JPH0764210B2 - 4-wheel drive - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive system for a vehicle such as an automobile. The present invention relates to a four-wheel drive device capable of arbitrarily selecting the three types of driving modes.

[Prior art]

Conventionally, regarding a four-wheel drive system, for example, the actual development of Sho 55-7242
There is one with a center differential shown in Japanese Patent No. 0. In this four-wheel drive system with a center differential, a diff lock mechanism is indispensable for exiting from a rough road, and it has been shown that a diff lock mechanism is used to hydraulically lock. Further, as a direct-coupling type four-wheel drive device, for example, the one using a viscous coupling is shown in Japanese Utility Model Publication No. 59-188731.

[Problems to be Solved by the Invention]

By the way, since the above-mentioned prior art can obtain only one of the driving modes of the center differential type and the direct coupling type, it is difficult to satisfy the traveling performance when the road condition is bad. Further, in the former four-wheel drive system with a center differential, there is a problem that the structure is complicated because the differential lock mechanism uses a hydraulic clutch. Therefore, the present invention has three types of traveling modes such as a direct-coupling four-wheel drive traveling mode, a center-differential four-wheel drive traveling mode capable of differentially limiting, and a rear-wheel drive traveling mode, while having a simple structure. An object is to provide a selectable four-wheel drive device.

[Means for Solving the Problems]

As a means for achieving this object, the present invention provides a four-wheel drive system in which a front drive shaft to the front wheels is coaxial with a transmission output shaft, and a rear drive shaft to the rear wheels is parallel to the transmission output shaft. A planetary gear device as a center differential device, which is arranged coaxially with the machine output shaft and the front drive shaft, has a carrier connected to the transmission output shaft, and has a ring gear transmitted to the rear drive shaft, and coaxially with the planetary gear device. The sun gear of the planetary gear unit has a hub, a hub has a viscous coupling having a differential limiting function in which a housing is connected to the ring gear, and first to third switching positions corresponding to lever operations. At the switching position, the sun gear, the housing, and the front drive shaft are connected to each other, and
In the switching position, the sun gear is connected to the front drive shaft, and in the third switching position, a meshing clutch connecting the sun gear and the housing is provided.

[Action]

In the present invention employing such means, when the dog clutch is lever-operated to the first switching position, the sun gear of the planetary gear device, the housing of the viscous coupling, and the front drive shaft are connected to each other. Therefore, the planetary gear device as the center differential device is
When the sun gear is integrated with the ring gear via the housing, the diff-lock state is established and the direct-coupled four-wheel drive traveling mode is selected. Further, when the dog clutch is lever-operated to the second switching position, the sun gear of the planetary gear device is disconnected from the housing and connected only to the front drive shaft.
Therefore, in the planetary gear unit, the differential lock state is released and the differential between the ring gear and the sun gear becomes possible,
A four-wheel drive mode with a center differential in which the planetary gear device functions as a center differential device is selected. At that time, the differential between the ring gear and the sun gear is limited by a predetermined amount or more in accordance with the differential limiting function of the viscous coupling provided between the ring gear and the sun gear. Further, when the dog clutch is lever-operated to the third switching position, the sun gear of the planetary gear device is disconnected from the front drive shaft and connected only to the housing. Therefore, in the planetary gear device, the sun gear and the ring gear are integrated into a diff lock state, and the viscous coupling loses the differential limiting function.Thus, the rear drive is performed via the ring gear of the planetary gear device diff locked by the transmission output shaft. The rear wheel drive mode in which only the shaft is driven is selected.

【Example】

An embodiment of the present invention will be specifically described below with reference to the drawings. A transmission system of a four-wheel drive system according to an embodiment of the present invention will be described. An engine 1, a clutch 2 and a transmission 4 are vertically arranged in a vehicle front-rear direction, and a front part is provided below the clutch 2 and the transmission 4. The diff device 16 is installed inside the transmission case to form a trans acrylic type. The transmission 4 is of a constant mesh type, in which the output shaft 5 is arranged in parallel to the input shaft 3 and the four shafts 3, 5 are meshed with each other, for example, the first speed to the fourth speed. Of the speed change gears 6 and 7 are selectively provided, and the synchronization mechanism 10 between the speed change gears 6 and 7 and the synchronization mechanism 11 between the speed change gears 8 and 9 are selectively operated, thereby Each forward shift speed from the fourth speed to the fourth speed is obtained. In addition, the reverse gear 12 provided on the input shaft 3 has a synchronizing mechanism.
The gear 13 on the sleeve side of 10 is meshed with an idler gear (not shown) to obtain a reverse gear. The transmission output shaft 5 is a hollow shaft, into which the front drive shaft 14 is inserted, and the drive pinion 15 formed at the front end of the front drive shaft 14 meshes with the crown gear 17 of the front differential device 16. It is configured to transmit to the front wheels. In addition, the transfer device 18 disposed at the rear of the transmission 4
In, the transmission output shaft 5 and the CFC drive shaft 14 inside thereof are arranged coaxially, and the rear drive shaft 19 is arranged in parallel above them. And this rear drive shaft 19
Is configured to be transmitted to the rear wheel side via a propeller shaft 20 and a rear differential device 21. The transfer device 18 is provided with a set of planetary gear device 30 having a function as a center differential device, a viscous coupling 40 having a differential limiting function, and a meshing clutch 45 for switching to a plurality of traveling modes. Has been. The planetary gear unit 30 includes a sun gear 31, a ring gear 32, a pinion gear 33 meshing with the two gears 31, 32, and a carrier 34 supporting the pinion gear 33, and is arranged coaxially with the transmission output shaft 5 and the front drive shaft 14. In this planetary gear device 30, a ring gear 32 is configured to be transmitted to a rear drive shaft 19 via a pair of gears 24 and 25, a carrier 34 is connected to a transmission output shaft 5, and a sun gear 31 is a mesh clutch 45. It can be connected to the front drive shaft 14 via. The viscous coupling 40 has a hub 41 and a housing 42, and plates 43, 44 that are integral with either one between them are provided.
Are alternately arranged and a highly viscous liquid is enclosed. When the rotation difference between the hub 41 and the housing 42 becomes large, the shearing resistance of the enclosed liquid causes the engaging action to increase the transmission torque. Therefore, in the viscous coupling 40, the hub 41 is integrally connected to the sun gear 31 of the planetary gear device 30, and the housing 42 is integrally connected to the ring gear 32 of the planetary gear device 30. The dog clutch 45 has 3 positions for switching 4WD with FF-direct connection 4WD-C.D & V.C. 4WD position with direct connection as the first switching position and 4WD position with C.D & V.C as the second switching position. , Having three switching positions of the FR position as the third switching position along the axial direction of the front drive shaft 14, and the viscous coupling
It is arranged behind 40. And this dog clutch 45
, The sleeve 47 meshes with the hub 46 that is integral with the sun gear 31,
In the direct connection 4WD position which is the first switching position, the teeth 4 of the sleeve 47 are
7a is a spline 42 of housing 42 that is integral with ring gear 32
The tooth 47b of the sleeve 47 meshes with the spline 14a of the front drive shaft 14 so that the sun gear 31 of the planetary gear unit 30, the housing 42 of the viscous coupling 40, and the front drive shaft 14 are mutually engaged. Connect to. In addition, in the 4WD position with C.D & V.C, which is the second switching position,
Only the tooth 47b of the sleeve 47 meshes with the spline 14a of the front drive shaft 14 to connect the sun gear 31 and the front drive shaft 14, and at the FR position, which is the third switching position,
Only the teeth 47a of the sleeve 47 are the splines 42a of the housing 42.
The sun gear 31 and the housing 42 are connected by meshing with. Here, with the C.D & V.C as the operating system of the dog clutch 45
4WD, direct connection 4WD, FR positions are linearly arranged in the front-rear direction along the axial direction of the front drive shaft 14
48 is provided, and one rail 49 from the select lever 48 engages with the sleeve 47 of the dog clutch 45. Next, the operation of the four-wheel drive system of this embodiment constructed as described above will be described. First, by operating the synchronizing mechanisms 10, 11 and the like in the transmission 4 when the vehicle is running, the transmission gears 6 to 9 and 12, 13
As a result, transmission power of four forward gears and one reverse gear is output to the transmission output shaft 5. The power of the transmission output shaft 5 is input to the carrier 34 of the planetary gear device 30 in the transfer device 18. Therefore, when the select lever 48 is operated to the intermediate direct connection 4DW position, the dog clutch 45 is engaged with the sleeve 47 as shown in the figure.
47a of the planetary gear device 30 and the housing 42 of the viscous coupling 40 and the front drive of the planetary gear device 30 by engaging the spline 42a of the housing 42 with the spline 42a of the housing 42 and the spline 14a of the sleeve 47 with the spline 14a of the front drive shaft 14. Connect the three with axis 14 to each other. For this reason,
In the planetary gear unit 30, the sun gear 31 is integrated with the ring gear 32 through the housing 42 to be in a diff lock state, and in this state, the sun gear 31 is connected to the front drive shaft 14. Therefore, in this case, the power of the transmission output shaft 5 is transmitted from the sun gear 31 of the planetary gear device 30 in the diff lock state to the front wheels via the front drive shaft 14, and at the same time from the ring gear 32 of the planetary gear device 30 to the gears 24, 25, rear. It is transmitted to the rear wheels via the drive shaft 19, and thus the direct-coupling four-wheel drive traveling mode is set in which the torque distributions of the front and rear wheels are substantially equal.
In this direct-coupling four-wheel drive traveling mode, starting performance and running performance on rough roads are maximized. Next, when the select lever 48 is operated to the front 4WD position with C & D.V.C, the meshing clutch 45 disengages the teeth 47a from the spline 42a of the housing 42 due to the forward movement of the sleeve 47 and the sleeve 47 of the sleeve 47. Only the tooth 47b meshes with the spline 14a of the front drive shaft 14 to connect the sun gear 31 and the front drive shaft 14. For this reason, the differential gear state of the planetary gear device 30 is released, the differential between the ring gear 32 and the sun gear 31 becomes possible, and the planetary gear device 30 functions as a center differential device. Therefore, in this case, power is transmitted from the large-diameter ring gear 32 of the planetary gear device 30 to the rear wheels via the gears 24, 25 and the rear drive shaft 19, and at the same time, the small-diameter sun gear 31 of the planetary gear device 30 to the viscous coupling 40. Hub 41,
The power is transmitted to the front wheels via the front drive shaft 14, and thus the four-wheel drive mode with the center differential in which the rear wheel torque TR is larger than the front wheel torque TF and the maneuverability is emphasized. In the four-wheel drive mode with the center differential, the viscous coupling 40 interposed between the ring gear 32 and the sun gear 31 of the planetary gear unit 30 places the ring gear 32 and the sun gear 31 in accordance with the differential limiting function. The differential above a certain amount is limited, and accordingly the differential between the rear drive shaft 19 and the front drive shaft 14 is limited to a predetermined amount or less. That is, during normal turning of the vehicle, the viscous coupling 40 becomes free to allow the difference in rotation between the front and rear wheels, so that smooth turning performance is exhibited, and axle slip occurs, causing front drive shaft 14 and rear drive. When the shaft 19 and the drive shaft 19 are different from each other by a predetermined amount or more, the engagement between the plates 43 and 44 of the viscous coupling 40 limits the differential between the front drive shaft 14 and the rear drive shaft 19 to a predetermined amount or less. Thus, it is possible to automatically escape from a bad road. Further, when the select lever 48 is operated to the rear FR position, the tooth 47b of the first dog clutch 45 is disengaged from the spline 14a of the front drive shaft 14 by the rearward movement of the sleeve 47, and only the tooth 47a is spline 42a of the housing 42. The sun gear 31 and the housing 42 are connected by meshing with. Therefore, in the planetary gear device 30, the sun gear 31 and the ring gear 32 are integrated to be in a diff-locked state, and the viscous coupling 40 loses the differential limiting function. Thus, the planetary gear device 30 diff-locked by the transmission output shaft 5 is The rear wheel drive traveling mode in which only the rear drive shaft 19 is driven from the ring gear 32 via the gears 24, 25 is set. The operation of the select lever 48 may be performed using an actuator such as air pressure or a motor.

【The invention's effect】

As described above, according to the present invention, when the dog clutch is lever-operated to the first switching position, the planetary gear device as the center differential device is placed in the differential lock state, and the direct drive four-wheel drive traveling mode is selected. When the lever is operated to the switching position, the four-wheel drive mode with center differential in which the planetary gear device functions as a center differential device is selected, and when the lever is operated to the third switching position, the planetary gear device is in the diff-locked state and the viscous The rear wheel drive mode is selected because the coupling loses the differential limiting function, and the direct-drive 4-wheel drive mode excels in running on rough roads and the center differential with 4 that provides smooth turning performance. It is possible to arbitrarily select three types of traveling modes, a wheel drive traveling mode and a rear wheel drive traveling mode. When the direct drive four-wheel drive traveling mode is selected, the torque of the transmission output shaft is distributed to the front drive shaft and the rear drive shaft through the sun gear and the ring gear of the planetary gear unit in the differential lock state, and the torque is distributed to the center drive with the center differential. When the four-wheel drive running mode is selected, the torque of the transmission output shaft is distributed to the front drive shaft via the sun gear and ring gear of the planetary gear unit in the differential state, which is small in the front drive shaft and largely distributed to the rear drive shaft in a non-uniform manner. When the wheel drive running mode is selected, the torque of the transmission output shaft is transmitted only to the rear drive shaft, which means that the torque distribution of the front and rear wheels is approximately even and the torque distribution of the rear wheels is large. It is possible to obtain the traveling performance in which the torque is transmitted only to the front and rear wheels. Here, when the four-wheel drive mode with the center differential is selected, the differential between the ring gear and the sun gear of the planetary gear device is limited by a predetermined amount or more according to the differential limiting function of the viscous coupling, and accordingly, the rear drive is performed. Since the differential between the shaft and the front drive shaft is limited to a predetermined amount or less, it is possible to escape from a bad road. Further, since the viscous coupling is used for limiting the differential between the front drive shaft and the rear drive shaft, the structure is simple.

[Brief description of drawings]

The drawings are skeleton diagrams showing an embodiment of a four-wheel drive system according to the present invention. 4 ... transmission, 5 ... transmission output shaft, 14 ... front drive shaft, 18 ... transfer device, 19 ... rear drive shaft, 30 ...
Planetary gear unit, 31 ... Sun gear, 32 ... Ring gear,
34 ... Carrier, 40 ... Viscous coupling, 45 ... Interlocking clutch.

Claims (1)

[Claims] 1. A four-wheel drive system in which a front drive shaft to the front wheels is arranged coaxially with a transmission output shaft and a rear drive shaft to the rear wheels is arranged in parallel to the transmission output shaft, wherein the transmission output shaft and the front drive are arranged. A planetary gear device as a center differential device, which is arranged coaxially with the shaft, has a carrier connected to the transmission output shaft, and has a ring gear transmitted to the rear drive shaft, and a planetary gear device coaxially arranged with the planetary gear device. The sun gear has a hub, the ring gear has a housing connected to the housing, and the housing has a viscous coupling having a differential limiting function, and first to third switching positions corresponding to lever operations.
In the first switching position, the sun gear, the housing, and the front drive shaft are connected together, in the second switching position, the sun gear and the front drive shaft are connected, and in the third switching position, the sun gear and the housing are connected. A four-wheel drive system comprising a dog clutch.