JPS6325137A - Feour wheel drive device - Google Patents

Abstract

PURPOSE:To select either of maneuvering stability and running performance according to necessity or driver's desire by 5-steppedly switching two changeover clutches through the movement of a single shift lever, and thereby changing the drive torque distribution over the front and rear wheels positively. CONSTITUTION:Changeover clutches 9, 10 are interlockedly controlled in five steps by the use of a shift lever 18. In the position I, the rear drive shaft 3 is separated from planetary gearing mechanisms 4, 5 to become free, which causes front wheel drive condition. In the position II, the planetary gearing mechanisms 4, 5 switch the torque transmission path into the front torque increase side, which causes four-wheel drive condition chiefly served by the front wheels. In position III, the front drive shaft 2 and rear drive shaft 3 are put in direct coupling through changeover clutches 9, 10, that causes directly coupled four-wheel drive condition. In position IV, the planetary gearing mechanisms 4, 5 switch the torque transmission path into the rear torque increase side, that causes four-wheel drive condition chiefly served by the rear wheels. In position V, the front drive shaft 2 is separated from the planetary gearing mechanism 5 to become free, that causes the rear wheel drive condition. For prevention of slip rotation, a viscous coupling 8 is provided between said planetary gearing mechanism 5 and the front drive shaft 2.

Description

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

This invention makes it possible to arbitrarily control the drive torque distribution between the front and rear wheels in a full-time four-wheel drive vehicle equipped with a center differential, thereby changing the steering stability and driving performance according to the purpose or preference. The present invention relates to a four-wheel drive device.

[Conventional technology]

Conventionally, for four-wheel drive vehicles with a center differential, a differential gear device is used for the center differential, and a dog locking device is used to restrict the operation of the center differential, as shown in Japanese Patent Laid-Open No. 55-724320, for example. Some were equipped with a clutch.

[Problems to be solved by the invention]

By the way, in the configuration of the prior art described above, since the differential gear device as a center differential has two side gears having the same diameter mechanically, the drive torque distribution between the front and rear wheels is always approximately equal. become. Therefore, it has not been possible to actively change the drive torque distribution. Further, the dog clutch only has a differential lock function that integrally locks the differential gear device for emergency escape when one of the front and rear wheels is idling. In a four-wheel drive vehicle, by changing the torque distribution of front wheel torque TF and rear wheel torque TR based on various driving conditions, not only driving performance but also handling such as turning performance and stability can be improved. It is known to be scaly. Therefore, even in full-time 4-wheel drive vehicles with center differentials, it has been desired to actively control torque distribution to improve handling and driving performance. There has never been a four-wheel drive device that can achieve both TF > TR and T < TR using only the device. This invention was made in view of these points, and provides a four-wheel drive system that actively changes the drive torque distribution between the front and rear wheels and allows you to select steering stability and driving performance according to your purpose or preference. The purpose is to provide

[Means to solve the problem]

The four-wheel drive device according to the present invention has a center differential configured with first and second planetary gear mechanisms for torque splitting, and a first switching clutch and a first switching clutch between the second planetary gear mechanism and the front wheel drive shaft. A viscous coupling for preventing slippage is disposed between the first and second planetary gear mechanisms and the rear wheel drive shaft via a gear mechanism, and a second switching clutch is disposed between the first and second planetary gear mechanisms and the rear wheel drive shaft. By switching the switching clutch in five stages in conjunction with a single switching lever, five different drive states can be selected: front-biased 4-wheel drive, direct-coupled 4-wheel drive, rear-biased 4-wheel drive, and rear-wheel drive. This allows you to choose.

[For production]

Based on the above configuration, when the first and second switching clutches are linked and switched to five stages by the switching lever, the first
In the position, the rear wheel drive shaft is disconnected from the first and second planetary gear mechanisms and becomes free, resulting in a front wheel drive state. In the second position, the torque transmission paths of the first and second planetary gear mechanisms are switched to the front torque increasing side, resulting in a four-wheel drive state closer to the front wheels. In the third position, the front and rear drive shafts are
The two wheels are directly connected by the second switching clutch, resulting in a direct four-wheel drive state. In the fourth position, the first and second
The torque transmission path of the planetary gear mechanism is switched to the side with a larger rear torque layer, resulting in a four-wheel drive state closer to the rear wheels. In the fifth position, the front wheel drive shaft is disconnected from the second planetary gear mechanism and becomes free, resulting in a rear wheel drive state. In addition, in the second and fourth positions, the viscous coupling is activated, and when one wheel side slips, it applies the driving force to the other wheel side according to the rotation difference between the front and rear drive shafts. Increase the amount of water and try to escape from the slip state. In this way, it becomes possible to select the optimum driving state according to various road surfaces, driving purposes, or preferences.

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In FIG. 1, reference numeral 1 denotes a hollow input shaft supported by a transmission case, into which a driving torque T from the transmission is input. 2 is a front wheel drive shaft supported within the input shaft 1, which transmits front torque TF-. 3 is a rear wheel side drive shaft which is supported by the transmission case and transmits rear torque T9. A first planetary gear mechanism 4 is composed of a plurality of planetary pinions 4a, a sun gear 4b, and a hollow shaft 4c integrated therewith. 5 is a second planetary gear mechanism, which includes a plurality of planetary pinions 5a, a sun gear 5b, and a ring gear 5c. It is composed of a hollow shaft 5d integral with this. 6 is a shaft connecting both planetary pinions 4a and 5a, 7 is a shaft 6
The carrier is connected to the input shaft 1 through which the planetary pinions 4a and 5a revolve. Reference numeral 8 designates a viscous coupling, which includes a housing 8a having one end connected to a hollow shaft 5d and a hollow shaft protruding from the other end, a hollow shaft-shaped hub 8b extending from the sun gear 5b, and a plurality of viscous couplings erected from each. The plates are inserted into each other and filled with a highly viscous fluid, and when a difference in rotation occurs between the housing 8a and the hub 8b, a corresponding torque is generated. 9 is a first switching clutch, which has internal teeth 9ai*9a219a3
a gear 9b1 that can be engaged in 3 positions and a gear 9b2 that can be engaged in 1 position, which are integral with the hollow shaft 8C.
, a gear 9b that engages in one position and is integral with the hollow shaft-shaped hub 8b;
, a gear 9b4 that can be engaged in 3 positions, and a front wheel drive shaft 2.
It consists of a gear 9b that can be engaged in four positions and is fixed to the gear 9b. 10 is the second switching clutch, inner WJ10a
1°10a, , 10a3, a gear 10b2 that can be engaged in 5 positions and is fixed to the rear drive shaft 3, and a gear 10b1 that can be engaged in 1 position and is rotatably supported on the shaft 3. Gear 1 that can be engaged in 3 positions
0b3. 11.12.13.14
is a gear, 15 is a propeller shaft, 16 is a rear hub, 1
7 is a selector bar, 17a is a fork that engages with the sleeve 9a, 17b is a fork that engages with the sleeve 10a,
Reference numeral 18 is a switching lever that allows selection of positions from TV to V. Next, regarding the operation of the four-wheel drive device configured in this way, the first and second switching clutches 9, 1 shown in FIG.
This will be explained with reference to the engagement state of 0 and the drive torque distribution diagram shown in FIG. First, when the switching lever 18 is set to position E, as shown in FIG. As a result, the rear drive shaft 3 is released from the input shaft 1 via the gear 12.13. Further, the first dog clutch 9 integrally connects the front wheel side drive shaft 2, the hub 8b, and the hollow shaft 8C, the viscous coupling 8 is inactive, and the second
Since the planetary gear mechanism 5 of is prevented from planetary motion,
The drive torque T of the input shaft 1 is directly transmitted to the front-wheel drive shaft 2, resulting in a front-wheel drive state and stability at high speeds. Next, when the switching lever 18 is switched to position (3), the first and second switching clutches 9.10 become engaged as shown in FIG. 2(b), and the teeth 9a2. does not engage with any of the gears 9b, 9b4, so the viscous coupling 8
a and the hub 8b are in an operating state in which they can rotate relative to each other. In this state, the driving torque T input from the input shaft 1 causes both the planetary pinions 4a and 5a to revolve through the carrier 7, and the planetary pinion 5a and the ring gear 5 are sent to the front drive shaft 2.
c, housing 8a1 gear 9 of viscous coupling 8
b1 and the tooth 9a1, the front torque TF is transmitted through the selector sleeve 9a, and the rear torque TR is transmitted to the rear drive shaft 3 through the planetary pinion 4a1, sun gear 4b, gears 11 and 12, and the second switching clutch 10. However, depending on the gear ratio of sun gear 4b and ring gear 5C, a four-wheel drive state is established where Tq>TR, with the front wheels being closer to the front wheels. Here, in the viscous coupling 8, in normal running conditions, there is no rotation difference between the housing 8a and the hub 8b, so no coupling torque is generated.
When the front wheel with a large drive force distribution slips, the housing 8a tries to rotate at high speed, and in response to the resulting rotational difference with the hub 8b, a coupling torque TC is generated, which is added to the low-speed side coupling torque T. Therefore, the front torque TF temporarily becomes T-(T, +TC), and the drive torque of the rear wheel drive shaft 3 increases, making it possible to easily escape from the slip state. Next, when the switching lever 18 is switched to position ■,
The first and second switching clutches 9 and 10 are shown in FIG. 2(C).
The first switching clutch 9 brings the viscous coupling 8 into an inoperative state in which the housing 8a and the hub 8b cannot rotate relative to each other, and the second planetary gear mechanism 5 also switches between the sun gear 5b and the ring gear. 5C is integrated to prevent its planetary motion, and the front and rear drive shafts 2.3 are directly connected by the m wheel 13.14.
It becomes a direct four-wheel drive state. In this driving state, the running performance on rough roads and the stability on low μ roads are improved. Furthermore, when the switching lever 18 is switched to the position (3), the first and second switching clutches 9 and 10 are engaged as shown in FIG. 2 (Φ), the viscous coupling 8 is activated, and the The torque transmission path in the first and second planetary gear mechanisms 4.5 is at position ■(
The drive torque T via the carrier 7 is the opposite of the front wheel drive (four-wheel drive closer to the front wheels), and the drive torque T via the carrier 7 is transmitted to the front wheel side drive shaft 2 through the planetary pinion 5a,
The front torque T is transmitted through the sun gear 5b and the hub 8b, and the rear torque T is transmitted to the rear drive shaft 3 through the planetary pinion 5a, the ring gear 5C1, the hollow shaft 5d, the gears 13 and 14, and the selector sleeve 10a. Depending on the gear ratio of 5b and ring gear 5C,
TkuT It becomes a four-wheel drive state with the rear wheels closer. In this driving state, turning performance and starting performance are improved, and
Since the viscous coupling 8 is activated, if the rear wheel with a large drive torque distribution slips, it will be activated in the same way.
Increases the drive torque on the front wheel side to help escape from a slip situation. Furthermore, when the switching lever 18 is switched to position V,
The first and second switching clutches 9.10 are shown in Figure 2 (Q).
The engagement state shown in FIG. 1 is reached, and the front wheel drive shaft 2 is disconnected from the second planetary gear mechanism 5 via the selector sleeve 9a and becomes free, and the drive torque T via the carrier 7 is prevented from planetary motion. All of the power is transmitted to the rear wheel drive shaft 3 via the second planetary gear mechanism 5 and the m wheels 13 and 14, resulting in a rear wheel drive state. In this driving state, turning performance is improved. Note that in the above embodiment, the first. Although it has been described that the second dog clutch 9, 10 is switched by manual operation of the switching lever 18, it may be operated electrically or pneumatically. Effects of the Invention As described above, according to the present invention, the center differential is configured with two sets of planetary gear mechanisms and viscous couplings, and the first and second switching systems switch front and rear wheel drive torque distribution. The clutch is linked by a switching lever and can be switched in 5 stages, allowing you to select from 5 different drive states, so you can select from 5 different drive states, from front wheel drive to rear wheel drive, depending on driving conditions or preference. This has the effect of improving steering stability, running performance, and running performance on rough roads.

[Brief explanation of the drawing]

FIGS. 1 to 3 are diagrams showing an embodiment of the present invention,
Figure 1 is a skeleton diagram showing the configuration of the four-wheel drive system, Figure 2
Figure 1. FIG. 3, which is a diagram showing the engaged state of the second switching clutch, is a drive torque distribution table. DESCRIPTION OF SYMBOLS 1... Input shaft, 2... Front wheel side drive shaft, 3... Rear wheel side drive shaft, 4... First planetary gear mechanism, 5...
- Second planetary gear mechanism, 8... Viscous coupling, 9... First switching clutch, 10... Second
switching clutch, 11-14...gear, 18... switching lever.

Claims (1)

[Claims] The center differential is the first and second one for torque splitting.
A first switching clutch and a viscous coupling for preventing slippage are connected between the second planetary gear mechanism and the front wheel drive shaft, and a first switching clutch and a viscous coupling for preventing slip are connected between the first and second planetary gear mechanisms and the rear wheel side. A second switching clutch is disposed between the drive shaft and the drive shaft via a gear mechanism, and the first and second switching clutches are interlocked by a single switching lever and switched in five stages to achieve front wheel drive. A four-wheel drive device characterized in that five different drive states can be selected: , front-biased 4-wheel drive, direct-coupled 4-wheel drive, rear-biased 4-wheel drive, and rear-wheel drive.