JPS601030A - Drive force transmission for four wheel drive car - Google Patents

Abstract

PURPOSE:To provide a compact clutch while reducing the difference of length between left and right drive shafts in a two and four wheel drive changing- over device by providing a wet type clutch radially inside a surface of action a ring gear. CONSTITUTION:A wet type clutch unit 30 is provided radially inside a gear section of a ring gear 10 meshing with an output drive gear 7 of a transmission 6 while an intermediate gear 12 is provided coaxial with the ring gear through a bearing 17 on the outer periphery of a cylindrical portion 11c extending leftward near the center of a differential case 11a at the left side of said unit 30. Thus, a hydraulic force acting on the interior of a cylinder 10a through oil paths 10b, 10c is controlled to control torque transmitted to the intermediate gear 12 from the ring gear 10. Thus, the difference of length between left and right drive shafts 21, 22 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power transmission device for a four-wheel drive vehicle with a horizontally mounted engine, and more particularly to a switching device between two-wheel drive and four-wheel drive. .

(Prior art) Automobiles drive by transmitting the output of the engine to the wheels via a transmission, etc., and usually drive by transmitting the drive power only to the front or rear wheels. However, when the Mazatu coefficient between the tires and the road surface is small, such as on sandy, wet, snowy roads, etc., the tires may slip and become unable to obtain sufficient driving force, making it impossible to drive. There are also so-called four-wheel drive vehicles in use that drive the rear wheels together to provide sufficient driving force even when driving on sandy terrain as described above.

In addition, it is very common for automobiles to be steered by turning either the front wheels or the rear wheels.When steering, the trajectory of the front wheels and the trajectory of the rear wheels are different, so the axle rotation of the front wheels and the rear wheels are different. The rotation of the axle on the wheel side is different. in this case,
In a two-wheel drive vehicle, the front wheel rotation system and rear wheel rotation system are separate, so there is no problem, but in a four-wheel drive vehicle, the front and rear wheels are connected via the power transmission system, so the above If such a difference in rotation occurs between the front and rear wheels, it will cause tire wear, braking, etc., so it is necessary to absorb this difference in rotation, and for this reason, various proposals have been made in the past.

First, the simplest method is to switch between two-wheel drive and four-wheel drive using a two-wheel to four-wheel switching device such as a dog clutch mechanism.
There is a proposal to make it possible to switch between wheel drive and wheel drive states. This is because four-wheel drive is required mainly when driving on rough roads and at low speeds, and since the difference in rotation between the front and rear wheels when steering at low speeds is small, it is absorbed by tire slip. This allows the vehicle to run in two-wheel drive at high speeds, where there is a large difference in rotation between the front and rear wheels.
First, there is a proposal to provide a so-called center differential device to absorb a rotation difference between the front and rear wheels when it occurs. Examples of center differential devices include those that transmit power to the front and rear axles via a planetary gear mechanism, as disclosed in Japanese Patent Application Laid-Open No. 57-186522,
As disclosed in No. 1, it has been proposed that a power transmission system connecting a front axle and a rear axle is provided with a wet clutch that can connect and disconnect the two.

When a planetary gear mechanism is used, the rotation difference between the front and rear wheels during steering can be adjusted by the planetary gears, and the torque transmitted to the front and rear wheels can be distributed at a predetermined ratio determined depending on the configuration of the planetary gears. However, since the load distribution between the front and rear wheels changes when the vehicle starts, brakes, or climbs the vehicle, or when the number of passengers changes, the torque distribution transmitted to the front and rear wheels cannot be changed accordingly. This allows the engine's output to be transmitted to the road surface without waste. In view of this point, a wet clutch is more advantageous. In other words, when using a wet clutch, the difference in rotation between the front and rear wheels during steering can be absorbed by sliding the wet clutch, and by controlling the transmission torque capacity of the wet clutch, the torque distribution ratio between the front and rear wheels can be adjusted as desired. Can be set. Furthermore, this wet clutch also functions as a two-wheel to four-wheel switching device by engaging and disengaging the clutch.

On the other hand, the power transmission system of automobiles (especially passenger cars) is front engine, rear drive type (so-called F-R
There are several types of cars, including the front engine, front-engine, and front-drive models (the so-called F/F model), but recently the F/F model has been increasing in number. In the case of the F-F type, there are many types of engine equipment in which the engine is placed parallel to the direction of travel, but there are also types of horizontal engine installation in which the engine is placed parallel to the axle because of its advantages such as eliminating the need for bevel gears. Many have been adopted. When the engine is placed horizontally, the engine and transmission must be housed in a relatively narrow space limited by the width of the vehicle, and there is a strong demand for the engine and transmission to be more compact.

When converting a FF vehicle with a horizontally mounted engine into a 4-wheel drive vehicle, and when using the above-mentioned wet clutch as a 2-wheel-4-wheel switching device and a center differential device, due to the need for compactness, it is necessary to connect the FF vehicle in series with the engine. A transmission is installed, and a ring gear integrated with the front wheel differential case is meshed with the output gear of this transmission to transmit the transmission output to the front wheels.A wet clutch is installed on the side of this ring gear, and the engine output transmitted to the ring gear is transmitted through the wet clutch. □Most of them are of the type that also transmits information to the rear wheels.

In horizontally mounted engine F and F four-wheel drive vehicles with this type of structure, the engine is larger than the transmission, so the position of the transmission's output gear is biased to either the left or right with respect to the center of the vehicle, and it is difficult to mesh with this output gear. The ring gear and the differential case integrated with it are also located off to one side from the center of the vehicle body. For this reason, the lengths of the drive shafts for driving left and right wheels that extend left and right through the differential gear in the differential case are different, which causes undesirable phenomena such as torque steer. From this point,
It is desirable to minimize the difference in the length of the left and right drive shafts, but in order to locate the differential gear device and wet clutch device in the center of the vehicle body, it is necessary to reduce the radial dimension to prevent interference with the engine. There is. For this reason, in a wet clutch device, the diameter of the clutch friction plate must be made smaller, and in order to obtain the same transmitted torque capacity compared to a large force, the number of friction plates must be increased or the surface pressure must be increased. However, increasing the number of friction plates makes it difficult to control slippage, while increasing the surface pressure accelerates the wear of the friction plates.

(Object of the Invention) In view of the above-mentioned problems, the present invention provides a method for using a wet clutch integrally with a front wheel differential gear device as a 2-wheel-4 wheel switching device and a center differential device in a transverse engine FF 4-wheel drive vehicle. The objective is to make this wet clutch device as compact as possible, move the differential gear closer to the center of the vehicle body, and reduce the difference in length between the left and right drive shafts.

(Structure of the Invention) The driving force transmission device of the present invention connects a transmission to a transverse engine via a clutch device or a torque converter device, and integrates an output drive gear of the transmission with a differential case of a front wheel differential device. A wet clutch device engages and disengages the ring gear from an intermediate gear that meshes with the formed ring gear to transmit the output of the transmission to the front axle, and also transmits drive to the rear axle rotatably supported by the differential case. It is arranged coaxially with the ring gear on the radially inner side of the engagement surface with the drive gear of the ring gear, and transmits the output of the transmission to the rear axle via the wet clutch and the intermediate gear. It is characterized by having a friction plate that rotates as two bodies, a friction plate that rotates integrally with the intermediate gear, and a piston that is disposed in a cylinder chamber formed in the differential case and engages and disengages both friction plates.

(Effects of the Invention) According to the present invention, the wet clutch device is disposed on the radially inner side of the meshing surface of the ring gear that meshes with the output drive gear of the transmission, so that the differential gear can be moved away from the center of the vehicle body. It is possible to prevent a large bias toward either the left or right side, to reduce the difference in the length of the left and right drive shafts, and to suppress the occurrence of torque steer, etc.

Furthermore, the difference in rotation between the front and rear wheels that occurs when steering during four-wheel drive driving can be absorbed by the slippage of the wet clutch, thereby preventing tire wear and braking, as well as preventing starting, braking, climbing, etc. When the load distribution between the front and rear wheels changes due to a change in the number of occupants, etc., the torque capacity of the wet clutch is controlled and the torque distribution transmitted to the front and rear wheels is changed accordingly to transmit engine output to the road surface without waste. I can do it.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The figure is a sectional view showing an example of a driving force transmission device according to the present invention.

A transmission 6 is connected via a torque converter 3 to the output shaft side of an engine 100 that is placed horizontally with respect to a vehicle body.

A drive plate 2 is fastened to the output shaft 1 of the engine 100, and the drive plate 2 is fastened to an impeller 3a of a torque converter 3, so that the output of the engine 100 is directly transmitted to the impeller 3a. The torque converter 3 consists of three elements: an impeller 3a, a stator 3b, a turbine 3C, and a one-way clutch 3d, and uses a well-known torque conversion function to transmit engine output to the turbine 3C as rotation and torque according to the load acting on the turbine 3C. It will be done. The turbine 3C is attached to a turbine knob 4 connected to the transmission input shaft 5 by a spline, and the engine output converted into torque by the torque converter 3 is transferred to the turbine 3.
C and the turbine hub 4C to the transmission 60 input shaft 5. The transmission 6 has a well-known planetary gear type transmission mechanism (not shown in detail), and after the input transmitted to the input shaft 5 is shifted according to the speed stage selected in the transmission 6, the input is transferred to the output drive gear 7. Output. The output drive gear 7 is a gear provided on the outer periphery of the input shaft 5 between the transmission 6 and the torque converter 30, and is rotatably attached around a fixed shaft 9 provided between the transmission 6 and the torque converter 3. It meshes with the idler gear 8. This idler gear 8 meshes with a ring gear 10 formed integrally with a differential case lla of a differential device 11 of the front axle, and the output of the transmission 6 is transmitted to the differential device 10 via an output drive gear 7, an idler gear 8, and a ring gear 10. The differential gear l in this differential device 11
The signal is distributed and transmitted to the left and right drive shirts 1-21 and 22 via the lb. A wet clutch device 30 is provided inside the gear portion of the ring gear 10 in the radial direction, and a bearing 17 is provided on the outer periphery of a cylindrical portion 11c extending to the left near the center of the differential case Ila on the left side of the ring gear 10 in the drawing. An intermediate gear 12 is rotatably attached coaxially with the ring gear, and power transmission between the ring gear 10 and the intermediate gear 12 is controlled by a wet clutch device 30.

The wet clutch 30 includes a plurality of internally toothed friction plates 14 that are spline-coupled to the nozzle pulley lja extending to the right in the drawing of the intermediate gear 100, and a plurality of externally toothed friction plates 13 that are spline-coupled to the inner peripheral portion of the ring gear 10. These friction plates 13 and 14 are arranged alternately one on top of the other in the axial direction, and are prevented from moving outward (to the left in the figure) by a snap ring 19 arranged on the inner periphery of the ring gear 10. Engineering/Dog rate 1
8 and a piston 15 inserted into a cylinder 10a formed on the inner right side of the tire 10. The cylinder 10a is connected to an oil passage 10b that communicates with the inside of the differential case, and an IOC. When oil pressure is supplied from the outside to the cylinder 10a through the oil passage 10c, the piston 15 is pushed to the left in the figure by this oil pressure. Therefore, the friction plates 13 and 15 held between the end plate 18 and the piston 150 are also pressed against each other, and the power of the ring gear 10 is transmitted to the intermediate gear 12 by the friction between them. Further, a return spring 16 is provided on the inner diameter side of the piston 15, and urges the piston 15 in a direction opposite to the pressing force caused by the hydraulic pressure. The biasing force in the case of noon is smaller than the hydraulic pressure, but when the oil pot does not act, it works to push the piston 15 back to the right and eliminate the pushing force acting on the friction plates 13, 14.・ .

In the wet clutch 30 configured as described above, the torque transmitted from the ring gear 10 to the intermediate gear 12 can be controlled by appropriately controlling the hydraulic pressure acting in the cylinder 10a via the oil passages 10b and 10c.

On the other hand, the intermediate gear 12 meshes with a driven gear 23 having an axis parallel to the axis of this gear, and a bevel gear 24 connected to this gear 23 is attached coaxially with this driven gear 23.

Further, a pinion gear 25 having a shaft perpendicular to the gear 24 and located approximately at the center of the vehicle body is meshed with the bevel gear 24, and driving force is transmitted from the pinion gear 25 to the rear wheels.

Therefore, the speed is changed by the torque converter 3 and the transmission 6 and transmitted to the link tires 10. Part of the output of the engine 100 is transmitted to the front wheels via the differential device 11, and the rest is transmitted to the front wheels via the differential gear 11. In this case, by controlling the hydraulic pressure acting on the cylinder 10aK, the difference in rotation between the front and rear wheels during steering can be compensated for by slipping the clutch. It is also possible to adjust the distribution of torque transmitted to the front and rear wheels in response to changes in the load distribution between the front and rear wheels, such as when starting.

Furthermore, since the wet clutch device 30 is disposed on the inner circumferential portion of the ring gear 10, the wet clutch 30 is disposed on the left side of the ring gear lO as in the conventional case, and the ring gear 10 and the differential device 11 are connected approximately in the axial direction. Compared to a case where the wet clutch is formed integrally at the same position, the leftward protrusion of the wet clutch is eliminated, making it more compact, and the differential gear center B approaches the vehicle body center A, reducing the rain center distance C. be able to. For this reason, the front wheel left and right drive shirts) 13.1
Since the difference in the lengths of 4 becomes smaller, problems such as torque steer are less likely to occur.

In addition, although the above example shows an example of a car having an automatic transmission with a torque converter, the driving force transmission device can also be used when using a manually operated transmission using a clutch instead of a torque converter. are exactly the same. however,
If you have an automatic transmission,
Hydraulic pressure for operating the wet clutch can be easily obtained, and existing sensors can be used to distribute torque according to changes in front and rear wheel loads when starting, etc. It is advantageous in that there are many

[Brief explanation of the drawing]

The figure is a sectional view showing an example of a driving force transmission device according to the present invention. 3... Torque converter 6... Transmission 7... Output drive gear 8... Eye Drag gear 10... Ring gear 11... Differential device 12...
Intermediate gear 13.14... Friction plate 15... Piss
tons

Claims (1)

[Claims] A front wheel that has a transmission connected to a horizontally placed engine via a clutch device or a torque converter device, and a ring gear that meshes with the output drive gear of this transmission, and transmits the driving force from this transmission to the front axle. a differential gear for the front wheels; an intermediate gear disposed on the side of the ring gear and rotatably supported by the differential case of the front wheel differential gear for transmitting driving force from the transmission to the rear axle; and the drive of the ring gear. a wet clutch device disposed coaxially with the ring gear on the radially inner side of the meshing surface with the gear; a friction plate in which the wet clutch device rotates integrally with the ring gear; a friction plate that rotates integrally with the intermediate gear; A driving force transmission device for a four-wheeled vehicle σ), comprising a piston that is disposed in a cylinder chamber formed in the differential case and engages and disengages both the friction plates.