JPH0237036A - Power distributor of four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To prevent generation of tight corner braking phenomenon by acting an inner circulation torque caused by rotational difference between front and rear wheels, with a required control oil pressure, to a wet type hydraulic multi- plate clutch. CONSTITUTION:A piston 7b giving compression, to a retainer plate 7d is formed in the form of a ring and slidably fitted to a case 24 being a fixed member, and also stopped its rotation through a knock pin 25. An oil pressure chamber 7g communicating with a transfer clutch valve 16a is formed between the case 24 and the piston 7b. A work end on the reverse side with respect to the chamber 7g is abutted against a retainer plate 7d through a release bearing 27.

Description

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

The present invention relates to a power distribution system for a 496II vehicle equipped with a wet hydraulic multi-plate clutch that distributes power to front and rear wheels.

[Conventional technology]

As a power distribution system for such a four-wheel drive vehicle, the fir-mounted engine type is described in Japanese Patent Application Laid-Open No. 61-155027, and the horizontal engine type is described in Japanese Patent Application Laid-Open No. 61-1.
The one described in Japanese Patent No. 46637 is conventionally known. The former has two wet hydraulic multi-plate clutches, one for front wheel drive and one for rear wheel drive, placed inside the case of a transfer device that branches and transmits power from the transmission output shaft to the front and rear wheels.
The latter has a wet hydraulic multi-plate clutch disposed between the final gear in the transaxle and the transfer shaft. Here, the hydraulic piston for pressing the clutch plate in these wet hydraulic multi-plate clutches is configured to rotate together with the clutch drum.

[Problem to be solved by the invention]

Since the hydraulic piston rotates together with the clutch drum, centrifugal hydraulic pressure is generated in the hydraulic chamber for driving the hydraulic piston as the clutch drum rotates, and this is added to the control hydraulic pressure and acts on the hydraulic piston. I come to do it. Therefore, in a wet hydraulic multi-disc clutch, the transmitted torque becomes larger than the set value corresponding to the control hydraulic pressure, making it impossible to control the desired hydraulic pressure, and when the vehicle reaches medium to high speed range.
When the centrifugal oil pressure is large, the wet hydraulic multi-plate clutch absorbs the internal circulating torque generated by 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. It cannot be absorbed sufficiently as a limiter, resulting in disadvantages such as deterioration of acceleration performance, deterioration of fuel efficiency, and generation of vibration and noise. Therefore, the present invention makes it possible to set the torque distribution to the front and rear wheels at an arbitrary ratio while having a compact configuration of the transfer device, and in order to solve the above-mentioned disadvantages, the generation of centrifugal hydraulic pressure in the hydraulic chamber of the wet hydraulic multi-disc clutch is achieved. The purpose is to prevent it from happening.

[Means to solve the problem]

For this purpose, the present invention provides a four-wheel drive vehicle configured to transmit power between the front and rear wheels according to the pressure of hydraulic oil to the wet-type hydraulic multi-disc clutch, in which the above-mentioned wet-hydraulic multi-disc clutch is installed horizontally with a transfer. 21 between the final gear in the transaxle and the differential case, and in the middle of the transfer transmission shaft! The hydraulic piston in these wet hydraulic multi-disc clutches is fixed to the case member of the transaxle as a cylinder so as to be slidably fitted therein, and is located on the side opposite to the hydraulic chamber for its operation. The working end of the wet hydraulic multi-disc clutch is fitted into the end of the clutch drum of the wet hydraulic multi-disc clutch or is pressed against the tener plate 1 via a bearing to press the clutch plate in the clutch drum. .

[For production]

With such means, even if the clutch plate in the clutch drum rotates due to the rotation of the final gear and transfer transmission shaft, the hydraulic piston in each wet hydraulic multi-disc clutch does not rotate, and these and the case member of the transaxle do not rotate. Centrifugal hydraulic pressure is not generated in each hydraulic chamber formed between the two. Power is then distributed to the front and rear wheels at an arbitrary ratio through hydraulic control of each wet hydraulic multi-disc clutch.

【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.
3 is placed horizontally in the left-right direction, and behind these is a front wheel differential device 4. Transfer device5. propeller shaft 6
, a rear wheel differential device 8 is arranged. The power inputted from the engine 1 to the manual transmission 3 via the clutch 2 is then appropriately varied 3M and transferred from the output gear 9 to the final gear 10 and then to the front wheel differential via the first wet hydraulic multi-disc clutch 7. The power is input to the device 4, from which power is transmitted 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 second wet hydraulic multi-plate clutch 28. 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 above-mentioned 1. Second two wet hydraulic multi-disc clutches 7
．． 28 is an oil pump 14 directly driven by an electric motor or an engine as shown in FIG. Regulator valve 15. Transfer clutch valve 16a, 1
6b, duty solenoid valves 17a, 17b
, and pilot valves 18a and 18b, appropriate control hydraulic pressure is supplied depending on the driving condition. This hydraulic control system has two wet hydraulic multi-plate clutches 7 and 28 whose pressure is regulated to a predetermined level by an oil pump 14 and a regulator valve 15.
Transfer clutch valves 16a and 16b each having duty pressure controlled are interposed in the hydraulic circuit system leading to the valves 1 (ia and 16b), and a pilot valve 18 is provided in the pilot pressure circuit system leading to these valves 1 (ia, 16b) for exhaust control. duty solenoid valve 17a,
17b was inserted. These duty solenoid valves 17a and 17b are connected to the control unit 1.
The transfer clutch valves 16a and 16b are individually adjusted to desired clutch pressures by adjusting the duty pressures to the desired duty pressures using the duty signals from the transfer clutch valves 16a and 16b. 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
．． 28 is interposed between the final gear 10 in the horizontal transaxle with transfer and the differential case 22 of the front wheel differential device 4, and between the transfer gear 11 and the transfer shaft 21. be done. That is, the first wet hydraulic multi-disc clutch 7 has the differential case 22 also used as the 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 fixed to the final gear 10. is rotatably supported by a case member 24 via a support plate 23 with a window. and clutch drum 7a
A plurality of ring-shaped clutch plates 7C are spline-fitted to the inner periphery of the clutch plate 7C along with retainer plates 7d 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 arranged alternately with the respective clutch plates 7c and are spline-fitted, and these clutch plates 7c, retainer plate 7d, and clutch disc 7e form a multi-plate structure. The clutch is configured. Here, the piston 7f that applies a pressing force to the retainer plate 7d has a ring shape, is slidably fitted into the case member 24 which is an immovable member, and has a knock pin 25.
A hydraulic chamber 7g communicating with the transfer clutch valve 16a is formed between the case member 24 and the transfer clutch valve 16a. The working end on the opposite side from the hydraulic chamber 7g is brought into contact with the retainer plate 1-76 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. On the other hand, in the second wet hydraulic multi-disc clutch 28, the clutch drum 28a is fitted and fixed to the collar portion 11a of the transfer gear 11 which is rotatably fitted to the transfer shaft 21, and the clutch hub 28b is connected to the transfer shaft 21 by a spline. They are mated. A plurality of ring-shaped clutch plates 28c are spline-fitted to the inner periphery of the clutch drum 28a together with retainer plates 28d at both ends, while a plurality of ring-shaped clutch discs 28e are fitted to the outer periphery of the clutch hub 28b. clutch plate 28c
The clutch plates 28c, the retainer plate 28d, and the clutch disc 28e constitute a multi-disc clutch. Similarly to the piston 7f, the ring-shaped piston 28f is slidably fitted into the case member 24 and is prevented from rotating via a knock pin 26. clutch hub 16b
A hydraulic chamber 289 is formed which communicates with the. The piston 28f has its working end opposite to the hydraulic chamber 28g in contact with an inner race 29a of the angular contact release bearing 29, and is connected to the retainer plate via its outer race 29b spline-fitted to the inner periphery of the clutch drum 28a. 28d. 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 transmitted from the final gear 10 to the first gear.
The other input is input to the front wheel differential device 4 via the wet type hydraulic multi-disc clutch 7, and the other is input to the rear wheel differential device 8 via the second wet type hydraulic multi-disc clutch 28, thereby producing four-wheel drive. . In this case, power is distributed to the front wheels and the rear wheels according to the transmission torque of each wet hydraulic multi-plate clutch 7.28. Then, this distribution ratio is changed from the FF state of 100% front wheels and 0% rear wheels by changing the clutch pressure according to the duty ratio signal from the control unit 19, and gradually increases the distribution on the rear wheels side, so that both front and rear wheels are directly connected to 4WD. After passing through the state, there is one more thing! to%2 Changes within the range until the rear wheels reach 100% FR state. Therefore, various signals such as a throttle opening signal, a rear wheel rotation signal, a front wheel rotation signal, a range signal, an idle signal, etc. are input to the control unit 19 for electronic control. & Appropriate front/rear power distribution is possible, improving running stability and drivability. When driving in four-wheel drive, 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, then A relative rotation occurs. In such a case, the wet hydraulic multi-plate clutch 7.28 works as a torque limiter by being controlled to a desired clutch pressure, and the clutch plate 7c, 28C on the clutch drum 7a or 28a side and the clutch disk on the clutch hub 7b, 28blFI 7e, 28e
Internal f! due to the difference in rotation between the front and rear wheels, causing slippage between the
iy! Absorb A torque. Therefore, acceleration performance and fuel efficiency during four-wheel drive driving can be improved, and vibration and noise in the drive system can be prevented. In addition, when a four-wheel drive vehicle turns the wheel significantly while driving, internal circulation torque is generated between the front and rear wheels due to the difference in turning radius between the front and rear wheels.
In particular, it is greatest at low-speed maximum steering, requiring more driving force than necessary, resulting in inconveniences such as engine stalling when parking the vehicle. In such a case, the first or second wet hydraulic multi-disc clutch 7.28 detects the above-mentioned longitudinal rotation speed and performs a pressure reduction groove to obtain a desired clutch pressure according to the rotation ratio or rotation difference. This problem is solved by causing slippage in the first or second wet hydraulic multi-plate clutch 7.28. Therefore, the tight corner braking phenomenon during turning can be avoided. Now, looking at the behavior of each wet hydraulic multi-plate clutch 7.28a, the final gear 10. Transfer gear 1
1, the clutch drums 7a, 28a, the clutch play) 7c, 28c, and the release bearing 27.
Even if the inner race 27b, outer race 29b, etc. of 29 rotate, the pistons H and 28f are stopped by the case member 24, which is an immovable member, and do not rotate. Therefore, no centrifugal oil pressure is generated in the hydraulic chambers 7j), 28i) formed between the pistons 7f, 28f and the case member 24, and no centrifugal oil pressure is generated in the clutch plays 7c, 28c, etc. other than the pressing force due to the control oil pressure. No unnecessary pressing force is applied. Therefore, the hydraulic pressure control of the hydraulic chambers 7g and 28g becomes accurate, and even delicate hydraulic control becomes possible. In addition, each wet hydraulic multi-plate clutch 7.28 has a hydraulic chamber 7i)
, 28jJ are formed in the case member 24, so there is no need for a seal ring, etc., compared to a system in which a hydraulic chamber is provided in the rotating member and a hydraulic circuit is formed using a seal ring between the stationary member and the rotating member. Wet hydraulic multi-disc clutch because there is less risk of pressure drop due to leakage 7.28
Good responsiveness to increasing and decreasing hydraulic pressure. 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 are not slipping. In addition, one of the wet hydraulic multi-disc clutches 7.28 is placed on the outer periphery of the differential device in the transverse transaxle with a transfer, making the configuration of the transfer device compact and providing greater freedom for the power train's layer I. or can be obtained. FIGS. 5 and 6 show another embodiment that differs from the previous embodiment only in the arrangement of the second wet hydraulic multi-disc clutch 28. FIG. Here, since the structure of the pond is the same as that of the previous embodiment, it will be explained using the same reference numerals.In the one shown in FIG. and transfer gear 11. Clutch drum 28a, clutch hub 28b, transfer shaft 2
It is configured to transmit power through one path. Also the 6th
In the one shown in the figure, the second wet hydraulic multi-disc clutch 28 is
It is interposed in the middle of the rear drive shafts f3a and 6b that are divided in the axial direction after the bevel gear 12 in the transfer device 5. In this other embodiment, since the second wet hydraulic multi-disc clutch 28 is interposed in the middle of the transfer transmission shaft, the same effects as in the first embodiment can be obtained. Although the embodiments described above are based on a front-engine four-wheel drive vehicle, they may also be constructed based on a rear-engine four-wheel drive vehicle. Furthermore, it is applicable not only to manual transmission vehicles but also to automatic transmission vehicles and vehicles with continuously variable transmissions.

【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 and the transfer transmission shaft, the hydraulic piston in each wet hydraulic multi-disc clutch does not rotate, and these and the case member of the transaxle do not rotate. Centrifugal hydraulic pressure is not generated in each hydraulic chamber formed between the two, so each wet hydraulic multi-disc clutch distributes power to the front and rear wheels at an arbitrary ratio using an appropriate transmission torque according to the control hydraulic pressure. In addition, by applying the desired control oil pressure to the wet hydraulic multi-disc clutch, internal circulating torque caused by the rotational difference between the front and rear wheels is sufficiently absorbed to avoid tight corner braking, improving acceleration performance and fuel efficiency. In addition to improving the performance, it also prevents the generation of vibration noise in the drive system. Each wet hydraulic multi-disc clutch is disposed within a transverse transaxle equipped with a transfer, and one wet hydraulic multi-disc clutch is disposed on the outer periphery of the differential case, so the configuration of the transfer device becomes 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 the conventional example where the oil passage is formed on the rotating shaft, and the wet hydraulic multi-disc clutch can be used. improves the responsiveness of 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, and FIGS. 5 and 6 are sectional views of essential parts showing other different embodiments. DESCRIPTION OF SYMBOLS 1...Engine, 2...Clutch, 3...Manual transmission, 4...Differential device for front wheels, 5...Transfer device, 6...Propeller shaft, 7...No. 1 wet hydraulic multi-plate clutch, 7a...clutch drum, 7b...
...Clutch hub, 7C...Clutch plate, 7d
... Retainer plate, 7e... Clutch disc, 7f... Piston, 7g... Hydraulic chamber, 8... Rear wheel differential, 9... Output gear, 10... Final gear , 11...Transfer gear, 11a...Brim portion, 12...Bevel gear, 13...Final gear, 14...Oil pump, 15...Regulator valve, 16a. 16b...Transfer clutch valve, 17a,
17b...Duty solenoid valve, 18...
Pilot valve, 19... Control unit, 21...
・Transfer shaft, 22...Differential case, 23...Support plate, 23a...Window, 24...Case member, 25.26...Knock bottle, 27...Release bearing, 27a... Outer lace, 27b
...Inner race, 27c...Retainer part, 28.
...Second wet hydraulic multi-plate clutch, 28a...Clutch drum, 28b...Clutch hub, 28c...Clutch play 1., 28d...Retainer plate, 2
8e...clutch disc, 28f...piston,
289... Hydraulic chamber, 29... Release bearing,
29a... Inner lace, 29b... Outer lace.

Claims (1)

[Claims] In a four-wheel drive vehicle configured to transmit power so that power can be distributed 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 described above is a transverse transaxle with a transfer. between the final gear and the differential case, and between the two parts in the middle of the transfer transmission shaft.
The hydraulic piston in these wet hydraulic multi-disc clutches is fixed to the case member of the transaxle as a cylinder so as to be slidably fitted therein, and the hydraulic piston is placed in a cylinder on the opposite side of the hydraulic chamber for its operation. A four-wheel drive vehicle, the working end of which is pressed against a retainer plate fitted into the end of a clutch drum of the wet hydraulic multi-disc clutch via a bearing to press a clutch plate in the clutch drum. Power distribution device.