JP2572876B2 - Hydraulic power transmission coupling - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic power transmission coupling used for distribution of driving force of a vehicle.

[Prior Art] The present applicant has proposed the following hydraulic power transmission coupling in Japanese Patent Application No. 2-40632 (see Japanese Patent Application Laid-Open No. 3-244835).

That is, the hydraulic power transmission coupling is provided between an input / output shaft that is rotatable relative to each other, and a plunger pump driven by a rotational speed difference between the two shafts, and a means for generating flow resistance in a discharge path of the pump A power transmission joint, wherein a transmission torque between the input and output shafts is controlled by the flow resistance, a cam housing connected to the one shaft and having a cam surface having two or more peaks on an inner surface; A rotor member connected to the other shaft and rotatably housed in the cam housing to form a plurality of plunger chambers; each of the plurality of plunger chambers being pressed by a return spring; A plurality of plungers housed in a reciprocally movable manner and driven by the cam surface when the two shafts rotate relative to each other; formed on the rotor member; A suction hole and a discharge hole communicating with the plunger chamber; rotatably slidably contacting the rotor member; being rotatably positioned with respect to the cam housing by a predetermined angle; A plurality of suction ports that act as a suction valve and a discharge valve depending on the positional relationship with the suction hole and the discharge hole in any case of reverse rotation,
A valve body having a discharge port, a high-pressure chamber formed by communicating each of the discharge ports with a discharge path and a communication path, a suction path connecting the suction port and a low-pressure chamber in a joint, and a high-pressure chamber. Flow resistance generating means is provided at the outlet to the low pressure chamber.

[Problems to be Solved by the Invention] However, in such a conventional hydraulic power transmission coupling, the discharge chambers communicate with each other by a groove provided on the shaft portion of the rotor or the surface of the valve body, and the collective chamber is formed. (High-pressure chamber) and a rotary seal structure that seals leakage of high-pressure oil by the clearance between the inner diameter portion and the outer diameter portion of the valve body, and thus has the following problems.

(1) Generally, in an axial plunger pump in which a valve element is provided on the thrust surface of a rotor, the hydraulic reaction force of the plunger chamber acting on the rotor makes the valve element and the rotor adhere to each other, thereby preventing oil leakage from the valve section. doing.

However, since the high pressure also acts on the discharge port and the seal land opened on the surface of the valve, a force is generated that pushes the rotor back against the thrust force and hinders the close contact of the valve portion.

If the hydraulic pressure acting on the surface of the valve is higher than the hydraulic pressure of the plunger chamber, the close contact of the valve portion cannot be maintained and the sealing function of the valve is lost.

The oil pressure on the valve surface increases with an increase in the area of the discharge port opened on the surface and the groove communicating therewith. If the area of the communication groove is widened, there is a problem that the valve portion becomes difficult to contact and no torque is generated. .

As a countermeasure, if the discharge port and the communication groove are made thin, there is a problem that the viscosity resistance of the oil becomes large at a low temperature and the torque becomes large.

In addition, it is possible to maintain the close contact of the valve portion by increasing the inner diameter of the valve body and reducing the area of the communication groove. However, there is a problem in that oil leakage from the clearance of the inner diameter portion of the valve body described below increases. was there.

(2) The amount of oil leaking through a narrow annular gap is generally expressed by the following formula, and is proportional to the diameter and the cube of the gap, and inversely proportional to the viscosity of the oil and the length of the gap.

Q = π * d * ΔP * δ ³ / (12 * μ * L) Q: Leakage amount d: Diameter of the gap ΔP: Pressure difference before and after the gap δ: Radius gap μ: Oil viscosity L: Length of the gap In the conventional example, not only the plunger but also the inner diameter portion of the valve body has the annular gap as described above, and the design is such that much oil leaks through the gap.

Since the viscosity of oil changes with temperature, when the temperature of the joint changes, the amount of leakage changes, and accordingly, the hydraulic pressure generated in the plunger chamber, that is, the torque also changes.

Conventionally, there has been a problem that since the amount of leakage is large, the fluctuation of torque with respect to a temperature change is large.

As a countermeasure against this, if the gap of each part is made small, high processing accuracy is required and the cost becomes high, and if the length of the gap is made long, the length of the joint becomes long.

Further, in the conventional example, when the discharge port and the suction port are short-circuited at the time of shifting from the discharge stroke to the suction stroke, the oil in all the communicating plunger chambers escapes through the short-circuited portion, and the hydraulic pressure decreases. There is a problem that the torque drops, and in order to avoid this, the distance between the discharge port and the suction port is made larger than the diameter of the suction discharge hole of the rotor.

For this reason, the discharge valve is closed before the end of the discharge stroke, so that the pressure in the plunger chamber that has lost the oil outlet sharply increases, so-called a closing phenomenon occurs, and there is a problem that a shocking torque is generated. Was.

It is known that this phenomenon can be counteracted by providing a notch for preventing entrapment between the discharge port and the suction port. However, a high dimensional accuracy of the notch is required, and the processing cost is increased. There were also problems.

The present invention has been made in view of such a conventional problem, and does not increase the length of the gap and does not increase the processing accuracy for a joint that does not require a variable orifice mechanism. Hydraulic power transmission coupling that is compact, lightweight, inexpensive and has little torque change due to temperature by eliminating notches by reducing leakage of the valve part and preventing the trapping phenomenon in principle. It is intended to provide.

[Means for Solving the Problems] In order to achieve the above object, the present invention is provided between input / output shafts that can rotate relative to each other, is connected to the one shaft, and has two or more peaks on an inner surface. A cam housing having a cam surface having the same; a rotor connected to the other shaft, rotatably housed in the cam housing, and having a plurality of plunger chambers formed in an axial direction; and the plurality of plungers. A plurality of plungers housed in each of the chambers so as to be reciprocally movable under the pressure of a return spring, and driven by the cam surface when the two shafts rotate relative to each other; A suction and discharge hole communicating with the chamber; rotatably slidably contacting the end face of the rotor, and being positioned in a predetermined relationship with the cam housing;
A plurality of suction ports that act as a suction valve and a discharge valve depending on the positional relationship with the suction and discharge holes, a valve body having discharge ports formed on the surface thereof, and flow resistance generated by flow of the discharge oil by driving the plunger. A power transmission joint for transmitting a torque corresponding to a rotational speed difference between the two shafts, wherein the plunger chamber is provided so as not to be connected to two or more of the discharge ports at the same time; A flow resistance generating means is provided for each of the discharge ports.

[Operation] In the present invention, the two or more plunger chambers are not connected to one discharge port at the same time without connecting the discharge ports, and
Since the flow resistance generating means is provided in each of the discharge ports, the oil in each plunger chamber in the discharge stroke passes through one independent flow resistance generating means.

Therefore, even when the discharge port and the suction port are short-circuited at the time of transition from the discharge stroke to the suction stroke, the oil in the other plunger chambers does not escape from the short-circuited portion and does not affect the operation of each plunger chamber. .

Therefore, the distance between the adjacent suction port and discharge port can be made smaller than the diameter of the suction / discharge hole of the rotor, and the closing phenomenon can be avoided in principle without providing a closing prevention notch.

In addition, since there is no communication groove on the valve surface that communicates each discharge port in the conventional example, the high-pressure portion that opens on the surface of the valve body is only the discharge port, and the oil pressure for opening the close contact of the valve portion is It becomes smaller than the hydraulic pressure of the plunger chamber acting on the rotor, and the close contact of the valve section is maintained.

Therefore, oil leakage of the valve portion is reduced, torque fluctuation due to temperature change can be reduced, and since sealing is performed on the surface of the valve body, there is no need for an axial length for sealing, and the length of the joint is reduced. It won't be long.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

 1 to 3 are views showing an 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 slidably housed in the plunger chamber 7 via a 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, and each discharge port 14 of the rotary valve 11 is formed with an orifice 17 as flow resistance generating means (FIG. 3,
reference). The delivery 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, when the number of cam lobes is N, 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 closing phenomenon can be avoided without providing the closing 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 and discharge hole 10 of the rotor 5, and the suction path 13, the suction port 12, and the rotor 5
The oil can be sucked into the plunger chamber 7 through the suction / discharge hole 10.

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. Reference numeral 16 denotes 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 and the spring 24. 26 is an oil seal, 27 is a stop ring, 28
Is a bolt, 29 is a lubrication hole, and 30 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 connected to the return spring 9.
To the cam surface 2.

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.

At this time, since the suction / discharge port 10 communicates with the discharge port 14, the plunger 8 pushes the oil in the plunger chamber 7 from the suction / discharge port 10 to the discharge port 14 of the rotary valve 11.

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, as shown in FIG. 3, each discharge port 14 is configured so as not to communicate with each other and to prevent two or more plunger chambers 7 from being connected to one discharge port 14 at the same time. Is done. Each discharge port 14 has a suction passage.
Orifices 17 communicating with 13 are provided.

Therefore, the oil in each plunger chamber 7 in the discharge stroke passes through one independent orifice 17. For this reason, even when the discharge port 14 and the suction port 12 are short-circuited as shown in FIG. It does not escape and does not affect the operation of each plunger chamber 7.

Therefore, as shown in FIG. 4 (a), the distance between the adjacent suction port 12 and discharge port 14 can be made smaller than the diameter of the suction and discharge hole 10 of the rotor 5, and as shown in FIG. 4 (c). Even if the notch 31 for preventing the closing is not provided, the closing phenomenon as shown in FIG. 4B can be avoided in principle.

In addition, since the communication groove of the rotary valve communicating with each discharge port in the conventional example is also eliminated, only the discharge port 14 is opened on the surface of the rotary valve 11 and the oil for opening the close contact of the valve portion is opened. The pressure becomes smaller than the hydraulic pressure of the plunger chamber 7 acting on the rotor 5, and the close contact of the valve portion is maintained.

Further, in the conventional example, a mechanism for changing the opening degree of the orifice according to the discharge pressure is provided. Since this mechanism is large, it has to be arranged at the center of the shaft, and high-pressure oil is guided to the center of the shaft. Although a communication groove was provided in the shaft portion because of necessity, in the case of an application that does not require a variable orifice mechanism as in the present embodiment, it is not necessary to provide a communication groove in the shaft portion, so the rotary valve 11 Oil leakage from the inner diameter gap can be prevented.

Therefore, oil leakage of the valve portion is reduced, torque fluctuation due to temperature change can be reduced, and since sealing is performed on the surface of the rotary valve 11, an axial length for sealing is not necessary. Also, the length of the joint does not increase.

[Effects of the Invention] As described above, according to the present invention, since the structure is such that the trapping phenomenon does not occur in principle, it is possible to prevent the generation of a shocking torque, and to reduce the notch. Since it can be abolished, costs can be reduced.

In addition, the oil pressure for opening the close contact of the valve section is smaller than the hydraulic pressure of the plunger chamber acting on the rotor, the close contact of the valve section is maintained, the oil leakage of the valve section is reduced, and the torque due to the temperature change is reduced. Since the fluctuation can be reduced and the sealing is performed at the surface of the valve body, no axial length is required for the sealing, and the length of the joint is not increased.

[Brief description of the drawings]

 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a view taken along the line AA in FIG. 1, FIG. 3 is a view showing an orifice provided in a discharge port, and FIGS. (c) is an explanatory diagram of the confinement phenomenon. 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 ... Rolling wheel for needle bearing 17 ... Orifice, 18 …… Notch, 19 …… Protrusion, 20 …… Thrust block, 21 …… Bearing, 22 …… Needle bearing, 23 …… Accumulator piston, 24 …… Retainer, 25 …… Return spring, 26 …… Oil seal , 27… stop ring, 28… bolt, 29… lubrication hole, 30… bearing.

Claims (2)

(57) [Claims] A cam housing provided between input and output shafts rotatable relative to each other and connected to said one shaft and having a cam surface having two or more peaks on an inner surface; and connected to said other shaft. And a rotor rotatably housed in the cam housing and having a plurality of plunger chambers formed in the axial direction; and a plurality of plunger chambers being reciprocally movable by being pressed by a return spring in each of the plurality of plunger chambers. A plurality of plungers housed and driven by the cam surface when the two shafts rotate relative to each other; a suction / discharge hole formed in the rotor and communicating with the plunger chamber; and a rotatable end face of the rotor. A plurality of sliding contacts are formed and positioned in a predetermined relationship with the cam housing, and act as a suction valve and a discharge valve depending on the positional relationship with the suction and discharge holes. A valve body having a suction port and a discharge port formed on the surface thereof; and a means for generating flow resistance by the flow of the discharge oil by driving the plunger; power transmission for transmitting a torque corresponding to a rotational speed difference between the two shafts. In the joint, the plunger chamber is provided so as not to be connected to two or more of the discharge ports at the same time, and flow resistance generating means is provided at each of the discharge ports. Transmission coupling. 2. The hydraulic power transmission coupling according to claim 1, wherein an interval between the suction port and the discharge port is smaller than a diameter of the suction and discharge hole.