JPS63111323A - Viscous coupling with variable displacement device - Google Patents

Abstract

PURPOSE:To prevent the tight corner braking, by making a one end wall of a casing be axially movable by external operation, and thereby changing the torque transmitting characteristics. CONSTITUTION:In the case of selecting a hump mode from a viscous mode, a fork 16 is moved in the direction of arrow a to thereby outwardly raise a moving piece 9 along a guide groove 10 by means of a link 17 and axially inwardly urge a piston 8 through an inclined surface 11. An amount of movement of the piston 8 is set to be within a compressible area of compressive fluid stored in a viscous coupling A. Accordingly, the movement of the piston 8 causes an increase in inner pressure to change a viscous fluid density. As a result, a transmitting torque is increased to change the characteristics of the viscous mode. Therefore, it is possible to prevent tight corner braking under a normal condition.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to a viscous coupling used as a differential thrust limiting device of an automobile or a power transmission device of a propeller shaft that connects the front and rear axles of a 4WD width. The present invention relates to a viscous coupling equipped with a variable capacitance device that changes the capacitance in order to make the viscous mode characteristics variable by changing the capacitance. BACKGROUND OF THE INVENTION As shown in FIG. 8, a conventionally used viscous coupling includes a plurality of inner plates 4, 4, and 4 spline-coupled to an input shaft 2 and an output shaft 3, respectively, in a sealed casing, as shown in FIG. It has a structure in which outer plates 5 are arranged alternately and a viscous fluid 6 such as high viscosity silicone oil and air 7 are sealed inside. In other words, the viscous mode is torque transmission due to the shear resistance of the viscous fluid, and when a rotational speed difference occurs between the two plates 4,512!1, the shear resistance of the viscous fluid 6 increases. Input shaft 2
Torque is transmitted from the input shaft to the output shaft 3, but in this viscous mode, slip loss occurs between the input and output shafts 2 and 3. In the hump mode, power is transmitted by the frictional force between both plates 4.5, and in the viscous mode, the viscous fluid 6
As the stirring continues, the internal temperature rises, the viscous fluid 6 compresses the air 7 present inside and expands, and when the internal volume of the casing 1 becomes full, the outer plate 5 moves toward the inner plate 4 side with a sudden pressure rise. They move and come into close contact, and are pressed against each other by internal pressure, and the output shaft 2.3 is directly connected to transmit torque. Incidentally, as a prior art related to such a viscous coupling, Japanese Utility Model Application Publication No. 59-188731 can be found.

[The same ff1al that the invention attempts to solve, therefore, 4WD
*Instead of using a dog clutch as a transfer clutch or using a variable transmission torque type wet multi-disc hydraulic clutch as shown in JP-A No. 56-4303, A viscous coupling having the characteristics described above can be used in a differential limiting device of an automobile as shown in Fig. 9, or a power transmission device between the front and rear axles of a 4WD vehicle as shown in Fig. 10. are increasing. However, with the normally used viscous coupling, the characteristics change depending on the temperature, such as immediately after the start of operation and during warm-up, or between summer and winter, so the power transmission is constant depending on the difference in rotational speed between the front and rear wheels. There is the problem that the characteristics cannot be obtained, and in order to avoid the braking phenomenon at tight corners, setting the torque characteristics in viscous mode small in the low rotation speed difference area, 4WD due to insufficient rear wheel torque
There is a problem in that the performance in Itl and b cannot be fully demonstrated. In addition, in order to avoid sudden changes in the characteristics during normal driving, if you set the settings so that the hump mode is not reached under normal driving conditions, the hump mode will be used in case of an emergency escape from a stuck car that is stuck in the sand or spinning. When necessary, it was difficult to set an appropriate viscous coupling capacity, such as the time it took to reach hump mode. In FIGS. 9 and 10, E indicates the engine, M the transmission, B the viscous coupling, FD the front differential, and RD the rear differential. The present invention has been made in view of the above-mentioned circumstances, and by varying the capacitance in the viscous coupling and changing the viscous mode characteristics according to the driving conditions, 4WD
The present invention provides a viscous coupling equipped with a variable capacity device for the purpose of improving the torque characteristics of a viscous coupling for automobiles. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of plates that are engaged with the input shaft and the output shaft at predetermined intervals, respectively, in a sealed casing. In a viscous coupling in which air is mixed with a viscous fluid such as silicone oil having a viscosity of 100% viscosity and air is mixed and sealed inside the casing, one end side wall of the casing is installed to be movable in the axial direction, and the side wall A means for moving the side wall by external operation is provided that can be moved in multiple stages in a compressible region of compressible fluid such as air sealed inside the casing, and the means for moving the side wall by external operation is fixed so that it is not pushed back by internal pressure. It is structured by providing means.

[Function] Based on the above structure, the present invention provides a viscous coupling in which one end side wall of the casing is made movable in the axial direction by means of externally operated movement means, and the viscous coupling is enclosed in the casing of the viscous coupling. By compressing compressible fluid such as air within the compressible region, it is possible to age the internal pressure and change the torque transmission characteristics. Therefore, the viscous coupling equipped with the variable displacement device according to the present invention prevents tight corner braking by changing the torque transmission characteristics, and
4WD! Greatly reduces the time it takes to reach hump mode when stuck, allowing for a quick escape! It is possible to improve the performance of II.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is a longitudinal sectional view of a viscous coupling showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line II-■ in Fig. 1, and Fig. 3 is a sectional view showing a state in which the internal pressure of the viscous coupling is increased. It is a diagram. - In the figure, symbol A is a viscous coupling, 1 is a sealed casing, 2 is an input shaft 3 is an output shaft, and the input shaft 2. A plurality of inner plates 4 and outer plates 5, each of which is engaged with a spline or the like, are arranged at predetermined intervals on the output shaft 3, and the inside contains a viscous fluid 6 such as high viscosity silicone oil and air. A compressible fluid such as 1 is enclosed. A piston 8 is provided on one end side wall of the casing 1 and is slidable within the casing 1 by a moving means B. The moving means B has the following configuration. That is, a radial guide groove 10 is formed on the outside of the piston 8 so that the plurality of pieces 9 can slide only in the radial direction. Further, the piston 8 and the piece body 9 have a piece body 9.
An inclined surface 11 is formed so that when the piston 8 moves outward, the piston 8 can be pushed in the axial direction. Furthermore, a guide plate 12 is installed at the inner end of the casing 1 to prevent the piece body 9 from being pushed outward when the piece body 9 pushes the piston 8 inward. The guide plate is positioned by a snap ring 13 for fixing the guide plate. A shaft 15 rotatable on the input shaft 2 is integrally formed on the guide plate 12, and a sleeve 1 is mounted on the shaft 15.
4 is slidably fitted through the spline, and the sleeve 1
4 is moved by a fork 16. Further, the inner end of the sleeve 14 and the piece body 9 are connected by a link 17 and are pivotally supported via a pin 18. When the sleeve 14 is pushed in by a fork 16, the piece body 9 is guided by the link 17. The piston 8 can be slid in the radial direction along the groove 10 to push the piston 8 inward in the axial direction. Here, the fork 16 can be moved in the direction of arrow a by a lever on a driver's seat (not shown), and can be returned to its original position by operating the lever. However, since an excessive operating force is required to move the fork 16 in the direction of arrow a when the pressure inside the viscous coupling A is high, the fork 16 does not move even if the lever on the driver's seat is operated. Therefore, the moving means B is provided with a waiting mechanism C configured to automatically move after the internal pressure of the viscous coupling A has decreased. The holding mechanism C installed in the means B for moving the piston 8 by operating the external lever will be described below. FIG. 4 shows an embodiment of a slide rail system, in which the fork 10 is slidably installed on a slide rail 20, and a fixing ring 21. The left end has a structure in which a coil spring 22 is biased, and the slide rail 20
A positioning groove 20a for the viscous mode position and a positioning groove 20b for the hump mode position are formed in the ball 20.
Positioned by c. and slide rail 20
W1 moves in conjunction with the driver's seat lever 19. Therefore, when the internal pressure is high, operate the driver's seat lever 19 to
6 in the direction of arrow a, the fork 16 stops and only the slide rail 20 moves. Therefore, when the pressure inside the viscous coupling A decreases, the balance with the coil spring 22 is lost, and the fork 16 is pushed in the direction of arrow a by the coil spring 22. In this embodiment, two-stage movement having positions in the viscous mode and hump mode is used, but the present invention is not necessarily limited to this. FIGS. 5 and 6 show a rotary lever type, in which the fork 16 is rotatably engaged on the shaft 23, and the sleeve 1 is rotatably engaged with the shaft 23.
A slide piece 24 rotatable with respect to the fork 16 is installed at the engagement portion with the fork 4. A pin 25 is installed on the shaft 23 so as to be able to rotate together with the shaft 23, and is engaged with the long groove 27 of the fork 16. Further, a torsion coil spring 28 is installed on the shaft 2G with one end engaging the shaft 23 and the other end engaging the fork 16. Furthermore, a link lever 29 is installed at one end of the shaft 23 so as to be rotatable in conjunction with the driver's seat lever 19. FIG. 7 shows a structure in which an actuator that utilizes negative pressure in the engine suction pipe is added to the holding mechanism C according to the present invention shown in FIG.
32 is a solenoid valve, 32 is a switch, 33 is an engine, and 34 is a suction pipe.-0 Note that a description of the operation of the holding mechanism C shown in FIGS. 5 to 7 will be omitted. Next, the operation of the viscous coupling A constructed as described above will be explained based on FIGS. 1 to 3. When attempting to switch the viscous coupling A from the viscous mode (slip state) to the hump mode (directly connected state), first move the fork 16 in the direction of arrow a, and then the bridge body 9 moves into the guide groove via the link 17. 10 and pushes the piston 8 inward in the axial direction with the inclined surface 11. The amount of movement of the piston 8 is set within a compressible range of a compressible fluid such as air sealed inside the viscous coupling A. Here, the transmission torque TVρ−f(
t, p), and f(t, r, ν0). In addition, K1: Constant N1: Number of working plate surfaces ρ: Viscous fluid density ΔN: Input/output shaft rotational speed difference C: Kinematic viscosity coefficient of viscous fluid C: 111 distance between both plates r1 Nibrate inner radius ra = Mini plate diameter t: Temperature "Nibrating action radius"; Initial viscosity coefficient of the viscous fluid P: Pressure inside the casing. Therefore, as the piston 8 moves, the internal pressure P increases, the viscous fluid density changes, and the transmitted torque increases. Also, since the piston 8 is moved by the moving means B,
Since the internal volume of the casing 1 is reduced, the hump mode can be reached in a short time.

【Effect of the invention】

As explained in detail above, according to the present invention, in a viscous coupling, one end side wall of the casing is moved in the axial direction by an externally operated moving means to change the internal pressure, thereby changing the torque transmission characteristics of the viscous coupling. It is possible to achieve the following effects as a 4WD vehicle. ■ The characteristics of the viscous mode can be changed, so under normal conditions the setting emphasizes avoiding tight corner braking, and when the internal pressure is low, the setting is 4W.
Heavy rear wheel drive power as D. Various settings are possible. ■ By reducing the internal volume of the casing during stacking, the time to reach hump mode is shortened,
A quick escape is possible. ■ Changes in characteristics due to temperature can be prevented by using the normal state or the state with reduced internal pressure depending on whether it is cold or warm-up, or winter or summer.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a viscous coupling showing one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG.
The figure is a sectional view showing a state in which the internal pressure of the viscous coupling is increased, FIG. 4 is a schematic configuration diagram of the main part showing the waiting mechanism according to the present invention, and FIG. 5 is a main part showing another holding mechanism according to the present invention. 6 is a cross-sectional view taken along the line ■-■ of FIG. 5, FIG. 7 is a schematic diagram of the main parts showing still another holding mechanism according to the present invention, and FIG. 8 is a diagram showing a conventional viscous coupling. 9 is a schematic plan view showing a case where a conventional viscous coupling is used in a differential limiting device of an automobile. FIG. FIG. 3 is a schematic plan view showing the case where the device is used in a transmission device. A... Viscous coupling, B... Transportation means, C
...Holding mechanism, 1...Casing, 2...Input shaft, 3...Output shaft, 4...Inca plate, 5...
Outer plate, 8... Piston, 9... Piece body, 1
0... Guide groove, 11... Inclined surface, 12... Guide plate, 13... Snap ring, 14... Sleeve, 1
5... Axis, 16... Fork, 11... Link,
18... Bin, 19... Driver's seat lever, 20...
Slide rail, 21...fixing ring, 22...coil spring. Figure 1 ■ Figure 2 Figure 5 187 Figure 81! F Figure 9 Figure 10

Claims (2)

[Claims] (1) Inside a sealed casing, a plurality of plates are arranged alternately that are engaged with the input shaft and the output shaft at predetermined intervals, and inside is a viscous fluid such as high viscosity silicone oil and air. In a viscous coupling formed by mixing and enclosing a mixture of A viscous membrane equipped with a variable capacity device, characterized in that the step is provided with a means for moving the side wall by external operation, and a fixing means is provided so that the means for moving the side wall by external operation is not pushed back by internal pressure. Coupling. (2) In the externally operated moving means, a holding mechanism is provided in which when the internal pressure is higher than a set value, the side wall does not move and only the external operating lever moves. Viscous coupling with variable capacity device.