JPH01190539A - Power transmitting device of four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To always obtain suitable transmission torque according to a car velocity by interposing resistance adjusting means between one of front and rear wheels and a fluid coupling, and increasing and decreasing resistance for regulating relative rotation therebetween according to a car velocity. CONSTITUTION:A four-wheel vehicle 1 includes a front axle 3 connected to a front wheel 2, and an engine 4 and a transmission 5 are respectively disposed in front of the front axle 3. A transfer 6 is interposed above the front axle 3. Further, a rear axle 8 connected to rear wheels 7 is provided, and a rear differential gear 9 is interposed above the rear axle 8. Further, a viscous coupling 10 as a fluid coupling is interposed between the transfer 6 and the rear differential gear 9. In the above constitution, means 16 for adjusting the increase and decrease of resistance for regulating the relative rotation between the viscous coupling 10 and the transfer 6 is interposed therebetween.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a power transmission device for a four-wheel drive vehicle.

(Prior art) For power transmission devices of four-wheel drive vehicles, Japanese Patent Application Laid-Open No. 60-1727
As shown in Publication No. 64, a power source is linked to one side of the front and rear wheels, and one side of the front and rear wheels is linked to the other side of the front and rear wheels via a fluid coupling. There is. In the power transmission system of such a four-wheel drive vehicle, normally only one side of the old or rear wheels is directly driven by the power source, but when turning, the difference in rotational speed between the front and rear wheels is When this occurs, power is transmitted from one side of the front and rear wheels to the other side of the front and rear wheels via the fluid coupling.

(Problem to be Solved by the Invention) However, in the power transmission system of a four-wheel drive vehicle, when a difference in rotational speed occurs between the front and rear wheels, regardless of the vehicle speed, the fluid coupling Since the same transmission torque is transmitted so that the difference in rotation speed between the front and rear wheels is reduced, driving stability is improved when turning at high speeds, but when turning at low speeds, A braking phenomenon is supposed to occur. Therefore, the amount of transmitted torque generated by the fluid coupling is required to be appropriate depending on the vehicle speed state.

The present invention has been made in view of the circumstances described in 1- above, and an object of the present invention is to provide a power transmission device for a four-wheel drive vehicle that can obtain an appropriate amount of transmitted torque depending on the vehicle speed state.

(Means for solving the problem 1) In the present invention for achieving the above object, a power source is connected to one side of the front and rear wheels, and a power source is connected to one side of the front and rear wheels. i? 1. The other side of the rear wheel is linked via a fluid coupling, and the fluid coupling generates a transmission torque proportional to the rotation speed difference when a rotation speed difference occurs between the front and rear wheels. In a power transmission device for a four-wheel drive vehicle, a resistance adjustment means is interposed between one side of the front and rear wheels and an input part of the fluid coupling, and the resistance adjustment means adjusts the resistance as the vehicle speed increases or decreases. The configuration is configured to increase or decrease relative rotation regulating resistance between one side of the front/rear wheels and an input portion of the fluid coupling.

With the above-mentioned configuration, at each vehicle speed, a difference in rotational speed occurs between the front wheels and the rear wheels, and a transmission torque is generated, and the transmitted torque is transmitted between one side of the front wheels and the rear wheels and the input part of the fluid coupling. When the relative rotation regulating resistance between the two is exceeded, the two rotate relative to each other, and no further transmission torque is generated. Therefore, for each vehicle speed, the maximum transmission torque (transmission torque capacity) can be obtained in direct proportion to the vehicle speed, and an appropriate amount of transmission torque can be obtained depending on the vehicle speed.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 to 4, 1 is a four-wheel drive vehicle, and a front axle 3 connected to the front wheels 2 is disposed on the front side of the four-wheel drive vehicle 1, and further forward of the vehicle body than the front axle 3. An engine 4 and a transmission B95 are disposed in the front axle 3, and a transfer 6 including a front differential etc. is installed in the front axle 3. The power from the engine 4 is transmitted to the transmission 5, the transfer 6, and the front axle 3. The signal is transmitted to the front wheels 2 via the . On the other hand, a rear axle 8 connected to a rear wheel 7 is disposed on the rear side of the four-wheel drive vehicle 1, and a rear differential 9 is interposed on this rear axle 8.

A viscous coupling 10 as a fluid coupling is interposed between the transfer 6 and the rear differential 9. The viscous coupling lO is, as shown in Figure 2,
The fluid coupling includes an outer case 11 as a manual part and an output shaft 12 as an output part. The outer case 11 includes a cylindrical portion 11a, a partition 11b that closes one end of the cylindrical portion 11a, and a partition 11c that closes the other end of the cylindrical portion 11a.
b is disposed a little more inward in the axial direction of the cylindrical portion 11a than one end of the cylindrical portion +1a. The output shaft 12 has one end thereof passing through both corner walls 11b and llc in a liquid-tight manner so as to be relatively rotatable, and the other end of the output shaft 12 is linked to the rear differential 9 side. An internal space 13 is formed between the output shaft 12 and the outer case 11, and oil is sealed in the internal space 13.
In the above, a plurality of outer plates I4 are fitted to the inner circumferential surface of the outer case 11 in a relatively non-rotatable manner, and a plurality of -r inner plates 15 are fitted to the outer circumferential surface of the output shaft 12 in a relatively non-rotatable manner, The outer plates 14 and the inner plates 15 are arranged alternately. As a result, when a difference in rotational speed occurs between the front and rear wheels 2.7, there will be a difference in rotational speed between the outer case 11 and the output shaft 12, and this will occur at the same time as the inner plate 15 and the outer plate! Based on the viscosity of the oil in the internal space 113, the transmitted torque caused by the plate with a high rotation speed pulling the plate with a low rotation speed is as shown in the characteristic line in Figure 4. This occurs in proportion to the difference in rotational speed.

A resistance adjustment mechanism 16 as a resistance adjustment means is provided between the front viscous coupling 10 and the transfer. This resistance adjustment mechanism 16 is composed of a rotating plate 17 on a slightly thick disk, a plurality of balls 18, and a plurality of springs 19. Rotating plate I
7 is loosely fitted from the outside to the outer periphery on the negative end side or the inner periphery on one end side of the inner cylinder portion 11a of the outer case 11, and the other end side is connected to the transmission shaft 20 extending from the transfer 6. A protrusion +7a is provided at the axial center of one end of the rotary plate 17, and the protrusion 17a is rotatably supported by the partition wall 17b and one end of the output shaft 12 via bearings 21 and 22. There is. A plurality of ball holding holes 23 are formed on the outer periphery of one end of the rotary plate 17 . The plurality of ball holding holes 23 are arranged at regular intervals in the circumferential direction of the rotating plate 17, and each ball holding hole 23 extends in the radial direction of the rotating plate 17. A plurality of balls I8 are housed in each ball holding hole 23, and each ball 18 is movable within each ball holding hole 23 in the direction in which the ball holding hole 23 extends. A plurality of springs 19 are housed in each ball holding hole 23 and interposed between the ball 18 and the rotating plate 17, and each ball 18 has a portion thereof released from each ball holding hole 23 by each spring 19. It protrudes slightly and is lightly pressed against the inner peripheral surface of the inner cylinder part lla of the outer case 11.

A plurality of slightly recessed ball receiver portions 24 are formed on the inner peripheral surface of one end side of the inner cylinder portion 11a of the outer case 11. The plurality of ball receivers 24 are connected to the inner cylindrical portion le.
They are provided corresponding to the ball holding holes 23 in the circumferential direction of a, and each ball receiving portion 24 can receive the ball 18.

Therefore, according to the above configuration, the rotational speed of the rotating plate 17 increases or decreases in response to an increase or decrease in the vehicle speed, and the centrifugal force acting on each ball 18 also increases or decreases in response to an increase or decrease in the rotational speed of the rotating plate 17. I will do it. Therefore, the pressing force with which each ball 18 is pressed against each ball receiver part 24 is determined according to the vehicle speed.
The relative rotation regulating resistance between the rotating plate 17 and the outer case 11 increases or decreases in proportion to increases or decreases in vehicle speed.

As a result, in this embodiment, from the low speed range to the medium speed range (
10 to 40 km/h), when the transmitted torque exceeds the relative rotation regulating resistance between the rotating plate 17 and the outer case L at each vehicle speed, each ball 18 The rotating plate 17 is pushed into each ball holding hole 23 against the force, and the rotating plate 17 rotates relative to the outer case 11. As a result, no more transmission torque is generated from the low speed range to the medium speed range, and the maximum transmission torque (transmission torque capacity @) that is directly proportional to the vehicle speed is determined for each vehicle speed.

FIG. 4 shows an example of the cut line of the maximum transmission torque, and as the vehicle speed increases, the cut line moves to the side where the transmission torque is large.

On the other hand, in the high-speed range, the relative rotation regulating resistance between the rotating plate 17 and the outer case II is set so that it cannot be rotated by the transmitted torque. It is now impossible to do so. Therefore, in this vehicle speed range, the transmitted torque is obtained based on the characteristic line shown in FIG. 4 as before without the torque being cut midway.

As a result, when turning at low speeds, the amount of transmitted torque can be reduced to prevent braking phenomena from occurring, and when turning at high speeds, the amount of transmitted torque can be maintained in a large state to ensure driving stability as before. You will be able to do that. In this way, it is possible to obtain an appropriate amount of transmitted torque depending on the vehicle speed.

5 to 8 show other embodiments. In this embodiment, the same components as those in the previous embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, mounting pieces 25 made of a shape memory alloy are mounted so as to protrude from the inner circumferential surface of the outer plate 14 and the outer circumferential surface of the inner plate 15, as shown in FIGS. 5 to 7. , when the temperature is below a predetermined temperature (low temperature), the protrusion 25a of the mounting piece 25 is collapsed as shown by the imaginary line in FIG. It is designed to stand up.

Generally, the transmission torque characteristics of a viscous coupling decrease as the temperature of the oil in the viscous coupling increases, and the transmission torque capacity of the viscous coupling 10 changes. , this is suppressed from a predetermined temperature or higher, as shown in FIG.

In FIG. 8, the characteristic line indicated by the thick line is related to this example.
The characteristic line f1 shows the temperature characteristics of the oil in the viscous coupling 10 when the protrusion 25a of the mounting piece 25 is upright, and the characteristic line f2 shows the temperature characteristic of the oil in the viscous coupling 10 in the conventional case where the mounting piece 25 is not attached. The temperature characteristic of oil, the characteristic line f3 is the transmitted torque characteristic when the protrusion 25a of the mounting piece 25 is upright, the characteristic line f4 is the transmitted torque characteristic in the conventional case where the mounting piece 25 is not attached, and the point A is the transmitted torque The characteristic change starting point, point B, indicates the temperature at which the shape of the mounting piece 25 starts changing.

(Effects of the Invention) As described above, the present invention can obtain an appropriate transmission torque (2) depending on the vehicle speed.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing a four-wheel drive vehicle according to the present invention, Fig. 2 is an enlarged longitudinal cross-sectional view of main parts showing a power transmission device according to the present invention, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. 4 is a diagram showing the cut line of the maximum transmission torque at each vehicle speed, and FIG. 5 is a partial sectional view showing a viscous coupling according to another embodiment. Fig. 6 is an explanatory diagram for explaining the attachment of the mounting piece to the inner plate, Fig. 7 is an explanatory diagram for explaining the operating state of the mounting piece, and Fig. 8 is the transmission torque of the viscous coupling versus time, and the relationship between the transmission torque in the viscous coupling and FIG. 3 is a characteristic diagram showing the relationship between oil temperature and time. I: 4 wheels 2: Front wheel 4: Engine 7: Rear wheel IO: Viscous coupling 16: Resistance adjustment mechanism Patent applicant Mazda Motor Corporation Figure 1 Figure 2 Figure 3 Figure 4 shows the rotation speed Envy (r, p, m,) N Fig. 5 Fig. 7 Fig. 6 Fig. 81m Shizutsuta →

Claims (1)

[Claims] (1) A power source is linked to one side of the front/rear wheels, one side of the front/rear wheels is linked to the other side of the front/rear wheels via a fluid coupling, and the fluid coupling is connected to the front/rear wheels. - In a power transmission device for a four-wheel drive vehicle that is configured to generate a transmission torque proportional to the rotation speed difference when a rotation speed difference occurs between the rear wheels, one side of the front and rear wheels and the fluid A resistance adjustment means is interposed between the input part of the joint, and the resistance adjustment means adjusts the relative rotation between one side of the front/rear wheels and the input part of the fluid joint as the vehicle speed increases or decreases. A power transmission device for a four-wheel drive vehicle, characterized in that the power transmission device is set to increase or decrease regulating resistance.