JPH01216130A - Driving power transmitting device - Google Patents

Abstract

PURPOSE:To simplify constitution by connecting one of a pair of cam engagement bodies with a rotary shaft and fitting the other with the rotary shaft, permitting a relative revolution, and by forming the cam engagement body into a cam shape consisting of an inclined surface inclined in the revolution direction and an engagement surface perpendicular to the revolution direction. CONSTITUTION:For the positive input torque in which a torque is transmitted from a front wheel side drive shaft 15, the relative revolution speed between the drive shaft 15 and a rear wheel side drive shaft 16 increases, and the frictional engagement of a multidisc clutch 25 increases, and the transmission torque becomes over a bias set by a belleville spring 35. Then, a pair of cam engagement bodies 31 and 33 relatively revolve, and are relatively shifted in the axial direction by the cam action due to an inclined surface 34A. Therefore, an outer plate 37 and inner plate 38 are set into nearly directly connected state. On the contrary, for the reverse input torque in which a torque is transmitted from the drive shaft 16, the relative revolution between a pair of cam engagement bodies 31 and 33 is suppressed by an engagement surface 34B, and the transmission torque by the multidisc clutch 25 becomes relatively low because of an oil pressure generating means 23 only.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a driving force transmission device used in a four-wheel drive vehicle.

<Prior art> A driving force transmission system that includes a multi-disc clutch that is disposed between a front-wheel drive shaft and a rear-wheel drive shaft and transmits torque between the two shafts, and an operating piston that operates the multi-disc clutch. The device includes a hydraulic pressure generating means that generates hydraulic pressure according to the relative rotation between the front wheel drive shaft and the rear wheel drive shaft, and applies this hydraulic pressure to the actuating piston to frictionally engage the multi-disc clutch. It has become.

By the way, when a brake operation is performed while an automobile is running, the braking force becomes maximum when the wheel slip rate is in the range of 10 to 20%. For this reason, ABS (Anti-rock Break 5y) controls the brake oil pressure during brake operation to suppress the wheel slip rate within the above range, prevent the wheels from locking, and maintain the maximum braking force.
In a four-wheel drive vehicle equipped with a brake system (Sten+), it is necessary to suppress the torque transmitted between the front and rear wheels to a low level so as not to interfere with ABS control during brake operation.

<Problem to be solved by the invention> In order to meet such demands, conventionally, for example, Japanese Patent Laid-Open No.
As described in No. 50234 or Japanese Unexamined Patent Publication No. 62-43325, there is a known system that detects the operation of ABS and releases the direct connection between the front and rear wheels when the operation of ABS is detected. .

However, in the above-mentioned products, ABS
In order to detect the operation of the sensor, various sensors and controllers must be provided, which results in a complicated configuration and high cost, and there is a problem in that it is necessary to take measures against failures of the sensors and the like.

<Means for Solving the Problems> The present invention focuses on the fact that during braking, the torque has a reverse input torque characteristic where the torque flows from the rear wheel side, whereas during normal driving, the torque has a normal human power torque characteristic where the torque flows from the front wheel side. ,
This idea is used to solve the above-mentioned conventional problem, and its configuration is such that a housing is connected to one of the front wheel drive shaft and the rear wheel drive shaft, and the other is rotatably supported by the housing. A pair of cam engaging bodies are arranged in which the rotating shafts are connected to each other, and a pair of cam engaging bodies are disposed in the housing so as to be relatively rotatably engaged in a circumferential direction and press the multi-disc clutch by the relative rotation, and one of the pair of cam engaging bodies is arranged. connected to the rotating shaft;
the other is fitted to the rotating shaft so as to be relatively rotatable, and the cam engaging body has a cam shape consisting of an inclined surface inclined in the rotational direction of the cam engaging body and a locking surface perpendicular to the rotational direction of the cam engaging body. It was configured as follows. It is something. With the above configuration, the relative rotational speed difference between the front wheel drive shaft and the rear wheel drive shaft increases in response to positive input torque transmitted from the front wheel drive shaft, and the multi-disc clutch When the frictional engagement force increases and the transmitted torque exceeds the bias set by the disc spring, the pair of clutch engaging bodies rotate relative to each other and are displaced relative to each other in the axial direction due to the cam action of the inclined surface.

The outer plate and the inner plate are pressed by the relative axial displacement of the pair of clutch engaging bodies, and the outer plate and the inner plate are almost directly connected. As a result, the torque transmitted by the multi-disc clutch increases rapidly, making it easier to escape from mud etc., and suppressing the sliding friction between the outer plate and the inner plate to prevent damage to both plates.

Conversely, in response to reverse input torque, which is transmitted from the rear wheel drive shaft, the locking surface prevents the relative rotation of the pair of clutch engaging bodies. There is no pressing action between the outer plate and the inner plate, and as a result, the torque transmitted by the multi-disc clutch is relatively low due to only the hydraulic pressure generating means, and matching with the ABS is achieved.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 4, 10 is an engine, 11 is a transmission, 13 is a front wheel differential device, 14 is a rear wheel differential device, 15 is a front wheel drive shaft, 16 is a rear wheel drive shaft, 17 is a front wheel, and 18 is a rear wheel drive shaft. Reference numeral 20 indicates a rear wheel, and 20 indicates a driving force transmission device provided between the front wheel drive shaft 15 and the rear wheel drive shaft 16. The output of the engine 10 is transmitted to the front wheel differential device 13 via the transmission 11 to drive the front wheels 17, and is also transmitted to the front wheel drive shaft 15, and its rotation is transmitted to the rear wheel side via the drive force transmission device 20. is transmitted to the drive shaft 16, and the rear wheel 1
Drive 8.

As shown in FIG. 1, the driving force transmission device 20 includes a rotary housing 21, a rotary shaft 22 that extends vertically through the rotary housing 21 and is rotatably supported, and a rotary housing 21 and a rotary shaft 22. A hydraulic pressure generating means 23 that generates hydraulic pressure according to the differential rotation of the hydraulic pressure generating means 23 and an operating piston 24 to which the hydraulic pressure generated by the hydraulic pressure generating means 23 is applied are frictionally engaged by the pressing force of the operating piston 24. It is mainly composed of a multi-disc clutch 25.

The front wheel drive shaft 1 is disposed at one end of the rotating housing 21.
5 are integrally connected to each other, and the rear wheel drive shaft 16 is spline-engaged within the rotary shaft 22. A lubricating oil chamber 27 is formed in the rotating housing 21 concentrically with the rotating shaft 22 , and one end opening of the lubricating oil chamber 27 is closed by an end cover 28 . Inside the lubricating oil chamber 27, a clutch hub 31 constituting seven sides of a pair of cam engaging bodies 30 is rotatably and axially movably supported on the outer periphery of the rotating shaft 22. Balls 32 are held at equal angular intervals on the circumference. A torque receiving body 31A is provided at one end of the clutch hub 31 so as to sandwich the multi-disc clutch 25 between it and the operating piston 24. Further, a cam plate 33 constituting the other of the pair of cam engaging bodies 30 is spline-engaged with the outer periphery of the rotating shaft 22 . On the surface of the cam plate 33 facing the end surface of the clutch hub 31, the same number of cam grooves 34 that engage with the engagement balls 32 are formed at equal angular intervals on the circumference. As shown in the figure, it consists of an inclined surface 34A that is inclined with respect to the rotation direction, and a locking surface 34B that is perpendicular to the rotation direction, and the engaging ball 32 is sandwiched between the sloped surface 34A and the locking surface 34B. It is located in As a result, the clutch hub 31
When the clutch hub 31 rotates in the direction of the arrow, the rotation is integrally transmitted to the cam plate 33 via the retaining ball 32 by the action of the locking surface 34B, and when the clutch hub 31 rotates in the opposite direction of the arrow, the rotation is transmitted integrally to the cam plate 33 via the retaining ball 32. An axial component force is applied to the cam plate 33 by the action of the surface 34A. The cam groove 34 of the cam plate 33 is normally engaged with the engagement ball 32 by the optical force of a disc spring 35 inserted between the clutch hub 31 and the clutch hub 31.

Furthermore, inside the lubricating oil chamber 27, there are a plurality of outer plates 37 and inner plates 3 that constitute the multi-plate clutch 25.
8 are arranged alternately, the outer plates 37 are spline engaged with the inner periphery of the rotating housing 21, and the inner plates 38 are spline engaged with the outer periphery of the rotating shaft 22.

A cylindrical space 40 limited in the axial direction is formed between the working piston 24 and the inner end of the rotary housing 21, and a rotor having a wall thickness slightly smaller than the axial dimension of the space 40 is formed in the space 40. 41 is housed in a slidable manner. As shown in FIG. 2, the rotor 41 has a center portion splined to the outer periphery of the rotating shaft 22, and has two blades 42 extending in the diametrical direction. As a result, the space 40 is circumferentially divided into a plurality of pressure chambers 43 by a plurality of blades 42, and each pressure chamber 43 space is filled with high viscosity oil 44 such as silicone oil. The oil pressure generating means 23 is constituted by the rotor 41 having the blades 42 housed in the cylindrical space 40 and the high viscosity oil 44. Such hydraulic pressure generating means 2
As shown in the transmission torque characteristics shown in FIG. 5, the hydraulic pressure generated by 3 generates a relatively low transmission torque with respect to the differential rotation.

In the above-mentioned configuration, under normal running conditions, the positive input torque characteristic is such that torque flows from the front wheel side to the rear wheel side, so the front wheel drive shaft 15 and the rear wheel drive shaft 16 rotate relative to each other, causing the rotor to rotate. 41 relatively rotates within the rotating housing 21, the high viscosity oil 44 filled in the pressure chamber 43 is forcibly moved by the blade 42 between the two closely spaced surfaces at a flow rate corresponding to the rotational speed difference. At this time, the rotating housing 21
An internal pressure proportional to the rotational speed of the rotor 41 is generated in the pressure chamber 43 due to viscous friction with both end surfaces of the actuating piston 24 . That is, as the blade 42 rotates in the direction of the arrow with respect to the rotary housing 21, this internal pressure is generated such that the leading blade side of the pressure chamber 43 surrounded by two adjacent blades 42 is B and the succeeding blade side is A. Then, the pressure distribution becomes highest at point A and lowest at point B, and a pressure proportional to the rotational speed of the blade 42 is generated in the pressure chamber 43, and this pressure acts on the actuating piston 24 and presses the multi-disc clutch 25. do.

Therefore, a plurality of outer plates 37 and inner plates 38
are frictionally engaged by a pressing force corresponding to the hydraulic pressure acting on the actuating piston 24, and rotational torque is transmitted from the front drive shaft 15 to the rear drive shaft 16 via the multi-disc clutch 25.

However, the transmitted torque is set relatively low.

By the way, the differential rotation (relative rotational speed difference) between the front wheel drive shaft 15 and the rear wheel drive shaft 16 increases, and as a result, the differential rotation in which the transmitted torque exceeds the bias set by the disc spring 35 occurs. When reaching Nl (Fig. 5), the clutch hub 31
, the clutch plate 33 rotates relatively against the disc spring 35, and the engagement ball 32 rotates against the inclined surface 34A of the cam plate 33.
As a result, the clutch hub 31 is displaced in the axial direction with respect to the clutch plate 33, and the torque receiving body 3
1A, the multi-disc clutch 25 is pushed toward the actuating piston 24. Due to this axial displacement of the clutch hub 31, the outer plate 37 and the inner plate 38 are almost directly connected, resulting in a four-wheel drive state. As a result, the torque transmitted by the multi-disc clutch 25 increases sharply after reaching a predetermined differential rotation N1, as shown in the torque transmission characteristics of FIG. 5, making it easier to escape from mud or the like.

However, during braking, a reverse input torque characteristic occurs in which torque flows from the rear wheel side to the front wheel side, so the cam plate 3
Since the relative rotation between the clutch hub 31 and the clutch plate 33 is restricted by the locking surface 34B of No. 3, the above-mentioned sudden increase in the transmitted torque does not occur, and the multi-disc clutch 25 is allowed to slip, which interferes with ABS. This will prevent it from affecting you.

In the above-mentioned embodiment, an example was described in which the hydraulic pressure acting on the actuating piston 24 is generated by forcibly moving high-viscosity oil with a blade, but it may also be generated using a conventionally well-known differential pump. good.

Furthermore, in the embodiment described above, the pair of cam engaging bodies 30
Although an example has been described in which the cams are engaged through the engagement ball 32, based on the same idea, the pair of cam engagement bodies 30 may be engaged with each other through their serrated cam surfaces.

<Effects of the Invention> As described above, the present invention is designed so that the transmitted torque increases in accordance with the differential rotation during a positive input, and so that the transmitted torque does not increase much with respect to the differential rotation during a reverse input. Since the cam engaging body is configured, there is no problem with ABS control even in a four-wheel drive vehicle equipped with ABS, and such transmission torque characteristics can be obtained without any special control.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of the driving force transmission device, FIG. 2 is a sectional view taken along the line n--■ in FIG. 1, and FIG. 3 is a sectional view taken along the line FIG. 4 is a schematic diagram of a four-wheel drive vehicle, and FIG. 5 is a diagram showing transmission torque characteristics with respect to differential rotation. 15... Front wheel side drive shaft, 16... Rear wheel side drive shaft, 2
1... Rotating housing, 22... Rotating shaft, 23...
- Hydraulic pressure generating means, 24... Working piston, 25...
Multi-plate clutch, 31, 33... cam engagement body.

Claims (1)

[Claims] (1) A multi-disc clutch that is disposed between the front-wheel drive shaft and the rear-wheel drive shaft and transmits torque between the two shafts, an actuating piston that presses the multi-disc clutch, and the front-wheel drive shaft. and a hydraulic pressure generating means for applying hydraulic pressure to the actuating piston in accordance with differential rotation with the rear wheel drive shaft, the housing being disposed on one of the front wheel drive shaft and the rear wheel drive shaft. a pair of cams, the other of which is connected to a rotary shaft that is rotatably supported by the housing, the cam engages within the housing so as to be relatively rotatable in the circumferential direction, and presses the multi-disc clutch by relative rotation. an engaging body is arranged, one of the pair of cam engaging bodies is connected to the rotating shaft, the other is fitted to the rotating shaft so as to be relatively rotatable, and the cam engaging body is tilted in the rotation direction of the cam engaging body. A driving force transmission device configured with a cam shape consisting of an inclined surface and a locking surface perpendicular to the rotational direction of the cam engaging body.