JP2818635B2 - Hydraulic power transmission coupling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic power transmission coupling used for distributing driving force of a vehicle.

[0002]

2. Description of the Related Art As a conventional hydraulic power transmission coupling, there is, for example, one disclosed in Japanese Utility Model Application No. 2-74479. That is, this hydraulic power transmission coupling
A hydraulic pump driven by a rotational speed difference between the first and second rotating members that can rotate relative to each other, and a unit that generates a flow resistance in a discharge path of the hydraulic pump; 2. A hydraulic power transmission coupling in which the transmission torque between two rotating members is controlled, comprising: an accumulator piston for absorbing a change in volume of a sealed oil enclosed in the coupling; and a retainer holding a return spring for pressing the accumulator piston. In the hydraulic power transmission coupling comprising: and a room defined by the accumulator piston and the retainer, and a communication hole that communicates with the outside of the joint,
The retainer is provided at least at a position outside the outer diameter of the accumulator piston.

Further, as a conventional hydraulic power transmission coupling, there is one disclosed in Japanese Utility Model Application No. 2-74480, for example. That is, the hydraulic power transmission coupling includes a hydraulic pump driven by a rotational speed difference between the first and second rotatable members that can rotate relative to each other, and a unit that generates a flow resistance in a discharge path of the hydraulic pump. A hydraulic power transmission joint in which a transmission torque between the first and second rotating members is controlled by the flow resistance, wherein an accumulator piston for absorbing a volume change of a sealed oil sealed in the joint; and the accumulator A hydraulic power transmission coupling including a retainer for holding a return spring that presses a piston, wherein the retainer is liquid-tightly fixed to a joint outer cylinder portion, and an oil sump chamber into which lubricating oil flows from outside the joint is provided. It is provided between an accumulator piston and the retainer.

[0004]

However, in such a conventional hydraulic power transmission coupling, in the latter case, there is only a slight clearance between the retainer and the coupling, so that there is no foreign matter such as dust. Was accumulated on the accumulator piston by centrifugal force during rotation, and there was a danger of oil leakage due to wear and damage of the O-ring.

Further, when the temperature of the joint rises due to the operation and the oil expands, the accumulator piston moves outward, and the oil accumulated between the retainer and the accumulator piston is pushed, and a hole or shaft holding the return spring is stopped. When the oil is discharged from the hole near the heart and then stops operating, the oil cools down, the accumulator piston moves inward, and the oil between the return spring and the accumulator piston decreases. If the absolute rotation of the joint rises in this state, the amount of oil inside and outside the accumulator piston becomes unbalanced, and the oil pressure inside the unit cannot be maintained.

On the other hand, as a problem common to both, since the structure is weak against dust and muddy water, the hydraulic power transmission coupling cannot be an external type as between the gear box and the propeller shaft. There is a problem. Further, as a problem common to both, there is also a problem that the oil seal slides on the rotor and a large preload is applied to the oil seal via a return spring, so that durability is low.

Further, as a problem common to both, there is a problem that a return spring, a retainer and the like are required, the structure is not simple, the number of parts is large, and the weight is not light. The present invention has been made in view of such a conventional problem, and prevents an intrusion of foreign matter such as dust, holds the hydraulic pressure inside the unit up to a high-speed rotation range, and provides an external type. An object of the present invention is to improve the durability of the oil seal, and to reduce the weight of the oil seal with a simple structure and a small number of parts.

[0008]

In order to achieve the above object, the present invention provides a hydraulic pump driven by a rotational speed difference between first and second rotating members which can rotate relative to each other, and a hydraulic pump driven by the hydraulic pump. A hydraulic power transmission coupling, comprising: means for generating flow resistance in a discharge path, wherein transmission torque between the first and second rotating members is controlled by the flow resistance. In a hydraulic power transmission coupling including an accumulator piston for absorbing a volume change, a chamber in which air and oil are sealed by a cover is provided on a back surface of the accumulator piston.

[0009] The present invention also provides a first rotatable relative rotatable motor.
Hydraulic pump driven by rotation speed difference between two rotating members
And a means for generating flow resistance in the discharge path of the hydraulic pump.
A step, and the first and second rotating parts are provided by the flow resistance.
Hydraulic power transmission joint in which the transmission torque between members is controlled.
Absorbs the volume change of the oil enclosed inside the joint
Hydraulic power transmission coupling with accumulator piston
At the back of the accumulator piston, a cover
To provide a chamber that seals only air at a predetermined pressure
It is characterized by. Further, the present invention is characterized in that a spring having a predetermined tension is interposed in the room. Further, the present invention is characterized in that an oil seal is interposed between the cover and one of the first and second rotating members.

Further, the present invention is characterized in that one end of the cover is fixed to one outer diameter of the first and second rotating members. Further, the invention is characterized in that one end of the cover is fixed to one of the inner diameters of the first and second rotating members.

[0011]

According to the hydraulic power transmission joint of the present invention having the above-described structure, a chamber in which air and oil are sealed by a cover is provided on the back surface of the accumulator piston. When the oil in the joint thermally expands, the accumulator piston moves outward, the oil in the room is pushed and the liquid level rises, and it tries to push the accumulator piston outward. Force becomes smaller, while
The pressure of the air in the room is increased due to the reduced volume, and as a result, the volume change due to the thermal expansion of the oil is absorbed.

In the present invention, since the amount of oil inside and outside the accumulator piston does not become unbalanced as in the prior art, the oil pressure inside the joint can be maintained up to the high-speed rotation range. In addition, foreign substances such as dust can be prevented from entering, and damage to the O-ring and the like can be prevented, so that oil leakage can be prevented beforehand.

Further, since the structure can be made strong against dust and muddy water, the joint can be of an external type such as between the gear box and the propeller shaft. In addition, since an oil seal is provided between the cover and one of the first and second rotating members, the oil seal does not slide due to the movement of the accumulator piston and does not receive a large preload. Performance can be improved.

Further, since a return spring can be omitted, the number of parts can be reduced.
The structure is simple and lightweight.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 are views showing an embodiment of the present invention.
First, the configuration will be described. In FIGS. 1 to 3, reference numeral 1 denotes, for example, a case of a final drive unit. One end of an output shaft 3 is rotatably supported on the case 1 via a bearing 2. The output shaft 3 has a male spline portion 4 and a screw portion 5.

Reference numeral 6 denotes a rotor shaft (first rotating member) of a joint 7 connected to the output shaft 3. The rotor shaft 6 has a hollow portion 8 formed therein. A step 9 is formed in the hollow section 8, and a female spline section 11 that fits into the spline section 4 of the output shaft 3 is formed in the small diameter section 10 on the right side of the step section 9. Rotor shaft 6 and output shaft 3
Are spline-fitted by the spline portions 11 and 4, the washer 12 is inserted into the screw portion 5 until it comes into contact with the step portion 9, and is fastened by the nut 13.

The cylindrical surface of the outer diameter portion 14 of the rotor shaft 6 is precision-finished, and an oil seal 15 is interposed between the outer diameter portion 14 and the case 1. Reference numeral 16 denotes a housing connected to an input shaft (not shown) by bolts 17, and the housing 16 constitutes a second rotating member. An X ring 18 is interposed between the housing 16 and the rotor shaft 6, and the X ring 18 prevents oil leakage.

A cam surface 19 is formed on the inner diameter of the housing 16. A plurality of plunger chambers 20 are formed in the rotor shaft 6 in the radial direction, and a plurality of plungers 21 are slidably accommodated in the plunger chamber 20 via a return spring 22. The plunger 21 has a suction / discharge hole 23 formed therein.
1 and the check valve 2
The check valve 24 is provided by a retainer 26 via a spring 25.

As shown in FIG. 4, an orifice 27 is formed in the check valve 24 as flow resistance generating means, and the suction / discharge port 23 and the plunger chamber 20 communicate with each other through the orifice 27. The check valve 24 is held by a retainer 26 via a spring 25, and the retainer 26 is held by a return spring 22.

As shown in FIG. 5, the retainer 26 has an opening 2 for communicating the plunger chamber 20 with the orifice 27.
8 are provided, and a plurality of notches 29 are formed in the circumferential direction. In FIG. 1, reference numeral 30 denotes a snap ring inserted into the inner diameter of the housing 16, and the snap ring 30 prevents the rotor shaft 6 from coming off the housing 16.

Reference numeral 31 denotes a side cover (cover). One end of the side cover 31 is fixed to a groove 32 formed in the housing 16. The side cover 31 has an air chamber (chamber) in which air and oil are sealed behind the accumulator piston 33.
34 are formed. Air and oil are sealed in the air chamber 34 with a certain preload. The accumulator piston 33 stops at a position where the centrifugal force of the oil annular portion between the inner diameter of the oil stuck to the outer diameter portion by rotation and the minimum diameter portion of the joint containing oil and the pushed air balance. Thereafter, when the oil inside the joint thermally expands, the accumulator piston 33 moves rightward in FIG. 1 to absorb a change in the volume of the oil.

O-rings 35 and 36 are interposed between the side cover 31 and the accumulator piston 33, and the O-rings 35 and 36 prevent oil leakage. An oil seal 37 is interposed between the inner diameter of the side cover 31 and the outer diameter of the rotor shaft 6. The oil seal 37 does not slide regardless of the operation of the accumulator piston 33, and no preload is applied. In addition, 3
Reference numeral 8 denotes an O-ring interposed between the side cover 31 and the housing 16.

Next, the operation will be described. When a rotation difference occurs between the housing 16 and the rotor shaft 6, the plunger 21 in the discharge stroke causes the cam surface 1 of the housing 16 to rotate.
9 pushes radially. Plunger room 20
Is supplied to the low-pressure chamber from the suction / discharge hole 23 through the orifice 27. At this time, the hydraulic pressure in the plunger chamber 20 increases due to the resistance of the orifice 27, and a reaction force is generated in the plunger 21. By rotating the housing 16 against this plunger reaction force, a torque is generated, and the torque is transmitted between the housing 16 and the rotor shaft 6.

That is, torque proportional to the square of the relative rotation between the rotor shaft 6 and the housing 16 is transmitted. Here, as shown in the upper half of FIG. 1, the accumulator piston 33 stops at a position where the centrifugal force acting by the rotation of the joint and the pushed air are balanced. Thereafter, when the oil inside the joint thermally expands, the accumulator piston 33 moves rightward as shown in the lower half of FIG. 1, and the oil in the air chamber 34 is pushed by the accumulator piston 33, and the liquid level is raised. climb. That is, the liquid level decreases from Lo to L. For this reason, the force for pushing the accumulator piston 33 outward is reduced, while the volume of the air in the air chamber 34 is reduced, and the pressure is increased. Thus, the accumulator piston 33
Absorbs changes in oil volume due to thermal expansion inside the joint.

Next, FIG. 6 shows the absolute rotational speed of the joint and the force due to the centrifugal force of the oil generated in the accumulator piston 33.
The relationship with the air pressure generated in the air chamber is shown. In FIG. 6, (A) shows the force for moving the accumulator piston 33 due to the centrifugal force of the oil when the back surface of the accumulator piston 33 is the atmosphere, and (B) shows the case where the initial oil is on the back surface of the accumulator piston 33. The force that tries to move the accumulator piston 33 due to the centrifugal force of the oil
(C), the oil in the joint is thermally expanded and the accumulator piston 33 moves due to the temperature rise, the oil level on the back of the accumulator piston rises, and the force due to the centrifugal force of the oil generated in the accumulator piston 33 is reduced. Indicates the status.

That is, the force due to the centrifugal force of the oil generated in the accumulator piston 33 is smaller when the initial oil is on the back surface than when the back surface is atmospheric, and the accumulator piston 33 is moved by the thermal expansion of the oil. The initial oil is smaller than when it is on the back. On the other hand, (D) shows the force due to the pressure on the back side due to air confinement during initial assembly, and (E) and (F) show the pressure rise due to the movement of the accumulator piston 33 due to the temperature rise and the pressure rise due to the thermal expansion of the air itself. Are respectively shown.

That is, the air pressure generated in the air chamber 34 is caused by the movement of the accumulator piston 33 and
It becomes larger due to the thermal expansion of the air itself. Next, the relationship between the stroke of the accumulator piston 33, the centrifugal force, and the air pressure is shown in FIG. In FIG. 7, (f) shows the air pressure in the air chamber 34 on the back of the accumulator piston 33. The air pressure increases as the stroke of the accumulator piston 33 increases, and as shown in FIG. The higher the value, the larger.

(H) shows the centrifugal force generated in the accumulator piston 33, and the centrifugal force decreases as the stroke of the accumulator piston 33 increases. On the other hand, as shown in (i), the centrifugal force increases as the rotational speed increases. Become. (E) shows a limit at which the joint cannot operate normally due to the generation of a cavity.

FIG. 3A shows a state in which the number of rotations is low and the oil temperature is also low.
3 balances the left and right forces. The point (b) shows the state of balance when the number of rotations is high and the expansion of the oil increases. The point (c1) indicates a state where the oil expansion is further increased, and the air pressure of the accumulator piston 33 is (c2)
This indicates that the preload of (c2)-(c1) is generated in the accumulator piston 33.

As described above, when the line h indicating the centrifugal force is below the line f indicating the state of the air pressure, it indicates a state in which the preload is applied to the accumulator piston 33, and a cavity is formed inside the joint. It does not occur. On the other hand, if the temperature is extremely low and the condition shown in (d1) suddenly occurs such that the rotation shown in (d1) becomes the maximum rotation (d2), the accumulator piston 33 moves outward, and the inside of the joint becomes negative pressure, and ( It will move to the position of d3).

As described above, the accumulator piston 33
Moves, and a cavity is formed inside the joint. Since this cavity is located at the center of rotation, normal operation is performed within the movement range of (e) or less. Therefore, even if the accumulator piston 33 moves, the initial air pressure may be set low so that the balance point is within a range satisfying the joint function.

As described above, the accumulator piston 33
The air chamber 34 is provided by the side cover 31 on the back surface of the accumulator piston so that the air and the oil are sealed, so that the amount of oil inside and outside the accumulator piston does not become unbalanced as in the related art. The pressure of the oil inside can be maintained. Further, since the oil seal 37 is interposed between the side cover 31 and the rotor shaft 6, the oil seal 37 is attached to the accumulator piston 33.
Since no sliding occurs due to the movement and no large preload is applied, the durability can be improved.

In addition, foreign matter such as dust can be prevented from entering, and the O-ring is not damaged, so that oil leakage can be prevented. Further, since the structure can be made strong against dust and muddy water, the joint can be an external type such as between the gear box and the propeller shaft. Furthermore, the conventional return spring can be eliminated, the number of parts can be reduced, the structure is simple,
It can be lightweight.

FIG. 8 is a diagram showing another embodiment of the present invention. In FIG. 8, reference numeral 41 denotes a side cover, and one end of the side cover 41 is fixed to the inner diameter of the rotor shaft 6 and is prevented from falling off by a snap ring 42. An air chamber 43 in which air and oil are sealed by the side cover 41 is provided on the back surface of the accumulator piston 33. That is, air and oil are sealed in the air chamber 43 with a certain preload. The accumulator piston 33 absorbs a volume change due to thermal expansion of the oil by moving rightward in FIG.

Reference numeral 44 denotes a plate fixed to the inner diameter of the rotor shaft 6, and the plate 44 is prevented from coming off by a snap ring 45. By the plate 44,
The rotor shaft 6 is prevented from coming off the housing 16. In this embodiment, the rigidity of the housing 16 is improved by fixing the side cover 41 to the inner diameter of the rotor shaft 6. It is needless to say that the present embodiment can provide the same effect as the above embodiment.

In the present invention, the expansion of oil is absorbed by the closed air chambers 34 and 43, and the same effect can be expected even if there is no oil therein. Also,
A similar effect can be expected by providing a spring regardless of the presence or absence of oil in the air chambers 34 and 43. However, in such a case, it is necessary to assemble the initial preload at a high pressure that can be corrected at the maximum rotation even at a low temperature.

In this case, it is necessary to increase the size of the air chambers 34 and 43 so as to prevent an extremely large pressure from being generated when the oil expands and the air chambers 34 and 43 become small.

[0038]

As described above, according to the present invention, a chamber in which air and oil are sealed by a cover is provided on the back of the accumulator piston, and air pressure is applied to the accumulator piston. Intrusion can be prevented, and the coupling can be of an external type, such as between the gearbox and the propeller shaft.Also, the oil pressure inside the coupling can be maintained up to the high-speed rotation range. The durability of the seal can be improved, the structure is simple and the number of parts can be reduced,
It can be lightweight.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a side view of FIG. 1;

FIG. 4 is an enlarged view of a check valve.

FIG. 5 shows a retainer.

FIG. 6 is a graph showing the relationship between the rotation speed, centrifugal force, and air pressure.

FIG. 7 is a graph showing the relationship between the stroke of an accumulator piston, centrifugal force, and air pressure.

FIG. 8 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1: Case 2: Bearing 3: Output shaft 4: Spline section 5: Screw section 7: Joint 6: Rotor shaft 8: Hollow section 9: Step section 10: Small diameter section 11: Spline section 12: Washer 13: Nut 14: Outside Diameter part 15: Oil seal 16: Housing 17: Bolt 18: X ring 19: Cam surface 20: Plunger chamber 21: Plunger 22: Return spring 23: Suction / discharge hole 24: Check valve 25: Spring 26: Retainer 27: Orifice (flow resistance generating means) 28: Opening 29: Notch 30: Snap ring 31: Side cover (cover) 32: Groove 33: Accumulator piston 34: Air chamber (chamber) 35, 36: O-ring 37: Oil seal 38: O-ring 41: Side cover 42: Snap ring 43: Air chamber Room) 44: plate 45: snap ring

Claims (6)

(57) [Claims] 1. A hydraulic pump driven by a rotational speed difference between first and second rotating members rotatable relative to each other, and means for generating flow resistance in a discharge path of the hydraulic pump, wherein A hydraulic power transmission coupling, wherein a transmission torque between the first and second rotating members is controlled, wherein the hydraulic power transmission coupling includes an accumulator piston that absorbs a change in volume of oil sealed in the joint. A hydraulic power transmission coupling, wherein a chamber in which air and oil are sealed by a cover is provided on the back of the accumulator piston. 2. The method according to claim 1, wherein the first and second rotating members are rotatable relative to each other.
A hydraulic pump driven by the rotational speed difference; and means for generating flow resistance in a discharge path of the hydraulic pump.
For example, transmission between the first, second rotary member by the flow resistance
A hydraulic power transmission joint whose torque is controlled, which is an accumulator that absorbs changes in the volume of oil enclosed in the joint.
Hydraulic power transmission joint with murator piston
Te, a rear surface of the accumulator piston, where the cover
A hydraulic power transmission coupling characterized by having a chamber that seals only air at a constant pressure . 3. The hydraulic power transmission coupling according to claim 1, wherein a spring having a predetermined tension is interposed in the room. Wherein said and said cover first, according to claim 1 or 2 hydraulic power transmission joint, characterized in that interposed an oil seal between the one of the second rotary member. Wherein said first one end portion of the cover, according to claim 1 or 2 hydraulic power transmission joint, characterized in that fixed to one of the outer diameter portion of the second rotary member. Wherein said first one end portion of the cover, according to claim 1 or 2 hydraulic power transmission joint, characterized in that fixed to one inner diameter portion of the second rotary member.