JPH0764212B2 - 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 front diff device that is configured to transmit power from a transfer shaft that is arranged in parallel to a transmission output shaft to a front wheel and a rear drive shaft that is configured to transmit power to rear wheels. A four-wheel drive device for transmitting, a planetary gear device as a center differential device, which is arranged coaxially with the transfer shaft, a carrier is connected to the transfer shaft, and a ring gear is transmitted to the rear drive shaft, and the transfer device. A hub arranged to be coaxial with the shaft, coupled to a sun gear of the planetary gear device, a housing coupled to the ring gear, and a hub having a viscous coupling having a differential limiting function, which is configured to be transmitted to the front differential device. , The transfer shaft and the viscous having a connecting position and a disconnecting position corresponding to the lever operation. Characterized by comprising a dog clutch to connecting and disconnecting a hub Ppuringu.

[Action]

In the present invention employing such means, when the dog clutch is lever-operated to the connecting position, the transfer shaft and the hub of the viscous coupling are connected. Therefore, in the planetary gear device as the center differential device, the carrier and the sun gear are integrated through the transfer shaft and the hub of the viscous coupling into a diff lock state, and the power is transmitted from the sun gear to the front differential device through the hub. In addition, the direct drive four-wheel drive traveling mode in which power is transmitted from the ring gear directly to the rear drive shaft is selected. Also, when the dog clutch is lever-operated to the disengaged position, the connection between the transfer shaft and the hub of the viscous coupling is disengaged, and the planetary gear system is able to make a differential between the sun gear and the ring gear, resulting in a diff locked state. Is released. Therefore, the planetary gear device functions as a center differential device while transmitting power from the sun gear to the front differential device via the hub and directly transmitting power from the ring gear to the rear drive shaft.
The wheel drive traveling mode is selected. At this time, the differential between the front differential device and the rear drive shaft is limited by a predetermined amount or more in accordance with the differential limiting function of the viscous coupling provided between the sun gear and the ring 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. Here, the transfer device 5 includes a transfer shaft 27 which is integrally coupled with a transfer gear 26 which meshes with the gear 23 and which is installed in the left-right direction of the vehicle body, and 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 pair of dog clutches 50 for switching a plurality of traveling modes are 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 is arranged coaxially with the transfer shaft 27. And this planetary gear device 40
The carrier 44 is connected to the transfer shaft 27, the ring gear 42 is transmitted to the rear drive shaft 29 via the pair of bevel gears 28, and is further transmitted to the rear wheels via the propeller shaft 30 and the like. 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 arranged coaxially with the transfer shaft 27 similarly to the planetary gear device 40, the hub 46 is integrally coupled to the sun gear 41 of the planetary gear device 40, and the housing 47 is integrally coupled to the ring gear 42 of the planetary gear device 40. At the same time, the hub 46 is configured to be transmitted to the differential device 24 of the front differential device 4 via the gears 31 and 32. The dog clutch 50 has a center differential with differential limitation.
It is for switching between 4WD and front and rear wheel direct connection F / R direct connection 4WD, and hub 46 of transfer shaft 27 and viscous coupling 45.
4WD position directly connected to F / R as a connection position for connecting and
2 with 4WD position as a disconnection position that disconnects both
Position along the transfer axis 27,
The sleeve 52 always meshes with the hub 51 integral with the 27. The teeth 52a of the sleeve 52 mesh with the splines 46a of the hub 46 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 in which two positions with the R direct connection 4WD are linearly 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 transfer shaft 27 via the output gear 22, the gear 23, and the transfer gear 26, and the transfer shaft 27
Input to the carrier 44 of the planetary gear unit 40. Therefore, use the select lever to move the rail 35 to the right F / R.
When operated to the direct coupling 4WD position, the teeth 52a of the sleeve 52 of the mesh clutch 50 mesh with the splines 46a of the hub 46 of the viscous coupling 45 as shown in the figure, so that the transfer shaft 27 and the hub 46 are connected. Therefore, in the planetary gear unit 40, the carrier 44 and the sun gear 41 are
27 and the viscous coupling 45 are integrated via the hub 46 to establish a diff lock state. Therefore, in this case, the power of the transmission output shaft 11 that is input to the carrier 44 of the planetary gear device 40 in the diff-lock state via the transfer shaft 27 is changed from the sun gear 41 of the planetary gear device 40 to the hub 46 of the viscous coupling 45 and the gear 31. ,
It is transmitted to the front wheels via the gear 32, the differential device 24 of the front differential device 4, the axle 25, etc., and is transmitted from the ring gear 42 to the rear wheels via the pair of bevel gears 28, the rear drive shaft 29, the propeller shaft 30, etc. 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 is operated to move the rail 35 to the left 4WD position, the meshing clutch 50 disengages the teeth 52a from the spline 46a of the hub 46 of the viscous coupling 45 due to the leftward movement of the sleeve 52, and the transfer shaft. The connection between 27 and the hub 46 is cut off. Therefore, the planetary gear device 40 can differentially operate the sun gear 41 and the ring gear 42, the differential lock state is released, and the planetary gear device 40 functions as a center differential device. Therefore, in this case, the transmission output shaft input to the carrier 44 of the planetary gear unit 40 via the transfer shaft 27.
The power of 11 is transmitted from the small-diameter sun gear 41 to the front wheels via the hub 46 of the viscous coupling 45, the gear 31, the gear 32, the differential device 24 of the front differential device 4, the axle 25, etc. Is transmitted from the ring gear 42 to the rear wheels via a pair of bevel gears 28, rear drive shaft 29, propeller shaft 30, etc., and thus rear wheel torque TR is larger than front wheel torque TF. It becomes a mode. In the four-wheel drive mode with the center differential, the viscous coupling 45 interposed between the sun gear 41 and the ring gear 42 of the planetary gear unit 40 places the sun gear 41 and the ring gear 42 in accordance with the differential limiting function. The differential above a certain amount is limited, and accordingly, the differential between the differential 24 of the front differential device 4 and the rear drive shaft 29 is limited to a predetermined amount or less. That is, when the vehicle normally turns, 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 rear drive. When the shaft 29 and the differential are more than a predetermined amount, the differential device 24 and the rear drive shaft 2 are engaged by the engagement action of the plates 48 and 49 of the viscous coupling 45.
Since the differential with 9 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 in the differential lock state and the direct connection 4 for transmitting power to the front differential device and the rear drive shaft.
When the wheel drive traveling mode is selected and the dog clutch is lever-operated to the disengaged position, the planetary gear device functions as a center differential device while transmitting power to the front differential device and the rear drive shaft. Is selected, and two types of four-wheel drive traveling modes are available: a direct-coupled four-wheel drive traveling mode that excels in running on rough roads and a four-wheel drive traveling mode with a center differential that provides smooth turning performance. Can be selected. Then, when the direct-coupled four-wheel drive traveling mode is selected, the torque of the transmission output shaft is distributed from the transfer shaft to the front differential device and the rear drive shaft through the sun gear and ring gear of the planetary gear device in the differential lock state in substantially equal parts. When the 4-wheel drive with center differential drive mode is selected, the torque of the transmission output shaft is small in the front differential device via the sun gear and ring gear of the planetary gear device that is in a state of being differential from the transfer shaft, and it is largely uneven in the rear drive shaft. Therefore, it is possible to obtain a running performance in which the front and rear wheels have a substantially equal torque distribution and a running performance in which the rear wheels have a large torque distribution. Here, when the four-wheel drive mode with the center differential is selected, the differential between the sun gear and the ring gear of the planetary gear device is limited by a predetermined amount or more in accordance with the differential limiting function of the viscous coupling, and accordingly, the front differential is selected. Since the differential between the device and the rear drive shaft is limited to a predetermined amount or less,
It is possible to escape from a bad road. Also, because a viscous coupling is used for limiting the differential between the front differential device 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 ... Front differential device, 5 ... Transfer device, 11 ... Transmission output shaft, 27 ... Transfer shaft, 29 ... Rear drive shaft, 40 ... Planetary gear device, 41 ... Sun gear, 42 ... Ring gear, 44 ... Carrier, 45 ... Viscous Coupling, 46
… Hub, 47… Housing, 50… Interlocking clutch.

Claims (1)

[Claims] 1. A four-wheel drive system for appropriately transmitting power to a front differential device which is arranged to be transmitted in parallel with a transmission output shaft and is configured to be transmitted to a front wheel, and a rear drive shaft which is configured to be transmitted to rear wheels. And a planetary gear device as a center differential device, which is arranged coaxially with the transfer shaft, a carrier is connected to the transfer shaft, and a ring gear is configured to be transmitted to the rear drive shaft; and a planetary gear device coaxial with the transfer shaft. The hub is connected to the sun gear of the planetary gear device, the housing is connected to the ring gear, and the hub is connected to the front differential device and has a viscous coupling having a differential limiting function and a lever operation. The transfer shaft and the hub of the viscous coupling are connected with a connecting position and a disconnecting position. Four-wheel drive system, characterized in that a dog clutch to.