JPS6325139A - Four 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 which shall be put in mo-ion through the use of a single shift lever, and thereby changing the drive torque distribution over the front and rear wheels positively. CONSTITUTION:Changeover clutches 8, 9 are interlockedly controlled in five steps by the use of a shift lever 20. 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 are switched into a path where the front torque is increased, 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 the planetary gearing mechanisms 4, 5, that causes directly coupled four-wheel drive condition. In position IV, the planetary gearing mechanisms 4, 5 are switched into a path where the rear torque is increased, 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 14 is provided between the front and rear wheel drive shafts 2, 3.

Description

[Detailed description of the invention]

[Industrial Application Field] This invention is a full-time four-wheel drive vehicle equipped with a center differential, in which drive torque distribution between the front and rear wheels can be arbitrarily controlled to improve steering stability and driving performance according to the purpose or preference. The present invention relates to a four-wheel drive device that can be changed according to the conditions. [Background Art] Conventionally, as shown in Japanese Patent Laid-Open No. 55-72420, for example, in a four-wheel drive vehicle with a center differential, a differential gear is used for the center differential device, and the center differential device is used to limit the operation of the differential gear. Some models are equipped with a dog clutch that locks the

[Problems to be solved by the invention]

By the way, in the configuration of the above-mentioned prior art, the differential gear device as a center differential has two side gears having the same diameter mechanically, so the front,
The drive torque distribution to the rear wheels is always approximately equal. Therefore, it has not been possible to actively change the drive torque distribution. In addition, the dog clutch merely has a differential lock function that integrally locks the differential gear device for emergency escape in the event that one of the front and rear wheels is idling. In a four-wheel drive vehicle, changing the torque distribution of front wheel torque TF and rear wheel torque TR based on various driving conditions improves turning performance in addition to driving performance. It is known that handling stability such as stability can also be improved. Therefore, even in full-time 4-wheel drive vehicles with center differentials, it has been desired to actively control torque distribution to improve handling stability and driving performance. Front wheel torque TF with drive unit only
and rear wheel side torque TR, TF>TR and TF<TR
Currently, there is no four-wheel drive device that can achieve both of these. This invention was made in view of these points, and it is possible to actively change the torque distribution between the front and rear wheels to change the steering stability and driving performance according to the purpose or preference. The purpose is to provide a wheel drive device.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention comprises a center differential with l1r1J5 for torque splitting and a second planetary gear mechanism, and a first switching clutch is provided between the second planetary gear mechanism and the front wheel drive shaft. A second switching clutch is provided between the first and second planetary gear mechanisms and the rear wheel drive shaft, and a gear mechanism is provided between the front wheel drive shaft and the rear wheel drive shaft for idle rotation. A viscous coupling for prevention is provided, and the first and second switching clutches are linked by a single switching lever to switch between five stages, resulting in front-wheel drive. Five different drive states can be selected: front-side four-wheel drive, direct-coupled four-wheel drive, rear-side four-wheel drive, and rear-wheel drive.

[For production]

Based on the above configuration, the first and second
When the switching clutch is switched in five stages, in position E, 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 addition, at position (3), Ml and the second planetary gear mechanism are switched to a path that increases the front torque, resulting in a four-wheel drive state closer to the front wheels. Further, in position (3), the front and first wheel side drive shafts are directly connected via the first and second planetary gear mechanisms, resulting in a directly connected four-wheel drive state. Furthermore, in position (2), the first and second planetary gear mechanisms are switched to a path that increases the rear torque, resulting in a four-wheel drive state closer to the rear wheels. At position V, the front wheel drive shaft is disconnected from the second planetary gear mechanism and becomes free, resulting in a rear wheel drive state. Also, position 1. In ff, TV and V,
The viscous coupling is in operation, and when one wheel slips, it increases the drive torque of the other wheel in accordance with the resulting rotational difference between the front and rear drive shafts to recover from the slip state. In this manner, according to the present invention, it is possible to select the optimum driving state depending on various road surfaces, driving purpose, or preference.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In FIG. 1, reference numeral 1 denotes an input shaft to which a driving torque T from the transmission is input. 2 is a front wheel side drive shaft rotatably arranged within the input shaft 1, 3 is a rear wheel side drive shaft, and 4 is a first planetary gear mechanism, which includes a plurality of M star binions 4a, a sun gear 4b, and a hollow space integrated therewith. It is composed of a shaft 4C. , 5 is a second planetary gear mechanism, which includes a plurality of planetary pinions 5a, a sun gear 5b integrated with a hollow shaft 5e, and a ring gear 5 integrated with a hollow shaft 5d.
It is composed of c. 6 is a planetary pinion 4a, 4
A rotary shaft 7 connecting the input shaft 1 is a carrier fixed to the input shaft 1, and drives both planetary pinions 4a and 5a to revolve through the rotary shaft 6. 8 is a first switching clutch, which has internal teeth 8a.
Selector sleeve 8a with 1.8at, 8as
and a gear 8b that can be engaged in 3 positions and is fixed to the hollow shaft 5d.
i, a 1-position engagement gear 8b, a 1-position engagement gear 8b fixed to the hollow shaft 5e, a 3-position engagement gear 8b4, and a gear 8b4 fixed to the front wheel side drive shaft 2. and a gear 8b that can be engaged in four positions. 9 is a second switching clutch with internal teeth 9a1.9a, 9a. a selector sleeve 9a having a selector sleeve 9a, a 1-position engagement gear 9b1 rotatably supported on the rear-wheel drive shaft 3, a 3-position engagement gear 9b, and a gear 9b fixed to the rear-wheel drive shaft 3 It is composed of a gear 9bi that can be engaged in 5 positions. 10 is a gear fixed to the hollow shaft 4C, 11 is a gear 9b1
With gears and teeth! It meshes with l110. 12 is a gear fixed to the hollow shaft 5d, 13 is a gear 9b,
This gear is integrated with the gear 12 and meshes with the gear 12. Reference numeral 14 denotes a viscous coupling, which is made up of a housing 14a rotatably supported on the rear wheel drive shaft 3, a plurality of plates on the rear wheel drive shaft 3, and a plate on the housing 14a side interlaced with each other. A high viscosity fluid is sealed inside the housing 14b, and when a rotation difference occurs between the housing 14a and the hub 14b, a corresponding coupling torque is generated. 15 is a gear fixed to the front wheel drive shaft 2;
A gear 16 is integrated with the viscous coupling 14 and meshes with the gear 15. 17 is the propeller shaft, 18 is the rear differential, 1
9 is the selector lever, its fork Tea, 19
b engage with selector sleeves Ila and 9a, respectively. 20 is a switching lever that can set five positions from position E to position V. Next, regarding the operation of the four-wheel drive system configured as described above, the first section shown in FIG. This will be explained with reference to the stopped state at each position of the second switching clutch 8.9 and the distribution state of the front torque TF and rear torque TR shown in FIG. First, when the switching lever 20 is set to position E, the selector sleeves 8a and 9a of the first and second switching clutches 8 and 9 are moved to the leftmost position by the selector lever 19, as shown in FIG. , in the first switching clutch 8, the tooth 8a1, the gear 8b1, the tooth 8a, and the gear 8b1. Since the teeth 8a and the gear 8b are engaged with each other, and the front drive shaft 2 and the hollow shafts 5d and 5e are integrally connected, the planetary motion of the second planetary gear mechanism 5 is prevented. On the other hand, in the second switching clutch 9, the teeth 9
Although it engages with the a2 gear 9b2, the teeth 9a1.9a3
and the gears 91)t and 9b are disengaged, so
The connection between both gears 11 and 13 and the rear wheel drive shaft 3 is released, and the rear torque TR becomes zero. All of the driving torque T from the input shaft 1 is transferred from the carrier 7 to the second planetary gear mechanism 5. Front torque TF passes through the first switching clutch 8 to the front wheel drive shaft 2.
(Transmitted as TF = T>, the front wheels are driven, and the stability at high speeds is improved. In this driving condition, for example, if the front wheels slip and the front drive shaft 2 spins at high speed, the rear wheels drive the front wheels. Since a rotation difference occurs between the drive shaft 3 and the drive shaft 3, the viscous coupling 14 applies torque corresponding to the rotation difference to the rear drive shaft 3 to temporarily shift from the front wheel drive state to the four wheel drive state. Then, when the switching lever 20 is switched to position 2, the first and @2 switching clutches 8.9 become stopped as shown in FIG. 2 planetary gear mechanism 5
The sun gear 5b becomes free, and the front drive shaft 2 becomes the second
is connected to the ring gear 5c of the planetary gear mechanism 5,
The rear drive shaft 3 is connected to the sun gear 4b of the first planetary gear mechanism 4 via gears 11 and 10. In this state, the driving torque T input from the input shaft 1 drives both planetary pinions 4a and 5a to revolve through the carrier 7,
The front torque Tr- is transferred to the front wheel side drive shaft 2 via the planetary pinion 5a, ring gear 5c, and first switching clutch 8, while the planetary pinion, t-ton 4a, +j-nk t4b
, Gear 10.11° The rear torque TR is transmitted to the rear drive shaft 3 via the second switching clutch 9, but due to the gear ratio of the sun gear 4b and the ring gear 5c, the torque is transmitted to the four front wheels where TF>TR. It becomes a driving state. Note that even in this driving state, the viscous coupling 14 functions in the same manner. Furthermore, when the switching lever 20 is switched to position ■,
il and the second switching clutch 8.9 are in a stopped state as shown in FIG.
, 5e to prevent planetary movement of the second planetary gear mechanism 5. On the other hand, the rear wheel side drive shaft 3 is the gear 1
3.12 to the hollow shaft 5d, the drive torque T from the input shaft 1 rotates the second planetary gear mechanism 5 integrally through the carrier 7, and the gear 12.1
3, and is transmitted to the front and rear drive shafts 2.3, respectively, resulting in a direct four-wheel drive state of TF #TR, improving the driving ability on rough roads. Furthermore, when the switching lever 20 is switched to position ■, the @1 and second switching clutches 8.9 are switched to the position shown in FIG.
), and the front wheel drive shaft 2 is in the engaged state as shown in FIG.
The rear wheel side drive shaft 3 is connected to the sun gear 5b of the planetary gear mechanism 5, and the gears 13, 12, . The first planetary gear mechanism 4 is connected to the ring gear 5c via the hollow shaft 5d.
will be free. Therefore, the driving torque from input shaft 1 is T depending on the gear ratio of sun gear 5b and ring gear 5C.
F<TR, the front torque TF is sent to the front drive shaft 2 via the sun gear 5b and the first switching clutch 8, and the rear torque TR is sent to the ring gear 5c, gears 12, 13, .
The signals are transmitted to the rear wheel drive shafts 3 via the second switching clutch 9, resulting in a four-wheel drive state closer to the rear wheels. In this driving state, turning performance and starting performance are improved. In this case as well, the viscous coupling 14 functions in the same manner. When the switching lever 20 is switched to position V, the first and second switching clutches 8.9 are engaged as shown in FIG. The connection is released and it becomes free, and the second
The planetary gear mechanism 5 includes a sun gear 5b and a ring gear 5.
C is integrally connected and its planetary motion is prevented. Therefore, all of the drive torque T input from the input shaft 1 is transferred to the second planetary gear mechanism 5. Gear 12.13. The rear torque TR (TR-T) is transmitted to the rear wheel drive shaft 3 through the second switching clutch 9, resulting in a rear wheel drive state. Note that even in this driving state, the viscous coupling 14 functions in the same way, and even if the rear wheels slip, it is possible to quickly escape from the slip state. In the above embodiment, the first and second switching clutches 8.9 are switched by manual operation of the switching lever 20, but they may be operated electrically or pneumatically.

【Effect of the invention】

As is clear from the above description, according to the four-wheel drive system of the present invention, two sets of planetary gear mechanisms for torque splitting are used as the center differential, and the first and second switching clutches are operated by operating one switching lever. Front-wheel drive, four-wheel drive with front wheels switched in conjunction with each other in five stages, depending on driving conditions or preference. Five different drive states can be selected at will: direct 4-wheel drive, rear-side 4-wheel drive, and rear-wheel drive, and this is combined with a viscous coupling to improve maneuverability, stability, starting performance, running performance, and This has the effect of improving drivability on rough roads.

[Brief explanation of the drawing]

1 to 3 are diagrams showing one embodiment of the present invention, and FIG. 1 is a skeleton diagram showing the configuration of a four-wheel drive device;
FIG. 2 is a diagram showing the engaged state of the first and second switching clutches, and FIG. 3 is a diagram showing the drive torque distribution. 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... First switching clutch, 9... Second switching clutch, 14... Viscous coupling, 20... Switching lever. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Jundo Nobu Kobashi Patent Attorney Susumu Murai0] -0

Claims (1)

[Claims] The center differential is the first and second one for torque splitting.
a first switching clutch between the second planetary gear mechanism and the front wheel drive shaft, and a second switching clutch between the first and second planetary gear mechanisms and the rear wheel drive shaft. A viscous coupling for preventing slippage is disposed between the front wheel drive shaft and the rear wheel drive shaft via a gear mechanism, and the first and second switching clutches are connected to the front wheel drive shaft and the rear wheel drive shaft. By switching in 5 stages in conjunction with the switching lever, you can select from 5 different drive states: front wheel drive, 4 wheel drive near the front, direct 4 wheel drive, 4 wheel drive near the rear, and rear wheel drive. A four-wheel drive device that is characterized by: