JPH0543298Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Industrial application field) This invention absorbs the difference in rotation speed between the front wheel drive shaft and the rear wheel drive shaft in a four-wheel drive vehicle, and also uses this difference in rotation speed to generate driving force. This invention relates to a power transmission device using a viscous cut spring that produces

(Prior art) In the case of a four-wheel drive vehicle that transmits the driving force from the engine to the front wheel drive shaft and the rear wheel drive shaft, when the four-wheel drive vehicle is parked in a garage or when turning a so-called tight corner, the front wheel drive shaft is A difference in rotational speed occurs between the rear wheel drive shaft and the steering wheel, which increases steering force or causes the engine to stall. For this reason, a viscous cut spring is used as a power transmission device to absorb this rotational speed difference when turning a tight corner, and to generate driving force from this rotational speed difference when driving on a rough road. It is placed on the road.

As such a conventional viscous cut spring, there is one used, for example, in a center differential device as shown in FIG. 4 (see Japanese Patent Laid-Open No. 52-22231).

In the figure, reference numeral 1 denotes a first shaft connected to a rear-wheel drive shaft (not shown), and reference numeral 2 denotes a second shaft connected to a front-wheel drive shaft (not shown). The first shaft 1 engages with an outer cylinder 3, and the second shaft 2 engages with an inner cylinder 4. Both ends of the outer cylinder 3 and the inner cylinder 4 are defined by end plates 5, 6 and further sealed to form a sealed container 7, in which a viscous fluid is sealed. The inner cylinder 4 can move left and right as a differential piston, and the inner cylinder 4 can move left and right as a differential piston.
An operating plate 8 is fixed to the end plate 5. The inside of the sealed container 7 is divided into a first chamber 9 and a second chamber 10 by this operating plate 8. The first chamber 9 and the second chamber 10 contain a first rotating plate 11 and a third rotating plate 12 which are spline-fitted with the outer cylinder 3, and a second rotating plate 13 and a fourth rotating plate 14 which are spline-fitted with the inner cylinder 4. A disc spring 15 is interposed between the inner cylinder 4 and the end plate 5, and the biasing force of this disc spring 15 biases the inner cylinder 4 to the left.

When a vehicle drives straight on a paved road,
The driving force from the engine is equally distributed and transmitted to the rear wheel drive shaft and the front wheel drive shaft. However, when a vehicle travels on a rough road filled with rainwater, for example, if the front wheels slip, a difference in rotational speed occurs between the front wheel drive shaft and the rear wheel drive shaft. For this reason, the first axis 1
A difference in rotational speed occurs between the rotational speed and the second shaft, and the first rotary plate 11 and the third rotary plate 12 are spline-fitted with the outer cylinder 3, and the second rotary plate 13 and the third rotary plate are spline-fitted with the inner cylinder 4. The viscous fluid is sheared by the four-rotation plate 14, and the shearing force of the viscous fluid generated at this time is transmitted to the rear wheel drive shaft as a driving force, allowing the vehicle to travel by the rear wheels.

By the way, when the viscous fluid in the closed container 7 is sheared, heat is generated in the viscous fluid due to this shearing. Due to this heat, the viscous fluid expands against the sealed container 7, and a pressure of the viscous fluid that exceeds atmospheric pressure is generated in the container 7. When the pressure of the viscous fluid increases, the inner cylinder 4 serving as a differential piston exceeds the set load of the disc spring 15, and the disc spring 15 bends while the inner cylinder 4 moves to the right. When the inner cylinder 4 moves to the right, the actuating plate 8 is also pushed to the right, and the actuating plate 8 causes the third rotary plate 12 and the fourth
The rotating plate 14 is pressed to connect the clutch. By this clutch connection, the outer cylinder 3 and the inner cylinder 4 rotate together, and the heat of the viscous fluid in the closed container 7 decreases, that is, the pressure of the viscous fluid decreases. Therefore, problems such as damage to the sealing member that seals the closed container 7 and damage to the closed container 7, which would otherwise occur due to an increase in the pressure of the viscous fluid, are prevented.

After a while, the pressure of the viscous fluid in the closed container 7 also decreases, and the biasing force of the disc spring 15 overcomes the pressing force of the inner cylinder 4, causing the inner cylinder 4 to move to the right and the third rotary plate 12 and the fourth The rotating plate 14 is no longer frictionally connected.

(Problems to be Solved by the Invention) However, in the case of such a viscous coupling spring, the disc spring 15 used in this device exhibits characteristics as shown in FIG. In the same figure, part A of the characteristics of the disc spring 15 shows that the disc spring 1
It would be ideal to set a load at which 5 begins to deflect, but in reality, there are times when a load at which deflection begins is set at part B of this characteristic.

For example, if the load at which portion B begins to deflect is f ₁ Kg/cm ² , when the pressure of the viscous fluid reaches this load, the third rotary plate 12 and the fourth rotary plate 14 begin to be clutched together. However, this disc spring 15
While the clutch is deflected and displaced by Δδ, the load that causes it to deflect is also f ₂ Kg/cm ² , which is correspondingly higher, and unless the pressure of the viscous fluid reaches that load, the clutch will not continue to connect. It turns out. Therefore, even if the pressure of the viscous fluid reaches the load at which the disc spring 15 starts to deflect (for example, f ₁ Kg/cm ² ), the third rotary plate 12 and the fourth rotary plate 14 immediately respond and fasten. Not done. Therefore, even if the pressure of the viscous fluid exceeds a predetermined pressure, the outer cylinder 3 and the inner cylinder 4 do not immediately rotate together, and the decrease in the pressure of the viscous fluid tends to be slow. As a result, there was a fear that the conventional problems in the closed container 7 due to the increase in the pressure of the viscous fluid would remain unsolved.

(Means for Solving the Problems) In order to solve such problems, this invention provides a first rotating member and a second rotating member that are relatively rotatable, and a first rotating member and a second rotating member that are relatively rotatable. It is interposed between the two rotating members to partition the friction clutch chamber and the viscous clutch chamber, and moves toward the friction clutch chamber when the pressure of the viscous fluid sealed in the viscous clutch chamber rises above a predetermined pressure. an actuating member for clutching a clutch plate housed in a lever chamber; a locking pin that is attached to the actuating member so as to be able to protrude and retract in a radial direction and has rounded ends; The actuating member can move in sliding contact with a groove having a V-shaped cross section formed on the wall surface of one of the rotary members with which the actuating member is in sliding contact, and within a hole whose outer peripheral surface intersects with the pin storage hole of the actuating member. a piston mounted so that its end face receives the pressure of the viscous fluid in the viscous clutch chamber; and a piston formed on the outer circumferential surface of the piston so that the other end of the lock pin fits into it when the piston moves. The movement of the actuating member is locked until the pressure of the viscous fluid in the viscous clutch chamber rises to a predetermined pressure, and this locked state is released when the pressure of the viscous fluid in the viscous clutch chamber rises above the predetermined pressure. The actuating member moves in response to the pressure of the viscous fluid in the viscous clutch chamber to engage the clutch plate.

(Function) When a difference in rotational speed occurs between the first rotating plate and the second rotating plate, the viscous fluid sealed in the viscous clutch chamber is engaged with the first rotating body and the second rotating body alternately. Heat is generated in this viscous fluid as it is sheared by the resistance plate. The viscous fluid expands due to this heat, and as a result, the pressure of the viscous fluid increases to a predetermined pressure, and the locking state of the operating member by the locking mechanism is released by the unlocking portion. As a result, when the pressure of the viscous fluid in the viscous clutch chamber increases above a predetermined pressure, the clutch plate can be engaged in response to this pressure via the actuating member. Therefore, the first rotating member and the second rotating member rotate together, and the viscous fluid is no longer sheared by the resistance plate. Therefore, even if the pressure of the viscous fluid in the viscous clutch chamber becomes higher than a predetermined pressure, this pressure can be lowered at a constant pressure.

(Example) This invention will be explained below based on the drawings. 1 to 3 are diagrams showing an embodiment of the power transmission device according to this invention.

This power transmission device is incorporated into a transfer that distributes and transmits the driving force of the engine to the front wheel drive shaft and the rear wheel drive shaft.

First, the configuration will be explained. In Figure 1, 21
22 is a first rotating member connected to a front wheel drive shaft (not shown), and 22 is a second rotating member connected to a rear wheel drive shaft (not shown).
The driving force from the engine is distributed and transmitted between the rotary member 1 and the second rotating member 22 .

This first rotating member 21 has a substantially cylindrical shaft 23,
A left side wall member 24 spline-fitted to the end of this shaft 23, an intermediate cylindrical member 25 fixed to the peripheral edge of this left side wall member 24, and this intermediate cylindrical member 25.
It consists of a driving cylindrical member 26 that is fixed to the engine and to which driving force from the engine is transmitted, and a right side wall member 27 that is fixed to the driving cylindrical member 26. Therefore, the driving force from the engine first goes to ring gear 1.
8 to the driving cylindrical member 26, and is transmitted to the first shaft 23 via the intermediate cylindrical member 25 and the left side wall member 24.
The power is further transmitted to the front wheel drive shaft. 1st axis 2
A substantially cylindrical shaft serving as the second rotating member 22 is fitted to the outer periphery of the rotating member 3 so as to be coaxial and relatively rotatable.

A chamber is defined between the first rotating member 21 and the second rotating member 22, and this chamber is formed by a substantially cylindrical member interposed between the tip end of the second rotating member 22 and the intermediate cylindrical member 25. Friction clutch chamber 29 by actuating member 28
and a viscous clutch chamber 30. The friction clutch chamber 29 includes a first clutch plate 31 spline-fitted to the inner wall surface of the intermediate cylindrical member 25, and a second clutch plate 31.
A second clutch plate 32 that is spline-fitted to the outer peripheral side surface of the tip of the rotating member 22 is housed therein.
The viscous clutch chamber 30 houses a first rotary plate 33 spline-fitted to the inner wall of the drive cylindrical member 26 and a second rotary plate 34 spline-fitted to the outer peripheral wall of the second rotary member 22. Actuation member 28
and the intermediate cylindrical member 25, and the actuating member 28.
Seal members 35 and 36 are interposed between the right side wall member 2 and the second rotating member 22, respectively.
A seal member 37 is also provided between 7 and the second rotating member 22.
is interposed. The viscous clutch chamber 30 is filled with extremely viscous silicone oil as a viscous fluid.

As shown in FIG. 2, the actuating member 28 has a piston housing hole 38 formed in the axial direction, and this piston housing hole 38 is connected to a large diameter hole 38a and a small diameter hole 38.
It has b. A piston 39 is slidably housed in the piston housing hole 38 .
9 has a large diameter portion 39a and a small diameter portion 39b, the large diameter portion 39a is accommodated in the large diameter hole 38a, and the small diameter portion 39b is accommodated in the small diameter hole 38b. A step portion 38c is formed on the opposite side of the small diameter hole portion 38b from the large diameter hole portion, and a compression spring 46 is interposed between the step portion 38c and the piston 39. Also, large diameter part 3
A sealing member 40 is provided between 9a and the large diameter hole 38a.
is interposed. Small diameter hole 38 of actuating member 28
A pin storage hole 41 is bored in a radial direction from b toward the outer peripheral wall surface, and a substantially cylindrical lock pin 42 is stored in this pin storage hole 41, and both ends of this lock pin 42 are formed to have a rounded shape. ing.

On the other hand, a lock recess 43 is formed on the inner circumferential wall surface of the intermediate member 25 so that the upper end of the lock pin 42 fits therein.
The lock recess 43 has a substantially V-shaped groove in cross section, and is deepest at the center and becomes shallower toward the periphery, with a slope 43a formed from the center to the periphery. . Further, a release recess 44 is formed in the peripheral side wall of the small diameter portion 39b of the piston 39 as a lock release portion so that the lower end portion of the lock pin 42 is fitted therein.

The lock recess 43, the lock pin 42, and the piston 38 collectively constitute a lock mechanism 45, and when the lock pin 42 is fitted into the center of the lock recess 43 and this fitted state is maintained by the peripheral side wall of the piston 39, Movement of the actuating member 28 is locked.

Next, the action will be explained.

When a vehicle drives straight on a paved road,
The driving force from the engine is transmitted from the left side wall member 24 to the first shaft 23 via a spline to one of the front wheel drive shafts.
Since the driving force is directly input to the rear wheel drive shaft and transmitted through the viscous clutch chamber, the power transmission ratio between the front and rear wheels is distributed and transmitted at a ratio of, for example, 5:1 to 9:1. , which runs on the front wheels.

Next, when the vehicle is driving on a rough road, for example, if the front wheels fall onto a road surface with a low coefficient of friction such as a place where rainwater collects, or a ditch, etc., the front wheels may slip.
A difference in rotational speed occurs between the front wheel drive shaft and the rear wheel drive shaft. That is, the first rotating member 21 connected to the front wheel drive shaft is directly rotated by the engine, but because the resistance on the wheel side is reduced, only a small driving force is exerted. In addition, the second rotating member 22 connected to the rear wheel drive shaft rotates at a lower speed than the engine side rotation speed (front wheel drive shaft), so the second rotating member 22 connects to the rear wheel drive shaft.
Due to the difference in rotational speed between the rotating member 21 and the second rotating member 22, the first rotating plate 33 rotates simultaneously with the first rotating member 21 and the second rotating plate rotates simultaneously with the second rotating member 22. 34 resists the viscous resistance of the silicone oil, shears the silicone oil, and begins relative rotation. The shearing force of the silicone oil generated at this time is transmitted as driving force to the rear wheel drive shaft, and the rear wheels push the vehicle out, causing the front wheels to escape from the slip state. On the other hand, when the silicone oil within the viscous clutch chamber 30 is sheared in this manner, heat is generated in the silicone oil within the viscous clutch chamber 30 due to this shearing.
This heat causes the silicone oil to expand, creating a silicone oil pressure within the viscous clutch chamber 30. At this time, the lock pin 42 is kept fitted into the lock recess 43 of the intermediate cylindrical member 25 by the outer peripheral wall of the small diameter portion 39b of the piston 39 until the pressure of the silicone oil reaches a predetermined pressure. That is, the lock mechanism 45 is activated and movement of the operating member 28 toward the friction clutch chamber 29 is restricted. When the pressure of the silicone oil increases, the piston 39 is pushed and moved toward the friction clutch chamber 29 against the biasing force of the compression spring 46. When the pressure of the silicone oil reaches a predetermined pressure, the piston 39 moves toward the friction clutch chamber 29, and the release recess 44 is located at the lower end of the lock pin 42, so that the lock pin 42 can be inserted into the release recess 44. Become. When the lock pin 42 fits into the release recess 44, the locking state of the actuating member 28 is released. Therefore, the actuating member 28 is pressed and moved toward the friction clutch chamber 29 by the pressure of the silicone oil that exceeds a predetermined pressure.

Therefore, when the pressure of the silicone oil exceeds a predetermined pressure, the actuating member 28 immediately responds to this pressure without receiving the reaction force of a disc spring or the like as in the conventional case, and operates the first clutch in the friction clutch chamber 29. Board 31
The first clutch plate 31 and the second clutch plate 32 are connected by pressing the second clutch plate 32 to connect the first clutch plate 31 and the second clutch plate 32.

When the first clutch plate 31 and the second clutch plate 32 are fastened together, the first rotating member 21 and the second rotating member 2
It rotates together with 2. As the first rotating member 21 and the second rotating member 22 rotate together, the first rotating plate 33 housed in the viscous clutch chamber 30
The second rotating plate 34 also rotates together, and the silicone oil is no longer sheared by the first rotating plate 33 and the second rotating plate 34. Therefore, the heat generated in the viscous clutch chamber 30 is rapidly reduced, and thus the pressure of the silicone oil is rapidly reduced.

In this way, when the pressure of the silicone oil in the viscous clutch chamber 30 rises above a predetermined pressure, the first clutch plate 31 and the second clutch plate 32 are immediately engaged in response to this pressure, and the first rotating member 2
1 and the second rotating member 22 rotate together, the pressure of the silicone oil decreases rapidly. Therefore, even if the pressure of silicone oil becomes higher than a predetermined pressure, this pressure can be immediately lowered, thereby preventing damage to the sealing members 35, 36, and 37 that seal the viscous clutch chamber 30, and even preventing the viscous clutch chamber 30 from being damaged. First rotating member 21 defining clutch chamber 30
Also, problems such as damage to the second rotating member 22 are prevented from occurring.

On the other hand, the upper end of the lock pin 42 rides on a slope 43a from the deepest part of the recess 43, and the reaction force of the slope 43a constantly urges the actuating member 28 toward the viscous clutch 30 (returns) via the lock pin 42. ) has been done. Therefore, slope 4
3a and the lock pin 42 constitute a return mechanism for returning the actuating member 28. In response to the reduced silicone oil pressure, the action of the return mechanism and the biasing force of the compression spring 46 push the actuating member 28 into the viscous clutch chamber 30 as shown in FIG. When the actuating member 28 moves toward the viscous clutch chamber 30, the lock pin 42 also moves toward the viscous clutch chamber 30, and the upper end of the lock pin 42 fits into the deepest part of the lock recess 43. When the upper end of the lock pin 42 is inserted into the deepest part of the lock recess 43, the lower end of the lock pin 42 is inserted into the release recess 4.
4, and the lock pin 42 is kept in the lock recess 43 by the outer circumferential wall of the piston 39 pushed by the biasing force of the compression spring 46. Therefore, the actuating member 28 is again locked by the locking mechanism 45 until the pressure of the silicone oil in the viscous clutch chamber 30 reaches a predetermined pressure.

In the present invention, a viscous coupling spring with a center differential function for a four-wheel drive vehicle has been described, but it may also be used in an actuating device used between front axle shafts or rear axle shafts.

(Effects of the invention) As explained above, this invention has a lock mechanism that locks the movement of the actuating member until the pressure of the viscous fluid in the viscous clutch chamber rises to a predetermined pressure, and a lock mechanism that locks the movement of the actuating member until the pressure of the viscous fluid in the viscous clutch chamber increases A lock release part is provided which releases the locked state by this locking mechanism when the viscous clutch rises above a predetermined pressure, and when this locked state is released, it immediately responds to the pressure of the viscous fluid in the viscous clutch chamber via the actuating member. Since the clutch plate housed in the friction clutch chamber is connected in a clutch manner, even if the pressure of the viscous fluid becomes higher than a predetermined pressure, the pressure in the viscous clutch chamber can be immediately reduced. Therefore, it is possible to prevent problems such as damage to the sealing member that seals the viscous clutch chamber, and further damage to the first and second rotating members that define the viscous clutch chamber.

[Brief explanation of the drawing]

1 to 3 are diagrams showing an embodiment of the viscous coupling device according to this invention. FIG. 1 is a cross-sectional view showing the entire device, and FIG. FIG. 3 is an enlarged sectional view showing the device shown in FIG. 2 in a state where the locking mechanism is released. FIG. 4 and FIG. 5 are diagrams showing a conventional viscous coupling device,
Figure 4 is a cross-sectional view showing the entire device;
The figure is a graph showing the characteristics of the disc spring used in this device. 21...first rotating member, 22...second rotating member, 28...operating member, 29...friction clutch chamber, 30...viscous clutch chamber, 44...lock release section, 45...lock mechanism.

Claims (1)

[Scope of utility model registration request] A first rotating member and a second rotating member that are relatively rotatable; and a first rotating member and a second rotating member that are interposed between the first rotating member and the second rotating member to partition a friction clutch chamber and a viscous clutch chamber; When the pressure of the enclosed viscous fluid rises to a predetermined pressure or higher, an actuating member moves toward the friction clutch chamber and connects the clutch plates housed in this chamber, and an actuating member that can freely move in and out of the actuating member in a radial direction. a lock pin which is attached and has rounded ends; and a groove having a V-shaped cross section formed on the wall surface of one of the rotary members in which the operating member slides into contact with the lock pin so that one end of the lock pin is fitted into the lock pin. , a piston mounted so that its outer peripheral surface can move in sliding contact within a hole intersecting with the pin storage hole of the actuating member, and so that its end surface receives the pressure of the viscous fluid in the viscous clutch chamber; a recess formed on the outer circumferential surface of the piston so that the other end of the lock pin fits into the piston when the actuating member moves, and locks the movement of the actuating member until the pressure of the viscous fluid in the viscous clutch chamber rises to a predetermined pressure. However, when the pressure of the viscous fluid in the viscous clutch chamber rises above a predetermined pressure, this locked state is released, and the actuating member moves in response to the pressure of the viscous fluid in the viscous clutch chamber to connect the clutch plates. A power transmission device characterized by: