction conversion gear set 63 for transmitting information to the dynamic gear mechanism is provided.

Furthermore, in recent years, viscous clutches have come to be used as defrock mechanisms, and such a full-time transfer based on FR vehicles is disclosed, for example, in Japanese Patent Application Laid-Open No. 158765/1983.

[Problem that the invention attempts to solve]

However, as mentioned above,
In a four-wheel drive vehicle as described in Publication No. 9060, a differential gear mechanism 62 for the front or rear wheels is installed in the transaxle case 53 of a two-wheel drive vehicle, that is, the part rotates integrally with the final reduction gear 57. In the casing 58, there is a center differential or central differential device 5.
9 is incorporated into the additional housing 60 attached to the transaxle case 53 to either the front wheel or rear wheel differential gear mechanism 62, and the other of the front wheel or rear wheel differential gear mechanisms. By providing a direction conversion gear set 63 that converts the rotational direction of the driving force to a right angle for transmitting the driving force, a four-wheel drive vehicle equipped with a central differential device 59 can be created by slightly changing the transaxle of a two-wheel drive vehicle. It is configured so that it can be used in conjunction with the transaxle.

However, when the central differential 59 is locked, the front wheels and rear wheels are completely directly connected.
If the vehicle makes a small circle turn in such a state, there is a problem in that a so-called tight corner braking phenomenon occurs. Furthermore, in this four-wheel drive vehicle, when separating the oil in the transaxle case 53 and the additional housing 60, in the layout of the four-wheel drive vehicle described above, driving force is transferred from the transaxle case 53 side to the additional housing 60. Since a shaft with a multiplex structure is used to transmit power to the side, a large number of sealing parts such as oil seals must be used.
There are also problems with the lubrication system.

Furthermore, in the four-wheel drive vehicle having a control clutch disclosed in the above-mentioned Japanese Patent Application Laid-open No. 50-158765,
A type of bevel type center differential in which a viscous clutch is added to the outer periphery has a problem in that the entire device becomes larger in the radial direction.

The purpose of this invention is to solve the above-mentioned problems, by using a viscous clutch as a mechanism for limiting the differential movement of the center differential, placing the center differential inside the transaxle case, and placing the viscous clutch within the transaxle case. Place it inside the case,
The viscous clutch absorbs the relative rotation between the front wheels and the rear wheels without the driver's operation, that is, it does not completely lock the center differential, but allows some relative rotation, and when the vehicle makes a small circle turn, it can be tightened. Prevents corner braking and prevents the vehicle from swaying when either the front or rear wheels spin. For example, when one wheel slips on a snowy or muddy road, the other three wheels are also activated. It is configured so that power is transmitted, and the torque distribution between the front and rear wheels can be arbitrarily selected according to the distributed load. It is an object of the present invention to provide a drive device for a four-wheel drive vehicle, which has a structure in which oil, that is, lubricating oil, can move between the four-wheel drive vehicles, reduces the number of sealing parts, and improves the lubrication function by circulating the oil.

[Means for solving problems]

In order to achieve the above object, this invention is constructed as follows. That is, this invention consists of a center differential consisting of a planetary gear mechanism on a drive shaft disposed within a transaxle case, an output gear disposed within the transaxle case transmission connected to a carrier shaft extending from the center differential by spline fitting, and an output gear adjacent to the output gear. a center differential differential limiting device transmission-connected to the center differential differential limiting device; a differential between the left and right wheels adjacent to the center differential differential limiting device;
a shaft disposed on the carrier shaft and extending from the differential box of the center differential extending from inside the transaxle case into the transfer case; and an oil extending in the longitudinal direction through which lubricating oil formed on the inner peripheral surface of the shaft can move. groove,
The present invention relates to a drive device for a four-wheel drive vehicle.

Further, in this drive system for a four-wheel drive vehicle, the center differential differential limiting device is configured with a viscous clutch, the carrier shaft is transmission connected to an outer case of the viscous clutch via the output gear, and the sun gear of the planetary gear mechanism is connected to the outer case of the viscous clutch through the output gear. The shaft is transmission connected to the drive shaft through the differential box of the differential, and the drive shaft is transmission connected to the inner case of the viscous clutch through the differential box.

Further, in this four-wheel drive vehicle drive device, oil seals are used to seal between the casing housing the center differential and the drive shaft, and between the transaxle case and the shaft.

[Effect]

The drive system for a four-wheel drive vehicle according to this invention is constructed as described above and operates as follows.
That is, in this drive system for a four-wheel drive vehicle, oil is not present between the multiple shafts extending from the inside of the transaxle case to the inside of the transfer case, that is, between the carrier shaft extending from the center differential and the shaft extending from the differential box of the center differential. Since an oil groove extending in the longitudinal direction is formed on the inner circumferential surface of the shaft to allow movement, the number of sealing parts can be reduced.
The lubrication function can be improved by circulating oil between the transaxle case and the transfer case.

In addition, a center differential is placed inside the transaxle case, and a viscous clutch, which is a center differential differential limiting clutch, and a differential between the left and right wheels are placed inside the transfer case, so that the viscous clutch is distributed by the center differential. If there is an excessive rotational speed difference in the two drive systems, that is, between the front wheels and the rear wheels, the viscous clutch is activated immediately to limit the differential movement of the center differential, and the difference between the front wheels and the rear wheels is reduced. Excessive relative rotation can be reduced. In addition, the viscous clutch does not completely lock the center differential and allows some relative rotation, so it functions to prevent tight corner braking from occurring when the vehicle makes a small circle turn.

〔Example〕

Hereinafter, embodiments of the four-wheel drive vehicle drive system according to the invention will be described in detail with reference to the drawings. With this idea, a conventional power transmission system can be applied until the driving force from the engine reaches the final reduction gear, which is the input gear, and the output side of the planetary gear mechanism and the drive shaft with a differential etc. Since various conventionally known power transmission systems can be applied to the power transmission system, in the following description of the embodiments of this invention, the lubrication system of the drive device for a four-wheel drive vehicle according to this invention and the driving force of the engine will be used. The explanation will focus on the planetary gear mechanism and center differential differential limiting clutch related to the center differential, which is a central differential that distributes the amount of torque between the front and rear wheels.

In addition, regarding this four-wheel drive vehicle drive system,
In the illustration of FIG. 1, for example, it is assumed that the device is mounted on the vehicle body such that the upper side corresponds to the front side of the vehicle body and the lower side corresponds to the rear side of the vehicle body. Although it goes without saying that the front and rear drive systems may be configured in reverse, the drive system is configured as described above.

First, with reference to FIG. 1, an embodiment of a four-wheel drive vehicle drive system according to this invention will be described. This four-wheel drive vehicle drive device 10 is applied to a horizontally mounted engine, and is disposed within a case in which a transaxle case 5 and a transfer case 6 are combined. This four-wheel drive vehicle drive device 10 includes:
The center differential 2 mainly consists of a planetary gearing or planetary gear mechanism disposed in the transaxle case 5, and the viscous clutch 1, which is a center differential differential limiting clutch disposed in the transfer 6, and adjacent to the viscous clutch 1. It consists of a front differential 3 located between the left and right wheels.

Driving power from an engine (not shown) is transmitted from the output shaft of a suitable manual or automatic transaxle to the input gear 7 of the final reduction gear. The input gear 7 is a helical gear, and a bolt 39 is attached to the casing 8 and the center differential box 9 of the center differential 2.
Furthermore, a gasket 17 is interposed between the casing 8 and the center differential box 9 to perform a sealing function between the two.

Center differential 2 mainly consists of center differential box 9 and pinion 2 which is a planetary gear.
2, and a sun gear 23 integrally formed with the sun gear shaft 18. The casing 8 is supported by the transaxle case 5 via a bearing 11, and the center differential box 9 of the center differential 2 is supported by the transaxle case 5 via a bearing 16. That is, the center differential 2 consisting of a planetary gear mechanism is disposed within the transaxle case 5.

Therefore, the driving force from the engine is input to the center differential box 9 through the input gear 7. In addition, a ring gear 21 is provided on the inner peripheral surface of the center differential box 9.
A pinion 22 is meshed with the ring gear 21. Furthermore, pinion 22
is supported by a pinion shaft 19 supported by a carrier 24, and meshes with the sun gear 23. The sun gear 23 is integrally formed with an axially extending sun gear shaft 18 , and the carrier 24 supporting the planetary gear or pinion 22 is integrally formed with the axially extending carrier shaft 13 , and the sun gear shaft 18 is integrally formed with the carrier shaft 1 .
It is rotatably arranged on the inner peripheral side of 3.

Further, the center differential box 9 is integrally formed with a shaft 40 that extends in the axial direction over the carrier shaft 13 and extends into the transfer case 6. This shaft 40 constitutes a multi-structured shaft, that is, a multi-shaft, with the carrier shaft 13 and the sun gear shaft 18, and is located at the outermost position.

An oil seal 41 with a two-way lip is disposed on the transaxle case 5 side between the transaxle case 5 and the shaft 40 at the joining site between the transaxle case 5 and the transaxle case 6. It fulfills the sealing function. Furthermore, a front wheel drive shaft 15 extending from the front differential 3 for between the left and right wheels passes through the inner peripheral side of the sun gear shaft 18 in a freely rotatable manner. A two-way lipped oil seal 42 is placed between the two for sealing.

Further, a viscous clutch 1 is disposed on the same axis as a center differential 2 disposed within the transaxle case 5, and a front differential 3 is disposed adjacent to the viscous clutch 1 on the same axis. has been done.

This viscous clutch 1 performs a center differential differential limiting function and a differential locking function, that is, it has a function of automatically absorbing relative rotation between the front wheels and the rear wheels. The outer case 12 of the viscous clutch 1 is connected to a gear shaft 20 on which a rear output gear 27 is formed, and the end of the gear shaft 20 is spline-fitted (at the position 47) to the end of the carrier shaft 13. There is. Therefore, the viscous clutch 1 has a bearing 26 and a bearing 35.
It is arranged in the transfer case 6 via the above.

Further, one end of the inner case 14 of the viscous clutch 1 is spline-fitted 44 to the sun gear shaft 18, and the other end is spline-fitted 45 to the end of the differential box 25 of the front differential 3. Therefore, the front differential 3 is disposed within the transfer case 6 via the bearing 38, the inner case 14 of the viscous clutch 1, and the like.

Furthermore, the outer case 12 of the viscous clutch 1
The rear output gear 27 fixed to the rear output gear 27 is a helical gear, and the driving force from the rear output gear 27 is transmitted to the direction changing mechanism 4 consisting of a gear 30, a ring gear 31, and a pinion 32, a pinion shaft 33, and a flange. 34, the signal is transmitted to a rear differential for left and right wheels, a rear wheel drive shaft, etc. (not shown).

Further, the viscous clutch 1 is a viscous coupling ring, and has a case in which a number of disc-shaped plates (not shown) and silicone oil are sealed. An outer disk (not shown) is spline-fitted to the inner peripheral surface of an outer case 12 of the viscous clutch 1, and an inner disk (not shown) is spline-fitted to the outer peripheral surface of the inner case 14. Moreover, these outer disks and inner disks are arranged alternately within a sealed chamber filled with silicone oil.

Furthermore, the bevel type front differential 3 includes a differential box 25, a pinion shaft 37, a pinion 32, and a side gear 28.
are connected to left and right front wheel drive shafts 15, 15'. By the way, the differential box 2 of the front differential 3
5 end and inner case 1 of viscous clutch 1
4 is spline fitted 45 to one end of the inner case 14, and the other end of the inner case 14 is spline fitted 44 to the end of the sun gear shaft 18. Therefore, the differential box 25 and the sun gear 23 are transmission connected. It turns out.

In FIGS. 2 and 3, the shaft 4 of the center differential box 9 in the center differential 2 is extended.
0 is shown. 2 is a side view of the shaft 40 shown in FIG. 1, and FIG. 3 is a sectional view taken along the line - in FIG. shaft 40
A protrusion 46 is formed on the upper and lower ends of the shaft 40, and an oil groove 43 is formed in a spiral shape on the inner peripheral surface of the shaft 40. Although the oil groove 43 is shown as having a spiral shape, it goes without saying that it may also be formed in a straight line.

Next, the operation of the four-wheel drive vehicle drive system according to this invention will be explained. The driving force from the engine is transmitted to the input gear 7, which is the final reduction gear, via the transmission. The power is transmitted to a ring gear 21 formed on the inner peripheral surface. Here, the driving force is divided into two parts and transmitted.

First, on the one hand, the driving force input to the ring gear 21 is transmitted from the carrier 24 supporting the pinion 22, which is a planetary gear, to the gear 30, the ring gear 31, and the pinion 32 via the carrier shaft 13, the gear shaft 20, and the rear output gear 27. ,
The power is transmitted sequentially through the pinion shaft 33 and the flange 34, and then, although not shown, is transmitted to a rear wheel transmission shaft such as a propeller shaft fixed to the flange 34, and then to the rear wheel drive shaft through the rear differential. communicated.

On the other hand, the driving force input to the ring gear 21 is sequentially transmitted from the pinion 22 to the sun gear 23, the sun gear shaft 18, the inner case 14 of the viscous clutch 1, and the differential box 25 of the bevel type front differential 3. Pinion 32 and side gear 2 of bevel type front differential 20
8 to the left and right front wheel drive shafts 15, 15'.

The above-mentioned operation of the drive device for a four-wheel drive vehicle according to this invention is particularly characterized by the following points. That is, the shaft 40, which is an extension of the differential box 9 in the center differential 2, and the carrier shaft 13, which is an extension of the carrier 24 of the center differential 2, rotate relative to each other. As described above, this shaft 40 has a protrusion 46 and an oil groove 4.
3 is formed. Therefore, when the shaft 40 and the carrier shaft 13 rotate relative to each other,
Oil, or lubricating oil, collects in the protrusion 46 and travels with it through the oil groove 43, and thus can move from within the transfer case 6 into the transaxle case 5, or vice versa; , oil, that is, lubricating oil, can flow between the center differential 2 disposed in the transaxle case 5 and the transfer case 6, and the lubricating oil can be circulated extremely well and reliably, thereby improving the lubrication system. The lubrication effect can be improved. Furthermore, by simply sealing the inside of the transaxle case 5 with the two oil seals 41 and 42 with two-way lips, the parts to be lubricated can be completely sealed. If the center differential box 9 is separated from the casing 8 as shown in FIG. 1, a gasket 17 or the like may be interposed between the casing 8 and the center differential box 9 to form a seal. good.

By the way, this four-wheel drive vehicle drive device 10 is
The driving force from the engine is distributed through the operations described above. Furthermore, the outer case 12 and outer disc of the viscous clutch 1, which is a center differential differential limiting clutch, are connected to the same drive system as the drive system that transmits the driving force of the engine to the rear wheel drive shaft via the carrier shaft 13 of the center differential 2. The inner case 14 and inner disc in the viscous clutch 1 are rotated by the driving force of the same drive system as that transmitted to the front wheel drive shafts 15, 15'. .
In normal cases, there is a predetermined rotational difference between the front wheels and the rear wheels, and the outer disk of the outer case 12 and the inner disk of the inner case 14 rotate relative to each other.

However, when one of the wheels spins idly on a snowy road, muddy road, etc., an excessive rotational difference occurs between the front wheels and the rear wheels. When such an excessive rotational difference occurs between the front and rear wheels, excessive relative rotation occurs between the inner disk and the outer disk, resulting in shearing force between these disks. This shearing force increases wear resistance and acts to reduce the rotational difference between the inner disk and the outer disk, thereby limiting the differential movement of the center differential 2. In some cases, the inner disk and outer disk are integrated and directly connected, functioning as a differential lock that transmits rotational force to the drive system to which it is not being transmitted.

[Effect of idea]

The drive device for a four-wheel drive vehicle according to this invention is constructed as described above, and has the following effects. That is, this drive system for a four-wheel drive vehicle has a center differential disposed within a transaxle case, a viscous clutch serving as a differential limiting clutch for the center differential, and a differential for left and right wheels disposed within the transfer case, and the transaxle. Since the lubricating oil is configured to be able to move between the multiple shafts extending from inside the axle case to the transfer case,
When the viscous clutch is used as a mechanism to limit the differential movement of the center differential, and the viscous clutch causes an excessive difference in rotation speed in the two drive systems distributed by the center differential, that is, between the front wheels and the rear wheels. The viscous clutch can immediately operate to limit the differential movement of the center differential and reduce excessive relative rotation between the front and rear wheels.

That is, the relative rotation between the front wheels and the rear wheels is absorbed by the viscous clutch without the driver's operation of the center differential differential limiting function and the differential locking function, that is, the center differential is not completely locked, but the relative rotation is limited to a certain extent. This prevents tight corner braking from occurring when the vehicle makes a small circle turn, and prevents the vehicle from wandering when either the front or rear wheels spin, for example.
The structure is such that when a wheel gets stuck on a snowy road, muddy road, etc., for example, when one wheel slips, the driving force is transmitted to the other three wheels, and the durability of the viscous clutch is improved. The seal component is configured such that torque distribution can be arbitrarily selected according to the distributed load, and further configured to allow oil, that is, lubricating oil, to move between the inside of the transaxle case and the inside of the transfer case. In other words, the parts to be lubricated can be completely sealed by simply sealing the interior of the transaxle case with two oil seals with two-way lips. Oil, that is, lubricating oil, can be extremely easily passed between the center differential and the transfer case, and the lubricating oil can be circulated extremely well and reliably, thereby improving the lubrication function of the lubrication system. can.

In addition, since the center differential, the viscous clutch, and the differential are arranged in series on the same axis, various devices for four-wheel drive vehicles can be implemented with minimal changes to the conventional transaxle case for two-wheel drive vehicles. This means that it can be installed. Furthermore, since the viscous clutch and the output gear can be fixed coaxially, they do not protrude in the radial direction and do not require space, so the distance between the engine crankshaft and the front wheel drive shaft can be shortened. Furthermore, the distance to the road surface can be increased, creating more leeway in the layout, and making it extremely easy to mount a transverse transaxle-based full-time transfer to the front wheel drive axle.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a four-wheel drive vehicle drive system according to this invention, FIG. 2 is a side view showing the multiple shafts shown in FIG. 1, and FIG.
and FIG. 4 are skeleton diagrams showing the drive system of a conventional four-wheel drive vehicle. 1...Viscous clutch, 2...Center differential,
3... Front differential, 5... Transaxle case, 6... Transfer case, 7... Input gear, 8... Casing, 9... Center differential box, 10... Drive device for four-wheel drive vehicle, 12 ...Outer case, 13...Carrier shaft, 14...
...Inner case, 15,15'...Front wheel drive shaft,
18... Sun gear shaft, 20... Gear shaft, 23... Sun gear, 24... Carrier, 25
...Diff box, 40...Shaft, 41,4
2...Oil seal, 43...Oil groove.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A center differential consisting of a planetary gear mechanism on a drive shaft disposed within a transaxle case, and an output gear disposed within the transfer case that is transmission connected by spline fitting to a carrier shaft extending from the center differential. , a center differential differential limiting device transmission-connected adjacent to the output gear; a differential between the left and right wheels adjacent to the center differential differential limiting device; A drive device for a four-wheel drive vehicle, comprising: a shaft extending from a differential box of the center differential; and an oil groove formed on the inner circumferential surface of the shaft and extending in a longitudinal direction through which lubricating oil can move. (2) The center differential differential slip limiting device is constituted by a viscous clutch, the carrier shaft is transmission connected to the outer case of the viscous clutch via the output gear, and the sun gear shaft of the planetary gear mechanism is connected to the outer case of the viscous clutch via the differential box of the differential. The drive device for a four-wheel drive vehicle according to claim 1, which is transmission-coupled to the drive shaft, and the drive shaft is transmission-coupled to the inner case of the viscous clutch via the differential box. (3) The four-wheel drive according to claim 1, wherein oil seals are used to seal between the casing housing the center differential and the drive shaft and between the transaxle case and the shaft. Car drive system.