JPH02261948A - Differential limiting device for car - Google Patents

Abstract

PURPOSE:To enhance the control accuracy for the working oil pressure by fitting a piston of a wet type hydraulic multi-plate clutch slidably in a cylinder in clutch housing as a stationary member in such a way that rotation is stopped, and thereby eliminating centrifugal oil pressure action. CONSTITUTION:A wet type multi-plate clutch 19 is interposed between a differential case 9a of an independent differential device 4 and axles 14, 15, and a working oil pressure is supplied to a piston 19g fitted slidably in a clutch housing 17 as a stationary member in such a way that rotation is stopped, according to the running condition and road surface situation. It is put in contact with a clutch disc 19c of a clutch drum 19a through a thrust bearing 32, and the power is transmitted to the left and right drive wheels at desired proportion. Because the working oil and lubricant are supplied from a sump of the device body 4 through a hydraulic control device, a proper oil type can be used, and smooth slip action is obtainable. This enhances accuracy of the working oil pressure control, and the cornering characteristic of car at the time of swinging the head can be controlled.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention controls the hydraulic pressure applied to a wet hydraulic multi-disc clutch according to the running condition of the vehicle or the road surface condition, and through this control, applies the hydraulic pressure to the left and right drive wheels of the vehicle. The present invention relates to a differential limiting device for a vehicle that can variably control the transmission torque of the vehicle.

[Conventional technology]

As such a vehicle differential limiting device, Japanese Patent Application Laid-Open No. 62-1
Publication No. 43719 or JP-A-62-134339
The method described in the above publication is conventionally known. This is a wet-hydraulic multi-disc clutch that generates torque between the differential case and side gear of the left and right differential gear that limits the differential operation of the differential gears, and by controlling the operating hydraulic pressure. The differential limiting torque is changed to obtain good turning performance. Here, in the wet hydraulic multi-disc clutch, the lubricating oil for the multi-disc clutches such as the clutch play 1 and the clutch disc is shared with the lubricating oil for the final reduction gear (hypoid gear port) outside the differential case.

[Problem to be solved by the invention]

In this way, in the past, the lubricating oil for wet hydraulic multi-disc clutches was
The wet hydraulic multi-disc clutch has appropriate friction characteristics over a wide operating range because it is shared with the lubricating oil for final reduction gears that contains extreme pressure additives, with an emphasis on high blood pressure at the meshing contact surface of final reduction gears. However, when applying a sliding action to the clutch plate as necessary, the transmitted torque becomes unstable, resulting in stick-slip, which causes muffled noise and vibration noise from the vehicle body.

Therefore, the present invention prevents the occurrence of stick-slip when a wet hydraulic multi-disc clutch slips depending on the driving condition of the vehicle and the road surface condition, and also improves the control accuracy of the working oil pressure for the wet hydraulic multi-disc clutch. The object of the present invention is to provide a differential limiting device for a vehicle that can improve the performance.

[Means for Solving the Problems] For this purpose, the present invention provides a system that changes the transmitted torque between the differential case and the axle shaft in an independent differential device for front wheels or rear wheels according to the control of hydraulic pressure. A wet hydraulic multi-plate clutch is installed to limit the differential.
This wet type hydraulic multi-disc clutch is disposed in a clutch housing provided around the axle shaft so as to be separated from the lubricating oil for the final reduction gear in the independent differential, and is connected to the wet type hydraulic multi-disc clutch. a hydraulic control device that controls the working hydraulic pressure of the hydraulic multi-disc clutch from an oil reservoir provided in the independent differential device body via a hydraulic power source according to the running condition of the vehicle, and the piston in the wet hydraulic multi-disc clutch is a fixed member The above-mentioned clutch housing is used as a cylinder, and the clutch housing is fixed to rotate and slidably fitted therein, and is brought into contact with a clutch plate in a clutch drum via a bearing.

[For production]

In this type of means, a wet hydraulic multi-disc clutch is interposed between the differential case of the independent differential device and the axle shaft, so the hydraulic pressure is controlled according to the vehicle running condition and road surface condition. The differential limiting torque changes continuously to a desired l/lux value, and power is transmitted to the left and right drive wheels of the vehicle at an arbitrary ratio. The hydraulic oil and lubricating oil for this wet hydraulic multi-disc clutch are arranged in the clutch housing so as to be separated from the lubricating oil for the final reduction gear in the independent differential, so lubrication is focused on the hypoid gear. Instead of oil, it is possible to use suitable hydraulic oils and lubricating oils with a certain composition, which will give the desired friction properties, for example, a large steering turn on a paved road, resulting in a difference in rotation between the left and right wheels. It slides smoothly without any stick-slip even in the case of abrasion.

In addition, the piston of a wet hydraulic multi-disc clutch is configured to be fitted into the clutch housing, which is an immovable member, so that centrifugal hydraulic pressure does not act on the hydraulic chamber of the piston even if the clutch drum rotates. control becomes more accurate, and the control accuracy of the differential limiting torque generated by the wet hydraulic multi-disc clutch is improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows a schematic configuration of a transmission system of a vehicle to which an embodiment is applied, in which an engine 1 degree transmission 2 is disposed vertically in the longitudinal direction of the vehicle body, a propeller shaft 3. Power is transmitted to left and right rear wheels 5a and 5b via an independent differential gear 4 for rear wheel drive.

As shown in FIG. 1(a), the independent differential device 4 houses a hypoid pinion gear 7, which is a final reduction gear, a hypoid drive gear 8, and a rear differential 9 in a differential carrier 6. The rear end is covered with a cover IO,
Further, an extension case 11 is connected to the front end. The hypoid pinion gear 7 has a shaft portion 7a connected to the propeller shaft 3 that is connected to the double taper roller bearing 12 on the differential carrier 6 side.
and ball bearing 1 on the extension case 11 side.
3 and is rotatably supported at two points. Also, a hypoid drive gear 8 that meshes with this hypoid pinion gear 7
is fixed to the flange portion of the differential case 9a of the rear differential 9 with bolts.

The rear differential 9 has a binion shaft 9
A differential case 9a accommodates a differential binion 9C rotatably supported by a differential binion 9C, left and right side gears 9d and 9e meshing with the differential binion 9C, and the like.
Left and right axle shafts 14.15 spline-fitted to the side gears 9d, 9e are rotatably fitted and inserted into the cylindrical portions 9r, 91' of the differential case 9a. The cylindrical portions 9r, 9r of the differential case 9a are connected to the retainer bearing 16 and the clutch housing 17, which are fitted and fixed to the differential carrier B, and the tapered roller bearing 1.
8.18, and a wet hydraulic multi-disc clutch 9 is interposed between one cylindrical portion 9'' of the differential case 9a and the corresponding axle shaft 15. has been done.

Here, the clutch housing 17 covers the wet hydraulic multi-disc clutch 19 and is internally partitioned in a fluid-tight manner by an oil seal 20 externally mounted on the cylindrical portion 9r and an oil seal 21 externally mounted on the axle shaft 15. Pinion gear 7, hypoid drive gear 8. The lubricating oil from the double taper roller bearing 12° taper roller bearing 1g, rear differential 9, etc. is prevented from entering the clutch housing 17. In order to lubricate the wet hydraulic multi-disc clutch 19 inside this clutch housing 17 with a special lubricating oil and to supply this lubricating oil to the hydraulic chamber of the wet hydraulic multi-disc clutch 19, an electric motor is installed on the side of the differential carrier 6. An oil pump 22 of the type shown in FIG.

In the wet hydraulic multi-disc clutch [9], as shown in FIG. 1(e), the clutch drum 19a is connected to the axle shaft 15.
The clutch hub 19b is spline-fitted to the middle of the clutch housing 17 through a thrust bearing 81, and the clutch hub 19b is spline-fitted to the outer periphery of the cylindrical portion 9r of the differential case 9a. A plurality of ring-shaped clutch plates 19c are spline-fitted to the inner periphery of the clutch drum 19a.
On the other hand, on the outer periphery of the clutch hub 19b, a plurality of ring-shaped clutch discs 19 (' is the clutch plate 1
9c and spline fitting, these glue, latch play 1t9c, clutch disc 191
' A multi-disc clutch is constructed. The piston 19g that applies a pressing force to such a multi-disc clutch is a ring-shaped piston that is slidably fitted into the inner circumference of the clutch housing 17, which is a stationary member, and the outer circumference of an inner guide tube 17a formed in the clutch housing 17. A hydraulic chamber 19b is formed between the clutch housing 17 and the clutch housing 17.

The piston 19g is slidably fitted into a guide pin 17b installed in the clutch housing 17 and is prevented from rotating. Further, the operating end on the side opposite to the hydraulic chamber 19h is brought into contact with the clutch plate 19c in the clutch drum 19a via a thrust bearing 32, and also with the 1111 spring 19j for return.

On the other hand, the oil pump 22 is an internal gear pump in which an inner rotor 22a driven by a motor and an outer rotor 22b meshing therewith are rotatably accommodated in an oil pump carrier Ba formed in the differential carrier 6. It is configured to communicate with a hydraulic control device 23 and an oil strainer 25 in an oil pan 24 via a passage (see FIG. 3).

The hydraulic control device 28 is a regulator valve 2B.

Clutch control valve 27. Pilot valve 2
8, etc., and communicates with the hydraulic chamber 19b of the wet type hydraulic multi-disc clutch 19 from an oil passage (not shown) through an oil hole 17c provided in the clutch housing 17.

Further, the lubricating oil of the wet hydraulic multi-disc clutch 19 communicates with the inside of the clutch housing 17 via an oil passage 17d provided in the clutch housing 17.

Here, the hydraulic control system of the wet hydraulic multi-disc clutch 19 will be explained. As shown in FIG. 3, the clutch control valve 27, which is interposed in the oil path from the oil pump 22 to the hydraulic chamber 1911 of the wet hydraulic multi-disc clutch 19, is operated to control the duty pressure. A duty solenoid valve 29 for discharge control is installed in the pilot pressure hydraulic circuit that reaches the clutch control valve 27 via the pilot valve 28.
is inserted.

By adjusting the duty solenoid valve 29 to a desired duty pressure by the duty signal from the control unit h30, the clutch control valve 27
is adjusted to a desired clutch pressure. The wet hydraulic multi-disc clutch 19 changes the transmission torque (differential limiting torque) in accordance with this change in clutch pressure, and the relationships between the duty ratio and duty pressure and between the duty pressure and differential limiting torque are Figure (a), (
As shown in b). Further, the oil whose pressure is regulated by the pressure regulator valve 26 reaches the inside of the clutch housing 17 via an oil passage 17d of the clutch housing 17, where it lubricates the clutch plate 19C, clutch disc 19r, etc.

FIG. 5 shows the flow of processing performed within the control unit 30. First, the left and right drive wheels 5a.

5b is detected and the presence or absence of slip of the left and right wheels is calculated, and if the slip of the left and right wheels is less than or equal to the set value, a preset map based on throttle opening, vehicle speed, acceleration, gear position, steering angle, etc. Search for the required differential limit] Then, a duty ratio corresponding to the torque transmission capacity of this clutch is selected and outputted to the duty solenoid valve 29. Here, if the slip of the left and right wheels exceeds a predetermined value, it is determined that a slip has occurred, and the map value at the time of slip occurrence is retrieved and output to the duty solenoid valve 29.

In the vehicle having the above configuration, the power transmitted from the engine 1 through the transmission 2 is appropriately changed in speed and inputted to the independent differential gear 4 through the propeller shaft 3. The power is then transmitted to the left and right rear wheels 5a, 5b via the differential gear 1 noncial 9 in the independent differential device 4.
Wheel drive.

Here, a wet hydraulic multi-disc clutch 19 with variable transmission torque is interposed between the cylindrical portion 9r of the differential case 9a of the rear differential 9 and the axle shaft 15. The limit torque changes continuously. That is, the differential limiting torque changes continuously as the clutch pressure changes according to the duty ratio signal from the control unit 30. For example, when the duty pressure is 100% and the transmission torque of the wet hydraulic multi-disc clutch 19 is zero, no differential limiting action is performed.
When the left and right rear wheels 5a, 5b are traveling straight and the road surface resistance is equal, the resistance applied to the left and right side gears 9d, 9e is equal, so the binion does not rotate, and the differential case 9a, binion shaft 9b, and side gear 9
d and 9e rotate as a unit, and the drive torque of the left and right wheels is divided into 50% and 50% power, and when the left and right drive wheels are turning with equal road resistance, they are freely used for differential operation.

However, when one wheel comes into contact with a road surface with a high coefficient of friction such as a paved road,
When the opposite side is in contact with a road surface with a low coefficient of friction such as compacted snow or muddy ground, when the differential case 9a rotates, differential operation occurs due to the difference in road resistance from the left and right wheels, and the one side that is in contact with the road surface with a high coefficient of friction The drive wheels do not lose their driving force, making it difficult to escape from muddy, uneven, or snowy terrain, for example.

On the other hand, when the duty ratio is 0%, the wet hydraulic multi-disc clutch 1
9 is directly connected, the differential 9 will be locked, and the left and right rear wheels 5a + 5b have different road friction coefficients, and even if there is a difference in road resistance, the power will be divided into 50% and 50%. The driving force is ensured.

In particular, when the duty ratio is increased from 0%, the transmission torque of the wet hydraulic multi-disc clutch 19 gradually decreases and the differential lock state is gradually released.If the differential limiting torque is set to a low value, the left and right When turning with equal road resistance, the rear wheels 5a and 5b operate differentially due to the difference in rotation between the left and right wheels. Also, when turning with different road friction coefficients, the drive wheel with the higher road friction coefficient applies less driving force. It performs its working action without loss. In the differential mode and in the straight-ahead state, power is applied to the left and right rear wheels 5a, 5b while freely changing the differential limiting torque within a range up to a predetermined ratio by differential limiting action according to the vehicle running condition and road surface condition. It is distributed.

Therefore, a throttle opening signal is sent to the control unit 30.

Input various signals such as shift range signals, left and right rear wheel rotation signals, steering angle signals, etc., search for the optimal duty ratio from a table map of duty ratios set in advance for each shift range, and output the signal. Accordingly, when the vehicle is at high speed or when accelerating at low speed.

It is possible to optimally distribute power to the left and right rear wheels 5a and 5b according to various driving conditions and road conditions such as when decelerating, going straight, and turning, improving running stability, drivability, starting performance, etc. I can do it. Furthermore, in a vehicle equipped with an anti-lock brake system, the differential state between the left and right rear wheels 5a, 5b during operation is obtained by releasing the wet hydraulic multi-disc clutch 19, so the anti-lock brake can effectively demonstrate its functions.

Now, looking at the behavior of the wet hydraulic multi-disc clutch 19 when differential limiting is activated, such as when the vehicle is turning with equal road resistance, the duty solenoid is Since the valve 29 is duty-controlled, the hydraulic pressure regulated to a predetermined value by the clutch control valve 27 acts on the hydraulic chamber 19h, and the clutch plate 19c and clutch disc 1
91', relative slippage occurs. In this case, the wet hydraulic multi-disc clutch 19 is disposed within the clutch housing 17 so as to be separated from the lubricating oil (hypoid gear oil) for the hypoid pinion gear 7, hypoid drive gear 8, etc., and is provided with an appropriate lubricating oil having a predetermined composition. Because it is used, the desired friction characteristics are obtained, and the vehicle slides smoothly without stick-slip. Therefore, the vehicle does not generate unpleasant vibrations or noise, and the friction materials such as the clutch plate 19c The desired reliability and durability can also be obtained.

Furthermore, the piston 19g of the wet hydraulic multi-disc clutch 19 is not housed in the clutch drum 19a, which is a rotating member, but is fitted into the clutch housing 17, which is an immovable member, so that the piston 19g is prevented from rotating. Even if the hub 19b rotates, the piston 19g does not rotate, and no centrifugal oil pressure is generated in the hydraulic chamber 19h. Therefore, the control of the working oil pressure becomes accurate, and the control accuracy of the wet hydraulic multi-plate clutch 19 is improved, and the driving and braking stability in the medium to high speed range is improved.

The above-mentioned embodiment shows the application of the present invention to a two-wheel drive vehicle with a front engine/rear drive (FR) system.
It goes without saying that the present invention is also applicable to wheel drive vehicles or work vehicles capable of driving multiple wheels. Also, although we have shown a configuration in which an oil pump and hydraulic control device are attached to an independent differential, it is also possible to use a vehicle other than an independent differential! ,
It goes without saying that the present invention can also be applied to a device that is attached to an engine or transmission and configured with external piping.

〔Effect of the invention〕

As explained above, according to the present invention, a wet hydraulic multi-plate clutch is interposed between the differential case of the independent differential device and the axle shaft to generate a torque that limits the differential operation of the differential gears. The differential limiting torque changes continuously according to the control of the hydraulic pressure, and power is transmitted to the left and right drive wheels at an arbitrary ratio depending on the vehicle's driving condition and road surface condition. In addition to making it easier to escape and run, it is possible to obtain optimal driving and braking stability for the vehicle depending on the road surface conditions, and to control the cornering characteristics of the vehicle when turning. This wet hydraulic multi-disc clutch is disposed within the clutch housing so as to be separated from the lubricating oil for the final reduction gear in the independent differential, so it is supplied with an appropriate hydraulic oil and lubricating oil having a predetermined composition. By doing so, a wet hydraulic multi-disc clutch can obtain the desired friction characteristics, and when driving on a paved road with equal road resistance, with large steering changes and applying differential limiting torque to the left and right wheels. It also glides smoothly without unpleasant stick-slip.

In addition, the piston of the wet hydraulic multi-disc clutch is configured to be fitted into the clutch housing, which is the stationary part I4, so that centrifugal hydraulic pressure does not act on the piston, so the control of the working hydraulic pressure is accurate. The control accuracy of the wet hydraulic multi-disc clutch has been improved in the Samurai from medium to high speed range, and the drive,
Braking stability is improved.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view of essential parts showing one embodiment of the present invention, FIG. 1([)) is a sectional view taken along the line B-B of FIG. 1(a), and FIG. FIG. 2 is a schematic diagram of the transmission system of a vehicle to which one embodiment is applied, FIG. 3 is a hydraulic control circuit diagram used in one embodiment, and FIG. 4 (a) is an enlarged sectional view of the FIG. 4(b) is a characteristic diagram of duty-I pressure, FIG. 4(b) is a characteristic diagram of differential limit i-Luke, and FIG. 5 is a flowchart of arithmetic processing in the control device. 1...Engine, 2 ...transmission, 3.
...Propeller shaft, 4...Independent differential gear, 5a,
5b... Rear wheel, 6... Differential carrier, 7... Hypoid pinion gear, 7a... Mid-south part, 8... Hypoid drive gear, 9... Rear differential, 9a... Differential case, 91]...Pinion shaft, 9C...Differential binion, 9d9e...Zydogya, 9
r...Cylinder part, 10...Cover 11...Extension case, 12...Double taper roller bearing, 13...Ball bearing, 14. t5
... Axle shaft, 1B... Retainer bearing, 17... Clutch housing, 17a... Inner guide tube, 17b... Guide bin, 17c... Oil hole, 17d... Oil path, 18 ...Taber roller bearing, 19...Wet type hydraulic multi-plate clutch, 19a...Clutch drum, 19b...Clutch hub, 19c...
・Clutch play), 19f...clutch disc,
19g... Piston, l 9 h... Surface pressure chamber, 19
j...Disc spring, 20.21...Oil seal, 22
...Oil pump, 23...Hydraulic control device, 24.
・・Oil pan, 25・・Oil strainer, 2B・
...Regulator valve, 27...Clutch control valve, 28...Pilot valve, 29...
Duty solenoid valve, 30...Control unit, 81.32...Thrust bearing. Sai 41 journey

Claims (1)

[Claims] A wet hydraulic multi-disc clutch that limits the differential by varying the transmitted torque in accordance with the control of the working oil pressure, between the differential case and the axle shaft in an independent differential device for front wheels or rear wheels. This wet-type hydraulic multi-plate clutch is arranged in a clutch housing provided around the axle shaft so as to be separated from the lubricating oil for the final reduction gear in the independent differential, and The piston in the wet hydraulic multi-disc clutch is provided with a hydraulic control device that controls the working hydraulic pressure to the hydraulic multi-disc clutch from an oil reservoir provided in the independent differential device body via a hydraulic source according to the running state of the vehicle. This differential limiting device for a vehicle is constructed by using the above-mentioned clutch housing, which is an immovable member, as a cylinder, which is fixedly rotated and slidably fitted into the cylinder, and is brought into contact with a clutch plate in a clutch drum via a bearing.