JPH0349307Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a power transmission device for an automobile.

[Prior Art] Conventionally, as a device for transmitting power from one input element to two output elements, for example, the one disclosed in Japanese Patent Application Laid-Open No. 58-50349 is known.

Power transmission between each element of this device is achieved by a plurality of rotary plates engaged with each element,
This is achieved by the viscous resistance of the viscous fluid between the rotating plates, and is a so-called viscous fluid coupling mechanism.

The viscous fluid coupling mechanism allows differential movement for relatively small differences in rotational speed and rate of change, and limits differential movement for relatively large differences in rotational speed and rate of change.

[Problems to be solved by the invention] In such a power transmission device, for example, when one wheel is spinning when driving in mud, the vehicle tries to escape with only one wheel, and differential rotation occurs between each rotary plate. get up. Since this differential is provided by the sliding between the rotary plates, if the differential continues, the temperature of the viscous fluid will rise, causing deterioration of the viscous fluid and deterioration of the sealing member. Additionally, the increased pressure within the coupling may result in damage to the sealing member.

In this case, by locking the casing with a known pneumatic actuator, it is possible to eliminate the differential and suppress the increase in internal pressure.

However, the known means has the disadvantage that the device becomes larger and more complicated because it includes an air actuator and other operating mechanisms.

Therefore, the object of this invention is to provide a power transmission device that can suppress the differential in response to the internal pressure of the viscous fluid coupling, suppress the increase in internal temperature and internal pressure, and can be made more compact.

[Means for Solving the Problems] In order to achieve the above object, this invention includes a rotatable case in which the rotational power of the case is transmitted through a viscous fluid coupling and a common axis. first and second power take-off sleeves having a rotation center are provided, and the first and second power take-off sleeves resist biasing springs respectively provided between the case and both sleeves when internal pressure of the viscous fluid coupling increases; groove means for conducting viscous fluid between the two sleeves so that the sleeves are moved in the axial direction, and a clutch portion that engages the two sleeves by movement by the groove means is provided in at least a portion of the viscous fluid coupling. There is.

[Function] In this power transmission device, when the vehicle is traveling straight, torque transmission is ensured between the first and second power take-off sleeves via a pair of symmetrically provided viscous fluid couplings. Next, for example, if the wheel on one side of the first power take-off sleeve falls into mud and starts idling, the second power take-off sleeve is
Attempts to escape using only torque transmission from the power take-off sleeve. Hereinafter, in cases such as off-road driving, even if the wheels are spinning, the vehicle can be driven using only one of the viscous fluid couplings. On the other hand, if the required torque is larger than the viscous torque, the torque transmission due to the sliding of the rotating plate continues for a long time, and the internal pressure of the viscous fluid coupling increases as the temperature rises. As a result, the first and second power take-off sleeves move due to internal pressure, and the movement of the sleeves activates the clutch section, and the case and the first and second power take-off sleeves are locked by the frictional force of the rotary plate, allowing direct torque transmission. Secured. Heat generation within the viscous fluid coupling is suppressed, preventing deterioration of the viscous fluid and the sealing member. Therefore, abnormal increase in internal pressure is suppressed, and damage to the sealing member can be prevented.

[Embodiment] Hereinafter, an embodiment of the invention will be described in detail with reference to the drawings of FIGS. 1 and 2.

In the figure, 1 indicates a differential case (case) of a power transmission device 7 that transmits power from the engine to left and right wheels. Power from an engine is input to the differential case 1 via a ring gear (not shown).

Inside the differential case 1, a pair of first and second power take-off sleeves 9, 11 that are rotatable about a common axis W are disposed, and are supported in the axial direction (left and right in FIG. 1) by bearings 13, 13. It is movably supported against biasing springs 31, 31.

The power of the differential case 1 is transmitted to the first and second power take-off sleeves 9 and 11 through viscous fluid couplings 15 and 17.

The viscous fluid couplings 15, 17 are seal members 19, 19 provided on the bearings 13, 13.
It has a sealed chamber that communicates with each other, and a plurality of rotary plates 21 and 23 arranged alternately in a maze-like manner, and the sealed chamber is filled with a viscous fluid such as silicone oil. One rotary plate 23 in the sealed chamber has a spline 25 formed on the outer peripheral surface of the first and second power take-off sleeves 9 and 11.
and the other rotary plate 21
is movably engaged with a spline 27 formed on the inner circumferential surface of the differential case 1, and viscous fluid acts on each rotating plate 21, 23.

A centering member 20 that engages with the differential case 1 is provided on the outer periphery of the opposing portions of the first and second power take-off sleeves 9 and 11. In addition, the first
Grooves 9a and 11a serving as groove means are bored in opposing surfaces of the second power take-off sleeves 9 and 11, so that viscous fluid can flow therein. The centering member 20 has a width that is approximately the same as the entire facing width of the sleeves 9 and 11, and the fluid in the sealed chamber flows from the gap between the rotary plates to the grooves 9a and 11a through the inner diameter groove 20a of the centering member 20 and pressurized oil. 1, the sleeves 9 and 11 are actuated to move symmetrically (separate) in opposite directions from the state shown in FIG. It is something to do.

The rotating plates 21 and 23 are press plates 29 and 29 provided on the first and second power take-off sleeves 9 and 11.
By being pressed in the axial direction (arrow F in FIG. 1) by the clutch members K, they function as clutch parts K, K that come into close contact with each other.

The fastening force between the rotary plates 21 and 23 is set by the thrust F acting in the axial direction, and the thrust force F is given by the formula F=d ² /4×π×p.

Here, d: diameter of the first and second power take-off sleeves (d is equal to the inner diameter of the sealing member 19,
When the sleeves 9, 11 receive pressure at their abutting surfaces, the effective diameter is obtained by subtracting the shoulder diameter which becomes ineffective. ) p: Pressure when the temperature of the viscous fluid increases The temperature of the viscous fluid increases as the sliding due to the relative rotation of the rotary plates 21 and 23 continues, and as a result of the increase in internal pressure, the above-mentioned thrust force is generated. When the differential stops and the heat generation subsides, the internal pressure decreases and the thrust force decreases, so the first and second power take-off sleeves 9, 11 are activated by biasing springs 31, 31 provided inside the bearings 13, 13. They return to the inside (the side opposite to the thrust force F) and come into contact with each other. In addition, in FIG. 1, D is the average effective diameter of the clutch portion K.

In the device configured in this way, when the vehicle is traveling straight, torque is transmitted to the first and second power take-off sleeves 9, 11 by the viscous fluid couplings 15, 17. Next, since the differential rotation is small, the torque during turning is allowed by the rotary plates 21 and 23 that rotate relative to each other against the resistance of the viscous fluid, making it possible to turn without any trouble.

On the other hand, for example, if the wheel on the side of the first power take-off sleeve 9 falls into mud and spins idle, it tries to escape using only the other viscous fluid coupling 17.
When the left and right wheels spin, the vehicle can escape from the mud by coupling only the viscous fluid on the wheels that are not spinning. However, under such conditions, when torque is transmitted by sliding of each rotary plate 21, 23 on the drive side, if the viscous fluid coupling on the torque transmission side continues to operate for a long time, overtorque will occur and the temperature of the viscous fluid will rapidly rise. The internal pressure increases. As a result, since the grooves 9a and 11a are provided on the opposing surfaces of the first and second power take-off sleeves 9 and 11, the viscous fluid is absorbed into the first and second sleeves 9 and 11.
1 and moves the sleeves 9 and 11 in the thrust direction, and the rotary plates 21 and 23 are pressed by the pressing plates 29 and 29, and the clutch parts K and K come to work as wet clutches, and the sleeves 9 and 11 are moved in the thrust direction. 1 and the second power take-off sleeves 9 and 11 are locked. This provides direct torque transmission. Therefore, the rise in temperature and internal pressure of the viscous fluid is suppressed, the viscous fluid and the sealing member are prevented from deteriorating, and the sealing member 19 is not damaged.

Note that the pressing plates 29, 29 provided in the viscous fluid couplings 15, 17 are connected to each rotating plate 2.
In this embodiment, all of the clutch parts 1 and 23 function as the clutch parts K, but it is also possible to use a part of them as the clutch parts K, as shown in FIG. That is, torque transmission is given by T=n・μ・γ・F.

n: Number of rotating plates μ: Friction coefficient γ: Average effective radius F: Thrust force Therefore, from the above formula, the pressing plates 29, 2
9 is provided in the middle of each rotary plate 21, 23, and the rotary plate 2
An experiment was conducted using parts of Nos. 1 and 23 as clutch parts K and K, and sufficient torque was obtained. In this case, a spacer 33 is interposed between the rotating plates 21 and 23 other than the clutch portion K to ensure a predetermined gap.

Further, the power transmission device can be provided in the middle of the transmission system between the front wheels and the rear wheels in a four-wheel drive type vehicle.

[Effects of the invention] As explained above, according to the actuation drive mechanism of this invention, the viscous fluid couplings are provided symmetrically, and the couplings are connected to the case by the movement of the first and second power take-off sleeves when the internal pressure increases. Since it functions as a clutch that locks each sleeve, the structure is simple and it can be housed within the case, making it more compact.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the differential drive mechanism of this invention, and FIG. 2 is a sectional view similar to FIG. 1 showing a modified example of the viscous fluid coupling. Explanation of main drawing symbols, 1... Case, 9, 1
1...First and second power take-off sleeves, 15, 17
...Viscous fluid coupling, W...Common axis, K
...Clutch club.

Claims (1)

[Scope of utility model registration request] First and second power take-off sleeves are provided in a rotatable case, to which the rotational power of the case is transmitted via a viscous fluid coupling, and whose rotation center is about a common axis, the first and second power take-off sleeves. is provided with groove means for conducting viscous fluid between the sleeves so as to move in the axial direction against the biasing springs provided between the case and the sleeves when the internal pressure of the viscous fluid coupling increases; A power transmission device characterized in that a clutch portion is provided in at least a portion of the viscous fluid coupling for fastening the sleeves by movement by the groove means.