JPH0764209B2 - 4-wheel drive - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a four-wheel drive system for a vehicle such as an automobile, and more specifically, in a vertically installed transaxle type, a four-wheel drive drive mode with a direct connection, a four-wheel drive drive mode with a center differential capable of limiting differential, and a front-wheel drive drive mode. The present invention relates to a four-wheel drive device capable of arbitrarily selecting 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. In view of this, the present invention arbitrarily selects three types of traveling modes, that is, a direct-coupling four-wheel drive traveling mode, a center-differential four-wheel drive traveling mode capable of differentially limiting, and a front-wheel drive traveling mode, while having a simple structure. An object is to provide a possible four-wheel drive system.

[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 sun gear transmitted to the rear drive shaft, and a coaxial with the rear drive shaft. A viscous coupling having a differential limiting function, wherein the hub is connected to the rear drive shaft, and the housing is configured to be transmitted to an intermediate shaft coaxially arranged with the transmission output shaft and the front drive shaft. The ring gear of the planetary gear device is provided with three switching positions of a first connection position, a second connection position, and a cutoff position according to lever operation. A first meshing clutch that connects and disconnects the intermediate shaft; and a first meshing clutch that is interlocked with the first meshing clutch and is switched to three switching positions, and the first meshing clutch connects the ring gear and the intermediate shaft. When in the first connection position, the transmission output shaft, the front drive shaft, and the intermediate shaft are connected together, and when the first meshing clutch is in the second connection position where the ring gear and the intermediate shaft are connected, the intermediate shaft is formed. And a front drive shaft, and a second mesh clutch that connects the transmission output shaft and the front drive shaft when the first mesh clutch is in a disengagement position that disconnects the ring gear and the intermediate shaft. It is characterized by that.

[Action]

In the present invention employing such means, when the first dog clutch is lever-operated to the first connecting position, the ring gear and the intermediate shaft of the planetary gear device are connected, and at the same time, the second gear is engaged.
The transmission output shaft, the front drive shaft, and the intermediate shaft are connected to each other via a dog clutch. Therefore, in the planetary gear device as the center differential device, the ring gear is integrated with the carrier via the intermediate shaft and the transmission output shaft to be in the differential lock state, and the direct-coupling four-wheel drive traveling mode is selected. When the first dog clutch is lever-operated to the second connected position, the ring gear of the planetary gear device and the intermediate shaft are connected, and at the same time, the intermediate shaft and the front drive shaft are mutually connected via the second dog clutch. Connecting. Therefore, in the planetary gear unit, the ring gear is connected to the front drive shaft via the intermediate shaft to enable differential with the sun gear, and the planetary gear unit functions as a center differential unit. To be done. At this time, the differential between the front drive shaft and the rear drive shaft is limited by a predetermined amount or more depending on the differential limiting function of the viscous coupling provided between the intermediate shaft and the rear drive shaft. Further, when the lever of the first mesh clutch is operated to the disengaged position, the connection between the ring gear of the planetary gear device and the intermediate shaft is disconnected, and at the same time, the transmission output shaft and the front drive shaft are separated via the second mesh clutch. Connecting. Therefore, the planetary gear device loses its function as a center differential device because the ring gear can rotate freely, and the viscous coupling loses the differential limiting function because the intermediate shaft can rotate freely. A front-wheel drive traveling mode in which only the front drive shaft is driven by the shaft 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 transaxle 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 front 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 includes a set of planetary gear devices 30 having a function as a center differential device, a viscous coupling 40 having a differential limiting function, and a first dog clutch 45 for switching to a plurality of traveling modes. And a second dog clutch 50. 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 sun gear 31 is configured to be transmitted to a rear drive shaft 19 via a pair of gears 22 and 23, a carrier 34 is connected to the transmission output shaft 5, and a ring gear 32 is connected to the transmission output shaft. 5 and a front drive shaft 14 and an intermediate shaft 26 arranged coaxially therewith via a first dog clutch 45. The intermediate shaft 26 is connected to the second dog clutch 50.
It is possible to connect to the transmission output shaft 5 and the front drive shaft 14 via the. 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, the hub 41 of the viscous coupling 40 is the rear drive shaft on the sun gear 31 side.
The housing 42 is integrally connected to the intermediate shaft 26 on the ring gear 32 side through a pair of gears 24 and 25. The first dog clutch 45 is a FF-4WD switching three-position two-effect type, and has a direct connection 4WD position and a second connection position as a first connection position for connecting the ring gear 32 and the intermediate shaft 26 of the planetary gear device 30. 4WD position with C.D & V.C. and FF position as a disconnecting position for disconnecting the connection are provided along the axial direction of the transmission output shaft 5, and the hub 46 of the intermediate shaft 26 is sleeved. 47 always mesh. The teeth 47a of the sleeve 47 are connected to the ring gear 3 only at the first connecting position and the second connecting position.
It meshes with the second spline 32a and is disengaged at the cut-off position. The second dog clutch 50 is a lever operated in conjunction with the first dog clutch 45 FF-direct connection 4WD-CWD and 4WD with VC.
3 position switch for hub 51 of front drive shaft 14
The sleeve 52 always meshes with. And the first dog clutch
When 45 is the direct connection 4WD position which is the first connection position, the sleeve 5
The tooth 52a of 2 meshes with the spline 5a of the transmission output shaft 5, and the tooth 52b of the sleeve 52 meshes with the spline 26a of the intermediate shaft 26, whereby the transmission output shaft 5, the front drive shaft 14, and the intermediate shaft 26 Connect the three parties with each other. Further, when the first dog clutch 45 is in the second connecting position and the 4WD position with C.D & V.C, only the teeth 52b of the sleeve 52 are in the spline 2 of the intermediate shaft 26.
By meshing with 6a, the intermediate shaft 26 and the front drive shaft 14 are connected, and when the first meshing clutch 45 is in the FF position which is the disengaged position, only the tooth 52a of the sleeve 52 is the spline of the transmission output shaft 5. By meshing with 5a, the transmission output shaft 5 and the front drive shaft 14 are connected. Here, the first dog clutch 45 and the second dog clutch
As a control system for the 50, a select lever 48 is provided in which each position of 4WD with C.D & V.C, direct connection 4WD, and FF is linearly arranged in the front-rear direction along the axial direction of the transmission output shaft 5. One rail 49 from the lever 48 is connected to the first dog clutch 45.
And the sleeve 52 of the second dog clutch 50. 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. Then, the power of the transmission output shaft 5 is input to the carrier 34 of the planetary gear unit 30 in the transfer unit 18. Therefore, when the select lever 48 is operated to the intermediate direct-coupling 4WD position, the teeth 47a of the sleeve 47 mesh with the spline 32a of the ring gear 32 in the first dog clutch 45 as shown in the drawing.
The ring gear 32 of the planetary gear device 30 is connected to the intermediate shaft 26. At the same time, the second dog clutch 50 engages the teeth of the sleeve 52.
52a meshes with the spline 5a of the transmission output shaft 5, and the teeth 52b of the sleeve 52 meshes with the spline 26a of the intermediate shaft 26, so that the transmission output shaft 5, the front drive shaft 14, and the intermediate shaft
Connect the three with 26 to each other. Therefore, in the planetary gear unit 30, the ring gear 32 has the intermediate shaft 26 and the transmission output shaft 5
It becomes a diff-lock state by being integrated with the carrier 34 via the, and is connected to the front drive shaft 14 in this state. Therefore, in this case, the power of the transmission output shaft 5 is directly transmitted to the front wheels via the front drive shaft 14,
Direct transmission is transmitted from the sun gear 31 of the planetary gear unit 30 in the differential lock state to the rear wheels via the gears 22 and 23 and the rear drive shaft 19, and thus the torque distribution of the front and rear wheels is substantially equal.
Wheel drive mode is set. In this direct-coupling four-wheel drive traveling mode, starting performance and running performance on rough roads are maximized. Then, when the select lever 48 is operated to the front CWD & VWD 4WD position, the first meshing clutch 45 causes the ring gear 32 of the planetary gear unit 30 while the teeth 47a of the sleeve 47 mesh with the splines 32a of the ring gear 32. The connection state with the intermediate shaft 26 is maintained. On the other hand, in the second dog clutch 50, the tooth 42a and the spline 5a of the transmission output shaft 5 are disengaged by the forward movement of the sleeve 52, and only the tooth 52b of the sleeve 52 meshes with the spline 26a of the intermediate shaft 26. As a result, the intermediate shaft 26 and the front drive shaft 14 are connected. Therefore, the planetary gear device 30 can be differentially operated with the sun gear 31 by connecting the ring gear 32 to the front drive shaft 14 via the intermediate shaft 26, and the planetary gear device 3 functions as a center differential device. Therefore, in this case, power is transmitted from the small-diameter sun gear 31 of the planetary gear device 30 to the rear wheels via the gears 22 and 23, the rear drive shaft 19, and the hub 41 of the viscous coupling 40, and at the same time, the large diameter of the planetary gear device 30 is transmitted. Ring gear 32
Power is transmitted to the front wheels via the intermediate shaft 26 and the front drive shaft 14, and thus the front wheel torque TF becomes the four-wheel drive mode with a center diff that emphasizes the running property larger than the rear wheel torque TR. In the four-wheel drive mode with the center differential, the viscous coupling 40 provided between the intermediate shaft 26 and the rear drive shaft 19 via the gears 24, 25 drives the front drive according to the differential limiting function. The differential between the shaft 14 and the rear drive shaft 19 is limited to a predetermined amount or more. That is, when the vehicle normally turns, 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, wheel slip occurs, and the front drive shaft 14 and the rear drive are generated. If the shaft 19 and the differential are more than a predetermined amount,
Due to the engaging action of the plates 43, 44 of the viscous coupling 40, the differential between the front drive shaft 14 and the rear drive shaft 19 is limited to a predetermined amount or less, and thus it is possible to automatically escape from a bad road. Becomes Further, when the select lever 48 is operated to the rear FF position, the teeth 47a of the sleeve 47 are disengaged from the splines 32a of the ring gear 32, and the first meshing clutch 45 connects the ring gear 32 of the planetary gear device 30 and the intermediate shaft 26. Cut off.
On the other hand, in the second dog clutch 50, the tooth 52b is disengaged from the spline 26a of the intermediate shaft 26 by the backward movement of the sleeve 52, and the transmission output shaft 5 is connected only to the front drive shaft 14. Therefore, in the planetary gear unit 30, the ring gear 32 can freely rotate and loses the function as the center differential unit.
Further, the viscous coupling 40 loses the differential limiting function because the intermediate shaft 26 is allowed to freely rotate, and thus, the front drive shaft drive mode in which only the front drive shaft 14 is driven by the transmission output shaft 5 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 first dog clutch is lever-operated to the first connection position, the planetary gear device as the center differential device is in the differential lock state, and the direct coupling four-wheel drive traveling mode is selected. When the lever is operated to the second connection position, the planetary gear device functions as a center differential device, the four-wheel drive mode with the center differential is selected, and when the lever is operated to the cutoff position, the planetary gear device functions as the center differential device. The front-wheel drive mode is selected because the viscous coupling loses the differential limiting function, and a direct-coupled 4-wheel drive mode with excellent running performance on rough roads and smooth turning performance can be obtained. 4 wheel drive running mode with center differential,
It is possible to arbitrarily select three types of traveling modes, including the front-wheel drive traveling mode. When the direct-coupled 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 ring gear and the sun gear of the planetary gear unit in the differential lock state, and the center differential is provided. When the four-wheel drive traveling mode is selected, the torque of the transmission output shaft is distributed to the front drive shaft through the ring gear and the sun gear of the planetary gear device in the differential state, which is large and is distributed to the rear drive shaft in a small and non-uniform manner. When the drive running mode is selected, the torque of the transmission output shaft is transmitted only to the front drive shaft, and the running performance in which the torque distribution between the front and rear wheels is divided into approximately equal parts, and the running performance in which the torque distribution is largely distributed to the front wheels, It is possible to obtain the traveling performance in which the torque is transmitted only to the front wheels. Here, when the four-wheel drive mode with the center differential is selected, the front drive shaft and the rear drive shaft are restricted from being differential by a predetermined amount or more in accordance with the soft differential limiting function of the viscous coupling. It is possible to escape from. 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, 26 ... intermediate shaft, 30 ... planetary gear device, 31 ...
… Sun gear, 32 …… ring gear, 34 …… carrier, 40…
… Viscous coupling, 45 …… First mesh clutch,
50 …… Second mesh 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 sun gear transmitted to the rear drive shaft, and a hub arranged coaxially with the rear drive shaft. Is coupled to the rear drive shaft, and the housing has a viscous coupling having a differential limiting function, which is configured to be transmitted to an intermediate shaft coaxially arranged with the transmission output shaft and the front drive shaft, and a first member corresponding to a lever operation. A first connecting position, a second connecting position, and a disconnecting position, which have three switching positions to connect and disconnect the ring gear of the planetary gear device and the intermediate shaft. When the mesh clutch and the first mesh clutch are interlocked with each other and switched to three switching positions, and the first mesh clutch is in the first connection position connecting the ring gear and the intermediate shaft, the transmission output shaft And the front drive shaft and the intermediate shaft are connected to each other, and when the first meshing clutch is in the second connection position where the ring gear and the intermediate shaft are connected, the intermediate shaft and the front drive shaft are connected to each other, and A four-wheel drive system comprising: a second dog clutch that connects a transmission output shaft and a front drive shaft when the dog clutch is in a disconnection position that disconnects the ring gear and the intermediate shaft.