JPH0238143A - Power distribution device of four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To enhance the safety etc. in operating a vehicle, by ingeniously determining a position at which each clutch is disposed and also making it possible to select each of FF,FR,4FR running modes by operation of a series of switches. CONSTITUTION:A first wet-type hydraulic multiple disk clutch 7 which transmits power of an engine from the side of an output gear 9 to a front wheel differential gear 4 is interposed between a final gear 10 and a diff. case 22. A second wet-type hydraulic multiple disk clutch which transmits rotations of a final gear 10 from a transfer device 5 to a rear wheel differential gear is disposed similarly inside a rear wheel differential gear. And a piston 7f which provides pressing forces to the retainer plate 7d of the clutch 7(a side 28 is equal) is only slidably fitted into a case member 24, which is an unmovable member. Its clutch controlling unit comprises a series of switches capable of selecting respective running modes of FF,FR,4WD running.

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 a power distribution device for such four-wheel drive vehicles,
The one described in Japanese Patent No. 1-155027 is conventionally known. This is a system in which two wet hydraulic multi-disc clutches, one for front wheel drive and one for rear wheel drive, are placed inside the case of a transfer device that branches and transmits power from the transmission output shaft to the front and rear wheels. It is possible to continuously distribute power to the front and rear wheels at any ratio depending on the situation. In these wet hydraulic multi-disc clutches, the hydraulic oil is shared with the lubricating oil for the gears and bearings in the transfer device, and the hydraulic piston for pressing the clutch plate rotates together with the clutch drum. ing.

[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, with a wet hydraulic multi-disc clutch, the transmitted torque becomes excessively large compared to the set value corresponding to the control hydraulic pressure, making it impossible to control the desired hydraulic pressure. As a torque limiter, the wet hydraulic multi-disc clutch sufficiently absorbs the internal circulating torque generated due to the difference in the effective diameter of the front and rear tires caused by the difference in the axle load distribution of the vehicle during driving or the movement of the center of gravity during acceleration. However, there are disadvantages such as reduced acceleration performance, poor fuel efficiency, and generation of vibration and noise. In addition, since the wet hydraulic multi-disc clutch uses a lubricating oil exclusively for gears as its working oil, it is possible to obtain appropriate friction characteristics when a slipping effect occurs due to large steering changes in four-wheel drive driving conditions. There is a problem that stick-slip occurs and vibration noise is generated. SUMMARY OF THE INVENTION In order to eliminate the above-mentioned disadvantages, the present invention prevents the generation of centrifugal hydraulic pressure in the hydraulic chamber of a wet hydraulic multi-disc clutch and the stick-slip caused by slipping, and improves vehicle maneuverability. The purpose is to maximize starting performance and turning performance, and to fully meet the driver's driving preferences.

[Means to solve the problem]

For this purpose, the present invention provides a four-wheel drive vehicle configured to transmit power between front and rear wheels in accordance with pressure control of hydraulic fluid to two wet-type hydraulic multi-disc clutches, in which one of the wet-type hydraulic multi-disc clutches is It is interposed between the final gear and the differential case in the transverse transaxle with transfer, and the other wet hydraulic multi-disc clutch is sectioned and placed in the independent differential after the transfer, and interposed in the middle of the transmission shaft. The hydraulic piston in these wet-type hydraulic multi-disc clutches is fixed to the transaxle or the case member of the independent differential device, which are immovable members, as cylinders, and is slidably fitted therein. The working end on the opposite side of the wet hydraulic multi-plate clutch 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 to press the clutch blade in the clutch drum. In addition, the control system of the above-mentioned double-temperature hydraulic multi-disc clutch includes FF driving, which transmits power only to the front wheels via one wet-type hydraulic multi-disc clutch, and power transmission only to the rear wheels via the other wet-hydraulic multi-disc clutch. A switch group is provided that allows selection of each driving mode: FR driving, which transmits power, and 4WD driving, which transmits power to the front and rear wheels via both thermal hydraulic multi-plate clutches.

[For production]

With such means, even if the clutch plate in the clutch drum rotates due to the rotation of the final gear and transmission shaft, the hydraulic piston in each wet hydraulic multi-disc clutch does not rotate, and the connection between these and the case member of the transaxle is prevented. Centrifugal hydraulic pressure is not generated in each hydraulic chamber formed between the clutches, and one or both of the wet hydraulic multi-disc clutches can obtain the desired friction characteristics by using an appropriate hydraulic oil having a predetermined composition. When internally circulating torque is generated between the front and rear wheels, or when the vehicle is turned significantly in a four-wheel drive state, the clutch plate smoothly slides without stick-slip. By controlling each wet hydraulic multi-disc clutch in accordance with the operation of the switch group, the driver can select FF, PR, and 4WD driving modes that can distribute power between the front and rear wheels.

【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 21 and a manual transmission 3 are disposed horizontally in the left-right direction, and behind them a front wheel differential device 4. Transfer device5. propeller shaft 6, f
& Wheel differential differential device 8 is arranged. The power input from the engine 1 to the manual transmission m3 via the clutch 2 is
Thereupon, the gears are changed appropriately to shift from output gear 9 to final gear 1.
0, the power is input to the front wheel differential device 4 via the first wet hydraulic multi-plate clutch 7, and is transmitted from there to the left and right front wheels. Further, the final gear 10 has a transfer device 5.
The transfer gear 11 meshes with the transfer gear 11, and the power from the transfer device 5 is extracted rearward from the transfer shaft 21 through a pair of bevel gears 12 for changing the direction. Plate clutch 28. The power is input to the rear wheel differential device 8 via the final gear 13, and is transmitted from there to the left and right rear wheels. Here, the above-mentioned 1. Second two wet hydraulic multi-disc clutches 7
．． 28 are oil pumps 14a which are directly driven by an electric motor or an engine as shown in FIG.
14b, regulator valves 15a, 15b, transfer clutch valves 16a, 16b, duty solenoid valves 17a, 17b, pilot valve 1
An appropriate control hydraulic pressure is supplied according to the running condition by a dedicated hydraulic control system having hydraulic pressure control systems 8a and 18b. These hydraulic control systems have approximately the same configuration, so to explain one of them, the pressure is regulated to a predetermined hydraulic pressure from the oil pump 14a by the regulator valve 15a, and the duty pressure is controlled by the hydraulic circuit system that extends from the oil pump 14a to the wet hydraulic multi-disc clutch 7. In addition, a duty solenoid valve 1 for exhaust control is provided in a pilot pressure circuit system having a pilot valve 18a.
7a was inserted. By adjusting the duty solenoid valves 17a and 17b in the internal hydraulic control system to desired duty pressures using the duty signal from the control unit 19, the transfer clutch valves 16a and 16b are individually adjusted to desired clutch pressures. It has become so. The relationship between the duty ratio, duty pressure, and clutch pressure is shown in FIG. 4. The first wet hydraulic multi-disc clutch 7 equipped with such a hydraulic control system, as shown in FIG. The case 22 is interposed between the two. That is, the first wet hydraulic multi-disc clutch 7 has the differential case 22 also used as the clutch hub 7b, and one end of the clutch drum 7a covering this is fitted and fixed to the final gear 10.
The other end of a is connected to the case member 2 via a support plate 23 with a window.
4 is rotatably supported. A plurality of ring-shaped clutch plates 7C are arranged on the inner periphery of the clutch drum 7a.
are spline-fitted together with the retainer plates 7d at both ends, while a plurality of ring-shaped clutch discs 7e are fitted around the outer periphery of the clutch hub 7b with each of the clutch plates 7C.
These clutch plates 7c, retainer plates 7d, and clutch discs 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.
A hydraulic chamber 7g communicating with the transfer clutch valve 1ea is formed between the case member 24 and the transfer clutch valve 1ea. 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 has an outer race 27a in contact with the piston 7f, and an inner race 27b that passes through the window 23a of the support plate 23 and is splined to the inner periphery of the clutch drum 7a, as shown in FIG. 1(e). It is in contact with the retainer plate 7d via the retainer portion 27c that fits therein. On the other hand, the second wet hydraulic multi-disc clutch 28 is shown in FIG.
), it is compactly assembled together with its hydraulic control system into a differential carrier portion, which is a case member of the rear wheel differential device 8. That is, the differential carrier 29 includes an extension case 32 that protrudes forward and surrounds the input shaft 31 so as to cover the loose fitting portion between the drive pinion 30 of the rear wheel differential 8 and the input shaft 31 of the propeller shaft 611II.
A cylinder portion 33 connected to the valves 15b, 16b, 17b, and 18 is integrally formed as a stationary member on the lower surface of the cylinder portion 33, as shown in FIG.
A valve unit 26 is integrally configured with a valve unit 26, and an electric oil pump 14b is fixed to the side surface thereof.
8 is placed. Here, in the second wet hydraulic multi-disc clutch 28, a clutch drum 28a is welded and fixed to a flange portion 31a at the rear end of the input shaft 31, and a clutch hub 28b is spline-fitted to a shaft portion 30a of the drive pinion 30. and is locked to the end of the input shaft 31 via a thrust washer 34. 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. These clutch plates 28C, retainer plates 28d, and clutch discs 28e constitute a multi-plate clutch, which is alternately arranged and spline-fitted with the clutch plates 28c. A ring-shaped piston 28f that applies a pressing force to the retainer grate 28d is connected to the cylinder portion 33, which is a stationary member.
A hydraulic chamber 28g that communicates with the transfer clutch valve 16b is formed between the partition wall 33a and the inner guide member 33b, and an operating end opposite to the hydraulic chamber 28g. contacts the retainer plate 28d via an angular contact release bearing 35. In the release bearing 35, the outer race 35a that contacts the piston 28f engages with the inner guide fl 33b in the rotational direction via the claw 35b, and the inner race 35a contacts the piston 28f.
5c is spline-fitted to the inner periphery of the clutch drum 28a, and the piston 28f is prevented from rotating relative to the cylinder portion 33 by restricting rotation of the outer race 35a. On the other hand, the input shaft 31 and the shaft portion 3 of the drive pinion 30
Oil passages 31b and 30 are provided at 0a to communicate the outer circumferential side of the clutch drum 28a and the inner circumferential side of the clutch hub 28b.
b is formed. Then, the hydraulic oil in the cylinder portion 33 is scraped up by the outer periphery of the clutch drum 28a and supplied to the oil passage 30b by an oil guide (not shown), and this hydraulic oil is guided to the inner peripheral side of the clutch hub 28b via the oil passage 30b. The multi-disc clutches, such as the clutch plate 28C and the clutch disc 28e, are lubricated through oil passages (not shown) provided in the spline portion in the radial direction. In addition, in order to prevent leakage of this hydraulic oil, the cylinder part 3
3 inner peripheral part of partition wall 33a and extension case 32
Oil seals 36 and 37 are installed on the inner periphery of the front part, respectively.Since the lubricating oil for the hypoid gear in the alt differential gear and the hydraulic oil have different characteristics, the oil seals 36 and 37 on the inner periphery of the partition wall 33a are used. They are constructed to be liquid-tight with each other. The control unit 19 generates a throttle opening signal. The running condition of the vehicle is constantly judged by inputting various signals such as rear wheel rotation signal, front wheel rotation signal, range signal, and idle signal. The duty ratio signal of each of the duty solenoid valves 17a,
17b, the first and second wet hydraulic multi-disc clutches 7
．． 28 clutch pressures are controlled. Here, the control unit 19 receives an FF driving command signal from the FF switch 40a, a PR driving command signal from the PR switch 40b, and a 4WD driving command signal capable of distributing power between the front and rear wheels from the control a14WD switch 40c. . Then, this control unit 19 controls one of the duty solenoid valves 17a based on the FF travel command signal.
Based on the PR travel command signal, a 0% duty ratio signal is output only to the other duty solenoid valve 17b, and the power is distributed between the front and rear wheels. Both duty solenoid valves 17a, 17b are activated based on possible 4WD driving command signals.
0 respectively from the table map set in advance.
It outputs a duty ratio signal ranging from % to 100%. 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, gradually increasing the distribution to the rear wheels, and creating a direct-coupled 4WD for both the front and rear wheels. After the condition, front wheel 0%, rear wheel 1
It changes within a range up to 00% FR state. 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 first or second wet hydraulic multi-plate clutch 7.28 functions as a torque limiter by being controlled to a desired clutch pressure, and the clutch drum 7a or 28a (clutch play in pl) acts as a torque limiter.
7C or 28C and clutch hub 7b or 28b
It causes slippage between the clutch disc 7e or 28e of the ill, and absorbs the internal circulation 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. In addition, when a four-wheel drive vehicle is turned 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, and this is particularly large at low speed maximum steering, requiring more driving force than necessary. This causes inconveniences such as the engine stalling when the vehicle is parked in a garage. In such a case, the first or second wet hydraulic multi-disc clutch 7.28 detects the above-mentioned longitudinal rotation speed and is controlled to reduce the clutch pressure to a desired clutch pressure according to the rotation ratio or rotation difference. , 1st
Alternatively, this problem can be solved by causing slippage in the second wet hydraulic multi-disc clutch 7.28. Therefore, the tight corner braking phenomenon during turning can be avoided. Furthermore, when the first or second wet hydraulic multi-disc clutch 7.28 performs such a slipping action, the clutch plates such as the clutch plate IC or 28C and the clutch disc 7C or 28e are kept in an appropriate hydraulic oil having a predetermined composition. The desired traction properties are obtained because the traction material is soaked in water, and stick-slip does not occur.Therefore, there is no unpleasant vibration or noise, especially during low-speed maximum steering. Provides reliability and durability. In such a four-wheel drive vehicle, each driving mode of FF, PR, and 4WD that can distribute power between the front and rear wheels can be selected. For example, when the FF switch 40a is operated, only one duty solenoid valve 17a is activated. Since a 0% duty ratio signal is output and only the first wet hydraulic multi-disc clutch 7 is directly connected, and the second wet hydraulic multi-disc clutch 28 is released, power is transmitted only to the front wheels and the FF driving mode is established. becomes. When the PR switch 40b is operated, a 0% duty ratio signal is output only to the other duty solenoid valve 17b, the first wet hydraulic multi-disc clutch 7 is released, and only the second wet hydraulic multi-disc clutch 28 is released. Since it is directly connected, power is transmitted only to the rear wheels and becomes PR driving mode. Then, when the control 4WD switch 40c is operated, duty ratio signals ranging from 0% to 100% are output to both duty solenoid valves 17a and 17b, respectively.
．． The pressure of the hydraulic oil applied to the second wet hydraulic multi-disc clutch 7.28 is changed according to the driving condition, resulting in a controlled 4WD driving mode in which power is constantly distributed to the front and rear wheels. Therefore, by appropriately selecting each driving mode, the vehicle's handling, starting performance, and turning performance can be maximized, and the driving preference of the driver can be fully met. Now, looking at the operation of each wet hydraulic multi-plate clutch 7.28 itself, the final gear 10. Even if the clutch plates 7c, 28c, the inner race 27b of the release bearing 27.35, etc. rotate together with the clutch drums 7a, 28a as the input shaft 31 rotates, the piston 7f will not move. 281 is a case member 24. which is an immovable member. Cylinder part 3
3 and does not rotate, so the piston 7f
, 28f and case member 24. Centrifugal oil pressure is not generated in the hydraulic chambers 7g, 28Q formed between the cylinder portion 33, and no unnecessary pressing force is applied to the clutch grates 7C, 28C, etc. other than the pressing force due to the control oil pressure. Therefore, the hydraulic pressure control of the hydraulic chamber 71; 1,28g becomes accurate, and delicate hydraulic control is also possible. In addition, each wet hydraulic multi-plate clutch 7.28 has a hydraulic chamber 7Q,
28Q is the case member 24. Since it is formed in the cylinder part 33, unlike 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, there is no need for a seal ring, etc., so the pressure due to leakage is reduced. Because there is less risk of drop, the wet hydraulic multi-disc clutch 7.28 has a good responsiveness to increasing and decreasing the working hydraulic pressure, and because the responsiveness of the working hydraulic pressure is good, it can be used instantly when the front or rear wheels lag. By changing the power distribution ratio,
It is possible to control the behavior of the vehicle. In addition, in such a wet hydraulic multi-disc clutch 7.28, one of the clutches is disposed on the outer periphery of the differential in the transverse transaxle with transfer, and the other is disposed in the independent differential, so that the transaxle is It does not become long and the structure of the transfer device becomes compact. Therefore, the transaxle maintains its rigidity and does not increase vibration or noise. Moreover, the space inside the vehicle is not reduced. 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 transmission shaft,
The hydraulic pistons in each wet hydraulic multi-disc clutch do not rotate, and no centrifugal hydraulic pressure is generated in each hydraulic chamber formed between them and the case member of the transaxle or independent differential. Therefore, 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 oil pressure. In addition, when internal circulating torque is generated due to the difference in rotation between the front and rear wheels, one or two wet hydraulic multi-disc clutches use an appropriate hydraulic fluid with a predetermined composition. This is fully absorbed by making the clutch exhibit the desired drag and friction characteristics and smoothly sliding without stick-slip, thereby avoiding the tight corner braking phenomenon when turning, and when driving straight. Acceleration performance and fuel efficiency can be improved, and vibration noise can also be prevented. Then, by operating the switch group, FF and PR. It is now possible to select each driving mode of the control 4WD that can distribute power between the front and rear wheels, maximizing the vehicle's handling, starting performance, and turning performance, and fully responding to the driver's driving preferences. can.

[Brief explanation of the drawing]

1(a) and 1(b) are sectional views of essential parts showing one embodiment of the present invention, FIG. 1(C) is a sectional view taken along the line CC of FIG. 1(a), and FIG. Figures ((1) is a sectional view taken along the line D-D in Figure 1(b), Figure 2 is a skeleton diagram of the transmission system of a four-wheel drive vehicle to which one embodiment is applied, and Figure 3 is a diagram of one embodiment) The hydraulic circuit diagram used, Figure 4, is a characteristic diagram of duty pressure and clutch pressure. 1... Engine, 2... Clutch, 3... Manual transmission, 4... Front wheel differential device. , 5... Transfer device, 6... Propeller shaft, 7... First wet hydraulic multi-plate clutch, 7a... Clutch drum, 7b...
...Clutch hub, 7C...Clutch plate, 7d
... Retainer plate, 7e... Clutch disc, 7t... Piston, 7g... Hydraulic chamber, 8... Rear wheel differential, 9... Output gear, 10... Final gear , 11... Transfer gear, 12... Bevel gear, 13... Final gear, 14a, 14b.
...Oil pump, 15a, 15b...Regulator valve, 16a, 16b...Transfer clutch valve, 17a, 17b...Duty solenoid valve, 18a, 18b...Pilot valve, 19...
・Control unit, 21...Transfer axis, 22...
・Differential case, 23...Support plate, 23
a... Window, 24... Case member, 25... Knock bottle, 26... Valve unit, 27... Release bearing, 27a... Outer race, 27b...
Inner race, 27c... Retainer part, 28... Second wet hydraulic multi-plate clutch, 28a... Clutch drum, 28b... Clutch hub, 28C... Clutch plate, 28d... Lite -Naprate, 28e・
...Clutch disc, 28f...Piston, 28g
...Hydraulic chamber, 29...Differential carrier, 30...Drive pinion, 30a...Shaft portion, 3
0b...Oil passage, 31...Input shaft, 31a...7 run section, 31b...Oil passage, 32...Extension case, 33...Cylinder part, 33a...Dividing wall, 33b...inner guide tube, 34...slash! -Washer, 35... Release bearing, 35a...
Outer race, 35b...claw, 35c...inner race, 36.37...oil seal, 40a...F
F switch, 40b...PR switch, 40e...
Control 4WD switch. death fu = l otsu 21d C)

Claims (1)

[Claims] In a four-wheel drive vehicle configured to transmit power to front and rear wheels in accordance with pressure control of hydraulic oil to two wet-type hydraulic multi-disc clutches, one of the wet-type hydraulic multi-disc clutches is equipped with a transfer. It is interposed between the final gear and the differential case in the horizontal transaxle, and the other wet hydraulic multi-disc clutch is partitioned into an independent differential after the transfer and interposed in the middle of the transmission shaft. The hydraulic piston in these wet-type hydraulic multi-disc clutches is fixed to the case member of the above-mentioned transaxle or independent differential device, which are stationary members, as cylinders, and is slidably engaged with the cylinder. The working end on the opposite side of the wet hydraulic multi-disc clutch 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, thereby pressing the clutch plate in the clutch drum. In addition, the control system of both wet hydraulic multi-disc clutches includes an FF that transmits power only to the front wheels via one of the wet hydraulic multi-disc clutches.
Driving modes are selectable: FR driving, which transmits power only to the rear wheels via the other wet hydraulic multi-disc clutch, and 4WD driving, which transmits power to the front and rear wheels via both wet hydraulic multi-disc clutches. A power distribution device for a four-wheel drive vehicle that is equipped with a group of switches.