JP2523370Y2 - Hydraulic power transmission coupling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulic power transmission coupling used for driving force distribution of a vehicle.

[Prior Art] In a hydraulic power transmission coupling using a plunger pump, oil is discharged by reciprocating motion of each plunger. Therefore, when air is mixed in hydraulic oil, the volume change of each cylinder causes air compression. Is absorbed by
Cannot function as a joint. Therefore, when lubricating the interior of the joint, it is necessary to completely bleed the air to fill the oil.

In order to prevent air mixing, there is a method such as assembling in oil.However, due to difficulties in assembling, conventionally two lubrication holes are provided in the center of the joint shaft end, and while differential is applied to the joint, The internal air was evacuated by pumping the oil from the other side and discharging the oil from the other side.

[Problem to be Solved by the Invention] In such a hydraulic power transmission joint, the lubrication hole needs to completely close the hole after lubrication and hermetically seal the joint itself. It is difficult to close the hole,
In addition, the lid was tapered with a lubricating jig. That is, the lubrication hole cannot be formed simply by making a hole on the outside of the joint. For example, when a hole is closed using a taper plug, a space for cutting the screw and inserting the plug is required. For this reason, if the lubrication hole is provided in the joint outer diameter,
The outer diameter of the joint increases. Further, if provided on the end face opposite to the cam, the setting of the accumulator and the like is restricted, and the axial length of the joint itself is increased by the length of the lubrication hole for the above-described reason. Increasing the size of the joints increases the weight of the vehicle on which the joints are mounted, which not only negatively impacts the kinematic performance of the vehicle, but also increases the cost of the joints. It is also possible that There is also a method of providing an oil hole in the shaft core.However, this does not hold when the diameter of the shaft itself is small, and even if the shaft diameter can be set, in order to allow the oil hole to communicate with the inside of the joint, the shaft must Drilling from at least two directions is required, which increases costs. Another conceivable part is the cam part that drives the plunger.If the cam is provided with a lubrication hole and the hole is opened in any place on the cam surface, the contact surface pressure between the cam and the plunger will decrease. As the torque capacity increases, the torque capacity decreases, and there is a problem that if the same torque capacity is secured, the joint itself also becomes large.

The present invention has been made in view of such a conventional problem, and has been made at a low cost and without lubrication and air bleeding without increasing the size of the joint and reducing the torque capacity. It is an object of the present invention to provide a power transmission coupling.

Means for Solving the Problems In order to achieve the above object, the present invention provides a cam having a plurality of cam lobes driven by a rotational speed difference between first and second rotatable members capable of relative rotation. A plunger pump for driving a plunger, and means for generating a flow resistance in a discharge path of the plunger pump, and a hydraulic pressure in which a torque between the first and second rotating members is controlled by the flow resistance. In the power transmission coupling, an oil hole is provided at a bottom of the cam.

[Operation] In the present invention, since the lubrication hole is provided so as to open at the bottom of the valley of the cam, without increasing the size of the joint,
Lubrication and air bleeding during lubrication can be easily performed without reducing the torque capacity.

If the contact surface pressure between the cam and the plunger exceeds the allowable limit, galling occurs at the contact part and the transmission torque capacity of the joint is determined.However, this contact surface pressure is highest at the top of the cam due to the cam shape. It is lowest at the bottom of the valley. Therefore, if a lubrication hole having a diameter such that it does not become higher than the contact surface pressure at the top of the cam ridge is opened at the bottom of the valley where the contact surface pressure is lowest, galling does not occur at the valley bottom. That is,
The torque capacity does not decrease.

Further, the thickness of the cam has a predetermined thickness in order to secure the strength of the cam and to couple the torque transmitting parts, and basically has a margin for providing the lubrication hole. Therefore, even if an oiling hole is provided in the cam, the joint does not become large.

Also, if the cam comes up when lubricating, the lubrication hole is located almost at the top of the oil chamber, so it is easy to bleed air when lubricating. There is no danger.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 3 show a first embodiment of the present invention.

First, the structure will be described. In FIGS. 1 and 2, reference numeral 1 denotes a cam having a cam surface 2 having two or more ridges on an inner surface, and a cam 1 is connected to an output shaft 3; 3 and rotate together. The cam 1 is a cam housing 4
, And the cam housing 4 rotates integrally with the cam 1.

Reference numeral 5 denotes a rotor rotatably housed in the cam housing 4. The rotor 5 is coupled to the input shaft 6 and rotates integrally with the input shaft 6.

A plurality of plunger chambers 7 are formed in the rotor 5 in the axial direction, and a plurality of plungers 8 are accommodated in the plunger chamber 7 slidably under the pressure of the return spring 9. Further, a plurality of suction / discharge holes 10 are formed in the rotor 5 so as to communicate with each plunger chamber 7.

11 is a suction port 12 and suction path 13 and discharge port on the surface
A rotary valve (valve element) 14 is formed. Each discharge port 14 of the rotary valve 11 has an orifice 17 as a flow resistance generating means. Further, the discharge ports 14 do not communicate with each other, and two or more plunger chambers 7 are not connected to one discharge port 14 at the same time. That is, the number of cam peaks is N
Then, the number of plunger chambers 7 is configured to be 2N-1 or less. In this embodiment, there are four cam peaks and seven plunger chambers 7.

The distance between the adjacent suction port 12 and discharge port 14 is smaller than the diameter of the suction and discharge hole 10 of the rotor 5. Therefore, the sealing phenomenon can be avoided without providing the sealing prevention notch.

The rotary valve 11 has a positioning projection 19 that engages with a notch 18 formed on the inner periphery of the cam housing 4.

The rotary valve 11 constitutes a timing member for determining the opening / closing timing of the suction / discharge hole 10, and includes a notch 18 and a projection 19.
Constitute a positioning mechanism that regulates the phase relationship between the cam 1 and the rotary valve 11.

When the plunger 8 is in the suction stroke, there is a positional relationship between the suction port 12 of the rotary valve 11 and the suction / discharge hole 10 of the rotor 5, and the plunger 8 passes through the suction passage 13, the suction port 12, and the suction / discharge hole 10 of the rotor 5. Oil can be sucked into the jar chamber 7.

When the plunger is in the discharge stroke, the relationship is opposite to that of the suction stroke, and the suction / discharge hole 10 of the rotor 5 communicates with the orifice 17 via the discharge port 14 of the rotary valve 11.

Reference numeral 20 denotes a thrust block which rotates integrally with the cam housing 4 and supports the input shaft 6 via a bearing 21. A needle bearing 22 is interposed between the thrust block 20 and the rotary valve 11, and the friction torque on the needle bearing 22 side is set to be smaller than the friction torque between the rotor 5 and the rotary valve 11. Therefore, when the direction of the differential rotation changes, the rotary valve 11 rotates together with the rotor 5, and rotates until the positioning projection 19 of the rotary valve 11 hits the notch 18 of the cam housing 4. Rotate with. Thus, the suction / discharge port 10 is forcibly opened and closed at a predetermined timing even in the normal rotation or the reverse rotation. 16 is a rolling wheel for a needle bearing.

Reference numeral 23 denotes an accumulator piston which rotates integrally with the cam housing 4, and the accumulator piston 23 moves according to the internal pressure. Accumulator piston 23 and retainer
A return spring 25 is interposed between the return spring 24.

Here, reference numeral 26 denotes two lubrication holes formed in each bottom of the cam 1, and the lubrication holes 26 open to the bottom pressure chamber inside the joint. A tapered screw hole 27 is formed continuously with the oil hole 26, and a tapered plug 28 is screwed into the tapered screw hole 27 (see FIG. 3).

When lubricating, lubricate from one of the lubrication holes 26
Oil is drained from the other side to bleed air. After lubrication,
The joint is sealed by screwing a taper plug 28 into the tapered screw hole 27.

29 is an oil seal, 30 is a stop ring, 31 is a bolt, and 32 is a bearing.

 Next, the operation will be described.

When there is no rotation difference between the cam 1 and the rotor 5,
The plunger 8 does not operate and no torque is transmitted. At this time, the plunger 8 is pressed against the cam surface 2 by the return spring 9.

Next, when a rotation difference occurs between the cam 1 and the rotor 5,
The plunger 8 in the discharge stroke is pushed in the axial direction by the cam surface 2 of the cam 1.

For this reason, the plunger 8 supplies the oil in the plunger chamber 7 from the suction / discharge port 10 to the discharge port 14 of the rotary valve 11.
Extrude.

The oil pushed out to the discharge port 14 is supplied to the orifice 17
Is supplied to the suction passage 13 through the air passage. At this time, orifice 17
, The hydraulic pressure in the discharge port 14 and the plunger chamber 7 rises, and a reaction force is generated in the plunger 8. By rotating the cam 1 against this plunger reaction force, a torque is generated, and the torque is transmitted between the cam 1 and the rotor 5.

Further, when the cam 1 rotates, a suction stroke occurs, and the suction / discharge port 10 communicates with the suction port 12, so that oil in the suction passage 13 is sucked into the plunger chamber 7 through the suction port 12 and the suction / discharge port 10, Plunger 8 is cam surface 2 of cam 1
Return along.

Here, if the contact surface pressure between the cam 1 and the plunger 8 exceeds the permissible limit, galling occurs at the contact portion, and as a result,
The torque capacity of the joint is determined.

When there is no hole in the cam surface, the contact surface pressure is highest at the top of the cam peak and lowest at the bottom of the valley as shown in FIG.

In the present invention, the lubrication hole 26 is formed at the bottom of the valley where the contact surface pressure is lowest, and as shown in FIG. Since the contact pressure is set lower than the upper contact surface pressure, the torque capacity of the joint does not decrease.

Further, the thickness of the cam 1 has a predetermined thickness for securing the cam strength and coupling with the torque transmitting portion, and basically has a margin for providing the lubrication hole 26. Therefore, even if the lubrication hole 26 is provided in the cam 1, the size of the joint does not increase. Further, since there is no need to provide the lubrication hole 26 in the shaft core, the cost does not increase. Also, if the cam 1 is in the up position during lubrication, the lubrication hole 26 is located almost at the top of the plunger chamber 7 so that air can be easily released during lubrication and the taper plug 28 can be mounted after lubrication. There is no danger of air mixing.

[Effects of the Invention] As described above, according to the present invention, since the lubrication hole is formed at the bottom of the cam, the lubrication is performed at a low cost without increasing the size of the joint, reducing the torque capacity. And air bleeding.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a view taken along the line AA of FIG. 1, FIG. 3 is a view taken along the line BB of FIG. 1, and FIG. FIG. 5 is a graph showing the relationship between the rotation angle and the contact surface pressure when there is no hole in the surface, and FIG. 5 is a graph showing the relationship between the rotation angle and the contact surface pressure in one embodiment of the present invention. In the figure, 1: cam, 2: cam surface, 3: output shaft, 4: cam housing, 5: rotor, 6: input shaft, 7: plunger chamber, 8: plunger,
9: return spring, 10: suction / discharge hole, 11: rotary valve, 12: suction port, 13: suction path, 14: discharge port, 16:
Rollers for needle bearings, 17: orifice, 18: notch, 19: projection, 20: thrust block, 21: bearing, 2
2: Needle bearing, 23: Accumulator piston, 2
4: Retainer, 25: Return spring, 26: Lubrication hole, 27:
Taper screw hole, 28: Taper plug, 29: Oil seal, 3
0: stop ring, 31: bolt, 32: bearing,

Claims (1)

(57) [Scope of request for utility model registration] A plunger pump driven by a cam having a plurality of cam lobes driven by a rotation speed difference between first and second rotatable members rotatable relative to each other; Means for generating flow resistance in the discharge path of the hydraulic power transmission joint in which the torque between the first and second rotating members is controlled by the flow resistance, wherein an oiling hole is provided at a bottom of the cam. A hydraulic power transmission coupling characterized in that: