JP2510133Y2 - Power transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a power transmission device, and in particular, it is disposed between both inner and outer rotating members that are coaxially and relatively rotatable, and torque transmission between these both rotating members. The present invention relates to a power transmission device.

(Prior art) As a power transmission device of this type, Japanese Patent Publication No. 61-501583
There is a power transmission device including a viscous fluid coupling (a viscous coupling) disclosed in Japanese Unexamined Patent Application Publication, No. 63-287631, a viscous coupling, a friction clutch, and a cam means for connecting both of them. . The power transmission device is disposed between the driving-side rotating member and the driven-side rotating member, and connects the two members so that power can be transmitted to each other when the both members relatively rotate to drive the driven-side rotating member. It is disposed between the driving side driven member and the driven side rotating member, between both driving side rotating members or between both driven side rotating members so that the difference in rotation between these two members when they rotate relative to each other is used. They are roughly classified into those used as a limited differential mechanism. The former coupling mechanism is mainly disposed on one power transmission line in a real-time four-wheel drive vehicle, and the latter differential limiting mechanism is mainly disposed on each differential of the vehicle.

(Problems to be Solved by the Invention) In the viscous coupling, which is the former viscous fluid coupling, the viscous fluid caused by the shear force of the viscous fluid existing between the inner and outer plates during relative rotation between the inner and outer plates. The friction torque enables the transmission of torque between the two plates, but the viscous friction torque is not so large and the rise characteristic of the torque is not good. Further, if a viscous coupling is formed to generate a large viscous friction torque, the shearing force becomes extremely large and the amount of heat generation increases, and the viscosity of the viscous fluid becomes high and its viscosity is greatly reduced. For this reason, the obtained viscous friction torque fluctuates and the torque transmission characteristic between both plates becomes unstable. Especially, when the rotational difference between both plates gradually increases and then gradually decreases, hysteresis occurs in the torque transmission characteristic. Therefore, when such a viscous coupling is used as a coupling mechanism of one power transmission path in a four-wheel drive vehicle, a differential limiting mechanism of each differential, etc., the transmission torque of one power transmission path, the differential limiting torque. Becomes unstable, affecting the running performance of the vehicle.

In the latter power transmission device, torque is transmitted between the two rotating members by viscous friction torque generated by the viscous coupling, and the viscous friction torque is converted into thrust by cam means to generate friction. The clutch is engaged, and the torque is further transmitted between the two rotating members by the friction torque of the clutch. Therefore, such a power transmission device is based on the operation of the viscous coupling, and directly includes the above-mentioned problems of the viscous coupling.

The present applicant has proposed a power transmission device for solving these problems in Japanese Patent Application No. 63-114406. The power transmission device is disposed between both inner and outer rotating members that are coaxially and relatively rotatably positioned, and is operated by relative rotation of the both rotating members to generate viscous resistance force generating means, and A friction clutch that generates a frictional engagement force that connects both rotating members so that torque can be transmitted, and that increases or decreases the frictional engagement force according to the applied thrust, and the viscous resistance force generated by the viscous resistance force generation means A thrust converting means for converting the thrust to the clutch; the thrust converting means includes a pair of cam members that rotate relative to each other in accordance with the viscous resistance force generated by the viscous resistance generating means; and cam surfaces of both cam members. The power transmission device includes a cam follower that is interposed between the cam members and acts to separate the cam members from each other.

Such a power transmission device eliminates the above-mentioned viscous coupling and solves the above-mentioned problems caused by the viscous coupling. However, in the power transmission device, the shear rate increases and the viscosity of the viscous fluid decreases as the differential rotation speed increases, so the increase rate of the transmission torque decreases as the differential rotation speed increases.
The graph of FIG. 8 shows the relationship between the transmission torque and the differential rotation speed. In the power transmission device according to the above-mentioned prior application, as shown in graph (I), the viscous cup shown in graph (II) is shown. Since the viscosity of the viscous fluid decreases less with temperature than that of the ring, the rate of increase tends to decrease gradually, although the transmission torque increases compared to the coupling. Therefore, the torque transmission characteristics gradually deviate from the lower limit of the tight corner braking phenomenon occurrence region (III),
It is disadvantageous in terms of vehicle running performance.

Therefore, an object of the present invention is to address such a problem.

(Means for Solving the Problems) A power transmission device according to the present invention is disposed between both inner and outer rotating members that are coaxially and relatively rotatably positioned, and operates by the relative rotation of these both rotating members to cause viscous resistance. A viscous resistance generating means for generating a force, a friction clutch for generating a frictional engagement force that connects the rotating members so that torque can be transmitted, and a frictional clutch that increases or decreases the frictional engagement force according to the applied thrust, and the viscous resistance force. A pair of thrust converting means for converting a viscous resistance force generated by the generating means into a thrust force for the friction clutch, the thrust converting means being relatively rotated in accordance with the viscous resistance force generated by the viscous resistance force generating means. And a cam follower which is interposed between the cam surfaces of the cam members and acts to separate the cam members from each other. At least one of the cam members is constituted by a cam forming member having a cam surface and a cam body member having a recess into which the cam forming member is fitted, and the cam forming member is an elastic member. The cam body member is fitted into and supported by the recess of the cam body member.

(Operation and effect of the invention) In the power transmission device having such a configuration, when relative rotation occurs between both rotary members, a viscous resistance force is generated in the viscous resistance force generating means according to the differential rotation speed, and the viscous resistance force is generated. Is converted into thrust for the friction clutch by the thrust converting means. Therefore, the friction clutch is pressed by the thrust, and torque transmission proportional to the differential rotation speed is performed between the both rotary members. Therefore, the power transmission device functions as a connecting mechanism between the drive-side rotating member and the driven-side rotating member in one power-transmitting system path of the four-wheel drive vehicle, and also rotates between the drive-side and the driven-side rotating members and both drive-side rotating members. It functions as a differential limiting mechanism between the members and between the driven side rotating members.

Therefore, in the power transmission device, when the differential rotation speed between both rotary members increases and the relative rotation between both cam members increases, the action of the cam follower on one cam member in one direction of rotation and the other Of the cam member in the other rotational direction on the cam member is increased. Therefore, in the cam member having the cam forming member and the cam body member as its constituent members, the elastic member is deformed by the acting force in the rotational direction from the cam follower, and the cam forming member is inclined. The axial component force of the cam member increases in proportion to the inclination of the cam forming member, which increases the thrust generated by the thrust converting means. Therefore, the transmission torque increases,
By supplementing or exceeding the decrease in the transmission torque due to the decrease in the viscosity of the viscous fluid, in the power transmission device, the torque transmission characteristics can be brought close to the lower limit of the tight corner braking phenomenon occurrence region, It is possible to improve the running performance of the vehicle.

Further, in the power transmission device, the impact generated on the cam surface is mitigated by the elastic member interposed between the cam forming member and the cam body member, and the life of the device is improved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a power transmission device 10 according to a first embodiment of the present invention. As shown in FIG. 7, the power transmission device 10 is arranged in a rear-wheel power transmission system passage of a rial time type four-wheel drive vehicle.

In the vehicle, the front wheel side is always driven and the rear wheel side is driven when necessary. The transaxle 22 mounted on one side of the engine 21 is equipped with a transmission and a transfer, and the power from the engine 21 is transmitted to the axle shaft 23.
To drive the front wheels 24 and output to the first propeller shaft 25. The first propeller shaft 25 is connected to the second propeller shaft 26 via the power transmission device 10. When both shafts 25, 26 can transmit power, power is output to the axle shaft 28 via the rear differential 27. , The rear wheels 29 are driven.

The power transmission device 10 includes a friction clutch 10a, a viscous resistance generating means 10b, and a thrust converting means 10c in an annular working chamber composed of an outer case 11 and an inner case 12. The outer case 11 is integrally connected to a first propeller shaft 25, and the inner case 12 is integrally connected to a second propeller shaft 26 and is coaxially and relatively rotatably assembled in the outer case 11. .

The friction clutch 10a is a wet multi-plate clutch and is composed of a large number of clutch plates 13a and clutch discs 13b. Each clutch plate 13a has its outer spline part fitted to the inner spline part 11a of the outer case 11 to be integrated with the case 11. The clutch discs 13b are assembled so as to be rotatable and movable in the axial direction, and the inner spline portion of each clutch disc 13b is fitted to the outer spline portion 12a of the inner case 12 so as to be integrally rotatable with the same case 12 and movable in the axial direction. Is installed in.

The viscous resistance generating means 10b is a bottom portion 11b in the outer case 11.
And a viscous fluid chamber R formed by a first cam member 14 forming a thrust converting means 10c described later, and an outer case 11.
The first fin 11c provided on the bottom 11b of the first cam member 14 and the second fin 14a provided on the first cam member 14. The first fin 11c is made of a material such as aluminum alloy that is lighter in weight and easier to process than the outer case 11.
11 is a bottom 11b integrally rotatable with the casing 11 is fitted to the large number of fins 11c ₁ are coaxially protruded a predetermined length are formed concentrically viscous fluid chamber R. 2nd fin
14a is integrally formed on the body member 14b of the first cam member 14 comprises a first fin 11c the same aluminum alloy lightweight and easily processed material and a number of fins 14a ₁
Are formed concentrically and project coaxially from the fluid chamber R by a predetermined length. The first cam member 14 is assembled so as to be liquid-tightly rotatable and axially slidable with respect to both cases 11 and 12, and each fin portion 14a ₁ is a fin portion 11c ₁ of each first fin 11c. They are fitted with each other with a predetermined minute gap therebetween and are polymerized with each other for a predetermined length. The fluid chamber R is filled with a predetermined amount of highly viscous viscous fluid such as silicon oil.

The thrust converting means 10c is composed of a first cam member 14, a second cam member 15, and a plurality of rollers 16 which are cam followers. Thus, both cam members 14 and 15 are composed of cam body members 14b and 15a and cam forming members 14c and 15b. As shown in FIGS. 1 to 3, each of the cam body members 14b and 15a is provided with a plurality of recesses 14d and 15c formed on the surfaces facing each other at equal intervals in the circumferential direction. Cam forming members 14c and 15b are elastic members 14e and 1 made of rubber.
The recesses 14d and 15c are fitted and supported through the recesses 5d. Each cam formation member 14c, 15b is provided with a mutually pair of cam surfaces 14c on opposite sides _1, 14c ₂ and 15b _1, the cam portion of the V shape consisting 15b _2. The cam member 15 is integrally rotatably attached to the outer periphery of the inner case 12 between the first cam member 14 and the leftmost clutch disc 13b of the friction clutch 10a. Rollers 16 are interposed between the cam portions of the members 14, and the rollers 16 are in contact with the cam surfaces of the cam portions.

In the power transmission device 10 having such a configuration, when relative rotation does not occur between the first and second propeller shafts 25, 26, torque is not transmitted between these shafts 25, 26, but both shafts 25, 26 When relative rotation occurs between 26, torque is transmitted between both shafts 25, 26. That is, when relative rotation occurs between the shafts 25 and 26, the outer case 11 and the first fin 11 that are integral with the first propeller shaft 25 are formed.
Inner case 1 integrated with c and the second propeller shaft 26
2. Relative rotation occurs between the second cam member 15 and the second fin 14a, and a viscous shear torque T represented by the following formula is generated between the fins 11c and 14a.

K: constant, μ: viscosity of viscous fluid, N: differential rotation speed, l: length of each fin facing each other, h: gap between facing surfaces of each fin, r
i: Each radius of the viscous shearing force generating portion This viscous shearing torque T acts as a resistance for restricting the differential rotation of the first cam member 14, and this resistance F is
If the arrangement radius of 16 is R, then F = T / R. This resistance is converted into a thrust for pressing the friction clutch 10a by the thrust conversion means 10c.
15 and the roller 16 operate as shown in FIGS. 2 and 3, and the thrust S is S = Ftan θ, where θ is the contact angle between the roller 16 and each cam surface. As a result, in the friction clutch 10a, the clutch plate 13a and the clutch disc 13b are frictionally engaged according to the differential rotation speed, and torque is transmitted between both cases 11 and 12, that is, both shafts 25 and 26.

Therefore, in the power transmission device 10, as shown in FIG. 2, the force of the cam members 14 and 15 in the relative rotation direction is changed.
In the case of F ₁ is, F ₁ is the elastic member 14e for small forces, 15d
The deformation of is small and the thrust S ₁ is F ₁ tan θ ₁ . On the other hand, when the force in the relative rotation direction changes from F ₁ to F ₂ larger than F ₁ , the elastic members 14e and 15d are deformed as shown in FIG. 3 and the contact angle of each roller 16 with respect to each cam surface is θ ₁ Greater than θ ₂
And the thrust S _{2 in} this case is F ₂ tan θ ₂ . Therefore, in the power transmission device, a larger transmission torque can be obtained than the power transmission device in the earlier application because the contact angle θ increases, and the torque transmission characteristic has a tight corner braking phenomenon as shown in the graph (IV) of FIG. Area of occurrence (III)
The lower limit of is approached, and the running performance of the vehicle is improved.

In the present embodiment, only one of the cam members 14 and 15 may be composed of the cam body member and the cam forming member.

FIG. 4 shows a power transmission device 30 according to a second embodiment of the present invention.
The power transmission device 30 is also arranged in the rear-wheel power transmission system path of the rial time type four-wheel drive vehicle shown in FIG. 7 similarly to the power transmission device 10 according to the first embodiment. It

Thus, the power transmission device includes a viscous resistance generating means 30a, a friction clutch 30b, and a thrust converting means 30c in an annular working chamber composed of the outer case 31 and the inner case 32.

The outer case 31 includes an annular first outer shell 31a, a second outer shell 31b,
And the third outer shell 31c, the first outer shell 31a and the second outer shell 31
The second outer shell 31b and the third outer shell 31c are fixed to each other in a liquid-tight manner. The inner case 32 has a stepped tubular shape, and an outer case 31 is liquid-tightly and rotatably fitted to the outer periphery of the case 32, and a working chamber is formed by these cases 31 and 32. The inner case 32 is fitted and fixed to the spline at the tip of the second propeller shaft 26 by the inner spline 32a, and the outer case is
31 is rotatably supported by the tip of the shaft 26 and is
It is fixed to the rear end of the propeller shaft 25.

The viscous resistance force generating means 30a is composed of an operating plate 33 and a first cam member 34 which constitutes a thrust converting means 30c described later. The operating plate 33 is provided with a large number of concentric ribs 33a on one side thereof, is integrally rotatably attached to the outer periphery of the inner case 32, and is retained. The first cam member 34 has a large number of concentric ribs 34a on the other side, is fitted to the inner circumference of the first outer shell 31a of the outer case 31, and is liquid-tight and rotatable with respect to the inner case 32. It has become. In the first cam member 33, the ribs 34a are fitted between the ribs 33a of the actuating plate 33 with a predetermined circumferential interval.

The friction clutch 30b includes a number of clutch plates 35 and clutch discs 36. Each clutch plate 35 has a spline portion on the outer periphery of the second outer shell 31b of the outer case 31.
By fitting it to the spline portion 31d provided on the inner periphery of
It is attached to the case 31 so as to be integrally rotatable and movable in the axial direction. Each clutch disc 36 has a spline portion on the inner periphery thereof provided on the outer periphery of the inner case 32.
It is fitted between the clutch plates 35 and is positioned between the clutch plates 35, and is assembled to the case 32 so as to be integrally rotatable and movable in the axial direction. A predetermined amount of clutch oil is sealed in the storage chamber R ₁ of the plate 35 and the disc 36.

The thrust converting means 30c is composed of a first cam member 34, a cam mechanism including a first outer shell 31a forming a second cam member and a plurality of balls 37, and an operating piston 38. As described above, it also serves as a constituent member of the viscous resistance generating means 30a. The surface of the first outer shell 31a (which may be referred to as the second cam member 31a hereinafter) that constitutes the second cam member facing the first cam member 34 has a circumferential direction as shown in FIGS. A plurality of recesses 31a ₁ formed at the same intervals are formed, and a cam forming member 31e is fitted and supported in the recess 31a ₁ via a rubber elastic member 31f. There is. The cam forming member 31e and the cam forming member 34b of the first cam member 34 are provided with a V-shaped cam portion composed of a pair of cam surfaces 31e ₁ , 31e ₂ and 34b ₁ , 34b _{2 on the} sides facing each other, Each ball 37 is interposed in each cam portion. The working piston 38 is mounted on the inner circumference of the first outer shell 31a of the outer case 31 and the outer circumference of the inner case 32 so as to be liquid-tight and slidable in the axial direction.
A pressure chamber R ₂ is formed between 34 and the leftmost clutch disc 35, and the first cam member 34 accommodates the working plate 33. A predetermined amount of highly viscous fluid such as silicon oil is enclosed in the pressure chamber R ₂ and also serves as a chamber for generating a viscous resistance force.

In the power transmission device 30 having such a configuration, the first and second
When relative rotation does not occur between the propeller shafts 25 and 26, torque is not transmitted between the shafts 25 and 26, but when relative rotation occurs between the shafts 25 and 26, torque is transmitted. That is, when a relative rotation occurs between the two shafts 25, 26, the outer case 31, which is integrally rotatably assembled to the first propeller shaft 25, the second cam member 31 a and the first cam member 34, which are integrated with each other, , Differential rotation occurs between the inner case 32 and the working plate 33 that are integrally rotatably mounted on the second propeller shaft 26, and viscous friction between the working plate 33 and the first cam member 34 is given by the following formula. Torque T is generated.

Where k is a constant, μ is the viscosity of the viscous fluid, N is the operating speed, l is the length of each rib facing each other, h is the distance between the facing surfaces of each rib, and ri is each radius of the viscous shearing force generator. The viscous friction torque T acts as a resistance force that restricts the differential rotation of the first cam member 34, but the resistance force F of each ball 37 is T / R (R is the raceway ring radius of the ball 37). Further, this resistance force F causes the first cam member 34 to move to the pressure chamber.
Converted to thrust to slide to the R ₂ side, but in this case the ball
The contact angle θ of each cam surface of 37 is for both cam members 34, 31.
When the force of a in the relative rotation direction increases, the elastic member 31f is deformed as shown in FIG. 6 to increase the contact angle of the ball 37 on the cam forming member 31e side. Therefore, also in the power transmission device 30, the same operational effects as the power transmission device 10 in the first embodiment are exhibited.

In each of the above-described embodiments, the example in which the roller 16 or the ball 37 is adopted as the cam follower is shown. However, instead of the roller 16 or the ball 37, the cam follower is integrally formed on either one of the cam members. You may change to.

[Brief description of drawings]

FIG. 1 is a sectional view of a power transmission device according to a first embodiment of the present invention, FIGS. 2 and 3 are enlarged sectional views of a cam portion of the device, and FIG. 4 is a power transmission according to the second embodiment. Sectional views of the apparatus, FIGS. 5 and 6 are enlarged sectional views of a cam portion of the apparatus, FIG. 7 is a schematic configuration diagram of a vehicle equipped with the power transmission apparatus according to the first embodiment, and FIG. It is a graph which shows the relationship between dynamic rotation speed and transmission torque. Explanation of reference numerals 10, 30 ... Power transmission device, 10a, 30a ... Friction clutch,
10b, 30b ... Viscous resistance generating means, 10c, 30c ... Thrust converting means, 11, 31 ... Outer case, 12, 32 ... Inner case, 14, 34 ... First cam member, 15, 31a ... … Second
Cam member, 14b, 15a ... Cam body member, 14c, 15
b, 31e, 34b ... Cam forming member, 14e, 15d, 31f ... Elastic member, 16 ... Roller, 37 ... Ball, 25,26 ... Propeller shaft.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Watanabe 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation (56) Reference JP-A-1-206126 (JP, A)

Claims (1)

(57) [Scope of utility model registration request] 1. A viscous drag force generating means which is disposed between inner and outer rotary members coaxially and relatively rotatably positioned to operate by relative rotation of these rotary members to generate a viscous drag force; A friction clutch that generates a frictional engagement force that connects the members in a torque-transmittable manner and that increases or decreases the frictional engagement force according to the applied thrust, and a viscous resistance force generated by the viscous resistance force generation means to the friction clutch. A thrust converting means for converting into a thrust, the thrust converting means is provided between a pair of cam members that relatively rotate in accordance with the viscous resistance force generated by the viscous resistance generating means, and between the cam surfaces of these cam members. A power transmission device comprising a cam follower interposed so as to act to separate both cam members from each other, wherein at least one cam member of said both cam members. The bar is composed of a cam forming member having a cam surface and a cam body member having a recess into which the cam forming member is fitted, and the cam forming member is fitted into the recess of the cam body member via an elastic member. The power transmission device is characterized by being supported by.