JPH0241936A - Power distribution device for four wheel driving vehicle - Google Patents

Abstract

PURPOSE:To make it possible to set torque distribution to front and rear wheels in any ratio, and to meet driver's choice in driving by providing a group of switches possible to choose respective running mode of FF running, FR running and 4WD running. CONSTITUTION:Four wheel drive is performed through that power transmitted to a manual transmission 3 from an engine 1 via a clutch 2 is properly converted thereat, and one is input to a differential gear for front wheels 7 from a transmission output shaft 9 via a transfer device 4, a propeller shaft 5, and a first hydraulic wet multiple disc clutch 22, and the other is input to a differential gear for rear wheels 8 via a propeller shaft 6 and a second hydraulic wet multiple disc clutch 28. On this occasion, power is distributed to front wheels and rear wheels in accordance to transmitting torques on respective hydraulic wet multiple disc clutches 22, 28. The distribution ratio depends on change in clutch pressure according to duty ratio from a control unit, thereby a vehicle becomes if FF, 4WD and FR state.

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 suppressing the clutch plates 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. Internal w1 occurs due to a difference in the effective diameter of the tires between the front and rear wheels due to differences in the axle load distribution of the vehicle during driving or movement of the center of gravity during acceleration.
The wet hydraulic multi-disc clutch cannot sufficiently absorb ring torque as a torque limiter, resulting in disadvantages such as reduced acceleration performance, poor fuel efficiency, and generation of vibration noise. In addition, wet hydraulic multi-disc clutches share the same lubricating oil specifically for gears as their working oil, which makes it impossible to obtain appropriate frictional characteristics when a slipping effect occurs due to large steering changes when driving in four-wheel drive. Therefore, there is a problem that stick-slip occurs and vibration noise is generated. Furthermore, since the transfer device accommodates two wet-type hydraulic multi-disc clutches and becomes elongated, its rigidity decreases, increasing vibration and noise in the drive system, or reducing the space inside the vehicle. 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 device configuration on the transfer side. It prevents the occurrence of stick-slip and improves the vehicle's handling and starting performance. The purpose is to maximize turning performance and to fully respond to the driver's driving preferences.

[Means to solve the problem]

For this purpose, the present invention provides a four-wheel drive vehicle that is configured to transmit power between the front and rear wheels in accordance with the pressure control of hydraulic fluid to two wet hydraulic multi-disc clutches, in which a propeller shaft is connected to each of the front and rear wheels from a transfer device. Equipped with an independent differential device for the front wheels and an independent differential device for the rear wheels,
The above-mentioned two wet-type hydraulic multi-disc clutches are separately arranged in the above-mentioned independent differential device for front wheels and independent differential device for rear wheels, and are interposed in the middle of the transmission shaft, and the hydraulic pistons in these wet-type hydraulic multi-disc clutches The case members of each of the independent differentials, which are immovable members, are fixed as cylinders and are slidably fitted to each other, and the working end opposite to the hydraulic chamber for operation is connected to the wet hydraulic pressure chamber. The retainer plate fitted into the end of the clutch drum of the multi-disc clutch is press-contacted via a bearing to press the clutch plate in the clutch drum, and the control system of the double-temperature hydraulic multi-disc clutch is a FF drive that transmits power only to the front wheels via one wet hydraulic multi-disc clutch,
A set of switches that allows you to select between 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 thermal hydraulic multi-disc clutches. will be established.

[For production]

With such means, even if the clutch plate in the clutch drum rotates due to rotation of the transmission shaft, the hydraulic pistons in each wet hydraulic multi-disc clutch do not rotate, and the gap between these and the case member of the independent differential gear does not rotate. Centrifugal hydraulic pressure is not generated in each hydraulic chamber formed in the hydraulic system, and power is distributed to the front and rear wheels at a desired ratio by hydraulic control of each wet hydraulic multi-plate clutch. Each wet hydraulic multi-disc clutch can obtain the desired friction characteristics by using an appropriate hydraulic fluid with a predetermined composition, and can be used to generate internal circulation torque between the front and rear wheels or during four-wheel drive. When the vehicle is turned significantly, the clutch plate smoothly slides without stick-slip. By controlling each wet hydraulic multi-plate clutch in accordance with the operation of the switch group, the driver can select FF, FR, 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 the power transmission system of a four-wheel drive vehicle to which one embodiment is applied, and shows the engine 1. Clutch 2. Synchronous mesh manual transmission tl13. The transfer device 4 is integrally arranged vertically in the longitudinal direction, and the front wheel differential device 7. A rear wheel differential device 8 is arranged respectively. As shown in FIG. 1(a), the transfer device 4 includes a transfer drive sprocket 11 and a transfer driven sprocket 12 on a transmission output shaft 9 and a front drive shaft 10 arranged parallel to the transmission output shaft 9, respectively.
The transmission output shaft 9 and the front drive shaft 10 each have companion flanges 20 and 21.
A propeller shaft 6.5 is connected to the propeller shaft 6.5 through the like. Further, as shown in FIG. 2, first and second wet hydraulic multi-disc clutches 22 and 28 are interposed between the transmission shafts in the front wheel differential device 7 and the rear wheel differential device 8. . Then, the engine 1 is connected to the manual transmission 3 via the clutch 2.
The power input to the transmission drive sprocket 11 is then shifted from the transmission output shaft 9 to the transfer drive sprocket 11. Chain 13. Transfer driven sprocket 12. Front drive shaft 10. Propeller shaft 5. The power is input to the front wheel differential device 7 via the first wet hydraulic multi-plate clutch 22, and is transmitted from there to the left and right front wheels 23. Further, the power taken out from the transmission output shaft 9 to the rear of the transfer device 4 is transmitted to the propeller shaft 6,
The power is input to the rear wheel differential device 8 via the second wet hydraulic multi-disc clutch 28, and is transmitted from there to the left and right rear wheels 24. Here, the above-mentioned 1. Second two wet hydraulic multi-disc clutches 2
2.28 is an oil pump 14a that is 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, and pilot valves 18a, 18b. A dedicated hydraulic control system supplies appropriate control hydraulic pressure depending on the driving condition. It looks like this. Since these hydraulic control systems have substantially the same configuration, one of them will be explained.The pressure is adjusted 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 22. A transfer clutch valve 16a is interposed therebetween, and a duty solenoid valve 17a for exhaust control is inserted into a pilot pressure circuit system having a pilot valve 18a. And duty solenoid valves 17a and 17b in both hydraulic control systems.
The transfer clutch valves 16a and 16b are individually adjusted to desired clutch pressures by adjusting each of the transfer clutch valves 16a and 16b to a desired duty pressure using a duty signal from the control unit 19. The relationship between the duty ratio, duty pressure, and clutch pressure is shown in FIG. 4. The first system is equipped with such a hydraulic control system. Second wet hydraulic multi-disc clutch 22. -28 is a front wheel differential device 7.-28 along with its hydraulic control system. and is compactly assembled in a differential carrier portion which is a case member of the rear wheel differential device 8. Here, the humidity-measuring hydraulic multi-disc clutch 22.28
Since the differential devices 7 and 8 have substantially the same configuration, only one of them will be described. As shown in FIG. 1(b), the differential carrier 29 has a rear wheel differential 'f1
A cylinder portion that protrudes forward so as to cover the loosely fitting portion between the shaft portion 30a of the drive pinion 30 that meshes with the final gear 25 of the propeller shaft 6IjIl and the input shaft 31 of the propeller shaft 6IjIl, and connects to the extension case 32 around the input shaft 31. 33 is integrally formed as a fixed member, as shown in FIG.
As shown in C), each of the valves 15b is provided on the lower surface of this cylinder portion 33. 16b, 17b, and 18b, and an electric oil pump 14b on the side.
are fixed respectively, and a second
A wet hydraulic multi-disc clutch 28 is arranged. 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 plate 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 cylinder 33b. The end portion of the release bearing 35 contacts the retainer plate 28d via an angular contact release bearing 35.The release bearing 35 has an outer race 35a that contacts the piston 28' and rotates toward the inner guide 33b via a pawl 35b in the rotational direction. The inner race 35c is spline-fitted to the inner periphery of the clutch drum 28a, and the rotation of the outer race 35a is restricted so that the piston 28f is prevented from rotating relative to the cylinder portion 33. On the other hand, the input Shaft 31 and shaft portion 3 of 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 on 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 i 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 inner peripheral part of the partition wall 33a of the cylinder part 33 and the extension case 3
Oil seals 36 and 37 are installed on the inner periphery of each of the two front parts. Further, the hypoid gear lubricating oil and the hydraulic oil in the differential are configured to be liquid-tight with each other by an oil seal 36 on the inner circumferential portion of the slant partition wall 33a, which have different characteristics. The control unit 19 generates a throttle opening signal. The driving 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, and the optimal one is determined from a preset table map using throttle opening and vehicle speed as parameters. The duty ratio signal is transmitted to each of the duty solenoid valves 17a,
17b, the first and second wet hydraulic multi-disc clutches 2
It is designed to control the clutch pressure of 2.28. Here, the control unit 19 receives an FF driving command signal from the FF switch 43a, an FR driving command signal from the FR switch 43b, and a 4WD driving command signal capable of distributing power between the front and rear wheels from the control 4WD switch 43c. . Then, this control unit 19 outputs a 0% duty ratio signal to only one duty solenoid valve 17a based on the FF travel command signal, and outputs a duty ratio signal of 0% to only one duty solenoid valve 17b based on the FR travel command signal. It outputs a duty ratio signal of 0% only for the vehicle, and also outputs a duty ratio signal of 0% for both duty solenoid valves 17a and 17b from a preset table map based on a 4WD driving command signal that can distribute power between the front and rear wheels.
It is designed to output a duty ratio signal in the range from 100% to 100%. The four-wheel drive vehicle having the above configuration changes the speed of the power transmitted from the engine 1 to the manual transmission 3 via the clutch 2 as appropriate, and transfers the power from the transmission output shaft 9 to the transfer device 4.
Propeller shaft 5. First wet hydraulic multi-plate clutch 22
The other signal is input to the front wheel differential device 7 via the propeller shaft 6 and the second wet hydraulic multi-disc clutch 28 to provide 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 22, 28. This distribution ratio is set to 100% for the front wheels and 0% for the rear wheels by changing the clutch pressure according to the duty ratio signal from the control unit 19.
From the FF state of %, the distribution to the rear wheels is gradually increased, and the front and rear wheels go through a direct-coupled 4WD state, and then the front wheels are 0% and the rear wheels are 10%.
It changes within a range up to a 0% 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 22, 28 functions as a torque limiter by being controlled to a desired clutch pressure, and for example, the clutch plate 28 of the clutch drum 28a lpJ
C and the clutch disk 28e of the clutch hub 28b 1111 to absorb internal circulation torque due to 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-plate clutch 22.28 detects the above-mentioned longitudinal rotation speed,
This problem is solved by reducing the clutch pressure to a desired clutch pressure according to the rotation ratio or rotation difference, thereby causing slippage in the first or second wet hydraulic multi-disc clutch 22,28. Therefore, the tight corner braking phenomenon during turning can be avoided. Furthermore, when the first or second wet hydraulic multi-disc clutch 22.28 performs such a slipping action, the multi-disc clutch, such as the clutch plate 28C and the clutch disc 28e, is immersed in an appropriate hydraulic oil having a predetermined composition. The desired traction characteristics are obtained because of the friction material, and stick-slip does not occur.Therefore, unpleasant vibrations and noises do not occur, especially during low-speed maximum steering, and the friction material also has the desired reliability and Provides durability. In such a four-wheel drive vehicle, each driving mode of FF, FR, and 4WD capable of distributing power between the front and rear wheels can be selected. For example, when the FF switch 43a is operated, a 0% duty ratio signal is output to only one duty solenoid valve 17a, and only the first wet hydraulic multi-disc clutch 22 is directly connected, and the second wet hydraulic multi-disc clutch Since 28 is released, the power is transmitted only to the front wheels and becomes FF driving mode. When the FR switch 43b is operated, a 0% duty ratio signal is output only to the other duty solenoid valve 17b, the first wet hydraulic multi-disc clutch 22 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, resulting in FR driving mode. Then, when the control 4WD switch 43c is operated, both duty solenoid valves 17a and 17b are set to 0%.
A duty ratio signal ranging from 100% to 100% is output. The pressure of the hydraulic oil applied to the second wet-type hydraulic multi-disc clutch 22, 28 is changed according to the driving condition, thereby creating a controlled 4WD driving mode in which power is constantly distributed between 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 behavior of each wet hydraulic multi-plate clutch 22, 28 itself, even if the clutch plate 28C, inner race 35c of the release bearing 35, etc. rotate together with the clutch drum 28a as the input shaft 31 rotates, the piston 28f It is prevented from rotating by the cylinder portion 33, which is an immovable member. Therefore, no centrifugal oil pressure is generated in the hydraulic chamber 28g formed between the piston 28f and the cylinder portion 33, and no unnecessary pressing force is applied to the clutch plate 28C or the like other than the pressing force due to the control oil pressure. Therefore, the hydraulic pressure control of the hydraulic chamber 281J becomes accurate, and even delicate hydraulic control becomes possible. Further, such a wet hydraulic multi-disc clutch 22, 28 is used in the front wheel differential device 7. Since the transfer device 4 is disposed within the rear wheel differential device 8, the transfer device 4 does not become long, the structure of the device becomes compact, rigidity is maintained, and vibration and noise of the drive system are not increased. 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. Also, the oil pump is the first. Although two oil pumps are provided corresponding to the second wet hydraulic multi-plate clutch, one oil pump may be shared by configuring a hydraulic circuit with external piping or the like. 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 transmission shaft, the hydraulic pistons in each wet hydraulic multi-disc clutch do not rotate, and the gap between these and the case member of the independent differential gear does not rotate. Centrifugal hydraulic pressure is not generated in each hydraulic chamber formed in the hydraulic system, so each wet hydraulic multi-plate 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, when internal circulating torque is generated due to the rotational difference between the front and rear wheels, each wet-type hydraulic multi-disc clutch uses an appropriate hydraulic fluid with a predetermined composition, so that the wet-hydraulic multi-disc clutch can achieve the desired It fully absorbs this friction by exerting its friction characteristics and smoothly sliding without stick-slip, thereby avoiding tight corner braking when turning, and improving acceleration performance and fuel efficiency when driving straight. In addition to improving this, it is also possible to prevent the generation of vibration noise. In addition, the transfer system does not have a wet hydraulic multi-plate clutch, making the configuration more compact, which maintains the bending rigidity of the drive system and avoids increases in vibration and noise, while also eliminating the need for space in the vehicle interior. be able to. Then, by operating the switch group, FF and FR. 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. .

[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 C--C of FIG. 1(b), and FIG. The figure is a schematic configuration diagram of a transmission system of a four-wheel drive vehicle to which one embodiment is applied, FIG. 3 is a hydraulic circuit diagram used in one embodiment, and FIG. 4 is a characteristic diagram of duty pressure and clutch pressure. DESCRIPTION OF SYMBOLS 1... Engine, 2... Clutch, 3... Synchronous mesh manual transmission, 4... Transfer device, 5,
6... Propeller shaft, 7... Front wheel differential, 8
... Rear wheel differential device, 9... Transmission output shaft, 10.
...Front drive shaft, 11...Transfer drive sprocket, 12...Transfer driven sprocket, 13-...Chain, 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, 20.21 ... Companion flange, 22 ... First wet hydraulic multi-plate clutch, 23.
...Front wheel, 24...Rear wheel, 25...Final gear, 26...Valve unit, 28...Second wet hydraulic multi-plate clutch, 28a...Clutch drum, 28b
...clutch hub, 28c...clutch plate,
28d... Retainer plate, 28e... Clutch disc, 28f... Piston, 28 (1... Hydraulic chamber, 29... Differential carrier, 30...
・Drive pinion, 30a...shaft part, 30b...
Oil passage, 31... Input shaft, 31a... Flange portion, 3
1b...oil path, 32...extension case,
33... Cylinder part, 33a... Partition wall, 33b.
...Inner guide tube, 34...Thrust washer, 35
...Release bearing, 35a...Outer race, 35b...Claw, 35c...Inner race, 36.
37...Oil seal, 43a...FF switch,
43b...FR switch, 43c...Control 4WD switch. Blackflies (c) 74 otsu

Claims (1)

[Scope of Claims] In a four-wheel drive vehicle configured to transmit power to the front and rear wheels in accordance with pressure control of hydraulic oil to two wet hydraulic multi-disc clutches, the transmission configuration includes transmission from a transfer device to each via a propeller shaft. The two wet hydraulic multi-disc clutches are respectively arranged in the front independent differential gear and the rear wheel independent differential gear. The hydraulic pistons in these wet-type hydraulic multi-disc clutches are interposed in the middle of the transmission shaft, and the case members of the above-mentioned independent differential devices, which are immovable members, are respectively used as cylinders, and the hydraulic pistons are fitted into these so as to be able to rotate freely. and the 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, thereby tightening the clutch plate in the clutch drum. 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.