JPH0764211B2 - 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. More specifically, it is a horizontal transaxle type four-wheel drive drive mode including a direct-coupled four-wheel drive drive mode and a differential limited four-wheel drive drive mode. The present invention relates to a four-wheel drive device capable of arbitrarily selecting a wheel drive traveling mode.

[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, in the present invention, it is possible to arbitrarily select two types of four-wheel drive traveling modes, that is, a direct-coupled four-wheel drive traveling mode and a four-wheel drive traveling mode with a center differential capable of limiting the differential, while having a simple structure. An object is to provide a 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 differential device for front wheels and a transfer shaft for rear wheels are arranged in parallel to a transmission output shaft, and the four-wheel drive device is arranged coaxially with the transfer shaft. And the carrier is configured to be transmitted to the transmission output shaft via a transfer gear, and the ring gear is configured to be transmitted to the front differential device.
A planetary gear device as a center differential device in which a sun gear is connected to the transfer shaft, and a hub that is arranged coaxially with the transfer shaft, a hub is connected to the sun gear via the transfer shaft, and a housing is connected to the ring gear. It is characterized by including a viscous coupling having a motion limiting function, and a meshing clutch having a connecting device and a disconnecting position corresponding to a lever operation and connecting and disconnecting the transfer gear and the transfer shaft.

[Action]

In the present invention employing such means, when the dog clutch is lever-operated to the connecting position, the transfer gear and the transfer shaft are connected. Therefore, in the planetary gear device as the center differential device, the carrier is integrated with the sun gear through the transfer gear and the transfer shaft to be in the differential lock state, and the direct-coupled four-wheel drive traveling mode is selected. Also, when the dog clutch is operated to the disengaged position by the lever, the connection between the transfer gear and the transfer shaft is disengaged, so that the planetary gear unit can differentially operate the ring gear and the sun gear, and the differential lock state is released. It Therefore, the four-wheel drive mode with the center differential in which the planetary gear device functions as the 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.

【Example】

An embodiment of the present invention will be specifically described below with reference to the drawings. Referring to the drawings, a transmission system of a four-wheel drive system according to an embodiment based on a transversely mounted transaxle type front engine / front drive (FF) vehicle will be described. Are horizontally arranged in the left-right direction, and the front differential device 4 and the transfer device 5 are sequentially arranged from the transmission 3 to the rear of the vehicle body. And transmission 3, front differential device 4 and transfer device 5
Is installed inside the clutch housing 6, the transmission case 7, and the extension case 8 to form a transaxle type. The transmission 3 is of a constant mesh type and meshes with the input shaft 10 from the clutch 2 and the output shaft 11 arranged in parallel therewith, for example, the first speed to the fifth speed (overdrive).
A pair of speed change gears 12 to 16 are provided.
By selectively operating the synchro mechanism 17 between the gears 13 and 13, the synchro mechanism 18 between the speed change gears 14 and 15, or the synchro mechanism 19 adjacent to the speed change gear 16, the first speed to the fifth speed Each forward gear up to high speed is obtained. Further, the reverse gear 20 integrated with the input shaft 10 is configured to mesh with the gear 21 on the sleeve side of the synchronizing mechanism 17 through an idler gear (not shown) to obtain the reverse gear. The front differential device 4 has a differential device 24 that rotatably supports a gear 23 that meshes with an output gear 22 of the transmission output shaft 11 and that is arranged concentrically with the gear 23. Connected to the left and right front wheels via axle 25. The transfer device 5 has a transfer shaft 27 that is rotatably supported by a transfer gear 26 that meshes with the gear 23 and that is installed in the lateral direction of the vehicle body.
A pair of bevel gears 28 to rear drive shaft 29, propeller shaft 3
It is later configured to transmit via 0, etc. Here, the transfer device 5 includes a set of planetary gear devices 40 having a function as a center differential device, a viscous coupling 45 having a differential limiting function, and a set of meshing members for switching to a plurality of traveling modes. A clutch 50 is provided. The planetary gear unit 40 includes a sun gear 41, a ring gear 42, a pinion gear 43 that meshes with both gears 41, 42, and a pinion gear.
It consists of a carrier 44 supporting 43 and a transfer shaft 27
It is placed coaxially with. And this planetary gear device
40, carrier 44 is transfer gear 26, sun gear 41
Are connected to the transfer shaft 27, respectively, and the ring gear 42 is connected to the front differential device 4 via the gears 31 and 32.
The differential 24 is configured for transmission. The viscous coupling 45 has a hub 46 and a housing 47, and a plate 48, 49 integral with either one between them.
Are alternately arranged and a highly viscous liquid is enclosed. When the rotation difference between the hub 46 and the housing 47 increases, the shearing resistance of the enclosed liquid causes an engagement action to increase the transmission torque. The viscous coupling 45 is installed coaxially with the transfer shaft 27, like the planetary gear unit 40.
The sun gear 41 of the planetary gear device 40 is integrally connected to the housing 47, and the housing 47 is integrally connected to the ring gear 42 of the planetary gear device 40. The dog clutch 50 has a center differential with differential limitation.
It is for switching between 4WD and front / rear wheel direct connection F / R direct connection 4WD, and the transfer shaft 27 has two positions, a connection position for connecting and disconnecting the transfer gear 26 and the transfer shaft 27, and a disconnection position for disconnecting the connection between both. A sleeve 52 is always meshed with a hub 51 that is integrated with the transfer gear 26. The teeth 52a of the sleeve 52 mesh with the splines 27a of the transfer shaft 27 only at the connecting position, and the meshing is disengaged at the disconnecting position. Here, as the operation system of the dog clutch 50, 4WD and F.
A select lever (not shown) is provided whose two positions with the R direct connection 4WD are directly arranged in the left-right direction along the axial direction of the transfer shaft 27, and one rail 35 from this select lever is engaged with the clutch 50. Engaged with the sleeve 52 of the. Next, the operation of the four-wheel drive system of this embodiment constructed as described above will be described. First, the synchro mechanism 17,1 in the transmission 3 when the vehicle is traveling.
The gears for shifting 12 to 16,2 by synchronizing with 8,19 etc.
0, 21 and the like output the transmission output shaft 11 with five forward gears and one reverse gear. The power of the transmission output shaft 11 is input to the carrier 44 of the planetary gear unit 40 from the output gears 22 and 23 via the transfer gear 26 of the transfer unit 5. Therefore, use the select lever to move the rail 35 to the right F / R.
When operated to the direct connection 4WD position, the meshing clutch 50 connects the transfer gear 26 and the transfer shaft 27 by engaging the teeth 52a of the sleeve 52 with the splines 27a of the transfer shaft 27 as shown in the drawing. Therefore, the planetary gear device 40 is brought into a diff lock state by the carrier 44 being integrated with the sun gear 41 via the transfer gear 26 and the transfer shaft 27. Therefore, in this case, the power of the transmission output shaft 11 is input from the transfer gear 26 to the planetary gear unit 40 in the differential lock state, and the ring gear 42 is used to drive the gear 31, the gear 32, the differential unit 24 of the front differential unit 4, the axle 25, etc. Is transmitted to the front wheels via the sun gear 41 and the transfer shaft 2
7, a pair of bevel gears 28, rear drive shaft 29, propeller shaft 30
And the like, and the torque distributions of the front and rear wheels are substantially equal to each other. In this direct-coupling four-wheel drive traveling mode, starting performance and running performance on rough roads are maximized. Then, when the rail 35 is operated to the left 4WD position by the select lever, the dog clutch 50 moves the teeth 52a and the spline 27a of the transfer shaft 27 by the left movement of the sleeve 52.
And the transfer gear 26 and the transfer shaft 27 are disconnected from each other. Therefore, the differential gear state of the planetary gear device 40 is released, and the differential between the ring gear 42 and the sun gear 41 becomes possible, and the planetary gear device 40 functions as a center differential device. Therefore, in this case, power is transmitted from the large-diameter ring gear 42 of the planetary gear unit 40 to the front wheels via the differential unit 24, etc., and at the same time, the small-diameter sun gear 41 of the planetary gear unit 40 passes through the transfer shaft 27, etc. to the rear wheels. Thus, the front wheel torque TF becomes larger than the rear wheel torque TR, and the four-wheel drive mode with the center differential, which emphasizes the running property, is set. Then, in this four-wheel drive mode with center differential, the viscous coupling 45 interposed between the ring gear 42 and the sun gear 41 of the planetary gear device 40 is located between the ring gear 42 and the sun gear 41 depending on the differential limiting function. The differential above a certain amount is limited, and accordingly, the differential between the differential device 24 of the front differential device 4 and the transfer shaft 27 is limited to a predetermined amount or less. That is, during normal turning of the vehicle, the viscous coupling 45 becomes free to allow the difference in rotation between the front and rear wheels, so that smooth turning performance is exhibited, and wheel slip occurs, causing the differential 24 and the transfer shaft. When 27 and the differential are more than a predetermined amount, the differential device 24 and the transfer shaft 2 are caused by the engaging action of the plates 48 and 49 of the viscous coupling 45.
Since the differential with 7 is limited to a predetermined amount or less, it is possible to automatically escape from a bad road in this way. The operation of the select lever 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 connecting position, the planetary gear device as the center differential device is placed in the differential lock state and the direct-coupled four-wheel drive traveling mode is selected, and the dog clutch is operated. When the lever is operated to the shut-off position, the 4-wheel drive drive mode with a center differential that allows the planetary gear device to function as a center-diff drive is selected, and there is a direct drive 4-wheel drive drive mode with excellent running performance on rough roads and a smooth drive mode. It is possible to arbitrarily select two types of four-wheel drive traveling modes, that is, a four-wheel drive traveling mode with a center differential that provides excellent turning performance. Then, when the direct-coupled four-wheel drive traveling mode is selected, the torque of the transmission output shaft is distributed from the transfer gear to the front differential device and the transfer shaft through the ring gear and the sun gear of the planetary gear device in the differential lock state in a substantially equal manner. When the four-wheel drive with differential drive mode is selected, the torque of the transmission output shaft is large in the front differential device via the ring gear and the sun gear of the planetary gear device that is in a differential state from the transfer gear, and small in the transfer shaft, which is unevenly distributed. Since the torque is distributed to the front and rear wheels, it is possible to obtain a running performance in which the torque distribution to the front and rear wheels is substantially equal and a running performance in which the torque is largely distributed to the front 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 front differential is correspondingly limited. Since the differential between the device and the transfer shaft is limited to a predetermined amount or less,
It is possible to escape from a bad road. Also, since the viscous coupling is used for limiting the differential between the front differential device and the transfer 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. 3 ... Transmission, 4 ... Front differential device, 5 ... Transfer device, 11 ... Transmission output shaft, 26 ... Transfer gear, 27 ...
Transfer shaft, 29 ... Rear drive shaft, 40 ... Planetary gear, 41 ... Sun gear, 42 ... Ring gear, 44 ... Carrier,
45 ... Viscous coupling, 50 ... Matching clutch.

Claims (1)

[Claims] 1. A front differential device for front wheels and a transfer shaft for rear wheels are arranged in parallel to a transmission output shaft.
In the wheel drive device, the carrier is arranged coaxially with the transfer shaft, the carrier is configured to be transmitted to the transmission output shaft via a transfer gear, the ring gear is configured to be transmitted to the front differential device, and the sun gear is connected to the transfer shaft. A planetary gear device as a connected center differential device, and a viscous having a differential limiting function, which is arranged coaxially with the transfer shaft, a hub is connected to the sun gear via the transfer shaft, and a housing is connected to the ring gear. A four-wheel drive system comprising: a coupling; and a meshing clutch that has a connecting position and a disconnecting position corresponding to a lever operation and connects and disconnects the transfer gear and the transfer shaft.