JPH0238141A - Power distribution device of four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To prevent generation of centrifugal oil pressures within an oil pressure room, in the title device which includes a wet type hydraulic multiple disk clutch, by ingeniously determining a position at which a clutch is disposed, and also making the device have such a constitution that a piston for pressing a clutch plate is fitted into a case which is an unmovable member. CONSTITUTION:This wet type hydraulic multiple disk clutch 7 which is included in the device stated in the title is interposed between a final gear 10 located inside a transversely disposed Trans-axle provided with a transfer and the diff.case 22 of a front wheel differential gear 4, and the diff.case 22 is also used in a clutch hub 7b. A piston 7f which provides pressing forces to the retainer plate 7d of this clutch 7 is slidably fitted into a case member 24, which is an unmovable member, and the piston is stopped from turning by a knock-pin 25. And the working end portion of the piston 7f, which portion is opposed to an oil pressure room 7g partitioned by a case member 24 and the piston 7f, is forced to abut against the retainer plate 7d as a release bearing 27 is interposed therebetween.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a power distribution device for a four-wheel drive vehicle equipped with a wet hydraulic multi-plate clutch that distributes power to front and rear wheels.

[Conventional technology]

As such a power distribution device for a four-wheel drive vehicle, the one described in Japanese Patent Application Laid-Open No. 146637/1983 is known. This is a wet-hydraulic multi-disc clutch that is interposed between the final gear in the horizontal transaxle and the transmission member to the front or rear wheels. The piston is housed inside the final gear and rotates therewith.

[Problem to be solved by the invention]

Therefore, centrifugal hydraulic pressure is generated in the hydraulic chamber for driving the hydraulic piston as the final gear rotates, and this is added to the control hydraulic pressure to act on the hydraulic piston. Therefore, in a wet hydraulic multi-disc clutch, the transmitted torque becomes larger than the set value corresponding to the control oil pressure, making it impossible to control the desired oil pressure.At the same time, when the vehicle reaches a medium to high speed range and the centrifugal oil pressure is large, As a torque limiter, the wet hydraulic multi-disc clutch can sufficiently absorb the internal circulating torque generated due to the difference in the effective diameter of the tires between the front and rear wheels due to the difference in the axle load distribution of the vehicle when driving straight or the movement of the center of gravity during acceleration. , deterioration of acceleration performance. There are disadvantages such as deterioration of fuel efficiency and generation of vibration and noise. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent the generation of centrifugal oil pressure in the hydraulic chamber of a wet hydraulic multi-disc clutch in order to eliminate these disadvantages, and to make the device configuration more compact.

[Means to solve the problem]

For this purpose, the present invention provides a four-wheel drive vehicle that is configured to transmit power to the front and rear wheels according to the pressure of hydraulic fluid to the wet-type hydraulic multi-disc clutch, in which the wet-hydraulic multi-disc clutch is installed in a transversely mounted transverse transformer with a transfer. It is arranged between the final gear in the axle and the differential case of the front wheel or rear wheel differential, and the hydraulic piston in this wet hydraulic multi-disc clutch is fixed to the case member of the trunk axle as a cylinder. The clutch is slidably fitted, and its working end opposite to the operating hydraulic chamber is pressed into contact via a bearing with a retainer plate fitted into the end of the clutch drum of the wet hydraulic multi-disc clutch. It is configured to press the clutch plate inside the drum.

[For production]

With this type of means, even if the clutch plate in the clutch drum rotates due to the rotation of the final gear, the hydraulic piston does not rotate because it is fitted inside the case of the stationary member, and therefore there is no space between the hydraulic piston and the case member of the transaxle. Centrifugal hydraulic pressure is not generated in the hydraulic chamber that is formed.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. FIG. 2 shows a power transmission system of a four-wheel drive vehicle equipped with a transverse transaxle with a transfer to which one embodiment is applied, with an engine 1 installed at the front of the vehicle body. A clutch 27 and a manual transmission 3 are disposed horizontally in the left-right direction, and behind them a front wheel differential device 4. Transfer device5. A propeller shaft 6 and a rear wheel differential 8 are arranged. Then, the power input from the engine 1 to the manual transmission 3 via the clutch 2 is suitably shifted and transferred from the output gear 9 to the final gear 10.
The power is input to the front wheel differential device 4 via the wet hydraulic multi-plate clutch 7, and the power is transmitted from there to the left and right front wheels. Further, a transfer gear 11 of the transfer device 5 meshes with the final gear 10, and a transfer shaft 21. The power from the transfer device 5, which is taken out rearward via a pair of bevel gears 12 for direction change, is input to the rear wheel differential device 8 via the propeller shaft 6 and the final gear 13, and is then transmitted to the left and right rear wheels. Power is transmitted to. Here, the wet hydraulic multi-disc clutch 7 includes an oil pump 14 connected to the electric motor or the crankshaft of the engine, as shown in FIG. Regulator valve 15i - Lancer clutch valve 16. Duty solenoid valve 17. A dedicated hydraulic control system having a pilot valve 18 supplies an appropriate control hydraulic pressure depending on the driving condition. In this hydraulic control system, a transfer clutch valve 16 whose duty pressure is controlled is interposed in a hydraulic circuit system whose pressure is regulated to a predetermined hydraulic pressure from an oil pump 14 by a regulator valve 15 and which reaches a wet hydraulic multi-disc clutch 7. A duty solenoid valve 17 for discharge control is inserted into a pilot pressure circuit system having a valve 18, and the duty solenoid valve 17 is adjusted to a desired duty pressure by a duty signal from a control unit 19. ,
The transfer clutch valve 16 is adapted to be adjusted to a desired clutch pressure. The relationship between the duty ratio, duty pressure, and clutch pressure is shown in FIG. 4. Wet hydraulic multi-plate clutch 7 equipped with such a hydraulic control system
is interposed between the final gear 10 in the transverse transaxle with transfer and the differential case 22 of the front wheel differential device 4, as shown in FIG. That is, the wet type hydraulic multi-disc clutch 7 has the differential case 22 also used as a clutch hub 7b, one end of the clutch drum 7a covering this is fitted and fixed to the final gear 10, and the other end of the clutch drum 7a is a window. It is rotatably supported by a case member 24 via a support plate 23 attached thereto. A plurality of ring-shaped clutch plates 7C are arranged on the inner periphery of the clutch drum 7a, and retainer plates 7d are provided at both ends.
On the other hand, on the outer periphery of the clutch hub 7b, a plurality of ring-shaped clutch discs 7e are alternately arranged and spline-fitted with the respective clutch plates 7C, and these clutch brakes 7c and retainer plates 7d. , and the clutch disk 7e constitute a multi-disc clutch. Here, the piston 7f that applies a pressing force to the retainer plate 7d has a ring shape, and is slidably fitted into the case member 24, which is an immovable member, and is prevented from rotating via a knock pin 25. , this case member 24
A hydraulic chamber 7g communicating with the transfer clutch valve 16 is formed between the two. The working end on the side opposite to the hydraulic chamber 7g is brought into contact with the retainer plate 7d via the release bearing 27 of angular contact. The release bearing 27 contacts the cylindrical housing portion 7h of the piston 7f because the outer race 27a is properly fitted therein, and the inner race 27b contacts the cylindrical housing portion 7h of the piston 7f as shown in FIG.
As shown in a), it abuts against the retainer plate 7d via a retainer portion 27c that passes through the window 23a of the support plate 23 and is spline-fitted to the inner periphery of the clutch drum 7a. In the four-wheel drive vehicle having the above configuration, the power transmitted from the engine 1 to the manual transmission 3 via the clutch 2 is appropriately shifted there, and the power is transferred from the final gear 10 via the wet hydraulic multi-disc clutch 7 on one side. The other one is input to the front wheel differential device 4, and the other is input to the rear wheel differential device 8 via the second wet hydraulic multi-disc clutch 28, thereby providing four-wheel drive. In this case, power is distributed between the rear wheels and the front wheels according to the transmission torque of the wet hydraulic multi-disc clutch 7. Then, this distribution ratio is changed from the PR state of 100% rear wheels and 0% front wheels by changing the clutch pressure according to the duty ratio signal from the control unit 19, and gradually increases the distribution to the front wheels.
It changes steplessly until it reaches a certain state. Therefore, the control unit 19 receives a throttle opening signal, a rear wheel rotation signal,
Electronic control by inputting various signals such as front wheel rotation signals and idle signals enables optimal front-rear power distribution according to vehicle driving conditions and road surface conditions, improving running stability and drivability. Can be done. During four-wheel drive driving, if there is a difference in the effective diameter of the tires between the front and rear wheels due to a difference in the axle load distribution between the front and rear wheels of the vehicle, sudden acceleration, or movement of the center of gravity when climbing, it is necessary to Rotation occurs. In such a case, wet hydraulic multi-plate clutch 7
acts as a torque limiter by being controlled to a desired clutch pressure, and the clutch plate 7c on the clutch drum 7a side and the clutch disc 7e on the clutch hub 7b side
This creates slippage between the wheels and absorbs the internal circulating torque caused by the difference in rotation between the front and rear wheels. Therefore, acceleration performance and fuel efficiency during four-wheel drive driving can be improved, and vibration noise of the drive system can be reduced. Now, looking at the behavior of the wet hydraulic multi-plate clutch 7 itself, as the final gear 10 rotates, the clutch drum 7
a, clutch plate 7c, and release bearing 2
Even if the inner race 27b of No. 7 rotates, the piston 7f
is slidably fitted into the case member 24, which is an immovable member, and is prevented from rotating by the case member 24. Therefore, in the hydraulic chamber 7g formed between the piston 7f and the case member 24, there is a Centrifugal hydraulic pressure is not generated, and no unnecessary pressing force is applied to the clutch plate 7C, etc. other than the pressing force due to the control hydraulic pressure. Therefore, the hydraulic pressure control of the hydraulic chamber 7g is accurate, and delicate hydraulic control is also possible. . Further, in the wet hydraulic multi-disc clutch 7, since the hydraulic chamber 7g is formed in the case member 24, the hydraulic chamber is provided in the rotating member,
Compared to the method of forming a hydraulic circuit using a seal ring between a stationary member and a rotating member, since a seal ring or the like is not required, there is less risk of pressure drop due to leakage, so the operating oil pressure of the wet hydraulic multi-disc clutch 7 can be increased. Good pressure and depressurization response. Since the hydraulic pressure has good responsiveness, it is possible to instantly change the power distribution ratio and control the behavior of the vehicle, such as when the front or rear wheels slip. Further, such a wet hydraulic multi-disc clutch 7 is disposed on the outer periphery of a differential device in a transverse transaxle with a transfer, so that the configuration of the transfer device becomes compact and flexibility is obtained in the layout of the power train. Note that in the above embodiments, the engine and transmission are located at the front side of the vehicle, and a wet hydraulic multi-disc clutch 7 is used.
It was based on a front engine/rear drive (PR) system that distributes power to the front wheels through a wet hydraulic multi-disc clutch, but the rear engine and transmission are located at the rear of the vehicle and power is distributed to the rear wheels through a wet hydraulic multi-plate clutch. It may also be based on an engine/front drive (RF). In addition, it can be applied not only to manual transmission vehicles but also to automatic transmission vehicles and vehicles with continuous cold transmission.

【Effect of the invention】

As explained above, according to the present invention, even if the clutch drum rotates due to the rotation of the final gear, the hydraulic piston does not rotate, and centrifugal hydraulic pressure is applied to the hydraulic chamber formed between the clutch drum and the case member of the transaxle. Therefore, no unnecessary pressing force is applied to the clutch plates, and the wet hydraulic multi-disc clutch distributes power to the front and rear wheels through appropriate transmission torque control according to the control oil pressure. It also sufficiently absorbs the internally circulating torque caused by the difference in rotation between the front and rear wheels, improving acceleration performance and fuel efficiency during four-wheel drive driving, as well as reducing vibration and noise in the drive system. . Since the wet hydraulic multi-plate clutch is interposed between the final gear and the differential case and disposed around the outer periphery of the differential device in the transverse transaxle equipped with a transfer, the structure of the transfer device can be made compact. In addition, since the hydraulic chamber is formed in the case member of the transaxle, which is a stationary member, there is less risk of pressure drop due to leakage in the hydraulic circuit compared to conventional examples in which the oil passage is formed on the rotating shaft, and the wet hydraulic multi-disc clutch is improves the responsiveness of increasing and decreasing hydraulic pressure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention.
a) is a sectional view taken along the line A-A in FIG. 1, FIG. 2 is a skeleton diagram of a transmission system of a four-wheel drive vehicle to which one embodiment is applied, and FIG. 3 is a hydraulic circuit diagram used in one embodiment; FIG. 4 is a characteristic diagram of duty pressure and clutch pressure. DESCRIPTION OF SYMBOLS 1... Engine, 2... Clutch, 3... Manual transmission, 4... Front wheel side differential, 5... Transfer device, 6... Propeller shaft, 7... Wet hydraulic pressure Multi-plate clutch, 7a...clutch drum, 7b...clutch hub, 7C...clutch plate, 7d...
Retainer plate, 7e...Clutch disc, 7f
...Piston, 7g...Hydraulic chamber, 7h...Cylinder-shaped housing part, 8...Rear wheel side differential device, 9...
Output gear, 10... Final gear, 11... Transfer gear, 11a... Collar, 12... Bevel gear, 13... Final gear, 14... Oil pump, 15... Regulator valve , 16... Transfer clutch valve, 17... Duty solenoid valve, 18... Pilot valve, 19...
Control unit, 21... Transfer ° axis, 22...
・Differential case, 23...Support plate, 23
a... Window, 24... Case member, 25... Dowel pin, 27... Release bearing, 27a... Outer race, 27b... Inner race, 27c...
Retainer part.

Claims (1)

[Claims] In a four-wheel drive vehicle configured to transmit power between the front and rear wheels according to the pressure of hydraulic oil applied to a wet hydraulic multi-disc clutch, the wet hydraulic multi-disc clutch is installed in a transverse transaxle with a transfer. The hydraulic piston in this wet hydraulic multi-disc clutch is placed between the final gear of the front wheel or the differential case of the front wheel or rear wheel differential, and the hydraulic piston in this wet hydraulic multi-disc clutch is fixed to the case member of the trunk axle as a cylinder and slides. The working end opposite to the operating hydraulic chamber is pressed into contact with the retainer plate fitted inside the end of the clutch drum of the wet hydraulic multi-disc clutch via a bearing, so that the working end is pressed into the clutch drum. A power distribution device for a four-wheel drive vehicle configured to press a clutch plate of a four-wheel drive vehicle.